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+The Project Gutenberg EBook of The Bacillus of Long Life, by Loudon Douglas
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: The Bacillus of Long Life
+       a manual of the preparation and souring of milk for dietary
+       purposes, together with and historical account of the use
+       of fermente
+
+Author: Loudon Douglas
+
+Release Date: March 18, 2010 [EBook #31691]
+
+Language: English
+
+Character set encoding: UTF-8
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE BACILLUS OF LONG LIFE ***
+
+
+
+
+Produced by Peter Vachuska, Turgut Dincer, Chuck Greif and
+the Online Distributed Proofreading Team at
+https://www.pgdp.net
+
+
+
+
+
+
+
+  ┌─────────────────────────────────────────────────────────┐
+  │ Transcriber's note:                                     │
+  │                                                         │
+  │ Words in bold characters are enclosed within "+" signs. │
+  │ The list of Putnam Science Series has been moved to the │
+  │ advertisement section at the end of the book. The UTF-8 │
+  │ version of the text file will require a Unicode capable │
+  │ text reader to display a few Greek characters and "oe"  │
+  │ ligatures which occur in the book.                      │
+  └─────────────────────────────────────────────────────────┘
+
+
+
+
+  [Illustration: THE OLDEST WOMAN IN THE WORLD AND HER SON
+
+  Baba Vasilka is 126 years old, and her son Tudor is 101.
+  They are peasants, and have lived all their lives in a
+  little village in Bulgaria. They are typical examples of
+  people who live to a great age by the use of soured milk,
+  as it has been their principal food all their lives.]
+
+
+                         The
+                Bacillus of Long Life
+
+  A Manual of the Preparation and Souring of Milk for
+    Dietary Purposes, Together with an Historical
+     Account of the Use of Fermented Milks, from
+        the Earliest Times to the Present Day,
+         and Their Wonderful Effect in the
+           Prolonging of Human Existence
+
+                         By
+             Loudon M. Douglas, F.R.S.E.
+
+               _With 62 Illustrations_
+
+
+                 G. P. Putnam's Sons
+                 New York and London
+               The Knickerbocker Press
+                        1911
+
+
+                  _Revised Edition_
+
+
+                    COPYRIGHT, 1911
+                         BY
+                  G. P. PUTNAM'S SONS
+
+
+             The Knickerbocker Press, New York
+
+
+
+
+PREFACE
+
+
+This book has been designed with a view to meet an extensive demand for
+definite data on the subject of Soured Milks. The author has had this
+matter brought before him, times without number, by those inquiring for
+authentic information on the subject, and he has therefore considered it
+desirable to gather together such information as is available in
+connection with ancient and modern practice. He has endeavoured to
+present this to the reader in concise form.
+
+The author is indebted to many friends for their assistance in getting
+the book together, and would specially mention Dr. H. B. Hutchinson,
+Bacteriologist, Rothamsted Experimental Station, for assistance in
+connection with the bacteriology of fermented milks; Mr. Thomas Douglas,
+of Wimbledon, who has assisted with the chemistry of the subject; Mr. S.
+Javrilovitch, of Belgrade, Servia, for local information and
+illustrations; Dr. Otokar Laxa, Bacteriologist, of Prague, Bohemia, for
+general assistance; the editor of _Bacteriotherapy_, New York, U.S.A.,
+for the use of the group of illustrations 30-44; the publishers of the
+_Centralblatt für Bakteriologie_, Jena, for the group of illustrations
+14-29; and many others, some of whom are referred to in the text.
+
+
+  CONTENTS
+
+
+  CHAPTER                                                    PAGE
+
+     I.—INTRODUCTORY—HISTORICAL                                 1
+
+    II.—FERMENTED MILKS                                        15
+
+   III.—THE CHEMISTRY OF MILK                                  47
+
+    IV.—HANDLING OF MILK                                       68
+
+     V.—THE BACTERIOLOGY OF FERMENTED OR SOURED MILK           84
+
+    VI.—THE PREPARATION OF SOURED MILK IN THE HOUSE           125
+
+   VII.—THE PREPARATION OF SOURED MILK IN THE DAIRY           139
+
+  VIII.—SOURED MILK IN HEALTH AND DISEASE                     151
+
+         INDEX                                                165
+
+
+
+
+ILLUSTRATIONS
+
+
+  FIG.                                                       PAGE
+
+       THE OLDEST WOMAN IN THE WORLD AND HER SON   _Frontispiece_
+
+       THE PASS OF BUKOVA                                       2
+
+       KABYLES SOURING MILK                                     4
+
+       THE HANDLING OF MILK IN THE PYRENEES                     8
+
+       THE CONSTITUENTS OF MILK                                48
+
+   1.—MICRO-PHOTOGRAPH OF A DROP OF WHOLE MILK                 58
+
+   2.—MICRO-PHOTOGRAPH OF SEPARATED MILK                       58
+
+   3.—MICRO-PHOTOGRAPH OF CREAM                                58
+
+   4.—PHOTOGRAPH OF TWO PETRI DISHES, WHICH HAVE BEEN
+         INOCULATED WITH ORDINARY MILK                         60
+
+   5.—THE CREAMOMETER                                          62
+
+   6.—TESTING-GLASS FOR EXTRANEOUS MATTER IN MILK              62
+
+   7.—LACTOMETER AND TEST-GLASS                                64
+
+   8.—PASTEURISER                                              78
+
+   9.—CONTINUOUS APPARATUS FOR THE PRODUCTION OF LARGE
+         QUANTITIES OF SOURED MILK                             82
+
+  10.—A MILK-FILLING APPARATUS                                 90
+
+  11.—SECTION THROUGH A KEPHIR GRAIN                           94
+
+  12.—_Streptococcus lacticus_ (GROTENFELDT) GROWING ON
+          LACTOSE-AGAR, STAINED BY GRAM'S METHOD               96
+
+  13.—PHOTO-MICROGRAPH OF PREPARATION FROM ARMENIAN SOURED
+         MILK (MATZOON)                                       106
+
+  14.—GRANULE BACILLUS FROM YOGHOURT. SHREDDED PREPARATION
+         OF A FRESH SKIM-MILK CULTURE                         110
+
+  15.—GRANULE BACILLUS FROM YOGHOURT, CULTIVATED AFTER
+         THE USUAL AGAR METHOD                                110
+
+  16.—GRANULE BACILLUS FROM YOGHOURT. AGAR MILK SUGAR
+         CULTURE                                              110
+
+  17.—_Bacteria W._ FROM MILK, CULTIVATED TWENTY-FOUR
+          HOURS                                               110
+
+  18.—AGAR MILK SUGAR CULTURE. FROM THE ORIGINAL BULGARIAN
+         YOGHOURT                                             112
+
+  19.—AGAR MILK SUGAR CULTURE. SURFACE COLONY OF GRANULE
+         BACILLUS FROM CALF'S STOMACH                         112
+
+  20.—AGAR MILK SUGAR CULTURE. DEEP-LYING COLONY
+         OF GRANULE BACILLUS FROM CALF'S STOMACH              112
+
+  21.—AGAR MILK SUGAR. COLONY OF _Bacterium W._ FROM
+         YOGHOURT                                             112
+
+  22.—TWO COLONIES OF _Bacillus Acidophilus_ FROM CALVES'
+         MANURE                                               114
+
+  23.—BEER-WORT GELATINE                                      114
+
+  24.—SHREDDED PREPARATION OF BULGARIAN ORIGINAL YOGHOURT     114
+
+  25.—GRANULE BACILLUS FROM YOGHOURT. CULTIVATED IN SKIM
+         MILK IN TWENTY-FOUR HOURS                            114
+
+  26.—_Bacteria W._, AGAR MILK SUGAR CULTURE                  116
+
+  27.—_Bacteria acidophilus_ FROM CALVES' MANURE              116
+
+  28.—MUCUS FROM CALF'S STOMACH INOCULATED INTO MILK AFTER
+         EIGHT TRANSFERRINGS                                  116
+
+  29.—DIPLOSTREPTOCOCCUS FROM YOGHOURT. PURE CULTURE IN
+         SKIM MILK                                            116
+
+  30.—PHOTO-MICROGRAPH OF PREPARATION MADE FROM YOGHOURT,
+         SHOWING YEAST CELLS                                  118
+
+  31.—PHOTO-MICROGRAPH OF SMEAR FROM GREEK CURDLED MILK
+         CALLED "GIAOURTI"                                    118
+
+  32.—PHOTO-MICROGRAPH OF SOURED MILK INOCULATED WITH
+         A TABLET CONTAINING VIABLE AND PURE CULTURES OF
+        _Bacillus bulgaricus_                                 120
+
+  33.—PHOTO-MICROGRAPH OF MILK INOCULATED WITH A FERMENT
+         TABLE IN WHICH _Bacillus bulgaricus_ IS NO LONGER
+         VIABLE                                               120
+
+  34.—PHOTO-MICROGRAPH OF SMEAR OF CULTURE OF _Bacillus
+         bulgaricus_                                          122
+
+  35.—_Bacillus bulgaricus_, SHOWING THE CULTURES
+          IN ENGLISH COW'S MILK                               124
+
+  36.—PHOTO-MICROGRAPH OF PURE CULTURE OF _Bacillus
+         bulgaricus_                                          124
+
+  37.—PHOTO-MICROGRAPH OF SMEAR OF COMBINED CULTURE
+         OF _Bacillus bulgaricus_ AND _Bacteria
+         paralacticus_                                        124
+
+  38.—PHOTO-MICROGRAPH OF SMEAR OF ONE-MONTH CULTURE
+         OF _Bacillus bulgaricus_                             126
+
+  39.—PHOTO-MICROGRAPH OF CULTURE OF _Bacillus bulgaricus_
+         IN MALT                                              126
+
+  40.—PHOTO-MICROGRAPH OF SMEAR FROM MILK THAT HAD BEEN
+         ALLOWED TO SOUR SPONTANEOUSLY                        126
+
+  41.—PHOTOGRAPH OF AGAR CULTURE, INOCULATED WITH A LACTIC
+         POWDER                                               128
+
+  42.—PHOTOGRAPH OF TEST-TUBES OF STERILE MILK, INOCULATED
+         WITH A TABLET PREPARATION SAID TO CONTAIN PURE
+         CULTURES                                             128
+
+  43.—PHOTOGRAPH OF TEST-TUBES OF STERILE MILK, EACH TUBE
+         HAVING BEEN INOCULATED WITH A TABLET OF A
+         PREPARATION SAID TO CONTAIN PURE CULTURES            128
+
+  44.—PHOTOGRAPH OF TEST-TUBES OF STERILE MILK INOCULATED
+         WITH A TABLET OF "LACTOBACILLINE"                    130
+
+  45.—APPARATUS OF "LE FERMENT" CO.                           129
+
+  46.—SOURED MILK APPARATUS OF THE MAYA BULGARE COMPANY,
+         LIMITED                                              130
+
+  47.—LACTIC FERMENTS, LIMITED, APPARATUS                     131
+
+  48.—MESSRS. ALLEN & HANBURY'S SOURED MILK APPARATUS         132
+
+  49.—VIRONELLE APPARATUS FOR SOURING MILK, MADE BY
+         MESSRS. CLAY, PAGET & COMPANY, LIMITED               132
+
+  50.—"LACTOBATOR" MADE BY MESSRS. CHARLES HEARSON & CO.,
+          LIMITED                                             140
+
+  51.—MESSRS. HEARSON & COMPANY'S "LACTOBATOR"                142
+
+  52.—EDGAR'S "LACTOGENERATOR," SOLD BY THE DAIRY SUPPLY
+         CO., LIMITED                                         143
+
+  53.—APPARATUS OF THE WILLOWS REFRIGERATING CO., LIMITED     144
+
+  54.—"LACTO" APPARATUS OF THE DAIRY OUTFIT CO., LIMITED      145
+
+  55.—STERILISING APPARATUS FOR STERILISING MILK ON
+         THE LARGE SCALE                                      146
+
+  56.—ANOTHER METHOD OF STERILISING (DAIRY SUPPLY
+         CO., LTD.). AN AMERICAN APPARATUS FOR PREPARING
+         SOURED MILK                                          148
+
+  57.—AN AMERICAN APPARATUS FOR PREPARING SOURED MILK         149
+
+
+
+
+THE BACILLUS OF LONG LIFE
+
+
+
+
+CHAPTER I
+
+INTRODUCTORY—HISTORICAL
+
+
+The milk industry is one of the oldest known to mankind, and it is
+difficult to imagine a time when milk in one way or another did not form
+a part of the diet of the human race. There is a good deal of evidence
+to show that in Paleolithic and Neolithic times, cattle were part of the
+possessions of the nomadic races; and, according to the Vedas, the
+manufacture of butter was known in India 1500 years B.C.
+
+In the eastern part of Europe, milk has always been looked upon as one
+of the principal kinds of food, but not necessarily the milk of cows,
+as, from ancient times to the present day, the milk from camels,
+buffaloes, sheep, and goats has been used indiscriminately throughout
+the East.
+
+According to Layard,[1] "the Bedouins do not make cheese. The milk of
+their sheep and goats is shaken into butter or turned into curds; it is
+rarely or never drunk fresh, new milk being thought very unwholesome, as
+soon by experience I found it to be, in the desert. I have frequently
+had occasion to describe the process of making butter by shaking the
+milk in skins. This is also an employment confined to women, and one of
+a very laborious nature. The curds are formed by boiling the milk, and
+then putting some curds made on the previous day into it and allowing it
+to stand. When the sheep no longer give milk, some curds are dried, to
+be used as a leaven on a future occasion. This preparation, called
+_leben_, is thick and acid, but very agreeable and grateful to the taste
+in a hot climate. The sour milk, or _sheneena_, a universal beverage
+amongst the Arabs, is either buttermilk pure and diluted, or curds mixed
+with water.
+
+  [Illustration: THE PASS OF BUKOVA.—During the revolution
+  of 1904, a number of Turkish soldiers, just before
+  traversing this pass, were given coffee containing "café"
+  by a Bulgarian coffee-seller, or keeper of a small khan.
+  Whilst in the pass the poison began to take effect, and
+  they realized that they had been poisoned. Fortunately for
+  them, a peasant with three horses loaded with Yoghourt
+  (soured milk) had taken advantage of their escort. The
+  soldiers ate freely of the Yoghourt, which counteracted
+  the effects of the poison.]
+
+"The camel's milk is drunk fresh. It is pleasant to the taste, rich, and
+exceedingly nourishing. It is given in large quantities to the horses.
+The Shammar and Aneyza Bedouins have no cows or oxen, those animals
+being looked upon as the peculiar property of tribes who have forgotten
+their independence, and degraded themselves by the cultivation of land.
+The sheep are milked at dawn, or even before daybreak, and again in the
+evening on their return from the pastures. The milk is immediately
+turned into leben, or boiled to be shaken into butter. Amongst the
+Bedouins and Jebours it is considered derogatory to the character of a
+man to milk a cow or sheep, but not to milk the camel. The Sheikhs
+occasionally obtain dates from the cities. They are eaten dry with bread
+and leben, or fried in butter, a very favourite dish of the Bedouin...."
+
+The practice is now the same as it was in scriptural times, when milk
+was looked upon as the principal article of diet, and throughout the
+Scriptures there are copious references to milk in different forms, some
+of which are of peculiar interest at the present day.
+
+It may be noticed, for example, that milk is absent from the sacred
+offerings amongst the Hebrews, and this was ascribed by the late
+Professor Robertson Smith to the fact that all ferments were excluded
+from presentation at the altar,[2] it being recognised that, owing to
+the hot climate, milk of all kinds became rapidly sour, and in this way
+came to be looked upon as only fit for consumption when in that
+condition. It has been suggested that the prohibition referred to is on
+the same level as the prohibition of the use of blood, "as milk has
+sometimes been regarded as a kind of equivalent for blood, and
+containing the sacred life."[3] To this day the wandering tribes of
+Arabia consider the milk of their camels and flocks more refreshing when
+it has been slightly fermented or soured by being poured into a
+milk-skin on the inside of which are still sticking sour clots from the
+previous milking, and there shaken for a brief period; but this slightly
+soured milk (the _Oxygala_ of Pliny) is known widely in the East simply
+as leben (milk). The name is also applied to what we term buttermilk.[4]
+
+  [Illustration: KABYLES SOURING MILK
+
+  In the north of Africa the use of soured milk is common,
+  and the illustration shows Kabyles shaking a skin full of
+  milk so as to sour it. The skin has previously been used
+  for the same operation, and, as a consequence, clots of
+  milk are left from the previous day's use, and thus
+  fermentation is set up.]
+
+The use of milk-skins for the carrying of milk is not confined to one
+country, as, while it is common all over the north of Africa, it is also
+known in the Pyrenees and in some parts of the Balkan Peninsula, the
+object being identical in each case; and when it is intended to make
+butter from the milk, the skin is simply rocked between the knees until
+the butter separates, a process of butter-making which was also used
+after the introduction of earthenware churns.[5] Dried soured milk is
+also used by the Arabs, and it is reconstituted when required by rubbing
+it up with a little water, and it is known as _Meeresy_.[6] The ordinary
+soured milk is the common article of diet, and is looked upon as being
+necessary at every meal, and travellers frequently refer to the use of
+this product, as a few references will show.
+
+Charles G. Addison states: "A supper was brought in on a round tray. In
+the centre was a huge pilaff of rice, and around it several small dishes
+of stewed meats, grilled bones, sour clotted milk called _yaoort_,[7]
+bits of meat roasted, etc....
+
+"We retired into a tent to breakfast, where we found an immense bowl of
+delicious fresh camels' milk, with thin hot cakes of unleavened bread,
+baked upon the ashes, ready prepared for us. The principal food of the
+Bedouins consists of flour and some camels' milk made into a paste,
+boiled, and eaten swimming in melted grease and butter; boiled wheat
+and beans dried in the sun and prepared with butter are a favourite
+dish. They are all remarkably fond of butter and grease; the butter is
+made in a goat-skin, suspended to the tent pole, and constantly shaken
+about by the women."[8]
+
+Burckhardt[9] says: "The provisions of my companion consisted only of
+flour; besides flour, I carried some butter and dried leben (sour milk),
+which would dissolve in water. It forms not only a refreshing beverage,
+but is much to be recommended as a preservative of health when
+travelling in summer. These are our only provisions." With regard to the
+inhabitants of the Houran, Burckhardt relates that the most common
+dishes of these people are _bourgoul_ and _keshk_. "In summer they
+supply the place of the latter by milk, leben, and fresh butter. Of the
+bourgoul I have spoken on other occasions; there are two kinds of
+keshk—_keshk-hammer_ and _keshk-leben_. The first is prepared by
+putting leaven into the bourgoul and pouring water over it. It is then
+left until almost putrid, and afterwards spread out in the sun and
+dried, after which it is pounded, and, when called for, served up mixed
+with oil or butter. The keshk-leben is prepared by putting leben into
+the bourgoul instead of leaven; in other respects the process is the
+same. Keshk and bread are the common breakfasts. Towards sunset a plate
+of bourgoul, or some Arab dish, forms the dinner."
+
+Again, Taylor[10] says: "I received a small jug of thick buttermilk, not
+remarkably clean, but very refreshing."
+
+These references particularly refer to the East, from which it would
+appear that soured milk was universally known in ancient times as it is
+at the present day, and this remark applies not only to Egypt,
+Palestine, and Arabia, but throughout Turkey and the Balkan States,
+where the consumption of soured milk is equally common. It seems curious
+that the use of this commodity should have been confined for centuries
+to the East, as we shall see later on that its dietetic value is so
+great that it is really a wonderful thing that no one has taken the
+trouble to introduce its use to the Western nations until quite
+recently.
+
+  [Illustration: THE HANDLING OF MILK IN THE PYRENEES
+
+  The handling of milk in the Pyrenees is, more especially
+  in the villages, conducted in goat or sheep skins, in a
+  similar way to the methods which prevail in Eastern
+  Europe, and the picture shows a skin of milk on a small
+  farm in the Pyrenees. The churning is very often performed
+  by simply rocking the skin between the knees, acidity
+  being induced by remnants of the previous day's milk;
+  souring of milk is induced by the same method.]
+
+A curious example of how the virtues of such an article may be
+independently discovered by another nation is to be found in Lapland,
+where reindeer's milk is the article used. "The reindeer's milk," says
+Acerbi,[11] "constitutes a principal part of the Laplander's food, and
+he has two methods of preparing it, according to the season. In summer
+he boils the milk with sorrel till it arrives to a consistence; in this
+manner he preserves it for use during that short season. In winter the
+following is his method of preparation: The milk, which he collects in
+autumn till the beginning of November, from the reindeer, is put into
+casks, or whatever vessels he has, in which it soon turns sour, and, as
+the cold weather comes on, freezes, and in this state it is kept. The
+milk collected after this time is mixed with cranberries and put into
+the paunch of the reindeer, well cleaned from filth; thus the milk soon
+congeals, and it is cut out in slices, together with the paunch, to
+effect which a hatchet is used, for no smaller instrument would perform
+the office of dividing that lump of ice. It is then separated into small
+pieces and eaten throughout the winter every day at noon, which is the
+Laplander's dinner-hour. It must be presumed, as it is served up without
+being brought to the fire, that this is ice-cream in the greatest
+perfection: here are flesh and fruit blended with the richest
+butyraceous milk that can be drawn from any animal; but, notwithstanding
+the extraordinary fatness, which may be supposed to resist in a great
+degree the effect of cold, this preparation, as our good missionary
+remarks with a degree of feeling, as if his teeth still chattered whilst
+he delivered the account, chills and freezes the mouth in a violent
+manner whenever it is taken. The milk which is drawn late in the winter
+freezes immediately after being drawn. This is put into small vessels
+made of birchwood, and is considered by the Laplander as such an
+extraordinary delicacy, that he reserves it as the most acceptable
+present he can offer even a missionary. It is placed before the fire and
+eaten with a spoon as it is thawed. When put by, it is carefully covered
+up, because if the cold air gets to it afterwards, it turns of a yellow
+colour and becomes rancid."
+
+Amongst the peasants at the present day, soured milk is known as
+_yoghourt_, a word which is spelt differently according to the locality
+in which it is used. The method of preparation is practically the same
+everywhere, and a short description of the process as now carried out
+in one place would, with slight modifications, apply to the general
+method adopted all over the East.
+
+"The culture," says a correspondent at Varna, "which is used for the
+preparation of yogourt, is known as 'Maya' or as 'Bulgarian Maya.' The
+milk which is to be converted into yogourt must first be freed from all
+bacteria by boiling and allowed to cool to the temperature of 45° C.; it
+is then inoculated with maya and maintained at an even temperature of
+45° C. during several hours. There are two kinds of maya, or ferment,
+one known as sour, and the other as sweet maya.
+
+"In Europe small stoves, made expressly for the purpose, are used to
+maintain the milk at the proper temperature. In this country, however,
+after the milk has been boiled, it is merely poured into a bowl and
+allowed to cool to approximately 45° C., then a tablespoonful of this
+tepid milk is well mixed (in a small bowl apart) with a similar quantity
+of maya, and the mixture, when it has become quite homogeneous, is added
+to the bowl of tepid milk and stirred slightly. (One tablespoonful of
+maya is sufficient to ferment one litre of milk.) A cover is then placed
+on the bowl and the whole is enveloped in flannel and left in a warm
+place for three hours in summer, and somewhat longer in winter.
+
+"The process of preparation is complete when the mixture assumes the
+appearance of a soft mass somewhat resembling cream cheese, but less
+solid. The flannel is then removed, the bowl uncovered and placed in a
+cool spot until needed for consumption. Of the yogourt thus prepared, a
+tablespoonful is kept to serve as maya for the following day.
+
+"The best yogourt is prepared from sheep's milk, the second quality from
+buffaloes' milk, and the third quality from cows' milk. Yogourt forms an
+almost daily article of diet with the natives in this country."[12]
+
+With regard to the time stated for the fermenting process, it must be
+noted that since the subject has been investigated so thoroughly, the
+time required for fermentation has been found to be nearer ten than
+three hours, but this will be dealt with in a subsequent chapter.
+
+Historically it may be gleaned from the fragmentary references which we
+have given, that soured milk has, from time immemorial, formed the
+principal article of diet of a great many peoples, and the notable
+feature in connection with it is, that in some countries where it is in
+daily use, the age limit for human beings seems to be very much
+extended, and it would appear that there is a direct connection between
+the use of soured milk and longevity. In Bulgaria, for example, it is
+stated that the majority of the natives live to an age considerably in
+excess of what is recognised as the term of life amongst Western
+nations, and inquiry has shown that in the eastern part of Southern
+Europe, amongst a population of about three millions, there were more
+than three thousand centenarians found performing duties which would not
+be assigned to a man of sixty-five years of age elsewhere. It is quite
+common to find amongst the peasants who live to such a large extent upon
+soured milk, individuals of 110 and 120 years of age.[13]
+
+In the ancient dairy practice, as we have seen, soured milk was the
+principal product, and the extraordinary ages which are recorded of the
+patriarchs, if translated into the modern denomination, would not appear
+to be so imaginary after all, when it is considered that we have
+thousands of examples at the present day of men and women enjoying quite
+as long a term of existence. It has been noticed also, that while these
+very old people are able to perform a certain amount of manual labour,
+there is not the same tendency to the mental decay which is so prominent
+and sad a feature amongst Western nations, at a period of about seventy
+or eighty years of age. It would seem, indeed, as if the habit of living
+long was well known in ancient times, and that, like many other of the
+valuable arts and sciences, it fell under a cloud during the Middle
+Ages, or, perhaps, the significance of the use of soured milk fell into
+neglect, and, even after the revival of letters in the sixteenth
+century, still remained obscure.
+
+The discovery of micro-organisms in perishable products, which is
+attributable to Anthony Van Leeuwenhoek, a Dutchman, whose vocation was
+the polishing of lenses, and who lived between 1632 and 1723, altered
+our point of view, not only of disease, but of all the functions carried
+on by the lower organisms. Since Van Leeuwenhoek's time, the germ theory
+has grown to vast proportions and has more especially been applied with
+splendid results to the study of milk. As we shall see later, the
+researches of modern investigators have led them to the conclusion that
+micro-organisms play such an important part in the milk supply, that it
+is impossible to carry it on safely without a knowledge of the
+bacteriology of the subject. This view began to prevail about 1890, some
+twenty years after Pasteur had shown what fermentation really meant.
+Since that time, the progress in dairying has been continuous, and,
+during recent years, attention has been directed to soured milk to such
+an extent that it has become necessary for all who are interested in the
+handling of milk and milk products to have a knowledge of the subject,
+as it seems clearly demonstrated that, under proper direction, there is
+every possibility of its forming an important element in the
+prolongation of life.
+
+
+
+
+CHAPTER II
+
+FERMENTED MILKS
+
+
+There is considerable variety in the number of soured or fermented
+milks, and they are known by various names, such as Koumiss or Koomiss,
+which is prepared from mares' milk; Keffir, which was originally
+discovered in the mountains of the Caucasus, and which is prepared with
+Keffir grains; Leben, an Egyptian product prepared from the milk of the
+buffalo, cow, or goat; Matzoon, a soured milk which is prepared in
+Armenia from ordinary cows' milk; Dadhi, an Indian preparation from
+cows' milk. All of these owe their special characteristics to the fact
+of their having undergone lactic and alcoholic fermentation.
+
+"Milk left to itself," says Blyth,[14] "at all temperatures above 90° F.
+begins to evolve carbon dioxide, and this is simply a sign and result of
+fermentation. If this fermentation is arrested or prevented, the fluid
+remains perfectly sweet and good for an indefinite time. Besides the
+production of carbon dioxide during decomposition, a certain portion of
+milk sugar is converted into lactic acid, some of the casein and albumen
+are broken up into simpler constituents, and a small proportion of
+alcohol produced, which by oxidation appears as acetic acid, while the
+fat is in part separated into free fatty acids, which ultimately unite
+with the ammonia produced by the breaking up of the albuminoids. The
+main fermentation of milk is a special kind which of late years has been
+much studied, and is known as _lactic fermentation_. Accompanying lactic
+fermentation there is nearly always a weak butyric and a weak alcoholic
+fermentation."
+
+One of the organisms causing _Butyric Acid Fermentation_ is a bacillus 3
+to 10µ in length, and about 1µ in breadth. It has power of movement, and
+when cultivated in gelatine, liquefies the gelatine, forming a scum on
+the surface. When the bacillus is sown into sterile milk, the following,
+according to Hueppe, are the changes:
+
+"If the milk thus infected is incubated, on the second day a clear,
+slightly yellow fluid is seen under the layer of cream; this fluid
+increases from day to day, so that gradually a column of fluid is
+formed which is quite clear above, but below is turbid; the casein, at
+first thrown down in a firm coagulum, in the course of eight days begins
+to be attacked, and by the end of two or three weeks most of it is
+dissolved. The filtered fluid gives the biuret reaction; it contains
+leucin, tyrosin, and ammonia; hence it is clear that the ferment acts to
+some extent as a digestive of albumen. In advanced butyric acid
+fermentation, the fluid is most offensive, and may have an alkaline
+reaction."
+
+Lactic acid was first isolated by Scheele in 1780 from soured milk, but
+its exact constitution was not determined until later by Liebig,
+Mitscherlich, Gay-Lussac, and Pelouze: "It is widely distributed in
+nature, occurring in the sap of the vine and in most fermented liquids,
+especially in soured milk; it is not, however, present in fresh
+milk."[15]
+
+In all the Eastern preparations referred to, the lactic fermentation is
+produced, followed by alcoholic fermentation, which is due to the slow
+decomposition of the milk sugar, the vinous fermentation being most
+readily set up in milks which contain a larger relative proportion of
+milk sugar and water, such as the milk derived from the mare, the sheep,
+and the camel. As these fermented milks have different characteristics,
+it is necessary to the thorough understanding of the process of
+manufacture at the present day, to examine them in some detail.
+
+_Koumiss._—The greatest of all the fermented milks is koumiss, and it
+has been celebrated from the most ancient times until the present day,
+as being the principal food of the wandering tribes of Khirgiz,
+Bashkirs, Kalmucks, and Tartars, who inhabit the steppes of European
+Russia and the plains of South, Western, and Central Asia. According to
+Carrick, who has written an interesting volume on the subject,[16] the
+nomads who inhabit these vast territories are shut up under the most
+miserable circumstances during the winter time and at the advent of
+spring they roam over the steppes from morning to night, usually in the
+saddle. The milk yielded at such time by the mares is carefully
+collected, and these nomads consume enormous quantities of it in the
+fermented state, this habit having been in existence amongst them from
+time immemorial. It is said that the Scythians, long before the
+Christian era, used fermented mares' milk; and there are ornaments in
+existence in Russia, of Scythian origin, which exhibit in detail the
+preparation of koumiss from mares' milk. In historical times, the first
+mention of koumiss was in the twelfth century, when it is referred to in
+the Ipatof Chronicles. During the thirteenth century William de
+Rubruquis, a French missionary, wrote about his travels in Tartary, and
+he described how he had first become acquainted with koumiss, and how he
+found it savoury to the palate. Subsequent to this, however, there is
+very little mention of koumiss in Russian history, or, for that matter,
+in any other, and the first really scientific contribution on the
+subject was by Dr. John Grieve, who was a surgeon in the Russian army,
+and who in the year 1784 sent a description of koumiss to the Royal
+Society of Edinburgh,[17] of which he was a member, and the title of it
+was, "An Account of the Method of Making Wine called by the Tartars
+Koumiss, with Observations on its Use as a Medicine." Dr. Grieve
+strongly advocated the use of koumiss as beneficial in cases of wasting
+diseases, and subsequently it was adopted by the medical profession,
+with the result that sanatoria for the treatment of pulmonary
+consumption were established at Samara and other places in Russia, and
+met with very great success; and at the present day such sanatoria are
+carried on, but the bacteriology of the subject now being thoroughly
+understood, the methods of preparation have been somewhat modified.
+
+An interesting account of koumiss is given by Clarke,[18] who says:
+
+"Everybody has heard of koumiss, and the brandy which the Kalmucks are
+said to distil from the milk of mares. The manner of preparing these
+liquids has been differently related, and perhaps is not always the
+same. They assured us that the brandy was merely distilled from
+buttermilk. The milk which they collect overnight is churned in the
+morning into butter; and the buttermilk is distilled over a fire made
+with the dung of their cattle, particularly the dromedary, which makes a
+steady and clear fire like peat. But other accounts have been given both
+of the koumiss and the brandy. It has been usual to confound them, and
+to consider the koumiss as their appellation for the brandy so obtained.
+By other information I could gain, not only here, but in many other
+camps which we afterwards visited, they are different modifications of
+the same thing although different liquors; the koumiss being a kind of
+sour milk, like that so much used by the Laplanders called _pina_, and
+which has undergone, in a certain degree, the vinous fermentation; and
+the brandy an ardent spirit obtained from koumiss by distillation. In
+making koumiss they sometimes employ the milk of cows, but never if
+mares' milk can be had, as the koumiss from the latter yields three
+times as much brandy as that made from cows' milk.
+
+"The manner of preparing the koumiss is, by combining one sixth part of
+warm water with any given quantity of warm mares' milk. To these they
+add, as a leaven, a little old koumiss, and agitate the mass till
+fermentation ensues. To produce the vinous fermentation, artificial heat
+and more agitation is sometimes necessary. This affords what is called
+koumiss. The subsequent process of distillation afterwards obtains an
+ardent spirit from the koumiss. They call it _vina_. In their own
+language it bears the very remarkable appellation of _rack_ and _racky_,
+doubtless nearly allied to the names of our East India spirit _rack_
+and _arrack_. We brought away a quart bottle of it, and considered it
+very weak bad brandy, not unlike the common spirit distilled by the
+Swedes and other northern nations. Some of their women were busy making
+it in an adjoining tent. The simplicity of the operation and their
+machinery was very characteristic of the antiquity of this chemical
+process. Their still was constructed of mud, or very coarse clay; and
+for the neck of the retort they employed a cane. The receiver of the
+still was entirely covered by a coating of wet clay. The brandy had
+already passed over. The woman who had the management of the distillery,
+wishing to give us a taste of the spirit, thrust a stick, with a small
+tuft of camel's hair at its end, through the external covering of clay,
+and thus collecting a small quantity of the brandy, she drew out the
+stick, dropped a portion on the retort, and, waving the instrument above
+her head, scattered the remaining liquor in the air. I asked the meaning
+of this ceremony, and was answered that it is a religious custom to give
+always the first drop of the brandy which they draw from the receiver to
+their God. The stick having been plunged into the receiver again, she
+squeezed it into the palm of her dirty and greasy hand, and after
+tasting the liquor, presented it to our lips."
+
+Another interesting account of the preparation of koumiss is given by
+John M. Wilson in the _Rural Encyclopædia_,[19] and it shows that the
+methods in use about the middle of last century did not differ
+materially from those which existed centuries before.
+
+Wilson says: "Khoumese is vinously fermented mares' milk. Any quantity
+of fresh mares' milk is put into wooden vessels; a sixth part of water
+just off the boil is mixed with it; an eighth part of old khoumese or of
+the sourest possible cows' milk is added; the mixture is kept from
+fifteen to twenty-four hours, covered up with several folds of coarse
+linen cloth and with a very thick board, and without being stirred or in
+any degree disturbed, in a moderately warm place till it becomes
+thoroughly sour, and sends up a thick mass to its surface; it is then
+beaten and pounded and stirred till the curd is not only broken, but so
+thoroughly mixed with the serum as to form a thick liquid; it next
+remains covered and at rest during twenty-four hours more, and it is
+finally put into a common butter churn and beaten and blended into a
+state of perfect homogeneity. It is now fit for use; yet it acquires an
+increase of given properties if it be allowed to stand for a few days,
+and either then or now it would, if distilled, yield nearly one third of
+its own bulk of a weak spirit which will bear to be rectified. Whenever
+it is used it must be previously so agitated that its component parts
+may be well mixed together, and it may be kept either in pans for
+immediate use or in casks for more remote use; and if placed in a cool
+cellar it will remain good during three or four months."
+
+Mares' milk owes its peculiar fitness for making koumiss to its
+containing a large proportion of sugar of milk, and readily undergoing
+the vinous fermentation, and it possesses a general medicinal reputation
+among the Tartars similar to that which asses' milk has partially
+acquired in Britain. "That mares' milk will undergo vinous fermentation
+and yield a certain quantity of spirit," says a writer in the _Magazine
+of Domestic Economy_, "is not generally known, and it was reserved for a
+nation of demi-savages to render this circumstance available as an agent
+of health, as well as an agreeable and nourishing beverage. Every
+educated person, however, has heard that the Tartars drink mares' milk,
+though few know that this milk is taken on account of its specific
+virtues alone, and not as a substitute for cows' milk, of which they
+have abundance, and with which they adulterate mares' milk when scarce."
+But the koumiss is reputed to be much more medicinal than the mares'
+milk itself; and on account of its being free from all tendency to
+curdle in the stomach, and of its possessing most of the nutritive power
+of the milk in combination with native fermented spirit, it has been
+strongly recommended by some persons as a remedy for most or all cases
+of general debility, of nervous languor, and even pulmonary disease.
+
+"Khoumese is called sometimes _koumiss_ and sometimes milk wine."
+
+From these references it will be seen that koumiss is an alcoholic drink
+made by the fermentation of mares' milk, but it is also frequently
+prepared from the milk of the camel and cows' milk. It is stated that a
+similar preparation to Russian koumiss is made in Switzerland from cows'
+milk simply by the addition of a little sugar and yeast to skim milk;
+"it contains more sugar and less lactic acid than Russian koumiss, and
+on account of the much greater proportion of casein contained in cows'
+milk, differs considerably from that prepared from mares' milk."
+Suter-Naef gives the composition of a Swiss koumiss[20] manufactured at
+Davos as follows:
+
+                      In Grams.             Per Litre
+                      Per cent.            (by weight).
+  Water                90.346               1019.64 grams.
+  Alcohol               3.210                 36.23   "
+  Lactic acid           0.190                  2.14   "
+  Sugar                 2.105                 23.75   "
+  Albuminates           1.860                 20.99   "
+  Butter                1.780                 20.09   "
+  Inorganic salts       0.509                  5.74   "
+  Free carbonic acid    0.177                  2.00   "
+
+The ferments used in the preparation of koumiss are stated by Carrick to
+be of two different kinds, artificial and natural.
+
+"Of the natural ferments two have been resorted to. One is mentioned by
+Grieve, which he borrowed from the Bashkirs of Orenbourg, and which
+simply consists in the addition of one sixth part of water and one
+eighth of the sourest cows' milk to fresh mares' milk; the other has
+been employed, and was, if I mistake not, first recommended by
+Bogoyavlensky. It is a very simple if rather a tedious method. New
+mares' milk, diluted with one third its bulk of water, is placed in the
+_saba_,[21] and while allowed to sour spontaneously, is continually
+beaten up. This milk gradually undergoes the vinous fermentation, and in
+twenty-four hours is converted into weak koumiss. The disadvantage of
+this mode of commencing fermentation is obvious—viz., the great waste
+of time in agitation. Hence it is only employed when no artificial
+ferment is obtainable.
+
+"In starting the process of fermentation in mares' or any other kind of
+milk, therefore, an artificial ferment is more frequently employed than
+a natural one. The former is used only for converting the first portion
+of milk into koumiss; the latter is always resorted to afterwards.
+
+"Of artificial ferments the variety is great, for besides all putrefying
+animal matters which contain nitrogen—such as blood, white of egg,
+glue, and flesh—certain mineral substances which act by souring the
+milk are also capable of exciting fermentation.
+
+"Now, many of the nomads, whose mares either give no milk or are not
+milked in winter, commence the preparation of their koumiss in spring by
+borrowing a ferment from the animal, mineral, or vegetable kingdom. Thus
+a mixture of honey and flour is the favourite ferment with some races of
+nomads; a piece of fresh horse-skin or tendon is preferred by others,
+while a few resort to old copper coins, covered with verdigris, for
+starting fermentation. In the choice of a ferment they are guided solely
+by habit and tradition. As it would be useless, almost impossible, to
+give a list of all the foreign substances that have been employed with
+the view of converting mares' milk into koumiss, it will be best to
+consider the simplest artificial ferments, and those most generally in
+use.
+
+"The simplest way is that recommended by Bogoyavlensky, and adopted and
+modified by Tchembulatof.[22] It is prepared thus: 'Take a quarter of a
+pound of millet-flour, add water to it, and boil it down to the
+consistence of thick oatmeal porridge. Then heat separately, in another
+vessel, eleven pints of milk to boiling-point, and allow it to cool
+down. When its temperature has fallen to 95° F., pour it into a wooden
+bowl or tub, and add the boiled flour to it. The upper and open part of
+the vessel is then covered with a piece of coarse linen, and left at
+rest—at a temperature of about 99° F.—from twenty-four to forty-eight
+hours. The appearance of small bubbles, which keep bursting on the
+surface of this liquid, combined with a vinous or acid odour, prove that
+the ferment is ready. To this fermenting fluid twenty-two quarts of new
+milk are gradually (_i.e._, every ten minutes) added, and the whole mass
+is continuously beaten up for twelve hours. The temperature during
+stirring should never be higher than 94° F. The whole fluid soon begins
+to ferment, and after twelve hours a not unpleasant koumiss is ready.
+This should be filtered through a horse-hair or muslin sieve, after
+which it is fit for drinking. This liquid is called weak koumiss; but a
+limited portion of the lactine has undergone the lactuous and vinous
+fermentations, and thus the percentage of alcohol is small. Koumiss at
+an ordinary temperature remains weak for twelve hours after it has been
+beaten up, and then gradually passes into medium.'"
+
+Curiously enough, the richness of cows' milk in fat militates against
+its being a good raw material for the making of koumiss, owing to the
+production of small quantities of butyric acid, which follows upon the
+fermentation, so that it is desirable, if koumiss is to be prepared from
+cows' milk, that the fat should be first of all eliminated, so that the
+separated milk will then approximate to the composition of mares' milk.
+
+"The chemical changes," says Hutchison,[23] "which take place in the
+milk under the double fermentation are not difficult to follow; the
+lactic ferment simply changes part of the sugar into lactic acid, the
+vinous ferment eats up a very small part of the proteid of the milk,
+and, at the same time, produces from the sugar a little alcohol and a
+good deal of carbon dioxide; the milk thus becomes sour, it effervesces
+and is weakly alcoholic, but the lactic acid causes the casein to be
+precipitated just as it does in the ordinary souring of milk, and the
+casein falls down in flocculi."
+
+As will have been noticed, it is an essential part of the process of
+koumiss-making to keep the milk in a state of agitation during the
+period of fermentation, a process which is intended to permit of oxygen
+being taken up by the fermenting fluid, while, at the same time, the
+casein is broken up into a state of fine division. The casein also, or
+at least a portion of it, becomes very soluble, and after twelve hours
+of fermentation the taste of the product is only slightly sour, and the
+milk taste still remains. This taste, however, disappears in
+twenty-four hours, owing to the rapid development of the lactic acid
+organisms. After this lapse of time the sugar is entirely destroyed, and
+the strong koumiss which results is a thin sour fluid which effervesces
+briskly, and in this condition will keep for an indefinite period. "The
+net change which has taken place in the original milk may be summed up
+by saying that the sugar of the milk has been replaced by lactic acid,
+alcohol, and carbon dioxide, the casein has been partly precipitated in
+a state of very fine division, and partly pre-digested and dissolved,
+while the fat and salts have been left much as they were."[24]
+
+Violent stirring or agitation of the cultures does not seem to work so
+much by supplying oxygen to the fermenting liquid, as by ensuring a
+thorough distribution of the micro-organisms throughout the liquid, and
+thus dividing the casein.
+
+The greater number of the organisms are facultative anærobes and oxygen
+is not necessary. Again, koumiss put up in bottles on the first day is
+regularly shaken although air is excluded.
+
+_Keffir._—Keffir is a kind of fermented milk which has been in use in
+the Caucasus for quite a long time, as koumiss has been in the steppes.
+It differs from koumiss, however, in this respect, that it is prepared
+from either sheep's, goats', or cows' milk. The process is started by
+the addition of keffir grains to the milk, which is contained in
+leathern bottles. These keffir grains are small solid kernels which are
+kept in families and handed on from one generation to another.[25] The
+grains are the origin of the ferment, as they disseminate in the milk
+micro-organisms of a lactic yeast (_Saccharomyces kefir_ Beyerinck and
+Freudenreich) and also the bacillus _Bacterium caucasicum_, which
+develop rapidly and split up the milk sugar into carbon dioxide,
+alcohol, and lactic acid. Small quantities of glycerine, acetic,
+succinic, and butyric acids are also formed, the casein and albumen
+being partly peptonised.[26] Keffir becomes slightly effervescent in
+twenty-four hours, and in that time develops a small quantity of
+alcohol, but after three days the amount of alcohol and lactic acid
+is much increased.[27] It has been determined that the fermentation of
+the milk is due to _Saccharomyces kefir_, and that the _Lactobacillus
+Caucasicus_ does not take any part in the fermentation, a fact which
+seems to be supported by the capacity of ordinary keffir for starting
+the fermentation in fresh milk in the same manner as the keffir grains.
+The use of this beverage seems to be universal throughout the Caucasus,
+and travellers in these regions have frequently referred to it. Thus
+Freshfield[28] states in one part of his book of travels as follows:
+
+"The pig-faced peasant against whom we had at first sight conceived such
+an unjust prejudice turned out a capital fellow. He brought us not only
+fresh milk, but a peculiar species of liquor, something between
+public-house beer and sour cider, for which we expressed the greatest
+admiration, taking care at the same time privately to empty out the
+vessel containing it, on the first opportunity." And again:
+
+"The hospitable shepherds regaled us, not only with the inevitable and
+universal airam or sour milk—if a man cannot reconcile himself to sour
+milk, he is not fit for the Caucasus—but with a local delicacy that
+has lately been brought to the knowledge of Europe—kefir. This may best
+be described as 'effervescing milk.' It is obtained by putting into the
+liquid some yellow grains, parts of a mushroom which contains a bacillus
+known to science as _Dispora caucasia_. The action of the grains is to
+decompose the sugar in the milk, and to produce carbonic acid and
+alcohol. The grains multiply indefinitely in the milk; when dried they
+can be preserved and kept for future use; its results on the digestion
+are frequently unsatisfactory, as one of my companions learnt to his
+cost."
+
+"It has been supposed," says Metchnikoff, "that the chief merit of
+kephir was that it was more easy to digest than milk, as some of its
+casein is dissolved in the process of fermentation. Kephir, in fact, was
+supposed to be partly digested milk. This view has not been confirmed.
+Professor Hayem thinks that the good effects of kephir are due to the
+presence of alcoholic acid, which replaces the acid of the stomach and
+has an antiseptic effect. The experiments of M. Rovigh, which I speak of
+in _The Nature of Man_, have confirmed the latter fact, which now may be
+taken as certain. The action of kephir in preventing intestinal
+putrefaction depends on the lactic acid bacillus which it contains.
+Kephir, although in some cases certainly beneficial, cannot be
+recommended for the prolonged use necessary, if intestinal putrefaction
+is to be overcome.... Professor Hayem prohibits its use in the case of
+persons in whom food is retained for long in the stomach. When it is
+retained in the stomach, kephir goes on fermenting, and there are
+developed in the contents butyric and acetic acids, which aggravate the
+digestive disturbances. Kephir is produced by combined lactic and
+alcoholic fermentations ... and it is the lactic and not the alcoholic
+fermentation on which the valuable properties of kephir depend; it is
+correct to replace it by sour milk, that contains either no alcohol or
+merely the smallest traces of it. The fact that so many races make sour
+milk and use it copiously is an excellent testimony of its usefulness."
+
+There are two methods given by Flügge[29] for the preparation of keffir:
+
+"In the first, the dry brown kefir grains of commerce are allowed to lie
+in water for five or six hours until they swell; they are then carefully
+washed and placed in fresh milk, which should be changed once or twice
+a day until the grains become pure white in colour and when placed in
+fresh milk, quickly mount to the surface—twenty to thirty minutes. One
+litre of milk is then poured into a flask, and a full tablespoonful of
+the prepared _körner_ added to it. This is allowed to stand open for
+five to eight hours; the flask is then closed and kept at 18° C. It
+should be shaken every two hours. At the end of twenty-four hours the
+milk is poured through a fine sieve into another flask, which must not
+be more than four fifths full. This is corked and allowed to stand,
+being shaken from time to time. At the end of twenty-four hours a drink
+is obtained which contains but little carbon-dioxide or alcohol. Usually
+it is not drunk until the second day, when, upon standing, two layers
+are formed, the lower milky, translucent; and the upper containing fine
+flakes of casein. When shaken it has a cream-like consistence. On the
+third day it again becomes thin and very acid. The second method is used
+when one has a good kefir and two or three days to start with. Three or
+four parts of fresh cows' milk are added to one part of this and poured
+into flasks which are allowed to stand for forty-eight hours with
+occasional shaking. When the drink is ready for use, a portion (one
+fifth to one third) is left in the flask as ferment for a fresh quantity
+of milk. The temperature should be maintained at about 18° C., but at
+the commencement a higher temperature is desirable. The grains should be
+carefully cleaned from time to time and broken up to the size of peas.
+The clean grains may be dried upon blotting-paper, in the sun, or in the
+vicinity of a stove; when dried in the air they retain their power to
+germinate for a long time."
+
+_Leben._—In our earlier references to fermented milks in scriptural
+times, we observed that alcoholic fermented milks were not permitted to
+be presented at the altar. Such offerings, however, were quite allowable
+amongst the ancient Egyptians, the Arabs and Carthaginians,[30] and from
+remote antiquity these nations placed great value on this product.
+Leben, which is peculiarly associated with Egypt, is a soured milk
+prepared from the milk of buffaloes, cows, or goats. It is usually
+prepared by the boiling of the fresh milk over a slow fire, after which
+some fermented milk from a previous preparation is added to the warm
+article, and the fermentation takes place rapidly and is considered to
+be complete in about six hours.[31] The Egyptian leben is valued so
+highly that it is offered in hospitality to the passing stranger, and it
+is regarded as so much of a duty to present this milk, that in some
+parts of Arabia it would be looked upon as scandalous if any payment
+were received in return.[32]
+
+_Matzoon._—Matzoon is prepared in Armenia in somewhat the same manner
+as keffir is prepared in the Caucasus, and indeed it differs very
+slightly from keffir in composition. Its use is universal in Armenia.
+
+_Dadhi._—In India large quantities of fermented milk are used, under
+the name of Dadhi, and its characteristics are not unlike the similar
+products in Europe. The specific bacillus has been investigated by
+Chatterjee,[33] who concludes that it is somewhat akin to the _Bacillus
+bulgaricus_ and the bacillus of leben (_B. lebenis_). Dr. Chatterjee
+gives a résumé of his investigations which sums up the whole matter
+thus:
+
+"1. The fermented milk of India called Dadhi resembles in all essential
+points the Bulgarian fermented milk as well as the leben and other forms
+of fermented milk in use in the East.
+
+"2. The causative element of the curdling process of Dadhi is a
+streptothrix having characters similar to the _Bacillus bulgaricus_ and
+_Streptobacilli lebeni_, and _Bacillus caucasina_ and the Long Bacilli
+of Mazun, in (1) not growing in ordinary media; (2) producing a large
+amount of lactic acid in milk; (3) producing, besides coagulation of
+casein and splitting up the sugar of milk into lactic acid, no other
+change in milk; (4) not producing any indol, nor peptone, nor
+saponification of fat, nor formation of any gas.
+
+"3. It differs from the above by showing peculiar pink-stained granules,
+when stained with methylene blue and showing peculiarly convoluted
+chains in glucose agar.
+
+"4. The importance of the organism lies in the fact that, as in the case
+of _Bacillus bulgaricus_, it kills all pathogenic non-sporing germs and
+also destroys all proteolytic gas-forming bacilli in milk."
+
+In the account of these investigations the following table is given,
+showing the amount of lactic acid produced by different lactic acid
+bacilli in one litre of milk, in terms of lactic acid—the culture
+being kept at 37° C.
+
+  ┌──────────────┬───────┬───────┬───────┬───────┬───────┬───────────────────┐
+  │ Name of the  │ After │ After │ After │ After │ After │                   │
+  │  Bacillus.   │  24   │  48   │  72   │  96   │  a    │    Remarks        │
+  │              │ Hours.│ Hours.│ Hours.│ Hours.│ Week. │                   │
+  ├──────────────┼───────┼───────┼───────┼───────┼───────┼───────────────────┤
+  │ B. lactis    │  1.8  │  ...  │ 10.08 │  ...  │  ...  │ Observed by       │
+  │  ærogenes    │       │       │       │       │       │  Hall and Smith   │
+  │              │       │       │       │       │       │                   │
+  │ B. coli      │  1.8  │  ...  │  4.77 │  ...  │  ...  │ Observed by       │
+  │  communis    │       │       │       │       │       │  Hall and Smith   │
+  │              │       │       │       │       │       │                   │
+  │ B.           │ 12.8  │ 16.5  │ 20.2  │  ...  │  22.0 │ Observed by       │
+  │  bulgaricus  │  -.4  │  -.4  │  -.4  │  ...  │   -.4 │  Gabriel Bertrand │
+  │              │       │       │       │       │       │  and Weisweller;  │
+  │              │       │       │       │       │       │  the initial      │
+  │              │       │       │       │       │       │  acidity of the   │
+  │              │       │       │       │       │       │  milk was 4       │
+  │              │       │       │       │       │       │                   │
+  │ Matzoon Long │ 10.8  │ 12.0  │  ...  │  ...  │  ...  │ Observed by       │
+  │  stäbschen B.│       │       │       │       │       │  Düggeli          │
+  │              │       │       │       │       │       │                   │
+  │ Strepto-     │2.61[34]  ...  │  ...  │  ...  │  ...  │ Observed by       │
+  │  bacillus    │       │       │       │       │       │  Rist and Khoury  │
+  │  lebenis     │       │       │       │       │       │                   │
+  │              │       │       │       │       │       │                   │
+  │ Streptothrix │ 10.8  │  1.08 │ 11.25 │ 11.70 │  18.5 │ Med. Coll.,       │
+  │  dadhi       │       │       │       │       │       │  Calcutta         │
+  └──────────────┴───────┴───────┴───────┴───────┴───────┴───────────────────┘
+
+In different parts of the world sour milk is consumed in great
+quantities, and it is stated by Metchnikoff[35] that the chief food of
+the natives of tropical Africa consists of soured milk, and in Western
+Africa in the region south of Angola, the natives live almost entirely
+on this product, there being a difference in the curdled milks produced
+according to the nature of the microbial flora which is introduced.
+
+It is stated[36] that in Servia, Bulgaria,[37] and Roumania there were
+5000 centenarians living in 1896, and while many reasons are advanced
+for such an abnormal condition of affairs, it seems fairly certain that
+the sole reason why people in these districts live to such great ages is
+because of their mode of living and the fact that they live very largely
+on soured milk. The hygienic conditions throughout these countries are
+not such as would give the population in the towns and villages any
+special advantages in the prolongation of life, and while it may be
+stated that a pastoral and agricultural life are likely to contribute to
+longevity, these conditions would not account for a general tendency to
+live long in the countries referred to, more than in any other
+agricultural area. There are many countries throughout the world in
+which the pastoral and agricultural existence is general, but it has
+not been shown that in these countries life is prolonged. Hence the
+conclusion has been forced upon investigators that the reason is to be
+found not in the pastoral conditions, but in the habit which has existed
+from time immemorial of consuming sour milk as a principal article of
+diet.
+
+There is no curtailment of the use of fermented milks in Eastern Europe,
+and the methods of preparation at the present day are those which have
+been carried out from time immemorial. A local observer states that in
+Bulgaria yoghourt is made in nearly every household, especially in the
+spring and summer. The method of preparation is very simple: The milk is
+boiled until a quarter of its volume has evaporated, it is then cooled
+to 45° C. and the ferment added. This ferment is a portion of the
+yoghourt of good flavour and is called "Maya" or "Zakvaska." The vases,
+a kind of earthenware pot, are enveloped in woollen stuff or sheepskin
+and placed in a warm place near the chimney. In ten hours the yoghourt
+is made, and it is preserved in a cold place. The great reputation that
+the yoghourt has acquired in Western Europe has caused this "Maya" to
+become an article of commerce. It is sent out by rail hermetically
+sealed in tinplate boxes. According to a Sophia chemist, the "Maya" is
+employed in the following manner: For a litre of milk it is necessary to
+take about 10 gr. of the ferment. This ferment is diluted with three
+times the amount of water and put into a bowl previously heated with hot
+water and dried. Into this bowl the milk, previously boiled and cooled
+to a temperature of 75° to 50° C., is poured; it is then covered over
+and put in a temperature of about 30° C., and, in default of a stove of
+constant temperature, the bowl is wrapped round with flannel or a plaid,
+and left to curdle for eight to ten hours. It is then ready for
+consumption. During winter, curdled milk keeps for several days, and in
+summer it becomes sour in from twelve to twenty-four hours.
+
+A similar food to the yoghourt is prepared in the Balkan mountains from
+sheep's milk under the name of "Urgoutnik."[38] The milk is poured into
+a goat-skin or sheepskin bag, and a little of the fermented milk added,
+and is then left for some hours in a warm place. The milk consumed is
+replaced by a fresh supply. In some of the Balkan countries, they are
+not content with the fermentation of the milk, they add a little alum,
+which, under the name of "typsa," is well known for this purpose. The
+milk attains such a solid consistency that it can be put into a cloth
+and carried to market.[39]
+
+The various forms of sour milk which have been described in the
+foregoing pages may be said to be of the traditional kind, and with the
+light of modern knowledge, it has been possible to determine exactly
+what constitutes the active principle in use in the milk consumed in
+these countries, and, as we shall see, this principle has been applied
+so that, at the present day, a pure fermented milk may be obtained in
+any country, and there is every reason to believe that should such be
+adopted as a general article of food, it would contribute to the
+prolongation of human existence.
+
+It is due to Metchnikoff, of the Pasteur Institute, that so much
+prominence has been given to the use of fermented milks. He gave it as
+his opinion[40] that senility was caused partly by auto-intoxication or
+by the poison derived from putrefactive micro-organisms which inhabit
+the digestive track. These organisms increase with age, and under
+certain unhealthy conditions multiply enormously, particularly in the
+large intestine. Having arrived at this knowledge, Metchnikoff set to
+work to devise some means of combating the influence of these harmful
+microbes, and set up the hypothesis that the tendency to longevity which
+is exhibited in Eastern countries is due to the consumption of lactic
+acid organisms in the shape of soured milk. These organisms are more
+powerful than those of a putrefactive character and inhibit their
+growth.
+
+"In the presence of such facts," says Metchnikoff, "it becomes
+exceedingly important to find some means of combating the intestinal
+putrefaction which constitutes so incontestable a source of danger. Such
+putrefaction is not only capable of producing diseases of the digestive
+tube—_enteritis_ and _colitis_—but even of becoming a source of
+intoxication of the organism in its most varied manifestations.
+
+"It is some years since I proposed to combat intestinal putrefaction and
+its injurious consequences by means of lactic ferments. I thought the
+acidity produced by such microbes would be much more effective in
+preventing the germination of putrefying microbes than the small
+quantity of acids produced by _Bacillus coli_. On the other hand, I had
+no illusion as to the difficulty sure to be encountered in any effort to
+introduce lactic microbes into the intestinal flora which has been
+preoccupied by a multitude of other microbes. To make surer of the
+result, I chose the lactic microbe, which is the strongest as an acid
+producer. It is found in the _yahourt_ (yoghourt), which originates in
+Bulgaria. The same bacillus has also been isolated from the _leben_ of
+Egypt; and it is now proved that it is found in the curdled milk of the
+whole Balkan peninsula, and even in the Don region of Russia."[41]
+
+It is a short step from considerations like these to the adoption of the
+_Bacillus bulgaricus_ as the most potent of the various lactic organisms
+which have been examined, and which is likely to play such an important
+rôle in the destiny of the human race. The _Bacillus bulgaricus_ may
+claim to be the Bacillus of Long Life.
+
+
+
+
+CHAPTER III
+
+THE CHEMISTRY OF MILK
+
+
+_The Composition of Milk._—Like all other organic substances, or those
+built up in connection with the life processes of plants and animals,
+milk is of complex composition. It is also very liable to change—every
+one is acquainted with its tendency to "go bad." This instability is
+more or less inherent in all highly organised chemical compounds, and,
+indeed, it seems to be necessary that the materials used in growth and
+nutrition should be very plastic in a chemical sense, in order, _e.g._,
+that the constituents, say of a plant, may easily be transformed into
+the substances of the body of the animal which feeds on it.
+
+The perishable nature of milk—the food of young and growing animals—is
+therefore essential, so that it may be changed easily into the blood,
+bone, muscle, etc., so abundantly required in the early stages of
+existence.
+
+Milk is a complete food, and, therefore, naturally it is not a simple
+chemical compound, but a mechanical mixture of a number of substances.
+The present state of chemical knowledge on the subject does not permit
+of its composition being given in detail, but for practical purposes,
+such as those of measuring its purity and food value, this is not
+necessary.
+
+A proximate analysis, in which, at least, some of the ingredients are
+lumped together, is sufficient, and has been adopted everywhere by
+analysts. On this basis the average composition of cows' milk may be
+stated as follows:
+
+                       Per cent.
+  Water                  87.50
+  Fat                     3.50
+  Casein and albumen      3.65
+  Milk sugar              4.60
+  Ash                     0.75
+                          ────
+                        100.00
+                        ──────
+
+The constituents other than water added together form the "total
+solids," and they amount to 12.5 per cent.
+
+                       Per cent.
+  Water                  87.5
+  Total solids           12.5
+                         ────
+                        100.0
+                        ─────
+
+  [Illustration: THE CONSTITUENTS OF MILK
+  In the illustration, a pint of milk is shown in a glass
+  jar, and the various percentages of water, casein, sugar,
+  ash, albumen, and fat, which make up its constituent
+  parts, are shown in separate bottles, the percentage of
+  each being stated beneath.]
+
+Milk varies a good deal in composition; the different breeds of cows
+give varying qualities. The Short-horn gives large quantities of milk of
+rather poor analysis, while the Jersey yields smaller proportions of
+very rich milk. During the period of lactation (the time which has
+elapsed since the cow gave birth to a calf), care in milking, food,
+health, etc., all have an effect on the quality of the milk.
+
+The limits of variation may be stated as follows:
+
+                            Per cent.     Per cent.
+  Water                       87.5    to    82.5
+  Fat                          2.5     "     6.0
+  Casein and albumen           3.0     "     4.5
+  Milk sugar                   3.5     "     6.0
+  Ash                          0.6     "     0.8
+
+These figures are extreme, and it is very seldom indeed that either the
+minimum or maximum is reached. Indeed, by the regulation laid down under
+Clause 4 of the British Sale of Food and Drugs Act of 1899, when the
+percentage of solids not fat falls below 8.5 per cent., and fat under 3
+per cent., it is assumed that the milk has been adulterated. This
+regulation is a perfectly just one. While genuine milk may, in rare
+instances, show figures as low as 7.1 per cent. of solids not fat, or
+2.5 per cent. of fat, the right can hardly be claimed of supplying such
+an abnormal article to the public as milk of proper quality, and the
+dairyman who understands his business, and wishes to deal fairly with
+his customers, can, by attention to the conditions enumerated above
+which influence the composition of milk, entirely avoid the production
+of such a low-grade article.
+
+In the nutrition of both plants and animals large quantities of water
+are needed. The solids must be supplied in solution or dissolved in the
+assimilative processes, and this cannot take place without water, which
+also conveys the dissolved solids to the various parts of the economy,
+and in the case of animals removes waste materials. For the most part,
+water passes through the body unchanged, but a certain proportion unites
+chemically with the food materials and assists in their digestion. It is
+therefore not surprising that seven eighths of milk is composed of
+water. Blood contains a similar proportion, and this agreement
+emphasises the fact that milk is a perfectly balanced food.
+
+The fat of milk, which yields cream and butter, differs in some
+important respects from other fats. Like these, it is made up chiefly
+of stearin, palmitin, and olein, but, in addition, it contains an
+abnormally large proportion of compounds of certain of the volatile
+fatty acids. It is these which give to butter its agreeable flavour. By
+the methods of Duclaux, the following is the approximate composition of
+butter fat:
+
+                                              Per cent.
+  Stearin, palmitin, olein, and traces of
+     myristin and butin                         91.50
+  Butyrin                                        4.20
+  Capronin                                       2.50
+  Caprylin, caprinin, and traces of laurin       1.80
+                                                 ────
+                                               100.00
+                                               ──────
+
+Myristin occurs in nutmegs; butyrin in another combination flavours
+pineapples and rum; caprinin is found in cocoanut fat, mutton fat, and
+in the offensive odour given off by the goat (from which the name is
+derived); caprylin is a by-product of alcoholic fermentation, and also
+occurs in cocoa fat; laurin is found in sweet bay; from which it is
+evident that there are some curious relationships in flavouring
+materials.
+
+Fats are very concentrated foods, furnishing a large amount of energy to
+the body. At one time they were classed together with starch, sugar,
+and other carbohydrates as heat-producers, but the distinction which
+was drawn between the kinds of food which were thought solely to keep up
+the temperature of the organism, and those which produced force in work
+and other forms of bodily energy, has broken down, and by direct
+experiment has been found not to exist. It is usually calculated that
+one part of fat is equal in food value to about two and a quarter parts
+of any of the other carbohydrates. Milk fat or butter is more digestible
+than almost any other fat, and its importance therefore can readily be
+realised. All the above constituents of milk fat are composed of
+different proportions of carbon, hydrogen, and oxygen, but milk also
+contains minute quantities of lecithin, a fat containing phosphorus in
+addition. Lecithin is also found in the brain and nerve material of
+animals, in the yolk of egg, and in several plants.
+
+The nitrogenous constituents of milk—casein and albumen—are usually
+estimated together, and they are reckoned as of equivalent food value.
+The name protein is very commonly applied to the total of these bodies
+in milk, or other animal and vegetable foods. They are composed of
+different proportions of carbon, hydrogen, oxygen, and nitrogen, with
+small quantities of sulphur, while casein contains phosphorus in
+addition. Albumen exists to the extent of about 0.6 per cent. in milk.
+It is very similar in properties to egg albumen. The coagulum which
+forms on the surface of milk when boiled is largely composed of albumen.
+Casein is combined with, and kept in solution by, lime, soda, and
+calcium phosphate, and its amount averages a little over 3 per cent.
+
+The remarkable property possessed by rennet, of curdling or coagulating
+casein, is well known; rennet is an extract from the stomach of the
+calf, and similar principles are present in the stomachs of man and
+other animals, so that the coagulation of milk is the first process in
+its digestion. If milk is gulped down in large quantities it is apt to
+coagulate in lumps, and digestion is much interfered with, but if it is
+taken hot and slowly, it coagulates in small pieces which are readily
+attacked by the gastric juice, and milk is then one of the most
+assimilable of foods.
+
+Nature provides that the milk for young animals is supplied in finely
+divided streams, so that coagulation takes place in the best possible
+way.
+
+The proteids are the most important constituents of food; they are
+abundant in the blood, and build up the muscles, brain, nerves, and
+other bodily structures.
+
+Besides these mentioned, milk contains traces of another proteid of
+similar composition called globulin.
+
+The sugar of milk is not found anywhere else. It is a carbohydrate like
+cane and grape sugar—that is to say, the hydrogen and oxygen they
+contain are in the same relative proportions as in water. Milk sugar is
+not so soluble or so sweet as the other sugars. It does not ferment with
+ordinary yeast, but certain special yeasts which are made use of in the
+preparation of keffir, koumiss, etc., have the power of transforming it
+into alcohol. Its most remarkable property, however, is the facility
+with which, under the influence of certain bacteria, it is changed into
+lactic acid.
+
+Every one is familiar with the souring of milk, but perhaps it is not so
+generally known that there are great differences in the results obtained
+in accordance with the conditions under which the souring takes place.
+The skilled butter-maker, by keeping the milk in a cool and cleanly
+dairy, obtains a sour milk of a characteristic and agreeable aroma and
+taste, which beneficially affect the flavour of the butter produced. On
+the other hand, if milk is kept in hot and dirty surroundings, the
+development of acidity is accompanied by different bad tastes and
+odours, and it becomes unfit for use as a food. In the first case, the
+conditions are favourable to the maximum production of the lactic acid
+bacteria, and these occupy the field, and largely prevent the
+development of the other bacteria which are present—the survival of the
+fittest in the struggle for existence. In the second case, the impure
+surroundings swarm with the germs of many kinds of putrefactive
+bacteria, and the high temperature assists these to gain the upper hand.
+Again, the survival of the fittest, in the particular conditions. Even
+in cool and cleanly surroundings injurious taints may develop,
+especially if the milk has previously been subjected to a journey by
+road or rail, as is the case in the modern creamery system, where the
+farmers deliver their milk to a central creamery, where it is made into
+butter. In such establishments it is the regular practice to kill the
+germs, lactic and others, existing in the milk, by heating it to a high
+temperature. This process is called pasteurising, after the great French
+chemist and bacteriologist who invented it. Pure lactic cultures are
+added to the pasteurised milk, and the souring process is under exact
+control, with the result that butter of uniform flavour and quality is
+produced. The same method is made use of in making the special sour milk
+described in this book, with, of course, modifications in the apparatus
+employed, to suit the smaller scale in which the manufacture is
+conducted.
+
+The ash is the mineral matter which is left when milk, previously dried,
+is burnt in a crucible. It is a complex mixture, and, as we have seen,
+it amounts to about 0.7 per cent. of the milk. The process of burning
+destroys all the organic matter, and, at the same time, alters somewhat
+the state of combination of the inorganic or mineral elements. Attempts
+have been made from the analysis of the ash to reconstitute the
+composition of the mineral matter as it exists in the milk. The best
+known is that of Soldner, and the following is his calculation:
+
+                                             Per cent.
+  Sodium chloride                              10.62
+  Potassium chloride                            9.16
+  Monopotassium phosphate                      12.77
+  Dipotassium phosphates                        9.22
+  Potassium citrate                             5.47
+  Dimagnesium citrate                           3.71
+  Magnesium citrate                             4.05
+  Dicalcium phosphate                           7.42
+  Tricalcium phosphates                         8.90
+  Calcium citrate                              23.55
+  Calcium oxide, in combination with casein     5.13
+                                                ────
+                                              100.00
+                                              ──────
+
+The presence of citrates will be noted in this analysis. Citric acid,
+which gives to lemons their acidity, and is also found in other fruits,
+has been proved to exist in milk to the extent of about 0.2 per cent.
+When alkaline or earthy citrates are burnt or oxidised in the blood, the
+citric acid is destroyed, and corresponding carbonates remain. No doubt
+the function of citrates in milk is to furnish to the body the earthy
+and alkaline carbonates which are required in certain of its parts.
+
+The mineral constituents of milk have many important functions to
+perform in the building up and nutrition of the bodily organism.
+Phosphate of lime is the principal constituent of the skeleton, and the
+blood must be richly supplied with the alkalies, earths, and acids which
+are comprehended in the ash.
+
+Milk contains traces of many other substances, the most important of
+which are several enzymes which assist in its digestion.
+
+_General Properties of Milk._—The appearance of milk is known to every
+one; it ought to be a pure white opaque liquid, but very generally it is
+tinted a cream colour with anatto to give it an added appearance of
+richness. The average specific gravity is about 1.031; or, to put it
+another way, while a gallon of pure water weighs exactly 10 lbs., a
+gallon of milk weighs 10 lbs. 5 oz. It freezes at 31° F. and boils at
+about one third of a degree higher than water.
+
+When milk is examined under the microscope, the fat is found to be
+distributed through it in a multitude of minute globules varying in size
+from 1/16,000th to 1/25,000th part of an inch, and occasionally they are
+much smaller and also much larger.
+
+Fig. 1 is a micro-photograph showing the fat globules in whole milk.
+Fig. 2 is a micro-photograph of separated milk, and Fig. 3 a
+micro-photograph of cream, all under high magnification (450 diams.);
+from these figures the comparative number of fat globules present may be
+seen.
+
+  [Illustration: FIG. 1.—Micro-photograph of a Drop of
+  Whole Milk, showing distribution of fat globules.
+  (Magnified 450 diams.)]
+
+  [Illustration: FIG. 2.—Micro-photograph of Separated
+  Milk, showing the almost complete absence of fat globules
+  as compared with whole milk. (Magnified 450 diams.)]
+
+  [Illustration: FIG. 3.—Micro-photograph of Cream, showing
+  agglomeration of fat globules. (Magnified 450 diams.)]
+
+Fats distributed through a watery liquid in this finely divided
+condition form together what is called an emulsion, in which the
+particles of fat are kept apart by surface tension. The specific gravity
+of milk fat averages 0.93, and compared with water weighing 10 lbs., a
+gallon of fat would weigh 9 lbs. 5 oz. It is thus considerably
+lighter than the other constituents, and when milk is left at rest, the
+fat globules gradually rise to the top and float there, forming cream.
+The difference in specific gravity between cream and milk is taken
+advantage of in the mechanical separator, now so much used, and which
+makes such a thorough separation between the two. Cream is an article of
+the most varied composition, according to the ideas of the person who
+produces it, but it ought to contain at least 20 per cent. of butter
+fat, and may be made with a much larger percentage if necessary. When
+cream is agitated in a particular way, as by churning, the surface
+tension of the particles is overcome, and they run together into a mass
+which forms butter.
+
+The casein of milk is not held in solution in the ordinary sense, but in
+a peculiar state of suspension called the colloidal condition,
+practically the whole of it remaining behind when milk is filtered
+through clay filters.
+
+It is this state of suspension of the casein which makes milk opaque,
+but the opacity is considerably increased by the emulsified fat.
+
+The coagulation of the casein in milk by the addition of rennet has
+already been referred to. Acids, either mineral or organic, also
+precipitate it in the form of flakes. Skimmed milk is now largely used
+for the preparation of casein by this method, and the washed and dried
+precipitate is used very extensively in the arts for such varied
+purposes as the manufacture of billiard balls, paints, cements, etc.
+
+The clear liquid which separates when milk is curdled with rennet is
+called whey, and contains the milk sugar and mineral salts. The sugar is
+manufactured from it on a limited scale, and is used as an ingredient in
+infant foods, and as a convenient medium in certain medical
+preparations. In Sweden a kind of cheese is made from whey, but the
+great bulk of it everywhere is used for feeding pigs.
+
+The comparative composition of different varieties of milk is given in
+the following table:
+
+  ────────────────┬──────┬───────┬──────┬───────┬──────┬──────┬────────┬──────
+             Human│ Cow  │Buffalo│ Goat │ Sheep │ Mare │ Ass  │Reindeer│ Whale
+  ────────────────┼──────┼───────┼──────┼───────┼──────┼──────┼────────┼──────
+  Water      88.32│ 87.75│  82.57│ 86.34│ 81.08 │90.38 │90.30 │  67.7  │ 60.47
+  Fat         3.43│  3.40│   7.63│  4.25│  7.67 │ 1.00 │ 1.30 │  17.1  │ 20.00
+  Protein     1.55│  3.50│   4.69│  4.40│  6.08 │ 1.98 │ 1.80 │  10.9  │ 12.42
+  Milk Sugar  6.44│  4.60│   4.30│  4.26│  4.26 │ 6.28 │ 6.20 │   2.8  │  5.63
+  Salts       0.26│  0.75│   0.81│  0.75│  0.91 │ 0.36 │ 0.40 │   1.5  │  1.48
+  ────────────────┼──────┼───────┼──────┼───────┼──────┼──────┼────────┼──────
+  Total     100.00│100.00│ 100.00│100.00│100.00 │100.00│100.00│ 100.00 │100.00
+  ────────────────┼──────┼───────┼──────┼───────┼──────┼──────┼────────┼──────
+  Specific   1.032│1.0315│  1.033│ 1.033│ 1.038 │ 1.034│ 1.033│  ...   │  ...
+   Gravity        │      │       │      │       │      │      │        │
+  ────────────────┴──────┴───────┴──────┴───────┴──────┴──────┴────────┴──────
+
+  [Illustration: FIG. 4 is a photograph of two Petri dishes,
+  which have been inoculated with ordinary milk (A), and
+  milk that has been subjected to sterilisation (B). The
+  whitish bacterial colonies on A are due to enormous
+  numbers of organisms, while B is quite free from such
+  growth.
+
+  For the production of a reliable lactic food, it is
+  essential that certain precautions as to the treatment of
+  the milk, and the maintenance of a suitable temperature
+  during the growth of the lactic bacteria, should be
+  observed.
+
+  In the first place, milk immediately after extraction from
+  the cow contains only a few organisms, but these multiply
+  so rapidly that in a few hours the bacterial content may
+  amount to many millions per ounce. In preparing a pure
+  culture of any specific organism, then, care must be taken
+  to destroy all the bacteria that have accidentally found
+  their way into the milk, inoculating with the organisms it
+  is desired to cultivate. This is best accomplished by
+  heating the milk to the boiling-point of water for about
+  thirty minutes, by which time almost all the undesirable
+  bacteria have been killed.]
+
+The milk of the cow differs a good deal from human milk, and where the
+former is used for the feeding of children it is usual to add milk sugar
+to it, and otherwise alter it to bring its composition more in harmony
+with the human article. The high concentration of the milk of the
+reindeer and the whale is noteworthy. Perhaps this may be due to the low
+temperature conditions in which these animals live, necessitating strong
+nutriment to enable their young to make proper progress in growth and
+development. On the other hand, the milk of the ass is poor in quality,
+and probably on this account it is more readily assimilated by those of
+weak digestion, to whom it is sometimes recommended. Goats' milk is
+richer than either cow or human milk, and its nourishing properties are
+well known. The goat is usually free from tuberculosis and other
+diseases which affect the cow, and its milk is therefore a very safe
+article to use.
+
+_The Analysis of Milk._—While the analysis of milk can only be made by
+a competent chemist, there are a number of simple tests and observations
+by which any intelligent person can obtain a fair idea of its quality.
+The taste and smell afford some guide, as also the general appearance.
+To judge of the latter, place some of the milk in a tumbler or other
+clear glass vessel. If the milk is of good quality it will be quite
+homogeneous and opaque. Any flocculent matter indicates either disease
+in the cow or that the milk is old and bacteria have multiplied in it
+and altered its composition. When the milk has stood long enough for the
+cream to rise freely, the latter should form a perfectly homogeneous and
+strongly defined layer on the top. The quantity of cream may be measured
+in a creamometer, which consists of a small glass cylinder graduated at
+the top (Fig. 5). It is filled with milk to the top graduation line, and
+when the cream has risen, the percentage quantity of the latter which
+has separated can be taken off.
+
+  [Illustration: FIG. 5. The Creamometer]
+
+The colour should be like that of porcelain, but, as already stated, it
+is a common thing for the dairyman to add a small quantity of anatto or
+an aniline dye of a similar shade, to give the milk a rich creamy tint.
+If the milk is of a reddish colour this may be caused by blood from the
+udder, although certain foods, such as beets, mangels, and carrots
+sometimes give a similar tint. The milk given by cows immediately after
+calving is called "colostrum" or "biestings," and is of a yellow or
+yellow-brown colour. It is much thicker than ordinary milk, and
+coagulates in boiling.
+
+In dirty byres in which care is not taken in milking, quite considerable
+quantities of hairs, pieces of manure, and other filth may get into the
+milk. Usually the milk is strained by the dairyman, but sometimes this
+is omitted or carelessly done. To test for dirt, a ribbed glass funnel
+is useful. Get a piece of the finest muslin about twice the diameter of
+the funnel, fold over twice, so that it becomes one quarter of its
+original size; open one of the sections and place in the funnel; pass
+the milk into this. It will run through quickly and some water may be
+run into the funnel to clear away the last traces of milk. The filter
+cloth can then be opened out and any dirt retained will become visible.
+The apparatus is shown in Fig. 6.
+
+  [Illustration: TESTING-GLASS FOR EXTRANEOUS MATTER IN
+  MILK.
+
+  FIG. 6.—A piece of muslin is folded as shown and a
+  measured quantity of milk is passed through the funnel;
+  from the sediment left in the muslin, the percentage of
+  extraneous matter may be arrived at.]
+
+If a glass funnel is not available, a very small jelly bag can be made
+of fine gauze and used in the same way. The washing water should be used
+in small quantities and directed to concentrating the dirt in the apex
+of the bag. After washing, the latter can be turned outside in, to
+permit of readier examination of the dirt. The bag should be well
+washed in cold water, then boiled and dried, and is then ready for
+future use.
+
+The acidity of milk is a very useful guide to its age. Milk has the
+curious property of being "amphoteric," _i.e._, it is both slightly acid
+and slightly alkaline when fresh. As its age increases, however, so does
+its acidity, and at a rate varying with the temperature and moisture
+contents of the atmosphere in which it is placed. Old and acid milk is
+heavily contaminated with bacteria, a proportion of which are likely to
+be injurious to health.
+
+  [Illustration: FIG. 7. Lactometer and Test Tube]
+
+The simplest method of testing the acidity is to procure a few little
+books of blue and red litmus test papers, and these can be had from any
+philosophical instrument maker or laboratory furnisher. The strips of
+test paper are torn out and dipped in the milk. When the milk is quite
+fresh it will, owing to its amphoteric condition, change the red litmus
+paper slightly blue, and the blue litmus paper slightly red. Old milk
+changes blue litmus paper to a bright red because of its decided
+acidity.
+
+The above tests do not indicate if the milk is poor or rich, but this
+can be determined by the lactometer, an instrument for ascertaining in a
+simple way the specific gravity. The lactometer is shown in Fig. 7.
+
+It is graduated usually from 25° to 36°, corresponding to specific
+gravities 1.029 to 1.038. It is graduated to degrees and half degrees.
+Sometimes a thermometer is combined with the instrument. The specific
+gravity rises as the temperature is lowered and decreases with increase
+of temperature, so that it is important to make the test at the figure
+at which the lactometer was graduated, which is usually 60° F. Failing
+this, an allowance has to be made for higher or lower temperatures. The
+milk to be tested is well mixed, and placed in a deep vessel, and the
+lactometer placed in it, holding it at first at an angle. It stands
+upright and remains deeper or higher according to the specific gravity.
+The reading is taken on the stem at the level of the milk. As the latter
+is drawn up a little round the stem, about a half degree should be added
+on to get the true figure. Thus, if the apparent reading is 31, the true
+reading may be taken as 31.5. This is the average figure for good milk,
+corresponding to a specific gravity of 1.0315; anything above this is
+all to the good. Lower readings mean inferior quality, the latter being
+proportionate to the lowness of the readings. The tests are most
+conveniently made in a glass cylinder (Fig. 7), which may be purchased
+with the lactometer. As there are many inaccurate instruments in the
+market, it is necessary to go to a reputable maker, because an
+unreliable lactometer is worse than useless.
+
+The following table gives, in a condensed form, the allowances to be
+made when the temperature is above or below the standard (60° F.):
+
+  ────────────┬──────────────────────────────────────────────────────────
+  Temperature.│               Reading of Lactometer.
+  ────────────┼─────┬────┬────┬────┬────┬────┬────┬────┬────┬────┬────┬────
+     Degs. F. │     │    │    │    │    │    │    │    │    │    │    │
+       40     │ 23.5│24.5│25.5│26.4│27.3│28.2│29.1│30.0│31.0│31.9│32.8│33.7
+       45     │ 23.8│24.8│25.9│26.8│27.8│28.6│29.3│30.4│31.3│32.3│33.2│34.2
+       50     │ 24.1│25.1│26.1│27.0│28.0│29.0│29.9│30.9│31.8│32.8│33.7│34.7
+       55     │ 24.5│25.5│26.5│27.5│28.5│29.5│30.4│31.4│32.4│33.4│34.3│35.3
+  ────────────┼─────┼────┼────┼────┼────┼────┼────┼────┼────┼────┼────┼────
+       60     │ 25.0│26.0│27.0│28.0│29.0│30.0│31.0│32.0│33.0│34.0│35.0│36.0
+  ────────────┼─────┼────┼────┼────┼────┼────┼────┼────┼────┼────┼────┼────
+       65     │ 25.5│26.6│27.6│28.7│29.6│30.7│31.7│32.8│33.8│34.8│35.8│ ...
+       70     │ 26.1│27.2│28.2│29.3│30.2│31.3│32.4│33.4│34.5│35.5│36.5│ ...
+       75     │ 26.8│27.8│28.8│29.9│30.8│32.1│33.1│34.2│35.2│36.3│ ...│ ...
+       80     │ 27.4│28.4│29.5│30.7│31.6│32.8│33.9│35.9 36.1│ ...│ ...│ ...
+  ────────────┴─────┴────┴────┴────┴────┴────┴────┴────┴────┴────┴────┴────
+
+Thus if the thermometer indicates 40° F., and the lactometer 29.1°, the
+true reading at the standard temperature of 60° F. is 31°, corresponding
+to a specific gravity of 1.031. Intermediate figures can readily be
+averaged. Care should be taken to wash the lactometer with cold water
+under the tap, as otherwise the milk will dry on it and render it
+inaccurate.
+
+
+
+
+CHAPTER IV
+
+HANDLING OF MILK
+
+
+MODERN DAIRY PRACTICE
+
+As we have seen, the dairy industry is a very ancient one, and has been
+intimately associated with the development of civilisation.
+
+Within historical times dairying has always formed a prominent feature
+in connection with agriculture, and the use of milk in one form or
+another has been common to every civilised nation.[42]
+
+The greatest progress, however, in the study of milk has taken place
+since about the year 1890, at which time the dairy industry seems to
+have attracted the general attention of food specialists and scientific
+investigators throughout the world. Since then it has been considered
+worth while to enact laws in different countries with regard to the
+regulation and control of the milk supply.
+
+Since 1903 there has been an International Dairy Federation formed, and
+it has held conferences at Brussels, Paris, The Hague, and Buda-Pest,
+and in 1911 it will hold a conference in Stockholm. The Federation was
+started in a very humble way in Brussels, and owes its origin, to a
+large extent, to a distinguished Belgian agriculturist, Baron Peers of
+Oostcamp, Bruges; but at the present day a general committee composed of
+representatives of nearly every civilised nation has been formed, and
+delegates from such countries attend the Congresses, which are held
+every two years. The literature which has arisen out of these
+International Congresses has been disseminated in different countries,
+and has been instrumental in placing the dairy industry on a thoroughly
+scientific basis.
+
+_Milk Supply of the United Kingdom._—The milk supply of the United
+Kingdom has steadily grown from year to year, and in relation to the
+population works out at fifteen gallons per head. The manner in which
+these figures are arrived at is shown in the following estimate:
+
+  The population of the United Kingdom is now about
+  45,500,000. The number of cows or heifers in calf or in
+  milk in June, 1909, was 3,360,600; the number in 1910 was
+  probably about 4,400,000.
+
+  Of these about 300,000 were heifers that had not yet
+  produced any milk. The actual milking class, therefore,
+  comprised about 4,100,000 cows and heifers; of these,
+  about 600,000 were heifers that calved in the winter and
+  spring of 1909-10, and 300,000 were heifers that calved in
+  the summer and autumn of 1910. The number of cows that
+  produced two or more calves may be taken to be about
+  3,200,000; of these about 600,000 should have produced
+  their second calf in the winter and spring 1909-10, and
+  would be milked as heifers in the summer and autumn of
+  1910; the number of mature cows from which a full season's
+  supply of milk was obtained during the twelve months from
+  June 5, 1909, to June 4, 1910, was apparently about
+  2,600,000. A large quantity of milk is yielded during the
+  year by cows sold or lost during the twelve months before
+  the census. Possibly ten per cent. of the milk produced in
+  the twelve months from June, 1909, to June, 1910, was
+  yielded by cows that were sold or lost before the census
+  of June, 1910.
+
+  It is estimated that the 3,200,000 cows (including the
+  600,000 that up to the winter of 1909-10 were heifers)
+  produced, on the average, 44 cwts. (480 gallons) of milk
+  per head in the twelve months from June 5, 1909, to June
+  4, 1910; the 300,000 heifers that calved in the summer and
+  autumn, 30 cwts. (330 gallons) per head; the 600,000
+  heifers that calved in the winter and spring of 1909-10,
+  15 cwts. (165 gallons), making the total quantity of milk
+  produced in the twelve months by cows and heifers on the
+  farms, and that produced calves during the twelve months
+  (June, 1909-1910), 158,800,000 cwts. (1,746,800,000
+  gallons), or about 426 gallons per head, and about 400
+  gallons per head for all the cows and heifers in milk or
+  in calf in 1910. There remains to add the milk yielded by
+  the cows that were sold during the twelve months, and of
+  cows and heifers in feeding pastures that were milked
+  during the twelve months, June to June, 1909-10, and which
+  probably formed one tenth of the whole supply, making the
+  total supply for the twelve months 176,444,000 cwts., or
+  1,940,884,000 gallons. This equals 2 tons, or 440 gallons
+  per head, crediting the whole supply to the 4,400,000 cows
+  and heifers in milk or in calf in June, 1910. At 7-1/4d.
+  per gallon the value of milk produced in the United
+  Kingdom in the twelve months was £58,600,000. Including
+  the value at birth of the calves, the total value of the
+  produce of the milk-giving class would be about
+  £62,000,000. The value of the milk, butter, cheese, and
+  cream sold or consumed in farmhouses would be about
+  £48,000,000, or equal to about 24 per cent. of the gross
+  annual income of farmers.
+
+  The average consumption of new milk is about 15 gallons
+  per head of the population. During the twelve months of
+  1911, the quantity required for this purpose will be about
+  682,500,000 gallons, or about 35 per cent. of the total
+  supply; calves will require about 10 per cent. of the
+  supply; the quantity available for butter and cheese will
+  equal about 55 per cent. of the supply.[43]
+
+_The Milk Industry in the United States._—In the United States of
+America, where the habits of the people are somewhat analogous to those
+in the United Kingdom, it is estimated that the milk from five million
+cows is annually consumed, which averages twenty-five and one half
+gallons per year for each person, or equal to an ordinary sized
+tumblerful each day.[44]
+
+Such a vast industry, so intimately associated with the food of the bulk
+of the people, naturally invites the closest study, and, as a
+consequence, the literature on the subject, which has arisen during the
+last twenty years, has been of a voluminous character, not only from the
+point of view of practice, but from that of bacteriology, chemistry, and
+hygiene.
+
+A pure milk supply is essential to health, and it seems unfortunate that
+the ordinary milk producer should, in a great many cases, take up an
+antagonistic attitude to the scientific methods of handling milk. There
+is a body of opinion being created, however, which is likely to alter
+this attitude in the next generation, and this is attributable to the
+fact that so much excellent work has been done at numerous dairy
+colleges and institutes in all civilised countries that the dairy
+industry is emerging from a period of rule-of-thumb procedure to its
+proper place as one of the technical arts.
+
+_Transmission of Disease in Milk._—It is not to be wondered at that the
+handling of milk should now be regarded as a technical business, seeing
+that milk-borne disease is one of the commonest with which we have to
+deal.
+
+The commoner diseases which have been transmitted by milk are scarlet
+fever, typhoid, diphtheria, tuberculosis, sore throat epidemics. Others
+of a more complex character have been traced to the same source of
+infection, and the clearest possible evidence has been furnished of the
+transmission of diseases by means of micro-organisms, which have
+contaminated the milk supply.
+
+It is therefore necessary to watch over the milk from the source of
+supply to its consumption. It is primarily on the farm and in the
+cow-house that methods of handling in a hygienic way should be insisted
+on, as microbial contamination increases at a prodigious rate, and it is
+the early microbe therefore which does the most damage.
+
+The milk in the udder, for all practical purposes, may be assumed to be
+sterile, and the contamination which takes place originates, therefore,
+from external sources.
+
+One of the principal means of infection is from hairs which fall from
+the cow into the milk, and many of which are carriers of dangerous
+micro-organisms.
+
+There is also a certain amount of offensive dirty matter which may fall
+into the milk-pail, and carry with it undesirable germs.
+
+These impurities may, to a certain extent, be eliminated by good
+straining, but a surer prevention is to have the cow-house perfectly
+clean and free from dust, as dust specks are in many cases the vehicles
+of disease germs. Cleanliness is, in fact, the essential feature in
+modern dairying, not only in the cow-house, but in the milking utensils,
+the drainage, etc., and, above all, the milker should be of cleanly
+habits.
+
+The flavours of milk sometimes arise from the absorption of
+evil-smelling gases in the cow-house, or from a peculiar taint from
+certain roots and feeding stuffs, and in such a case it is desirable
+that aëration should take place in a fresh clear atmosphere, so that
+oxygenation may have the effect of eliminating and destroying the
+foreign odours and flavours which may be present. If this process of
+aëration is carried out at blood heat, the result is generally highly
+satisfactory.
+
+_Milk Management._—There have been many excellent tables of rules
+published for the management of dairies in different countries, but they
+are necessarily framed within certain limitations which apply to all.
+The following is an excellent set, which put concisely the conditions
+necessary to be observed in the modern cow-house:
+
+   1. The cow should be sound—no disease should exist in
+        the animal.
+
+   2. The feed should be good and free from aromatic
+        substances. If these aromatic foods are used, they should
+        be employed according to those methods which will not
+        cause odours or flavours to appear in the milk.
+
+   3. The cow should be groomed, and hair about the udder
+        preferably clipped.
+
+   4. The udder should be moistened during milking.
+
+   5. The milker should be a neat, tidy person.
+
+   6. The milker should be free from disease, and should not
+        come in contact with any communicable disease.
+
+   7. The milker's clothes and hands should be clean while
+        milking.
+
+   8. The pail should be sterilised.
+
+   9. The stall should be such as to reduce the amount of
+        disturbance of dust and dirt.
+
+  10. There should be good light, good ventilation, and
+         good drainage in the cow-house.
+
+  11. The cow-house should always be kept clean.
+
+  12. Feeding and bedding, unless moist, should be done
+        after milking.
+
+  13. A dustless milking-room is desirable.
+
+  14. Milk should not stand in the cow-house.
+
+  15. If milk is aërated, it should be done before cooling
+        and in pure air.
+
+  16. The sooner the milk is cooled after milking the
+        better.
+
+  17. Keep the milk as cold as possible when once
+        cooled.[45]
+
+The supply of milk is conducted, to a large extent, by towns' dairies,
+which depend for their supplies upon the dairy farm in the country, and
+it is obvious that a certain period of time must elapse, in the
+generality of cases, before a town's dairy receives its supply in the
+ordinary course, and this constitutes the greatest difficulty in modern
+dairy practice, owing to the liability of the milk to absorb bacteria,
+which during transit may multiply enormously.
+
+The multiplying of bacteria in milk at different temperatures is easily
+demonstrated, and the result of this has been stated in various forms
+many times over. As a graphic means, however, of showing the increase
+that takes place in the numbers of germs present, and the consequent
+product of acidity, the table below by Conn may be given.
+
+The consequent result of the increase in bacteria is the production of
+lactic acid, which produces the souring so familiar in milk which has
+been kept in the household at a high temperature.
+
+  _Numbers of Bacteria per c.cm. in Milk kept at
+             Different Temperatures._
+
+  ──────┬───────┬───────┬─────────┬─────────────────────┬──────────┬──────────
+  Number│  In 12│  In 12│   In 50 │  In 50 hrs. or at   │ No. hrs. │ No. hrs.
+  at    │hrs. at│hrs. at│ hrs. at │ time of curdling    │to curdle │to curdle
+  Outset│ 50° F.│ 70° F.│  50° F. │ at 70° F.           │ at 50° F.│ at 70° F.
+  ──────┼───────┼───────┼─────────┼─────────────────────┼──────────┼──────────
+  46,000│ 39,000│249,500│1,500,000│  542,000,000        │   190    │   56
+  47,000│ 44,800│360,000│  127,500│  792,000,000.36 hrs.│   289    │   36
+  50,000│ 35,000 800,000│  160,000│2,560,000,000.42 hrs.│   172    │   42
+  ──────┴───────┴───────┴─────────┴─────────────────────┴──────────┴──────────
+
+What actually happens is that the lactic acid is produced by the
+breaking up of the milk sugar, and the appearance of this sourness is an
+indication that a period has been reached in the age of the milk which
+may be described as being—unwholesome.[46]
+
+It is necessary, therefore, for the town's milk dairy to be equipped in
+such a way as to deal promptly with the milk supply.
+
+We have seen that the milk should first of all be aërated at blood heat,
+so as to liberate objectionable odours, after which it should be cooled
+to as low a temperature as possible, by means of well water. When these
+operations have been performed on the farm, milk should be sent as
+rapidly as possible to the distributing towns' dairies, and should be
+transported in refrigerated waggons, cooled preferably with ice, during
+the journey. On arrival at the town dairy, it will be necessary to
+pasteurise the milk—that is to say, the milk should be heated to such a
+temperature as will destroy any pathogenic organisms which may be
+present, and the pasteurising temperature should therefore be in excess
+of the thermal death-point of all such organisms.
+
+Pasteurisation owes its origin to Pasteur, and has become an adopted
+method throughout the dairy industry, and there are many mechanical
+devices termed "pasteurisers" (see Fig. 8) which are used for the
+carrying out of this particular operation. The form of one of these is
+that of a vertical jacketed cylinder with paraboloidal surface, around
+which steam is made to pass, so as to maintain the temperature at about
+176° F. Milk is allowed to flow in at the bottom of the paraboloidal
+surface, and is caught by mechanical agitating arms, which revolve at a
+given speed, and by this action milk is distributed centrifugally over
+the paraboloidal surface, and is forced out by the same action, at the
+top of the apparatus, after being heated.
+
+  [Illustration: PASTEURISER
+
+  FIG. 8.—The milk enters from the bottom and circulates to
+  the top of the inside cylinder, which is paraboloidal in
+  construction. It is heated as it passes through the
+  apparatus, and is discharged at the top at a temperature
+  of 176° F.]
+
+The centrifugal action is sufficient to raise the milk some three to
+four feet, through a tube, and this is taken advantage of so as to cause
+the milk to flow over a conical cooler, described as a primary cooler,
+and in which water is made to circulate. As the hot milk descends over
+the conical cooler it gives up most of its acquired heat to the water,
+and, in practice, is reduced in temperature to within 4° of the
+temperature of the water.
+
+Below this primary cooler is fixed a cooler of the same size and shape,
+which is termed a secondary cooler. In it, brine at a temperature of
+about 35° F. is circulated from a refrigerating machine, and, as the
+milk falls over the secondary cooler, it is cooled to a temperature of
+about 40° F., when it may be looked upon as being pasteurised and free
+from all pathogenic organisms, in which state it will keep for a
+considerable length of time.
+
+It is desirable that the milk should, as soon as possible after the
+cooling takes place, be delivered to the consumers, and be kept under
+cool conditions, either in bottles or in a closed vessel covered over
+with muslin, so as to keep out specks of germ-laden dust.
+
+Briefly speaking, the foregoing is an outline of what is carried on in
+the ordinary dairy practice.
+
+There are many modifications of this practice, such as the introduction
+of regenerative heaters, so as to utilise a portion of the heat of
+pasteurisation, which would otherwise be wasted.
+
+In some cases, again, it is considered necessary to conduct the primary
+and secondary cooling over coolers furnished with mantles, so that the
+atmospheric bacteria which are everywhere present should be shut off
+from the falling milk.
+
+Ordinarily, however, the equipment for a town's dairy consists of:
+
+1. Steam-boiler to generate steam for pasteurising, scalding, etc.
+
+2. Motive power, which may be either a steam-engine, gas-engine, or
+electric motor.
+
+3. Refrigerating machine, which is used for supplying cold brine to the
+secondary cooler. In many cases it is also used for cooling a room in
+which the milk and cream are stored.
+
+4. Milk-receiving tank.
+
+5. Milk-strainer.
+
+6. Pasteurising apparatus, and primary and secondary coolers.
+
+Such a plant is necessary in order to conduct an ordinary town dairy
+business in anything like a hygienic way, and is designed only for the
+handling of milk intended for domestic consumption.
+
+There are times when another plant might be necessary, such as a plant
+for the separation of milk, or for utilising it for the production of
+butter or cheese, such operations being subject to the fluctuations in
+the milk supply.
+
+It is sometimes desirable also to use up an excess of milk for cheese or
+butter-making; hence it is necessary to provide such apparatus as has
+been indicated.
+
+_Preparation of Soured Milk._—The foregoing description has been given
+in some detail, as showing the ordinary practice, and we now come to
+consider how it can be modified so as to provide for the production of
+soured milk. It may first of all be premised that within the next few
+years the preparation of soured milk as an ordinary production of the
+dairy will be universal, and will form a part of the ordinary dairy
+practice. The apparatus, therefore, which is necessary is one of
+considerable interest to all who are engaged in the dairy industry.
+
+As will be seen from the chapter describing the preparation of soured
+milk in the dairy, this process can be conveniently carried on, so as to
+utilise the plant which is at present in general use. The milk can be
+received in the same way, pasteurised and cooled to about blood-heat,
+after which its preparation as soured milk is a very simple matter, and
+only requires a certain amount of careful attention.
+
+For the keeping of soured milk, a cold room cooled by a refrigerating
+machine would be desirable, so as to maintain the fermented milk at a
+low temperature and prevent over-fermentation.
+
+Apparatus has been designed so as to handle soured milk on a large
+scale, and one of the machines is shown on the illustration (see Fig.
+9). It is simply a jacketed cylinder with a cover and an agitating gear.
+The inside of the machine is nickel-plated, and there is an arrangement
+whereby the cooling may be done rapidly, through a coil inside the
+jacket, this coil being connected to the brine circulation of the
+refrigerating machine.
+
+  [Illustration: CONTINUOUS APPARATUS FOR THE PRODUCTION OF
+  LARGE QUANTITIES OF SOURED MILK
+
+  FIG. 9—This apparatus is made by the Dairy Machinery and
+  Construction Company of Shelton, Conn., U S A. The milk is
+  agitated inside a jacketed cylinder, where it is allowed
+  to incubate at about blood heat. The milk can be rapidly
+  heated and also rapidly cooled by means of this
+  apparatus.]
+
+The machine is filled with milk containing three per cent. of fat, which
+has been previously pasteurised to about 190° F., and cooled down to
+about 90° F.; at this point the pure culture of _Bacillus bulgaricus_ is
+introduced, and the agitator is kept working, so as to mingle it
+thoroughly with the milk. The agitator is then stopped until the acidity
+shows a test of 0.9 to 1.0 per cent., when the agitator is again
+started, and cold brine from the refrigerating machine is turned on to
+the cooling pipes, so that the product is thoroughly broken up, and
+cooled down to 40° F.
+
+The milk is then transferred to a bottle-filling machine (Fig. 10),
+poured into bottles and hermetically sealed, after which it is ready for
+consumption. When it has to be kept for any time it should be placed
+in a cold room where there is a temperature not higher than 40° F.
+
+The process, therefore, is a simple one, and lends itself to the
+ordinary dairy business, without involving any great expenditure on
+account of a new plant.
+
+
+
+
+CHAPTER V
+
+THE BACTERIOLOGY OF FERMENTED OR SOURED MILK
+
+
+A CHAPTER FOR STUDENTS
+
+During the last few years much work has been done in investigating the
+action of various classes of organisms—bacteria, yeasts, and
+moulds—upon milk and its products. While, however, the attention of the
+dairyman has been chiefly directed to the propagation of acid-producing
+organisms and the use of pure cultures of lactic acid bacteria in their
+relation to butter and cheese making, a new sphere in micro-biology has
+been disclosed by the study of the effects caused by the combined growth
+of two or more different classes of organisms in milk and the consequent
+production of lactic, alcoholic, and gaseous fermentations. The
+simultaneous occurrence of these fermentative changes is responsible for
+the formation of such beverages as keffir, koumiss, milk-wine, etc. It
+has therefore become essential, in connection with the study of new
+developments in the milk industry, that we should make a more intimate
+acquaintance with the bacteriology of the ferments involved.
+
+_Keffir_ (_kephir_, _kifyr_, _kiafyr_, _kephor_, _kyppe_) is the name
+given to an acid, slightly alcoholic drink, which for many centuries has
+been prepared by the nomadic tribes in the Caucasus. The characteristic
+fermentation is induced by the addition of so-called keffir grains.
+These are yellow or golden-yellow, warty, and furrowed flakes or
+nodules, the former varying in size from that of a rice grain to that of
+a bean, while the latter are often about an inch across and one eighth
+of an inch thick. Bearing in mind the fact that the preparation of
+keffir has been carried on for many centuries, it is not surprising that
+the origin of these grains should be surrounded by myths.
+
+The belief is prevalent among the Mohammedan tribes of the Caucasus that
+keffir grains were, in the first instance, presented by Allah, as a sign
+of immortality, to one preferred tribe. Others hold that, in past ages,
+they were found by shepherds growing on a shrub in the Caucasian
+highlands; while, according to Skolotowski,[47] they were originally
+found adhering to the walls of an oaken vessel used for the preparation
+of airam. This is a soured milk beverage similar to keffir, but
+possessing a weaker alcoholic fermentation, and prepared from goats'
+milk by the addition of pieces of calf's stomach. This would undoubtedly
+serve to introduce various species of lactic acid bacteria, and will be
+referred to in the portion dealing with soured milks. Keffir is prepared
+by the Caucasians from cows', sheep's, or goats' milk, and the operation
+is carried on in large leathern tubes or bottles. After the addition of
+the grains or seeds to the milk the vessel is placed in a cool chamber,
+and the fermentation is allowed to proceed for one or two days, by the
+end of which time the normal fermentation is at an end. During this
+period the keffir grains have increased enormously in size, assume a
+bright yellow colour, and lose their sour buttery smell.
+
+Previous to the removal of the fermented liquid, a portion of the bottle
+is firmly bound from the rest by a stout cord, and the greater portion
+of the remaining keffir is quickly removed for use, thus avoiding, as
+far as practicable, any outside infection. After the addition of fresh
+warm milk the cord round the end of the bottle is removed, and the old
+and new milk thoroughly mixed for a time in order to ensure uniform
+inoculation of the new milk for the next fermentation. During the winter
+months the leathern vessels are often placed in the sunshine, so that
+the temperature remains at 61° to 65° F.
+
+The necessary agitation of the vessel is said to be supplied in the form
+of kicks by passers-by or by the children during their play.
+
+The beverage prepared in this way is so gaseous in character that it is
+often blown forcibly from the vessel during removal, and possesses,
+according to Podowyssozki,[48] a very acid taste.
+
+During any interruption in the preparation of keffir in the above
+manner, the grains are taken out, and after having been well washed in
+clean water, are spread out on a clean cloth to dry in the sunshine.
+They thereby assume a characteristic cheesy or buttery odour and become
+rather darker in colour. Thorough desiccation is essential in order to
+prevent subsequent mouldiness or disease of the grain.
+
+In European countries the grains are subjected to a preliminary soaking
+in water for five to six hours and then placed in four to five changes
+of milk, each change having a duration of two to three hours. As soon as
+the grains commence to rise to the surface of the milk, they may be used
+for the actual preparation. To this end, a small quantity of the grain
+is added to freshly boiled milk and allowed to stand for eight to twelve
+hours at a temperature of 55°-62° F. with agitation of the flask every
+two hours. By this time the milk, now known as Sakwaska, has become
+abundantly inoculated with the organisms essential to the fermentation,
+and after the removal of the grains, may be poured into well-corked
+flasks for the secondary brew. The flasks should be kept at a lower
+temperature for twenty-four to forty-eight hours, by which time the
+product is ready for consumption.
+
+According to the temperature and length of period to which this
+subsequent fermentation is allowed to proceed, the resultant keffir is
+more or less acid and gaseous. The grains may again be used for starting
+a fresh portion of milk, and a regular supply obtained in this manner.
+Well-fermented forty-eight-hours-old keffir should be an effervescent
+beverage with prickling and acid taste and a consistency and smell
+similar to sour cream. Large, persistent bubbles should form on the
+surface of the liquid and the casein be present as an extremely fine
+flocculent precipitate which remains suspended for a considerable time.
+
+From the third day there ensues a gradual peptonisation of the casein.
+If the temperature at which the secondary fermentation has occurred
+should be higher than 72° F., or if the milk has not been sufficiently
+agitated, then the casein will be present in the form of porous small
+flakes, which on shaking form a fine emulsion.
+
+The chemical changes undergone by the milk during the preparation of
+keffir are confined almost exclusively to the milk sugar. As already
+stated, a slight peptonisation occurs in old samples, but this depends
+very largely upon the method of preparation and purity of the culture.
+Hammersten[49] and Essaulow[50] show, however, that this is not a
+concomitant of normal fermentation. According to Hammersten, normal
+keffir contains—
+
+                            Per cent.
+  Water                       88.26
+  Fat                          3.35
+  Casein                       2.98
+  Lactalbumen                  0.28
+  Peptones                     0.05
+  Milk sugar                   2.78
+  Lactic acid                  0.81
+  Alcohol                      0.70
+  Ash                          0.79
+
+In no case should the acid be higher than 1.0 per cent., and the alcohol
+more than 0.75 per cent.
+
+_Biology of the Keffir Grain._—The first communication on the biology
+of the keffir grain seems to have been made by Kern.[51] He regarded the
+grain as a zoöglœa composed of bacilli and yeasts, the latter being
+regarded as the ordinary beer yeast (_Saccharomyces cerevisseæ_), while
+to the former he gave the name of _Dispora caucasica_. As the name
+indicates, this bacillus possesses two polar spores, and germination of
+these proceeded in the same manner as with _Bac. subtilis_. As, however,
+pure cultures of the organisms were not made, and the descriptions and
+illustrations made by Kern fail to show any distinctive characteristics,
+it seems probable that accidental confusion with other organisms must
+have occurred.
+
+  [Illustration: A MILK FILLING APPARATUS
+
+  FIG. 10—Where soured milk is handled on the large scale,
+  a special filling apparatus for bottles is desirable, and
+  the soured milk supply should be under cover as shown.
+  This apparatus is made by the Dairy Machinery and
+  Construction Company.]
+
+Krannhals[52] succeeded in isolating ten different keffir bacteria among
+which were several sporulating bacteria. Here too it is impossible to
+attach any importance to the results, as the artificial preparation of
+keffir, by means of these bacteria, was not attempted. Beijerinck[53]
+studied the organisms constituting keffir grains and attached prime
+importance to the occurrence of two organisms, viz., (_a_) a yeast,
+_Saccharomyces kefir_, which was capable of inverting milk sugar by
+means of an enzyme (lactase) and afterwards fermented the products with
+the formation of alcohol and carbon dioxide, and also (_b_) a non-motile
+non-sporulating bacterium, afterwards _Lactobac. caucasicus_. The
+latter, when cultivated on gelatine, gave rise to tough warty colonies
+about 1/40 in. diameter, and was regarded as one of the lactic acid
+bacteria found in milk which has been incubated at 77° to 90° F. and
+afterwards incubated at a higher temperature, 100° to 104° F. Scholl[54]
+isolated three different organisms, of which a yeast inverted milk sugar
+for the lactic acid bacteria, while _Dispora_ peptonised the albuminoid
+matters.
+
+Adametz[55] failed to isolate _Dispora_, and came to the conclusion
+that ordinary lactic bacteria and yeasts played the most important part
+in the fermentation.
+
+Essaulow found in keffir grains six different organisms—yeast cells,
+cocci, short thick bacilli, bent bacilli, long threads, and motile
+bacteria. The two latter would seem to be _Bacillus subtilis_, while the
+others may be regarded as _Bacterium acidi lactici_ (Hueppe), _Bacterium
+aërogenes_, and _Streptococcus lacticus_ (Grotenfeldt). Pure cultures
+were insufficient to produce keffir, while mixed cultures of _Bacterium
+acidi lactici_ and yeasts were effective.
+
+Freudenreich,[56] to whom we owe a record of very carefully executed
+experiments, could not arrive at a satisfactory explanation of the rôle
+of _Bacillus caucasicus_. This organism is described as being 5-6 µ long
+and 1 µ thick, slightly motile, and possessing bright refractive spots
+at the poles of the bacilli. It is extremely difficult to cultivate, and
+forms flat, small greyish colonies of irregular outline. The bright
+refractive spots above referred to are, however, granules taking the
+usual stains quite readily, and not spores as supposed by Kern.
+
+Freudenreich also found three other organisms—a yeast and two
+streptococci. The yeast, to which he gave the name _Saccharomyces_
+(Torula) _keffir_, forms small oval or roundish cells 2-3 µ wide and 3-5
+µ long. The optimum temperature would seem to be about 72° F.; the
+maximum 82° F. This organism is unable to ferment milk directly, but is
+able to decompose maltose and glucose with gas production. It does not
+coagulate milk, but imparts to it a characteristic taste and is unable
+to withstand desiccation for more than a few days.
+
+Of the two streptococci isolated, _Streptococcus a_ resembles organisms
+of the group _Streptococcus lacticus_ in appearance, but is able to
+ferment milk, with weak acid and gas production, and is capable of
+inducing coagulation.
+
+  [Illustration: FIG. 11.—Section through a Kephir
+  Grain—highly magnified.]
+
+Contrary to what one would expect in an organism existing in keffir
+grains, this streptococcus is as little able to withstand desiccation as
+the above-mentioned yeast. _Streptococcus b_ forms smaller cells as well
+as smaller colonies than _Streptococcus a_, but produces more lactic
+acid and more gas, and retains its vitality after desiccation. The
+relation of these four organisms is, according to E. von Freudenreich,
+as follows: _Sacch. keffir_ is unable to ferment directly milk or
+lactose, so that its growth must be preceded by that of _Streptococcus
+b_. _Streptococcus a_ does not seem to play this part, but, unlike
+_Streptococcus b_, is able to coagulate milk on its own account. By the
+combined action of the yeast and the two streptococci, then, milk can be
+coagulated, milk sugar inverted, acid and gas produced by the
+streptococci, while gas and alcohol are formed by the activity of the
+yeast. The rôle of _Bacillus caucasicus_ is unknown, but it would seem
+to play a part in the formation of the keffir grain itself. By means of
+mixed cultures of the above organisms Freudenreich was successful in
+obtaining a fermented product possessing in all respects the
+characteristic properties of normal keffir. On the other hand,
+experiments to induce the formation of keffir grains gave negative
+results, but in this respect the cultural characteristics of
+_Lactobacillus keffir_ would seem to give promise of success in the
+synthesis of the keffir grain. Fig. 11 is a photo-micrograph of an
+extremely thin section through a keffir grain, after a preceding
+treatment with saffranin. The matrix is composed entirely of long thin
+bacilli (_Bacillus caucasicus_), while the peripheral portions, which
+are more deeply stained, consist to a large extent of dense masses of
+yeast cells with occasional streptococci. In a normal grain the latter
+organisms are present on the surface or in the cavities and grooves of
+the grain, and only to a less extent in the matrix. Nikolaiewa[57]
+claimed to have isolated a hitherto unknown bacillus capable of
+coagulating milk by acid production, _Bacterium caucasicum_, not
+identical with, but related to Freudenreich's _Bacillus caucasicus_, and
+also a torula. Although no experiments were carried out, Nikolaiewa
+asserts that this organism forms the matrix of the grains. He was able
+to produce a beverage resembling keffir, just as Freudenreich and
+Essaulow did with entirely different organisms, but his product would
+appear to have been slightly too acid and to have lacked the
+characteristic aroma of the normal product. In the course of an
+extensive series of experiments Kuntze[58] found the following
+organisms:
+
+  (_a_) True lactic acid forming bacteria, _Streptococcus
+  acidi lactici_ (Grotenfeldt).
+
+  (_b_) Bacteria of the group _Bacterium acidi lactici_
+  (Hueppe) and _Bacterium lactis aërogenes_.
+
+  (_c_) Various torula and yeast species.
+
+  (_d_) Two species of butyric acid bacteria, _Bacillus
+  esterificans_ and _Bacillus keffir_ (Kuntze).
+
+His conclusions are: 1. In any case the presence of a yeast capable of
+directly fermenting milk sugar is not essential. 2. The significance of
+the presence of yeast lies in the fact that stimulation of the lactic
+bacteria occurs; further, the yeast exerts a regulating influence upon
+the rapidity of the fermentation proper. The variety is of minor
+importance, provided always that the yeast does not produce an
+unpleasant flavour. By the use of mixed cultures of _Bacillus
+esterificans_, _Bacillus keffir_, and _Streptococcus acidi lactici_, and
+a keffir yeast, Kuntze obtained a product that possessed to the fullest
+degree all the characteristic properties of a normal keffir. In such
+cultures he was successful in obtaining the formation of keffir-like
+grains. Keffir fermentation is, according to Kuntze, the result of the
+action of various organisms. During the initial stage butyric acid
+fermentation takes place, but is prevented from becoming predominant by
+the action of the keffir yeast. Simultaneously a true lactic acid
+fermentation proceeds and eventually gives place to a subsequent
+secondary production of butyric acid. Finally, then, we have a certain
+amount of unison in the results obtained by Freudenreich, Essaulow,
+Nikolaiewa, and Kuntze. These show that, for the production of a
+characteristic keffir, specific organisms are not essential, provided
+always that those used possess, either individually or collectively, the
+essential capacity of acidifying, coagulating, and fermenting the milk.
+For the growth of normal grains the presence of a matrix-forming
+organism, such as _Bacillus keffir_, is indispensable.
+
+  [Illustration: FIG. 12—_Streptococcus lacticus_
+  (Grotenfeldt) growing on lactose-agar, stained by Gram's
+  method. ( ✕ 900 diams.)]
+
+_Diseases of Keffir Grains._—According to the age and the previous
+treatment to which keffir grains have been subjected, the vitality of
+one or more of the organisms constituting the grain may have been
+impaired. The results of Freudenreich have shown that _Saccharomyces
+keffir_ and _Streptococcus a_ are unable to withstand desiccation for
+more than a few days, and this is sufficient to account for the frequent
+failures to obtain normal keffir from the grain. Further, grains succumb
+to a mucilaginous disease; the cavities become filled with a slimy
+fluid, and the grains are covered with mucilaginous matter. They lose
+their elasticity and become brittle or mealy, but large grains appear to
+be more subject to this fault than do the small ones. Such grains
+should be disinfected by immersion for a short time in two per cent.
+salicylic acid solution, followed by drying in the sun, whereby they are
+completely regenerated.
+
+Another disease consists in the predominance of certain butyric acid
+bacteria which impart an unpleasant rancid taste to the keffir
+(Podowyssozki). This is generally attributed to the use of rich milk, or
+too high a temperature during preparation.
+
+_Koumiss._—Another product of the combined action of lactic acid and
+alcohol-producing organisms is called koumiss, kumys, milk-wine, lac
+fermentation, or vinum lactis. In the steppes of Southern Russia and
+Asia, as we have seen,[59] it is prepared chiefly from mares' milk, but
+occasionally from that of camels and jennets. The name is said to be
+derived from that of a tribe mentioned by Xenophon and Pliny, viz., the
+Kumanen, by whom its preparation was practised. After the war with the
+Tartars in 1215 its use was adopted by the latter people, and eventually
+spread to the Turkomanen, Kalmucks, Khirgiz, Mongolians, etc.
+
+Rubruck, in 1253, records the use of a fermented drink—kosmos—prepared
+from mares' milk, and about the same time Marco Polo mentions the
+occurrence of a milk-wine, chumis or chemius, among the Tartars. The
+fact that the Tartars were seldom ill, and were almost invariably free
+from lung troubles, led to an influx of visitors from surrounding
+countries, until finally its use spread to Russia, Austria, and Germany.
+At the present time the best koumiss is that produced in the province of
+Orenburg; but specially equipped koumiss establishments, under the
+control of physicians, exist in Odessa, Samara, Ufa in the Urals, and
+other districts. The curative properties of koumiss have long been
+recognised and its use is indicated in cases of indigestion, chlorosis,
+scurvy, tuberculosis, etc.
+
+Rubinsky states that, among the nomadic tribe, of Khirgiz and Kalmucks,
+a special leathern bottle (Turssuk, Orroth, or Soaba) is used for the
+preparation of koumiss, while wooden tubs (Tschiljak) similar in shape
+to the old-fashioned churn are used by the Bashkirs, and in koumiss
+establishments.
+
+The fermentation is induced by the addition of koumiss to fresh mares'
+milk, in proportions which vary according to the cleanliness observed in
+the actual preparation. Where the process is carefully controlled, one
+part of koumiss to ten parts of milk is often used, but where gross
+infection from outside sources takes place one part of koumiss to three
+parts of milk is taken. The mixture is stirred at frequent intervals,
+and stored at a temperature of 73°-90° F. Weak koumiss is obtained after
+twenty to twenty-four hours in winter and twelve to fourteen hours in
+summer, but is scarcely ever consumed immediately, as it possesses a
+strong purgative action.
+
+It is generally poured into bottles (bottled koumiss); or allowed to
+remain in the tubs (tschiljak koumiss); in the former case the
+fermentation is anaërobic, in the second it is aërobic.
+
+Storage of the koumiss upon ice or in a cellar is necessary since medium
+koumiss is converted to strong koumiss in twelve to sixteen hours at
+ordinary temperatures, while at the lower temperature this occurs only
+in two to four days.[60]
+
+According to Biel,[61] either old koumiss or the dried sediment from old
+koumiss may be used for the initial inoculation. It may also be prepared
+by the repeated inoculation of mares' milk with soured cows' milk until
+a fermenting product is obtained. Koumiss may be prepared by a method
+stated by Allik[62] to be in general use in the Caucasian
+health-resorts. One part of beer-yeast is added to four to ten parts of
+fresh mares' milk (according to the strength of product required), and
+after thorough mixture of the two liquids the whole is allowed to
+ferment at a temperature of 70° to 72° F. for two days. One part of this
+first product is then added to five parts of fresh cold milk, and
+allowed to stand three to four hours at 75° to 77° F. It is then poured
+into bottles, and after the expiration of another three to four hours is
+stored away in a cellar at about 45° F. This koumiss may be used at any
+time from one to five days (generally two to three) after bottling
+according to the strength desired or prescribed in each individual case.
+
+The changes undergone during fermentation consist in a vigorous gas and
+acid production accompanied by alcohol formation and coagulation of the
+milk. The coagulum exists in an extremely fine state of division, and
+the liquid froths violently on the bottle being opened. It has a full
+pleasant acid taste, but should not contain more than one per cent. acid
+and two per cent. alcohol. The specific gravity of koumiss is 1.008 to
+1.020 at 60° F. Appended is an analysis of two different samples of
+koumiss:
+
+  ──────────────────────┬────────────────────────────
+                        │       Prepared from
+  ──────────────────────┼──────────────┬────────────
+                        │ Mares' Milk. │  Separated
+                        │              │ Cows' Milk.
+  ──────────────────────┼──────────────┼────────────
+                        │  Per Cent.   │  Per Cent.
+  Water                 │   91.535     │   88.933
+  Fat                   │    1.274     │    0.854
+  Nitrogenous bodies    │    1.913     │    2.025
+  Sugar                 │    1.253     │    3.108
+  Ash                   │    0.293     │    0.444
+  Carbon dioxide        │    0.876     │    1.027
+  Alcohol               │    1.850     │    2.647
+  Lactic acid           │    1.006     │    0.796
+  Glycerine             │    ....      │    0.166
+  ──────────────────────┴──────────────┴────────────
+
+Fleischmann[63] gives a formula for preparing an artificial koumiss from
+separated cows' milk, water, cane sugar, and milk sugar, with the
+addition of distillery yeast. Needless to say, this product must possess
+some of the characteristic by-flavour of the yeast employed, and is less
+suitable than koumiss prepared by the aid of a lactic yeast. Schipin
+investigated the fermentation of koumiss and found three distinct
+organisms.
+
+Rubinsky in a recent article threw much light on the phenomena of
+koumiss fermentation. According to him, koumiss contains almost
+invariably four different organisms, viz., koumiss yeast, koumiss
+bacterium (_Lactobacillus_), _Streptococcus lactis_ (Lister), _Bacterium
+aërogenes_, and occasionally _Bact. caucasicum_ (Nikolajewa). For the
+preparation of normal koumiss only the two former organisms are
+required; they exceed in number any of the other organisms whose
+presence in the dairy is unavoidable. The presence of the two latter
+organisms is favourable to the production of good koumiss, as, by
+inducing a preliminary lactic fermentation, they tend to inhibit the
+growth of undesirable extraneous bacteria, etc. In medium and strong
+koumiss they die out on account of the amount of lactic acid formed
+(1%).
+
+Koumiss yeast possesses strongly differentiated protoplasm, but lacks
+any cultural characteristics. Abundant growth occurs in milk, and lactic
+acid (0.3%), alcohol, carbon dioxide, albumens and peptones, volatile
+acids, and aromatic substances are formed.
+
+Koumiss bacterium is related to the _Lactobacillus_ of various other
+fermented milks, and is similar to _Bac. acidophilus_, and possesses
+like these a distinct polymorphism (branched cells, long and short
+bacilli, etc.). It is non-sporogenous, has an optimum temperature of 90°
+to 97° F., and possesses cultural characteristics similar to those of
+the rest of the _Lactobacilli_.
+
+The by-products of koumiss yeast appear to favour the growth of the
+koumiss bacterium, as this organism, like the other _Lactobacilli_, is
+favourably influenced by the presence of small quantities of peptone,
+alcohol, and acid.
+
+The organisms found by Schipin consisted of a species of _Saccharomyces_
+and two bacilli, _Bacillus acidi lactici_ and a non-sporulating
+bacillus. The latter organisms coagulate milk at 98° F., but not at room
+temperature, and although a minute description of cultural
+characteristics is not given it would seem to be related to _Bacillus_
+or _Lactobacillus caucasicus_.
+
+_Leben Raïb_ or _Leben_ (_Laban._)—This is a beverage prepared largely
+by the Egyptians, and differs from keffir, as does matzoon, in
+possessing a characteristic aroma and taste. It differs also from the
+former by having only a very weak alcoholic fermentation, and by the
+coagulum being coarse and lumpy instead of being extremely fine. It is
+made from buffaloes', goats', or cows' milk by the addition of roba (or
+old leben) to the previously boiled and cooled fresh milk. The use of
+leben is many centuries old, and it is used in Egypt as in Arabia for
+medicinal purposes, although that of the Syrians and Arabians is said to
+differ from that of the Egyptians and Algerians. The fermentative
+changes occurring in the formation of the Egyptian leben have been
+investigated by Rist and Khoury,[64] and also by Guerbet,[65] who found
+that five organisms were normally present. These comprised a
+chain-forming bacillus (_Streptobacillus_), a second smaller bacillus
+(_Bacillus lebenis_), a diplococcus, a saccharomyces, and a mycoderma.
+Of these five organisms, it would appear that four live in metabiosis,
+the streptobacilli and bacilli hydrolyse the milk sugar, the components
+of which are split up by the yeast to alcohol and carbon-dioxide. The
+alcohol thus formed, together with the glucose formed by hydrolysis, are
+eventually converted to acid or combusted by the mycoderma species. The
+leben thereby assumes the sharp, unpleasant flavour met with in old
+samples. The diplococcus merely produces acidification and coagulation
+of the milk. Rist and Khoury were able, by the use of these organisms,
+to produce normal leben, especially when the true yeast was allowed to
+grow in the milk for some time before inoculation with the other
+organisms was made.
+
+Some of the half-civilised tribes of Siberia, the Tartars and the
+Burgaten, prepare a strong alcoholic beverage, arakà or ojràn, from
+fermented milk. This is really a product of distillation, and contains
+seven to eight per cent. of alcohol and volatile fatty acids.
+
+  [Illustration: FIG. 13—Photo-micrograph of preparation
+  from Armenian soured milk (Matzoon). This is related to
+  Yoghourt, and contains, as will be seen from the above
+  photo, yeasts, streptococci, diplococci, and a bacillus
+  with the morphology of _Bacillus bulgaricus._ This, and
+  similar foods, owe their peculiar properties primarily to
+  the presence of _Bacillus bulgaricus_ (type A, White and
+  Avery), and only in a lesser degree to the yeasts and
+  lactic streptococci.]
+
+_Matzoon._—This is a drink used largely in Western Asia, and is similar
+in character to keffir, but has a peculiar taste which distinguishes it
+from all other fermented milks. According to Weigmann,[66] it is
+prepared from buffaloes', goats', or cows' milk, and is used partly as a
+means of souring milk for butter-making and also as a lactic food, eaten
+with spoons. In the same way buttermilk produced from milk which has
+been previously ripened by matzoon is used as a beverage. Finally, the
+coagulum (_than_) of such buttermilk is strained off, and, after being
+pressed, is mixed with meal and dried by exposure to the sun's rays. The
+preparation of matzoon is in many respects very similar to that of
+keffir and koumiss, but differs by inducing a comparatively weak alcohol
+fermentation. In common, too, with yoghourt, the prevailing temperature
+is much higher than is required for keffir and koumiss.
+
+In regard to the biology of matzoon, the occurrence of various organisms
+has been recorded. Emmerling[67] isolated, in addition to a yellow
+pigment-forming organism, _Bacillus subtilis_, _Bacillus lactis acidi_,
+and several fungi, a small micrococcus capable of hydrolysing milk- and
+cane-sugar. The organism produces and without gas formation, or
+peptonisation of the medium. Of the nine yeasts isolated from matzoon by
+Lindner[68] and Kalantharianz,[69] three were able to ferment milk sugar
+without previous hydrolysis, while two others, by the simultaneous
+production of lactic acid and fruit esters, gave to the matzoon its
+characteristic taste and aroma.
+
+_Yoghourt and Soured Milk._—Yoghourt is another fermented milk, and is
+related to the matzoon of Armenia, the gioddu of Sardinia, and the leben
+of Egypt. After a preceding boiling and reduction of the volume of the
+milk, inoculation of the mass is made by the addition of a small
+quantity of old culture, and it is then allowed to sour at a
+comparatively high temperature. A moderately compact, jelly-like
+coagulum is thus formed, while keffir and koumiss possess a liquid
+consistency. The fermentation necessary for the two latter products only
+proceeds, too, at a much lower temperature, at which yeasts play an
+important part. According to Guerbet, yoghourt incubated for ten hours
+at 113° F. contained 0.34 per cent. lactic acid and 0.012 per cent.
+alcohol. Luerssen and Kühn[70] came to the conclusion that yoghourt
+contained chiefly a mixture of _Bacillus bulgaricus_, diplostreptococci,
+and a "granule" bacillus, so called on account of its granulated
+appearance after treatment with methylene blue. According to these
+authors, the first two organisms were found in each of eight samples of
+maya (young yoghourt) and of yoghourt itself, but the occurrence of the
+"granule" bacillus in plate cultures was by no means regular. In
+addition, yeasts were found in almost every sample examined, but were
+regarded more as accidental infections rather than as essential to the
+formation of a typical product. The combined action of the three
+organisms already mentioned gave rise to a product closely resembling
+normal yoghourt. Piorkowski[71] subjected Bulgarian maya to examination
+and associated himself with Metchnikoff[72] in finding three species, a
+streptococcus, a diplococcus, and a specific organism to which he gave
+the name _Yoghourt bacillus_. Similar results were also obtained by
+Grigoroff.[73] Piorkowski's _Yoghourt bacillus_ is similar in form to
+_Bacillus subtilis_, but does not sporulate, nor does it liquefy
+gelatine. Young individuals are stained by Gram's method; older
+individuals are, however, Gram negative. The optimum temperature is 112°
+F. Kuntze attempted to isolate the organisms mentioned by Luerssen and
+Kühn, and by plate culture procured growth of a spore-forming bacillus
+similar to Weigmann's _Bacillus matzoon_. To this organism is attributed
+the power to impart a specific taste to the matzoon, but as growth is
+comparatively slow, it can only be of significance in determining the
+quality of the curd and cheese prepared from this product. Cultures were
+also obtained which resembled in general character those of the organism
+described by Luerssen and Kühn as _Bacillus bulgaricus_ and named by
+Kuntze _Bacterium W_. Granule formation was transient in this culture,
+and the organisms eventually became inactive. Further analysis of maya
+gave cultures of the "granule" bacillus, but these passed over from the
+type forming irregular colonies (see Figs. 14, 15, 16) to that producing
+smooth colonies. Further, although the granule formation persists
+largely in milk, the organisms soon revert to the non-granular type if
+cultivated on agar. By the use of the Gram-Weigert stain organisms from
+a several-days-old culture on beer-wort-agar gave an interesting
+reaction. The bacillar threads are in places Gram-negative, in others
+Gram-positive, and bear small club-like swellings (see Fig. 14). Results
+similar to these were also obtained with cultures of _Bacillus matzoon_
+(Weigmann and Grübner) and also with _Bacillus acidophilus_.
+
+Neisser's method of staining failed to give such good effects by the
+examination of fresh maya, as did an alcoholic aqueous solution of
+methylene blue in showing up the granules of the organisms. Again,
+Grixoni[74] found, but did not isolate, a similar granule-forming
+organism (_Bacterium sardous_) in Sardinian gioddu. As already
+mentioned in the description of leben, Rist and Khoury found a long
+bacillar lactic ferment (_Streptobacillus lebenis_) which also exhibited
+the irregular greyish white hairy colonies and high optimum temperature
+characteristic of this group. On account of the similarity in form,
+staining reactions, temperature requirements, and cultural growth of the
+organisms described by Emmerling, Düggeli, Weigmann, Grixoni, and Rist
+and Khoury, Kuntze is inclined to regard them as belonging to one single
+group of lactic ferments. According to him the granule formation is
+rather variable, and may be induced or suppressed by cultural methods.
+Not only do organisms of this group produce far more acid than the
+normal lactic bacteria; they are also more resistant to acid, and are
+able to develop in milk to which 0.5 per cent. hydrochloric acid has
+been added. A comparatively high percentage of alcohol seems to
+encourage growth, and this was obtained in milk containing 4 per cent.
+alcohol. This would no doubt tend to explain the phenomenon observed by
+Kuntze that milk is not so rapidly fermented by organisms of this group
+as when cultures of diplococci and yeasts are added. Since organisms of
+this group would seem to be widely distributed, the question of their
+natural habitat arises. Luerssen and Kühn were unsuccessful in their
+search for such organisms in Königsberg milk, but Leichmann records the
+occurrence of a long bacillus (_Bacillus lactis acidi_) in milk that had
+spontaneously soured at 112° to 120° F. This organism, too, showed
+characteristic growth on agar media, and produces lævo-rotatory lactic
+acid. The examination of calves' stomachs showed, according to Kuntze,
+only occasional long bacilli, but inoculation of sterile milk and
+incubation at 100° F. with repeated over-inoculation gave a culture
+showing the characteristic granule reaction (see Figs. 18 and 20).
+Although plate cultures made direct from calves' stomachs do not exhibit
+the regular contours generally shown by the granule bacillus, yet this
+growth may be induced by preceding cultivation in lactose bouillon to
+which 0.5 per cent. acetic acid has been added. A similar organism,
+_Bacillus acidophilus_, was isolated from calves' manure by means of
+this acetic bouillon, as was also a diplostreptococcus which resembled
+very closely the typical lactic acid streptococcus. This resemblance was
+made all the more striking by the fact that they were capable of
+coagulating milk at a temperature of 99° to 104° F. Since these
+organisms are present in large numbers in manure and also in the
+digestive tract of ruminants, it would seem probable that their
+occurrence is not without significance for the operations of cheese
+manufacture. According to Jensen, the practice of applying farmyard
+manure to Swiss meadows has been regarded as absolutely essential to the
+production of cheese of the best quality; while, on the other hand, the
+application of artificial manures would seem to have been responsible
+for an increase in abnormal cheese. Kuntze found further that by the
+combined inoculation of sterile milk with the diplostreptococcus and the
+"granule" bacillus from calves' stomachs, together with a yoghourt
+yeast, he was able to obtain a product possessing a taste and aroma
+little different from normal yoghourt. During their investigations upon
+the ripening of Swiss hard cheese, Freudenreich and Jensen[75] isolated
+five varieties of lactic acid bacilli, and were able to show that one of
+these, especially _Bacillus casei ε_, was of the greatest
+importance for the production of good cheese. This organism has been
+found by Thöni to be present in rennet tablets, while a related
+variety, _Bacillus casei δ_, was found in fresh calves'
+stomachs. Unfortunately, staining tests with these organisms were not
+carried out, so that no data are available in regard to the presence of
+granules. The photo-micrographs of these organisms show the small clubs
+and true-branched forms. The presence of these diplococci and bacillar
+lactic ferments in the intestinal tract of ruminants and horses might
+possess some importance for the preparation of yoghourt in bags or tubes
+made from the stomachs of these animals. Finally, Moro[76] has isolated
+an acidophilic organism from the dejecta of infants which resembles
+closely, both in manner of growth, resistance to acids, true branching,
+and temperature optimum, the granule bacillus and related forms.
+
+[This group of sixteen illustrations (Figs. 14 to 29), showing various
+aspects of the Yoghourt bacillus and others of a cognate nature, is
+taken from the _Centralblatt für Bakteriologie_ of Jena.—L. M. D.]
+
+  [Illustration: FIG. 14.—Granule Bacillus from Yoghourt.
+  Shredded preparation of a fresh skim-milk culture at 37°
+  C. for six hours. Stain: aqueous methylene blue. (Enlarged
+  1:500.) In Figs. 15 and 17 will be noticed the chain
+  arrangement of the bacillus, which, in spite of the
+  supposed data of Luerssen and Kuhn, will be generally
+  noticed in the granule bacillus.]
+
+  [Illustration: FIG. 15.—Granule Bacillus from Yoghourt,
+  cultivated after the usual Agar method, for twenty-four
+  hours at 37° C. Stain: aqueous methylene blue. (Enlarged
+  1:500.)]
+
+  [Illustration: FIG. 16.—Granule Bacillus from Yoghourt.
+  Agar Milk Sugar Culture cultivated for forty-eight hours
+  at 37° C. Below is the true branching, above, the
+  distorted involution form. This production of involution
+  forms occurs chiefly in old cultures, and is an indication
+  of degeneration. Stain: aqueous methylene blue. (Enlarged
+  1:700.)]
+
+  [Illustration: FIG. 17.—_Bacteria W._ from Milk,
+  cultivated twenty-four hours at 37° C. Methylene blue.
+  (Enlarged 1:500.) The similarity in the pictures ought to
+  serve as a proof of the near relation of the granule form
+  and non-granule varieties.]
+
+  [Illustration: FIG. 18.—Agar Milk Sugar Culture. From the
+  original Bulgarian Yoghourt. In the centre, and beneath,
+  the characteristic hairy irregular colonies of the granule
+  bacillus (_Bacillus bulgaricus_ group), to the left, the
+  smooth contoured yeast colonies. The colonies of the
+  former organism always remain microscopic in size.
+  (Incubated several days at 20° to 25° C. Magnified X 10.)]
+
+  [Illustration: FIG. 19.—Agar Milk Sugar Culture. Surface
+  colony of granule bacillus from calf's stomach. The great
+  resemblance this colony bears to those formed by the
+  granule bacillus from Yoghourt will be apparent. This
+  fact, as well as close agreement in other cultured
+  features, induced Kuntze to place these organisms in one
+  group. (Incubated two days at 37° C. Magnified X 100.)]
+
+  [Illustration: FIG. 20.—Agar Milk Sugar Culture.
+  Deep-lying colony of granule bacillus from calf's stomach.
+  The form of the colony is often determined by the relative
+  presence or absence of air. (Two days at 37° C. Enlarged
+  about 1:50.)]
+
+  [Illustration: FIG. 21.—Agar Milk Sugar. Colony of
+  _Bacterium W._ from Yoghourt (non-granular variety of the
+  granule bacteria, as far as possible identical with
+  Luersen and Kühn's _Bacillus bulgaricus_), of a cubical
+  branching-out form.
+
+  According to Kuntze, the granule formation of this and
+  related organisms is variable, while White and Avery
+  regard it as a constant characteristic. (Incubated two
+  days at 37° C. Magnified x 50.)]
+
+  [Illustration: FIG. 22.—Two colonies of _Bacillus
+  acidophilus_ from calf's manure. Agar Milk Sugar Culture.
+  With this organism, also, we have conformation to one type
+  of colony, while, in other respects, temperature
+  requirements and production, etc., we have close agreement
+  with the granule bacillus (_Bacillus bulgaricus_). (Two
+  days at 37° C. Enlarged about 1:50.)]
+
+  [Illustration: FIG. 23.—Beer-wort Gelatine.
+  Fourteen-days-old colony of Yoghourt yeast. (Enlarged
+  about 1:50.)]
+
+  [Illustration: FIG. 24.—Shredded preparation of the
+  Bulgarian original Yoghourt. Stain: aqueous methylene
+  blue. Granule bacillus, diplostreptococci, and yeast. (See
+  also other photo-micrographs of Yoghourt. Enlarged
+  1:70.)]
+
+  [Illustration: FIG. 25.—Granule Bacillus from Yoghourt.
+  Cultivated in skim milk in twenty-four hours at 37° C.
+  Stain: aqueous methylene blue. (Enlarged 1:50.)
+
+  By means of this staining treatment the presence of
+  granules (not spores) can be easily detected. Treatment
+  with fuchsine fails to bring out these formations.]
+
+  [Illustration: FIG. 26.—_Bacteria W._, Agar Milk Sugar
+  Culture. Cultivated twenty-four hours (knobs, clubs).
+  Stain: Gram's method coloured with aqueous fuchsine
+  afterwards. (Enlarged 1:600.)]
+
+  [Illustration: FIG. 27.—_Bacteria acidophilus_ from
+  calves' manure, isolated by means of bouillon as acid as
+  vinegar. Shredded out of the usual Agar culture.
+  Twenty-four hours at 37° C. Stain: aqueous methylene blue.
+  (Enlarged 1:700.)]
+
+  [Illustration: FIG. 28.—Mucus from calf's stomach
+  inoculated into milk after eight transferrings. Shredded
+  preparation cultivated in milk for twenty-four hours at
+  37° C. Diplostreptococci and granule bacillus. Stain:
+  aqueous methylene blue. (Enlarged 1:500.)]
+
+  [Illustration: FIG. 29.—Diplostreptococcus from Yoghourt.
+  Pure culture in skim milk. A comparison of the
+  illustrations will show how close a resemblance exists
+  between bacteria found in the mucous membrane of calf's
+  stomach and those occurring in Yoghourt. In fact, by the
+  combined action of granule bacilli, and of
+  diplostreptococci from calf's stomach, together with a
+  Yoghourt yeast, it is possible to prepare normal
+  Yoghourt.]
+
+In a review of the literature of the subject of soured milks, Makrinoff
+suggests the adoption of the two names, _Streptobac. lebenis viscosus_
+and _Streptobac. lebenis non-viscosus_, for the organisms of the
+so-called Bulgaricus group, and known at present as
+_Bacillus-bulgaricus_, _Streptobac. lebenis_, _Bacillus of Massol_,
+_Granule bacillus_, _Bact. Mazun_, _Bac. lactis acidi_, etc.[77]
+
+White and Avery[78] have made a comparative study of a large number of
+varieties and species of lactic acid bacteria of the above type obtained
+from various fermented milks and milk tabloids. Their descriptions are
+so detailed and their conclusions are so important that we give them at
+length. According to this work, the whole of the thermophilic lactic
+acid bacilli of the so-called Bulgaricus type may be divided into two
+sub-types, A and B.
+
+
+_The Cultural Characteristics of the Bacillus Bulgaricus Group_
+
+The cultural characteristics of all the strains of _Bacillus bulgaricus_
+(granule bacillus) are as follows:
+
+_In Whey Agar._—All strains exhibit wide variation in size, 2 µ to 50 µ
+long and about 1 µ broad.
+
+Almost all individuals are intensely Gram-positive, and show regularity
+of outline. All strains show involution form, exhibiting vacuoles, and
+often show empty cell membranes. The latter are Gram-negative, and vary
+greatly in both dimensions as well as in form. All strains show tendency
+to chain formation, some being arranged in chains of six to twenty-five
+segments, which may contain both Gram-positive and Gram-negative
+individuals. Type B exhibits Gram-negative spherical bodies varying from
+0.25 µ to 1 µ in size, adhering to the sides of some of the
+Gram-negative individuals.
+
+_In Whey._—In this medium there is a marked tendency toward
+degeneration and involution. In the early stages of incubation, at 100°
+to 112° F., the bacilli are uniform in size and intensely Gram-positive;
+in succeeding stages the irregular, vacuolated, inflated, and ruptured
+forms predominate. Between the eighteenth and twenty-fourth hours of
+incubation at 112° F. the strains of type A develop oval to
+kidney-shaped nodules attached to a stem extending from the cell
+substance. As the incubation is prolonged these nodules increase in
+size, often measuring 1 µ to 2 µ in length; this nodule formation occurs
+at the expense of the cell protoplasm, and appears to be a marked
+characteristic of growth in whey. Cultures of type B do not form nodules
+or clubs, but small spherical bodies more or less securely attached to
+the cell wall are seen. Again, type A assumes the form of small bacilli
+in chains, while type B strains develop to a greater length and exist
+almost exclusively as single isolated forms. True branching has been
+observed in strains of type B.
+
+_In Milk._—In milk there is a tendency to thread-formation consisting
+of four to ten segments in the case of type A, while type B shows longer
+and more curved forms. With increasing age of the culture there also
+appears to be increase in the length of the organisms. All strains are
+non-motile, non-sporogenous, and non-capsule-forming.
+
+_Staining Reactions._—All strains are readily stained by the usual
+aniline dyes.
+
+_A. Gram's Method._—Young individuals give an intense reaction with
+this stain; old bacilli are easily decolourised, and degenerate forms
+are always Gram-negative, while single individuals have been observed
+which showed gradation from one pole of the cell to the other.
+
+_B. Loeffler's Methylene Blue._—According to the behaviour of the
+organisms studied, a separation into two types appears possible, type A
+being uniformly impregnated, while type B shows distinct
+differentiation. The cell body is seen to contain a varying number of
+round to oval bodies or granules. This is the appearance already
+mentioned by Düggeli, Luerssen and Kühn, and Kuntze, and from which the
+granule bacillus derives its name. In opposition to the observations of
+Kuntze, the occurrence of granules was not found to be variable; it was,
+indeed, so constant as to constitute a distinguishing characteristic
+between the two types. The organisms of this group are difficult to
+cultivate, and freshly isolated growth is obtainable only on media
+containing whey, malt, or in milk. They grow equally well under aërobic
+or anaërobic conditions. The optimum temperature for growth is 113° to
+115° F.; growth is fair at 85° F., slight at 75° F., and does not take
+place at 68° F.
+
+Colonies on whey agar are round to irregular, greyish white, curled and
+filamentous, often streaming, and in a few cases smooth and even in
+structure. Gelatine is not liquefied. There is no surface growth on
+gelatine stab-cultures. Along the stab the growth is filiform, beaded,
+with subsequent horizontally projecting ramifications. Milk is
+coagulated in eight to eighteen hours at 112° F., and is the most
+favourable medium for growth.
+
+[I am indebted for this group of illustrations (seventeen in number) to
+the editor of _Bacteriotherapy,_ New York, U.S.A.—L.M.D.]
+
+  [Illustration: FIG. 30—Photo micrograph of preparation
+  made from Yoghourt, showing yeast cells, large lactic
+  diplococci, small slender bacilli and many large bacilli
+  possessing the morphology of _Bacillus bulgaricus_. Yeast
+  cells are almost invariably found in native Yoghourt, but
+  do not appear to be essential to the production of a
+  tropical beverage. Indeed, they would seem to be
+  responsible for the unpleasant astringent taste often met
+  with in old samples of this product.]
+
+  [Illustration: FIG. 31—Photo micrograph of smear from
+  Greek Curdled Milk called "Giaourti," and showing yeast
+  cells, long bacilli and a mould (_Oidium lactis_),
+  possessing very large elongate cells. The presence of the
+  latter is very undesirable, as it rapidly combusts the
+  lactic acid, digests the casein, and imparts a strong
+  unpleasant cheesy flavour to the beverage.]
+
+Type A produces 2.7 per cent. to 3.7 per cent. inactive lactic acid in
+milk, while type B produces only 1.2 per cent. to 1.6 per cent.
+lævo-rotatory lactic acid in milk. There is a small quantity of acetic,
+formic, and succinic acids formed. The conclusions of White and Avery
+are:
+
+I. A review of the morphological culture and biochemical features of the
+lactic acid producing bacilli from yoghourt, matzoon, and leben, appears
+to justify their classification as a single group.
+
+II. This group would seem to be identical with _Bacterium caucasicum_
+(Kern).
+
+III. The significant variations exhibited by these bacilli in regard to
+the presence or absence of granules demonstrable by differential stains,
+the degree of lactic acid production, and the nature of the acid
+produced, suggest a division into two different types—the true type A,
+and the paratype B.
+
+Quite recently Hastings and Hammer[79] recorded the isolation from milk
+of an organism producing more acid than either _Bacterium coli commune_
+or _Bacillus lactis acidi_. It is characterised by possessing a high
+optimum temperature, and by the limited conditions under which it grows
+on nutrient media. On this account these investigators suppose it to be
+related to those described in the paragraphs on fermented milks, leben,
+matzoon, etc., and which are regarded by Kuntze as being identical.
+
+Similarly Boutroux[80] found 1.5 per cent. acidity produced in a
+solution containing albuminous matter and glucose; while Richet[81]
+states that with the addition of gastric juice to milk as much as four
+per cent. acidity may be formed. After storing samples of milk for eight
+days at 100° F., Koning[82] found 2.35 per cent. and 2.5 acid; while
+similar samples stored at 60° to 62° F. for the same period only
+developed 0.9 per cent. Heinemann[83] records the production of 3.0 per
+cent. acid in milk incubated at 100° F.; and Jensen states that
+_Bacillus casei ε_ is capable of developing 2.7 per cent.
+lactic acid.
+
+Dr. H. B. Hutchinson, bacteriologist at Rothamsted Experimental Station,
+has also been successful in isolating a bacillus from English market
+milk resembling in every particular those classified by White and Avery
+as type A.
+
+  [Illustration: FIG. 32 is a photo-micrograph of soured
+  milk inoculated with a tablet containing viable and pure
+  cultures of _Bacillus bulgaricus_, and incubated for
+  seventy-two hours. These tablets constitute a valuable
+  means of preparing soured milk for therapeutic purposes.]
+
+  [Illustration: FIG. 33 is a photo-micrograph of milk
+  inoculated with a ferment tablet in which _Bacillus
+  bulgaricus_ is no longer viable, and the only growth
+  obtained is that of an organism allied to the _Bacillus
+  subtilis_ (Hay bacillus) group. Such milk would be
+  absolutely without value.]
+
+It will thus be seen that organisms related to those of Oriental and
+Occidental milk beverages are present in conditions where it is
+impossible for them to attain to any active growth. The same class of
+organism has also been found in many cases in butter and cheese
+throughout the United States.
+
+Of recent years the consumption of milk fermented by these organisms has
+been introduced more or less successfully into all European countries.
+This custom is due, as we have seen,[84] to a very great extent to the
+announcement of Metchnikoff[85] that the action of such organisms in the
+alimentary tract conduce to a prolongation of life. Moro found that the
+dejecta of children contain large numbers of _Bac. lacidophilus_ and
+_Bac. bifidus_, but, as age advances, the bacterial flora of the
+intestines tends to change. The number of acid-producing organisms
+gradually becomes less, and other bacteria capable of producing
+far-reaching decomposition of albuminoid matter tend to increase.
+
+Working on the assumption that senility is partially due to the
+absorption of by-products formed from albuminoid food by the
+decomposing or putrefactive bacteria mentioned, Metchnikoff instituted a
+search for organisms capable of suppressing the growth of the
+putrefactive bacteria.
+
+It has long been known that milk allowed to become sour will keep for a
+considerably longer period in hot weather than if lactic bacteria had
+not grown. This preservative action of lactic acid also comes into play
+in the manufacture of sauerkraut and in the preservation of meat by
+immersion in sour milk.
+
+  [Illustration: FIG. 34.—Photo-micrograph of smear of
+  culture of _Bacillus bulgaricus_, recommended by
+  Metchnikoff for use in cases of intestinal
+  auto-intoxication. Unlike the ferments of normally soured
+  milk, which are sometimes indifferent, or even injurious,
+  in their action, this bacillus is capable of growth at
+  blood heat, and, by producing much larger quantities of
+  lactic acid than such organisms as _Streptococcus
+  lacticus_, _Bacillus coli commune_, or _Bacteria lacticus
+  aërogenes_, inhibits the multiplication of bacteria
+  responsible for the putrefaction of albuminoid food in the
+  intestines.]
+
+Bienstock has shown that the growth of _Bac. putrificus_ is inhibited by
+the action of _Bact. coli commune_, which is capable of setting up a
+slight lactic acid fermentation. _Bact. coli commune_, however, gives
+rise to substances of an injurious character, and, although present very
+abundantly in the intestinal tract, it may by reduced almost entirely by
+the active growth of lactic acid bacteria. This fact is of great value
+to the cheese-maker, since by the addition of a lactic acid culture
+(starter) to milk before renneting, gas-producing bacteria such as
+_Bact. coli_ may be checked in growth. Since the ordinary lactic acid
+bacteria such as _Streptococcus lacticus_, _Bac. lactis acidi_, and
+others, are incapable of growth at blood temperature, it appeared
+necessary to procure cultures of lactic bacteria able to grow at
+temperatures of 100° F. to 112° F. Such an organism was found in
+Bulgarian soured milk (yoghourt), and was considered pre-eminently
+adapted to this purpose. As has been shown in the preceding paragraphs,
+this organism is merely one of a large group of bacteria found
+distributed in the intestinal canal of many domestic animals, in manure,
+and in ordinary market milk. It is then not surprising that the
+introduction into the intestinal tract of bacteria of the type
+_Bulgaricus_ in the form of tabloids has not met with any decided
+success. Although it was considered to be merely necessary to introduce
+the desired type of organism into the body, and the amount of lactic
+acid taken into the system by the administration of soured milks was
+looked upon as of secondary importance, yet, it would seem, in the light
+of recent investigations, that benefits derived from a soured milk
+regimen are attributable in part to a chemical as well as a purely
+bacterial action. This receives support from the fact that soured milk
+beverages prepared by the use of ordinary lactic bacteria, distinct from
+those of the _Bulgaricus_ type, often exert a beneficial influence upon
+human beings even although the organisms responsible for the
+fermentation are incapable of growth at blood temperature.
+
+It may be mentioned in conclusion that cultures prepared by the use of
+organisms of the type _Streptococcus lacticus_ combined with _Bac.
+bulgaricus_ possess a more agreeable flavour and aroma than those
+prepared from a pure culture of _Bulgaricus_ alone.
+
+  [Illustration: FIG. 35—_Bacillus bulgaricus_, showing the
+  cultures in English cow's milk. (Magnified 450 diams.)]
+
+  [Illustration: FIG. 36—Photo-micrograph of pure culture
+  of _Bacillus bulgaricus_. The administration of cultures
+  of this organism is indicated in all cases of intestinal
+  ailments, caused by the excessive growth of proteolytic
+  bacteria, and consequent putrefaction of foods in the
+  alimentary tract. By the formation of large quantities of
+  lactic acid, a state of asepsis is ensured, which is
+  particularly valuable in cases of operations on the
+  abdomen and intestines.]
+
+  [Illustration: FIG. 37.—Photo-micrograph of smear of
+  combined culture of _Bacillus bulgaricus_ and _Bacteria
+  paralacticus_. This double culture possesses an advantage
+  over single cultures in that, while the characteristic
+  disinfecting action of the former is retained, any
+  secondary action of the growth of this organism upon the
+  milk-fat is checked by the growth of _Bacillus
+  paralacticus_, thus ensuring the production of a more
+  palatable product.]
+
+
+
+
+CHAPTER VI
+
+THE PREPARATION OF SOURED MILK IN THE HOUSE
+
+
+There is no great difficulty in making soured milk at home: the
+necessary operations are quite simple, but at the same time they must be
+conducted with precision and care, otherwise the results may be
+unsatisfactory and disagreeable; there may even sometimes be danger in
+badly prepared sour milk. It is always an advantage in such matters to
+understand the reason of things, and a few notes on the surrounding
+conditions, and what has to be accomplished, may be of assistance to the
+would-be experimenter.
+
+The majority of intelligent people are now acquainted with the fact that
+the germs of bacteria are to be found everywhere on the surface of the
+earth, in air, and in water, and that they are the sole cause of the
+decay of all manner of perishable articles.
+
+The distribution is unequal—bacteria are much more plentiful where
+there is decaying matter—in dirty houses, sewage, or other contaminated
+water, etc. Milk is a splendid food for bacteria, and numerous varieties
+multiply in it exceedingly, and many of these are injurious, producing
+putrefactive changes which render the milk unwholesome, even poisonous
+in some cases. Others are beneficial, and are absolutely necessary for
+the souring of milk for making butter or cheese and for the ripening of
+the latter. The soured milk which is the subject of this book is the
+work of certain lactic-acid-producing bacteria, and the problem we have
+before us is to encourage the growth of the latter to the uttermost and
+to exclude the others.
+
+As bacterial germs are present in the air and readily sow themselves
+into any medium with which they come in contact, the first consideration
+is to get good fresh milk which has been as little exposed to the air as
+possible. The second is to conduct the experiment where the germs are
+fewest, and in cleanly surroundings, far removed from decaying matter
+and free from taints and smells.
+
+  [Illustration: FIG. 38.—Photo-micrograph of smear of
+  one-month culture of _Bacillus bulgaricus_. In spite of
+  its age, the culture is perfectly free from any foreign
+  organisms, which would otherwise lower its value for the
+  preparation of soured milk, and might, indeed, make it
+  directly injurious.]
+
+  [Illustration: FIG. 39.—Photo-micrograph of culture of
+  _Bacillus bulgaricus_ in malt. In cases of acute
+  enteritis, where milk cannot be supported, the lactic
+  bacilli may be cultivated in malt, and administered to the
+  patient in this form, with occasional doses of syrup of
+  malt, in order to induce a vigorous growth of the lactic
+  ferments in the body.]
+
+  [Illustration: FIG. 40.—Photo-micrograph of smear from
+  milk that had been allowed to sour spontaneously. Ordinary
+  market milk is always subject to infection from the air,
+  milking vessels, manure, etc., and from these sources a
+  mixed bacterial flora arises, with the result that the
+  milk exhibits curdling, acidity, gaseous fermentation, or
+  mould growth, after being stored for a short time. This is
+  due to the action of sush bacilli, diplococci, yeasts, and
+  moulds as are shown in this illustration.]
+
+However fresh the milk may be, it will contain useless or injurious
+bacteria, and we must get rid of these before attempting to introduce
+those whose growth we wish to encourage. This is effected by heat. All
+the living bacteria and most of the germs are killed at temperatures
+somewhat under the boiling point. Having sterilised the milk in this
+way, it is necessary, as far as possible, to prevent the entrance of
+fresh germs from the atmosphere, and we therefore let the milk cool down
+in covered dishes. When the temperature descends to about 100° F. the
+culture of the special bacteria is introduced, the covers are replaced,
+and the milk vessels maintained at or near this temperature for twelve
+hours, when the soured milk is ready for use. It is not necessary to use
+fresh culture every time—a little of the soured milk will take its
+place, and this may be repeated as many as fourteen times before it is
+necessary to start off again with a fresh culture. A great deal depends
+on the care exercised and the freedom of the surroundings from bacterial
+germs. Under the best conditions wild germs will gradually accumulate in
+the soured milk, but their increase may be greatly delayed by attention
+to the precautions mentioned. The ordinary souring of milk for butter
+and cheese making is conducted in cool surroundings, as already stated,
+because in such conditions the lactic-acid-producing germs increase
+relatively faster than the wild germs, and so gain the upper hand, but
+in the case of our special soured milk we kill out, practically, all
+wild bacteria and germs, and the pure culture having the field to
+itself, we can conduct the operation at a higher temperature where the
+action of the bacteria is at its maximum, and so obtain the necessary
+lactification in the minimum of time.
+
+The appliances for the souring of milk on the domestic scale require
+some consideration. We propose to describe the principal forms of
+apparatus which have been put on the market for the purpose, and then to
+give such suggestions as may assist the ingenious in making apparatus
+for themselves. Those who wish for information on the subject of larger
+apparatus will find it in the following chapter.
+
+  [Illustration: FIG. 41—Photograph of Agar Culture,
+  inoculated with a lactic powder offered to consumers under
+  a fancy name. Working on the assumption that the presence
+  of lactic bacteria is inimical to the growth of septic
+  organisms, this preparation has been placed on the market.
+
+  The plate shows, however an abundance of colonies of
+  foreign organisms—sporogenous bacilli, _Staphylococcus
+  pyogenes albus_, and _Staphylococcus pyogenes aureus_.
+  These organisms are shown in the appended
+  photo-micrographs, and constitute impurities in the
+  preparation.]
+
+  [Illustration: Spore forming bacillus]
+
+  [Illustration: _Staphylococcus pyogenes albus_]
+
+  [Illustration: FIG. 42—Photograph of Test Tubes of Sterile
+  Milk, inoculated with a tablet preparation said to contain
+  pure cultures. The darker liquefied portion of the
+  tube-contents is due to digestion of the curd by
+  proteolytic bacteria, thus indicating impure culture. Pure
+  cultures of lactic acid bacteria coagulate the milk
+  uniformly, but do not produce any subsequent change in the
+  appearance of the culture, even after several months.]
+
+  [Illustration: FIG. 43—Photograph of Test Tubes of
+  Sterile Milk, each tube having been inoculated with a
+  tablet of a preparation said to contain pure cultures.
+  Here, again, there is evident peptonisation of the curd,
+  thus indicating infection by proteolytic ferments.
+  Cultures from these tubes demonstrated the presence of a
+  foreign organism. Microscopical examination failed to
+  disclose the presence of _Bacillus Bulgaricus_.]
+
+  [Illustration: FIG. 44—Photograph of Test Tubes of
+  Sterile Milk, inoculated with a tablet of
+  "Lactobacilline." In contra-distinction to those shown in
+  Figs. 42 and 43, these tubes exhibit homogeneous curdling
+  of the milk without any subsequent digestion or
+  peptonisation of the coagulum. This is indicative of the
+  purity of the culture.]
+
+The Society "Le Ferment" of Paris, which has been authorised by
+Professor Metchnikoff to prepare and supply to the public his sour milk
+culture, provides an apparatus for the treatment of the milk. It is
+shown in Fig. 45, which consists of a double box having the intervening
+space packed with a non-conducting material. It is provided with a
+tight lid. Inside, there is accommodation for two milk vessels, each
+with a capacity of about two thirds of a pint. The most difficult thing
+in the souring of milk is to maintain the temperature as nearly at 100°
+F. as possible while the culture is in action. This result is attained
+by filling the vessel in the middle with boiling water. The insulated
+walls hinder the escape of heat, and the quantity of boiling water used
+is calculated to maintain the temperature steady for the twelve hours of
+cultivation; but in cold, frosty weather it is necessary to refill the
+central vessel with boiling water in the middle of the period.
+
+  [Illustration: FIG. 45]
+
+The milk jars are washed with hot boiled water and turned upside down to
+dry. They should not be wiped with a cloth. Boil the milk to be treated
+for ten minutes, stirring it to promote evaporation, as it is
+advantageous to have it in concentrated form. Cool rapidly to 100° F. by
+placing the boiling vessel in cold water, add to each bowl one third of
+a tube of the culture in powder form, fill up with the boiled and cooled
+milk, stir well and cover. Place the jars in the box and fill the
+central vessel with boiling water, shut the lid tight, and do not open
+it (unless a fresh charge of boiling water is needed) for ten or twelve
+hours, when it will be ready for use. If the liquid culture is used (one
+small phial for each bowl) the milk should be cooled to 86° F. instead
+of 100° F., as with the powder. The culture is also supplied in tabloid
+form. The powder and tabloids keep well, but the liquid can only be
+relied on for about two months. The milk prepared as above should be
+stored in a cool place, the lids being kept on the bowls. It is good for
+about two days, after which it becomes too sour. It can be eaten with
+sugar, which not only sweetens it but is beneficial in affording
+additional suitable food for the acid-producing bacilli. If fresh milk
+cannot be had, condensed, sterilised, or pasteurised milk may be used,
+but, of course, fresh milk is best. Condensed milk should be diluted
+with two parts of boiling water and then treated like ordinary milk.
+
+An apparatus on similar principles is sold by the Maya Bulgare Company,
+Ltd., and is illustrated in Fig. 46.
+
+  [Illustration: FIG. 46—Soured Milk Apparatus of the Maya
+  Bulgare Company, Limited, consisting of an insulated box,
+  hot-water vessel, and covered vessels containing the milk
+  and culture. The apparatus consists of cabinet in deal,
+  Maya Bulgare ferment in 20-dose bottles, Maya Bulgare
+  ferment in 100-dose bottles, compressed Maya Bulgare
+  tablets in boxes of 8 tubes, Maya Bulgare caramels in
+  boxes of 40, reduced milk, china funnels, and
+  thermometers.]
+
+The box is insulated, but the door is on the side, the hot water vessel
+is underneath, and the covered vessels containing the milk and culture
+are placed on a shelf above. In the front of the illustration are shown
+the various packages in which the liquid and powder cultures are put up.
+The procedure is exactly the same as with "Le Ferment" apparatus.
+
+Lactic Ferments, Limited, make use of a different principle to maintain
+the temperature steady during the lactifying period. Their apparatus
+(Fig. 47) consists of a water vessel mounted on a stand. The milk
+vessels (tumblers) are placed in the water, and the temperature
+maintained at the proper figure by a small night light burning
+underneath. It is recommended that the milk should be placed in an
+earthenware jar or jug, which is stood in a pot of water kept boiling
+for an hour. After cooling add from three to six previously crushed
+tabloids of culture, and stir well with a glass rod which has been
+sterilised in boiling water. The milk is then transferred to three
+tumblers, which it should fill, and these are put into the water vessel,
+the water in which should be at about 100° F., and the night light
+started.
+
+  [Illustration: FIG. 47]
+
+Messrs. Allen & Hanbury, Limited, also make use of the night light to
+maintain the proper temperature during incubation in their "Sauerin"
+apparatus (Fig. 48).
+
+No water, however, is placed in the metal container. The procedure is
+the same as that already described, and both tablet and liquid pure
+cultures are supplied. For children it is recommended that the
+incubation should occupy from three to four hours only, in other cases
+eight to ten hours. Grated nutmeg, ground cinnamon, or other flavouring,
+and cream may be used with the soured milk.
+
+The night light is also employed in the "Veronelle" apparatus of Messrs.
+Clay, Paget and Company, Limited (Fig. 49).
+
+  [Illustration: FIG. 48.—Messrs. Allen & Hanbury's Soured
+  Milk Apparatus. They maintain the temperature by means of
+  a night light, and the culture they use they call
+  "Sauerin."]
+
+  [Illustration: FIG. 49.—Vironelle Apparatus for souring
+  milk, made by Messrs. Clay, Paget & Company, Limited. The
+  milk in this case is placed in an earthenware jar, and is
+  sterilised by placing in a saucepan of water and boiling
+  it. The culture is added after cooling, the period of
+  incubation being about six hours.]
+
+The containing vessel is of tin or aluminium, and has two stands, the
+high one for hot and the low one for cold weather, as in the latter
+case greater heat is needed to maintain the incubating temperature. The
+milk is placed in an earthenware jar and is sterilised by placing it in
+a saucepan of water and boiling it; continuing the boiling for half an
+hour. It is allowed to cool to about 98° F., and placed in the
+incubator, culture added, and the lamp lighted, the cover of the
+incubator being kept on. The period of incubation is given as six hours.
+To prepare the next day's supply a tablespoonful of the soured milk is
+retained and used instead of the culture. This may be continued for
+fourteen days, when a fresh start with culture is necessary. The soured
+milk will keep for thirty-six hours. Capacity, one and one half and two
+pints; also a large size for family use.
+
+For the preparation of soured milk on a small scale, one of the various
+forms of vacuum flasks now on the market may be used with satisfactory
+results. A little cold water must be poured into the flasks, and warm
+water added, until, by means of three to four changes, boiling water can
+be safely poured in without cracking the flask.
+
+This boiling water must be allowed to remain in for about twenty
+minutes, and then replaced by freshly boiled milk that has been cooled,
+so that its temperature in the flask is about 105° F. The culture of
+lactic organisms should then be added, the opening of the flask plugged
+with clean cotton-wool, and the cap screwed on.
+
+In an actual test, the temperature of the milk placed in such a flask
+was 105° F., at 7.30 P.M., and had dropped to 93° F. by 9 A.M., the
+following day. The milk was curdled, and possessed the normal acid taste
+of such cultures.
+
+The different types of apparatus are all quite simple, and it would be
+easy to make something at home. Get two round tins, the one less in
+diameter by from two to three inches than the other, put one or two
+pieces of wood across the bottom inside the larger tin, and fill up the
+space between with cotton-wool, which is an excellent non-conductor of
+heat. Place the smaller tin centrally inside the larger one. Fix three
+or four distance pieces of wood in the space between them, fill up with
+cotton-wool, leaving a little space at the top to permit the lid of the
+smaller tin to be fixed on. The boiling-water vessel may be a tin
+saucepan with a lid, but no handle, and its proper place would be on the
+bottom of the inner tin. A tripod stand made of three pieces of wire
+bound together, and with legs reaching past the hot-water vessel to the
+bottom of the tin, would support a false bottom of tin forming the shelf
+on which the vessels of milk to be treated would rest. These might be
+tumblers covered with tin lids. To prevent radiation through the lid of
+the inner tin, a thick pad or hood of cotton-wool packed between cloth
+would be placed over the top. A little experimenting would be necessary
+to determine the quantity of boiling water required to maintain the
+proper temperature.
+
+The soured milk obtained in the above manner is of the consistency of
+ordinary buttermilk; a separation of whey frequently takes place, and
+this may be poured off if desired. The taste and flavour should be
+pleasantly acid and agreeable, and both are distinctive enough to give a
+good idea of the purity of the product. In many places a more
+concentrated article is made by boiling down the milk to one half or one
+third of its bulk, and then fermenting it in the ordinary way. A kind of
+thick pudding is thus obtained, which is highly recommended both as an
+agreeable article of food and as a stronger medium for the support of
+the germs it is the purpose of the sour milk treatment to introduce
+into the digestive system.
+
+The cultures for making soured milk can now be had from all the leading
+wholesale and retail chemists, with directions as to the quantities to
+be used.
+
+It is very necessary that the milk used should be not only fresh and
+good, but also free from chemical preservatives. The effect of these is
+to inhibit the growth and development of bacteria, and they have
+therefore an injurious influence on the special lactifying germs it is
+our object to cultivate. Preservatives are now not nearly so much used
+as they were, a few years ago, and there should be no difficulty in
+obtaining milk free from them.
+
+For keeping both fresh and soured milk good a small ice-chest is an
+excellent device. The germs which are continually dropping into milk
+kept in open vessels in the air, even in cleanly surroundings, are
+mostly kept out in the close ice-chest, and the low temperature prevents
+in a natural way the development of the bacterial germs already in the
+milk. For the preservation of all kinds of foods the ice-chest is a
+capital investment, not to mention the benefit of having cooled drinks,
+etc., as required. They manage things well in this respect in the United
+States, where ice is regarded as a necessity in the summer time by even
+the poorest people, and is delivered with the same regularity as the
+milk.
+
+It is necessary to utter a word of warning as to certain forms in which
+the sour milk bacillus is being offered to the public. It is being
+compounded with sugar, chocolate, and other articles, and sold in the
+form of sweets, etc. There is no reliable proof that these preparations
+are valuable. Certainly, sugar is a medium in which the lactifying germs
+can live, but the quantity so introduced into the system must be very
+small compared with what is obtained from properly fermented milk. It
+takes some time, even with strong cultures, to fix the acid-producing
+germs in the large bowel where they are wanted, and until proper
+evidence is forthcoming that confectionery preparations are efficacious
+we would recommend that only the regularly fermented milk be used. It
+would save trouble, no doubt, to treat oneself with a few chocolate
+creams containing the necessary germs daily, but if the matter is taken
+up seriously it will be better to take some pains and stick to methods
+the efficacy of which has been demonstrated, leaving the others until
+their _bona fides_ has been proved. There are always enterprising firms
+who are prepared to simplify things for us, but we must make sure that
+their simplifications are warranted.
+
+
+
+
+CHAPTER VII
+
+THE PREPARATION OF SOURED MILK IN THE DAIRY
+
+
+There is a tendency in certain medical quarters to discourage the use of
+soured milk "made for profit." This view leaves out of account the fact
+that besides being of value in medicine, the article in question is also
+an excellent food, which, as we have seen, has been consumed by
+multitudes of people for ages in many parts of the world. There seems
+also to be satisfactory evidence that a larger percentage than usual of
+the people who make soured milk a staple of diet attain to a ripe old
+age. How does it become such a dangerous thing the moment the doctors
+get it into their hands? Of course if a man has an acute disease he
+places himself entirely in the hands of his medical man, and eats what
+is prescribed for him, or at least he ought to do so, and if he makes
+such a submission he is entitled at least to the comfort of being able
+to feel that his doctor is free from unreasonable prejudices. For the
+implication that an article "made for profit" is naturally suspect casts
+an unwarranted stigma on a large number of honourable people. There are
+dishonest tradesmen just as there are dishonest and careless doctors,
+but to saddle a whole class with the offences of a few would not be a
+justifiable proceeding in either case. Besides, it is not to the
+interest of the manufacturing chemist or the dairyman to turn out
+spurious cultures or bad soured milk, and on the whole we see no reason
+why they should not engage in the business.
+
+The widespread use of soured milk in other countries as a regular
+article of diet seems to indicate that all manner of people, except
+those suffering from diseases which necessitate medical regulation of
+diet, might with probable benefit to themselves add this article to
+their food list; and it looks as if a good many of them intend doing so,
+even if scandalised doctors threaten "to abandon the cure."
+
+The dairyman who knows his business does not need to be told of the care
+which is necessary to keep milk in good condition. The merely commercial
+consideration of avoiding loss has made him ready to inquire into the
+best means of prolonging the life of milk as a merchantable article.
+For a time he relied on chemical preservatives, but their day is now
+almost over, and filtration, pasteurisation, and cold storage have taken
+their place. Any one conversant with the trade knows how widely these
+methods have been adopted of late years; we may, therefore, assume that
+the average dairyman has at his command milk suitable for the incubation
+process.
+
+The demand for soured milk is not as yet a very large one, and the
+apparatus so far developed for its production is meant for the treatment
+of small quantities. After describing the principal appliances at
+present in the market we propose to make some suggestions as to the
+construction of larger apparatus.
+
+A firm which has given great attention to the question of maintaining
+fixed temperatures is that of Messrs. Charles Hearson & Co., Ltd. Their
+incubators for chicken hatching are known all over the world; and their
+appliances for biological incubation are very generally used in
+bacteriological laboratories. With such experience it was natural that
+they should turn their attention to soured milk apparatus, and the
+result is the "Lactobator" (Figs. 50 and 51).
+
+  [Illustration: FIG. 50.—"Lactobator" made by Messrs.
+  Charles Hearson & Co., Limited, which is used for the
+  incubation of pure culture in milk in a fairly large way.
+  The illustration shows the "Lactobator" closed.]
+
+  [Illustration: FIG. 51.—Messrs. Hearson & Company's
+  "Lactobator," showing the internal arrangements.]
+
+A copper vessel made to contain water has placed in it a stoneware jar
+which holds two gallons of milk; on the top is a lid which carries a
+thermometer for indicating the temperature of the milk. Heat is supplied
+by a gas ring under the copper vessel; and in the gas supply is the
+patent thermostat made use of by Messrs. Hearson also in their
+biological and poultry incubators, in which a capsule containing a
+liquid arranged to boil at a certain predetermined temperature is the
+regulating factor. When the liquid boils, the capsule expands, and by
+certain mechanical devices regulates the gas supply so as to produce
+exactly the temperature required.
+
+The procedure is as follows: The jar is filled with milk, and water is
+run into the copper vessel by the funnel until it runs over at the
+overflow pipe. The thermostat is lifted off and the full gas supply
+allowed to pass to the burner, the temperature of the milk brought up to
+180° F. and maintained for half an hour at this figure. The gas is then
+turned off, and cold water run through the funnel until the temperature
+of the milk registers 95° F. The culture is added, the lid replaced, and
+the thermostat put into the pocket at the side of the vessel; the gas
+relighted, and when the temperature reaches 100° to 106° F. the
+capsule of the thermostat will expand and close the gas to a peep, which
+is just sufficient to maintain the temperature within the above limits.
+After eight hours the incubation is completed.
+
+Edgar's patent apparatus, the "Lactogenerator," as provided by the Dairy
+Supply Co., Ltd., is shown in Fig. 52.
+
+  [Illustration: FIG. 52. Edgar's "Lactogenerator"]
+
+The milk is placed in a tinned copper-jacketed vessel and water run in
+through a vertical pipe until it runs off at the overflow. Two gas
+connections are required with cocks on each, the one to heat up the milk
+to the boiling point and maintain it at this for thirty minutes. A
+skimmer which has been placed in the milk lifts out the coagulated
+protein and albumen which rise to the top. The cock is then shut and
+cold water run through the jacket till the thermometer shows 90° F.,
+when the culture is added, and the other gas supply with the regulator
+turned on, and the temperature is automatically maintained at about 90°
+F. Time of incubation eight to nine hours. It is recommended to turn
+cold water into the jacket at the end of the period to prevent
+overincubation.
+
+A somewhat similar apparatus is that of the Willows Refrigerating Co.,
+Ltd. (Fig. 53), with the exception that it has no automatic heat
+regulator. It is made of tinned steel, and the operations are the same,
+but the sterilising temperature (obtained by a gas ring or hot plate) is
+given as 180°, and the incubating temperature 100° to 104° F. for a
+period of twelve hours. Presumably this temperature is maintained by a
+small gas jet or other similar source of heat. The capacity is two
+gallons.
+
+  [Illustration: FIG. 53
+
+  Apparatus of the Willows Refrigerating Co., Ltd.]
+
+In the apparatus hitherto described the milk is sterilised in bulk, and
+is filled into bottles or jars after incubation, which is not a
+desirable thing to do, unless the soured milk is for immediate
+consumption, as there is likely to be contamination with injurious germs
+from the atmosphere. In the domestic apparatus the milk is usually
+incubated in covered jars in which it can be kept until required for
+use, and the practice on the larger scale should be the same.
+
+The Dairy Outfit Co., Ltd., have recognised this in their "Lacto"
+apparatus (Fig. 54).
+
+  [Illustration: FIG. 54
+
+  "Lacto" Apparatus of the Dairy
+  Outfit Co., Ltd.]
+
+A cylindrical vessel is set loosely on a stand, beneath which is a lamp
+calculated to maintain the incubating temperature. The milk is placed in
+bottles with metal screw tops, and these are put into the cylindrical
+vessel; water is run in round them through the side funnel, the vessel
+lifted off the stand, and heated to sterilising point on a stove. Cold
+water is then run in through the funnel until the temperature is low
+enough for incubation. Culture is added to each bottle and the lids
+screwed on, the vessel lifted on to its stand, and the lamp lighted. The
+cover of the apparatus has a thermometer fixed on it.
+
+On the large scale the treatment of the milk would take place entirely
+in the jars in which it would be sent out, and the sterilisation and
+incubation would be conducted in different pieces of apparatus. The
+sterilisation would be effected either (1) by direct steaming, or (2) by
+hot water heated by steam. Fig. 55 shows the first type of
+sterilisation. The tank is of wrought iron or steel with strengthening
+pieces of angle iron. The door, with pulleys and counterweight for easy
+handling, is fastened steam-tight by hinged bolts. The apparatus is
+mounted on a stand at a convenient height for handling the bottles; and
+in front is another stand with channel iron rails to take the waggon in
+which the bottles or jars to be sterilised are packed. When the door is
+fast, steam is turned on, and regulated to produce the proper
+temperature by the thermometer fixed in the shell, in which a pressure
+gauge is also secured. After sterilising, the door is opened and the
+waggon drawn forward to the outside, allowed to cool, or removed
+elsewhere to cool, and allow space for a new charge.
+
+  [Illustration: FIG. 55.—Sterilising Apparatus for
+  sterilising milk on the large scale. The bottles of milk
+  are sterilised, and the culture can then be added, and the
+  incubation allowed to proceed in an insulated chamber.]
+
+The second method of sterilising is by hot water, as in Fig. 56. The
+bottles or jars are placed on a perforated false bottom in the
+rectangular tank, water run in up to the necks, and steam turned on; the
+lid is fastened with hinged and hooked bolts; a thermometer fastened in
+the lid, and with a long stem enclosed in metal, indicates the
+temperature. At the end of the sterilising process cold water is turned
+on, and at the same time the overflow water cock is opened; the cold
+water gradually reduces the temperature, and the incubating point is
+quickly reached.
+
+  [Illustration: FIG. 56 Another Method of Sterilising
+  (Dairy Supply Co., Ltd.).]
+
+Incubation in bottles or jars, sterilised in these ways, can best be
+conducted in an insulated room, with say, six inches of silicate cotton,
+granulated cork, or washed cow hair packed between two-inch by six-inch
+battens, covered with matching on either side, and lined with sheet
+zinc. It would be an advantage to have an air-lock or anteroom into
+which the waggons or trays of sterilised jars could be run, and the door
+of the anteroom closed before the door of the insulated room is opened.
+This would tend to prevent variations of temperature in the room, and
+also, by checking free communication with the outside air, decrease
+contamination. The waggons of jars would be run in, and culture added to
+each jar by a sterilised pipette. The atmosphere of the room would be
+kept pure by running in air frequently through a filter of moist
+cotton-wool by means of an electric fan, and at intervals the interior
+would be sterilised by the use of formalin vapour.
+
+
+  [Illustration: _Details of an American Apparatus for
+  Preparing Soured Milk_
+
+  FIG. 57
+
+  The figures give diagrams A, B, C, and D of an apparatus
+  useful for the preparation of lactic foods. The incubating
+  can A, is made of block tin, and is intended to contain
+  the milk. B, the warm water container, should be a stout
+  walled vessel with a circular aperture in the lid, through
+  which the incubating can may be passed, and clamped down
+  as in C.
+
+  B is fitted with three stout iron legs, which should be
+  sufficiently long to allow of a small lamp or gas-jet
+  being placed beneath the container to maintain a uniform
+  temperature.
+
+  D gives an external view of the apparatus.
+
+  For the preparation of soured milk, separated milk is
+  placed in the incubating can, and heated up to 100° C.
+  (212° F.) for thirty minutes. It is then allowed to cool
+  to room temperature, and the culture, or tablet containing
+  the lactic acid bacteria, is then added, and thoroughly
+  stirred for a minute or so. The can is then immersed in
+  the warm water container and kept at a temperature of 86°
+  F. to 104° F., according to the organisms used, for ten to
+  twelve hours. By the end of this time the milk ought to be
+  converted to a jelly-like mass, and after being stirred
+  vigorously for a short time, may be cooled on ice, and is
+  then ready for consumption.]
+
+The incubating temperature could very conveniently be maintained by an
+electric radiator, and as the insulation would largely prevent leakage,
+the amount of electric current used would not be large. The regulating
+apparatus might consist of a thermometer with platinum wires fused
+through the stem at the proper temperature, say 100° F. When the mercury
+rises to this figure it will complete the circuit of a battery which
+will actuate certain well-known devices for turning off the current
+which actuates the radiator. In this way a very fine automatic
+arrangement would be achieved. Steam pipes might be used instead of the
+radiator, and the thermometer above described could be used in this case
+also, with appliances to cut off the steam.
+
+On the large scale, labour-saving appliances, such as the mechanical
+brush jar and bottle washer, and the automatic filler for jars or
+bottles, would be employed, and an overhead trackway for carrying the
+trays of jars from the steriliser to the incubator would be a great
+convenience. A further adjunct of considerable importance would be a
+cold room, worked either by ice or a refrigerating machine, in which the
+jars could be stored after incubation, so as to arrest the process of
+lactification, and maintain the soured milk in good condition until
+required for use.
+
+
+
+
+CHAPTER VIII
+
+SOURED MILK IN HEALTH AND DISEASE
+
+
+When people are ill the best thing they can do is to place themselves in
+the hands of the doctor, who will try to regulate their lives, including
+their diet, in accordance with the conditions which science suggests as
+the most likely to lead to their recovery.
+
+It is not the aim of this book to teach persons who should be under
+medical treatment to doctor themselves; soured milk may or may not be
+beneficial in their case—that is for the medical man to say; and
+further, if it should be beneficial the doctor ought to have its
+preparation under his control. Slight differences in quality and purity
+may count for much in cases of acute disease, differences which might
+not matter to the person who requires no medical attention, and who
+consumes the article as a health-giving food. A considerable body of
+evidence is already on record as to the potency in certain cases of
+soured milk as a curative agent, and it seems to have taken its place in
+medicine as a recognised remedy.
+
+There is a wide field of usefulness, however, outside of the strictly
+medical one. Professor Metchnikoff has collected many striking examples
+of individuals and peoples inhabiting different parts of the world, who
+thrive, and in many cases attain to a great age, and whose diet consists
+largely of soured milk. He has made a wide and general inquiry into the
+causes which tend to shorten life, and makes out a strong case in
+support of the view that in many cases this is the result of what is
+called auto-intoxication or self-poisoning. In man and in the mammalia
+generally, the colon or large intestine is very largely developed; this
+organ is not of much value in the digestion of food, and seems to be
+chiefly a receptacle for waste material; it is, as a rule, extremely
+rich in bacterial flora, which produce putrefactive changes in the waste
+material. As a result various poisonous principles are evolved, and
+these find their way into the blood, accompanied frequently, there is
+every reason to believe, by the injurious bacteria themselves. In this
+way many diseases and ailments are produced which shorten life. The
+inquiry then naturally turns to what is the best way of dealing with
+this state of matters. It is known that the bacteria referred to
+flourish best in alkaline or at least non-acid surroundings, and it is
+known that these conditions very frequently exist in the large
+intestine. Acids are the best antiseptics; they have been used from time
+immemorial as preservatives; pickles are preserved in vinegar or acetic
+acid, and when milk is allowed to sour under proper conditions, the
+germs of putrefaction are destroyed or their activity inhibited, and it
+keeps a considerable time. Doubtless, in hot countries, it was this
+property of lactic acid which first led to milk being artificially
+soured with a view to its preservation as an article of food. So
+powerful is lactic acid in this respect that it is a custom in some
+countries to preserve meat by placing it in soured milk.
+
+How can acids be applied so as to control the bacterial flora of the
+large intestine? Not in the ordinary way, because, when administered
+through the mouth, they are used up long before they can penetrate to
+the colon. The brilliant idea occurred to Professor Metchnikoff, of
+administering acid-producing germs which might work their way through
+the digestive system, and, reaching the large intestine, produce the
+acid required. After much experimenting the bacillus of Massol,
+_Bacillus bulgaricus_, was adopted as the most suitable. The Bulgarian
+bacillus is an extremely vigorous one, multiplying with great rapidity,
+and persisting in conditions that would be inimical to other microbes.
+The growth and development of bacteria is interfered with by the
+products of their own activity; thus, ordinary lactic-acid-producing
+organisms die when a certain amount of lactic acid has been developed;
+the same fate overtakes the Bulgarian bacillus, but it survives longer
+and is able to produce as much as two and one half per cent. of lactic
+acid in milk before it ceases operations. It seemed therefore the most
+likely to be able to survive the journey through the digestive system.
+Experiments fully bore out this supposition, as no great difficulty was
+encountered in naturalising the Bulgarian bacillus in the large
+intestine, not only in milk cultures, but grown in solution of malt,
+bouillon, etc. It thrives in all kinds of sugar, and therefore can be
+administered in a variety of media, very beneficial results following in
+many cases. Direct tests showed a large reduction of the injurious
+intestinal flora when the Bulgarian bacillus had been naturalised in
+the colon, and the bacillus persisted long after it had ceased to be
+administered. Specialists who have taken up the subject report the cure
+of many ailments through the agency of soured milk, and it seems to have
+entered upon a lengthening career of medical usefulness.
+
+The fact of so many old people being found in countries where soured
+milk is a staple of diet naturally raises the question as to whether its
+general use in other countries might not have a beneficial effect on
+health and longevity. Its usefulness as a remedial agent in certain
+diseases is already demonstrated; is there not a strong probability,
+amounting almost to a certainty, that its consumption by people in
+health would tend to ward off many ailments and prolong life? Of course
+there will be some for whom it is not suitable; there are people who
+cannot eat strawberries without discomfort, but no one thinks of
+prohibiting the general use of the fruit on that account. In the matter
+of diet the person in health, if he exercises ordinary care, may be left
+to find out for himself what suits him. The soured milk remedy is not a
+disagreeable one, as, when properly prepared, the article forms both a
+pleasant and refreshing article of diet. The question of getting the
+right article, however, is a very important one. Milk is a splendid
+rearing ground for many bacteria, some of which are very injurious;
+among these may be pathological germs, the seeds of tuberculosis,
+enteritis, etc. The danger with soured milk is, that in the process of
+culture we develop the best condition for the increase of these when
+they preponderate, or when, through the use of bad cultures, the
+lactic-acid-producing bacteria are absent, or present only in small
+numbers. By the thorough boiling of the milk, we get rid of all living
+bacteria and nearly all spores or germs, and by scrupulous cleanliness
+in the vessels used—scalding or even boiling them, and allowing them to
+dry naturally in an inverted position—we greatly diminish the
+probability of infection with fresh injurious germs from the atmosphere.
+All depends on the purity of the culture employed; this can now be
+obtained, prepared in the most careful manner, from wholesale chemists
+making a speciality of its manufacture.
+
+As we have seen, even the Bulgarian bacillus is ultimately killed by the
+products of its own activity, and the natural corollary is, that the
+life of cultures cannot be a long one. Only those cultures should be
+bought which are labelled with the date to which they are guaranteed to
+maintain their efficiency. With fresh good milk, careful boiling,
+scalding, and cleanliness with regard to the containing vessels, and the
+means of maintaining the incubating temperature for ten or twelve hours,
+there is not the slightest difficulty in preparing perfectly reliable
+soured milk. There are simple tests which will sufficiently guide the
+experimenter; the soured milk should not be too acid to the taste, and
+it has a flavour of its own by which its quality can be recognised. The
+litmus test-papers mentioned in the chapter on the chemistry of milk are
+very useful; both the red and the blue papers should be obtained and
+used first of all in testing the quality of the fresh milk. After
+incubation the soured milk should turn the blue paper decidedly red; if
+this does not occur, test it with the red paper; if the latter turns
+blue it is proof that the wrong fermentation has taken place—that
+putrefactive germs have gained the upper hand. The most probable
+explanation is, that the culture is bad, the Bulgarian bacillus is not
+present, or if so, only in small numbers. With these simple tests,
+combined with proper care, one cannot go far wrong. The Eastern nations
+who prepare soured milk in various forms do not exercise the care we
+have predicated, but they seem to make the article of fairly constant
+and good quality. It has been suggested in explanation that, as the
+ordinary flora differs in different countries, the bacterial flora
+varies in a similar manner, and that in these Eastern countries
+injurious bacteria are not so prevalent in the atmosphere as they are
+with us.
+
+It is also said that the flavour of the soured milk prepared in Bulgaria
+is quite different from that prepared in Paris, London, or New York; one
+reason probably is that the "maya" or ferment used in Bulgaria contains
+several other organisms besides the Bulgarian bacillus, which raises the
+question whether a pure culture of one bacillus is the best to use.
+
+Professor Metchnikoff found that this bacillus alone had certain
+defects; it attacks fat and is apt to give a tallowy taste when cream is
+present in the milk. He therefore associated with it another
+lactic-acid-producing organism, and this combination is the basis of his
+culture called "lactobacilline." The presence of yeasts, which occur in
+the Eastern ferments, has been advocated by some; the yeast in
+association with the lactic organisms produces a small amount of
+alcohol. The question of the composition of the culture will have to be
+fought out by the experts, but meantime, if we go to the right source,
+we have good enough cultures to go on with.
+
+A good deal can be said for the use of skimmed or separated milk instead
+of whole milk. Cream as a rule contains far more bacteria than the rest
+of the milk, and we therefore start from a surer foundation when it is
+removed; besides, the mechanical separator, now so largely used, removes
+slime and other impurities from the milk, and these also are hotbeds of
+bacteria.
+
+Soured milk may be taken at any time, the first thing in the morning,
+before or after meals, or the last thing at night. The quantity will
+vary with the individual, but from half a pint to a pint is a fair
+amount for daily use. If one wishes to have the maximum effect it is
+necessary for the time being to curtail the use of butcher's meat and
+substitute fish, yolk of eggs, and other similar foods; not much alcohol
+should be taken, and smoking might be reduced to a minimum. Those who
+cannot take even skimmed milk may use whey in which to cultivate the
+bacillus; it is not desirable to employ the whey which has been
+separated by the use of rennet, as in cheese- or junket-making. A better
+article is obtained by adding a very small quantity of pure hydrochloric
+acid to milk which has been boiled, and then filtering through a sieve,
+which retains the curd while the liquid whey passes through; a pinch of
+soda is added to neutralise the excess of acid, and, after boiling, the
+liquid should turn red litmus paper blue; it is then ready for the
+addition of the culture and incubation in the same manner as with milk.
+A solution of malt—the extract dissolved in hot water is
+convenient—may also be used instead of milk, and strongly malted bread
+or biscuits are excellent to take with the soured milk or cultures in
+other mediums, to supply food for the bacillus in the form of malt
+sugar. Other sugars, cane or grape, are also very useful, and may be
+taken in the form of fruit juices, syrups, confections, jams, sweet
+puddings, etc.
+
+We lay stress on the use of soured milk or other cultures of the
+Bulgarian bacillus by people in health as a probable preventive of
+disease and a possible agent in the lengthening of life, but it may be
+of interest to give a short account of its use by medical men in the
+treatment of various ailments. An English authority on the subject, Dr.
+Herschell, states that the symptoms of the poisoning of the system by
+the toxic substances produced by injurious bacteria in the large
+intestine may include headaches, misery and depression of spirits,
+drowsiness and stupor, giddiness, dimness of sight and dizziness,
+fatigue without obvious cause, both of the muscles and brain, fear,
+panic, and nervousness, disagreeable sensations in the limbs or face,
+such as numbness, tingling, or prickling, crawling sensation of weight
+or of heat or cold, dyspepsia of the sort where there is a deficiency of
+hydrochloric acid and pepsin in the gastric juice, accompanied by
+flabbiness and loss of power in the muscles of the stomach, and
+characterised by flatulence, nausea, loss of appetite, with discomfort
+and weight after food, furred tongue, emaciation, earthy colour of the
+skin, offensive perspiration and the other signs of biliousness,
+enlargement of the liver, and anæmia. These symptoms may have other
+causes, and when one or several of them are present a chemical and
+physical examination of the urine and fæces is necessary to prove that
+they have resulted from auto-intoxication. When this is shown the
+soured milk treatment is indicated, and many striking cures are detailed
+as witnesses to its efficacy. The liver and kidneys are the natural
+guardians of the body against the toxines we are speaking of, and
+frequently they are over-strained; the soured milk treatment greatly
+lightens their load. In malignant disease of the stomach, soured milk
+will frequently be retained when all other foods are rejected. In cases
+of neurasthenia and gout it has also proved of value, and in the
+"run-down" condition which is so common in middle life. Chronic
+diarrhœa and certain forms of constipation have in numerous instances
+yielded to the treatment, the whey culture being usually found the most
+suitable. Then, in some forms of anæmia, the lactic acid cultures have
+proved most successful, and, as a means of rendering the
+gastro-intestinal track aseptic previous to operations, they have proved
+of considerable value.
+
+If all this has been accomplished in a year or two, what may not we look
+forward to in the future when more extended use and experiment shall
+have more fully exhausted the possibilities of the cure? But if we
+follow the example of the different nations who have so long used
+soured milk as a regular article of diet, does it not seem probable that
+we may eliminate some, at least, of the causes of ill-health that call
+for the intervention of the doctor?
+
+The human organism is by no means perfect; we have within us many
+defective parts, and some organs whose working seems to be against the
+welfare of the economy. It has now been clearly shown that one of the
+chief of these is the large intestine, as to the use of which only vague
+and unsatisfactory theories have been formed. There can be no doubt as
+to the damage which it frequently inflicts on the system, and, thanks to
+the researches of Professor Metchnikoff and other investigators, we seem
+to be in possession of a natural remedy which is sufficient to deal with
+the evils it produces.
+
+
+  FOOTNOTES:
+
+  [1] _Discoveries in Nineveh and Babylon_, by Layard, chap.
+  xiii.
+
+  [2] Ex. xviii. and xxiii.; Lev. ii. and xi.
+
+  [3] _Encyclo. Biblica._
+
+  [4] Burckhardt and Doughty.
+
+  [5] _Annals of Dairying in Europe_, by Loudon M. Douglas.
+
+  [6] Burckhardt, _Bedouins_.
+
+  [7] This word is spelt in a great many ways by different
+  writers: _Yoghourt_ would seem to be the one most
+  favoured.—AUTHOR.
+
+  [8] _Damascus and Palmyra_, by Chas. G. Addison, 1838.
+
+  [9] _Travels in Syria and the Holy Land_, by Burckhardt,
+  1822.
+
+  [10] _Lands of the Saracens_, by B. Taylor.
+
+  [11] _Travels through Sweden, Finland, and Lapland and to
+  the North Cape in the years 1798 and 1799_, by Joseph
+  Acerbi, 1802.
+
+  [12] Letter to the author, from Mr. H. Cavendish Venables,
+  British Vice-Consul at Varna.
+
+  [13] _One Hundred and Twenty Years of Life_, by Reinhardt;
+  _The Secret of Longevity_, by an F.R.M.S.
+
+  [14] _Foods, their Composition and Analysis_, by A. W.
+  Blyth.
+
+  [15] _Dictionary of Applied Chemistry_, by T. E. Thorpe,
+  C.B.
+
+  [16] _Koumiss or Fermented Mares' Milk and its Uses, and
+  the Treatment and Cure of Pulmonary Consumption and Other
+  Diseases_, by L. Carrick, M.D., 1881.
+
+  [17] _Transactions of the Royal Society of Edinburgh_,
+  vol. i.
+
+  [18] Clarke's _Travels_, 1810.
+
+  [19] 1845.
+
+  [20] _Dictionary of Applied Chemistry_, by Thorpe.
+
+  [21] A leathern bottle.
+
+  [22] "I have brought forward Tchembulatof's receipt, which
+  differs from Bogoyavlensky's in the use of a larger
+  quantity of millet-flour, and in the boiling of the latter
+  apart from the milk. Dr. Postnikof's plan is the
+  following: Half a pound of millet-flour and a quarter of a
+  pound of malt are mixed with a sufficient quantity of
+  honey to form a paste, which is put into a clean jar,
+  covered with a linen cloth, and placed on a warm stove.
+  The mass soon begins to rise, and is then taken out,
+  wrapped in a piece of muslin, and dropped into a clean
+  earthenware vessel, containing about a quart of new mares'
+  milk, which is placed in the same temperature that the
+  paste was kept in. As soon as signs of fermentation begin
+  to show themselves in the fluid, the paste must be
+  removed, while the milk, after being stirred, should be
+  left in the same temperature till bubbles appear (only in
+  very small quantities) on its surface. The ferment is then
+  ready."
+
+  [23] _Food and the Principles of Dietetics._
+
+  [24] _Food and the Principles of Dietetics_, by Robert
+  Hutchison, M.D.
+
+  [25] _Bacteria in Milk and its Products_, by Conn.
+
+  [26] _Dict. App. Chem._, Thorpe.
+
+  [27] _Nature_, July 23, 1884.
+
+  [28] _The Exploration of the Caucasus_, by Duncan W.
+  Freshfield, 1896.
+
+  [29] Quoted by George M. Sternberg, M.D., LL.D.,
+  _Text-Book of Bacteriology_, 1898.
+
+  [30] _Encyclo. Biblica._
+
+  [31] Conn.
+
+  [32] _Cyclo. of Biblical Lit._, M'Clintock and Strong, and
+  Burckhardt's _Arabia_.
+
+  [33] _The Indian Medical Gazette_, Sept., 1909, "A New
+  Lactic Acid producing Streptothrix," by Gopal Ch.
+  Chatterjee, M.B.
+
+  [34] In their studies on Leben in the _Annales de
+  l'Institut Pasteur_ of 1899, Rist and Khoury, in speaking
+  of the amount of lactic acid produced by _Streptobacillus
+  lebenis_ in milk, say "Nous avons mesuré cette acidité
+  dans une culture sur petit lait de vingt-quatre heures;
+  elle était .261 grms. per cent. exprimée en acide
+  lactique," which will make the amount of lactic acid
+  produced in one litre of milk 2.61 grms. The production of
+  this small amount of lactic acid does not tally with the
+  ordinary view of the vigorous lactic-acid-producing power
+  of the bacillus.
+
+  [35] _Prolongation of Life._
+
+  [36] _Prolongation of Life._
+
+  [37] An accurate census of Bulgaria is being prepared and
+  will exhibit the cases of long life in that country.
+
+  [38] See A. Rosam, _Österreichische Molkerei Zeitung_, 15,
+  p. 31.
+
+  [39] _Revue générale du Lait_, vii., pp. 8 and 9 (letter
+  from Dr. Otakar Laxa of Prague, Bohemia, to the author).
+
+  [40] _On the Prolongation of Human Life_, by Élie
+  Metchnikoff; also _The Century Magazine_, Nov., 1909, "The
+  Utility of Lactic Microbes," by the same author.
+
+  [41] _Century Magazine_, Nov., 1909.
+
+  [42] See _Annals of Dairying in Europe_, by Loudon M.
+  Douglas.
+
+  [43] Adapted from a report by Robert E. Turnbull, in _Live
+  Stock Journal_.
+
+  [44] _Facts about Milk_, by R. A. Pearson, B.S.,
+  Washington.
+
+  [45] _Care and Handling of Milk_, Marshall and Wright,
+  Bulletin 221, Michigan, 1904.
+
+  [46] _Journal of the Royal Society of Arts_, March 6,
+  1908—"Modern Dairy Practice," by Loudon M. Douglas.
+
+  [47] Skolotowski, _Wratsch_, 1883 (Russian), from
+  Codwyssozki.
+
+  [48] Podowyssozki, _Zeitschr. f. diat. u. physik.
+  Therapie_ vol. v., 1901, p. 570.
+
+  [49] Hammersten, _Jahresb. u. d. Fortsch. d. Tierchem_,
+  1886, Bd. 16, p. 163.
+
+  [50] Essaulow, _Dissert. Moscow_, 1895, _Abstr., Koch's
+  Jahresb._, 1895, Bd. 6, p. 222.
+
+  [51] Kern, _Bulletin Soc. des Naturalistes de Moscow_,
+  1881, 3, p. 141.
+
+  [52] Krannhals, _Deutsch. Arch. f. Klin. Med._, 1884, Bd.
+  35, p. 18.
+
+  [53] Beijerinck, _Centralbl. Bakt. Par._, 1889, Bd. 6, p.
+  44.
+
+  [54] Scholl, _Die Milch_, Wiesbaden, 1891, p. 38.
+
+  [55] Adametz, _Centralbl. Bakt. Par._, 1889, Bd. 5, p.
+  116.
+
+  [56] Freudenreich, _Landw. Jahrb. d. Schweiz._, 1896, vol.
+  x., p. 1.
+
+  [57] Nikolaiewa, _Annals of the Botan. Lab. of the Med.
+  Inst. for Women_, No. 10. St. Petersburg, 1907.
+
+  [58] Kuntze, _Centralbl. Bakt. Par._, 1909, 24, p. 101.
+
+  [59] See Chap. II.
+
+  [60] Rubinsky, _Centralbl. Bakt. Par. II._, 1910, vol.
+  xxviii., p. 161.
+
+  [61] Biel, _Jahresb. ü. d. Fortschr. d. Tierchem_, 1886,
+  16, p. 159.
+
+  [62] Allik, _Dissertat. Dorpat._, 1896, 19, p. 303.
+
+  [63] Fleischmann, _Lehrb. d. Milchwirtschaft_, 2d edition.
+  Bremen, 1898.
+
+  [64] Rist and Khoury, _Annal. Pasteur_, 1902, 16, p. 65.
+
+  [65] Guerbet, _Comptes Rendus_, 1906.
+
+  [66] Weigmann, _Lafar's Handb. d. Techn. Mykol._, 2d
+  edit., 1905, vol. ii., p. 134.
+
+  [67] Emmerling, _Cent. Bakt. Par._ 1898, vol. iv., p. 418.
+
+  [68] Lindner, _Mikroscop. Betriebscontrolle, i. d.
+  Gärungsgew_, 3d edit., Berlin, 1901.
+
+  [69] Kalantharianz, _Dissert. Berlin_, Abs. in _Koch's
+  Jahresb._, 1898, Bd. 9.
+
+  [70] Luerssen and Kühn, _Centralbl. Bakt._
+
+  [71] Piorkowski, _Sitzungsber. der Berl. med. Ges._, Nov.,
+  1907.
+
+  [72] Metchnikoff, _The Prolongation of Life._
+
+  [73] Grigoroff, _Revue Médicale de la Suisse Romande_,
+  1905, p. 10.
+
+  [74] Grixoni, _Abstr. Cent. Bakt. Par._ 11, 15, p. 750.
+
+  [75] Freudenreich and Jensen, _Cent. Bakt. Par._ 11, 1897,
+  3, 545.
+
+  [76] Moro, _Wien. klin. Wochenschr._, 5, 1900.
+
+  [77] Makrinoff, _Cent. Bakt. Par._ 11, 1910, vol. xxvi.,
+  p. 374.
+
+  [78] White and Avery, _Cent. Bakt. Par._ II, 1909, vol.
+  xxv., p. 161.
+
+  [79] Hastings and Hammer, _Research Bull., Wisconsin
+  Experimental Station_, 6, 1909.
+
+  [80] Boutroux, _Comp. Rend._, 86, 1905, 605.
+
+  [81] Richet, _Comp. Rend._, 86, 1905, 550.
+
+  [82] Koning, _Milchw. Zentralbl._, 1905, 1, 280.
+
+  [83] Heinemann, _Centralbl. Bakt. Par._ 1908, 21, 57.
+
+  [84] Chap. I.
+
+  [85] Metchnikoff, _The Prolongation of Life_, 1908, p.
+  161.
+
+
+  INDEX
+
+
+  A
+
+  Acerbi, 8
+
+  Acidity of milk, 64
+
+  Adametz on keffir, 92
+
+  Albumen, 52
+
+  Alcoholic fermentation, 17, 84
+
+  Allen & Hanbury's apparatus, 132
+
+  American incubating apparatus, 149
+
+  Analysis of milk, 48, 61
+
+  Aneyza Bedouins, 2
+
+  Arabs, 2
+
+  Arakà, 106
+
+  Ash of milk, 56
+
+
+  B
+
+  _Bacillus acidi lactici_, 107, 112
+
+  _Bacillus acidophilus_, 110, 112
+
+  _Bacillus bulgaricus_, 39, 46, 82, 108, 110, 123, 154
+
+  _Bacillus casei_, 113
+
+  _Bacillus caucasicus_, 92, 94, 95, 119
+
+  _Bacillus caucasina_, 39
+
+  _Bacillus coli_, 45
+
+  _Bacillus esterificans_, 96
+
+  _Bacillus keffir_, 96, 97
+
+  _Bacillus lebenis_, 105
+
+  _Bacillus matzoon_, 109, 110
+
+  Bacillus of long life, 46
+
+  _Bacillus putrificus_, 122
+
+  _Bacillus subtilis_, 90, 92, 107
+
+  Bacteria in milk, 76
+
+  Bacteriology of fermented milks, 84
+
+  _Bacterium acidi lactici_, 92, 96
+
+  _Bacterium aërogenes_, 92, 96
+
+  _Bacterium coli commune_, 119, 122
+
+  _Bacterium sardous_, 110, 111
+
+  Balkan Peninsula, 4
+
+  Bedouins, 2
+
+  Beijerinck on keffir, 91
+
+  Biestings, 63
+
+  Biology of the keffir grain, 90
+
+  Blood, water contents of, 50
+
+  Bourgoul, 6
+
+  Bulgarian maya, 10, 109
+
+  Bulgaricus group, cultural characteristics of, 115
+
+  Burckhardt, 6
+
+  Butin, 51
+
+  Butyric acid fermentation, 16
+
+  Butyrin, 51
+
+
+  C
+
+  Camels' milk, 2
+
+  Caprinin, 51
+
+  Capronin, 51
+
+  Caprylin, 51
+
+  Carrick on koumiss, 18
+
+  Casein, 52, 53
+
+  Centenarians in Servia, Bulgaria, and Roumania, 41
+
+  Chatterjee on Dadhi, 38
+
+  Chemistry of milk, 47
+
+  Chocolate preparations and the soured-milk bacillus, 137
+
+  Citrates in milk, 57
+
+  Clay, Paget & Company's apparatus, 132
+
+  Coagulation of casein, 59
+
+  _Colitis_, 45
+
+  Colostrum, 63
+
+  Constituents of milk, 48
+
+  Continuous apparatus for producing soured milk, 81
+
+  Creamometer, 62
+
+
+  D
+
+  Dadhi, 15, 38
+
+  Dairy Machinery & Construction Company's apparatus, 80, 82
+
+  Dairy Outfit Company's apparatus, 145
+
+  Dairy Supply Company's apparatus, 143;
+    steriliser, 148
+
+  Dirt in milk, 63
+
+  Diseases of keffir grains, 97
+
+  _Dispora caucasia_, 34, 90
+
+  Dried sour milk, 5
+
+  Duclaux, 51
+
+
+  E
+
+  Edgar's "Lactogenerator," 143
+
+  Eggs, yolk of, 52
+
+  _Enteritis_, 45
+
+  Enzymes in milk, 57
+
+  Equipment for town's dairy, 80
+
+  Essaulow on keffir, 89, 92
+
+
+  F
+
+  Fat of milk, 50
+
+  Ferments at the altar, 3
+
+  Flügge, 35
+
+  Freshfield on keffir, 33
+
+  Freudenreich, 92
+
+
+  G
+
+  Gaseous fermentation, 84
+
+  Gay-Lussac, 17
+
+  Gioddu, 107
+
+  Globulin, 54
+
+  Grieve, Dr. John, on koumiss, 19
+
+
+  H
+
+  Hammerstein on keffir, 89
+
+  Handling of milk, 68
+
+  Health and disease, 151
+
+  Hearson & Company's "Lactobator," 141
+
+  Hebrews, 3
+
+  Houran, inhabitants of, 6
+
+  Hueppe, 16
+
+  Hutchinson, Dr. H. B., bacillus from English market milk, 120
+
+  Hutchison on koumiss, 30
+
+
+  I
+
+  Ice chest, 136
+
+  Impure cultures, 158
+
+  Incubators, 141
+
+  India, 1
+
+  International Dairy Federation, 68
+
+
+  J
+
+  Jebours, 3
+
+
+  K
+
+  Kalmucks, 20
+
+  Keffir, 15, 32, 85;
+    old, 88
+
+  Keffir grain, biology of, 90
+
+  Kephir, 34, 85.
+    _See also_ Keffir.
+
+  Keshk, 6
+
+  Keshk-leben, 6
+
+  Koumiss, 15, 18;
+    Bogoyavlensky's method of preparation, 28, 98;
+    analysis, 102;
+    artificial, 102
+
+  Krannhals on keffir, 91
+
+  Kuntze, 95
+
+
+  L
+
+  Lactic acid, bacillus, 16;
+    cultures, 55;
+    fermentation, 16, 84;
+    Ferments apparatus, 131
+
+  "Lacto" apparatus, 145
+
+  "Lactobacilline," 158
+
+  _Lactobac. caucasicus_, 91
+
+  _Lactobacillus keffir_, 94
+
+  Lactometer, 64
+
+  Lapland, 8
+
+  Laurin, 51
+
+  Layard, 2
+
+  Leben, 15, 37, 104
+
+  Leben Raïb, 104
+
+  Lecithin, 52
+
+  "Le Ferment" apparatus, 128
+
+  Liebig, 17
+
+  Longevity, 155
+
+
+  M
+
+  Mares' milk, 24
+
+  Matzoon, 15, 38, 106
+
+  Maya, 42;
+    Bulgarian, 10
+
+  Maya Bulgare Company's apparatus, 131
+
+  Meeresy, 5
+
+  Metchnikoff, 34, 40, 44, 121, 158, 163
+
+  Micro-organisms, discovery of, 13
+
+  Middle Ages, 13
+
+  Milk-filling apparatus for bottles, 82
+
+  Milk, general properties of, 57;
+    of different animals, 60;
+    supply of the United Kingdom, 69;
+    industry in the United States, 71;
+    management, 74
+
+  Mitscherlich, 17
+
+  Myristin, 51
+
+
+  N
+
+  Neolithic times, 1
+
+  Nikolaiewa, 95
+
+  Nitrogenous constituents of milk, 52
+
+
+  O
+
+  Ojràn, 106
+
+  Olein, 51
+
+  Oxygala of Pliny, 4
+
+
+  P
+
+  Paleolithic times, 1
+
+  Palmitin, 51
+
+  Pasteur, 14, 78
+
+  Pasteurisation, 78
+
+  Pelouze, 17
+
+  Pilaff of rice, 5
+
+  Pina, 21
+
+  Podowyssowski on keffir, 87
+
+  Preparation, of soured milk, 81;
+    in the house, 125;
+    in the dairy, 139
+
+  Primary cooler, 78
+
+  Proteids, 53
+
+  Pyrenees, 4
+
+
+  R
+
+  Reindeer's milk as soured milk, 8
+
+  Rubruquis, William de, 19
+
+
+  S
+
+  _Saccharomyces cerevisseæ_, 90
+
+  _Saccharomyces keffir_, 32, 33, 91, 93, 94
+
+  Sakwaska, 88
+
+  Sale of Food and Drugs Act, 1899, 49
+
+  Scheele, 17
+
+  Scholl on keffir, 91
+
+  Scythians, 18
+
+  Secondary cooler, 79
+
+  Shammar Bedouins, 2
+
+  Sheneena, 2
+
+  Skolotowski on keffir, 86
+
+  Smith, Professor Robertson, 3
+
+  Soured milk, in the house, 125;
+    in the dairy, 139;
+    in health and disease, 151;
+    from impure cultures, 158;
+    use of, 159
+
+  Souring of milk, 47, 54
+
+  Specific gravity of milk, 65
+
+  Stearin, 51
+
+  Steriliser, 148
+
+  _Streptobacilli lebeni_, 39
+
+  _Streptobacillus lebenis_, 111
+
+  _Streptococcus a_, 93, 94
+
+  _Streptococcus acidi lactici_, 95, 96
+
+  _Streptococcus b_, 93, 94
+
+  _Streptococcus lacticus_, 92, 93, 122, 124
+
+  Sugar of milk, 54
+
+  Sugar preparations and the soured-milk bacillus, 137
+
+  Suter-Naef on Swiss koumiss, 26
+
+  Swedish whey cheese, 60
+
+  Swiss hard cheese, 113
+
+  Symptoms of disease, 161
+
+
+  T
+
+  Temperature allowances when testing milk, tables of, 66
+
+  Town's dairy equipment, 80
+
+  Transmission of disease by milk, 72
+
+
+  U
+
+  United Kingdom, milk supply of, 69
+
+  United States, milk industry of, 71
+
+  Urgoutnik, 43
+
+
+  V
+
+  Van Leeuwenhoek, 13
+
+  Variation limits of milk, 49
+
+  Vedas, 1
+
+  "Veronelle" apparatus, 132
+
+  Vina, 21
+
+  Vinous fermentation, 17
+
+
+  W
+
+  Willows Refrigerating Company's apparatus, 144, 145
+
+  Wilson on koumiss, 23
+
+
+  Y
+
+  Yoghourt, 9, 42, 46, 107
+
+  Yoghourt bacillus, 109
+
+
+  Z
+
+  Zakvaska, 42
+
+       *       *       *       *       *
+
+  Putnam's
+  Science Series
+
+
+  1. +The Study of Man.+ By A. C. HADDON.
+
+  2. +The Groundwork of Science.+ By ST. GEORGE MIVART.
+
+  3. +Rivers of North America.+ By ISRAEL C. RUSSELL.
+
+  4. +Earth Sculpture, or; The Origin of Land Forms.+ By JAMES GEIKIE.
+
+  5. +Volcanoes; Their Structure and Significance.+ By T. G. BONNEY.
+
+  6. +Bacteria.+ By GEORGE NEWMAN.
+
+  7. +A Book of Whales.+ By F. E. BEDDARD.
+
+  8. +Comparative Physiology of the Brain, etc.+ By JACQUES LOEB.
+
+  9. +The Stars.+ By SIMON NEWCOMB.
+
+  10. +The Basis of Social Relations.+ By DANIEL G. BRINTON.
+
+  11. +Experiments on Animals.+ By STEPHEN PAGET.
+
+  12. +Infection and Immunity.+ By GEORGE M. STERNBERG.
+
+  13. +Fatigue.+ By A. MOSSO.
+
+  14. +Earthquakes.+ By CLARENCE E. DUTTON.
+
+  15. +The Nature of Man.+ By ÉLIE METCHNIKOFF.
+
+  16. +Nervous and Mental Hygiene in Health and Disease.+ By AUGUST FOREL.
+
+  17. +The Prolongation of Life.+ By ÉLIE METCHNIKOFF.
+
+  18. +The Solar System.+ By CHARLES LANE POOR.
+
+  19. +Heredity.+ By J. ARTHUR THOMPSON, M.A.
+
+  20. +Climate.+ By ROBERT DECOURCY WARD.
+
+  21. +Age, Growth, and Death.+ By CHARLES S. MINOT.
+
+  22. +The Interpretation of Nature.+ By C. LLOYD MORGAN.
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+
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+
+  28. +The Origin of Life.+ By H. CHARLTON BASTIAN.
+
+  29. +The Bacillus of Long Life.+ By LOUDON M. DOUGLAS.
+
+  _For list of works in preparation see end of this volume_
+
+       *       *       *       *       *
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+
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+
+
+  +2.—The Groundwork of Science.+ A Study of Epistemology. By
+       ST. GEORGE MIVART, F.R.S. 8°, net $1.75.
+
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+
+
+  +3.—Rivers of North America.+ A Reading Lesson for Students of Geography
+       and Geology. By ISRAEL C. RUSSELL, Professor of Geology, University
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+
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+
+
+  +4.—Earth Sculpture; or, The Origin of Land-Forms.+ By JAMES GEIKIE,
+       LL.D., D.C.L., F.R.S., etc., Murchison Professor of Geology
+       and Mineralogy in the University of Edinburgh; author of "The
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+
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+
+
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+       Fully illustrated. 8°, net $2.00.
+
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+
+
+  +6.—Bacteria+: Especially as they are related to the economy of
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+
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+
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+  Times._
+
+
+  +8.—Comparative Physiology of the Brain and Comparative Psychology.+
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+
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+
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+
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+
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+
+
+  +12.—Infection and Immunity.+ With Special Reference to the
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+  +14.—Earthquakes.+ In the Light of the New Seismology By CLARENCE
+        E. DUTTON, Major, U. S. A. Illustrated 8°. Net, $2.00. (By
+        mail, $2.20.)
+
+  "The book summarizes the results of the men who have accomplished the
+  great things in their pursuit of seismological knowledge. It is
+  abundantly illustrated and it fills a place unique in the literature
+  of modern science"—_Chicago Tribune._
+
+
+  +15.—The Nature of Man.+ Studies in Optimistic Philosophy. By ÉLIE
+  METCHNIKOFF, Professor at the Pasteur Institute. Translation and
+  introduction by P. CHAMBERS MITCHELL, M.A., D.Sc. Oxon. Illustrated.
+  8°. Net, $1.50.
+
+  "A book to be set side by side with Huxley's Essays, whose spirit it
+  carries a step further on the long road towards its goal"—_Mail and
+  Express._
+
+
+  +16.—The Hygiene of Nerves and Mind in Health and Disease.+ By
+        AUGUST FOREL, M.D., formerly Professor of Psychiatry in the
+        University of Zurich. Authorized Translation. 8°. Net, $2.00.
+       (By mail, $2.20.)
+
+  A comprehensive and concise summary of the results of science in its
+  chosen field. Its authorship is a guarantee that the statements made
+  are authoritative as far as the statement of an individual can be so
+  regarded.
+
+
+  +17.—The Prolongation of Life.+ Optimistic Essays. By ÉLIE
+        METCHNIKOFF, Sub-Director of the Pasteur Institute. Author of
+        "The Nature of Man." etc. 8°. Illustrated. Net, $2.50.
+        (By mail, $2.70.) Popular Edition. With an introduction by
+        Prof. CHARLES S. MINOT. Net, $1.75.
+
+  In his new work Professor Metchnikoff expounds at greater length, in
+  the light of additional knowledge gained in the last few years, his
+  main thesis that human life is not only unnaturally short but
+  unnaturally burdened with physical and mental disabilities. He
+  analyzes the causes of these disharmonies and explains his reasons for
+  hoping that they may be counteracted by a rational hygiene.
+
+
+  +18.—The Solar System.+ A Study of Recent Observations. By Prof.
+        CHARLES LANE POOR, Professor of Astronomy in Columbia
+        University. 8°. Illustrated. Net, $2.00.
+
+  The subject is presented in untechnical language and without the use
+  of mathematics. Professor Poor shows by what steps the precise
+  knowledge of to day has been reached and explains the marvellous
+  results of modern methods and modern observations.
+
+
+  +19.—Climate—Considered Especially in Relation to Man.+ By ROBERT
+        DECOURCY WARD, Assistant Professor of Climatology in Harvard
+        University. 8°. Illustrated. Net, $2.00.
+
+  This volume is intended for persons who have not had special training
+  in the technicalities of climatology. Climate covers a wholly
+  different field from that included in the meteorological text-books It
+  handles broad questions of climate in a way which has not been
+  attempted in a single volume The needs of the teacher and student have
+  been kept constantly in mind.
+
+
+  +20.—Heredity.+ By J. ARTHUR THOMSON, M.A., Professor of Natural
+        History in the University of Aberdeen; Author of "The Science of
+        Life," etc. 8°. Illustrated. Net, $3.50.
+
+  The aim of this work is to expound, in a simple manner, the facts of
+  heredity and inheritance as at present known, the general conclusions
+  which have been securely established, and the more important theories
+  which have been formulated.
+
+
+  +21.—Age, Growth, and Death.+ By CHARLES S. MINOT, James Stillman
+        Professor of Comparative Anatomy in Harvard University,
+        President of the Boston Society of Natural History, and Author
+        of "Human Embryology," "A Laboratory Text-book of Embryology,"
+        etc. 8°. Illustrated.
+
+  This volume deals with some of the fundamental problems of biology,
+  and presents series of views (the results of nearly thirty years of
+  study), which the author has correlated for the first time in
+  systematic form.
+
+
+  +22.—The Interpretation of Nature.+ By C. LLOYD MORGAN, LL.D.,
+        F.R.S. Crown 8vo. Net, $1.25.
+
+  Dr Morgan seeks to prove that a belief in purpose as the causal
+  reality of which nature is an expression is not inconsistent with a
+  full and whole-hearted acceptance of the explanations of naturalism.
+
+
+  +23.—Mosquito Life.+ The Habits and Life Cycles of the Known
+        Mosquitoes   of the United States; Methods for their Control;
+        and Keys for Easy Identification of the Species in their Various
+        Stages. An account based on the investigation of the late James
+        William Dupree, Surgeon-General of Louisiana, and upon the
+        original observations by the Writer. By EVELYN GROESBEECK
+        MITCHELL, A.B., M.S. With 64 Illustrations. Crown 8vo.
+        Net, $2.00.
+
+  This volume has been designed to meet the demand of the constantly
+  increasing number of students for a work presenting in compact form
+  the essential facts so far made known by scientific investigation in
+  regard to the different phases of this, as is now conceded, important
+  and highly interesting subject. While aiming to keep within reasonable
+  bounds, that it may be used for work in the field and in the
+  laboratory, no portion of the work has been slighted, or fundamental
+  information omitted, in the endeavor to carry this plan into effect.
+
+
+  +24.—Thinking, Feeling, Doing.+ An Introduction to Mental Science.
+        By E. W. SCRIPTURE, Ph.D., M.D., Assistant Neurologist Columbia
+        University, formerly Director of the Psychological Laboratory at
+        Yale University. 189 Illustrations. 2d Edition, Revised and
+        Enlarged. Crown 8vo. Net, $1.75.
+
+  "The chapters on Time and Action, Reaction Time, Thinking Time,
+  Rhythmic Action, and Power and Will are most interesting. This book
+  should be carefully read by every one who desires to be familiar with
+  the advances made in the study of the mind, which advances, in the
+  last twenty-five years, have been quite as striking and epoch-making
+  as the strides made in the more material lines of knowledge."—_Jour.
+  Amer. Med. Ass'n._, Feb. 22, 1908.
+
+
+  +25.—The World's Gold.+ By L. DE LAUNAY, Professor at the École
+        Superieure des Mines. Translated by Orlando Cyprian Williams.
+        With an Introduction by Charles A. Conant, author of "History of
+        Modern Banks of Issue," etc. Crown 8vo. Net, $1.75.
+
+  M. de Launay is a professor of considerable repute not only in France,
+  but among scientists throughout the world. In this work he traces the
+  various uses and phases of gold; first, its geology; secondly, its
+  extraction; thirdly, its economic value.
+
+
+  +26.—The Interpretation of Radium.+ By FREDERICK SODDY, Lecturer
+        in Physical Chemistry in the University of Glasgow. Crown 8vo.
+        With Diagrams. Net, $1.75.
+
+  As the application of the present day interpretation of Radium (that
+  it is an element undergoing spontaneous disintegration) is not
+  confined to the physical sciences, but has a wide and general bearing
+  upon our whole outlook on Nature, Mr. Soddy has presented the subject
+  in non-technical language, so that the ideas involved are within reach
+  of the lay reader. No effort has been spared to get to the root of the
+  matter and to secure accuracy, so that the book should prove
+  serviceable to other fields of science and investigation, as well as
+  to the general public.
+
+
+  +27.—Criminal Man.+ According to the Classification of CESARE
+        LOMBROSO. Briefly Summarized by his Daughter, Gina Lombroso
+        Ferrero. With 36 Illustrations and a Bibliography of Lombroso's
+        Publications on the Subject. Crown 8vo. Net, $2.00.
+
+  Signora Guglielmo Ferrero's résumé of her father's work on criminal
+  anthropology is specially dedicated to all those whose office it is to
+  correct, reform, and punish the criminal, with a view to diminishing
+  the injury caused to society by his anti-social acts; also to
+  superintendents, teachers, and those engaged in rescuing orphans and
+  children of vicious habits, as a guide in checking the development of
+  evil germs and eliminating incorrigible subjects whose example is a
+  source of corruption to others.
+
+       *       *       *       *       *
+
+  The most valuable production since Darwin's "Origin of Species."
+
+  The Nature of Man
+
+  _Studies in Optimistic Philosophy_
+
+  By Élie Metchnikoff
+
+  Sub-Director of the Pasteur Institute, Paris
+
+  Translated with an Introduction by
+
+  P. Chambers Mitchell
+
+  Secretary of the Zoölogical Society
+
+  Octavo. Illustrated. Popular Edition. $1.50 net. By mail, $1.65
+
+  It is not often that a scientific book may be read with ease, profit,
+  and pleasure by the general reader, so that M. Metchnikoff's book
+  comes in the nature of an agreeable surprise. It is marked by a
+  refreshing _naïveté_ and a large simplicity which are
+  characteristically Russian. The scientific importance of this work is
+  so great that it is spoken of in England as the most valuable
+  production since Darwin's _Origin of Species_.
+
+  Opinions of the Press
+
+  "An extremely interesting and typical book.... With a distinguished
+  frankness, M. Metchnikoff defines his attitude to our universal
+  prepossessions. It is his theory that the infirmities of age are to be
+  overcome. If there be ground for this conception, humanity is to be
+  profoundly changed and what we call life now, will be the childhood
+  and youth of that longer and larger life."—H. G. WELLS, in _London
+  Speaker_.
+
+  "Undoubtedly a great book (in some quarters it has been hailed as the
+  greatest since Darwin's famous message to the world) and should be
+  read by all intelligent men and women."—_The Nation._
+
+  "A book to be set side by side with Huxley's Essays, whose spirit it
+  carries a step further on the long road towards its goal."—_Mail and
+  Express._
+
+  New York—G. P. Putnam's Sons—London
+
+       *       *       *       *       *
+
+  "_Remarkable for its simple language and clear
+  style.... Bears the stamp of a production of
+  an erudite scientist and a deep thinker._"—Science.
+
+
+  The Prolongation of Life
+
+  Optimistic Essays
+
+  _By_ Élie Metchnikoff
+
+  _Author of "The Nature of Man," etc._
+
+  _8vo. Illustrated Popular Edition. $1.75 net By mail, $1.90_
+
+  M. Élie Metchnikoff is one of those rare scientists who have found a
+  way to lay hold of and present to the world in untechnical
+  phraseology, intelligible to the lay mind, such results of his
+  researches as are of universal interest and go straight home to the
+  bosoms and business of intelligent men. _The Nature of Man_, by the
+  same author, was one of the most fascinating books, at once popular,
+  and scientific, which have appeared for decades. The book here in
+  question will stand beside it as a worthy companion volume. It is
+  satisfactory to report that, absorbed as Metchnikoff is in "material"
+  problems, and deep as he is in the mysteries of the physical universe,
+  these essays show him to be an optimist who speaks with no uncertain
+  voice.
+
+  A great deal of attention is given in _The Prolongation of Human Life_
+  to the subject of old age and its causes, with scientific observations
+  of special cases among human beings and the lower animals. The author
+  suggests means of prolonging life and health, while contemplating
+  natural death with serenity, and finding that agreeable sensations
+  accompany its approach. Beyond a certain point it seems to him a
+  disadvantage to prolong life. Passing on from these mortuary
+  lucubrations, the essays concern themselves with psychological
+  matters, with optimism and pessimism and in general with questions of
+  science and morals. The temperaments of certain great men are analyzed
+  in studies that have for their subjects respectively Byron, Leopardi,
+  Schopenhauer, and Goethe. In the preface the author says that he has
+  avoided, as far as possible, repeating points which have been
+  sufficiently treated in _The Nature of Man_.
+
+
+  G. P. PUTNAM'S SONS
+
+  NEW YORK     LONDON
+
+
+
+
+
+
+
+End of Project Gutenberg's The Bacillus of Long Life, by Loudon Douglas
+
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+The Project Gutenberg EBook of The Bacillus of Long Life, by Loudon Douglas
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: The Bacillus of Long Life
+       a manual of the preparation and souring of milk for dietary
+       purposes, together with and historical account of the use
+       of fermente
+
+Author: Loudon Douglas
+
+Release Date: March 18, 2010 [EBook #31691]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE BACILLUS OF LONG LIFE ***
+
+
+
+
+Produced by Peter Vachuska, Turgut Dincer, Chuck Greif and
+the Online Distributed Proofreading Team at
+https://www.pgdp.net
+
+
+
+
+
+
+
+  +---------------------------------------------------------+
+  | Transcriber's note:                                     |
+  |                                                         |
+  | Words in bold characters are enclosed within "+" signs. |
+  | The list of Putnam Science Series has been moved to the |
+  | advertisement section at the end of the book. The UTF-8 |
+  | version of the text file will require a Unicode capable |
+  | text reader to display a few Greek characters and "oe"  |
+  | ligatures which occur in the book.                      |
+  +---------------------------------------------------------+
+
+
+
+
+  [Illustration: THE OLDEST WOMAN IN THE WORLD AND HER SON
+
+  Baba Vasilka is 126 years old, and her son Tudor is 101.
+  They are peasants, and have lived all their lives in a
+  little village in Bulgaria. They are typical examples of
+  people who live to a great age by the use of soured milk,
+  as it has been their principal food all their lives.]
+
+
+                         The
+                Bacillus of Long Life
+
+  A Manual of the Preparation and Souring of Milk for
+    Dietary Purposes, Together with an Historical
+     Account of the Use of Fermented Milks, from
+        the Earliest Times to the Present Day,
+         and Their Wonderful Effect in the
+           Prolonging of Human Existence
+
+                         By
+             Loudon M. Douglas, F.R.S.E.
+
+               _With 62 Illustrations_
+
+
+                 G. P. Putnam's Sons
+                 New York and London
+               The Knickerbocker Press
+                        1911
+
+
+                  _Revised Edition_
+
+
+                    COPYRIGHT, 1911
+                         BY
+                  G. P. PUTNAM'S SONS
+
+
+             The Knickerbocker Press, New York
+
+
+
+
+PREFACE
+
+
+This book has been designed with a view to meet an extensive demand for
+definite data on the subject of Soured Milks. The author has had this
+matter brought before him, times without number, by those inquiring for
+authentic information on the subject, and he has therefore considered it
+desirable to gather together such information as is available in
+connection with ancient and modern practice. He has endeavoured to
+present this to the reader in concise form.
+
+The author is indebted to many friends for their assistance in getting
+the book together, and would specially mention Dr. H. B. Hutchinson,
+Bacteriologist, Rothamsted Experimental Station, for assistance in
+connection with the bacteriology of fermented milks; Mr. Thomas Douglas,
+of Wimbledon, who has assisted with the chemistry of the subject; Mr. S.
+Javrilovitch, of Belgrade, Servia, for local information and
+illustrations; Dr. Otokar Laxa, Bacteriologist, of Prague, Bohemia, for
+general assistance; the editor of _Bacteriotherapy_, New York, U.S.A.,
+for the use of the group of illustrations 30-44; the publishers of the
+_Centralblatt f�r Bakteriologie_, Jena, for the group of illustrations
+14-29; and many others, some of whom are referred to in the text.
+
+
+  CONTENTS
+
+
+  CHAPTER                                                    PAGE
+
+     I.--INTRODUCTORY--HISTORICAL                               1
+
+    II.--FERMENTED MILKS                                       15
+
+   III.--THE CHEMISTRY OF MILK                                 47
+
+    IV.--HANDLING OF MILK                                      68
+
+     V.--THE BACTERIOLOGY OF FERMENTED OR SOURED MILK          84
+
+    VI.--THE PREPARATION OF SOURED MILK IN THE HOUSE          125
+
+   VII.--THE PREPARATION OF SOURED MILK IN THE DAIRY          139
+
+  VIII.--SOURED MILK IN HEALTH AND DISEASE                    151
+
+         INDEX                                                165
+
+
+
+
+ILLUSTRATIONS
+
+
+  FIG.                                                       PAGE
+
+       THE OLDEST WOMAN IN THE WORLD AND HER SON   _Frontispiece_
+
+       THE PASS OF BUKOVA                                       2
+
+       KABYLES SOURING MILK                                     4
+
+       THE HANDLING OF MILK IN THE PYRENEES                     8
+
+       THE CONSTITUENTS OF MILK                                48
+
+   1.--MICRO-PHOTOGRAPH OF A DROP OF WHOLE MILK                58
+
+   2.--MICRO-PHOTOGRAPH OF SEPARATED MILK                      58
+
+   3.--MICRO-PHOTOGRAPH OF CREAM                               58
+
+   4.--PHOTOGRAPH OF TWO PETRI DISHES, WHICH HAVE BEEN
+         INOCULATED WITH ORDINARY MILK                         60
+
+   5.--THE CREAMOMETER                                         62
+
+   6.--TESTING-GLASS FOR EXTRANEOUS MATTER IN MILK             62
+
+   7.--LACTOMETER AND TEST-GLASS                               64
+
+   8.--PASTEURISER                                             78
+
+   9.--CONTINUOUS APPARATUS FOR THE PRODUCTION OF LARGE
+         QUANTITIES OF SOURED MILK                             82
+
+  10.--A MILK-FILLING APPARATUS                                90
+
+  11.--SECTION THROUGH A KEPHIR GRAIN                          94
+
+  12.--_Streptococcus lacticus_ (GROTENFELDT) GROWING ON
+          LACTOSE-AGAR, STAINED BY GRAM'S METHOD               96
+
+  13.--PHOTO-MICROGRAPH OF PREPARATION FROM ARMENIAN SOURED
+         MILK (MATZOON)                                       106
+
+  14.--GRANULE BACILLUS FROM YOGHOURT. SHREDDED PREPARATION
+         OF A FRESH SKIM-MILK CULTURE                         110
+
+  15.--GRANULE BACILLUS FROM YOGHOURT, CULTIVATED AFTER
+         THE USUAL AGAR METHOD                                110
+
+  16.--GRANULE BACILLUS FROM YOGHOURT. AGAR MILK SUGAR
+         CULTURE                                              110
+
+  17.--_Bacteria W._ FROM MILK, CULTIVATED TWENTY-FOUR
+          HOURS                                               110
+
+  18.--AGAR MILK SUGAR CULTURE. FROM THE ORIGINAL BULGARIAN
+         YOGHOURT                                             112
+
+  19.--AGAR MILK SUGAR CULTURE. SURFACE COLONY OF GRANULE
+         BACILLUS FROM CALF'S STOMACH                         112
+
+  20.--AGAR MILK SUGAR CULTURE. DEEP-LYING COLONY
+         OF GRANULE BACILLUS FROM CALF'S STOMACH              112
+
+  21.--AGAR MILK SUGAR. COLONY OF _Bacterium W._ FROM
+         YOGHOURT                                             112
+
+  22.--TWO COLONIES OF _Bacillus Acidophilus_ FROM CALVES'
+         MANURE                                               114
+
+  23.--BEER-WORT GELATINE                                     114
+
+  24.--SHREDDED PREPARATION OF BULGARIAN ORIGINAL YOGHOURT    114
+
+  25.--GRANULE BACILLUS FROM YOGHOURT. CULTIVATED IN SKIM
+         MILK IN TWENTY-FOUR HOURS                            114
+
+  26.--_Bacteria W._, AGAR MILK SUGAR CULTURE                 116
+
+  27.--_Bacteria acidophilus_ FROM CALVES' MANURE             116
+
+  28.--MUCUS FROM CALF'S STOMACH INOCULATED INTO MILK AFTER
+         EIGHT TRANSFERRINGS                                  116
+
+  29.--DIPLOSTREPTOCOCCUS FROM YOGHOURT. PURE CULTURE IN
+         SKIM MILK                                            116
+
+  30.--PHOTO-MICROGRAPH OF PREPARATION MADE FROM YOGHOURT,
+         SHOWING YEAST CELLS                                  118
+
+  31.--PHOTO-MICROGRAPH OF SMEAR FROM GREEK CURDLED MILK
+         CALLED "GIAOURTI"                                    118
+
+  32.--PHOTO-MICROGRAPH OF SOURED MILK INOCULATED WITH
+         A TABLET CONTAINING VIABLE AND PURE CULTURES OF
+        _Bacillus bulgaricus_                                 120
+
+  33.--PHOTO-MICROGRAPH OF MILK INOCULATED WITH A FERMENT
+         TABLE IN WHICH _Bacillus bulgaricus_ IS NO LONGER
+         VIABLE                                               120
+
+  34.--PHOTO-MICROGRAPH OF SMEAR OF CULTURE OF _Bacillus
+         bulgaricus_                                          122
+
+  35.--_Bacillus bulgaricus_, SHOWING THE CULTURES
+          IN ENGLISH COW'S MILK                               124
+
+  36.--PHOTO-MICROGRAPH OF PURE CULTURE OF _Bacillus
+         bulgaricus_                                          124
+
+  37.--PHOTO-MICROGRAPH OF SMEAR OF COMBINED CULTURE
+         OF _Bacillus bulgaricus_ AND _Bacteria
+         paralacticus_                                        124
+
+  38.--PHOTO-MICROGRAPH OF SMEAR OF ONE-MONTH CULTURE
+         OF _Bacillus bulgaricus_                             126
+
+  39.--PHOTO-MICROGRAPH OF CULTURE OF _Bacillus bulgaricus_
+         IN MALT                                              126
+
+  40.--PHOTO-MICROGRAPH OF SMEAR FROM MILK THAT HAD BEEN
+         ALLOWED TO SOUR SPONTANEOUSLY                        126
+
+  41.--PHOTOGRAPH OF AGAR CULTURE, INOCULATED WITH A LACTIC
+         POWDER                                               128
+
+  42.--PHOTOGRAPH OF TEST-TUBES OF STERILE MILK, INOCULATED
+         WITH A TABLET PREPARATION SAID TO CONTAIN PURE
+         CULTURES                                             128
+
+  43.--PHOTOGRAPH OF TEST-TUBES OF STERILE MILK, EACH TUBE
+         HAVING BEEN INOCULATED WITH A TABLET OF A
+         PREPARATION SAID TO CONTAIN PURE CULTURES            128
+
+  44.--PHOTOGRAPH OF TEST-TUBES OF STERILE MILK INOCULATED
+         WITH A TABLET OF "LACTOBACILLINE"                    130
+
+  45.--APPARATUS OF "LE FERMENT" CO.                          129
+
+  46.--SOURED MILK APPARATUS OF THE MAYA BULGARE COMPANY,
+         LIMITED                                              130
+
+  47.--LACTIC FERMENTS, LIMITED, APPARATUS                    131
+
+  48.--MESSRS. ALLEN & HANBURY'S SOURED MILK APPARATUS        132
+
+  49.--VIRONELLE APPARATUS FOR SOURING MILK, MADE BY
+         MESSRS. CLAY, PAGET & COMPANY, LIMITED               132
+
+  50.--"LACTOBATOR" MADE BY MESSRS. CHARLES HEARSON & CO.,
+          LIMITED                                             140
+
+  51.--MESSRS. HEARSON & COMPANY'S "LACTOBATOR"               142
+
+  52.--EDGAR'S "LACTOGENERATOR," SOLD BY THE DAIRY SUPPLY
+         CO., LIMITED                                         143
+
+  53.--APPARATUS OF THE WILLOWS REFRIGERATING CO., LIMITED    144
+
+  54.--"LACTO" APPARATUS OF THE DAIRY OUTFIT CO., LIMITED     145
+
+  55.--STERILISING APPARATUS FOR STERILISING MILK ON
+         THE LARGE SCALE                                      146
+
+  56.--ANOTHER METHOD OF STERILISING (DAIRY SUPPLY
+         CO., LTD.). AN AMERICAN APPARATUS FOR PREPARING
+         SOURED MILK                                          148
+
+  57.--AN AMERICAN APPARATUS FOR PREPARING SOURED MILK        149
+
+
+
+
+THE BACILLUS OF LONG LIFE
+
+
+
+
+CHAPTER I
+
+INTRODUCTORY--HISTORICAL
+
+
+The milk industry is one of the oldest known to mankind, and it is
+difficult to imagine a time when milk in one way or another did not form
+a part of the diet of the human race. There is a good deal of evidence
+to show that in Paleolithic and Neolithic times, cattle were part of the
+possessions of the nomadic races; and, according to the Vedas, the
+manufacture of butter was known in India 1500 years B.C.
+
+In the eastern part of Europe, milk has always been looked upon as one
+of the principal kinds of food, but not necessarily the milk of cows,
+as, from ancient times to the present day, the milk from camels,
+buffaloes, sheep, and goats has been used indiscriminately throughout
+the East.
+
+According to Layard,[1] "the Bedouins do not make cheese. The milk of
+their sheep and goats is shaken into butter or turned into curds; it is
+rarely or never drunk fresh, new milk being thought very unwholesome, as
+soon by experience I found it to be, in the desert. I have frequently
+had occasion to describe the process of making butter by shaking the
+milk in skins. This is also an employment confined to women, and one of
+a very laborious nature. The curds are formed by boiling the milk, and
+then putting some curds made on the previous day into it and allowing it
+to stand. When the sheep no longer give milk, some curds are dried, to
+be used as a leaven on a future occasion. This preparation, called
+_leben_, is thick and acid, but very agreeable and grateful to the taste
+in a hot climate. The sour milk, or _sheneena_, a universal beverage
+amongst the Arabs, is either buttermilk pure and diluted, or curds mixed
+with water.
+
+  [Illustration: THE PASS OF BUKOVA.--During the revolution
+  of 1904, a number of Turkish soldiers, just before
+  traversing this pass, were given coffee containing "caf�"
+  by a Bulgarian coffee-seller, or keeper of a small khan.
+  Whilst in the pass the poison began to take effect, and
+  they realized that they had been poisoned. Fortunately for
+  them, a peasant with three horses loaded with Yoghourt
+  (soured milk) had taken advantage of their escort. The
+  soldiers ate freely of the Yoghourt, which counteracted
+  the effects of the poison.]
+
+"The camel's milk is drunk fresh. It is pleasant to the taste, rich, and
+exceedingly nourishing. It is given in large quantities to the horses.
+The Shammar and Aneyza Bedouins have no cows or oxen, those animals
+being looked upon as the peculiar property of tribes who have forgotten
+their independence, and degraded themselves by the cultivation of land.
+The sheep are milked at dawn, or even before daybreak, and again in the
+evening on their return from the pastures. The milk is immediately
+turned into leben, or boiled to be shaken into butter. Amongst the
+Bedouins and Jebours it is considered derogatory to the character of a
+man to milk a cow or sheep, but not to milk the camel. The Sheikhs
+occasionally obtain dates from the cities. They are eaten dry with bread
+and leben, or fried in butter, a very favourite dish of the Bedouin...."
+
+The practice is now the same as it was in scriptural times, when milk
+was looked upon as the principal article of diet, and throughout the
+Scriptures there are copious references to milk in different forms, some
+of which are of peculiar interest at the present day.
+
+It may be noticed, for example, that milk is absent from the sacred
+offerings amongst the Hebrews, and this was ascribed by the late
+Professor Robertson Smith to the fact that all ferments were excluded
+from presentation at the altar,[2] it being recognised that, owing to
+the hot climate, milk of all kinds became rapidly sour, and in this way
+came to be looked upon as only fit for consumption when in that
+condition. It has been suggested that the prohibition referred to is on
+the same level as the prohibition of the use of blood, "as milk has
+sometimes been regarded as a kind of equivalent for blood, and
+containing the sacred life."[3] To this day the wandering tribes of
+Arabia consider the milk of their camels and flocks more refreshing when
+it has been slightly fermented or soured by being poured into a
+milk-skin on the inside of which are still sticking sour clots from the
+previous milking, and there shaken for a brief period; but this slightly
+soured milk (the _Oxygala_ of Pliny) is known widely in the East simply
+as leben (milk). The name is also applied to what we term buttermilk.[4]
+
+  [Illustration: KABYLES SOURING MILK
+
+  In the north of Africa the use of soured milk is common,
+  and the illustration shows Kabyles shaking a skin full of
+  milk so as to sour it. The skin has previously been used
+  for the same operation, and, as a consequence, clots of
+  milk are left from the previous day's use, and thus
+  fermentation is set up.]
+
+The use of milk-skins for the carrying of milk is not confined to one
+country, as, while it is common all over the north of Africa, it is also
+known in the Pyrenees and in some parts of the Balkan Peninsula, the
+object being identical in each case; and when it is intended to make
+butter from the milk, the skin is simply rocked between the knees until
+the butter separates, a process of butter-making which was also used
+after the introduction of earthenware churns.[5] Dried soured milk is
+also used by the Arabs, and it is reconstituted when required by rubbing
+it up with a little water, and it is known as _Meeresy_.[6] The ordinary
+soured milk is the common article of diet, and is looked upon as being
+necessary at every meal, and travellers frequently refer to the use of
+this product, as a few references will show.
+
+Charles G. Addison states: "A supper was brought in on a round tray. In
+the centre was a huge pilaff of rice, and around it several small dishes
+of stewed meats, grilled bones, sour clotted milk called _yaoort_,[7]
+bits of meat roasted, etc....
+
+"We retired into a tent to breakfast, where we found an immense bowl of
+delicious fresh camels' milk, with thin hot cakes of unleavened bread,
+baked upon the ashes, ready prepared for us. The principal food of the
+Bedouins consists of flour and some camels' milk made into a paste,
+boiled, and eaten swimming in melted grease and butter; boiled wheat
+and beans dried in the sun and prepared with butter are a favourite
+dish. They are all remarkably fond of butter and grease; the butter is
+made in a goat-skin, suspended to the tent pole, and constantly shaken
+about by the women."[8]
+
+Burckhardt[9] says: "The provisions of my companion consisted only of
+flour; besides flour, I carried some butter and dried leben (sour milk),
+which would dissolve in water. It forms not only a refreshing beverage,
+but is much to be recommended as a preservative of health when
+travelling in summer. These are our only provisions." With regard to the
+inhabitants of the Houran, Burckhardt relates that the most common
+dishes of these people are _bourgoul_ and _keshk_. "In summer they
+supply the place of the latter by milk, leben, and fresh butter. Of the
+bourgoul I have spoken on other occasions; there are two kinds of
+keshk--_keshk-hammer_ and _keshk-leben_. The first is prepared by
+putting leaven into the bourgoul and pouring water over it. It is then
+left until almost putrid, and afterwards spread out in the sun and
+dried, after which it is pounded, and, when called for, served up mixed
+with oil or butter. The keshk-leben is prepared by putting leben into
+the bourgoul instead of leaven; in other respects the process is the
+same. Keshk and bread are the common breakfasts. Towards sunset a plate
+of bourgoul, or some Arab dish, forms the dinner."
+
+Again, Taylor[10] says: "I received a small jug of thick buttermilk, not
+remarkably clean, but very refreshing."
+
+These references particularly refer to the East, from which it would
+appear that soured milk was universally known in ancient times as it is
+at the present day, and this remark applies not only to Egypt,
+Palestine, and Arabia, but throughout Turkey and the Balkan States,
+where the consumption of soured milk is equally common. It seems curious
+that the use of this commodity should have been confined for centuries
+to the East, as we shall see later on that its dietetic value is so
+great that it is really a wonderful thing that no one has taken the
+trouble to introduce its use to the Western nations until quite
+recently.
+
+  [Illustration: THE HANDLING OF MILK IN THE PYRENEES
+
+  The handling of milk in the Pyrenees is, more especially
+  in the villages, conducted in goat or sheep skins, in a
+  similar way to the methods which prevail in Eastern
+  Europe, and the picture shows a skin of milk on a small
+  farm in the Pyrenees. The churning is very often performed
+  by simply rocking the skin between the knees, acidity
+  being induced by remnants of the previous day's milk;
+  souring of milk is induced by the same method.]
+
+A curious example of how the virtues of such an article may be
+independently discovered by another nation is to be found in Lapland,
+where reindeer's milk is the article used. "The reindeer's milk," says
+Acerbi,[11] "constitutes a principal part of the Laplander's food, and
+he has two methods of preparing it, according to the season. In summer
+he boils the milk with sorrel till it arrives to a consistence; in this
+manner he preserves it for use during that short season. In winter the
+following is his method of preparation: The milk, which he collects in
+autumn till the beginning of November, from the reindeer, is put into
+casks, or whatever vessels he has, in which it soon turns sour, and, as
+the cold weather comes on, freezes, and in this state it is kept. The
+milk collected after this time is mixed with cranberries and put into
+the paunch of the reindeer, well cleaned from filth; thus the milk soon
+congeals, and it is cut out in slices, together with the paunch, to
+effect which a hatchet is used, for no smaller instrument would perform
+the office of dividing that lump of ice. It is then separated into small
+pieces and eaten throughout the winter every day at noon, which is the
+Laplander's dinner-hour. It must be presumed, as it is served up without
+being brought to the fire, that this is ice-cream in the greatest
+perfection: here are flesh and fruit blended with the richest
+butyraceous milk that can be drawn from any animal; but, notwithstanding
+the extraordinary fatness, which may be supposed to resist in a great
+degree the effect of cold, this preparation, as our good missionary
+remarks with a degree of feeling, as if his teeth still chattered whilst
+he delivered the account, chills and freezes the mouth in a violent
+manner whenever it is taken. The milk which is drawn late in the winter
+freezes immediately after being drawn. This is put into small vessels
+made of birchwood, and is considered by the Laplander as such an
+extraordinary delicacy, that he reserves it as the most acceptable
+present he can offer even a missionary. It is placed before the fire and
+eaten with a spoon as it is thawed. When put by, it is carefully covered
+up, because if the cold air gets to it afterwards, it turns of a yellow
+colour and becomes rancid."
+
+Amongst the peasants at the present day, soured milk is known as
+_yoghourt_, a word which is spelt differently according to the locality
+in which it is used. The method of preparation is practically the same
+everywhere, and a short description of the process as now carried out
+in one place would, with slight modifications, apply to the general
+method adopted all over the East.
+
+"The culture," says a correspondent at Varna, "which is used for the
+preparation of yogourt, is known as 'Maya' or as 'Bulgarian Maya.' The
+milk which is to be converted into yogourt must first be freed from all
+bacteria by boiling and allowed to cool to the temperature of 45� C.; it
+is then inoculated with maya and maintained at an even temperature of
+45� C. during several hours. There are two kinds of maya, or ferment,
+one known as sour, and the other as sweet maya.
+
+"In Europe small stoves, made expressly for the purpose, are used to
+maintain the milk at the proper temperature. In this country, however,
+after the milk has been boiled, it is merely poured into a bowl and
+allowed to cool to approximately 45� C., then a tablespoonful of this
+tepid milk is well mixed (in a small bowl apart) with a similar quantity
+of maya, and the mixture, when it has become quite homogeneous, is added
+to the bowl of tepid milk and stirred slightly. (One tablespoonful of
+maya is sufficient to ferment one litre of milk.) A cover is then placed
+on the bowl and the whole is enveloped in flannel and left in a warm
+place for three hours in summer, and somewhat longer in winter.
+
+"The process of preparation is complete when the mixture assumes the
+appearance of a soft mass somewhat resembling cream cheese, but less
+solid. The flannel is then removed, the bowl uncovered and placed in a
+cool spot until needed for consumption. Of the yogourt thus prepared, a
+tablespoonful is kept to serve as maya for the following day.
+
+"The best yogourt is prepared from sheep's milk, the second quality from
+buffaloes' milk, and the third quality from cows' milk. Yogourt forms an
+almost daily article of diet with the natives in this country."[12]
+
+With regard to the time stated for the fermenting process, it must be
+noted that since the subject has been investigated so thoroughly, the
+time required for fermentation has been found to be nearer ten than
+three hours, but this will be dealt with in a subsequent chapter.
+
+Historically it may be gleaned from the fragmentary references which we
+have given, that soured milk has, from time immemorial, formed the
+principal article of diet of a great many peoples, and the notable
+feature in connection with it is, that in some countries where it is in
+daily use, the age limit for human beings seems to be very much
+extended, and it would appear that there is a direct connection between
+the use of soured milk and longevity. In Bulgaria, for example, it is
+stated that the majority of the natives live to an age considerably in
+excess of what is recognised as the term of life amongst Western
+nations, and inquiry has shown that in the eastern part of Southern
+Europe, amongst a population of about three millions, there were more
+than three thousand centenarians found performing duties which would not
+be assigned to a man of sixty-five years of age elsewhere. It is quite
+common to find amongst the peasants who live to such a large extent upon
+soured milk, individuals of 110 and 120 years of age.[13]
+
+In the ancient dairy practice, as we have seen, soured milk was the
+principal product, and the extraordinary ages which are recorded of the
+patriarchs, if translated into the modern denomination, would not appear
+to be so imaginary after all, when it is considered that we have
+thousands of examples at the present day of men and women enjoying quite
+as long a term of existence. It has been noticed also, that while these
+very old people are able to perform a certain amount of manual labour,
+there is not the same tendency to the mental decay which is so prominent
+and sad a feature amongst Western nations, at a period of about seventy
+or eighty years of age. It would seem, indeed, as if the habit of living
+long was well known in ancient times, and that, like many other of the
+valuable arts and sciences, it fell under a cloud during the Middle
+Ages, or, perhaps, the significance of the use of soured milk fell into
+neglect, and, even after the revival of letters in the sixteenth
+century, still remained obscure.
+
+The discovery of micro-organisms in perishable products, which is
+attributable to Anthony Van Leeuwenhoek, a Dutchman, whose vocation was
+the polishing of lenses, and who lived between 1632 and 1723, altered
+our point of view, not only of disease, but of all the functions carried
+on by the lower organisms. Since Van Leeuwenhoek's time, the germ theory
+has grown to vast proportions and has more especially been applied with
+splendid results to the study of milk. As we shall see later, the
+researches of modern investigators have led them to the conclusion that
+micro-organisms play such an important part in the milk supply, that it
+is impossible to carry it on safely without a knowledge of the
+bacteriology of the subject. This view began to prevail about 1890, some
+twenty years after Pasteur had shown what fermentation really meant.
+Since that time, the progress in dairying has been continuous, and,
+during recent years, attention has been directed to soured milk to such
+an extent that it has become necessary for all who are interested in the
+handling of milk and milk products to have a knowledge of the subject,
+as it seems clearly demonstrated that, under proper direction, there is
+every possibility of its forming an important element in the
+prolongation of life.
+
+
+
+
+CHAPTER II
+
+FERMENTED MILKS
+
+
+There is considerable variety in the number of soured or fermented
+milks, and they are known by various names, such as Koumiss or Koomiss,
+which is prepared from mares' milk; Keffir, which was originally
+discovered in the mountains of the Caucasus, and which is prepared with
+Keffir grains; Leben, an Egyptian product prepared from the milk of the
+buffalo, cow, or goat; Matzoon, a soured milk which is prepared in
+Armenia from ordinary cows' milk; Dadhi, an Indian preparation from
+cows' milk. All of these owe their special characteristics to the fact
+of their having undergone lactic and alcoholic fermentation.
+
+"Milk left to itself," says Blyth,[14] "at all temperatures above 90� F.
+begins to evolve carbon dioxide, and this is simply a sign and result of
+fermentation. If this fermentation is arrested or prevented, the fluid
+remains perfectly sweet and good for an indefinite time. Besides the
+production of carbon dioxide during decomposition, a certain portion of
+milk sugar is converted into lactic acid, some of the casein and albumen
+are broken up into simpler constituents, and a small proportion of
+alcohol produced, which by oxidation appears as acetic acid, while the
+fat is in part separated into free fatty acids, which ultimately unite
+with the ammonia produced by the breaking up of the albuminoids. The
+main fermentation of milk is a special kind which of late years has been
+much studied, and is known as _lactic fermentation_. Accompanying lactic
+fermentation there is nearly always a weak butyric and a weak alcoholic
+fermentation."
+
+One of the organisms causing _Butyric Acid Fermentation_ is a bacillus 3
+to 10� in length, and about 1� in breadth. It has power of movement, and
+when cultivated in gelatine, liquefies the gelatine, forming a scum on
+the surface. When the bacillus is sown into sterile milk, the following,
+according to Hueppe, are the changes:
+
+"If the milk thus infected is incubated, on the second day a clear,
+slightly yellow fluid is seen under the layer of cream; this fluid
+increases from day to day, so that gradually a column of fluid is
+formed which is quite clear above, but below is turbid; the casein, at
+first thrown down in a firm coagulum, in the course of eight days begins
+to be attacked, and by the end of two or three weeks most of it is
+dissolved. The filtered fluid gives the biuret reaction; it contains
+leucin, tyrosin, and ammonia; hence it is clear that the ferment acts to
+some extent as a digestive of albumen. In advanced butyric acid
+fermentation, the fluid is most offensive, and may have an alkaline
+reaction."
+
+Lactic acid was first isolated by Scheele in 1780 from soured milk, but
+its exact constitution was not determined until later by Liebig,
+Mitscherlich, Gay-Lussac, and Pelouze: "It is widely distributed in
+nature, occurring in the sap of the vine and in most fermented liquids,
+especially in soured milk; it is not, however, present in fresh
+milk."[15]
+
+In all the Eastern preparations referred to, the lactic fermentation is
+produced, followed by alcoholic fermentation, which is due to the slow
+decomposition of the milk sugar, the vinous fermentation being most
+readily set up in milks which contain a larger relative proportion of
+milk sugar and water, such as the milk derived from the mare, the sheep,
+and the camel. As these fermented milks have different characteristics,
+it is necessary to the thorough understanding of the process of
+manufacture at the present day, to examine them in some detail.
+
+_Koumiss._--The greatest of all the fermented milks is koumiss, and it
+has been celebrated from the most ancient times until the present day,
+as being the principal food of the wandering tribes of Khirgiz,
+Bashkirs, Kalmucks, and Tartars, who inhabit the steppes of European
+Russia and the plains of South, Western, and Central Asia. According to
+Carrick, who has written an interesting volume on the subject,[16] the
+nomads who inhabit these vast territories are shut up under the most
+miserable circumstances during the winter time and at the advent of
+spring they roam over the steppes from morning to night, usually in the
+saddle. The milk yielded at such time by the mares is carefully
+collected, and these nomads consume enormous quantities of it in the
+fermented state, this habit having been in existence amongst them from
+time immemorial. It is said that the Scythians, long before the
+Christian era, used fermented mares' milk; and there are ornaments in
+existence in Russia, of Scythian origin, which exhibit in detail the
+preparation of koumiss from mares' milk. In historical times, the first
+mention of koumiss was in the twelfth century, when it is referred to in
+the Ipatof Chronicles. During the thirteenth century William de
+Rubruquis, a French missionary, wrote about his travels in Tartary, and
+he described how he had first become acquainted with koumiss, and how he
+found it savoury to the palate. Subsequent to this, however, there is
+very little mention of koumiss in Russian history, or, for that matter,
+in any other, and the first really scientific contribution on the
+subject was by Dr. John Grieve, who was a surgeon in the Russian army,
+and who in the year 1784 sent a description of koumiss to the Royal
+Society of Edinburgh,[17] of which he was a member, and the title of it
+was, "An Account of the Method of Making Wine called by the Tartars
+Koumiss, with Observations on its Use as a Medicine." Dr. Grieve
+strongly advocated the use of koumiss as beneficial in cases of wasting
+diseases, and subsequently it was adopted by the medical profession,
+with the result that sanatoria for the treatment of pulmonary
+consumption were established at Samara and other places in Russia, and
+met with very great success; and at the present day such sanatoria are
+carried on, but the bacteriology of the subject now being thoroughly
+understood, the methods of preparation have been somewhat modified.
+
+An interesting account of koumiss is given by Clarke,[18] who says:
+
+"Everybody has heard of koumiss, and the brandy which the Kalmucks are
+said to distil from the milk of mares. The manner of preparing these
+liquids has been differently related, and perhaps is not always the
+same. They assured us that the brandy was merely distilled from
+buttermilk. The milk which they collect overnight is churned in the
+morning into butter; and the buttermilk is distilled over a fire made
+with the dung of their cattle, particularly the dromedary, which makes a
+steady and clear fire like peat. But other accounts have been given both
+of the koumiss and the brandy. It has been usual to confound them, and
+to consider the koumiss as their appellation for the brandy so obtained.
+By other information I could gain, not only here, but in many other
+camps which we afterwards visited, they are different modifications of
+the same thing although different liquors; the koumiss being a kind of
+sour milk, like that so much used by the Laplanders called _pina_, and
+which has undergone, in a certain degree, the vinous fermentation; and
+the brandy an ardent spirit obtained from koumiss by distillation. In
+making koumiss they sometimes employ the milk of cows, but never if
+mares' milk can be had, as the koumiss from the latter yields three
+times as much brandy as that made from cows' milk.
+
+"The manner of preparing the koumiss is, by combining one sixth part of
+warm water with any given quantity of warm mares' milk. To these they
+add, as a leaven, a little old koumiss, and agitate the mass till
+fermentation ensues. To produce the vinous fermentation, artificial heat
+and more agitation is sometimes necessary. This affords what is called
+koumiss. The subsequent process of distillation afterwards obtains an
+ardent spirit from the koumiss. They call it _vina_. In their own
+language it bears the very remarkable appellation of _rack_ and _racky_,
+doubtless nearly allied to the names of our East India spirit _rack_
+and _arrack_. We brought away a quart bottle of it, and considered it
+very weak bad brandy, not unlike the common spirit distilled by the
+Swedes and other northern nations. Some of their women were busy making
+it in an adjoining tent. The simplicity of the operation and their
+machinery was very characteristic of the antiquity of this chemical
+process. Their still was constructed of mud, or very coarse clay; and
+for the neck of the retort they employed a cane. The receiver of the
+still was entirely covered by a coating of wet clay. The brandy had
+already passed over. The woman who had the management of the distillery,
+wishing to give us a taste of the spirit, thrust a stick, with a small
+tuft of camel's hair at its end, through the external covering of clay,
+and thus collecting a small quantity of the brandy, she drew out the
+stick, dropped a portion on the retort, and, waving the instrument above
+her head, scattered the remaining liquor in the air. I asked the meaning
+of this ceremony, and was answered that it is a religious custom to give
+always the first drop of the brandy which they draw from the receiver to
+their God. The stick having been plunged into the receiver again, she
+squeezed it into the palm of her dirty and greasy hand, and after
+tasting the liquor, presented it to our lips."
+
+Another interesting account of the preparation of koumiss is given by
+John M. Wilson in the _Rural Encyclop�dia_,[19] and it shows that the
+methods in use about the middle of last century did not differ
+materially from those which existed centuries before.
+
+Wilson says: "Khoumese is vinously fermented mares' milk. Any quantity
+of fresh mares' milk is put into wooden vessels; a sixth part of water
+just off the boil is mixed with it; an eighth part of old khoumese or of
+the sourest possible cows' milk is added; the mixture is kept from
+fifteen to twenty-four hours, covered up with several folds of coarse
+linen cloth and with a very thick board, and without being stirred or in
+any degree disturbed, in a moderately warm place till it becomes
+thoroughly sour, and sends up a thick mass to its surface; it is then
+beaten and pounded and stirred till the curd is not only broken, but so
+thoroughly mixed with the serum as to form a thick liquid; it next
+remains covered and at rest during twenty-four hours more, and it is
+finally put into a common butter churn and beaten and blended into a
+state of perfect homogeneity. It is now fit for use; yet it acquires an
+increase of given properties if it be allowed to stand for a few days,
+and either then or now it would, if distilled, yield nearly one third of
+its own bulk of a weak spirit which will bear to be rectified. Whenever
+it is used it must be previously so agitated that its component parts
+may be well mixed together, and it may be kept either in pans for
+immediate use or in casks for more remote use; and if placed in a cool
+cellar it will remain good during three or four months."
+
+Mares' milk owes its peculiar fitness for making koumiss to its
+containing a large proportion of sugar of milk, and readily undergoing
+the vinous fermentation, and it possesses a general medicinal reputation
+among the Tartars similar to that which asses' milk has partially
+acquired in Britain. "That mares' milk will undergo vinous fermentation
+and yield a certain quantity of spirit," says a writer in the _Magazine
+of Domestic Economy_, "is not generally known, and it was reserved for a
+nation of demi-savages to render this circumstance available as an agent
+of health, as well as an agreeable and nourishing beverage. Every
+educated person, however, has heard that the Tartars drink mares' milk,
+though few know that this milk is taken on account of its specific
+virtues alone, and not as a substitute for cows' milk, of which they
+have abundance, and with which they adulterate mares' milk when scarce."
+But the koumiss is reputed to be much more medicinal than the mares'
+milk itself; and on account of its being free from all tendency to
+curdle in the stomach, and of its possessing most of the nutritive power
+of the milk in combination with native fermented spirit, it has been
+strongly recommended by some persons as a remedy for most or all cases
+of general debility, of nervous languor, and even pulmonary disease.
+
+"Khoumese is called sometimes _koumiss_ and sometimes milk wine."
+
+From these references it will be seen that koumiss is an alcoholic drink
+made by the fermentation of mares' milk, but it is also frequently
+prepared from the milk of the camel and cows' milk. It is stated that a
+similar preparation to Russian koumiss is made in Switzerland from cows'
+milk simply by the addition of a little sugar and yeast to skim milk;
+"it contains more sugar and less lactic acid than Russian koumiss, and
+on account of the much greater proportion of casein contained in cows'
+milk, differs considerably from that prepared from mares' milk."
+Suter-Naef gives the composition of a Swiss koumiss[20] manufactured at
+Davos as follows:
+
+                      In Grams.             Per Litre
+                      Per cent.            (by weight).
+  Water                90.346               1019.64 grams.
+  Alcohol               3.210                 36.23   "
+  Lactic acid           0.190                  2.14   "
+  Sugar                 2.105                 23.75   "
+  Albuminates           1.860                 20.99   "
+  Butter                1.780                 20.09   "
+  Inorganic salts       0.509                  5.74   "
+  Free carbonic acid    0.177                  2.00   "
+
+The ferments used in the preparation of koumiss are stated by Carrick to
+be of two different kinds, artificial and natural.
+
+"Of the natural ferments two have been resorted to. One is mentioned by
+Grieve, which he borrowed from the Bashkirs of Orenbourg, and which
+simply consists in the addition of one sixth part of water and one
+eighth of the sourest cows' milk to fresh mares' milk; the other has
+been employed, and was, if I mistake not, first recommended by
+Bogoyavlensky. It is a very simple if rather a tedious method. New
+mares' milk, diluted with one third its bulk of water, is placed in the
+_saba_,[21] and while allowed to sour spontaneously, is continually
+beaten up. This milk gradually undergoes the vinous fermentation, and in
+twenty-four hours is converted into weak koumiss. The disadvantage of
+this mode of commencing fermentation is obvious--viz., the great waste
+of time in agitation. Hence it is only employed when no artificial
+ferment is obtainable.
+
+"In starting the process of fermentation in mares' or any other kind of
+milk, therefore, an artificial ferment is more frequently employed than
+a natural one. The former is used only for converting the first portion
+of milk into koumiss; the latter is always resorted to afterwards.
+
+"Of artificial ferments the variety is great, for besides all putrefying
+animal matters which contain nitrogen--such as blood, white of egg,
+glue, and flesh--certain mineral substances which act by souring the
+milk are also capable of exciting fermentation.
+
+"Now, many of the nomads, whose mares either give no milk or are not
+milked in winter, commence the preparation of their koumiss in spring by
+borrowing a ferment from the animal, mineral, or vegetable kingdom. Thus
+a mixture of honey and flour is the favourite ferment with some races of
+nomads; a piece of fresh horse-skin or tendon is preferred by others,
+while a few resort to old copper coins, covered with verdigris, for
+starting fermentation. In the choice of a ferment they are guided solely
+by habit and tradition. As it would be useless, almost impossible, to
+give a list of all the foreign substances that have been employed with
+the view of converting mares' milk into koumiss, it will be best to
+consider the simplest artificial ferments, and those most generally in
+use.
+
+"The simplest way is that recommended by Bogoyavlensky, and adopted and
+modified by Tchembulatof.[22] It is prepared thus: 'Take a quarter of a
+pound of millet-flour, add water to it, and boil it down to the
+consistence of thick oatmeal porridge. Then heat separately, in another
+vessel, eleven pints of milk to boiling-point, and allow it to cool
+down. When its temperature has fallen to 95� F., pour it into a wooden
+bowl or tub, and add the boiled flour to it. The upper and open part of
+the vessel is then covered with a piece of coarse linen, and left at
+rest--at a temperature of about 99� F.--from twenty-four to forty-eight
+hours. The appearance of small bubbles, which keep bursting on the
+surface of this liquid, combined with a vinous or acid odour, prove that
+the ferment is ready. To this fermenting fluid twenty-two quarts of new
+milk are gradually (_i.e._, every ten minutes) added, and the whole mass
+is continuously beaten up for twelve hours. The temperature during
+stirring should never be higher than 94� F. The whole fluid soon begins
+to ferment, and after twelve hours a not unpleasant koumiss is ready.
+This should be filtered through a horse-hair or muslin sieve, after
+which it is fit for drinking. This liquid is called weak koumiss; but a
+limited portion of the lactine has undergone the lactuous and vinous
+fermentations, and thus the percentage of alcohol is small. Koumiss at
+an ordinary temperature remains weak for twelve hours after it has been
+beaten up, and then gradually passes into medium.'"
+
+Curiously enough, the richness of cows' milk in fat militates against
+its being a good raw material for the making of koumiss, owing to the
+production of small quantities of butyric acid, which follows upon the
+fermentation, so that it is desirable, if koumiss is to be prepared from
+cows' milk, that the fat should be first of all eliminated, so that the
+separated milk will then approximate to the composition of mares' milk.
+
+"The chemical changes," says Hutchison,[23] "which take place in the
+milk under the double fermentation are not difficult to follow; the
+lactic ferment simply changes part of the sugar into lactic acid, the
+vinous ferment eats up a very small part of the proteid of the milk,
+and, at the same time, produces from the sugar a little alcohol and a
+good deal of carbon dioxide; the milk thus becomes sour, it effervesces
+and is weakly alcoholic, but the lactic acid causes the casein to be
+precipitated just as it does in the ordinary souring of milk, and the
+casein falls down in flocculi."
+
+As will have been noticed, it is an essential part of the process of
+koumiss-making to keep the milk in a state of agitation during the
+period of fermentation, a process which is intended to permit of oxygen
+being taken up by the fermenting fluid, while, at the same time, the
+casein is broken up into a state of fine division. The casein also, or
+at least a portion of it, becomes very soluble, and after twelve hours
+of fermentation the taste of the product is only slightly sour, and the
+milk taste still remains. This taste, however, disappears in
+twenty-four hours, owing to the rapid development of the lactic acid
+organisms. After this lapse of time the sugar is entirely destroyed, and
+the strong koumiss which results is a thin sour fluid which effervesces
+briskly, and in this condition will keep for an indefinite period. "The
+net change which has taken place in the original milk may be summed up
+by saying that the sugar of the milk has been replaced by lactic acid,
+alcohol, and carbon dioxide, the casein has been partly precipitated in
+a state of very fine division, and partly pre-digested and dissolved,
+while the fat and salts have been left much as they were."[24]
+
+Violent stirring or agitation of the cultures does not seem to work so
+much by supplying oxygen to the fermenting liquid, as by ensuring a
+thorough distribution of the micro-organisms throughout the liquid, and
+thus dividing the casein.
+
+The greater number of the organisms are facultative an�robes and oxygen
+is not necessary. Again, koumiss put up in bottles on the first day is
+regularly shaken although air is excluded.
+
+_Keffir._--Keffir is a kind of fermented milk which has been in use in
+the Caucasus for quite a long time, as koumiss has been in the steppes.
+It differs from koumiss, however, in this respect, that it is prepared
+from either sheep's, goats', or cows' milk. The process is started by
+the addition of keffir grains to the milk, which is contained in
+leathern bottles. These keffir grains are small solid kernels which are
+kept in families and handed on from one generation to another.[25] The
+grains are the origin of the ferment, as they disseminate in the milk
+micro-organisms of a lactic yeast (_Saccharomyces kefir_ Beyerinck and
+Freudenreich) and also the bacillus _Bacterium caucasicum_, which
+develop rapidly and split up the milk sugar into carbon dioxide,
+alcohol, and lactic acid. Small quantities of glycerine, acetic,
+succinic, and butyric acids are also formed, the casein and albumen
+being partly peptonised.[26] Keffir becomes slightly effervescent in
+twenty-four hours, and in that time develops a small quantity of
+alcohol, but after three days the amount of alcohol and lactic acid
+is much increased.[27] It has been determined that the fermentation of
+the milk is due to _Saccharomyces kefir_, and that the _Lactobacillus
+Caucasicus_ does not take any part in the fermentation, a fact which
+seems to be supported by the capacity of ordinary keffir for starting
+the fermentation in fresh milk in the same manner as the keffir grains.
+The use of this beverage seems to be universal throughout the Caucasus,
+and travellers in these regions have frequently referred to it. Thus
+Freshfield[28] states in one part of his book of travels as follows:
+
+"The pig-faced peasant against whom we had at first sight conceived such
+an unjust prejudice turned out a capital fellow. He brought us not only
+fresh milk, but a peculiar species of liquor, something between
+public-house beer and sour cider, for which we expressed the greatest
+admiration, taking care at the same time privately to empty out the
+vessel containing it, on the first opportunity." And again:
+
+"The hospitable shepherds regaled us, not only with the inevitable and
+universal airam or sour milk--if a man cannot reconcile himself to sour
+milk, he is not fit for the Caucasus--but with a local delicacy that
+has lately been brought to the knowledge of Europe--kefir. This may best
+be described as 'effervescing milk.' It is obtained by putting into the
+liquid some yellow grains, parts of a mushroom which contains a bacillus
+known to science as _Dispora caucasia_. The action of the grains is to
+decompose the sugar in the milk, and to produce carbonic acid and
+alcohol. The grains multiply indefinitely in the milk; when dried they
+can be preserved and kept for future use; its results on the digestion
+are frequently unsatisfactory, as one of my companions learnt to his
+cost."
+
+"It has been supposed," says Metchnikoff, "that the chief merit of
+kephir was that it was more easy to digest than milk, as some of its
+casein is dissolved in the process of fermentation. Kephir, in fact, was
+supposed to be partly digested milk. This view has not been confirmed.
+Professor Hayem thinks that the good effects of kephir are due to the
+presence of alcoholic acid, which replaces the acid of the stomach and
+has an antiseptic effect. The experiments of M. Rovigh, which I speak of
+in _The Nature of Man_, have confirmed the latter fact, which now may be
+taken as certain. The action of kephir in preventing intestinal
+putrefaction depends on the lactic acid bacillus which it contains.
+Kephir, although in some cases certainly beneficial, cannot be
+recommended for the prolonged use necessary, if intestinal putrefaction
+is to be overcome.... Professor Hayem prohibits its use in the case of
+persons in whom food is retained for long in the stomach. When it is
+retained in the stomach, kephir goes on fermenting, and there are
+developed in the contents butyric and acetic acids, which aggravate the
+digestive disturbances. Kephir is produced by combined lactic and
+alcoholic fermentations ... and it is the lactic and not the alcoholic
+fermentation on which the valuable properties of kephir depend; it is
+correct to replace it by sour milk, that contains either no alcohol or
+merely the smallest traces of it. The fact that so many races make sour
+milk and use it copiously is an excellent testimony of its usefulness."
+
+There are two methods given by Fl�gge[29] for the preparation of keffir:
+
+"In the first, the dry brown kefir grains of commerce are allowed to lie
+in water for five or six hours until they swell; they are then carefully
+washed and placed in fresh milk, which should be changed once or twice
+a day until the grains become pure white in colour and when placed in
+fresh milk, quickly mount to the surface--twenty to thirty minutes. One
+litre of milk is then poured into a flask, and a full tablespoonful of
+the prepared _k�rner_ added to it. This is allowed to stand open for
+five to eight hours; the flask is then closed and kept at 18� C. It
+should be shaken every two hours. At the end of twenty-four hours the
+milk is poured through a fine sieve into another flask, which must not
+be more than four fifths full. This is corked and allowed to stand,
+being shaken from time to time. At the end of twenty-four hours a drink
+is obtained which contains but little carbon-dioxide or alcohol. Usually
+it is not drunk until the second day, when, upon standing, two layers
+are formed, the lower milky, translucent; and the upper containing fine
+flakes of casein. When shaken it has a cream-like consistence. On the
+third day it again becomes thin and very acid. The second method is used
+when one has a good kefir and two or three days to start with. Three or
+four parts of fresh cows' milk are added to one part of this and poured
+into flasks which are allowed to stand for forty-eight hours with
+occasional shaking. When the drink is ready for use, a portion (one
+fifth to one third) is left in the flask as ferment for a fresh quantity
+of milk. The temperature should be maintained at about 18� C., but at
+the commencement a higher temperature is desirable. The grains should be
+carefully cleaned from time to time and broken up to the size of peas.
+The clean grains may be dried upon blotting-paper, in the sun, or in the
+vicinity of a stove; when dried in the air they retain their power to
+germinate for a long time."
+
+_Leben._--In our earlier references to fermented milks in scriptural
+times, we observed that alcoholic fermented milks were not permitted to
+be presented at the altar. Such offerings, however, were quite allowable
+amongst the ancient Egyptians, the Arabs and Carthaginians,[30] and from
+remote antiquity these nations placed great value on this product.
+Leben, which is peculiarly associated with Egypt, is a soured milk
+prepared from the milk of buffaloes, cows, or goats. It is usually
+prepared by the boiling of the fresh milk over a slow fire, after which
+some fermented milk from a previous preparation is added to the warm
+article, and the fermentation takes place rapidly and is considered to
+be complete in about six hours.[31] The Egyptian leben is valued so
+highly that it is offered in hospitality to the passing stranger, and it
+is regarded as so much of a duty to present this milk, that in some
+parts of Arabia it would be looked upon as scandalous if any payment
+were received in return.[32]
+
+_Matzoon._--Matzoon is prepared in Armenia in somewhat the same manner
+as keffir is prepared in the Caucasus, and indeed it differs very
+slightly from keffir in composition. Its use is universal in Armenia.
+
+_Dadhi._--In India large quantities of fermented milk are used, under
+the name of Dadhi, and its characteristics are not unlike the similar
+products in Europe. The specific bacillus has been investigated by
+Chatterjee,[33] who concludes that it is somewhat akin to the _Bacillus
+bulgaricus_ and the bacillus of leben (_B. lebenis_). Dr. Chatterjee
+gives a r�sum� of his investigations which sums up the whole matter
+thus:
+
+"1. The fermented milk of India called Dadhi resembles in all essential
+points the Bulgarian fermented milk as well as the leben and other forms
+of fermented milk in use in the East.
+
+"2. The causative element of the curdling process of Dadhi is a
+streptothrix having characters similar to the _Bacillus bulgaricus_ and
+_Streptobacilli lebeni_, and _Bacillus caucasina_ and the Long Bacilli
+of Mazun, in (1) not growing in ordinary media; (2) producing a large
+amount of lactic acid in milk; (3) producing, besides coagulation of
+casein and splitting up the sugar of milk into lactic acid, no other
+change in milk; (4) not producing any indol, nor peptone, nor
+saponification of fat, nor formation of any gas.
+
+"3. It differs from the above by showing peculiar pink-stained granules,
+when stained with methylene blue and showing peculiarly convoluted
+chains in glucose agar.
+
+"4. The importance of the organism lies in the fact that, as in the case
+of _Bacillus bulgaricus_, it kills all pathogenic non-sporing germs and
+also destroys all proteolytic gas-forming bacilli in milk."
+
+In the account of these investigations the following table is given,
+showing the amount of lactic acid produced by different lactic acid
+bacilli in one litre of milk, in terms of lactic acid--the culture
+being kept at 37� C.
+
+  +--------------+-------+-------+-------+-------+-------+-------------------+
+  | Name of the  | After | After | After | After | After |                   |
+  |  Bacillus.   |   24  |   48  |  72   |  96   |  a    |    Remarks        |
+  |              | Hours.| Hours.| Hours.| Hours.| Week. |                   |
+  +--------------+-------+-------+-------+-------+-------+-------------------+
+  | B. lactis    |  1.8  |  ...  | 10.08 |  ...  |  ...  | Observed by       |
+  |  �rogenes    |       |       |       |       |       |  Hall and Smith   |
+  |              |       |       |       |       |       |                   |
+  | B. coli      |  1.8  |  ...  |  4.77 |  ...  |  ...  | Observed by       |
+  |  communis    |       |       |       |       |       |  Hall and Smith   |
+  |              |       |       |       |       |       |                   |
+  | B.           | 12.8  | 16.5  | 20.2  |  ...  | 22    | Observed by       |
+  |  bulgaricus  |  -.4  |  -.4  |  -.4  |  ...  |  -.4  |  Gabriel Bertrand |
+  |              |       |       |       |       |       |  and Weisweller;  |
+  |              |       |       |       |       |       |  the initial      |
+  |              |       |       |       |       |       |  acidity of the   |
+  |              |       |       |       |       |       |  milk was 4       |
+  |              |       |       |       |       |       |                   |
+  | Matzoon Long | 10.8  | 12.   |  ...  |  ...  |  ...  | Observed by       |
+  |  st�bschen B.|       |       |       |       |       |  D�ggeli          |
+  |              |       |       |       |       |       |                   |
+  | Strepto-     |2.61[34]  ...  |  ...  |  ...  |  ...  | Observed by       |
+  |  bacillus    |       |       |       |       |       |  Rist and Khoury  |
+  |  lebenis     |       |       |       |       |       |                   |
+  |              |       |       |       |       |       |                   |
+  | Streptothrix | 10.8  |  1.08 | 11.25 | 11.70 | 18.5  | Med. Coll.,       |
+  |  dadhi       |       |       |       |       |       |  Calcutta         |
+  +--------------+-------+-------+-------+-------+-------+-------------------+
+
+In different parts of the world sour milk is consumed in great
+quantities, and it is stated by Metchnikoff[35] that the chief food of
+the natives of tropical Africa consists of soured milk, and in Western
+Africa in the region south of Angola, the natives live almost entirely
+on this product, there being a difference in the curdled milks produced
+according to the nature of the microbial flora which is introduced.
+
+It is stated[36] that in Servia, Bulgaria,[37] and Roumania there were
+5000 centenarians living in 1896, and while many reasons are advanced
+for such an abnormal condition of affairs, it seems fairly certain that
+the sole reason why people in these districts live to such great ages is
+because of their mode of living and the fact that they live very largely
+on soured milk. The hygienic conditions throughout these countries are
+not such as would give the population in the towns and villages any
+special advantages in the prolongation of life, and while it may be
+stated that a pastoral and agricultural life are likely to contribute to
+longevity, these conditions would not account for a general tendency to
+live long in the countries referred to, more than in any other
+agricultural area. There are many countries throughout the world in
+which the pastoral and agricultural existence is general, but it has
+not been shown that in these countries life is prolonged. Hence the
+conclusion has been forced upon investigators that the reason is to be
+found not in the pastoral conditions, but in the habit which has existed
+from time immemorial of consuming sour milk as a principal article of
+diet.
+
+There is no curtailment of the use of fermented milks in Eastern Europe,
+and the methods of preparation at the present day are those which have
+been carried out from time immemorial. A local observer states that in
+Bulgaria yoghourt is made in nearly every household, especially in the
+spring and summer. The method of preparation is very simple: The milk is
+boiled until a quarter of its volume has evaporated, it is then cooled
+to 45� C. and the ferment added. This ferment is a portion of the
+yoghourt of good flavour and is called "Maya" or "Zakvaska." The vases,
+a kind of earthenware pot, are enveloped in woollen stuff or sheepskin
+and placed in a warm place near the chimney. In ten hours the yoghourt
+is made, and it is preserved in a cold place. The great reputation that
+the yoghourt has acquired in Western Europe has caused this "Maya" to
+become an article of commerce. It is sent out by rail hermetically
+sealed in tinplate boxes. According to a Sophia chemist, the "Maya" is
+employed in the following manner: For a litre of milk it is necessary to
+take about 10 gr. of the ferment. This ferment is diluted with three
+times the amount of water and put into a bowl previously heated with hot
+water and dried. Into this bowl the milk, previously boiled and cooled
+to a temperature of 75� to 50� C., is poured; it is then covered over
+and put in a temperature of about 30� C., and, in default of a stove of
+constant temperature, the bowl is wrapped round with flannel or a plaid,
+and left to curdle for eight to ten hours. It is then ready for
+consumption. During winter, curdled milk keeps for several days, and in
+summer it becomes sour in from twelve to twenty-four hours.
+
+A similar food to the yoghourt is prepared in the Balkan mountains from
+sheep's milk under the name of "Urgoutnik."[38] The milk is poured into
+a goat-skin or sheepskin bag, and a little of the fermented milk added,
+and is then left for some hours in a warm place. The milk consumed is
+replaced by a fresh supply. In some of the Balkan countries, they are
+not content with the fermentation of the milk, they add a little alum,
+which, under the name of "typsa," is well known for this purpose. The
+milk attains such a solid consistency that it can be put into a cloth
+and carried to market.[39]
+
+The various forms of sour milk which have been described in the
+foregoing pages may be said to be of the traditional kind, and with the
+light of modern knowledge, it has been possible to determine exactly
+what constitutes the active principle in use in the milk consumed in
+these countries, and, as we shall see, this principle has been applied
+so that, at the present day, a pure fermented milk may be obtained in
+any country, and there is every reason to believe that should such be
+adopted as a general article of food, it would contribute to the
+prolongation of human existence.
+
+It is due to Metchnikoff, of the Pasteur Institute, that so much
+prominence has been given to the use of fermented milks. He gave it as
+his opinion[40] that senility was caused partly by auto-intoxication or
+by the poison derived from putrefactive micro-organisms which inhabit
+the digestive track. These organisms increase with age, and under
+certain unhealthy conditions multiply enormously, particularly in the
+large intestine. Having arrived at this knowledge, Metchnikoff set to
+work to devise some means of combating the influence of these harmful
+microbes, and set up the hypothesis that the tendency to longevity which
+is exhibited in Eastern countries is due to the consumption of lactic
+acid organisms in the shape of soured milk. These organisms are more
+powerful than those of a putrefactive character and inhibit their
+growth.
+
+"In the presence of such facts," says Metchnikoff, "it becomes
+exceedingly important to find some means of combating the intestinal
+putrefaction which constitutes so incontestable a source of danger. Such
+putrefaction is not only capable of producing diseases of the digestive
+tube--_enteritis_ and _colitis_--but even of becoming a source of
+intoxication of the organism in its most varied manifestations.
+
+"It is some years since I proposed to combat intestinal putrefaction and
+its injurious consequences by means of lactic ferments. I thought the
+acidity produced by such microbes would be much more effective in
+preventing the germination of putrefying microbes than the small
+quantity of acids produced by _Bacillus coli_. On the other hand, I had
+no illusion as to the difficulty sure to be encountered in any effort to
+introduce lactic microbes into the intestinal flora which has been
+preoccupied by a multitude of other microbes. To make surer of the
+result, I chose the lactic microbe, which is the strongest as an acid
+producer. It is found in the _yahourt_ (yoghourt), which originates in
+Bulgaria. The same bacillus has also been isolated from the _leben_ of
+Egypt; and it is now proved that it is found in the curdled milk of the
+whole Balkan peninsula, and even in the Don region of Russia."[41]
+
+It is a short step from considerations like these to the adoption of the
+_Bacillus bulgaricus_ as the most potent of the various lactic organisms
+which have been examined, and which is likely to play such an important
+r�le in the destiny of the human race. The _Bacillus bulgaricus_ may
+claim to be the Bacillus of Long Life.
+
+
+
+
+CHAPTER III
+
+THE CHEMISTRY OF MILK
+
+
+_The Composition of Milk._--Like all other organic substances, or those
+built up in connection with the life processes of plants and animals,
+milk is of complex composition. It is also very liable to change--every
+one is acquainted with its tendency to "go bad." This instability is
+more or less inherent in all highly organised chemical compounds, and,
+indeed, it seems to be necessary that the materials used in growth and
+nutrition should be very plastic in a chemical sense, in order, _e.g._,
+that the constituents, say of a plant, may easily be transformed into
+the substances of the body of the animal which feeds on it.
+
+The perishable nature of milk--the food of young and growing animals--is
+therefore essential, so that it may be changed easily into the blood,
+bone, muscle, etc., so abundantly required in the early stages of
+existence.
+
+Milk is a complete food, and, therefore, naturally it is not a simple
+chemical compound, but a mechanical mixture of a number of substances.
+The present state of chemical knowledge on the subject does not permit
+of its composition being given in detail, but for practical purposes,
+such as those of measuring its purity and food value, this is not
+necessary.
+
+A proximate analysis, in which, at least, some of the ingredients are
+lumped together, is sufficient, and has been adopted everywhere by
+analysts. On this basis the average composition of cows' milk may be
+stated as follows:
+
+                       Per cent.
+  Water                  87.50
+  Fat                     3.50
+  Casein and albumen      3.65
+  Milk sugar              4.60
+  Ash                     0.75
+                          ----
+                        100.00
+                        ------
+
+The constituents other than water added together form the "total
+solids," and they amount to 12.5 per cent.
+
+                       Per cent.
+  Water                  87.5
+  Total solids           12.5
+                         ----
+                        100.0
+                        -----
+
+  [Illustration: THE CONSTITUENTS OF MILK
+  In the illustration, a pint of milk is shown in a glass
+  jar, and the various percentages of water, casein, sugar,
+  ash, albumen, and fat, which make up its constituent
+  parts, are shown in separate bottles, the percentage of
+  each being stated beneath.]
+
+Milk varies a good deal in composition; the different breeds of cows
+give varying qualities. The Short-horn gives large quantities of milk of
+rather poor analysis, while the Jersey yields smaller proportions of
+very rich milk. During the period of lactation (the time which has
+elapsed since the cow gave birth to a calf), care in milking, food,
+health, etc., all have an effect on the quality of the milk.
+
+The limits of variation may be stated as follows:
+
+                            Per cent.     Per cent.
+  Water                       87.5    to    82.5
+  Fat                          2.5     "     6.0
+  Casein and albumen           3.0     "     4.5
+  Milk sugar                   3.5     "     6.0
+  Ash                          0.6     "     0.8
+
+These figures are extreme, and it is very seldom indeed that either the
+minimum or maximum is reached. Indeed, by the regulation laid down under
+Clause 4 of the British Sale of Food and Drugs Act of 1899, when the
+percentage of solids not fat falls below 8.5 per cent., and fat under 3
+per cent., it is assumed that the milk has been adulterated. This
+regulation is a perfectly just one. While genuine milk may, in rare
+instances, show figures as low as 7.1 per cent. of solids not fat, or
+2.5 per cent. of fat, the right can hardly be claimed of supplying such
+an abnormal article to the public as milk of proper quality, and the
+dairyman who understands his business, and wishes to deal fairly with
+his customers, can, by attention to the conditions enumerated above
+which influence the composition of milk, entirely avoid the production
+of such a low-grade article.
+
+In the nutrition of both plants and animals large quantities of water
+are needed. The solids must be supplied in solution or dissolved in the
+assimilative processes, and this cannot take place without water, which
+also conveys the dissolved solids to the various parts of the economy,
+and in the case of animals removes waste materials. For the most part,
+water passes through the body unchanged, but a certain proportion unites
+chemically with the food materials and assists in their digestion. It is
+therefore not surprising that seven eighths of milk is composed of
+water. Blood contains a similar proportion, and this agreement
+emphasises the fact that milk is a perfectly balanced food.
+
+The fat of milk, which yields cream and butter, differs in some
+important respects from other fats. Like these, it is made up chiefly
+of stearin, palmitin, and olein, but, in addition, it contains an
+abnormally large proportion of compounds of certain of the volatile
+fatty acids. It is these which give to butter its agreeable flavour. By
+the methods of Duclaux, the following is the approximate composition of
+butter fat:
+
+                                              Per cent.
+  Stearin, palmitin, olein, and traces of
+     myristin and butin                         91.50
+  Butyrin                                        4.20
+  Capronin                                       2.50
+  Caprylin, caprinin, and traces of laurin       1.80
+                                                -----
+                                               100.00
+                                               ------
+
+Myristin occurs in nutmegs; butyrin in another combination flavours
+pineapples and rum; caprinin is found in cocoanut fat, mutton fat, and
+in the offensive odour given off by the goat (from which the name is
+derived); caprylin is a by-product of alcoholic fermentation, and also
+occurs in cocoa fat; laurin is found in sweet bay; from which it is
+evident that there are some curious relationships in flavouring
+materials.
+
+Fats are very concentrated foods, furnishing a large amount of energy to
+the body. At one time they were classed together with starch, sugar,
+and other carbohydrates as heat-producers, but the distinction which
+was drawn between the kinds of food which were thought solely to keep up
+the temperature of the organism, and those which produced force in work
+and other forms of bodily energy, has broken down, and by direct
+experiment has been found not to exist. It is usually calculated that
+one part of fat is equal in food value to about two and a quarter parts
+of any of the other carbohydrates. Milk fat or butter is more digestible
+than almost any other fat, and its importance therefore can readily be
+realised. All the above constituents of milk fat are composed of
+different proportions of carbon, hydrogen, and oxygen, but milk also
+contains minute quantities of lecithin, a fat containing phosphorus in
+addition. Lecithin is also found in the brain and nerve material of
+animals, in the yolk of egg, and in several plants.
+
+The nitrogenous constituents of milk--casein and albumen--are usually
+estimated together, and they are reckoned as of equivalent food value.
+The name protein is very commonly applied to the total of these bodies
+in milk, or other animal and vegetable foods. They are composed of
+different proportions of carbon, hydrogen, oxygen, and nitrogen, with
+small quantities of sulphur, while casein contains phosphorus in
+addition. Albumen exists to the extent of about 0.6 per cent. in milk.
+It is very similar in properties to egg albumen. The coagulum which
+forms on the surface of milk when boiled is largely composed of albumen.
+Casein is combined with, and kept in solution by, lime, soda, and
+calcium phosphate, and its amount averages a little over 3 per cent.
+
+The remarkable property possessed by rennet, of curdling or coagulating
+casein, is well known; rennet is an extract from the stomach of the
+calf, and similar principles are present in the stomachs of man and
+other animals, so that the coagulation of milk is the first process in
+its digestion. If milk is gulped down in large quantities it is apt to
+coagulate in lumps, and digestion is much interfered with, but if it is
+taken hot and slowly, it coagulates in small pieces which are readily
+attacked by the gastric juice, and milk is then one of the most
+assimilable of foods.
+
+Nature provides that the milk for young animals is supplied in finely
+divided streams, so that coagulation takes place in the best possible
+way.
+
+The proteids are the most important constituents of food; they are
+abundant in the blood, and build up the muscles, brain, nerves, and
+other bodily structures.
+
+Besides these mentioned, milk contains traces of another proteid of
+similar composition called globulin.
+
+The sugar of milk is not found anywhere else. It is a carbohydrate like
+cane and grape sugar--that is to say, the hydrogen and oxygen they
+contain are in the same relative proportions as in water. Milk sugar is
+not so soluble or so sweet as the other sugars. It does not ferment with
+ordinary yeast, but certain special yeasts which are made use of in the
+preparation of keffir, koumiss, etc., have the power of transforming it
+into alcohol. Its most remarkable property, however, is the facility
+with which, under the influence of certain bacteria, it is changed into
+lactic acid.
+
+Every one is familiar with the souring of milk, but perhaps it is not so
+generally known that there are great differences in the results obtained
+in accordance with the conditions under which the souring takes place.
+The skilled butter-maker, by keeping the milk in a cool and cleanly
+dairy, obtains a sour milk of a characteristic and agreeable aroma and
+taste, which beneficially affect the flavour of the butter produced. On
+the other hand, if milk is kept in hot and dirty surroundings, the
+development of acidity is accompanied by different bad tastes and
+odours, and it becomes unfit for use as a food. In the first case, the
+conditions are favourable to the maximum production of the lactic acid
+bacteria, and these occupy the field, and largely prevent the
+development of the other bacteria which are present--the survival of the
+fittest in the struggle for existence. In the second case, the impure
+surroundings swarm with the germs of many kinds of putrefactive
+bacteria, and the high temperature assists these to gain the upper hand.
+Again, the survival of the fittest, in the particular conditions. Even
+in cool and cleanly surroundings injurious taints may develop,
+especially if the milk has previously been subjected to a journey by
+road or rail, as is the case in the modern creamery system, where the
+farmers deliver their milk to a central creamery, where it is made into
+butter. In such establishments it is the regular practice to kill the
+germs, lactic and others, existing in the milk, by heating it to a high
+temperature. This process is called pasteurising, after the great French
+chemist and bacteriologist who invented it. Pure lactic cultures are
+added to the pasteurised milk, and the souring process is under exact
+control, with the result that butter of uniform flavour and quality is
+produced. The same method is made use of in making the special sour milk
+described in this book, with, of course, modifications in the apparatus
+employed, to suit the smaller scale in which the manufacture is
+conducted.
+
+The ash is the mineral matter which is left when milk, previously dried,
+is burnt in a crucible. It is a complex mixture, and, as we have seen,
+it amounts to about 0.7 per cent. of the milk. The process of burning
+destroys all the organic matter, and, at the same time, alters somewhat
+the state of combination of the inorganic or mineral elements. Attempts
+have been made from the analysis of the ash to reconstitute the
+composition of the mineral matter as it exists in the milk. The best
+known is that of Soldner, and the following is his calculation:
+
+                                             Per cent.
+  Sodium chloride                              10.62
+  Potassium chloride                            9.16
+  Monopotassium phosphate                      12.77
+  Dipotassium phosphates                        9.22
+  Potassium citrate                             5.47
+  Dimagnesium citrate                           3.71
+  Magnesium citrate                             4.05
+  Dicalcium phosphate                           7.42
+  Tricalcium phosphates                         8.90
+  Calcium citrate                              23.55
+  Calcium oxide, in combination with casein     5.13
+                                              ------
+                                              100.00
+                                              ------
+
+The presence of citrates will be noted in this analysis. Citric acid,
+which gives to lemons their acidity, and is also found in other fruits,
+has been proved to exist in milk to the extent of about 0.2 per cent.
+When alkaline or earthy citrates are burnt or oxidised in the blood, the
+citric acid is destroyed, and corresponding carbonates remain. No doubt
+the function of citrates in milk is to furnish to the body the earthy
+and alkaline carbonates which are required in certain of its parts.
+
+The mineral constituents of milk have many important functions to
+perform in the building up and nutrition of the bodily organism.
+Phosphate of lime is the principal constituent of the skeleton, and the
+blood must be richly supplied with the alkalies, earths, and acids which
+are comprehended in the ash.
+
+Milk contains traces of many other substances, the most important of
+which are several enzymes which assist in its digestion.
+
+_General Properties of Milk._--The appearance of milk is known to every
+one; it ought to be a pure white opaque liquid, but very generally it is
+tinted a cream colour with anatto to give it an added appearance of
+richness. The average specific gravity is about 1.031; or, to put it
+another way, while a gallon of pure water weighs exactly 10 lbs., a
+gallon of milk weighs 10 lbs. 5 oz. It freezes at 31� F. and boils at
+about one third of a degree higher than water.
+
+When milk is examined under the microscope, the fat is found to be
+distributed through it in a multitude of minute globules varying in size
+from 1/16,000th to 1/25,000th part of an inch, and occasionally they are
+much smaller and also much larger.
+
+Fig. 1 is a micro-photograph showing the fat globules in whole milk.
+Fig. 2 is a micro-photograph of separated milk, and Fig. 3 a
+micro-photograph of cream, all under high magnification (450 diams.);
+from these figures the comparative number of fat globules present may be
+seen.
+
+  [Illustration: FIG. 1.--Micro-photograph of a Drop of
+  Whole Milk, showing distribution of fat globules.
+  (Magnified 450 diams.)]
+
+  [Illustration: FIG. 2.--Micro-photograph of Separated
+  Milk, showing the almost complete absence of fat globules
+  as compared with whole milk. (Magnified 450 diams.)]
+
+  [Illustration: FIG. 3.--Micro-photograph of Cream, showing
+  agglomeration of fat globules. (Magnified 450 diams.)]
+
+Fats distributed through a watery liquid in this finely divided
+condition form together what is called an emulsion, in which the
+particles of fat are kept apart by surface tension. The specific gravity
+of milk fat averages 0.93, and compared with water weighing 10 lbs., a
+gallon of fat would weigh 9 lbs. 5 oz. It is thus considerably
+lighter than the other constituents, and when milk is left at rest, the
+fat globules gradually rise to the top and float there, forming cream.
+The difference in specific gravity between cream and milk is taken
+advantage of in the mechanical separator, now so much used, and which
+makes such a thorough separation between the two. Cream is an article of
+the most varied composition, according to the ideas of the person who
+produces it, but it ought to contain at least 20 per cent. of butter
+fat, and may be made with a much larger percentage if necessary. When
+cream is agitated in a particular way, as by churning, the surface
+tension of the particles is overcome, and they run together into a mass
+which forms butter.
+
+The casein of milk is not held in solution in the ordinary sense, but in
+a peculiar state of suspension called the colloidal condition,
+practically the whole of it remaining behind when milk is filtered
+through clay filters.
+
+It is this state of suspension of the casein which makes milk opaque,
+but the opacity is considerably increased by the emulsified fat.
+
+The coagulation of the casein in milk by the addition of rennet has
+already been referred to. Acids, either mineral or organic, also
+precipitate it in the form of flakes. Skimmed milk is now largely used
+for the preparation of casein by this method, and the washed and dried
+precipitate is used very extensively in the arts for such varied
+purposes as the manufacture of billiard balls, paints, cements, etc.
+
+The clear liquid which separates when milk is curdled with rennet is
+called whey, and contains the milk sugar and mineral salts. The sugar is
+manufactured from it on a limited scale, and is used as an ingredient in
+infant foods, and as a convenient medium in certain medical
+preparations. In Sweden a kind of cheese is made from whey, but the
+great bulk of it everywhere is used for feeding pigs.
+
+The comparative composition of different varieties of milk is given in
+the following table:
+
+  -------------------------------------------------------------------------
+             Human   Cow   Buffalo  Goat  Sheep   Mare   Ass Reindeer Whale
+  -------------------------------------------------------------------------
+  Water      88.32  87.75   82.57  86.34  81.08  90.38  90.30   67.7  60.47
+  Fat         3.43   3.40    7.63   4.25   7.67   1.00   1.30   17.1  20.00
+  Protein     1.55   3.50    4.69   4.40   6.08   1.98   1.80   10.9  12.42
+  Milk Sugar  6.44   4.60    4.30   4.26   4.26   6.28   6.20    2.8   5.63
+  Salts       0.26   0.75    0.81   0.75   0.91   0.36   0.40    1.5   1.48
+  -------------------------------------------------------------------------
+  Total     100.00 100.00  100.00 100.00 100.00 100.00 100.00 100.00 100.00
+  -------------------------------------------------------------------------
+  Specific   1.032 1.0315   1.033  1.033  1.038  1.034  1.033   ...   ...
+   Gravity
+  -------------------------------------------------------------------------
+
+  [Illustration: FIG. 4 is a photograph of two Petri dishes,
+  which have been inoculated with ordinary milk (A), and
+  milk that has been subjected to sterilisation (B). The
+  whitish bacterial colonies on A are due to enormous
+  numbers of organisms, while B is quite free from such
+  growth.
+
+  For the production of a reliable lactic food, it is
+  essential that certain precautions as to the treatment of
+  the milk, and the maintenance of a suitable temperature
+  during the growth of the lactic bacteria, should be
+  observed.
+
+  In the first place, milk immediately after extraction from
+  the cow contains only a few organisms, but these multiply
+  so rapidly that in a few hours the bacterial content may
+  amount to many millions per ounce. In preparing a pure
+  culture of any specific organism, then, care must be taken
+  to destroy all the bacteria that have accidentally found
+  their way into the milk, inoculating with the organisms it
+  is desired to cultivate. This is best accomplished by
+  heating the milk to the boiling-point of water for about
+  thirty minutes, by which time almost all the undesirable
+  bacteria have been killed.]
+
+The milk of the cow differs a good deal from human milk, and where the
+former is used for the feeding of children it is usual to add milk sugar
+to it, and otherwise alter it to bring its composition more in harmony
+with the human article. The high concentration of the milk of the
+reindeer and the whale is noteworthy. Perhaps this may be due to the low
+temperature conditions in which these animals live, necessitating strong
+nutriment to enable their young to make proper progress in growth and
+development. On the other hand, the milk of the ass is poor in quality,
+and probably on this account it is more readily assimilated by those of
+weak digestion, to whom it is sometimes recommended. Goats' milk is
+richer than either cow or human milk, and its nourishing properties are
+well known. The goat is usually free from tuberculosis and other
+diseases which affect the cow, and its milk is therefore a very safe
+article to use.
+
+_The Analysis of Milk._--While the analysis of milk can only be made by
+a competent chemist, there are a number of simple tests and observations
+by which any intelligent person can obtain a fair idea of its quality.
+The taste and smell afford some guide, as also the general appearance.
+To judge of the latter, place some of the milk in a tumbler or other
+clear glass vessel. If the milk is of good quality it will be quite
+homogeneous and opaque. Any flocculent matter indicates either disease
+in the cow or that the milk is old and bacteria have multiplied in it
+and altered its composition. When the milk has stood long enough for the
+cream to rise freely, the latter should form a perfectly homogeneous and
+strongly defined layer on the top. The quantity of cream may be measured
+in a creamometer, which consists of a small glass cylinder graduated at
+the top (Fig. 5). It is filled with milk to the top graduation line, and
+when the cream has risen, the percentage quantity of the latter which
+has separated can be taken off.
+
+  [Illustration: FIG. 5. The Creamometer]
+
+The colour should be like that of porcelain, but, as already stated, it
+is a common thing for the dairyman to add a small quantity of anatto or
+an aniline dye of a similar shade, to give the milk a rich creamy tint.
+If the milk is of a reddish colour this may be caused by blood from the
+udder, although certain foods, such as beets, mangels, and carrots
+sometimes give a similar tint. The milk given by cows immediately after
+calving is called "colostrum" or "biestings," and is of a yellow or
+yellow-brown colour. It is much thicker than ordinary milk, and
+coagulates in boiling.
+
+In dirty byres in which care is not taken in milking, quite considerable
+quantities of hairs, pieces of manure, and other filth may get into the
+milk. Usually the milk is strained by the dairyman, but sometimes this
+is omitted or carelessly done. To test for dirt, a ribbed glass funnel
+is useful. Get a piece of the finest muslin about twice the diameter of
+the funnel, fold over twice, so that it becomes one quarter of its
+original size; open one of the sections and place in the funnel; pass
+the milk into this. It will run through quickly and some water may be
+run into the funnel to clear away the last traces of milk. The filter
+cloth can then be opened out and any dirt retained will become visible.
+The apparatus is shown in Fig. 6.
+
+  [Illustration: TESTING-GLASS FOR EXTRANEOUS MATTER IN
+  MILK.
+
+  FIG. 6.--A piece of muslin is folded as shown and a
+  measured quantity of milk is passed through the funnel;
+  from the sediment left in the muslin, the percentage of
+  extraneous matter may be arrived at.]
+
+If a glass funnel is not available, a very small jelly bag can be made
+of fine gauze and used in the same way. The washing water should be used
+in small quantities and directed to concentrating the dirt in the apex
+of the bag. After washing, the latter can be turned outside in, to
+permit of readier examination of the dirt. The bag should be well
+washed in cold water, then boiled and dried, and is then ready for
+future use.
+
+The acidity of milk is a very useful guide to its age. Milk has the
+curious property of being "amphoteric," _i.e._, it is both slightly acid
+and slightly alkaline when fresh. As its age increases, however, so does
+its acidity, and at a rate varying with the temperature and moisture
+contents of the atmosphere in which it is placed. Old and acid milk is
+heavily contaminated with bacteria, a proportion of which are likely to
+be injurious to health.
+
+  [Illustration: FIG. 7. Lactometer and Test Tube]
+
+The simplest method of testing the acidity is to procure a few little
+books of blue and red litmus test papers, and these can be had from any
+philosophical instrument maker or laboratory furnisher. The strips of
+test paper are torn out and dipped in the milk. When the milk is quite
+fresh it will, owing to its amphoteric condition, change the red litmus
+paper slightly blue, and the blue litmus paper slightly red. Old milk
+changes blue litmus paper to a bright red because of its decided
+acidity.
+
+The above tests do not indicate if the milk is poor or rich, but this
+can be determined by the lactometer, an instrument for ascertaining in a
+simple way the specific gravity. The lactometer is shown in Fig. 7.
+
+It is graduated usually from 25� to 36�, corresponding to specific
+gravities 1.029 to 1.038. It is graduated to degrees and half degrees.
+Sometimes a thermometer is combined with the instrument. The specific
+gravity rises as the temperature is lowered and decreases with increase
+of temperature, so that it is important to make the test at the figure
+at which the lactometer was graduated, which is usually 60� F. Failing
+this, an allowance has to be made for higher or lower temperatures. The
+milk to be tested is well mixed, and placed in a deep vessel, and the
+lactometer placed in it, holding it at first at an angle. It stands
+upright and remains deeper or higher according to the specific gravity.
+The reading is taken on the stem at the level of the milk. As the latter
+is drawn up a little round the stem, about a half degree should be added
+on to get the true figure. Thus, if the apparent reading is 31, the true
+reading may be taken as 31.5. This is the average figure for good milk,
+corresponding to a specific gravity of 1.0315; anything above this is
+all to the good. Lower readings mean inferior quality, the latter being
+proportionate to the lowness of the readings. The tests are most
+conveniently made in a glass cylinder (Fig. 7), which may be purchased
+with the lactometer. As there are many inaccurate instruments in the
+market, it is necessary to go to a reputable maker, because an
+unreliable lactometer is worse than useless.
+
+The following table gives, in a condensed form, the allowances to be
+made when the temperature is above or below the standard (60� F.):
+
+  ------------+----------------------------------------------------------
+  Temperature.|               Reading of Lactometer.
+  ------------+------------------------------------------------------------
+     Degs. F. |
+       40     | 23.5 24.5 25.5 26.4 27.3 28.2 29.1 30.0 31.0 31.9 32.8 33.7
+       45     | 23.8 24.8 25.9 26.8 27.8 28.6 29.3 30.4 31.3 32.3 33.2 34.2
+       50     | 24.1 25.1 26.1 27.0 28.0 29.0 29.9 30.9 31.8 32.8 33.7 34.7
+       55     | 24.5 25.5 26.5 27.5 28.5 29.5 30.4 31.4 32.4 33.4 34.3 35.3
+  ------------+------------------------------------------------------------
+       60     | 25.0 26.0 27.0 28.0 29.0 30.0 31.0 32.0 33.0 34.0 35.0 36.0
+  ------------+------------------------------------------------------------
+       65     | 25.5 26.6 27.6 28.7 29.6 30.7 31.7 32.8 33.8 34.8 35.8  ...
+       70     | 26.1 27.2 28.2 29.3 30.2 31.3 32.4 33.4 34.5 35.5 36.5  ...
+       75     | 26.8 27.8 28.8 29.9 30.8 32.1 33.1 34.2 35.2 36.3  ...  ...
+       80     | 27.4 28.4 29.5 30.7 31.6 32.8 33.9 35.9 36.1  ...  ...  ...
+  ------------+------------------------------------------------------------
+
+Thus if the thermometer indicates 40� F., and the lactometer 29.1�, the
+true reading at the standard temperature of 60� F. is 31�, corresponding
+to a specific gravity of 1.031. Intermediate figures can readily be
+averaged. Care should be taken to wash the lactometer with cold water
+under the tap, as otherwise the milk will dry on it and render it
+inaccurate.
+
+
+
+
+CHAPTER IV
+
+HANDLING OF MILK
+
+
+MODERN DAIRY PRACTICE
+
+As we have seen, the dairy industry is a very ancient one, and has been
+intimately associated with the development of civilisation.
+
+Within historical times dairying has always formed a prominent feature
+in connection with agriculture, and the use of milk in one form or
+another has been common to every civilised nation.[42]
+
+The greatest progress, however, in the study of milk has taken place
+since about the year 1890, at which time the dairy industry seems to
+have attracted the general attention of food specialists and scientific
+investigators throughout the world. Since then it has been considered
+worth while to enact laws in different countries with regard to the
+regulation and control of the milk supply.
+
+Since 1903 there has been an International Dairy Federation formed, and
+it has held conferences at Brussels, Paris, The Hague, and Buda-Pest,
+and in 1911 it will hold a conference in Stockholm. The Federation was
+started in a very humble way in Brussels, and owes its origin, to a
+large extent, to a distinguished Belgian agriculturist, Baron Peers of
+Oostcamp, Bruges; but at the present day a general committee composed of
+representatives of nearly every civilised nation has been formed, and
+delegates from such countries attend the Congresses, which are held
+every two years. The literature which has arisen out of these
+International Congresses has been disseminated in different countries,
+and has been instrumental in placing the dairy industry on a thoroughly
+scientific basis.
+
+_Milk Supply of the United Kingdom._--The milk supply of the United
+Kingdom has steadily grown from year to year, and in relation to the
+population works out at fifteen gallons per head. The manner in which
+these figures are arrived at is shown in the following estimate:
+
+  The population of the United Kingdom is now about
+  45,500,000. The number of cows or heifers in calf or in
+  milk in June, 1909, was 3,360,600; the number in 1910 was
+  probably about 4,400,000.
+
+  Of these about 300,000 were heifers that had not yet
+  produced any milk. The actual milking class, therefore,
+  comprised about 4,100,000 cows and heifers; of these,
+  about 600,000 were heifers that calved in the winter and
+  spring of 1909-10, and 300,000 were heifers that calved in
+  the summer and autumn of 1910. The number of cows that
+  produced two or more calves may be taken to be about
+  3,200,000; of these about 600,000 should have produced
+  their second calf in the winter and spring 1909-10, and
+  would be milked as heifers in the summer and autumn of
+  1910; the number of mature cows from which a full season's
+  supply of milk was obtained during the twelve months from
+  June 5, 1909, to June 4, 1910, was apparently about
+  2,600,000. A large quantity of milk is yielded during the
+  year by cows sold or lost during the twelve months before
+  the census. Possibly ten per cent. of the milk produced in
+  the twelve months from June, 1909, to June, 1910, was
+  yielded by cows that were sold or lost before the census
+  of June, 1910.
+
+  It is estimated that the 3,200,000 cows (including the
+  600,000 that up to the winter of 1909-10 were heifers)
+  produced, on the average, 44 cwts. (480 gallons) of milk
+  per head in the twelve months from June 5, 1909, to June
+  4, 1910; the 300,000 heifers that calved in the summer and
+  autumn, 30 cwts. (330 gallons) per head; the 600,000
+  heifers that calved in the winter and spring of 1909-10,
+  15 cwts. (165 gallons), making the total quantity of milk
+  produced in the twelve months by cows and heifers on the
+  farms, and that produced calves during the twelve months
+  (June, 1909-1910), 158,800,000 cwts. (1,746,800,000
+  gallons), or about 426 gallons per head, and about 400
+  gallons per head for all the cows and heifers in milk or
+  in calf in 1910. There remains to add the milk yielded by
+  the cows that were sold during the twelve months, and of
+  cows and heifers in feeding pastures that were milked
+  during the twelve months, June to June, 1909-10, and which
+  probably formed one tenth of the whole supply, making the
+  total supply for the twelve months 176,444,000 cwts., or
+  1,940,884,000 gallons. This equals 2 tons, or 440 gallons
+  per head, crediting the whole supply to the 4,400,000 cows
+  and heifers in milk or in calf in June, 1910. At 7-1/4d.
+  per gallon the value of milk produced in the United
+  Kingdom in the twelve months was �58,600,000. Including
+  the value at birth of the calves, the total value of the
+  produce of the milk-giving class would be about
+  �62,000,000. The value of the milk, butter, cheese, and
+  cream sold or consumed in farmhouses would be about
+  �48,000,000, or equal to about 24 per cent. of the gross
+  annual income of farmers.
+
+  The average consumption of new milk is about 15 gallons
+  per head of the population. During the twelve months of
+  1911, the quantity required for this purpose will be about
+  682,500,000 gallons, or about 35 per cent. of the total
+  supply; calves will require about 10 per cent. of the
+  supply; the quantity available for butter and cheese will
+  equal about 55 per cent. of the supply.[43]
+
+_The Milk Industry in the United States._--In the United States of
+America, where the habits of the people are somewhat analogous to those
+in the United Kingdom, it is estimated that the milk from five million
+cows is annually consumed, which averages twenty-five and one half
+gallons per year for each person, or equal to an ordinary sized
+tumblerful each day.[44]
+
+Such a vast industry, so intimately associated with the food of the bulk
+of the people, naturally invites the closest study, and, as a
+consequence, the literature on the subject, which has arisen during the
+last twenty years, has been of a voluminous character, not only from the
+point of view of practice, but from that of bacteriology, chemistry, and
+hygiene.
+
+A pure milk supply is essential to health, and it seems unfortunate that
+the ordinary milk producer should, in a great many cases, take up an
+antagonistic attitude to the scientific methods of handling milk. There
+is a body of opinion being created, however, which is likely to alter
+this attitude in the next generation, and this is attributable to the
+fact that so much excellent work has been done at numerous dairy
+colleges and institutes in all civilised countries that the dairy
+industry is emerging from a period of rule-of-thumb procedure to its
+proper place as one of the technical arts.
+
+_Transmission of Disease in Milk._--It is not to be wondered at that the
+handling of milk should now be regarded as a technical business, seeing
+that milk-borne disease is one of the commonest with which we have to
+deal.
+
+The commoner diseases which have been transmitted by milk are scarlet
+fever, typhoid, diphtheria, tuberculosis, sore throat epidemics. Others
+of a more complex character have been traced to the same source of
+infection, and the clearest possible evidence has been furnished of the
+transmission of diseases by means of micro-organisms, which have
+contaminated the milk supply.
+
+It is therefore necessary to watch over the milk from the source of
+supply to its consumption. It is primarily on the farm and in the
+cow-house that methods of handling in a hygienic way should be insisted
+on, as microbial contamination increases at a prodigious rate, and it is
+the early microbe therefore which does the most damage.
+
+The milk in the udder, for all practical purposes, may be assumed to be
+sterile, and the contamination which takes place originates, therefore,
+from external sources.
+
+One of the principal means of infection is from hairs which fall from
+the cow into the milk, and many of which are carriers of dangerous
+micro-organisms.
+
+There is also a certain amount of offensive dirty matter which may fall
+into the milk-pail, and carry with it undesirable germs.
+
+These impurities may, to a certain extent, be eliminated by good
+straining, but a surer prevention is to have the cow-house perfectly
+clean and free from dust, as dust specks are in many cases the vehicles
+of disease germs. Cleanliness is, in fact, the essential feature in
+modern dairying, not only in the cow-house, but in the milking utensils,
+the drainage, etc., and, above all, the milker should be of cleanly
+habits.
+
+The flavours of milk sometimes arise from the absorption of
+evil-smelling gases in the cow-house, or from a peculiar taint from
+certain roots and feeding stuffs, and in such a case it is desirable
+that a�ration should take place in a fresh clear atmosphere, so that
+oxygenation may have the effect of eliminating and destroying the
+foreign odours and flavours which may be present. If this process of
+a�ration is carried out at blood heat, the result is generally highly
+satisfactory.
+
+_Milk Management._--There have been many excellent tables of rules
+published for the management of dairies in different countries, but they
+are necessarily framed within certain limitations which apply to all.
+The following is an excellent set, which put concisely the conditions
+necessary to be observed in the modern cow-house:
+
+   1. The cow should be sound--no disease should exist in
+        the animal.
+
+   2. The feed should be good and free from aromatic
+        substances. If these aromatic foods are used, they should
+        be employed according to those methods which will not
+        cause odours or flavours to appear in the milk.
+
+   3. The cow should be groomed, and hair about the udder
+        preferably clipped.
+
+   4. The udder should be moistened during milking.
+
+   5. The milker should be a neat, tidy person.
+
+   6. The milker should be free from disease, and should not
+        come in contact with any communicable disease.
+
+   7. The milker's clothes and hands should be clean while
+        milking.
+
+   8. The pail should be sterilised.
+
+   9. The stall should be such as to reduce the amount of
+        disturbance of dust and dirt.
+
+  10. There should be good light, good ventilation, and
+         good drainage in the cow-house.
+
+  11. The cow-house should always be kept clean.
+
+  12. Feeding and bedding, unless moist, should be done
+        after milking.
+
+  13. A dustless milking-room is desirable.
+
+  14. Milk should not stand in the cow-house.
+
+  15. If milk is a�rated, it should be done before cooling
+        and in pure air.
+
+  16. The sooner the milk is cooled after milking the
+        better.
+
+  17. Keep the milk as cold as possible when once
+        cooled.[45]
+
+The supply of milk is conducted, to a large extent, by towns' dairies,
+which depend for their supplies upon the dairy farm in the country, and
+it is obvious that a certain period of time must elapse, in the
+generality of cases, before a town's dairy receives its supply in the
+ordinary course, and this constitutes the greatest difficulty in modern
+dairy practice, owing to the liability of the milk to absorb bacteria,
+which during transit may multiply enormously.
+
+The multiplying of bacteria in milk at different temperatures is easily
+demonstrated, and the result of this has been stated in various forms
+many times over. As a graphic means, however, of showing the increase
+that takes place in the numbers of germs present, and the consequent
+product of acidity, the table below by Conn may be given.
+
+The consequent result of the increase in bacteria is the production of
+lactic acid, which produces the souring so familiar in milk which has
+been kept in the household at a high temperature.
+
+  _Numbers of Bacteria per c.cm. in Milk kept at
+             Different Temperatures._
+
+  --------------------------------------------------------------------------
+  Number  In 12   In 12    In 50    In 50 hrs. or at   No. hrs.   No. hrs.
+  at     hrs. at hrs. at  hrs. at   time of curdling   to curdle  to curdle
+  Outset  50� F.  70� F.   50� F.   at 70� F.           at 50� F.  at 70� F.
+  --------------------------------------------------------------------------
+  46,000 39,000 249,500 1,500,000   542,000,000            190        56
+  47,000 44,800 360,000   127,500   792,000,000.36 hrs.    289        36
+  50,000 35,000 800,000   160,000 2,560,000,000.42 hrs.    172        42
+  --------------------------------------------------------------------------
+
+What actually happens is that the lactic acid is produced by the
+breaking up of the milk sugar, and the appearance of this sourness is an
+indication that a period has been reached in the age of the milk which
+may be described as being--unwholesome.[46]
+
+It is necessary, therefore, for the town's milk dairy to be equipped in
+such a way as to deal promptly with the milk supply.
+
+We have seen that the milk should first of all be a�rated at blood heat,
+so as to liberate objectionable odours, after which it should be cooled
+to as low a temperature as possible, by means of well water. When these
+operations have been performed on the farm, milk should be sent as
+rapidly as possible to the distributing towns' dairies, and should be
+transported in refrigerated waggons, cooled preferably with ice, during
+the journey. On arrival at the town dairy, it will be necessary to
+pasteurise the milk--that is to say, the milk should be heated to such a
+temperature as will destroy any pathogenic organisms which may be
+present, and the pasteurising temperature should therefore be in excess
+of the thermal death-point of all such organisms.
+
+Pasteurisation owes its origin to Pasteur, and has become an adopted
+method throughout the dairy industry, and there are many mechanical
+devices termed "pasteurisers" (see Fig. 8) which are used for the
+carrying out of this particular operation. The form of one of these is
+that of a vertical jacketed cylinder with paraboloidal surface, around
+which steam is made to pass, so as to maintain the temperature at about
+176� F. Milk is allowed to flow in at the bottom of the paraboloidal
+surface, and is caught by mechanical agitating arms, which revolve at a
+given speed, and by this action milk is distributed centrifugally over
+the paraboloidal surface, and is forced out by the same action, at the
+top of the apparatus, after being heated.
+
+  [Illustration: PASTEURISER
+
+  FIG. 8.--The milk enters from the bottom and circulates to
+  the top of the inside cylinder, which is paraboloidal in
+  construction. It is heated as it passes through the
+  apparatus, and is discharged at the top at a temperature
+  of 176� F.]
+
+The centrifugal action is sufficient to raise the milk some three to
+four feet, through a tube, and this is taken advantage of so as to cause
+the milk to flow over a conical cooler, described as a primary cooler,
+and in which water is made to circulate. As the hot milk descends over
+the conical cooler it gives up most of its acquired heat to the water,
+and, in practice, is reduced in temperature to within 4� of the
+temperature of the water.
+
+Below this primary cooler is fixed a cooler of the same size and shape,
+which is termed a secondary cooler. In it, brine at a temperature of
+about 35� F. is circulated from a refrigerating machine, and, as the
+milk falls over the secondary cooler, it is cooled to a temperature of
+about 40� F., when it may be looked upon as being pasteurised and free
+from all pathogenic organisms, in which state it will keep for a
+considerable length of time.
+
+It is desirable that the milk should, as soon as possible after the
+cooling takes place, be delivered to the consumers, and be kept under
+cool conditions, either in bottles or in a closed vessel covered over
+with muslin, so as to keep out specks of germ-laden dust.
+
+Briefly speaking, the foregoing is an outline of what is carried on in
+the ordinary dairy practice.
+
+There are many modifications of this practice, such as the introduction
+of regenerative heaters, so as to utilise a portion of the heat of
+pasteurisation, which would otherwise be wasted.
+
+In some cases, again, it is considered necessary to conduct the primary
+and secondary cooling over coolers furnished with mantles, so that the
+atmospheric bacteria which are everywhere present should be shut off
+from the falling milk.
+
+Ordinarily, however, the equipment for a town's dairy consists of:
+
+1. Steam-boiler to generate steam for pasteurising, scalding, etc.
+
+2. Motive power, which may be either a steam-engine, gas-engine, or
+electric motor.
+
+3. Refrigerating machine, which is used for supplying cold brine to the
+secondary cooler. In many cases it is also used for cooling a room in
+which the milk and cream are stored.
+
+4. Milk-receiving tank.
+
+5. Milk-strainer.
+
+6. Pasteurising apparatus, and primary and secondary coolers.
+
+Such a plant is necessary in order to conduct an ordinary town dairy
+business in anything like a hygienic way, and is designed only for the
+handling of milk intended for domestic consumption.
+
+There are times when another plant might be necessary, such as a plant
+for the separation of milk, or for utilising it for the production of
+butter or cheese, such operations being subject to the fluctuations in
+the milk supply.
+
+It is sometimes desirable also to use up an excess of milk for cheese or
+butter-making; hence it is necessary to provide such apparatus as has
+been indicated.
+
+_Preparation of Soured Milk._--The foregoing description has been given
+in some detail, as showing the ordinary practice, and we now come to
+consider how it can be modified so as to provide for the production of
+soured milk. It may first of all be premised that within the next few
+years the preparation of soured milk as an ordinary production of the
+dairy will be universal, and will form a part of the ordinary dairy
+practice. The apparatus, therefore, which is necessary is one of
+considerable interest to all who are engaged in the dairy industry.
+
+As will be seen from the chapter describing the preparation of soured
+milk in the dairy, this process can be conveniently carried on, so as to
+utilise the plant which is at present in general use. The milk can be
+received in the same way, pasteurised and cooled to about blood-heat,
+after which its preparation as soured milk is a very simple matter, and
+only requires a certain amount of careful attention.
+
+For the keeping of soured milk, a cold room cooled by a refrigerating
+machine would be desirable, so as to maintain the fermented milk at a
+low temperature and prevent over-fermentation.
+
+Apparatus has been designed so as to handle soured milk on a large
+scale, and one of the machines is shown on the illustration (see Fig.
+9). It is simply a jacketed cylinder with a cover and an agitating gear.
+The inside of the machine is nickel-plated, and there is an arrangement
+whereby the cooling may be done rapidly, through a coil inside the
+jacket, this coil being connected to the brine circulation of the
+refrigerating machine.
+
+  [Illustration: CONTINUOUS APPARATUS FOR THE PRODUCTION OF
+  LARGE QUANTITIES OF SOURED MILK
+
+  FIG. 9--This apparatus is made by the Dairy Machinery and
+  Construction Company of Shelton, Conn., U S A. The milk is
+  agitated inside a jacketed cylinder, where it is allowed
+  to incubate at about blood heat. The milk can be rapidly
+  heated and also rapidly cooled by means of this
+  apparatus.]
+
+The machine is filled with milk containing three per cent. of fat, which
+has been previously pasteurised to about 190� F., and cooled down to
+about 90� F.; at this point the pure culture of _Bacillus bulgaricus_ is
+introduced, and the agitator is kept working, so as to mingle it
+thoroughly with the milk. The agitator is then stopped until the acidity
+shows a test of 0.9 to 1.0 per cent., when the agitator is again
+started, and cold brine from the refrigerating machine is turned on to
+the cooling pipes, so that the product is thoroughly broken up, and
+cooled down to 40� F.
+
+The milk is then transferred to a bottle-filling machine (Fig. 10),
+poured into bottles and hermetically sealed, after which it is ready for
+consumption. When it has to be kept for any time it should be placed
+in a cold room where there is a temperature not higher than 40� F.
+
+The process, therefore, is a simple one, and lends itself to the
+ordinary dairy business, without involving any great expenditure on
+account of a new plant.
+
+
+
+
+CHAPTER V
+
+THE BACTERIOLOGY OF FERMENTED OR SOURED MILK
+
+
+A CHAPTER FOR STUDENTS
+
+During the last few years much work has been done in investigating the
+action of various classes of organisms--bacteria, yeasts, and
+moulds--upon milk and its products. While, however, the attention of the
+dairyman has been chiefly directed to the propagation of acid-producing
+organisms and the use of pure cultures of lactic acid bacteria in their
+relation to butter and cheese making, a new sphere in micro-biology has
+been disclosed by the study of the effects caused by the combined growth
+of two or more different classes of organisms in milk and the consequent
+production of lactic, alcoholic, and gaseous fermentations. The
+simultaneous occurrence of these fermentative changes is responsible for
+the formation of such beverages as keffir, koumiss, milk-wine, etc. It
+has therefore become essential, in connection with the study of new
+developments in the milk industry, that we should make a more intimate
+acquaintance with the bacteriology of the ferments involved.
+
+_Keffir_ (_kephir_, _kifyr_, _kiafyr_, _kephor_, _kyppe_) is the name
+given to an acid, slightly alcoholic drink, which for many centuries has
+been prepared by the nomadic tribes in the Caucasus. The characteristic
+fermentation is induced by the addition of so-called keffir grains.
+These are yellow or golden-yellow, warty, and furrowed flakes or
+nodules, the former varying in size from that of a rice grain to that of
+a bean, while the latter are often about an inch across and one eighth
+of an inch thick. Bearing in mind the fact that the preparation of
+keffir has been carried on for many centuries, it is not surprising that
+the origin of these grains should be surrounded by myths.
+
+The belief is prevalent among the Mohammedan tribes of the Caucasus that
+keffir grains were, in the first instance, presented by Allah, as a sign
+of immortality, to one preferred tribe. Others hold that, in past ages,
+they were found by shepherds growing on a shrub in the Caucasian
+highlands; while, according to Skolotowski,[47] they were originally
+found adhering to the walls of an oaken vessel used for the preparation
+of airam. This is a soured milk beverage similar to keffir, but
+possessing a weaker alcoholic fermentation, and prepared from goats'
+milk by the addition of pieces of calf's stomach. This would undoubtedly
+serve to introduce various species of lactic acid bacteria, and will be
+referred to in the portion dealing with soured milks. Keffir is prepared
+by the Caucasians from cows', sheep's, or goats' milk, and the operation
+is carried on in large leathern tubes or bottles. After the addition of
+the grains or seeds to the milk the vessel is placed in a cool chamber,
+and the fermentation is allowed to proceed for one or two days, by the
+end of which time the normal fermentation is at an end. During this
+period the keffir grains have increased enormously in size, assume a
+bright yellow colour, and lose their sour buttery smell.
+
+Previous to the removal of the fermented liquid, a portion of the bottle
+is firmly bound from the rest by a stout cord, and the greater portion
+of the remaining keffir is quickly removed for use, thus avoiding, as
+far as practicable, any outside infection. After the addition of fresh
+warm milk the cord round the end of the bottle is removed, and the old
+and new milk thoroughly mixed for a time in order to ensure uniform
+inoculation of the new milk for the next fermentation. During the winter
+months the leathern vessels are often placed in the sunshine, so that
+the temperature remains at 61� to 65� F.
+
+The necessary agitation of the vessel is said to be supplied in the form
+of kicks by passers-by or by the children during their play.
+
+The beverage prepared in this way is so gaseous in character that it is
+often blown forcibly from the vessel during removal, and possesses,
+according to Podowyssozki,[48] a very acid taste.
+
+During any interruption in the preparation of keffir in the above
+manner, the grains are taken out, and after having been well washed in
+clean water, are spread out on a clean cloth to dry in the sunshine.
+They thereby assume a characteristic cheesy or buttery odour and become
+rather darker in colour. Thorough desiccation is essential in order to
+prevent subsequent mouldiness or disease of the grain.
+
+In European countries the grains are subjected to a preliminary soaking
+in water for five to six hours and then placed in four to five changes
+of milk, each change having a duration of two to three hours. As soon as
+the grains commence to rise to the surface of the milk, they may be used
+for the actual preparation. To this end, a small quantity of the grain
+is added to freshly boiled milk and allowed to stand for eight to twelve
+hours at a temperature of 55�-62� F. with agitation of the flask every
+two hours. By this time the milk, now known as Sakwaska, has become
+abundantly inoculated with the organisms essential to the fermentation,
+and after the removal of the grains, may be poured into well-corked
+flasks for the secondary brew. The flasks should be kept at a lower
+temperature for twenty-four to forty-eight hours, by which time the
+product is ready for consumption.
+
+According to the temperature and length of period to which this
+subsequent fermentation is allowed to proceed, the resultant keffir is
+more or less acid and gaseous. The grains may again be used for starting
+a fresh portion of milk, and a regular supply obtained in this manner.
+Well-fermented forty-eight-hours-old keffir should be an effervescent
+beverage with prickling and acid taste and a consistency and smell
+similar to sour cream. Large, persistent bubbles should form on the
+surface of the liquid and the casein be present as an extremely fine
+flocculent precipitate which remains suspended for a considerable time.
+
+From the third day there ensues a gradual peptonisation of the casein.
+If the temperature at which the secondary fermentation has occurred
+should be higher than 72� F., or if the milk has not been sufficiently
+agitated, then the casein will be present in the form of porous small
+flakes, which on shaking form a fine emulsion.
+
+The chemical changes undergone by the milk during the preparation of
+keffir are confined almost exclusively to the milk sugar. As already
+stated, a slight peptonisation occurs in old samples, but this depends
+very largely upon the method of preparation and purity of the culture.
+Hammersten[49] and Essaulow[50] show, however, that this is not a
+concomitant of normal fermentation. According to Hammersten, normal
+keffir contains--
+
+                            Per cent.
+  Water                       88.26
+  Fat                          3.35
+  Casein                       2.98
+  Lactalbumen                  0.28
+  Peptones                     0.05
+  Milk sugar                   2.78
+  Lactic acid                  0.81
+  Alcohol                      0.70
+  Ash                          0.79
+
+In no case should the acid be higher than 1.0 per cent., and the alcohol
+more than 0.75 per cent.
+
+_Biology of the Keffir Grain._--The first communication on the biology
+of the keffir grain seems to have been made by Kern.[51] He regarded the
+grain as a zo�gloea composed of bacilli and yeasts, the latter being
+regarded as the ordinary beer yeast (_Saccharomyces cerevisse�_), while
+to the former he gave the name of _Dispora caucasica_. As the name
+indicates, this bacillus possesses two polar spores, and germination of
+these proceeded in the same manner as with _Bac. subtilis_. As, however,
+pure cultures of the organisms were not made, and the descriptions and
+illustrations made by Kern fail to show any distinctive characteristics,
+it seems probable that accidental confusion with other organisms must
+have occurred.
+
+  [Illustration: A MILK FILLING APPARATUS
+
+  FIG. 10--Where soured milk is handled on the large scale,
+  a special filling apparatus for bottles is desirable, and
+  the soured milk supply should be under cover as shown.
+  This apparatus is made by the Dairy Machinery and
+  Construction Company.]
+
+Krannhals[52] succeeded in isolating ten different keffir bacteria among
+which were several sporulating bacteria. Here too it is impossible to
+attach any importance to the results, as the artificial preparation of
+keffir, by means of these bacteria, was not attempted. Beijerinck[53]
+studied the organisms constituting keffir grains and attached prime
+importance to the occurrence of two organisms, viz., (_a_) a yeast,
+_Saccharomyces kefir_, which was capable of inverting milk sugar by
+means of an enzyme (lactase) and afterwards fermented the products with
+the formation of alcohol and carbon dioxide, and also (_b_) a non-motile
+non-sporulating bacterium, afterwards _Lactobac. caucasicus_. The
+latter, when cultivated on gelatine, gave rise to tough warty colonies
+about 1/40 in. diameter, and was regarded as one of the lactic acid
+bacteria found in milk which has been incubated at 77� to 90� F. and
+afterwards incubated at a higher temperature, 100� to 104� F. Scholl[54]
+isolated three different organisms, of which a yeast inverted milk sugar
+for the lactic acid bacteria, while _Dispora_ peptonised the albuminoid
+matters.
+
+Adametz[55] failed to isolate _Dispora_, and came to the conclusion
+that ordinary lactic bacteria and yeasts played the most important part
+in the fermentation.
+
+Essaulow found in keffir grains six different organisms--yeast cells,
+cocci, short thick bacilli, bent bacilli, long threads, and motile
+bacteria. The two latter would seem to be _Bacillus subtilis_, while the
+others may be regarded as _Bacterium acidi lactici_ (Hueppe), _Bacterium
+a�rogenes_, and _Streptococcus lacticus_ (Grotenfeldt). Pure cultures
+were insufficient to produce keffir, while mixed cultures of _Bacterium
+acidi lactici_ and yeasts were effective.
+
+Freudenreich,[56] to whom we owe a record of very carefully executed
+experiments, could not arrive at a satisfactory explanation of the r�le
+of _Bacillus caucasicus_. This organism is described as being 5-6 � long
+and 1 � thick, slightly motile, and possessing bright refractive spots
+at the poles of the bacilli. It is extremely difficult to cultivate, and
+forms flat, small greyish colonies of irregular outline. The bright
+refractive spots above referred to are, however, granules taking the
+usual stains quite readily, and not spores as supposed by Kern.
+
+Freudenreich also found three other organisms--a yeast and two
+streptococci. The yeast, to which he gave the name _Saccharomyces_
+(Torula) _keffir_, forms small oval or roundish cells 2-3 � wide and 3-5
+� long. The optimum temperature would seem to be about 72� F.; the
+maximum 82� F. This organism is unable to ferment milk directly, but is
+able to decompose maltose and glucose with gas production. It does not
+coagulate milk, but imparts to it a characteristic taste and is unable
+to withstand desiccation for more than a few days.
+
+Of the two streptococci isolated, _Streptococcus a_ resembles organisms
+of the group _Streptococcus lacticus_ in appearance, but is able to
+ferment milk, with weak acid and gas production, and is capable of
+inducing coagulation.
+
+  [Illustration: FIG. 11.--Section through a Kephir
+  Grain--highly magnified.]
+
+Contrary to what one would expect in an organism existing in keffir
+grains, this streptococcus is as little able to withstand desiccation as
+the above-mentioned yeast. _Streptococcus b_ forms smaller cells as well
+as smaller colonies than _Streptococcus a_, but produces more lactic
+acid and more gas, and retains its vitality after desiccation. The
+relation of these four organisms is, according to E. von Freudenreich,
+as follows: _Sacch. keffir_ is unable to ferment directly milk or
+lactose, so that its growth must be preceded by that of _Streptococcus
+b_. _Streptococcus a_ does not seem to play this part, but, unlike
+_Streptococcus b_, is able to coagulate milk on its own account. By the
+combined action of the yeast and the two streptococci, then, milk can be
+coagulated, milk sugar inverted, acid and gas produced by the
+streptococci, while gas and alcohol are formed by the activity of the
+yeast. The r�le of _Bacillus caucasicus_ is unknown, but it would seem
+to play a part in the formation of the keffir grain itself. By means of
+mixed cultures of the above organisms Freudenreich was successful in
+obtaining a fermented product possessing in all respects the
+characteristic properties of normal keffir. On the other hand,
+experiments to induce the formation of keffir grains gave negative
+results, but in this respect the cultural characteristics of
+_Lactobacillus keffir_ would seem to give promise of success in the
+synthesis of the keffir grain. Fig. 11 is a photo-micrograph of an
+extremely thin section through a keffir grain, after a preceding
+treatment with saffranin. The matrix is composed entirely of long thin
+bacilli (_Bacillus caucasicus_), while the peripheral portions, which
+are more deeply stained, consist to a large extent of dense masses of
+yeast cells with occasional streptococci. In a normal grain the latter
+organisms are present on the surface or in the cavities and grooves of
+the grain, and only to a less extent in the matrix. Nikolaiewa[57]
+claimed to have isolated a hitherto unknown bacillus capable of
+coagulating milk by acid production, _Bacterium caucasicum_, not
+identical with, but related to Freudenreich's _Bacillus caucasicus_, and
+also a torula. Although no experiments were carried out, Nikolaiewa
+asserts that this organism forms the matrix of the grains. He was able
+to produce a beverage resembling keffir, just as Freudenreich and
+Essaulow did with entirely different organisms, but his product would
+appear to have been slightly too acid and to have lacked the
+characteristic aroma of the normal product. In the course of an
+extensive series of experiments Kuntze[58] found the following
+organisms:
+
+  (_a_) True lactic acid forming bacteria, _Streptococcus
+  acidi lactici_ (Grotenfeldt).
+
+  (_b_) Bacteria of the group _Bacterium acidi lactici_
+  (Hueppe) and _Bacterium lactis a�rogenes_.
+
+  (_c_) Various torula and yeast species.
+
+  (_d_) Two species of butyric acid bacteria, _Bacillus
+  esterificans_ and _Bacillus keffir_ (Kuntze).
+
+His conclusions are: 1. In any case the presence of a yeast capable of
+directly fermenting milk sugar is not essential. 2. The significance of
+the presence of yeast lies in the fact that stimulation of the lactic
+bacteria occurs; further, the yeast exerts a regulating influence upon
+the rapidity of the fermentation proper. The variety is of minor
+importance, provided always that the yeast does not produce an
+unpleasant flavour. By the use of mixed cultures of _Bacillus
+esterificans_, _Bacillus keffir_, and _Streptococcus acidi lactici_, and
+a keffir yeast, Kuntze obtained a product that possessed to the fullest
+degree all the characteristic properties of a normal keffir. In such
+cultures he was successful in obtaining the formation of keffir-like
+grains. Keffir fermentation is, according to Kuntze, the result of the
+action of various organisms. During the initial stage butyric acid
+fermentation takes place, but is prevented from becoming predominant by
+the action of the keffir yeast. Simultaneously a true lactic acid
+fermentation proceeds and eventually gives place to a subsequent
+secondary production of butyric acid. Finally, then, we have a certain
+amount of unison in the results obtained by Freudenreich, Essaulow,
+Nikolaiewa, and Kuntze. These show that, for the production of a
+characteristic keffir, specific organisms are not essential, provided
+always that those used possess, either individually or collectively, the
+essential capacity of acidifying, coagulating, and fermenting the milk.
+For the growth of normal grains the presence of a matrix-forming
+organism, such as _Bacillus keffir_, is indispensable.
+
+  [Illustration: FIG. 12--_Streptococcus lacticus_
+  (Grotenfeldt) growing on lactose-agar, stained by Gram's
+  method. ( X 900 diams.)]
+
+_Diseases of Keffir Grains._--According to the age and the previous
+treatment to which keffir grains have been subjected, the vitality of
+one or more of the organisms constituting the grain may have been
+impaired. The results of Freudenreich have shown that _Saccharomyces
+keffir_ and _Streptococcus a_ are unable to withstand desiccation for
+more than a few days, and this is sufficient to account for the frequent
+failures to obtain normal keffir from the grain. Further, grains succumb
+to a mucilaginous disease; the cavities become filled with a slimy
+fluid, and the grains are covered with mucilaginous matter. They lose
+their elasticity and become brittle or mealy, but large grains appear to
+be more subject to this fault than do the small ones. Such grains
+should be disinfected by immersion for a short time in two per cent.
+salicylic acid solution, followed by drying in the sun, whereby they are
+completely regenerated.
+
+Another disease consists in the predominance of certain butyric acid
+bacteria which impart an unpleasant rancid taste to the keffir
+(Podowyssozki). This is generally attributed to the use of rich milk, or
+too high a temperature during preparation.
+
+_Koumiss._--Another product of the combined action of lactic acid and
+alcohol-producing organisms is called koumiss, kumys, milk-wine, lac
+fermentation, or vinum lactis. In the steppes of Southern Russia and
+Asia, as we have seen,[59] it is prepared chiefly from mares' milk, but
+occasionally from that of camels and jennets. The name is said to be
+derived from that of a tribe mentioned by Xenophon and Pliny, viz., the
+Kumanen, by whom its preparation was practised. After the war with the
+Tartars in 1215 its use was adopted by the latter people, and eventually
+spread to the Turkomanen, Kalmucks, Khirgiz, Mongolians, etc.
+
+Rubruck, in 1253, records the use of a fermented drink--kosmos--prepared
+from mares' milk, and about the same time Marco Polo mentions the
+occurrence of a milk-wine, chumis or chemius, among the Tartars. The
+fact that the Tartars were seldom ill, and were almost invariably free
+from lung troubles, led to an influx of visitors from surrounding
+countries, until finally its use spread to Russia, Austria, and Germany.
+At the present time the best koumiss is that produced in the province of
+Orenburg; but specially equipped koumiss establishments, under the
+control of physicians, exist in Odessa, Samara, Ufa in the Urals, and
+other districts. The curative properties of koumiss have long been
+recognised and its use is indicated in cases of indigestion, chlorosis,
+scurvy, tuberculosis, etc.
+
+Rubinsky states that, among the nomadic tribe, of Khirgiz and Kalmucks,
+a special leathern bottle (Turssuk, Orroth, or Soaba) is used for the
+preparation of koumiss, while wooden tubs (Tschiljak) similar in shape
+to the old-fashioned churn are used by the Bashkirs, and in koumiss
+establishments.
+
+The fermentation is induced by the addition of koumiss to fresh mares'
+milk, in proportions which vary according to the cleanliness observed in
+the actual preparation. Where the process is carefully controlled, one
+part of koumiss to ten parts of milk is often used, but where gross
+infection from outside sources takes place one part of koumiss to three
+parts of milk is taken. The mixture is stirred at frequent intervals,
+and stored at a temperature of 73�-90� F. Weak koumiss is obtained after
+twenty to twenty-four hours in winter and twelve to fourteen hours in
+summer, but is scarcely ever consumed immediately, as it possesses a
+strong purgative action.
+
+It is generally poured into bottles (bottled koumiss); or allowed to
+remain in the tubs (tschiljak koumiss); in the former case the
+fermentation is ana�robic, in the second it is a�robic.
+
+Storage of the koumiss upon ice or in a cellar is necessary since medium
+koumiss is converted to strong koumiss in twelve to sixteen hours at
+ordinary temperatures, while at the lower temperature this occurs only
+in two to four days.[60]
+
+According to Biel,[61] either old koumiss or the dried sediment from old
+koumiss may be used for the initial inoculation. It may also be prepared
+by the repeated inoculation of mares' milk with soured cows' milk until
+a fermenting product is obtained. Koumiss may be prepared by a method
+stated by Allik[62] to be in general use in the Caucasian
+health-resorts. One part of beer-yeast is added to four to ten parts of
+fresh mares' milk (according to the strength of product required), and
+after thorough mixture of the two liquids the whole is allowed to
+ferment at a temperature of 70� to 72� F. for two days. One part of this
+first product is then added to five parts of fresh cold milk, and
+allowed to stand three to four hours at 75� to 77� F. It is then poured
+into bottles, and after the expiration of another three to four hours is
+stored away in a cellar at about 45� F. This koumiss may be used at any
+time from one to five days (generally two to three) after bottling
+according to the strength desired or prescribed in each individual case.
+
+The changes undergone during fermentation consist in a vigorous gas and
+acid production accompanied by alcohol formation and coagulation of the
+milk. The coagulum exists in an extremely fine state of division, and
+the liquid froths violently on the bottle being opened. It has a full
+pleasant acid taste, but should not contain more than one per cent. acid
+and two per cent. alcohol. The specific gravity of koumiss is 1.008 to
+1.020 at 60� F. Appended is an analysis of two different samples of
+koumiss:
+
+  ---------------------------------------------------
+                                 Prepared from
+  ---------------------------------------------------
+                          Mares' Milk.     Separated
+                                          Cows' Milk.
+  ---------------------------------------------------
+                           Per Cent.       Per Cent.
+  Water                     91.535          88.933
+  Fat                        1.274           0.854
+  Nitrogenous bodies         1.913           2.025
+  Sugar                      1.253           3.108
+  Ash                        0.293           0.444
+  Carbon dioxide             0.876           1.027
+  Alcohol                    1.850           2.647
+  Lactic acid                1.006           0.796
+  Glycerine                   ....           0.166
+  ---------------------------------------------------
+
+Fleischmann[63] gives a formula for preparing an artificial koumiss from
+separated cows' milk, water, cane sugar, and milk sugar, with the
+addition of distillery yeast. Needless to say, this product must possess
+some of the characteristic by-flavour of the yeast employed, and is less
+suitable than koumiss prepared by the aid of a lactic yeast. Schipin
+investigated the fermentation of koumiss and found three distinct
+organisms.
+
+Rubinsky in a recent article threw much light on the phenomena of
+koumiss fermentation. According to him, koumiss contains almost
+invariably four different organisms, viz., koumiss yeast, koumiss
+bacterium (_Lactobacillus_), _Streptococcus lactis_ (Lister), _Bacterium
+a�rogenes_, and occasionally _Bact. caucasicum_ (Nikolajewa). For the
+preparation of normal koumiss only the two former organisms are
+required; they exceed in number any of the other organisms whose
+presence in the dairy is unavoidable. The presence of the two latter
+organisms is favourable to the production of good koumiss, as, by
+inducing a preliminary lactic fermentation, they tend to inhibit the
+growth of undesirable extraneous bacteria, etc. In medium and strong
+koumiss they die out on account of the amount of lactic acid formed
+(1%).
+
+Koumiss yeast possesses strongly differentiated protoplasm, but lacks
+any cultural characteristics. Abundant growth occurs in milk, and lactic
+acid (0.3%), alcohol, carbon dioxide, albumens and peptones, volatile
+acids, and aromatic substances are formed.
+
+Koumiss bacterium is related to the _Lactobacillus_ of various other
+fermented milks, and is similar to _Bac. acidophilus_, and possesses
+like these a distinct polymorphism (branched cells, long and short
+bacilli, etc.). It is non-sporogenous, has an optimum temperature of 90�
+to 97� F., and possesses cultural characteristics similar to those of
+the rest of the _Lactobacilli_.
+
+The by-products of koumiss yeast appear to favour the growth of the
+koumiss bacterium, as this organism, like the other _Lactobacilli_, is
+favourably influenced by the presence of small quantities of peptone,
+alcohol, and acid.
+
+The organisms found by Schipin consisted of a species of _Saccharomyces_
+and two bacilli, _Bacillus acidi lactici_ and a non-sporulating
+bacillus. The latter organisms coagulate milk at 98� F., but not at room
+temperature, and although a minute description of cultural
+characteristics is not given it would seem to be related to _Bacillus_
+or _Lactobacillus caucasicus_.
+
+_Leben Ra�b_ or _Leben_ (_Laban._)--This is a beverage prepared largely
+by the Egyptians, and differs from keffir, as does matzoon, in
+possessing a characteristic aroma and taste. It differs also from the
+former by having only a very weak alcoholic fermentation, and by the
+coagulum being coarse and lumpy instead of being extremely fine. It is
+made from buffaloes', goats', or cows' milk by the addition of roba (or
+old leben) to the previously boiled and cooled fresh milk. The use of
+leben is many centuries old, and it is used in Egypt as in Arabia for
+medicinal purposes, although that of the Syrians and Arabians is said to
+differ from that of the Egyptians and Algerians. The fermentative
+changes occurring in the formation of the Egyptian leben have been
+investigated by Rist and Khoury,[64] and also by Guerbet,[65] who found
+that five organisms were normally present. These comprised a
+chain-forming bacillus (_Streptobacillus_), a second smaller bacillus
+(_Bacillus lebenis_), a diplococcus, a saccharomyces, and a mycoderma.
+Of these five organisms, it would appear that four live in metabiosis,
+the streptobacilli and bacilli hydrolyse the milk sugar, the components
+of which are split up by the yeast to alcohol and carbon-dioxide. The
+alcohol thus formed, together with the glucose formed by hydrolysis, are
+eventually converted to acid or combusted by the mycoderma species. The
+leben thereby assumes the sharp, unpleasant flavour met with in old
+samples. The diplococcus merely produces acidification and coagulation
+of the milk. Rist and Khoury were able, by the use of these organisms,
+to produce normal leben, especially when the true yeast was allowed to
+grow in the milk for some time before inoculation with the other
+organisms was made.
+
+Some of the half-civilised tribes of Siberia, the Tartars and the
+Burgaten, prepare a strong alcoholic beverage, arak� or ojr�n, from
+fermented milk. This is really a product of distillation, and contains
+seven to eight per cent. of alcohol and volatile fatty acids.
+
+  [Illustration: FIG. 13--Photo-micrograph of preparation
+  from Armenian soured milk (Matzoon). This is related to
+  Yoghourt, and contains, as will be seen from the above
+  photo, yeasts, streptococci, diplococci, and a bacillus
+  with the morphology of _Bacillus bulgaricus._ This, and
+  similar foods, owe their peculiar properties primarily to
+  the presence of _Bacillus bulgaricus_ (type A, White and
+  Avery), and only in a lesser degree to the yeasts and
+  lactic streptococci.]
+
+_Matzoon._--This is a drink used largely in Western Asia, and is similar
+in character to keffir, but has a peculiar taste which distinguishes it
+from all other fermented milks. According to Weigmann,[66] it is
+prepared from buffaloes', goats', or cows' milk, and is used partly as a
+means of souring milk for butter-making and also as a lactic food, eaten
+with spoons. In the same way buttermilk produced from milk which has
+been previously ripened by matzoon is used as a beverage. Finally, the
+coagulum (_than_) of such buttermilk is strained off, and, after being
+pressed, is mixed with meal and dried by exposure to the sun's rays. The
+preparation of matzoon is in many respects very similar to that of
+keffir and koumiss, but differs by inducing a comparatively weak alcohol
+fermentation. In common, too, with yoghourt, the prevailing temperature
+is much higher than is required for keffir and koumiss.
+
+In regard to the biology of matzoon, the occurrence of various organisms
+has been recorded. Emmerling[67] isolated, in addition to a yellow
+pigment-forming organism, _Bacillus subtilis_, _Bacillus lactis acidi_,
+and several fungi, a small micrococcus capable of hydrolysing milk- and
+cane-sugar. The organism produces and without gas formation, or
+peptonisation of the medium. Of the nine yeasts isolated from matzoon by
+Lindner[68] and Kalantharianz,[69] three were able to ferment milk sugar
+without previous hydrolysis, while two others, by the simultaneous
+production of lactic acid and fruit esters, gave to the matzoon its
+characteristic taste and aroma.
+
+_Yoghourt and Soured Milk._--Yoghourt is another fermented milk, and is
+related to the matzoon of Armenia, the gioddu of Sardinia, and the leben
+of Egypt. After a preceding boiling and reduction of the volume of the
+milk, inoculation of the mass is made by the addition of a small
+quantity of old culture, and it is then allowed to sour at a
+comparatively high temperature. A moderately compact, jelly-like
+coagulum is thus formed, while keffir and koumiss possess a liquid
+consistency. The fermentation necessary for the two latter products only
+proceeds, too, at a much lower temperature, at which yeasts play an
+important part. According to Guerbet, yoghourt incubated for ten hours
+at 113� F. contained 0.34 per cent. lactic acid and 0.012 per cent.
+alcohol. Luerssen and K�hn[70] came to the conclusion that yoghourt
+contained chiefly a mixture of _Bacillus bulgaricus_, diplostreptococci,
+and a "granule" bacillus, so called on account of its granulated
+appearance after treatment with methylene blue. According to these
+authors, the first two organisms were found in each of eight samples of
+maya (young yoghourt) and of yoghourt itself, but the occurrence of the
+"granule" bacillus in plate cultures was by no means regular. In
+addition, yeasts were found in almost every sample examined, but were
+regarded more as accidental infections rather than as essential to the
+formation of a typical product. The combined action of the three
+organisms already mentioned gave rise to a product closely resembling
+normal yoghourt. Piorkowski[71] subjected Bulgarian maya to examination
+and associated himself with Metchnikoff[72] in finding three species, a
+streptococcus, a diplococcus, and a specific organism to which he gave
+the name _Yoghourt bacillus_. Similar results were also obtained by
+Grigoroff.[73] Piorkowski's _Yoghourt bacillus_ is similar in form to
+_Bacillus subtilis_, but does not sporulate, nor does it liquefy
+gelatine. Young individuals are stained by Gram's method; older
+individuals are, however, Gram negative. The optimum temperature is 112�
+F. Kuntze attempted to isolate the organisms mentioned by Luerssen and
+K�hn, and by plate culture procured growth of a spore-forming bacillus
+similar to Weigmann's _Bacillus matzoon_. To this organism is attributed
+the power to impart a specific taste to the matzoon, but as growth is
+comparatively slow, it can only be of significance in determining the
+quality of the curd and cheese prepared from this product. Cultures were
+also obtained which resembled in general character those of the organism
+described by Luerssen and K�hn as _Bacillus bulgaricus_ and named by
+Kuntze _Bacterium W_. Granule formation was transient in this culture,
+and the organisms eventually became inactive. Further analysis of maya
+gave cultures of the "granule" bacillus, but these passed over from the
+type forming irregular colonies (see Figs. 14, 15, 16) to that producing
+smooth colonies. Further, although the granule formation persists
+largely in milk, the organisms soon revert to the non-granular type if
+cultivated on agar. By the use of the Gram-Weigert stain organisms from
+a several-days-old culture on beer-wort-agar gave an interesting
+reaction. The bacillar threads are in places Gram-negative, in others
+Gram-positive, and bear small club-like swellings (see Fig. 14). Results
+similar to these were also obtained with cultures of _Bacillus matzoon_
+(Weigmann and Gr�bner) and also with _Bacillus acidophilus_.
+
+Neisser's method of staining failed to give such good effects by the
+examination of fresh maya, as did an alcoholic aqueous solution of
+methylene blue in showing up the granules of the organisms. Again,
+Grixoni[74] found, but did not isolate, a similar granule-forming
+organism (_Bacterium sardous_) in Sardinian gioddu. As already
+mentioned in the description of leben, Rist and Khoury found a long
+bacillar lactic ferment (_Streptobacillus lebenis_) which also exhibited
+the irregular greyish white hairy colonies and high optimum temperature
+characteristic of this group. On account of the similarity in form,
+staining reactions, temperature requirements, and cultural growth of the
+organisms described by Emmerling, D�ggeli, Weigmann, Grixoni, and Rist
+and Khoury, Kuntze is inclined to regard them as belonging to one single
+group of lactic ferments. According to him the granule formation is
+rather variable, and may be induced or suppressed by cultural methods.
+Not only do organisms of this group produce far more acid than the
+normal lactic bacteria; they are also more resistant to acid, and are
+able to develop in milk to which 0.5 per cent. hydrochloric acid has
+been added. A comparatively high percentage of alcohol seems to
+encourage growth, and this was obtained in milk containing 4 per cent.
+alcohol. This would no doubt tend to explain the phenomenon observed by
+Kuntze that milk is not so rapidly fermented by organisms of this group
+as when cultures of diplococci and yeasts are added. Since organisms of
+this group would seem to be widely distributed, the question of their
+natural habitat arises. Luerssen and K�hn were unsuccessful in their
+search for such organisms in K�nigsberg milk, but Leichmann records the
+occurrence of a long bacillus (_Bacillus lactis acidi_) in milk that had
+spontaneously soured at 112� to 120� F. This organism, too, showed
+characteristic growth on agar media, and produces l�vo-rotatory lactic
+acid. The examination of calves' stomachs showed, according to Kuntze,
+only occasional long bacilli, but inoculation of sterile milk and
+incubation at 100� F. with repeated over-inoculation gave a culture
+showing the characteristic granule reaction (see Figs. 18 and 20).
+Although plate cultures made direct from calves' stomachs do not exhibit
+the regular contours generally shown by the granule bacillus, yet this
+growth may be induced by preceding cultivation in lactose bouillon to
+which 0.5 per cent. acetic acid has been added. A similar organism,
+_Bacillus acidophilus_, was isolated from calves' manure by means of
+this acetic bouillon, as was also a diplostreptococcus which resembled
+very closely the typical lactic acid streptococcus. This resemblance was
+made all the more striking by the fact that they were capable of
+coagulating milk at a temperature of 99� to 104� F. Since these
+organisms are present in large numbers in manure and also in the
+digestive tract of ruminants, it would seem probable that their
+occurrence is not without significance for the operations of cheese
+manufacture. According to Jensen, the practice of applying farmyard
+manure to Swiss meadows has been regarded as absolutely essential to the
+production of cheese of the best quality; while, on the other hand, the
+application of artificial manures would seem to have been responsible
+for an increase in abnormal cheese. Kuntze found further that by the
+combined inoculation of sterile milk with the diplostreptococcus and the
+"granule" bacillus from calves' stomachs, together with a yoghourt
+yeast, he was able to obtain a product possessing a taste and aroma
+little different from normal yoghourt. During their investigations upon
+the ripening of Swiss hard cheese, Freudenreich and Jensen[75] isolated
+five varieties of lactic acid bacilli, and were able to show that one of
+these, especially _Bacillus casei [Greek: e]_, was of the greatest
+importance for the production of good cheese. This organism has been
+found by Th�ni to be present in rennet tablets, while a related
+variety, _Bacillus casei [Greek: d]_, was found in fresh calves'
+stomachs. Unfortunately, staining tests with these organisms were not
+carried out, so that no data are available in regard to the presence of
+granules. The photo-micrographs of these organisms show the small clubs
+and true-branched forms. The presence of these diplococci and bacillar
+lactic ferments in the intestinal tract of ruminants and horses might
+possess some importance for the preparation of yoghourt in bags or tubes
+made from the stomachs of these animals. Finally, Moro[76] has isolated
+an acidophilic organism from the dejecta of infants which resembles
+closely, both in manner of growth, resistance to acids, true branching,
+and temperature optimum, the granule bacillus and related forms.
+
+[This group of sixteen illustrations (Figs. 14 to 29), showing various
+aspects of the Yoghourt bacillus and others of a cognate nature, is
+taken from the _Centralblatt f�r Bakteriologie_ of Jena.--L. M. D.]
+
+  [Illustration: FIG. 14.--Granule Bacillus from Yoghourt.
+  Shredded preparation of a fresh skim-milk culture at 37�
+  C. for six hours. Stain: aqueous methylene blue. (Enlarged
+  1:500.) In Figs. 15 and 17 will be noticed the chain
+  arrangement of the bacillus, which, in spite of the
+  supposed data of Luerssen and Kuhn, will be generally
+  noticed in the granule bacillus.]
+
+  [Illustration: FIG. 15.--Granule Bacillus from Yoghourt,
+  cultivated after the usual Agar method, for twenty-four
+  hours at 37� C. Stain: aqueous methylene blue. (Enlarged
+  1:500.)]
+
+  [Illustration: FIG. 16.--Granule Bacillus from Yoghourt.
+  Agar Milk Sugar Culture cultivated for forty-eight hours
+  at 37� C. Below is the true branching, above, the
+  distorted involution form. This production of involution
+  forms occurs chiefly in old cultures, and is an indication
+  of degeneration. Stain: aqueous methylene blue. (Enlarged
+  1:700.)]
+
+  [Illustration: FIG. 17.--_Bacteria W._ from Milk,
+  cultivated twenty-four hours at 37� C. Methylene blue.
+  (Enlarged 1:500.) The similarity in the pictures ought to
+  serve as a proof of the near relation of the granule form
+  and non-granule varieties.]
+
+  [Illustration: FIG. 18.--Agar Milk Sugar Culture. From the
+  original Bulgarian Yoghourt. In the centre, and beneath,
+  the characteristic hairy irregular colonies of the granule
+  bacillus (_Bacillus bulgaricus_ group), to the left, the
+  smooth contoured yeast colonies. The colonies of the
+  former organism always remain microscopic in size.
+  (Incubated several days at 20� to 25� C. Magnified X 10.)]
+
+  [Illustration: FIG. 19.--Agar Milk Sugar Culture. Surface
+  colony of granule bacillus from calf's stomach. The great
+  resemblance this colony bears to those formed by the
+  granule bacillus from Yoghourt will be apparent. This
+  fact, as well as close agreement in other cultured
+  features, induced Kuntze to place these organisms in one
+  group. (Incubated two days at 37� C. Magnified X 100.)]
+
+  [Illustration: FIG. 20.--Agar Milk Sugar Culture.
+  Deep-lying colony of granule bacillus from calf's stomach.
+  The form of the colony is often determined by the relative
+  presence or absence of air. (Two days at 37� C. Enlarged
+  about 1:50.)]
+
+  [Illustration: FIG. 21.--Agar Milk Sugar. Colony of
+  _Bacterium W._ from Yoghourt (non-granular variety of the
+  granule bacteria, as far as possible identical with
+  Luersen and K�hn's _Bacillus bulgaricus_), of a cubical
+  branching-out form.
+
+  According to Kuntze, the granule formation of this and
+  related organisms is variable, while White and Avery
+  regard it as a constant characteristic. (Incubated two
+  days at 37� C. Magnified x 50.)]
+
+  [Illustration: FIG. 22.--Two colonies of _Bacillus
+  acidophilus_ from calf's manure. Agar Milk Sugar Culture.
+  With this organism, also, we have conformation to one type
+  of colony, while, in other respects, temperature
+  requirements and production, etc., we have close agreement
+  with the granule bacillus (_Bacillus bulgaricus_). (Two
+  days at 37� C. Enlarged about 1:50.)]
+
+  [Illustration: FIG. 23.--Beer-wort Gelatine.
+  Fourteen-days-old colony of Yoghourt yeast. (Enlarged
+  about 1:50.)]
+
+  [Illustration: FIG. 24.--Shredded preparation of the
+  Bulgarian original Yoghourt. Stain: aqueous methylene
+  blue. Granule bacillus, diplostreptococci, and yeast. (See
+  also other photo-micrographs of Yoghourt. Enlarged
+  1:70.)]
+
+  [Illustration: FIG. 25.--Granule Bacillus from Yoghourt.
+  Cultivated in skim milk in twenty-four hours at 37� C.
+  Stain: aqueous methylene blue. (Enlarged 1:50.)
+
+  By means of this staining treatment the presence of
+  granules (not spores) can be easily detected. Treatment
+  with fuchsine fails to bring out these formations.]
+
+  [Illustration: FIG. 26.--_Bacteria W._, Agar Milk Sugar
+  Culture. Cultivated twenty-four hours (knobs, clubs).
+  Stain: Gram's method coloured with aqueous fuchsine
+  afterwards. (Enlarged 1:600.)]
+
+  [Illustration: FIG. 27.--_Bacteria acidophilus_ from
+  calves' manure, isolated by means of bouillon as acid as
+  vinegar. Shredded out of the usual Agar culture.
+  Twenty-four hours at 37� C. Stain: aqueous methylene blue.
+  (Enlarged 1:700.)]
+
+  [Illustration: FIG. 28.--Mucus from calf's stomach
+  inoculated into milk after eight transferrings. Shredded
+  preparation cultivated in milk for twenty-four hours at
+  37� C. Diplostreptococci and granule bacillus. Stain:
+  aqueous methylene blue. (Enlarged 1:500.)]
+
+  [Illustration: FIG. 29.--Diplostreptococcus from Yoghourt.
+  Pure culture in skim milk. A comparison of the
+  illustrations will show how close a resemblance exists
+  between bacteria found in the mucous membrane of calf's
+  stomach and those occurring in Yoghourt. In fact, by the
+  combined action of granule bacilli, and of
+  diplostreptococci from calf's stomach, together with a
+  Yoghourt yeast, it is possible to prepare normal
+  Yoghourt.]
+
+In a review of the literature of the subject of soured milks, Makrinoff
+suggests the adoption of the two names, _Streptobac. lebenis viscosus_
+and _Streptobac. lebenis non-viscosus_, for the organisms of the
+so-called Bulgaricus group, and known at present as
+_Bacillus-bulgaricus_, _Streptobac. lebenis_, _Bacillus of Massol_,
+_Granule bacillus_, _Bact. Mazun_, _Bac. lactis acidi_, etc.[77]
+
+White and Avery[78] have made a comparative study of a large number of
+varieties and species of lactic acid bacteria of the above type obtained
+from various fermented milks and milk tabloids. Their descriptions are
+so detailed and their conclusions are so important that we give them at
+length. According to this work, the whole of the thermophilic lactic
+acid bacilli of the so-called Bulgaricus type may be divided into two
+sub-types, A and B.
+
+
+_The Cultural Characteristics of the Bacillus Bulgaricus Group_
+
+The cultural characteristics of all the strains of _Bacillus bulgaricus_
+(granule bacillus) are as follows:
+
+_In Whey Agar._--All strains exhibit wide variation in size, 2 � to 50 �
+long and about 1 � broad.
+
+Almost all individuals are intensely Gram-positive, and show regularity
+of outline. All strains show involution form, exhibiting vacuoles, and
+often show empty cell membranes. The latter are Gram-negative, and vary
+greatly in both dimensions as well as in form. All strains show tendency
+to chain formation, some being arranged in chains of six to twenty-five
+segments, which may contain both Gram-positive and Gram-negative
+individuals. Type B exhibits Gram-negative spherical bodies varying from
+0.25 � to 1 � in size, adhering to the sides of some of the
+Gram-negative individuals.
+
+_In Whey._--In this medium there is a marked tendency toward
+degeneration and involution. In the early stages of incubation, at 100�
+to 112� F., the bacilli are uniform in size and intensely Gram-positive;
+in succeeding stages the irregular, vacuolated, inflated, and ruptured
+forms predominate. Between the eighteenth and twenty-fourth hours of
+incubation at 112� F. the strains of type A develop oval to
+kidney-shaped nodules attached to a stem extending from the cell
+substance. As the incubation is prolonged these nodules increase in
+size, often measuring 1 � to 2 � in length; this nodule formation occurs
+at the expense of the cell protoplasm, and appears to be a marked
+characteristic of growth in whey. Cultures of type B do not form nodules
+or clubs, but small spherical bodies more or less securely attached to
+the cell wall are seen. Again, type A assumes the form of small bacilli
+in chains, while type B strains develop to a greater length and exist
+almost exclusively as single isolated forms. True branching has been
+observed in strains of type B.
+
+_In Milk._--In milk there is a tendency to thread-formation consisting
+of four to ten segments in the case of type A, while type B shows longer
+and more curved forms. With increasing age of the culture there also
+appears to be increase in the length of the organisms. All strains are
+non-motile, non-sporogenous, and non-capsule-forming.
+
+_Staining Reactions._--All strains are readily stained by the usual
+aniline dyes.
+
+_A. Gram's Method._--Young individuals give an intense reaction with
+this stain; old bacilli are easily decolourised, and degenerate forms
+are always Gram-negative, while single individuals have been observed
+which showed gradation from one pole of the cell to the other.
+
+_B. Loeffler's Methylene Blue._--According to the behaviour of the
+organisms studied, a separation into two types appears possible, type A
+being uniformly impregnated, while type B shows distinct
+differentiation. The cell body is seen to contain a varying number of
+round to oval bodies or granules. This is the appearance already
+mentioned by D�ggeli, Luerssen and K�hn, and Kuntze, and from which the
+granule bacillus derives its name. In opposition to the observations of
+Kuntze, the occurrence of granules was not found to be variable; it was,
+indeed, so constant as to constitute a distinguishing characteristic
+between the two types. The organisms of this group are difficult to
+cultivate, and freshly isolated growth is obtainable only on media
+containing whey, malt, or in milk. They grow equally well under a�robic
+or ana�robic conditions. The optimum temperature for growth is 113� to
+115� F.; growth is fair at 85� F., slight at 75� F., and does not take
+place at 68� F.
+
+Colonies on whey agar are round to irregular, greyish white, curled and
+filamentous, often streaming, and in a few cases smooth and even in
+structure. Gelatine is not liquefied. There is no surface growth on
+gelatine stab-cultures. Along the stab the growth is filiform, beaded,
+with subsequent horizontally projecting ramifications. Milk is
+coagulated in eight to eighteen hours at 112� F., and is the most
+favourable medium for growth.
+
+[I am indebted for this group of illustrations (seventeen in number) to
+the editor of _Bacteriotherapy,_ New York, U.S.A.--L.M.D.]
+
+  [Illustration: FIG. 30--Photo micrograph of preparation
+  made from Yoghourt, showing yeast cells, large lactic
+  diplococci, small slender bacilli and many large bacilli
+  possessing the morphology of _Bacillus bulgaricus_. Yeast
+  cells are almost invariably found in native Yoghourt, but
+  do not appear to be essential to the production of a
+  tropical beverage. Indeed, they would seem to be
+  responsible for the unpleasant astringent taste often met
+  with in old samples of this product.]
+
+  [Illustration: FIG. 31--Photo micrograph of smear from
+  Greek Curdled Milk called "Giaourti," and showing yeast
+  cells, long bacilli and a mould (_Oidium lactis_),
+  possessing very large elongate cells. The presence of the
+  latter is very undesirable, as it rapidly combusts the
+  lactic acid, digests the casein, and imparts a strong
+  unpleasant cheesy flavour to the beverage.]
+
+Type A produces 2.7 per cent. to 3.7 per cent. inactive lactic acid in
+milk, while type B produces only 1.2 per cent. to 1.6 per cent.
+l�vo-rotatory lactic acid in milk. There is a small quantity of acetic,
+formic, and succinic acids formed. The conclusions of White and Avery
+are:
+
+I. A review of the morphological culture and biochemical features of the
+lactic acid producing bacilli from yoghourt, matzoon, and leben, appears
+to justify their classification as a single group.
+
+II. This group would seem to be identical with _Bacterium caucasicum_
+(Kern).
+
+III. The significant variations exhibited by these bacilli in regard to
+the presence or absence of granules demonstrable by differential stains,
+the degree of lactic acid production, and the nature of the acid
+produced, suggest a division into two different types--the true type A,
+and the paratype B.
+
+Quite recently Hastings and Hammer[79] recorded the isolation from milk
+of an organism producing more acid than either _Bacterium coli commune_
+or _Bacillus lactis acidi_. It is characterised by possessing a high
+optimum temperature, and by the limited conditions under which it grows
+on nutrient media. On this account these investigators suppose it to be
+related to those described in the paragraphs on fermented milks, leben,
+matzoon, etc., and which are regarded by Kuntze as being identical.
+
+Similarly Boutroux[80] found 1.5 per cent. acidity produced in a
+solution containing albuminous matter and glucose; while Richet[81]
+states that with the addition of gastric juice to milk as much as four
+per cent. acidity may be formed. After storing samples of milk for eight
+days at 100� F., Koning[82] found 2.35 per cent. and 2.5 acid; while
+similar samples stored at 60� to 62� F. for the same period only
+developed 0.9 per cent. Heinemann[83] records the production of 3.0 per
+cent. acid in milk incubated at 100� F.; and Jensen states that
+_Bacillus casei [Greek: e]_ is capable of developing 2.7 per cent.
+lactic acid.
+
+Dr. H. B. Hutchinson, bacteriologist at Rothamsted Experimental Station,
+has also been successful in isolating a bacillus from English market
+milk resembling in every particular those classified by White and Avery
+as type A.
+
+  [Illustration: FIG. 32 is a photo-micrograph of soured
+  milk inoculated with a tablet containing viable and pure
+  cultures of _Bacillus bulgaricus_, and incubated for
+  seventy-two hours. These tablets constitute a valuable
+  means of preparing soured milk for therapeutic purposes.]
+
+  [Illustration: FIG. 33 is a photo-micrograph of milk
+  inoculated with a ferment tablet in which _Bacillus
+  bulgaricus_ is no longer viable, and the only growth
+  obtained is that of an organism allied to the _Bacillus
+  subtilis_ (Hay bacillus) group. Such milk would be
+  absolutely without value.]
+
+It will thus be seen that organisms related to those of Oriental and
+Occidental milk beverages are present in conditions where it is
+impossible for them to attain to any active growth. The same class of
+organism has also been found in many cases in butter and cheese
+throughout the United States.
+
+Of recent years the consumption of milk fermented by these organisms has
+been introduced more or less successfully into all European countries.
+This custom is due, as we have seen,[84] to a very great extent to the
+announcement of Metchnikoff[85] that the action of such organisms in the
+alimentary tract conduce to a prolongation of life. Moro found that the
+dejecta of children contain large numbers of _Bac. lacidophilus_ and
+_Bac. bifidus_, but, as age advances, the bacterial flora of the
+intestines tends to change. The number of acid-producing organisms
+gradually becomes less, and other bacteria capable of producing
+far-reaching decomposition of albuminoid matter tend to increase.
+
+Working on the assumption that senility is partially due to the
+absorption of by-products formed from albuminoid food by the
+decomposing or putrefactive bacteria mentioned, Metchnikoff instituted a
+search for organisms capable of suppressing the growth of the
+putrefactive bacteria.
+
+It has long been known that milk allowed to become sour will keep for a
+considerably longer period in hot weather than if lactic bacteria had
+not grown. This preservative action of lactic acid also comes into play
+in the manufacture of sauerkraut and in the preservation of meat by
+immersion in sour milk.
+
+  [Illustration: FIG. 34.--Photo-micrograph of smear of
+  culture of _Bacillus bulgaricus_, recommended by
+  Metchnikoff for use in cases of intestinal
+  auto-intoxication. Unlike the ferments of normally soured
+  milk, which are sometimes indifferent, or even injurious,
+  in their action, this bacillus is capable of growth at
+  blood heat, and, by producing much larger quantities of
+  lactic acid than such organisms as _Streptococcus
+  lacticus_, _Bacillus coli commune_, or _Bacteria lacticus
+  a�rogenes_, inhibits the multiplication of bacteria
+  responsible for the putrefaction of albuminoid food in the
+  intestines.]
+
+Bienstock has shown that the growth of _Bac. putrificus_ is inhibited by
+the action of _Bact. coli commune_, which is capable of setting up a
+slight lactic acid fermentation. _Bact. coli commune_, however, gives
+rise to substances of an injurious character, and, although present very
+abundantly in the intestinal tract, it may by reduced almost entirely by
+the active growth of lactic acid bacteria. This fact is of great value
+to the cheese-maker, since by the addition of a lactic acid culture
+(starter) to milk before renneting, gas-producing bacteria such as
+_Bact. coli_ may be checked in growth. Since the ordinary lactic acid
+bacteria such as _Streptococcus lacticus_, _Bac. lactis acidi_, and
+others, are incapable of growth at blood temperature, it appeared
+necessary to procure cultures of lactic bacteria able to grow at
+temperatures of 100� F. to 112� F. Such an organism was found in
+Bulgarian soured milk (yoghourt), and was considered pre-eminently
+adapted to this purpose. As has been shown in the preceding paragraphs,
+this organism is merely one of a large group of bacteria found
+distributed in the intestinal canal of many domestic animals, in manure,
+and in ordinary market milk. It is then not surprising that the
+introduction into the intestinal tract of bacteria of the type
+_Bulgaricus_ in the form of tabloids has not met with any decided
+success. Although it was considered to be merely necessary to introduce
+the desired type of organism into the body, and the amount of lactic
+acid taken into the system by the administration of soured milks was
+looked upon as of secondary importance, yet, it would seem, in the light
+of recent investigations, that benefits derived from a soured milk
+regimen are attributable in part to a chemical as well as a purely
+bacterial action. This receives support from the fact that soured milk
+beverages prepared by the use of ordinary lactic bacteria, distinct from
+those of the _Bulgaricus_ type, often exert a beneficial influence upon
+human beings even although the organisms responsible for the
+fermentation are incapable of growth at blood temperature.
+
+It may be mentioned in conclusion that cultures prepared by the use of
+organisms of the type _Streptococcus lacticus_ combined with _Bac.
+bulgaricus_ possess a more agreeable flavour and aroma than those
+prepared from a pure culture of _Bulgaricus_ alone.
+
+  [Illustration: FIG. 35--_Bacillus bulgaricus_, showing the
+  cultures in English cow's milk. (Magnified 450 diams.)]
+
+  [Illustration: FIG. 36--Photo-micrograph of pure culture
+  of _Bacillus bulgaricus_. The administration of cultures
+  of this organism is indicated in all cases of intestinal
+  ailments, caused by the excessive growth of proteolytic
+  bacteria, and consequent putrefaction of foods in the
+  alimentary tract. By the formation of large quantities of
+  lactic acid, a state of asepsis is ensured, which is
+  particularly valuable in cases of operations on the
+  abdomen and intestines.]
+
+  [Illustration: FIG. 37.--Photo-micrograph of smear of
+  combined culture of _Bacillus bulgaricus_ and _Bacteria
+  paralacticus_. This double culture possesses an advantage
+  over single cultures in that, while the characteristic
+  disinfecting action of the former is retained, any
+  secondary action of the growth of this organism upon the
+  milk-fat is checked by the growth of _Bacillus
+  paralacticus_, thus ensuring the production of a more
+  palatable product.]
+
+
+
+
+CHAPTER VI
+
+THE PREPARATION OF SOURED MILK IN THE HOUSE
+
+
+There is no great difficulty in making soured milk at home: the
+necessary operations are quite simple, but at the same time they must be
+conducted with precision and care, otherwise the results may be
+unsatisfactory and disagreeable; there may even sometimes be danger in
+badly prepared sour milk. It is always an advantage in such matters to
+understand the reason of things, and a few notes on the surrounding
+conditions, and what has to be accomplished, may be of assistance to the
+would-be experimenter.
+
+The majority of intelligent people are now acquainted with the fact that
+the germs of bacteria are to be found everywhere on the surface of the
+earth, in air, and in water, and that they are the sole cause of the
+decay of all manner of perishable articles.
+
+The distribution is unequal--bacteria are much more plentiful where
+there is decaying matter--in dirty houses, sewage, or other contaminated
+water, etc. Milk is a splendid food for bacteria, and numerous varieties
+multiply in it exceedingly, and many of these are injurious, producing
+putrefactive changes which render the milk unwholesome, even poisonous
+in some cases. Others are beneficial, and are absolutely necessary for
+the souring of milk for making butter or cheese and for the ripening of
+the latter. The soured milk which is the subject of this book is the
+work of certain lactic-acid-producing bacteria, and the problem we have
+before us is to encourage the growth of the latter to the uttermost and
+to exclude the others.
+
+As bacterial germs are present in the air and readily sow themselves
+into any medium with which they come in contact, the first consideration
+is to get good fresh milk which has been as little exposed to the air as
+possible. The second is to conduct the experiment where the germs are
+fewest, and in cleanly surroundings, far removed from decaying matter
+and free from taints and smells.
+
+  [Illustration: FIG. 38.--Photo-micrograph of smear of
+  one-month culture of _Bacillus bulgaricus_. In spite of
+  its age, the culture is perfectly free from any foreign
+  organisms, which would otherwise lower its value for the
+  preparation of soured milk, and might, indeed, make it
+  directly injurious.]
+
+  [Illustration: FIG. 39.--Photo-micrograph of culture of
+  _Bacillus bulgaricus_ in malt. In cases of acute
+  enteritis, where milk cannot be supported, the lactic
+  bacilli may be cultivated in malt, and administered to the
+  patient in this form, with occasional doses of syrup of
+  malt, in order to induce a vigorous growth of the lactic
+  ferments in the body.]
+
+  [Illustration: FIG. 40.--Photo-micrograph of smear from
+  milk that had been allowed to sour spontaneously. Ordinary
+  market milk is always subject to infection from the air,
+  milking vessels, manure, etc., and from these sources a
+  mixed bacterial flora arises, with the result that the
+  milk exhibits curdling, acidity, gaseous fermentation, or
+  mould growth, after being stored for a short time. This is
+  due to the action of sush bacilli, diplococci, yeasts, and
+  moulds as are shown in this illustration.]
+
+However fresh the milk may be, it will contain useless or injurious
+bacteria, and we must get rid of these before attempting to introduce
+those whose growth we wish to encourage. This is effected by heat. All
+the living bacteria and most of the germs are killed at temperatures
+somewhat under the boiling point. Having sterilised the milk in this
+way, it is necessary, as far as possible, to prevent the entrance of
+fresh germs from the atmosphere, and we therefore let the milk cool down
+in covered dishes. When the temperature descends to about 100� F. the
+culture of the special bacteria is introduced, the covers are replaced,
+and the milk vessels maintained at or near this temperature for twelve
+hours, when the soured milk is ready for use. It is not necessary to use
+fresh culture every time--a little of the soured milk will take its
+place, and this may be repeated as many as fourteen times before it is
+necessary to start off again with a fresh culture. A great deal depends
+on the care exercised and the freedom of the surroundings from bacterial
+germs. Under the best conditions wild germs will gradually accumulate in
+the soured milk, but their increase may be greatly delayed by attention
+to the precautions mentioned. The ordinary souring of milk for butter
+and cheese making is conducted in cool surroundings, as already stated,
+because in such conditions the lactic-acid-producing germs increase
+relatively faster than the wild germs, and so gain the upper hand, but
+in the case of our special soured milk we kill out, practically, all
+wild bacteria and germs, and the pure culture having the field to
+itself, we can conduct the operation at a higher temperature where the
+action of the bacteria is at its maximum, and so obtain the necessary
+lactification in the minimum of time.
+
+The appliances for the souring of milk on the domestic scale require
+some consideration. We propose to describe the principal forms of
+apparatus which have been put on the market for the purpose, and then to
+give such suggestions as may assist the ingenious in making apparatus
+for themselves. Those who wish for information on the subject of larger
+apparatus will find it in the following chapter.
+
+  [Illustration: FIG. 41--Photograph of Agar Culture,
+  inoculated with a lactic powder offered to consumers under
+  a fancy name. Working on the assumption that the presence
+  of lactic bacteria is inimical to the growth of septic
+  organisms, this preparation has been placed on the market.
+
+  The plate shows, however an abundance of colonies of
+  foreign organisms--sporogenous bacilli, _Staphylococcus
+  pyogenes albus_, and _Staphylococcus pyogenes aureus_.
+  These organisms are shown in the appended
+  photo-micrographs, and constitute impurities in the
+  preparation.]
+
+  [Illustration: Spore forming bacillus]
+
+  [Illustration: _Staphylococcus pyogenes albus_]
+
+  [Illustration: FIG. 42--Photograph of Test Tubes of Sterile
+  Milk, inoculated with a tablet preparation said to contain
+  pure cultures. The darker liquefied portion of the
+  tube-contents is due to digestion of the curd by
+  proteolytic bacteria, thus indicating impure culture. Pure
+  cultures of lactic acid bacteria coagulate the milk
+  uniformly, but do not produce any subsequent change in the
+  appearance of the culture, even after several months.]
+
+  [Illustration: FIG. 43--Photograph of Test Tubes of
+  Sterile Milk, each tube having been inoculated with a
+  tablet of a preparation said to contain pure cultures.
+  Here, again, there is evident peptonisation of the curd,
+  thus indicating infection by proteolytic ferments.
+  Cultures from these tubes demonstrated the presence of a
+  foreign organism. Microscopical examination failed to
+  disclose the presence of _Bacillus Bulgaricus_.]
+
+  [Illustration: FIG. 44--Photograph of Test Tubes of
+  Sterile Milk, inoculated with a tablet of
+  "Lactobacilline." In contra-distinction to those shown in
+  Figs. 42 and 43, these tubes exhibit homogeneous curdling
+  of the milk without any subsequent digestion or
+  peptonisation of the coagulum. This is indicative of the
+  purity of the culture.]
+
+The Society "Le Ferment" of Paris, which has been authorised by
+Professor Metchnikoff to prepare and supply to the public his sour milk
+culture, provides an apparatus for the treatment of the milk. It is
+shown in Fig. 45, which consists of a double box having the intervening
+space packed with a non-conducting material. It is provided with a
+tight lid. Inside, there is accommodation for two milk vessels, each
+with a capacity of about two thirds of a pint. The most difficult thing
+in the souring of milk is to maintain the temperature as nearly at 100�
+F. as possible while the culture is in action. This result is attained
+by filling the vessel in the middle with boiling water. The insulated
+walls hinder the escape of heat, and the quantity of boiling water used
+is calculated to maintain the temperature steady for the twelve hours of
+cultivation; but in cold, frosty weather it is necessary to refill the
+central vessel with boiling water in the middle of the period.
+
+  [Illustration: FIG. 45]
+
+The milk jars are washed with hot boiled water and turned upside down to
+dry. They should not be wiped with a cloth. Boil the milk to be treated
+for ten minutes, stirring it to promote evaporation, as it is
+advantageous to have it in concentrated form. Cool rapidly to 100� F. by
+placing the boiling vessel in cold water, add to each bowl one third of
+a tube of the culture in powder form, fill up with the boiled and cooled
+milk, stir well and cover. Place the jars in the box and fill the
+central vessel with boiling water, shut the lid tight, and do not open
+it (unless a fresh charge of boiling water is needed) for ten or twelve
+hours, when it will be ready for use. If the liquid culture is used (one
+small phial for each bowl) the milk should be cooled to 86� F. instead
+of 100� F., as with the powder. The culture is also supplied in tabloid
+form. The powder and tabloids keep well, but the liquid can only be
+relied on for about two months. The milk prepared as above should be
+stored in a cool place, the lids being kept on the bowls. It is good for
+about two days, after which it becomes too sour. It can be eaten with
+sugar, which not only sweetens it but is beneficial in affording
+additional suitable food for the acid-producing bacilli. If fresh milk
+cannot be had, condensed, sterilised, or pasteurised milk may be used,
+but, of course, fresh milk is best. Condensed milk should be diluted
+with two parts of boiling water and then treated like ordinary milk.
+
+An apparatus on similar principles is sold by the Maya Bulgare Company,
+Ltd., and is illustrated in Fig. 46.
+
+  [Illustration: FIG. 46--Soured Milk Apparatus of the Maya
+  Bulgare Company, Limited, consisting of an insulated box,
+  hot-water vessel, and covered vessels containing the milk
+  and culture. The apparatus consists of cabinet in deal,
+  Maya Bulgare ferment in 20-dose bottles, Maya Bulgare
+  ferment in 100-dose bottles, compressed Maya Bulgare
+  tablets in boxes of 8 tubes, Maya Bulgare caramels in
+  boxes of 40, reduced milk, china funnels, and
+  thermometers.]
+
+The box is insulated, but the door is on the side, the hot water vessel
+is underneath, and the covered vessels containing the milk and culture
+are placed on a shelf above. In the front of the illustration are shown
+the various packages in which the liquid and powder cultures are put up.
+The procedure is exactly the same as with "Le Ferment" apparatus.
+
+Lactic Ferments, Limited, make use of a different principle to maintain
+the temperature steady during the lactifying period. Their apparatus
+(Fig. 47) consists of a water vessel mounted on a stand. The milk
+vessels (tumblers) are placed in the water, and the temperature
+maintained at the proper figure by a small night light burning
+underneath. It is recommended that the milk should be placed in an
+earthenware jar or jug, which is stood in a pot of water kept boiling
+for an hour. After cooling add from three to six previously crushed
+tabloids of culture, and stir well with a glass rod which has been
+sterilised in boiling water. The milk is then transferred to three
+tumblers, which it should fill, and these are put into the water vessel,
+the water in which should be at about 100� F., and the night light
+started.
+
+  [Illustration: FIG. 47]
+
+Messrs. Allen & Hanbury, Limited, also make use of the night light to
+maintain the proper temperature during incubation in their "Sauerin"
+apparatus (Fig. 48).
+
+No water, however, is placed in the metal container. The procedure is
+the same as that already described, and both tablet and liquid pure
+cultures are supplied. For children it is recommended that the
+incubation should occupy from three to four hours only, in other cases
+eight to ten hours. Grated nutmeg, ground cinnamon, or other flavouring,
+and cream may be used with the soured milk.
+
+The night light is also employed in the "Veronelle" apparatus of Messrs.
+Clay, Paget and Company, Limited (Fig. 49).
+
+  [Illustration: FIG. 48.--Messrs. Allen & Hanbury's Soured
+  Milk Apparatus. They maintain the temperature by means of
+  a night light, and the culture they use they call
+  "Sauerin."]
+
+  [Illustration: FIG. 49.--Vironelle Apparatus for souring
+  milk, made by Messrs. Clay, Paget & Company, Limited. The
+  milk in this case is placed in an earthenware jar, and is
+  sterilised by placing in a saucepan of water and boiling
+  it. The culture is added after cooling, the period of
+  incubation being about six hours.]
+
+The containing vessel is of tin or aluminium, and has two stands, the
+high one for hot and the low one for cold weather, as in the latter
+case greater heat is needed to maintain the incubating temperature. The
+milk is placed in an earthenware jar and is sterilised by placing it in
+a saucepan of water and boiling it; continuing the boiling for half an
+hour. It is allowed to cool to about 98� F., and placed in the
+incubator, culture added, and the lamp lighted, the cover of the
+incubator being kept on. The period of incubation is given as six hours.
+To prepare the next day's supply a tablespoonful of the soured milk is
+retained and used instead of the culture. This may be continued for
+fourteen days, when a fresh start with culture is necessary. The soured
+milk will keep for thirty-six hours. Capacity, one and one half and two
+pints; also a large size for family use.
+
+For the preparation of soured milk on a small scale, one of the various
+forms of vacuum flasks now on the market may be used with satisfactory
+results. A little cold water must be poured into the flasks, and warm
+water added, until, by means of three to four changes, boiling water can
+be safely poured in without cracking the flask.
+
+This boiling water must be allowed to remain in for about twenty
+minutes, and then replaced by freshly boiled milk that has been cooled,
+so that its temperature in the flask is about 105� F. The culture of
+lactic organisms should then be added, the opening of the flask plugged
+with clean cotton-wool, and the cap screwed on.
+
+In an actual test, the temperature of the milk placed in such a flask
+was 105� F., at 7.30 P.M., and had dropped to 93� F. by 9 A.M., the
+following day. The milk was curdled, and possessed the normal acid taste
+of such cultures.
+
+The different types of apparatus are all quite simple, and it would be
+easy to make something at home. Get two round tins, the one less in
+diameter by from two to three inches than the other, put one or two
+pieces of wood across the bottom inside the larger tin, and fill up the
+space between with cotton-wool, which is an excellent non-conductor of
+heat. Place the smaller tin centrally inside the larger one. Fix three
+or four distance pieces of wood in the space between them, fill up with
+cotton-wool, leaving a little space at the top to permit the lid of the
+smaller tin to be fixed on. The boiling-water vessel may be a tin
+saucepan with a lid, but no handle, and its proper place would be on the
+bottom of the inner tin. A tripod stand made of three pieces of wire
+bound together, and with legs reaching past the hot-water vessel to the
+bottom of the tin, would support a false bottom of tin forming the shelf
+on which the vessels of milk to be treated would rest. These might be
+tumblers covered with tin lids. To prevent radiation through the lid of
+the inner tin, a thick pad or hood of cotton-wool packed between cloth
+would be placed over the top. A little experimenting would be necessary
+to determine the quantity of boiling water required to maintain the
+proper temperature.
+
+The soured milk obtained in the above manner is of the consistency of
+ordinary buttermilk; a separation of whey frequently takes place, and
+this may be poured off if desired. The taste and flavour should be
+pleasantly acid and agreeable, and both are distinctive enough to give a
+good idea of the purity of the product. In many places a more
+concentrated article is made by boiling down the milk to one half or one
+third of its bulk, and then fermenting it in the ordinary way. A kind of
+thick pudding is thus obtained, which is highly recommended both as an
+agreeable article of food and as a stronger medium for the support of
+the germs it is the purpose of the sour milk treatment to introduce
+into the digestive system.
+
+The cultures for making soured milk can now be had from all the leading
+wholesale and retail chemists, with directions as to the quantities to
+be used.
+
+It is very necessary that the milk used should be not only fresh and
+good, but also free from chemical preservatives. The effect of these is
+to inhibit the growth and development of bacteria, and they have
+therefore an injurious influence on the special lactifying germs it is
+our object to cultivate. Preservatives are now not nearly so much used
+as they were, a few years ago, and there should be no difficulty in
+obtaining milk free from them.
+
+For keeping both fresh and soured milk good a small ice-chest is an
+excellent device. The germs which are continually dropping into milk
+kept in open vessels in the air, even in cleanly surroundings, are
+mostly kept out in the close ice-chest, and the low temperature prevents
+in a natural way the development of the bacterial germs already in the
+milk. For the preservation of all kinds of foods the ice-chest is a
+capital investment, not to mention the benefit of having cooled drinks,
+etc., as required. They manage things well in this respect in the United
+States, where ice is regarded as a necessity in the summer time by even
+the poorest people, and is delivered with the same regularity as the
+milk.
+
+It is necessary to utter a word of warning as to certain forms in which
+the sour milk bacillus is being offered to the public. It is being
+compounded with sugar, chocolate, and other articles, and sold in the
+form of sweets, etc. There is no reliable proof that these preparations
+are valuable. Certainly, sugar is a medium in which the lactifying germs
+can live, but the quantity so introduced into the system must be very
+small compared with what is obtained from properly fermented milk. It
+takes some time, even with strong cultures, to fix the acid-producing
+germs in the large bowel where they are wanted, and until proper
+evidence is forthcoming that confectionery preparations are efficacious
+we would recommend that only the regularly fermented milk be used. It
+would save trouble, no doubt, to treat oneself with a few chocolate
+creams containing the necessary germs daily, but if the matter is taken
+up seriously it will be better to take some pains and stick to methods
+the efficacy of which has been demonstrated, leaving the others until
+their _bona fides_ has been proved. There are always enterprising firms
+who are prepared to simplify things for us, but we must make sure that
+their simplifications are warranted.
+
+
+
+
+CHAPTER VII
+
+THE PREPARATION OF SOURED MILK IN THE DAIRY
+
+
+There is a tendency in certain medical quarters to discourage the use of
+soured milk "made for profit." This view leaves out of account the fact
+that besides being of value in medicine, the article in question is also
+an excellent food, which, as we have seen, has been consumed by
+multitudes of people for ages in many parts of the world. There seems
+also to be satisfactory evidence that a larger percentage than usual of
+the people who make soured milk a staple of diet attain to a ripe old
+age. How does it become such a dangerous thing the moment the doctors
+get it into their hands? Of course if a man has an acute disease he
+places himself entirely in the hands of his medical man, and eats what
+is prescribed for him, or at least he ought to do so, and if he makes
+such a submission he is entitled at least to the comfort of being able
+to feel that his doctor is free from unreasonable prejudices. For the
+implication that an article "made for profit" is naturally suspect casts
+an unwarranted stigma on a large number of honourable people. There are
+dishonest tradesmen just as there are dishonest and careless doctors,
+but to saddle a whole class with the offences of a few would not be a
+justifiable proceeding in either case. Besides, it is not to the
+interest of the manufacturing chemist or the dairyman to turn out
+spurious cultures or bad soured milk, and on the whole we see no reason
+why they should not engage in the business.
+
+The widespread use of soured milk in other countries as a regular
+article of diet seems to indicate that all manner of people, except
+those suffering from diseases which necessitate medical regulation of
+diet, might with probable benefit to themselves add this article to
+their food list; and it looks as if a good many of them intend doing so,
+even if scandalised doctors threaten "to abandon the cure."
+
+The dairyman who knows his business does not need to be told of the care
+which is necessary to keep milk in good condition. The merely commercial
+consideration of avoiding loss has made him ready to inquire into the
+best means of prolonging the life of milk as a merchantable article.
+For a time he relied on chemical preservatives, but their day is now
+almost over, and filtration, pasteurisation, and cold storage have taken
+their place. Any one conversant with the trade knows how widely these
+methods have been adopted of late years; we may, therefore, assume that
+the average dairyman has at his command milk suitable for the incubation
+process.
+
+The demand for soured milk is not as yet a very large one, and the
+apparatus so far developed for its production is meant for the treatment
+of small quantities. After describing the principal appliances at
+present in the market we propose to make some suggestions as to the
+construction of larger apparatus.
+
+A firm which has given great attention to the question of maintaining
+fixed temperatures is that of Messrs. Charles Hearson & Co., Ltd. Their
+incubators for chicken hatching are known all over the world; and their
+appliances for biological incubation are very generally used in
+bacteriological laboratories. With such experience it was natural that
+they should turn their attention to soured milk apparatus, and the
+result is the "Lactobator" (Figs. 50 and 51).
+
+  [Illustration: FIG. 50.--"Lactobator" made by Messrs.
+  Charles Hearson & Co., Limited, which is used for the
+  incubation of pure culture in milk in a fairly large way.
+  The illustration shows the "Lactobator" closed.]
+
+  [Illustration: FIG. 51.--Messrs. Hearson & Company's
+  "Lactobator," showing the internal arrangements.]
+
+A copper vessel made to contain water has placed in it a stoneware jar
+which holds two gallons of milk; on the top is a lid which carries a
+thermometer for indicating the temperature of the milk. Heat is supplied
+by a gas ring under the copper vessel; and in the gas supply is the
+patent thermostat made use of by Messrs. Hearson also in their
+biological and poultry incubators, in which a capsule containing a
+liquid arranged to boil at a certain predetermined temperature is the
+regulating factor. When the liquid boils, the capsule expands, and by
+certain mechanical devices regulates the gas supply so as to produce
+exactly the temperature required.
+
+The procedure is as follows: The jar is filled with milk, and water is
+run into the copper vessel by the funnel until it runs over at the
+overflow pipe. The thermostat is lifted off and the full gas supply
+allowed to pass to the burner, the temperature of the milk brought up to
+180� F. and maintained for half an hour at this figure. The gas is then
+turned off, and cold water run through the funnel until the temperature
+of the milk registers 95� F. The culture is added, the lid replaced, and
+the thermostat put into the pocket at the side of the vessel; the gas
+relighted, and when the temperature reaches 100� to 106� F. the
+capsule of the thermostat will expand and close the gas to a peep, which
+is just sufficient to maintain the temperature within the above limits.
+After eight hours the incubation is completed.
+
+Edgar's patent apparatus, the "Lactogenerator," as provided by the Dairy
+Supply Co., Ltd., is shown in Fig. 52.
+
+  [Illustration: FIG. 52. Edgar's "Lactogenerator"]
+
+The milk is placed in a tinned copper-jacketed vessel and water run in
+through a vertical pipe until it runs off at the overflow. Two gas
+connections are required with cocks on each, the one to heat up the milk
+to the boiling point and maintain it at this for thirty minutes. A
+skimmer which has been placed in the milk lifts out the coagulated
+protein and albumen which rise to the top. The cock is then shut and
+cold water run through the jacket till the thermometer shows 90� F.,
+when the culture is added, and the other gas supply with the regulator
+turned on, and the temperature is automatically maintained at about 90�
+F. Time of incubation eight to nine hours. It is recommended to turn
+cold water into the jacket at the end of the period to prevent
+overincubation.
+
+A somewhat similar apparatus is that of the Willows Refrigerating Co.,
+Ltd. (Fig. 53), with the exception that it has no automatic heat
+regulator. It is made of tinned steel, and the operations are the same,
+but the sterilising temperature (obtained by a gas ring or hot plate) is
+given as 180�, and the incubating temperature 100� to 104� F. for a
+period of twelve hours. Presumably this temperature is maintained by a
+small gas jet or other similar source of heat. The capacity is two
+gallons.
+
+  [Illustration: FIG. 53
+
+  Apparatus of the Willows Refrigerating Co., Ltd.]
+
+In the apparatus hitherto described the milk is sterilised in bulk, and
+is filled into bottles or jars after incubation, which is not a
+desirable thing to do, unless the soured milk is for immediate
+consumption, as there is likely to be contamination with injurious germs
+from the atmosphere. In the domestic apparatus the milk is usually
+incubated in covered jars in which it can be kept until required for
+use, and the practice on the larger scale should be the same.
+
+The Dairy Outfit Co., Ltd., have recognised this in their "Lacto"
+apparatus (Fig. 54).
+
+  [Illustration: FIG. 54
+
+  "Lacto" Apparatus of the Dairy
+  Outfit Co., Ltd.]
+
+A cylindrical vessel is set loosely on a stand, beneath which is a lamp
+calculated to maintain the incubating temperature. The milk is placed in
+bottles with metal screw tops, and these are put into the cylindrical
+vessel; water is run in round them through the side funnel, the vessel
+lifted off the stand, and heated to sterilising point on a stove. Cold
+water is then run in through the funnel until the temperature is low
+enough for incubation. Culture is added to each bottle and the lids
+screwed on, the vessel lifted on to its stand, and the lamp lighted. The
+cover of the apparatus has a thermometer fixed on it.
+
+On the large scale the treatment of the milk would take place entirely
+in the jars in which it would be sent out, and the sterilisation and
+incubation would be conducted in different pieces of apparatus. The
+sterilisation would be effected either (1) by direct steaming, or (2) by
+hot water heated by steam. Fig. 55 shows the first type of
+sterilisation. The tank is of wrought iron or steel with strengthening
+pieces of angle iron. The door, with pulleys and counterweight for easy
+handling, is fastened steam-tight by hinged bolts. The apparatus is
+mounted on a stand at a convenient height for handling the bottles; and
+in front is another stand with channel iron rails to take the waggon in
+which the bottles or jars to be sterilised are packed. When the door is
+fast, steam is turned on, and regulated to produce the proper
+temperature by the thermometer fixed in the shell, in which a pressure
+gauge is also secured. After sterilising, the door is opened and the
+waggon drawn forward to the outside, allowed to cool, or removed
+elsewhere to cool, and allow space for a new charge.
+
+  [Illustration: FIG. 55.--Sterilising Apparatus for
+  sterilising milk on the large scale. The bottles of milk
+  are sterilised, and the culture can then be added, and the
+  incubation allowed to proceed in an insulated chamber.]
+
+The second method of sterilising is by hot water, as in Fig. 56. The
+bottles or jars are placed on a perforated false bottom in the
+rectangular tank, water run in up to the necks, and steam turned on; the
+lid is fastened with hinged and hooked bolts; a thermometer fastened in
+the lid, and with a long stem enclosed in metal, indicates the
+temperature. At the end of the sterilising process cold water is turned
+on, and at the same time the overflow water cock is opened; the cold
+water gradually reduces the temperature, and the incubating point is
+quickly reached.
+
+  [Illustration: FIG. 56 Another Method of Sterilising
+  (Dairy Supply Co., Ltd.).]
+
+Incubation in bottles or jars, sterilised in these ways, can best be
+conducted in an insulated room, with say, six inches of silicate cotton,
+granulated cork, or washed cow hair packed between two-inch by six-inch
+battens, covered with matching on either side, and lined with sheet
+zinc. It would be an advantage to have an air-lock or anteroom into
+which the waggons or trays of sterilised jars could be run, and the door
+of the anteroom closed before the door of the insulated room is opened.
+This would tend to prevent variations of temperature in the room, and
+also, by checking free communication with the outside air, decrease
+contamination. The waggons of jars would be run in, and culture added to
+each jar by a sterilised pipette. The atmosphere of the room would be
+kept pure by running in air frequently through a filter of moist
+cotton-wool by means of an electric fan, and at intervals the interior
+would be sterilised by the use of formalin vapour.
+
+
+  [Illustration: _Details of an American Apparatus for
+  Preparing Soured Milk_
+
+  FIG. 57
+
+  The figures give diagrams A, B, C, and D of an apparatus
+  useful for the preparation of lactic foods. The incubating
+  can A, is made of block tin, and is intended to contain
+  the milk. B, the warm water container, should be a stout
+  walled vessel with a circular aperture in the lid, through
+  which the incubating can may be passed, and clamped down
+  as in C.
+
+  B is fitted with three stout iron legs, which should be
+  sufficiently long to allow of a small lamp or gas-jet
+  being placed beneath the container to maintain a uniform
+  temperature.
+
+  D gives an external view of the apparatus.
+
+  For the preparation of soured milk, separated milk is
+  placed in the incubating can, and heated up to 100� C.
+  (212� F.) for thirty minutes. It is then allowed to cool
+  to room temperature, and the culture, or tablet containing
+  the lactic acid bacteria, is then added, and thoroughly
+  stirred for a minute or so. The can is then immersed in
+  the warm water container and kept at a temperature of 86�
+  F. to 104� F., according to the organisms used, for ten to
+  twelve hours. By the end of this time the milk ought to be
+  converted to a jelly-like mass, and after being stirred
+  vigorously for a short time, may be cooled on ice, and is
+  then ready for consumption.]
+
+The incubating temperature could very conveniently be maintained by an
+electric radiator, and as the insulation would largely prevent leakage,
+the amount of electric current used would not be large. The regulating
+apparatus might consist of a thermometer with platinum wires fused
+through the stem at the proper temperature, say 100� F. When the mercury
+rises to this figure it will complete the circuit of a battery which
+will actuate certain well-known devices for turning off the current
+which actuates the radiator. In this way a very fine automatic
+arrangement would be achieved. Steam pipes might be used instead of the
+radiator, and the thermometer above described could be used in this case
+also, with appliances to cut off the steam.
+
+On the large scale, labour-saving appliances, such as the mechanical
+brush jar and bottle washer, and the automatic filler for jars or
+bottles, would be employed, and an overhead trackway for carrying the
+trays of jars from the steriliser to the incubator would be a great
+convenience. A further adjunct of considerable importance would be a
+cold room, worked either by ice or a refrigerating machine, in which the
+jars could be stored after incubation, so as to arrest the process of
+lactification, and maintain the soured milk in good condition until
+required for use.
+
+
+
+
+CHAPTER VIII
+
+SOURED MILK IN HEALTH AND DISEASE
+
+
+When people are ill the best thing they can do is to place themselves in
+the hands of the doctor, who will try to regulate their lives, including
+their diet, in accordance with the conditions which science suggests as
+the most likely to lead to their recovery.
+
+It is not the aim of this book to teach persons who should be under
+medical treatment to doctor themselves; soured milk may or may not be
+beneficial in their case--that is for the medical man to say; and
+further, if it should be beneficial the doctor ought to have its
+preparation under his control. Slight differences in quality and purity
+may count for much in cases of acute disease, differences which might
+not matter to the person who requires no medical attention, and who
+consumes the article as a health-giving food. A considerable body of
+evidence is already on record as to the potency in certain cases of
+soured milk as a curative agent, and it seems to have taken its place in
+medicine as a recognised remedy.
+
+There is a wide field of usefulness, however, outside of the strictly
+medical one. Professor Metchnikoff has collected many striking examples
+of individuals and peoples inhabiting different parts of the world, who
+thrive, and in many cases attain to a great age, and whose diet consists
+largely of soured milk. He has made a wide and general inquiry into the
+causes which tend to shorten life, and makes out a strong case in
+support of the view that in many cases this is the result of what is
+called auto-intoxication or self-poisoning. In man and in the mammalia
+generally, the colon or large intestine is very largely developed; this
+organ is not of much value in the digestion of food, and seems to be
+chiefly a receptacle for waste material; it is, as a rule, extremely
+rich in bacterial flora, which produce putrefactive changes in the waste
+material. As a result various poisonous principles are evolved, and
+these find their way into the blood, accompanied frequently, there is
+every reason to believe, by the injurious bacteria themselves. In this
+way many diseases and ailments are produced which shorten life. The
+inquiry then naturally turns to what is the best way of dealing with
+this state of matters. It is known that the bacteria referred to
+flourish best in alkaline or at least non-acid surroundings, and it is
+known that these conditions very frequently exist in the large
+intestine. Acids are the best antiseptics; they have been used from time
+immemorial as preservatives; pickles are preserved in vinegar or acetic
+acid, and when milk is allowed to sour under proper conditions, the
+germs of putrefaction are destroyed or their activity inhibited, and it
+keeps a considerable time. Doubtless, in hot countries, it was this
+property of lactic acid which first led to milk being artificially
+soured with a view to its preservation as an article of food. So
+powerful is lactic acid in this respect that it is a custom in some
+countries to preserve meat by placing it in soured milk.
+
+How can acids be applied so as to control the bacterial flora of the
+large intestine? Not in the ordinary way, because, when administered
+through the mouth, they are used up long before they can penetrate to
+the colon. The brilliant idea occurred to Professor Metchnikoff, of
+administering acid-producing germs which might work their way through
+the digestive system, and, reaching the large intestine, produce the
+acid required. After much experimenting the bacillus of Massol,
+_Bacillus bulgaricus_, was adopted as the most suitable. The Bulgarian
+bacillus is an extremely vigorous one, multiplying with great rapidity,
+and persisting in conditions that would be inimical to other microbes.
+The growth and development of bacteria is interfered with by the
+products of their own activity; thus, ordinary lactic-acid-producing
+organisms die when a certain amount of lactic acid has been developed;
+the same fate overtakes the Bulgarian bacillus, but it survives longer
+and is able to produce as much as two and one half per cent. of lactic
+acid in milk before it ceases operations. It seemed therefore the most
+likely to be able to survive the journey through the digestive system.
+Experiments fully bore out this supposition, as no great difficulty was
+encountered in naturalising the Bulgarian bacillus in the large
+intestine, not only in milk cultures, but grown in solution of malt,
+bouillon, etc. It thrives in all kinds of sugar, and therefore can be
+administered in a variety of media, very beneficial results following in
+many cases. Direct tests showed a large reduction of the injurious
+intestinal flora when the Bulgarian bacillus had been naturalised in
+the colon, and the bacillus persisted long after it had ceased to be
+administered. Specialists who have taken up the subject report the cure
+of many ailments through the agency of soured milk, and it seems to have
+entered upon a lengthening career of medical usefulness.
+
+The fact of so many old people being found in countries where soured
+milk is a staple of diet naturally raises the question as to whether its
+general use in other countries might not have a beneficial effect on
+health and longevity. Its usefulness as a remedial agent in certain
+diseases is already demonstrated; is there not a strong probability,
+amounting almost to a certainty, that its consumption by people in
+health would tend to ward off many ailments and prolong life? Of course
+there will be some for whom it is not suitable; there are people who
+cannot eat strawberries without discomfort, but no one thinks of
+prohibiting the general use of the fruit on that account. In the matter
+of diet the person in health, if he exercises ordinary care, may be left
+to find out for himself what suits him. The soured milk remedy is not a
+disagreeable one, as, when properly prepared, the article forms both a
+pleasant and refreshing article of diet. The question of getting the
+right article, however, is a very important one. Milk is a splendid
+rearing ground for many bacteria, some of which are very injurious;
+among these may be pathological germs, the seeds of tuberculosis,
+enteritis, etc. The danger with soured milk is, that in the process of
+culture we develop the best condition for the increase of these when
+they preponderate, or when, through the use of bad cultures, the
+lactic-acid-producing bacteria are absent, or present only in small
+numbers. By the thorough boiling of the milk, we get rid of all living
+bacteria and nearly all spores or germs, and by scrupulous cleanliness
+in the vessels used--scalding or even boiling them, and allowing them to
+dry naturally in an inverted position--we greatly diminish the
+probability of infection with fresh injurious germs from the atmosphere.
+All depends on the purity of the culture employed; this can now be
+obtained, prepared in the most careful manner, from wholesale chemists
+making a speciality of its manufacture.
+
+As we have seen, even the Bulgarian bacillus is ultimately killed by the
+products of its own activity, and the natural corollary is, that the
+life of cultures cannot be a long one. Only those cultures should be
+bought which are labelled with the date to which they are guaranteed to
+maintain their efficiency. With fresh good milk, careful boiling,
+scalding, and cleanliness with regard to the containing vessels, and the
+means of maintaining the incubating temperature for ten or twelve hours,
+there is not the slightest difficulty in preparing perfectly reliable
+soured milk. There are simple tests which will sufficiently guide the
+experimenter; the soured milk should not be too acid to the taste, and
+it has a flavour of its own by which its quality can be recognised. The
+litmus test-papers mentioned in the chapter on the chemistry of milk are
+very useful; both the red and the blue papers should be obtained and
+used first of all in testing the quality of the fresh milk. After
+incubation the soured milk should turn the blue paper decidedly red; if
+this does not occur, test it with the red paper; if the latter turns
+blue it is proof that the wrong fermentation has taken place--that
+putrefactive germs have gained the upper hand. The most probable
+explanation is, that the culture is bad, the Bulgarian bacillus is not
+present, or if so, only in small numbers. With these simple tests,
+combined with proper care, one cannot go far wrong. The Eastern nations
+who prepare soured milk in various forms do not exercise the care we
+have predicated, but they seem to make the article of fairly constant
+and good quality. It has been suggested in explanation that, as the
+ordinary flora differs in different countries, the bacterial flora
+varies in a similar manner, and that in these Eastern countries
+injurious bacteria are not so prevalent in the atmosphere as they are
+with us.
+
+It is also said that the flavour of the soured milk prepared in Bulgaria
+is quite different from that prepared in Paris, London, or New York; one
+reason probably is that the "maya" or ferment used in Bulgaria contains
+several other organisms besides the Bulgarian bacillus, which raises the
+question whether a pure culture of one bacillus is the best to use.
+
+Professor Metchnikoff found that this bacillus alone had certain
+defects; it attacks fat and is apt to give a tallowy taste when cream is
+present in the milk. He therefore associated with it another
+lactic-acid-producing organism, and this combination is the basis of his
+culture called "lactobacilline." The presence of yeasts, which occur in
+the Eastern ferments, has been advocated by some; the yeast in
+association with the lactic organisms produces a small amount of
+alcohol. The question of the composition of the culture will have to be
+fought out by the experts, but meantime, if we go to the right source,
+we have good enough cultures to go on with.
+
+A good deal can be said for the use of skimmed or separated milk instead
+of whole milk. Cream as a rule contains far more bacteria than the rest
+of the milk, and we therefore start from a surer foundation when it is
+removed; besides, the mechanical separator, now so largely used, removes
+slime and other impurities from the milk, and these also are hotbeds of
+bacteria.
+
+Soured milk may be taken at any time, the first thing in the morning,
+before or after meals, or the last thing at night. The quantity will
+vary with the individual, but from half a pint to a pint is a fair
+amount for daily use. If one wishes to have the maximum effect it is
+necessary for the time being to curtail the use of butcher's meat and
+substitute fish, yolk of eggs, and other similar foods; not much alcohol
+should be taken, and smoking might be reduced to a minimum. Those who
+cannot take even skimmed milk may use whey in which to cultivate the
+bacillus; it is not desirable to employ the whey which has been
+separated by the use of rennet, as in cheese- or junket-making. A better
+article is obtained by adding a very small quantity of pure hydrochloric
+acid to milk which has been boiled, and then filtering through a sieve,
+which retains the curd while the liquid whey passes through; a pinch of
+soda is added to neutralise the excess of acid, and, after boiling, the
+liquid should turn red litmus paper blue; it is then ready for the
+addition of the culture and incubation in the same manner as with milk.
+A solution of malt--the extract dissolved in hot water is
+convenient--may also be used instead of milk, and strongly malted bread
+or biscuits are excellent to take with the soured milk or cultures in
+other mediums, to supply food for the bacillus in the form of malt
+sugar. Other sugars, cane or grape, are also very useful, and may be
+taken in the form of fruit juices, syrups, confections, jams, sweet
+puddings, etc.
+
+We lay stress on the use of soured milk or other cultures of the
+Bulgarian bacillus by people in health as a probable preventive of
+disease and a possible agent in the lengthening of life, but it may be
+of interest to give a short account of its use by medical men in the
+treatment of various ailments. An English authority on the subject, Dr.
+Herschell, states that the symptoms of the poisoning of the system by
+the toxic substances produced by injurious bacteria in the large
+intestine may include headaches, misery and depression of spirits,
+drowsiness and stupor, giddiness, dimness of sight and dizziness,
+fatigue without obvious cause, both of the muscles and brain, fear,
+panic, and nervousness, disagreeable sensations in the limbs or face,
+such as numbness, tingling, or prickling, crawling sensation of weight
+or of heat or cold, dyspepsia of the sort where there is a deficiency of
+hydrochloric acid and pepsin in the gastric juice, accompanied by
+flabbiness and loss of power in the muscles of the stomach, and
+characterised by flatulence, nausea, loss of appetite, with discomfort
+and weight after food, furred tongue, emaciation, earthy colour of the
+skin, offensive perspiration and the other signs of biliousness,
+enlargement of the liver, and an�mia. These symptoms may have other
+causes, and when one or several of them are present a chemical and
+physical examination of the urine and f�ces is necessary to prove that
+they have resulted from auto-intoxication. When this is shown the
+soured milk treatment is indicated, and many striking cures are detailed
+as witnesses to its efficacy. The liver and kidneys are the natural
+guardians of the body against the toxines we are speaking of, and
+frequently they are over-strained; the soured milk treatment greatly
+lightens their load. In malignant disease of the stomach, soured milk
+will frequently be retained when all other foods are rejected. In cases
+of neurasthenia and gout it has also proved of value, and in the
+"run-down" condition which is so common in middle life. Chronic
+diarrhoea and certain forms of constipation have in numerous instances
+yielded to the treatment, the whey culture being usually found the most
+suitable. Then, in some forms of an�mia, the lactic acid cultures have
+proved most successful, and, as a means of rendering the
+gastro-intestinal track aseptic previous to operations, they have proved
+of considerable value.
+
+If all this has been accomplished in a year or two, what may not we look
+forward to in the future when more extended use and experiment shall
+have more fully exhausted the possibilities of the cure? But if we
+follow the example of the different nations who have so long used
+soured milk as a regular article of diet, does it not seem probable that
+we may eliminate some, at least, of the causes of ill-health that call
+for the intervention of the doctor?
+
+The human organism is by no means perfect; we have within us many
+defective parts, and some organs whose working seems to be against the
+welfare of the economy. It has now been clearly shown that one of the
+chief of these is the large intestine, as to the use of which only vague
+and unsatisfactory theories have been formed. There can be no doubt as
+to the damage which it frequently inflicts on the system, and, thanks to
+the researches of Professor Metchnikoff and other investigators, we seem
+to be in possession of a natural remedy which is sufficient to deal with
+the evils it produces.
+
+
+  FOOTNOTES:
+
+  [1] _Discoveries in Nineveh and Babylon_, by Layard, chap.
+  xiii.
+
+  [2] Ex. xviii. and xxiii.; Lev. ii. and xi.
+
+  [3] _Encyclo. Biblica._
+
+  [4] Burckhardt and Doughty.
+
+  [5] _Annals of Dairying in Europe_, by Loudon M. Douglas.
+
+  [6] Burckhardt, _Bedouins_.
+
+  [7] This word is spelt in a great many ways by different
+  writers: _Yoghourt_ would seem to be the one most
+  favoured.--AUTHOR.
+
+  [8] _Damascus and Palmyra_, by Chas. G. Addison, 1838.
+
+  [9] _Travels in Syria and the Holy Land_, by Burckhardt,
+  1822.
+
+  [10] _Lands of the Saracens_, by B. Taylor.
+
+  [11] _Travels through Sweden, Finland, and Lapland and to
+  the North Cape in the years 1798 and 1799_, by Joseph
+  Acerbi, 1802.
+
+  [12] Letter to the author, from Mr. H. Cavendish Venables,
+  British Vice-Consul at Varna.
+
+  [13] _One Hundred and Twenty Years of Life_, by Reinhardt;
+  _The Secret of Longevity_, by an F.R.M.S.
+
+  [14] _Foods, their Composition and Analysis_, by A. W.
+  Blyth.
+
+  [15] _Dictionary of Applied Chemistry_, by T. E. Thorpe,
+  C.B.
+
+  [16] _Koumiss or Fermented Mares' Milk and its Uses, and
+  the Treatment and Cure of Pulmonary Consumption and Other
+  Diseases_, by L. Carrick, M.D., 1881.
+
+  [17] _Transactions of the Royal Society of Edinburgh_,
+  vol. i.
+
+  [18] Clarke's _Travels_, 1810.
+
+  [19] 1845.
+
+  [20] _Dictionary of Applied Chemistry_, by Thorpe.
+
+  [21] A leathern bottle.
+
+  [22] "I have brought forward Tchembulatof's receipt, which
+  differs from Bogoyavlensky's in the use of a larger
+  quantity of millet-flour, and in the boiling of the latter
+  apart from the milk. Dr. Postnikof's plan is the
+  following: Half a pound of millet-flour and a quarter of a
+  pound of malt are mixed with a sufficient quantity of
+  honey to form a paste, which is put into a clean jar,
+  covered with a linen cloth, and placed on a warm stove.
+  The mass soon begins to rise, and is then taken out,
+  wrapped in a piece of muslin, and dropped into a clean
+  earthenware vessel, containing about a quart of new mares'
+  milk, which is placed in the same temperature that the
+  paste was kept in. As soon as signs of fermentation begin
+  to show themselves in the fluid, the paste must be
+  removed, while the milk, after being stirred, should be
+  left in the same temperature till bubbles appear (only in
+  very small quantities) on its surface. The ferment is then
+  ready."
+
+  [23] _Food and the Principles of Dietetics._
+
+  [24] _Food and the Principles of Dietetics_, by Robert
+  Hutchison, M.D.
+
+  [25] _Bacteria in Milk and its Products_, by Conn.
+
+  [26] _Dict. App. Chem._, Thorpe.
+
+  [27] _Nature_, July 23, 1884.
+
+  [28] _The Exploration of the Caucasus_, by Duncan W.
+  Freshfield, 1896.
+
+  [29] Quoted by George M. Sternberg, M.D., LL.D.,
+  _Text-Book of Bacteriology_, 1898.
+
+  [30] _Encyclo. Biblica._
+
+  [31] Conn.
+
+  [32] _Cyclo. of Biblical Lit._, M'Clintock and Strong, and
+  Burckhardt's _Arabia_.
+
+  [33] _The Indian Medical Gazette_, Sept., 1909, "A New
+  Lactic Acid producing Streptothrix," by Gopal Ch.
+  Chatterjee, M.B.
+
+  [34] In their studies on Leben in the _Annales de
+  l'Institut Pasteur_ of 1899, Rist and Khoury, in speaking
+  of the amount of lactic acid produced by _Streptobacillus
+  lebenis_ in milk, say "Nous avons mesur� cette acidit�
+  dans une culture sur petit lait de vingt-quatre heures;
+  elle �tait .261 grms. per cent. exprim�e en acide
+  lactique," which will make the amount of lactic acid
+  produced in one litre of milk 2.61 grms. The production of
+  this small amount of lactic acid does not tally with the
+  ordinary view of the vigorous lactic-acid-producing power
+  of the bacillus.
+
+  [35] _Prolongation of Life._
+
+  [36] _Prolongation of Life._
+
+  [37] An accurate census of Bulgaria is being prepared and
+  will exhibit the cases of long life in that country.
+
+  [38] See A. Rosam, _�sterreichische Molkerei Zeitung_, 15,
+  p. 31.
+
+  [39] _Revue g�n�rale du Lait_, vii., pp. 8 and 9 (letter
+  from Dr. Otakar Laxa of Prague, Bohemia, to the author).
+
+  [40] _On the Prolongation of Human Life_, by �lie
+  Metchnikoff; also _The Century Magazine_, Nov., 1909, "The
+  Utility of Lactic Microbes," by the same author.
+
+  [41] _Century Magazine_, Nov., 1909.
+
+  [42] See _Annals of Dairying in Europe_, by Loudon M.
+  Douglas.
+
+  [43] Adapted from a report by Robert E. Turnbull, in _Live
+  Stock Journal_.
+
+  [44] _Facts about Milk_, by R. A. Pearson, B.S.,
+  Washington.
+
+  [45] _Care and Handling of Milk_, Marshall and Wright,
+  Bulletin 221, Michigan, 1904.
+
+  [46] _Journal of the Royal Society of Arts_, March 6,
+  1908--"Modern Dairy Practice," by Loudon M. Douglas.
+
+  [47] Skolotowski, _Wratsch_, 1883 (Russian), from
+  Codwyssozki.
+
+  [48] Podowyssozki, _Zeitschr. f. diat. u. physik.
+  Therapie_ vol. v., 1901, p. 570.
+
+  [49] Hammersten, _Jahresb. u. d. Fortsch. d. Tierchem_,
+  1886, Bd. 16, p. 163.
+
+  [50] Essaulow, _Dissert. Moscow_, 1895, _Abstr., Koch's
+  Jahresb._, 1895, Bd. 6, p. 222.
+
+  [51] Kern, _Bulletin Soc. des Naturalistes de Moscow_,
+  1881, 3, p. 141.
+
+  [52] Krannhals, _Deutsch. Arch. f. Klin. Med._, 1884, Bd.
+  35, p. 18.
+
+  [53] Beijerinck, _Centralbl. Bakt. Par._, 1889, Bd. 6, p.
+  44.
+
+  [54] Scholl, _Die Milch_, Wiesbaden, 1891, p. 38.
+
+  [55] Adametz, _Centralbl. Bakt. Par._, 1889, Bd. 5, p.
+  116.
+
+  [56] Freudenreich, _Landw. Jahrb. d. Schweiz._, 1896, vol.
+  x., p. 1.
+
+  [57] Nikolaiewa, _Annals of the Botan. Lab. of the Med.
+  Inst. for Women_, No. 10. St. Petersburg, 1907.
+
+  [58] Kuntze, _Centralbl. Bakt. Par._, 1909, 24, p. 101.
+
+  [59] See Chap. II.
+
+  [60] Rubinsky, _Centralbl. Bakt. Par. II._, 1910, vol.
+  xxviii., p. 161.
+
+  [61] Biel, _Jahresb. �. d. Fortschr. d. Tierchem_, 1886,
+  16, p. 159.
+
+  [62] Allik, _Dissertat. Dorpat._, 1896, 19, p. 303.
+
+  [63] Fleischmann, _Lehrb. d. Milchwirtschaft_, 2d edition.
+  Bremen, 1898.
+
+  [64] Rist and Khoury, _Annal. Pasteur_, 1902, 16, p. 65.
+
+  [65] Guerbet, _Comptes Rendus_, 1906.
+
+  [66] Weigmann, _Lafar's Handb. d. Techn. Mykol._, 2d
+  edit., 1905, vol. ii., p. 134.
+
+  [67] Emmerling, _Cent. Bakt. Par._ 1898, vol. iv., p. 418.
+
+  [68] Lindner, _Mikroscop. Betriebscontrolle, i. d.
+  G�rungsgew_, 3d edit., Berlin, 1901.
+
+  [69] Kalantharianz, _Dissert. Berlin_, Abs. in _Koch's
+  Jahresb._, 1898, Bd. 9.
+
+  [70] Luerssen and K�hn, _Centralbl. Bakt._
+
+  [71] Piorkowski, _Sitzungsber. der Berl. med. Ges._, Nov.,
+  1907.
+
+  [72] Metchnikoff, _The Prolongation of Life._
+
+  [73] Grigoroff, _Revue M�dicale de la Suisse Romande_,
+  1905, p. 10.
+
+  [74] Grixoni, _Abstr. Cent. Bakt. Par._ 11, 15, p. 750.
+
+  [75] Freudenreich and Jensen, _Cent. Bakt. Par._ 11, 1897,
+  3, 545.
+
+  [76] Moro, _Wien. klin. Wochenschr._, 5, 1900.
+
+  [77] Makrinoff, _Cent. Bakt. Par._ 11, 1910, vol. xxvi.,
+  p. 374.
+
+  [78] White and Avery, _Cent. Bakt. Par._ II, 1909, vol.
+  xxv., p. 161.
+
+  [79] Hastings and Hammer, _Research Bull., Wisconsin
+  Experimental Station_, 6, 1909.
+
+  [80] Boutroux, _Comp. Rend._, 86, 1905, 605.
+
+  [81] Richet, _Comp. Rend._, 86, 1905, 550.
+
+  [82] Koning, _Milchw. Zentralbl._, 1905, 1, 280.
+
+  [83] Heinemann, _Centralbl. Bakt. Par._ 1908, 21, 57.
+
+  [84] Chap. I.
+
+  [85] Metchnikoff, _The Prolongation of Life_, 1908, p.
+  161.
+
+
+  INDEX
+
+
+  A
+
+  Acerbi, 8
+
+  Acidity of milk, 64
+
+  Adametz on keffir, 92
+
+  Albumen, 52
+
+  Alcoholic fermentation, 17, 84
+
+  Allen & Hanbury's apparatus, 132
+
+  American incubating apparatus, 149
+
+  Analysis of milk, 48, 61
+
+  Aneyza Bedouins, 2
+
+  Arabs, 2
+
+  Arak�, 106
+
+  Ash of milk, 56
+
+
+  B
+
+  _Bacillus acidi lactici_, 107, 112
+
+  _Bacillus acidophilus_, 110, 112
+
+  _Bacillus bulgaricus_, 39, 46, 82, 108, 110, 123, 154
+
+  _Bacillus casei_, 113
+
+  _Bacillus caucasicus_, 92, 94, 95, 119
+
+  _Bacillus caucasina_, 39
+
+  _Bacillus coli_, 45
+
+  _Bacillus esterificans_, 96
+
+  _Bacillus keffir_, 96, 97
+
+  _Bacillus lebenis_, 105
+
+  _Bacillus matzoon_, 109, 110
+
+  Bacillus of long life, 46
+
+  _Bacillus putrificus_, 122
+
+  _Bacillus subtilis_, 90, 92, 107
+
+  Bacteria in milk, 76
+
+  Bacteriology of fermented milks, 84
+
+  _Bacterium acidi lactici_, 92, 96
+
+  _Bacterium a�rogenes_, 92, 96
+
+  _Bacterium coli commune_, 119, 122
+
+  _Bacterium sardous_, 110, 111
+
+  Balkan Peninsula, 4
+
+  Bedouins, 2
+
+  Beijerinck on keffir, 91
+
+  Biestings, 63
+
+  Biology of the keffir grain, 90
+
+  Blood, water contents of, 50
+
+  Bourgoul, 6
+
+  Bulgarian maya, 10, 109
+
+  Bulgaricus group, cultural characteristics of, 115
+
+  Burckhardt, 6
+
+  Butin, 51
+
+  Butyric acid fermentation, 16
+
+  Butyrin, 51
+
+
+  C
+
+  Camels' milk, 2
+
+  Caprinin, 51
+
+  Capronin, 51
+
+  Caprylin, 51
+
+  Carrick on koumiss, 18
+
+  Casein, 52, 53
+
+  Centenarians in Servia, Bulgaria, and Roumania, 41
+
+  Chatterjee on Dadhi, 38
+
+  Chemistry of milk, 47
+
+  Chocolate preparations and the soured-milk bacillus, 137
+
+  Citrates in milk, 57
+
+  Clay, Paget & Company's apparatus, 132
+
+  Coagulation of casein, 59
+
+  _Colitis_, 45
+
+  Colostrum, 63
+
+  Constituents of milk, 48
+
+  Continuous apparatus for producing soured milk, 81
+
+  Creamometer, 62
+
+
+  D
+
+  Dadhi, 15, 38
+
+  Dairy Machinery & Construction Company's apparatus, 80, 82
+
+  Dairy Outfit Company's apparatus, 145
+
+  Dairy Supply Company's apparatus, 143;
+    steriliser, 148
+
+  Dirt in milk, 63
+
+  Diseases of keffir grains, 97
+
+  _Dispora caucasia_, 34, 90
+
+  Dried sour milk, 5
+
+  Duclaux, 51
+
+
+  E
+
+  Edgar's "Lactogenerator," 143
+
+  Eggs, yolk of, 52
+
+  _Enteritis_, 45
+
+  Enzymes in milk, 57
+
+  Equipment for town's dairy, 80
+
+  Essaulow on keffir, 89, 92
+
+
+  F
+
+  Fat of milk, 50
+
+  Ferments at the altar, 3
+
+  Fl�gge, 35
+
+  Freshfield on keffir, 33
+
+  Freudenreich, 92
+
+
+  G
+
+  Gaseous fermentation, 84
+
+  Gay-Lussac, 17
+
+  Gioddu, 107
+
+  Globulin, 54
+
+  Grieve, Dr. John, on koumiss, 19
+
+
+  H
+
+  Hammerstein on keffir, 89
+
+  Handling of milk, 68
+
+  Health and disease, 151
+
+  Hearson & Company's "Lactobator," 141
+
+  Hebrews, 3
+
+  Houran, inhabitants of, 6
+
+  Hueppe, 16
+
+  Hutchinson, Dr. H. B., bacillus from English market milk, 120
+
+  Hutchison on koumiss, 30
+
+
+  I
+
+  Ice chest, 136
+
+  Impure cultures, 158
+
+  Incubators, 141
+
+  India, 1
+
+  International Dairy Federation, 68
+
+
+  J
+
+  Jebours, 3
+
+
+  K
+
+  Kalmucks, 20
+
+  Keffir, 15, 32, 85;
+    old, 88
+
+  Keffir grain, biology of, 90
+
+  Kephir, 34, 85.
+    _See also_ Keffir.
+
+  Keshk, 6
+
+  Keshk-leben, 6
+
+  Koumiss, 15, 18;
+    Bogoyavlensky's method of preparation, 28, 98;
+    analysis, 102;
+    artificial, 102
+
+  Krannhals on keffir, 91
+
+  Kuntze, 95
+
+
+  L
+
+  Lactic acid, bacillus, 16;
+    cultures, 55;
+    fermentation, 16, 84;
+    Ferments apparatus, 131
+
+  "Lacto" apparatus, 145
+
+  "Lactobacilline," 158
+
+  _Lactobac. caucasicus_, 91
+
+  _Lactobacillus keffir_, 94
+
+  Lactometer, 64
+
+  Lapland, 8
+
+  Laurin, 51
+
+  Layard, 2
+
+  Leben, 15, 37, 104
+
+  Leben Ra�b, 104
+
+  Lecithin, 52
+
+  "Le Ferment" apparatus, 128
+
+  Liebig, 17
+
+  Longevity, 155
+
+
+  M
+
+  Mares' milk, 24
+
+  Matzoon, 15, 38, 106
+
+  Maya, 42;
+    Bulgarian, 10
+
+  Maya Bulgare Company's apparatus, 131
+
+  Meeresy, 5
+
+  Metchnikoff, 34, 40, 44, 121, 158, 163
+
+  Micro-organisms, discovery of, 13
+
+  Middle Ages, 13
+
+  Milk-filling apparatus for bottles, 82
+
+  Milk, general properties of, 57;
+    of different animals, 60;
+    supply of the United Kingdom, 69;
+    industry in the United States, 71;
+    management, 74
+
+  Mitscherlich, 17
+
+  Myristin, 51
+
+
+  N
+
+  Neolithic times, 1
+
+  Nikolaiewa, 95
+
+  Nitrogenous constituents of milk, 52
+
+
+  O
+
+  Ojr�n, 106
+
+  Olein, 51
+
+  Oxygala of Pliny, 4
+
+
+  P
+
+  Paleolithic times, 1
+
+  Palmitin, 51
+
+  Pasteur, 14, 78
+
+  Pasteurisation, 78
+
+  Pelouze, 17
+
+  Pilaff of rice, 5
+
+  Pina, 21
+
+  Podowyssowski on keffir, 87
+
+  Preparation, of soured milk, 81;
+    in the house, 125;
+    in the dairy, 139
+
+  Primary cooler, 78
+
+  Proteids, 53
+
+  Pyrenees, 4
+
+
+  R
+
+  Reindeer's milk as soured milk, 8
+
+  Rubruquis, William de, 19
+
+
+  S
+
+  _Saccharomyces cerevisse�_, 90
+
+  _Saccharomyces keffir_, 32, 33, 91, 93, 94
+
+  Sakwaska, 88
+
+  Sale of Food and Drugs Act, 1899, 49
+
+  Scheele, 17
+
+  Scholl on keffir, 91
+
+  Scythians, 18
+
+  Secondary cooler, 79
+
+  Shammar Bedouins, 2
+
+  Sheneena, 2
+
+  Skolotowski on keffir, 86
+
+  Smith, Professor Robertson, 3
+
+  Soured milk, in the house, 125;
+    in the dairy, 139;
+    in health and disease, 151;
+    from impure cultures, 158;
+    use of, 159
+
+  Souring of milk, 47, 54
+
+  Specific gravity of milk, 65
+
+  Stearin, 51
+
+  Steriliser, 148
+
+  _Streptobacilli lebeni_, 39
+
+  _Streptobacillus lebenis_, 111
+
+  _Streptococcus a_, 93, 94
+
+  _Streptococcus acidi lactici_, 95, 96
+
+  _Streptococcus b_, 93, 94
+
+  _Streptococcus lacticus_, 92, 93, 122, 124
+
+  Sugar of milk, 54
+
+  Sugar preparations and the soured-milk bacillus, 137
+
+  Suter-Naef on Swiss koumiss, 26
+
+  Swedish whey cheese, 60
+
+  Swiss hard cheese, 113
+
+  Symptoms of disease, 161
+
+
+  T
+
+  Temperature allowances when testing milk, tables of, 66
+
+  Town's dairy equipment, 80
+
+  Transmission of disease by milk, 72
+
+
+  U
+
+  United Kingdom, milk supply of, 69
+
+  United States, milk industry of, 71
+
+  Urgoutnik, 43
+
+
+  V
+
+  Van Leeuwenhoek, 13
+
+  Variation limits of milk, 49
+
+  Vedas, 1
+
+  "Veronelle" apparatus, 132
+
+  Vina, 21
+
+  Vinous fermentation, 17
+
+
+  W
+
+  Willows Refrigerating Company's apparatus, 144, 145
+
+  Wilson on koumiss, 23
+
+
+  Y
+
+  Yoghourt, 9, 42, 46, 107
+
+  Yoghourt bacillus, 109
+
+
+  Z
+
+  Zakvaska, 42
+
+       *       *       *       *       *
+
+  Putnam's
+  Science Series
+
+
+  1. +The Study of Man.+ By A. C. HADDON.
+
+  2. +The Groundwork of Science.+ By ST. GEORGE MIVART.
+
+  3. +Rivers of North America.+ By ISRAEL C. RUSSELL.
+
+  4. +Earth Sculpture, or; The Origin of Land Forms.+ By JAMES GEIKIE.
+
+  5. +Volcanoes; Their Structure and Significance.+ By T. G. BONNEY.
+
+  6. +Bacteria.+ By GEORGE NEWMAN.
+
+  7. +A Book of Whales.+ By F. E. BEDDARD.
+
+  8. +Comparative Physiology of the Brain, etc.+ By JACQUES LOEB.
+
+  9. +The Stars.+ By SIMON NEWCOMB.
+
+  10. +The Basis of Social Relations.+ By DANIEL G. BRINTON.
+
+  11. +Experiments on Animals.+ By STEPHEN PAGET.
+
+  12. +Infection and Immunity.+ By GEORGE M. STERNBERG.
+
+  13. +Fatigue.+ By A. MOSSO.
+
+  14. +Earthquakes.+ By CLARENCE E. DUTTON.
+
+  15. +The Nature of Man.+ By �LIE METCHNIKOFF.
+
+  16. +Nervous and Mental Hygiene in Health and Disease.+ By AUGUST FOREL.
+
+  17. +The Prolongation of Life.+ By �LIE METCHNIKOFF.
+
+  18. +The Solar System.+ By CHARLES LANE POOR.
+
+  19. +Heredity.+ By J. ARTHUR THOMPSON, M.A.
+
+  20. +Climate.+ By ROBERT DECOURCY WARD.
+
+  21. +Age, Growth, and Death.+ By CHARLES S. MINOT.
+
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+
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+
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+
+  28. +The Origin of Life.+ By H. CHARLTON BASTIAN.
+
+  29. +The Bacillus of Long Life.+ By LOUDON M. DOUGLAS.
+
+  _For list of works in preparation see end of this volume_
+
+       *       *       *       *       *
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+  Complete Catalogue sent
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+
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+
+
+  +2.--The Groundwork of Science.+ A Study of Epistemology. By
+       ST. GEORGE MIVART, F.R.S. 8�, net $1.75.
+
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+  ever put before the public. It will be interesting to all readers, and
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+
+
+  +3.--Rivers of North America.+ A Reading Lesson for Students of Geography
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+
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+  it is instructive."--_Boston Transcript._
+
+
+  +4.--Earth Sculpture; or, The Origin of Land-Forms.+ By JAMES GEIKIE,
+       LL.D., D.C.L., F.R.S., etc., Murchison Professor of Geology
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+
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+  sympathetic touch of a man deeply in love with nature."--_Science._
+
+
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+       Fully illustrated. 8�, net $2.00.
+
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+  but it is uncommonly attractive to the general reader, and is likely
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+  Republican._
+
+
+  +6.--Bacteria+: Especially as they are related to the economy of
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+
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+  that shall be acceptable to the zoologist and the naturalist."--_N. Y.
+  Times._
+
+
+  +8.--Comparative Physiology of the Brain and Comparative Psychology.+
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+
+  +17.--The Prolongation of Life.+ Optimistic Essays. By �LIE
+        METCHNIKOFF, Sub-Director of the Pasteur Institute. Author of
+        "The Nature of Man." etc. 8�, Illustrated Net, $2.50.
+        (By mail, $2.70.) Popular Edition. With an introduction by
+        Prof. CHARLES S. MINOT. Net, $1.75.
+
+  In his new work Professor Metchnikoff expounds at greater length, in
+  the light of additional knowledge gained in the last few years, his
+  main thesis that human life is not only unnaturally short but
+  unnaturally burdened with physical and mental disabilities. He
+  analyzes the causes of these disharmonies and explains his reasons for
+  hoping that they may be counteracted by a rational hygiene.
+
+
+  +18.--The Solar System.+ A Study of Recent Observations. By Prof.
+        CHARLES LANE POOR, Professor of Astronomy in Columbia
+        University. 8�. Illustrated. Net, $2.00.
+
+  The subject is presented in untechnical language and without the use
+  of mathematics. Professor Poor shows by what steps the precise
+  knowledge of to day has been reached and explains the marvellous
+  results of modern methods and modern observations.
+
+
+  +19.--Climate--Considered Especially in Relation to Man.+ By ROBERT
+        DECOURCY WARD, Assistant Professor of Climatology in Harvard
+        University. 8�. Illustrated. Net, $2.00.
+
+  This volume is intended for persons who have not had special training
+  in the technicalities of climatology. Climate covers a wholly
+  different field from that included in the meteorological text-books It
+  handles broad questions of climate in a way which has not been
+  attempted in a single volume The needs of the teacher and student have
+  been kept constantly in mind.
+
+
+  +20.--Heredity.+ By J. ARTHUR THOMSON, M.A., Professor of Natural
+        History in the University of Aberdeen; Author of "The Science of
+        Life," etc. 8�. Illustrated. Net, $3.50.
+
+  The aim of this work is to expound, in a simple manner, the facts of
+  heredity and inheritance as at present known, the general conclusions
+  which have been securely established, and the more important theories
+  which have been formulated.
+
+
+  +21.--Age, Growth, and Death.+ By CHARLES S. MINOT, James Stillman
+        Professor of Comparative Anatomy in Harvard University,
+        President of the Boston Society of Natural History, and Author
+        of "Human Embryology," "A Laboratory Text-book of Embryology,"
+        etc. 8�. Illustrated.
+
+  This volume deals with some of the fundamental problems of biology,
+  and presents series of views (the results of nearly thirty years of
+  study), which the author has correlated for the first time in
+  systematic form.
+
+
+  +22.--The Interpretation of Nature.+ By C. LLOYD MORGAN, LL.D.,
+        F.R.S. Crown 8vo. Net, $1.25.
+
+  Dr Morgan seeks to prove that a belief in purpose as the causal
+  reality of which nature is an expression is not inconsistent with a
+  full and whole-hearted acceptance of the explanations of naturalism.
+
+
+  +23.--Mosquito Life.+ The Habits and Life Cycles of the Known
+        Mosquitoes   of the United States; Methods for their Control;
+        and Keys for Easy Identification of the Species in their Various
+        Stages. An account based on the investigation of the late James
+        William Dupree, Surgeon-General of Louisiana, and upon the
+        original observations by the Writer. By EVELYN GROESBEECK
+        MITCHELL, A.B., M.S. With 64 Illustrations. Crown 8vo.
+        Net, $2.00.
+
+  This volume has been designed to meet the demand of the constantly
+  increasing number of students for a work presenting in compact form
+  the essential facts so far made known by scientific investigation in
+  regard to the different phases of this, as is now conceded, important
+  and highly interesting subject. While aiming to keep within reasonable
+  bounds, that it may be used for work in the field and in the
+  laboratory, no portion of the work has been slighted, or fundamental
+  information omitted, in the endeavor to carry this plan into effect.
+
+
+  +24.--Thinking, Feeling, Doing.+ An Introduction to Mental Science.
+        By E. W. SCRIPTURE, Ph.D., M.D., Assistant Neurologist Columbia
+        University, formerly Director of the Psychological Laboratory at
+        Yale University. 189 Illustrations. 2d Edition, Revised and
+        Enlarged. Crown 8vo. Net, $1.75.
+
+  "The chapters on Time and Action, Reaction Time, Thinking Time,
+  Rhythmic Action, and Power and Will are most interesting. This book
+  should be carefully read by every one who desires to be familiar with
+  the advances made in the study of the mind, which advances, in the
+  last twenty-five years, have been quite as striking and epoch-making
+  as the strides made in the more material lines of knowledge."--_Jour.
+  Amer. Med. Ass'n._, Feb. 22, 1908.
+
+
+  +25.--The World's Gold.+ By L. DE LAUNAY, Professor at the �cole
+        Superieure des Mines. Translated by Orlando Cyprian Williams.
+        With an Introduction by Charles A. Conant, author of "History of
+        Modern Banks of Issue," etc. Crown 8vo. Net, $1.75.
+
+  M. de Launay is a professor of considerable repute not only in France,
+  but among scientists throughout the world. In this work he traces the
+  various uses and phases of gold; first, its geology; secondly, its
+  extraction; thirdly, its economic value.
+
+
+  +26.--The Interpretation of Radium.+ By FREDERICK SODDY, Lecturer
+        in Physical Chemistry in the University of Glasgow. Crown 8vo.
+        With Diagrams. Net, $1.75.
+
+  As the application of the present day interpretation of Radium (that
+  it is an element undergoing spontaneous disintegration) is not
+  confined to the physical sciences, but has a wide and general bearing
+  upon our whole outlook on Nature, Mr. Soddy has presented the subject
+  in non-technical language, so that the ideas involved are within reach
+  of the lay reader. No effort has been spared to get to the root of the
+  matter and to secure accuracy, so that the book should prove
+  serviceable to other fields of science and investigation, as well as
+  to the general public.
+
+
+  +27.--Criminal Man.+ According to the Classification of CESARE
+        LOMBROSO. Briefly Summarized by his Daughter, Gina Lombroso
+        Ferrero. With 36 Illustrations and a Bibliography of Lombroso's
+        Publications on the Subject. Crown 8vo. Net, $2.00.
+
+  Signora Guglielmo Ferrero's r�sum� of her father's work on criminal
+  anthropology is specially dedicated to all those whose office it is to
+  correct, reform, and punish the criminal, with a view to diminishing
+  the injury caused to society by his anti-social acts; also to
+  superintendents, teachers, and those engaged in rescuing orphans and
+  children of vicious habits, as a guide in checking the development of
+  evil germs and eliminating incorrigible subjects whose example is a
+  source of corruption to others.
+
+       *       *       *       *       *
+
+  The most valuable production since Darwin's "Origin of Species."
+
+  The Nature of Man
+
+  _Studies in Optimistic Philosophy_
+
+  By �lie Metchnikoff
+
+  Sub-Director of the Pasteur Institute, Paris
+
+  Translated with an Introduction by
+
+  P. Chambers Mitchell
+
+  Secretary of the Zo�logical Society
+
+  Octavo. Illustrated. Popular Edition. $1.50 net. By mail, $1.65
+
+  It is not often that a scientific book may be read with ease, profit,
+  and pleasure by the general reader, so that M. Metchnikoff's book
+  comes in the nature of an agreeable surprise. It is marked by a
+  refreshing _na�vet�_ and a large simplicity which are
+  characteristically Russian. The scientific importance of this work is
+  so great that it is spoken of in England as the most valuable
+  production since Darwin's _Origin of Species_.
+
+  Opinions of the Press
+
+  "An extremely interesting and typical book.... With a distinguished
+  frankness, M. Metchnikoff defines his attitude to our universal
+  prepossessions. It is his theory that the infirmities of age are to be
+  overcome. If there be ground for this conception, humanity is to be
+  profoundly changed and what we call life now, will be the childhood
+  and youth of that longer and larger life."--H. G. WELLS, in _London
+  Speaker_.
+
+  "Undoubtedly a great book (in some quarters it has been hailed as the
+  greatest since Darwin's famous message to the world) and should be
+  read by all intelligent men and women."--_The Nation._
+
+  "A book to be set side by side with Huxley's Essays, whose spirit it
+  carries a step further on the long road towards its goal."--_Mail and
+  Express._
+
+  New York--G. P. Putnam's Sons--London
+
+       *       *       *       *       *
+
+  "_Remarkable for its simple language and clear
+  style.... Bears the stamp of a production of
+  an erudite scientist and a deep thinker._"--Science.
+
+
+  The Prolongation of Life
+
+  Optimistic Essays
+
+  _By_ �lie Metchnikoff
+
+  _Author of "The Nature of Man," etc._
+
+  _8vo. Illustrated Popular Edition. $1.75 net By mail, $1.90_
+
+  M. �lie Metchnikoff is one of those rare scientists who have found a
+  way to lay hold of and present to the world in untechnical
+  phraseology, intelligible to the lay mind, such results of his
+  researches as are of universal interest and go straight home to the
+  bosoms and business of intelligent men. _The Nature of Man_, by the
+  same author, was one of the most fascinating books, at once popular,
+  and scientific, which have appeared for decades. The book here in
+  question will stand beside it as a worthy companion volume. It is
+  satisfactory to report that, absorbed as Metchnikoff is in "material"
+  problems, and deep as he is in the mysteries of the physical universe,
+  these essays show him to be an optimist who speaks with no uncertain
+  voice.
+
+  A great deal of attention is given in _The Prolongation of Human Life_
+  to the subject of old age and its causes, with scientific observations
+  of special cases among human beings and the lower animals. The author
+  suggests means of prolonging life and health, while contemplating
+  natural death with serenity, and finding that agreeable sensations
+  accompany its approach. Beyond a certain point it seems to him a
+  disadvantage to prolong life. Passing on from these mortuary
+  lucubrations, the essays concern themselves with psychological
+  matters, with optimism and pessimism and in general with questions of
+  science and morals. The temperaments of certain great men are analyzed
+  in studies that have for their subjects respectively Byron, Leopardi,
+  Schopenhauer, and Goethe. In the preface the author says that he has
+  avoided, as far as possible, repeating points which have been
+  sufficiently treated in _The Nature of Man_.
+
+
+  G. P. PUTNAM'S SONS
+
+  NEW YORK     LONDON
+
+
+
+
+
+End of Project Gutenberg's The Bacillus of Long Life, by Loudon Douglas
+
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+<pre>
+
+The Project Gutenberg EBook of The Bacillus of Long Life, by Loudon Douglas
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: The Bacillus of Long Life
+       a manual of the preparation and souring of milk for dietary
+              purposes, together with and historical account of the use
+              of fermente
+
+Author: Loudon Douglas
+
+Release Date: March 18, 2010 [EBook #31691]
+
+Language: English
+
+Character set encoding: UTF-8
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE BACILLUS OF LONG LIFE ***
+
+
+
+
+Produced by Peter Vachuska, Turgut Dincer, Chuck Greif and
+the Online Distributed Proofreading Team at
+https://www.pgdp.net
+
+
+
+
+
+
+</pre>
+
+
+<h6><a href="#putnam">Putnam's<br />
+Science&nbsp;Series</a></h6>
+
+
+<div class="figcenter" style="width: 500px;"><a name="frontis" id="frontis"></a><img src="images/frontis.jpg" width="500" height="710" alt="The Oldest Woman in the World and her Son"
+title="" />
+
+<p class="caption"><span class="smcap">The Oldest Woman in the World and her Son</span></p>
+
+<p class="indent2">Baba Vasilka is 126 years old, and her son Tudor is 101. They are peasants,
+and have lived all their lives in a little village in Bulgaria. They are
+typical examples of people who live to a great age by the use of soured
+milk, as it has been their principal food all their lives.</p></div>
+
+<h1>The<br />
+Bacillus of Long Life</h1>
+
+<h4>A Manual of the Preparation and Souring of Milk for<br />
+Dietary Purposes, Together with an Historical<br />
+Account of the Use of Fermented Milks, from<br />
+the Earliest Times to the Present Day,<br />
+and Their Wonderful Effect in the<br />
+Prolonging of Human Existence</h4>
+
+<h5>By</h5>
+<h3>Loudon M. Douglas, F.R.S.E.</h3>
+
+<h5><i>With 62 Illustrations</i></h5>
+
+<h4>
+G. P. Putnam's Sons<br />
+<small>New York and London<br />
+The Knickerbocker Press<br />
+1911</small>
+</h4>
+
+<h5><i>Revised Edition</i></h5>
+<hr />
+<h6>
+<span class="smcap">Copyright, 1911</span><br />
+BY<br />
+G. P. PUTNAM'S SONS<br />
+</h6>
+
+<h6>The Knickerbocker Press, New York</h6>
+<hr />
+
+<p><span class='pagenum'><a name="Page_iii" id="Page_iii">iii</a></span></p>
+
+<h4>PREFACE</h4>
+
+<p>This book has been designed with a view to meet
+an extensive demand for definite data on the subject
+of Soured Milks. The author has had this
+matter brought before him, times without number,
+by those inquiring for authentic information on the
+subject, and he has therefore considered it desirable
+to gather together such information as is
+available in connection with ancient and modern
+practice. He has endeavoured to present this to
+the reader in concise form.</p>
+
+<p>The author is indebted to many friends for their
+assistance in getting the book together, and would
+specially mention Dr. H. B. Hutchinson, Bacteriologist,
+Rothamsted Experimental Station, for
+assistance in connection with the bacteriology of
+fermented milks; Mr. Thomas Douglas, of Wimbledon,
+who has assisted with the chemistry of the
+subject; Mr. S. Javrilovitch, of Belgrade, Servia,
+for local information and illustrations; Dr. Otokar
+Laxa, Bacteriologist, of Prague, Bohemia, for
+general assistance; the editor of <i>Bacteriotherapy</i>,
+New York, U.S.A., for the use of the group of
+illustrations 30-44; the publishers of the <i>Centralblatt
+f&uuml;r Bakteriologie</i>, Jena, for the group of illustrations
+14-29; and many others, some of whom
+are referred to in the text.</p>
+<p><span class='pagenum'><a name="Page_iv" id="Page_iv">iv</a></span></p>
+<hr />
+<p><span class='pagenum'><a name="Page_v" id="Page_v">v</a></span></p>
+
+<h4>CONTENTS</h4>
+
+<table width="100%" summary="TOC" border="0">
+<tr>
+<td class="toc15"><small>CHAPTER</small></td>
+<td class="toc75">&nbsp;</td>
+<td class="toc10"><small>PAGE</small></td>
+</tr>
+<tr>
+<td class="toc15">I.&mdash;</td>
+<td class="toc75"><span class="smcap">Introductory&mdash;Historical</span></td>
+<td class="toc10"><a href="#Page_1">1</a></td>
+</tr>
+<tr>
+<td class="toc15">II.&mdash;</td>
+<td class="toc75"><span class="smcap">Fermented Milks</span></td>
+<td class="toc10"><a href="#Page_15">15</a></td>
+</tr>
+<tr>
+<td class="toc15">III.&mdash;</td>
+<td class="toc75"><span class="smcap">The Chemistry of Milk</span></td>
+<td class="toc10"><a href="#Page_47">47</a></td>
+</tr>
+<tr>
+<td class="toc15">IV.&mdash;</td>
+<td class="toc75"><span class="smcap">Handling of Milk</span></td>
+<td class="toc10"><a href="#Page_68">68</a></td>
+</tr>
+<tr>
+<td class="toc15">V.&mdash;</td>
+<td class="toc75"><span class="smcap">The Bacteriology of Fermented or Soured Milk</span></td>
+<td class="toc10"><a href="#Page_84">84</a></td>
+</tr>
+<tr>
+<td class="toc15">VI.&mdash;</td>
+<td class="toc75"><span class="smcap">The Preparation of Soured Milk in the House</span></td>
+<td class="toc10"><a href="#Page_125">125</a></td>
+</tr>
+<tr>
+<td class="toc15">VII.&mdash;</td>
+<td class="toc75"><span class="smcap">The Preparation of Soured Milk in the Dairy</span></td>
+<td class="toc10"><a href="#Page_139">139</a></td>
+</tr>
+<tr>
+<td class="toc15">VIII.&mdash;</td>
+<td class="toc75"><span class="smcap">Soured Milk in Health and Disease</span></td>
+<td class="toc10"><a href="#Page_151">151</a></td>
+</tr>
+<tr>
+<td class="toc15">&nbsp;</td>
+<td class="toc75"><span class="smcap">Index</span></td>
+<td class="toc10"><a href="#Page_165">165</a></td>
+</tr>
+</table>
+
+<p><span class='pagenum'>vi</span></p>
+<hr />
+
+<p><span class='pagenum'>vii</span></p>
+
+<h4>ILLUSTRATIONS</h4>
+
+<table width="100%" summary="TOC" border="0">
+<tr>
+<td class="toc15"><small>FIG.</small></td>
+<td class="toc75">&nbsp;</td>
+<td class="toc10"><small>PAGE</small></td>
+</tr>
+<tr>
+<td class="toc15">&nbsp;</td>
+<td class="toc75j"><p class="indent"><span class="smcap">The Oldest Woman in the World and her Son
+</span></p></td>
+<td class="toc10"><i><a href="#frontis">frontispiece</a></i></td>
+</tr>
+<tr>
+<td class="toc15">&nbsp;</td>
+<td class="toc75"><p class="indent"><span class="smcap">The Pass of Bukova</span></p></td>
+<td class="toc10"><a href="#bukova">2</a></td>
+</tr>
+<tr>
+<td class="toc15">&nbsp;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Kabyles Souring Milk</span></p></td>
+<td class="toc10"><a href="#kabyles">4</a></td>
+</tr>
+<tr>
+<td class="toc15">&nbsp;</td>
+<td class="toc75"><p class="indent"><span class="smcap">The Handling of Milk in the Pyrenees</span></p></td>
+<td class="toc10"><a href="#pyrenees">8</a></td>
+</tr>
+<tr>
+<td class="toc15">&nbsp;</td>
+<td class="toc75"><p class="indent"><span class="smcap">The Constituents of Milk</span></p></td>
+<td class="toc10"><a href="#constituents">48</a></td>
+</tr>
+<tr>
+<td class="toc15">1.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Micro-Photograph of a Drop of Whole Milk</span></p></td>
+<td class="toc10"><a href="#fig1">58</a></td>
+</tr>
+<tr>
+<td class="toc15">2.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Micro-Photograph of Separated Milk</span></p></td>
+<td class="toc10"><a href="#fig2">58</a></td>
+</tr>
+<tr>
+<td class="toc15">3.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Micro-Photograph of Cream</span></p></td>
+<td class="toc10"><a href="#fig3">58</a></td>
+</tr>
+<tr>
+<td class="toc15">4.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photograph of Two Petri Dishes, which have been Inoculated with Ordinary Milk</span></p></td>
+<td class="toc10"><a href="#fig4a">60</a></td>
+</tr>
+<tr>
+<td class="toc15">5.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">The Creamometer</span></p></td>
+<td class="toc10"><a href="#fig5">62</a></td>
+</tr>
+<tr>
+<td class="toc15">6.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Testing-Glass for Extraneous Matter in Milk</span></p></td>
+<td class="toc10"><a href="#fig6">62</a></td>
+</tr>
+<tr>
+<td class="toc15">7.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Lactometer and Test-Glass</span></p></td>
+<td class="toc10"><a href="#fig7">64</a></td>
+</tr>
+<tr>
+<td class="toc15">8.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Pasteuriser</span></p></td>
+<td class="toc10"><a href="#fig8">78</a></td>
+</tr>
+<tr>
+<td class="toc15">9.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Continuous Apparatus for the Production of Large Quantities of Soured Milk</span></p></td>
+<td class="toc10"><a href="#fig9">82</a></td>
+</tr>
+<tr>
+<td class="toc15">10.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">A Milk-Filling Apparatus</span></p></td>
+<td class="toc10"><a href="#fig10">90</a></td>
+</tr>
+<tr>
+<td class="toc15">11.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Section through a Kephir Grain</span></p></td>
+<td class="toc10"><a href="#fig11">94</a></td>
+</tr>
+<tr>
+<td class="toc15">12.&mdash;</td>
+<td class="toc75"><p class="indent"><i>Streptococcus lacticus</i><span class="smcap"> (Grotenfeldt) Growing on Lactose-Agar, Stained by Gram's Method</span></p></td>
+<td class="toc10"><a href="#fig12">96</a></td>
+</tr>
+<tr>
+<td class="toc15">13.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photo-Micrograph of Preparation from Armenian Soured Milk</span></p></td>
+<td class="toc10"><a href="#fig13">106</a></td>
+</tr>
+<tr>
+<td class="toc15">14.&mdash;<span class='pagenum'><a name="Page_viii" id="Page_viii">viii</a></span></td>
+<td class="toc75"><p class="indent"><span class="smcap">Granule Bacillus from Yoghourt. Shredded Preparation of a Fresh Skim-Milk Culture</span></p></td>
+<td class="toc10"><a href="#fig14">110</a></td>
+</tr>
+<tr>
+<td class="toc15">15.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Granule Bacillus from Yoghourt, Cultivated after the Usual Agar Method</span></p></td>
+<td class="toc10"><a href="#fig15">110</a></td>
+</tr>
+<tr>
+<td class="toc15">16.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Granule Bacillus from Yoghourt. Agar Milk Sugar Culture</span></p></td>
+<td class="toc10"><a href="#fig16">110</a></td>
+</tr>
+<tr>
+<td class="toc15">17.&mdash;</td>
+<td class="toc75"><p class="indent"><i>Bacteria W.</i> <span class="smcap">from Milk, Cultivated Twenty-Four Hours</span></p></td>
+<td class="toc10"><a href="#fig17">110</a></td>
+</tr>
+<tr>
+<td class="toc15">18.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Agar Milk Sugar Culture. From the Original Bulgarian Yoghourt</span></p></td>
+<td class="toc10"><a href="#fig18">112</a></td>
+</tr>
+<tr>
+<td class="toc15">19.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Agar Milk Sugar Culture. Surface Colony of Granule Bacillus from Calf's Stomach</span></p></td>
+<td class="toc10"><a href="#fig19">112</a></td>
+</tr>
+<tr>
+<td class="toc15">20.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Agar Milk Sugar Culture. Deep-Lying Colony of Granule Bacillus from Calf's Stomach</span></p></td>
+<td class="toc10"><a href="#fig20">112</a></td>
+</tr>
+<tr>
+<td class="toc15">21.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Agar Milk Sugar. Colony of</span> <i>Bacterium W.</i> <span class="smcap">from Yoghourt</span></p></td>
+<td class="toc10"><a href="#fig21">112</a></td>
+</tr>
+<tr>
+<td class="toc15">22.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Two Colonies of</span> <i>Bacillus Acidophilus</i> <span class="smcap">from Calves' Manure</span></p></td>
+<td class="toc10"><a href="#fig22">114</a></td>
+</tr>
+<tr>
+<td class="toc15">23.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Beer-Wort Gelatine</span></p></td>
+<td class="toc10"><a href="#fig23">114</a></td>
+</tr>
+<tr>
+<td class="toc15">24.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Shredded Preparation of Bulgarian Original Yoghourt</span></p></td>
+<td class="toc10"><a href="#fig24">114</a></td>
+</tr>
+<tr>
+<td class="toc15">25.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Granule Bacillus from Yoghourt. Cultivated in Skim Milk in Twenty-Four Hours</span></p></td>
+<td class="toc10"><a href="#fig25">114</a></td>
+</tr>
+<tr>
+<td class="toc15">26.&mdash;</td>
+<td class="toc75"><p class="indent"><i>Bacteria W.</i>, <span class="smcap">Agar Milk Sugar Culture</span></p></td>
+<td class="toc10"><a href="#fig26">116</a></td>
+</tr>
+<tr>
+<td class="toc15">27.&mdash;</td>
+<td class="toc75"><p class="indent"><i>Bacteria acidophilus</i> <span class="smcap">from Calves' Manure</span></p></td>
+<td class="toc10"><a href="#fig27">116</a></td>
+</tr>
+<tr>
+<td class="toc15">28.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Mucus from Calf's Stomach Inoculated into Milk after Eight Transferrings</span></p></td>
+<td class="toc10"><a href="#fig28">116</a></td>
+</tr>
+<tr>
+<td class="toc15">29.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Diplostreptococcus from Yoghourt. Pure Culture in Skim Milk</span></p></td>
+<td class="toc10"><a href="#fig29">116</a></td>
+</tr>
+<tr>
+<td class="toc15">30.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photo-Micrograph of Preparation Made from Yoghourt, Showing Yeast Cells</span></p></td>
+<td class="toc10"><a href="#fig30">118</a></td>
+</tr>
+<tr>
+<td class="toc15">31.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photo-Micrograph of Smear from Greek Curdled Milk Called "Giaourti"</span></p></td>
+<td class="toc10"><a href="#fig31">118</a></td>
+</tr>
+<tr>
+<td class="toc15">32.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photo-Micrograph of Soured Milk Inoculated with a Tablet containing Viable and Pure Cultures of</span> <i>Bacillus bulgaricus</i></p></td>
+<td class="toc10"><a href="#fig32">120</a></td>
+</tr>
+<tr>
+<td class="toc15">33.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">
+Photo-Micrograph of Milk Inoculated with a Ferment Table in which</span> <i>Bacillus bulgaricus</i> <span class="smcap">is no Longer Viable</span></p></td>
+<td class="toc10"><a href="#fig33">120</a></td>
+</tr>
+<tr>
+<td class="toc15">34.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photo-Micrograph of Smear of Culture of</span> <i>Bacillus bulgaricus</i></p></td><td
+class="toc10"><a href="#fig34">122</a></td>
+</tr>
+<tr>
+<td class="toc15">35.&mdash;</td>
+<td class="toc75"><p class="indent"><i>Bacillus bulgaricus</i>, <span class="smcap">Showing the Cultures in English Cow's Milk</span></p></td>
+<td class="toc10"><a href="#fig35">124</a></td>
+</tr>
+<tr>
+<td class="toc15">36.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photo-Micrograph of Pure Culture of</span> <i>Bacillus bulgaricus</i></p></td>
+<td class="toc10"><a href="#fig36">124</a></td>
+</tr>
+<tr>
+<td class="toc15">37.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photo-Micrograph of Smear of Combined Culture of</span> <i>Bacillus bulgaricus</i> <span class="smcap">and</span> <i>Bacteria paralacticus</i></p></td>
+<td class="toc10"><a href="#fig37">124</a></td>
+</tr>
+<tr>
+<td class="toc15">38.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photo-Micrograph of Smear of One-Month Culture of</span> <i>Bacillus bulgaricus</i></p></td>
+<td class="toc10"><a href="#fig38">126</a></td>
+</tr>
+<tr>
+<td class="toc15">39.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photo-Micrograph of Culture of</span> <i>Bacillus bulgaricus</i> <span class="smcap">in Malt</span></p></td>
+<td class="toc10"><a href="#fig39">126</a></td>
+</tr>
+<tr>
+<td class="toc15">40.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photo-Micrograph of Smear from Milk that had been Allowed to Sour Spontaneously</span></p></td>
+<td class="toc10"><a href="#fig40">126</a></td>
+</tr>
+<tr>
+<td class="toc15">41.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photograph of Agar Culture, Inoculated with a Lactic Powder</span></p></td>
+<td class="toc10"><a href="#fig41">128</a></td>
+</tr>
+<tr>
+<td class="toc15">42.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photograph of Test-Tubes of Sterile Milk, Inoculated with a Tablet Preparation Said to Contain Pure Cultures</span></p></td>
+<td class="toc10"><a href="#fig42">128</a></td>
+</tr>
+<tr>
+<td class="toc15">43.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photograph of Test-Tubes of Sterile Milk, Each Tube having been Inoculated with a Tablet of a Preparation Said to Contain Pure Cultures</span></p></td>
+<td class="toc10"><a href="#fig43">128</a></td>
+</tr>
+<tr>
+<td class="toc15">44.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Photograph of Test-Tubes of Sterile Milk Inoculated with a Tablet of "Lactobacilline"</span></p></td>
+<td class="toc10"><a href="#fig44">130</a></td>
+</tr>
+<tr>
+<td class="toc15"><span class='pagenum'><a name="Page_x" id="Page_x">x</a></span>
+45.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Apparatus of "Le Ferment" Co.</span></p></td>
+<td class="toc10"><a href="#fig45">129</a></td>
+</tr>
+<tr>
+<td class="toc15">46.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Soured Milk Apparatus of the Maya Bulgare Company, Limited</span></p></td>
+<td class="toc10"><a href="#fig46">130</a></td>
+</tr>
+<tr>
+<td class="toc15">47.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Lactic Ferments, Limited, Apparatus</span></p></td>
+<td class="toc10"><a href="#fig47">131</a></td>
+</tr>
+<tr>
+<td class="toc15">48.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Messrs. Allen &amp; Hanbury's Soured Milk Apparatus</span></p></td>
+<td class="toc10"><a href="#fig48">132</a></td>
+</tr>
+<tr>
+<td class="toc15">49.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Vironelle Apparatus for Souring Milk, Made by Messrs. Clay, Paget &amp; Company, Limited</span></p></td>
+<td class="toc10"><a href="#fig49">132</a></td>
+</tr>
+<tr>
+<td class="toc15">50.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">.&mdash;"Lactobator" Made by Messrs. Charles Hearson &amp; Co., Limited</span></p></td>
+<td class="toc10"><a href="#fig50">140</a></td>
+</tr>
+<tr>
+<td class="toc15">51.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Messrs. Hearson &amp; Company's "Lactobator"</span></p></td>
+<td class="toc10"><a href="#fig51">142</a></td>
+</tr>
+<tr>
+<td class="toc15">52.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Edgar's "Lactogenerator," Sold by the Dairy Supply Co., Limited</span></p></td>
+<td class="toc10"><a href="#fig52">143</a></td>
+</tr>
+<tr>
+<td class="toc15">53.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Apparatus of the Willows Refrigerating Co., Limited</span></p></td>
+<td class="toc10"><a href="#fig53">144</a></td>
+</tr>
+<tr>
+<td class="toc15">54.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">"Lacto" Apparatus of the Dairy Outfit Co., Limited</span></p></td>
+<td class="toc10"><a href="#fig54">145</a></td>
+</tr>
+<tr>
+<td class="toc15">55.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Sterilising Apparatus for Sterilising Milk On the Large Scale</span></p></td>
+<td class="toc10"><a href="#fig55">146</a></td>
+</tr>
+<tr>
+<td class="toc15">56.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">Another Method of Sterilising (Dairy Supply Co., Ltd.). An American Apparatus for Preparing Soured Milk</span></p></td>
+<td class="toc10"><a href="#fig56">148</a></td>
+</tr>
+<tr>
+<td class="toc15">57.&mdash;</td>
+<td class="toc75"><p class="indent"><span class="smcap">An American Apparatus for Preparing Soured Milk</span></p></td>
+<td class="toc10"><a href="#fig57">149</a></td>
+</tr>
+</table>
+<hr />
+<p><span class='pagenum'><a name="Page_1" id="Page_1">1</a></span></p>
+
+<h2>THE BACILLUS OF
+LONG LIFE</h2>
+
+
+
+<hr />
+<h4>CHAPTER I</h4>
+
+<h5>INTRODUCTORY&mdash;HISTORICAL</h5>
+
+
+<p>The milk industry is one of the oldest known to
+mankind, and it is difficult to imagine a time when
+milk in one way or another did not form a part of
+the diet of the human race. There is a good deal of
+evidence to show that in Paleolithic and Neolithic
+times, cattle were part of the possessions of the
+nomadic races; and, according to the Vedas, the
+manufacture of butter was known in India 1500
+years <span class="smcap">B.C.</span></p>
+
+<p>In the eastern part of Europe, milk has always
+been looked upon as one of the principal kinds of
+food, but not necessarily the milk of cows, as, from
+ancient times to the present day, the milk from
+<span class='pagenum'><a name="Page_2" id="Page_2">2</a></span>
+camels, buffaloes, sheep, and goats has been used
+indiscriminately throughout the East.</p>
+
+<p>According to Layard,<a name="FNanchor_1" id="FNanchor_1"></a><a href="#Footnote_1" class="fnanchor">1</a> "the Bedouins do not
+make cheese. The milk of their sheep and goats is
+shaken into butter or turned into curds; it is rarely
+or never drunk fresh, new milk being thought very
+unwholesome, as soon by experience I found it to
+be, in the desert. I have frequently had occasion to
+describe the process of making butter by shaking
+the milk in skins. This is also an employment confined
+to women, and one of a very laborious nature.
+The curds are formed by boiling the milk, and then
+putting some curds made on the previous day into
+it and allowing it to stand. When the sheep no
+longer give milk, some curds are dried, to be used as
+a leaven on a future occasion. This preparation,
+called <i>leben</i>, is thick and acid, but very agreeable
+and grateful to the taste in a hot climate. The sour
+milk, or <i>sheneena</i>, a universal beverage amongst
+the Arabs, is either buttermilk pure and diluted, or
+curds mixed with water.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="bukova" id="bukova"></a><img src="images/bukova.jpg" width="500" height="376" alt=
+"The Pass of Bukova."
+title="" />
+
+<p class="indent2"><span class="smcap">The Pass of Bukova.</span>&mdash;During the revolution of 1904, a number of Turkish soldiers, just before traversing
+this pass, were given coffee containing "caf&eacute;" by a Bulgarian coffee-seller, or keeper of a small
+khan. Whilst in the pass the poison began to take effect, and they realized that they had been poisoned.
+Fortunately for them, a peasant with three horses loaded with Yoghourt (soured milk) had taken
+advantage of their escort. The soldiers ate freely of the Yoghourt, which counteracted the effects of
+the poison.</p>
+</div>
+
+<p>"The camel's milk is drunk fresh. It is pleasant
+to the taste, rich, and exceedingly nourishing. It is
+given in large quantities to the horses. The Shammar
+and Aneyza Bedouins have no cows or oxen,
+<span class='pagenum'><a name="Page_3" id="Page_3">3</a></span>those animals being looked upon as the peculiar
+property of tribes who have forgotten their independence,
+and degraded themselves by the cultivation
+of land. The sheep are milked at dawn,
+or even before daybreak, and again in the evening
+on their return from the pastures. The milk is
+immediately turned into leben, or boiled to be
+shaken into butter. Amongst the Bedouins and
+Jebours it is considered derogatory to the character
+of a man to milk a cow or sheep, but not to
+milk the camel. The Sheikhs occasionally obtain
+dates from the cities. They are eaten dry with
+bread and leben, or fried in butter, a very favourite
+dish of the Bedouin...."</p>
+
+
+<p>The practice is now the same as it was in scriptural
+times, when milk was looked upon as the
+principal article of diet, and throughout the Scriptures
+there are copious references to milk in different
+forms, some of which are of peculiar interest at
+the present day.</p>
+
+<p>It may be noticed, for example, that milk is
+absent from the sacred offerings amongst the
+Hebrews, and this was ascribed by the late Professor
+Robertson Smith to the fact that all ferments
+were excluded from presentation at the altar,<a name="FNanchor_2" id="FNanchor_2"></a><a href="#Footnote_2" class="fnanchor">2</a> it
+<span class='pagenum'><a name="Page_4" id="Page_4">4</a></span>being recognised that, owing to the hot climate,
+milk of all kinds became rapidly sour, and in this
+way came to be looked upon as only fit for consumption
+when in that condition. It has been
+suggested that the prohibition referred to is on
+the same level as the prohibition of the use of
+blood, "as milk has sometimes been regarded as a
+kind of equivalent for blood, and containing the
+sacred life."<a name="FNanchor_3" id="FNanchor_3"></a><a href="#Footnote_3" class="fnanchor">3</a> To this day the wandering tribes
+of Arabia consider the milk of their camels and
+flocks more refreshing when it has been slightly
+fermented or soured by being poured into a milk-skin
+on the inside of which are still sticking sour
+clots from the previous milking, and there shaken
+for a brief period; but this slightly soured milk
+(the <i>Oxygala</i> of Pliny) is known widely in the
+East simply as leben (milk). The name is also
+applied to what we term buttermilk.<a name="FNanchor_4" id="FNanchor_4"></a><a href="#Footnote_4" class="fnanchor">4</a></p>
+
+<div class="figcenter" style="width: 500px;"><a name="kabyles" id="kabyles"></a><img src="images/kabyles.jpg" width="500" height="350" alt=
+"Kabyles Souring Milk."
+title="" />
+
+<p class="caption"><span class="smcap">Kabyles Souring Milk</span></p>
+<p class="indent">
+In the north of Africa the use of soured milk is common, and the illustration shows Kabyles shaking a
+skin full of milk so as to sour it. The skin has previously been used for the same operation, and, as
+a consequence, clots of milk are left from the previous day's use, and thus fermentation is set up.
+</p>
+</div>
+
+
+<p><span class='pagenum'><a name="Page_5" id="Page_5">5</a></span></p>
+
+<p>The use of milk-skins for the carrying of milk is
+not confined to one country, as, while it is common
+all over the north of Africa, it is also known in the
+Pyrenees and in some parts of the Balkan Peninsula,
+the object being identical in each case; and
+when it is intended to make butter from the milk,
+the skin is simply rocked between the knees until
+the butter separates, a process of butter-making
+which was also used after the introduction of
+earthenware churns.<a name="FNanchor_5" id="FNanchor_5"></a><a href="#Footnote_5" class="fnanchor">5</a> Dried soured milk is also
+used by the Arabs, and it is reconstituted when
+required by rubbing it up with a little water, and
+it is known as <i>Meeresy</i>.<a name="FNanchor_6" id="FNanchor_6"></a><a href="#Footnote_6" class="fnanchor">6</a> The ordinary soured
+milk is the common article of diet, and is looked
+upon as being necessary at every meal, and travellers
+frequently refer to the use of this product, as
+a few references will show.</p>
+
+<p>Amongst the peasants at the present day, soured
+milk is known as _yoghourt_, a word which is spelt
+differently according to the locality in which it is
+used. The method of preparation is practically the
+same everywhere, and a short description of the
+process as now carried out in one place would, with
+slight modifications, apply to the general method
+adopted all over the East.</p>
+
+<p>Charles G. Addison states: "A supper was
+brought in on a round tray. In the centre was
+a huge pilaff of rice, and around it several small
+dishes of stewed meats, grilled bones, sour clotted
+milk called <i>yaoort</i>,<a name="FNanchor_7" id="FNanchor_7"></a><a href="#Footnote_7" class="fnanchor">7</a> bits of meat roasted, etc....</p>
+
+<p>"We retired into a tent to breakfast, where
+we found an immense bowl of delicious fresh
+camels' milk, with thin hot cakes of unleavened
+bread, baked upon the ashes, ready prepared for
+us. The principal food of the Bedouins consists
+of flour and some camels' milk made into a paste,
+boiled, and eaten swimming in melted grease and
+<span class='pagenum'><a name="Page_6" id="Page_6">6</a></span>butter; boiled wheat and beans dried in the sun and
+prepared with butter are a favourite dish. They
+are all remarkably fond of butter and grease; the
+butter is made in a goat-skin, suspended to
+the tent pole, and constantly shaken about by
+the women."<a name="FNanchor_8" id="FNanchor_8"></a><a href="#Footnote_8" class="fnanchor">8</a></p>
+
+<p>Burckhardt<a name="FNanchor_9" id="FNanchor_9"></a><a href="#Footnote_9" class="fnanchor">9</a> says: "The provisions of my companion
+consisted only of flour; besides flour, I
+carried some butter and dried leben (sour milk),
+which would dissolve in water. It forms not only
+a refreshing beverage, but is much to be recommended
+as a preservative of health when travelling
+in summer. These are our only provisions." With
+regard to the inhabitants of the Houran, Burckhardt
+relates that the most common dishes of these
+people are <i>bourgoul</i> and <i>keshk</i>. "In summer
+they supply the place of the latter by milk, leben,
+and fresh butter. Of the bourgoul I have spoken
+on other occasions; there are two kinds of keshk&mdash;<i>keshk-hammer</i>
+and <i>keshk-leben</i>. The first is prepared
+by putting leaven into the bourgoul and
+pouring water over it. It is then left until almost
+putrid, and afterwards spread out in the sun and
+dried, after which it is pounded, and, when called
+<span class='pagenum'><a name="Page_7" id="Page_7">7</a></span>for, served up mixed with oil or butter. The keshk-leben
+is prepared by putting leben into the bourgoul
+instead of leaven; in other respects the process
+is the same. Keshk and bread are the common
+breakfasts. Towards sunset a plate of bourgoul,
+or some Arab dish, forms the dinner."</p>
+
+<p>Again, Taylor<a name="FNanchor_10" id="FNanchor_10"></a><a href="#Footnote_10" class="fnanchor">10</a> says: "I received a small jug
+of thick buttermilk, not remarkably clean, but
+very refreshing."</p>
+
+<p>These references particularly refer to the East,
+from which it would appear that soured milk was
+universally known in ancient times as it is at the
+present day, and this remark applies not only
+to Egypt, Palestine, and Arabia, but throughout
+Turkey and the Balkan States, where the consumption
+of soured milk is equally common. It
+seems curious that the use of this commodity
+should have been confined for centuries to the
+East, as we shall see later on that its dietetic
+value is so great that it is really a wonderful
+thing that no one has taken the trouble to introduce
+its use to the Western nations until quite
+recently.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="pyrenees" id="pyrenees"></a><img src="images/pyrenees.jpg" width="500" height="498" alt=
+"The Handling OF Milk in the Pyrenees"
+title="" />
+
+<p class="caption"><span class="smcap">The Handling OF Milk in the Pyrenees</span></p>
+<p class="indent">
+The handling of milk in the Pyrenees is, more especially
+in the villages, conducted in goat or sheep skins, in a
+similar way to the methods which prevail in Eastern
+Europe, and the picture shows a skin of milk on a small
+farm in the Pyrenees. The churning is very often performed
+by simply rocking the skin between the knees, acidity
+being induced by remnants of the previous day's milk;
+souring of milk is induced by the same method.</p></div>
+
+<p>A curious example of how the virtues of such
+an article may be independently discovered by
+<span class='pagenum'><a name="Page_8" id="Page_8">8</a></span>another nation is to be found in Lapland, where
+reindeer's milk is the article used. "The reindeer's
+milk," says Acerbi,<a name="FNanchor_11" id="FNanchor_11"></a><a href="#Footnote_11" class="fnanchor">11</a> "constitutes a principal part
+of the Laplander's food, and he has two methods
+of preparing it, according to the season. In summer
+he boils the milk with sorrel till it arrives
+to a consistence; in this manner he preserves it
+for use during that short season. In winter the
+following is his method of preparation: The milk,
+which he collects in autumn till the beginning
+of November, from the reindeer, is put into casks,
+or whatever vessels he has, in which it soon turns
+sour, and, as the cold weather comes on, freezes,
+and in this state it is kept. The milk collected
+after this time is mixed with cranberries and put
+into the paunch of the reindeer, well cleaned
+from filth; thus the milk soon congeals, and it
+is cut out in slices, together with the paunch, to
+effect which a hatchet is used, for no smaller
+instrument would perform the office of dividing
+that lump of ice. It is then separated into small
+pieces and eaten throughout the winter every day
+at noon, which is the Laplander's dinner-hour. It
+must be presumed, as it is served up without
+<span class='pagenum'><a name="Page_9" id="Page_9">9</a></span>
+being brought to the fire, that this is ice-cream in
+the greatest perfection: here are flesh and fruit
+blended with the richest butyraceous milk that can
+be drawn from any animal; but, notwithstanding
+the extraordinary fatness, which may be supposed
+to resist in a great degree the effect of cold, this
+preparation, as our good missionary remarks with
+a degree of feeling, as if his teeth still chattered
+whilst he delivered the account, chills and freezes
+the mouth in a violent manner whenever it is
+taken. The milk which is drawn late in the
+winter freezes immediately after being drawn.
+This is put into small vessels made of birchwood,
+and is considered by the Laplander as such an
+extraordinary delicacy, that he reserves it as the
+most acceptable present he can offer even a missionary.
+It is placed before the fire and eaten
+with a spoon as it is thawed. When put by, it
+is carefully covered up, because if the cold air gets
+to it afterwards, it turns of a yellow colour and
+becomes rancid."</p>
+
+<p>Amongst the peasants at the present day, soured
+milk is known as <i>yoghourt</i>, a word which is spelt
+differently according to the locality in which it is
+used. The method of preparation is practically the
+same everywhere, and a short description of the
+<span class='pagenum'><a name="Page_10" id="Page_10">10</a></span>
+process as now carried out in one place would, with
+slight modifications, apply to the general method
+adopted all over the East.</p>
+
+<p>"The culture," says a correspondent at Varna,
+"which is used for the preparation of yogourt, is
+known as 'Maya' or as 'Bulgarian Maya.' The
+milk which is to be converted into yogourt must
+first be freed from all bacteria by boiling and allowed
+to cool to the temperature of 45&deg; C.; it is then
+inoculated with maya and maintained at an even
+temperature of 45&deg; C. during several hours. There
+are two kinds of maya, or ferment, one known as
+sour, and the other as sweet maya.</p>
+
+<p>"In Europe small stoves, made expressly for the
+purpose, are used to maintain the milk at the
+proper temperature. In this country, however,
+after the milk has been boiled, it is merely poured
+into a bowl and allowed to cool to approximately
+45&deg; C., then a tablespoonful of this tepid milk
+is well mixed (in a small bowl apart) with a similar
+quantity of maya, and the mixture, when it has
+become quite homogeneous, is added to the bowl
+of tepid milk and stirred slightly. (One tablespoonful
+of maya is sufficient to ferment one litre
+of milk.) A cover is then placed on the bowl
+and the whole is enveloped in flannel and left in
+<span class='pagenum'><a name="Page_11" id="Page_11">11</a></span>
+a warm place for three hours in summer, and
+somewhat longer in winter.</p>
+
+<p>"The process of preparation is complete when
+the mixture assumes the appearance of a soft mass
+somewhat resembling cream cheese, but less solid.
+The flannel is then removed, the bowl uncovered
+and placed in a cool spot until needed for consumption.
+Of the yogourt thus prepared, a
+tablespoonful is kept to serve as maya for the
+following day.</p>
+
+<p>"The best yogourt is prepared from sheep's
+milk, the second quality from buffaloes' milk, and
+the third quality from cows' milk. Yogourt forms
+an almost daily article of diet with the natives in
+this country."<a name="FNanchor_12" id="FNanchor_12"></a><a href="#Footnote_12" class="fnanchor">12</a></p>
+
+<p>With regard to the time stated for the fermenting
+process, it must be noted that since the subject has
+been investigated so thoroughly, the time required
+for fermentation has been found to be nearer ten
+than three hours, but this will be dealt with in a
+subsequent chapter.</p>
+
+<p>Historically it may be gleaned from the fragmentary
+references which we have given, that
+soured milk has, from time immemorial, formed
+<span class='pagenum'><a name="Page_12" id="Page_12">12</a></span>
+the principal article of diet of a great many
+peoples, and the notable feature in connection
+with it is, that in some countries where it is in daily
+use, the age limit for human beings seems to be
+very much extended, and it would appear that
+there is a direct connection between the use of
+soured milk and longevity. In Bulgaria, for
+example, it is stated that the majority of the
+natives live to an age considerably in excess of
+what is recognised as the term of life amongst
+Western nations, and inquiry has shown that
+in the eastern part of Southern Europe, amongst
+a population of about three millions, there were
+more than three thousand centenarians found
+performing duties which would not be assigned
+to a man of sixty-five years of age elsewhere. It
+is quite common to find amongst the peasants
+who live to such a large extent upon soured milk,
+individuals of 110 and 120 years of age.<a name="FNanchor_13" id="FNanchor_13"></a><a href="#Footnote_13" class="fnanchor">13</a></p>
+
+<p>In the ancient dairy practice, as we have seen,
+soured milk was the principal product, and the
+extraordinary ages which are recorded of the patriarchs,
+if translated into the modern denomination,
+would not appear to be so imaginary after all,
+<span class='pagenum'><a name="Page_13" id="Page_13">13</a></span>when it is considered that we have thousands of
+examples at the present day of men and women
+enjoying quite as long a term of existence. It has
+been noticed also, that while these very old people
+are able to perform a certain amount of manual
+labour, there is not the same tendency to the
+mental decay which is so prominent and sad a
+feature amongst Western nations, at a period of
+about seventy or eighty years of age. It would
+seem, indeed, as if the habit of living long was well
+known in ancient times, and that, like many other
+of the valuable arts and sciences, it fell under a
+cloud during the Middle Ages, or, perhaps, the
+significance of the use of soured milk fell into
+neglect, and, even after the revival of letters in
+the sixteenth century, still remained obscure.</p>
+
+<p>The discovery of micro-organisms in perishable
+products, which is attributable to Anthony Van
+Leeuwenhoek, a Dutchman, whose vocation was
+the polishing of lenses, and who lived between
+1632 and 1723, altered our point of view, not only
+of disease, but of all the functions carried on by
+the lower organisms. Since Van Leeuwenhoek's
+time, the germ theory has grown to vast proportions
+and has more especially been applied with
+splendid results to the study of milk. As we shall
+<span class='pagenum'><a name="Page_14" id="Page_14">14</a></span>
+see later, the researches of modern investigators
+have led them to the conclusion that micro-organisms
+play such an important part in the milk
+supply, that it is impossible to carry it on safely
+without a knowledge of the bacteriology of the
+subject. This view began to prevail about 1890,
+some twenty years after Pasteur had shown what
+fermentation really meant. Since that time, the
+progress in dairying has been continuous, and,
+during recent years, attention has been directed to
+soured milk to such an extent that it has become
+necessary for all who are interested in the handling
+of milk and milk products to have a knowledge of
+the subject, as it seems clearly demonstrated that,
+under proper direction, there is every possibility of
+its forming an important element in the prolongation
+of life.</p>
+
+<hr />
+<p><span class='pagenum'><a name="Page_15" id="Page_15">15</a></span></p>
+
+
+<h4>CHAPTER II</h4>
+
+<h5>FERMENTED MILKS</h5>
+
+
+<p>There is considerable variety in the number of
+soured or fermented milks, and they are known by
+various names, such as Koumiss or Koomiss, which
+is prepared from mares' milk; Keffir, which was
+originally discovered in the mountains of the Caucasus,
+and which is prepared with Keffir grains;
+Leben, an Egyptian product prepared from the
+milk of the buffalo, cow, or goat; Matzoon, a
+soured milk which is prepared in Armenia from
+ordinary cows' milk; Dadhi, an Indian preparation
+from cows' milk. All of these owe their special
+characteristics to the fact of their having undergone
+lactic and alcoholic fermentation.</p>
+
+<p>"Milk left to itself," says Blyth,<a name="FNanchor_14" id="FNanchor_14"></a><a href="#Footnote_14" class="fnanchor">14</a> "at all temperatures
+above 90&deg; F. begins to evolve carbon
+dioxide, and this is simply a sign and result of
+fermentation. If this fermentation is arrested
+<span class='pagenum'><a name="Page_16" id="Page_16">16</a></span>or prevented, the fluid remains perfectly sweet and
+good for an indefinite time. Besides the production
+of carbon dioxide during decomposition,
+a certain portion of milk sugar is converted into
+lactic acid, some of the casein and albumen are
+broken up into simpler constituents, and a small
+proportion of alcohol produced, which by oxidation
+appears as acetic acid, while the fat is in part
+separated into free fatty acids, which ultimately
+unite with the ammonia produced by the breaking
+up of the albuminoids. The main fermentation
+of milk is a special kind which of late years has
+been much studied, and is known as <i>lactic fermentation</i>.
+Accompanying lactic fermentation there
+is nearly always a weak butyric and a weak
+alcoholic fermentation."</p>
+
+<p>One of the organisms causing <i>Butyric Acid
+Fermentation</i> is a bacillus 3 to 10&micro; in length, and
+about 1&micro; in breadth. It has power of movement,
+and when cultivated in gelatine, liquefies the gelatine,
+forming a scum on the surface. When the
+bacillus is sown into sterile milk, the following,
+according to Hueppe, are the changes:</p>
+
+<p>"If the milk thus infected is incubated, on the
+second day a clear, slightly yellow fluid is seen
+under the layer of cream; this fluid increases from
+<span class='pagenum'><a name="Page_17" id="Page_17">17</a></span>
+day to day, so that gradually a column of fluid
+is formed which is quite clear above, but below is
+turbid; the casein, at first thrown down in a firm
+coagulum, in the course of eight days begins to be
+attacked, and by the end of two or three weeks
+most of it is dissolved. The filtered fluid gives
+the biuret reaction; it contains leucin, tyrosin, and
+ammonia; hence it is clear that the ferment acts
+to some extent as a digestive of albumen. In advanced
+butyric acid fermentation, the fluid is most
+offensive, and may have an alkaline reaction."</p>
+
+<p>Lactic acid was first isolated by Scheele in 1780
+from soured milk, but its exact constitution was
+not determined until later by Liebig, Mitscherlich,
+Gay-Lussac, and Pelouze: "It is widely distributed
+in nature, occurring in the sap of the vine and in
+most fermented liquids, especially in soured milk;
+it is not, however, present in fresh milk."<a name="FNanchor_15" id="FNanchor_15"></a><a href="#Footnote_15" class="fnanchor">15</a></p>
+
+
+<p>In all the Eastern preparations referred to, the
+lactic fermentation is produced, followed by alcoholic
+fermentation, which is due to the slow decomposition
+of the milk sugar, the vinous fermentation
+being most readily set up in milks which contain a
+larger relative proportion of milk sugar and water,
+such as the milk derived from the mare, the sheep,
+<span class='pagenum'><a name="Page_18" id="Page_18">18</a></span>and the camel. As these fermented milks have
+different characteristics, it is necessary to the
+thorough understanding of the process of manufacture
+at the present day, to examine them in
+some detail.</p>
+
+<p><i>Koumiss.</i>&mdash;The greatest of all the fermented
+milks is koumiss, and it has been celebrated from
+the most ancient times until the present day, as
+being the principal food of the wandering tribes of
+Khirgiz, Bashkirs, Kalmucks, and Tartars, who
+inhabit the steppes of European Russia and the
+plains of South, Western, and Central Asia.
+According to Carrick, who has written an interesting
+volume on the subject,<a name="FNanchor_16" id="FNanchor_16"></a><a href="#Footnote_16" class="fnanchor">16</a> the nomads who
+inhabit these vast territories are shut up under the
+most miserable circumstances during the winter
+time and at the advent of spring they roam over the
+steppes from morning to night, usually in the saddle.
+The milk yielded at such time by the mares is
+carefully collected, and these nomads consume
+enormous quantities of it in the fermented state,
+this habit having been in existence amongst them
+from time immemorial. It is said that the Scythians,
+<span class='pagenum'><a name="Page_19" id="Page_19">19</a></span>
+long before the Christian era, used fermented
+mares' milk; and there are ornaments in existence
+in Russia, of Scythian origin, which exhibit in
+detail the preparation of koumiss from mares'
+milk. In historical times, the first mention of
+koumiss was in the twelfth century, when it is
+referred to in the Ipatof Chronicles. During the
+thirteenth century William de Rubruquis, a French
+missionary, wrote about his travels in Tartary,
+and he described how he had first become
+acquainted with koumiss, and how he found it
+savoury to the palate. Subsequent to this, however,
+there is very little mention of koumiss in
+Russian history, or, for that matter, in any other,
+and the first really scientific contribution on the
+subject was by Dr. John Grieve, who was a surgeon
+in the Russian army, and who in the year
+1784 sent a description of koumiss to the Royal
+Society of Edinburgh,<a name="FNanchor_17" id="FNanchor_17"></a><a href="#Footnote_17" class="fnanchor">17</a> of which he was a member,
+and the title of it was, "An Account of the Method
+of Making Wine called by the Tartars Koumiss,
+with Observations on its Use as a Medicine."
+Dr. Grieve strongly advocated the use of
+koumiss as beneficial in cases of wasting diseases,
+and subsequently it was adopted by the medical
+<span class='pagenum'><a name="Page_20" id="Page_20">20</a></span>
+profession, with the result that sanatoria for the
+treatment of pulmonary consumption were established
+at Samara and other places in Russia, and
+met with very great success; and at the present
+day such sanatoria are carried on, but the bacteriology
+of the subject now being thoroughly
+understood, the methods of preparation have been
+somewhat modified.</p>
+
+<p>An interesting account of koumiss is given by
+Clarke,<a name="FNanchor_18" id="FNanchor_18"></a><a href="#Footnote_18" class="fnanchor">18</a> who says:</p>
+
+<p>"Everybody has heard of koumiss, and the
+brandy which the Kalmucks are said to distil from
+the milk of mares. The manner of preparing these
+liquids has been differently related, and perhaps is
+not always the same. They assured us that the
+brandy was merely distilled from buttermilk. The
+milk which they collect overnight is churned in
+the morning into butter; and the buttermilk is
+distilled over a fire made with the dung of their
+cattle, particularly the dromedary, which makes a
+steady and clear fire like peat. But other accounts
+have been given both of the koumiss and the
+brandy. It has been usual to confound them, and
+to consider the koumiss as their appellation for
+the brandy so obtained. By other information I
+<span class='pagenum'><a name="Page_21" id="Page_21">21</a></span>could gain, not only here, but in many other
+camps which we afterwards visited, they are
+different modifications of the same thing although
+different liquors; the koumiss being a kind of
+sour milk, like that so much used by the Laplanders
+called <i>pina</i>, and which has undergone, in a certain
+degree, the vinous fermentation; and the brandy
+an ardent spirit obtained from koumiss by distillation.
+In making koumiss they sometimes
+employ the milk of cows, but never if mares' milk
+can be had, as the koumiss from the latter yields
+three times as much brandy as that made from
+cows' milk.</p>
+
+<p>"The manner of preparing the koumiss is, by
+combining one sixth part of warm water with any
+given quantity of warm mares' milk. To these they
+add, as a leaven, a little old koumiss, and agitate
+the mass till fermentation ensues. To produce
+the vinous fermentation, artificial heat and more
+agitation is sometimes necessary. This affords
+what is called koumiss. The subsequent process
+of distillation afterwards obtains an ardent spirit
+from the koumiss. They call it <i>vina</i>. In their
+own language it bears the very remarkable appellation
+of <i>rack</i> and <i>racky</i>, doubtless nearly allied
+to the names of our East India spirit <i>rack</i> and
+<span class='pagenum'><a name="Page_22" id="Page_22">22</a></span>
+<i>arrack</i>. We brought away a quart bottle of it,
+and considered it very weak bad brandy, not
+unlike the common spirit distilled by the Swedes
+and other northern nations. Some of their women
+were busy making it in an adjoining tent. The
+simplicity of the operation and their machinery
+was very characteristic of the antiquity of this
+chemical process. Their still was constructed of
+mud, or very coarse clay; and for the neck of the
+retort they employed a cane. The receiver of
+the still was entirely covered by a coating of wet
+clay. The brandy had already passed over.
+The woman who had the management of the distillery,
+wishing to give us a taste of the spirit,
+thrust a stick, with a small tuft of camel's hair at its
+end, through the external covering of clay, and
+thus collecting a small quantity of the brandy,
+she drew out the stick, dropped a portion on the
+retort, and, waving the instrument above her head,
+scattered the remaining liquor in the air. I asked
+the meaning of this ceremony, and was answered
+that it is a religious custom to give always the first
+drop of the brandy which they draw from the
+receiver to their God. The stick having been
+plunged into the receiver again, she squeezed it
+into the palm of her dirty and greasy hand, and
+<span class='pagenum'><a name="Page_23" id="Page_23">23</a></span>
+after tasting the liquor, presented it to our lips."</p>
+
+<p>Another interesting account of the preparation
+of koumiss is given by John M. Wilson in the
+<i>Rural Encyclop&aelig;dia</i>,<a name="FNanchor_19" id="FNanchor_19"></a><a href="#Footnote_19" class="fnanchor">19</a> and it shows that the methods
+in use about the middle of last century did not
+differ materially from those which existed centuries
+before.</p>
+
+<p>Wilson says: "Khoumese is vinously fermented
+mares' milk. Any quantity of fresh mares' milk
+is put into wooden vessels; a sixth part of water
+just off the boil is mixed with it; an eighth part of
+old khoumese or of the sourest possible cows' milk
+is added; the mixture is kept from fifteen to twenty-four
+hours, covered up with several folds of coarse
+linen cloth and with a very thick board, and without
+being stirred or in any degree disturbed, in a
+moderately warm place till it becomes thoroughly
+sour, and sends up a thick mass to its surface; it
+is then beaten and pounded and stirred till the
+curd is not only broken, but so thoroughly mixed
+with the serum as to form a thick liquid; it next
+remains covered and at rest during twenty-four
+hours more, and it is finally put into a common
+butter churn and beaten and blended into a state
+of perfect homogeneity. It is now fit for use;
+<span class='pagenum'><a name="Page_24" id="Page_24">24</a></span>yet it acquires an increase of given properties if
+it be allowed to stand for a few days, and either
+then or now it would, if distilled, yield nearly
+one third of its own bulk of a weak spirit which
+will bear to be rectified. Whenever it is used it
+must be previously so agitated that its component
+parts may be well mixed together, and it may be
+kept either in pans for immediate use or in casks
+for more remote use; and if placed in a cool cellar
+it will remain good during three or four months."</p>
+
+<p>Mares' milk owes its peculiar fitness for making
+koumiss to its containing a large proportion of
+sugar of milk, and readily undergoing the vinous
+fermentation, and it possesses a general medicinal
+reputation among the Tartars similar to that which
+asses' milk has partially acquired in Britain.
+"That mares' milk will undergo vinous fermentation
+and yield a certain quantity of spirit," says
+a writer in the <i>Magazine of Domestic Economy</i>,
+"is not generally known, and it was reserved for a
+nation of demi-savages to render this circumstance
+available as an agent of health, as well as an agreeable
+and nourishing beverage. Every educated
+person, however, has heard that the Tartars drink
+mares' milk, though few know that this milk is
+taken on account of its specific virtues alone, and
+<span class='pagenum'><a name="Page_25" id="Page_25">25</a></span>
+not as a substitute for cows' milk, of which they
+have abundance, and with which they adulterate
+mares' milk when scarce." But the koumiss
+is reputed to be much more medicinal than the
+mares' milk itself; and on account of its being free
+from all tendency to curdle in the stomach, and
+of its possessing most of the nutritive power of
+the milk in combination with native fermented
+spirit, it has been strongly recommended by some
+persons as a remedy for most or all cases of general
+debility, of nervous languor, and even pulmonary
+disease.</p>
+
+<p>"Khoumese is called sometimes <i>koumiss</i> and
+sometimes milk wine."</p>
+
+<p>From these references it will be seen that koumiss
+is an alcoholic drink made by the fermentation
+of mares' milk, but it is also frequently prepared
+from the milk of the camel and cows' milk. It is
+stated that a similar preparation to Russian koumiss
+is made in Switzerland from cows' milk simply
+by the addition of a little sugar and yeast to skim
+milk; "it contains more sugar and less lactic acid
+than Russian koumiss, and on account of the much
+greater proportion of casein contained in cows'
+milk, differs considerably from that prepared from
+mares' milk." Suter-Naef gives the composition
+<span class='pagenum'><a name="Page_26" id="Page_26">26</a></span>
+of a Swiss koumiss<a name="FNanchor_20" id="FNanchor_20"></a><a href="#Footnote_20" class="fnanchor">20</a> manufactured at Davos as
+follows:</p>
+
+<table width="90%" summary="Swiss koumiss" border="0">
+<tr>
+<td class="k45">&nbsp;</td>
+<td class="k20c">In Grams.</td>
+<td class="k20c" colspan="2">Per Litre.</td>
+</tr>
+<tr>
+<td class="k45">&nbsp;</td>
+<td class="k20c">Per cent.</td>
+<td class="k20c" colspan="2">(by weight.)</td>
+</tr>
+<tr>
+<td class="k45">Water</td>
+<td class="k20">90.346&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="k20">1019.64</td>
+<td class="k15c">grams.</td>
+</tr>
+<tr>
+<td class="k45">Alcohol</td>
+<td class="k20">3.210&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="k20">36.23</td>
+<td class="k15c">"</td>
+</tr>
+<tr>
+<td class="k45">Lactic acid</td>
+<td class="k20">0.190&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="k20">2.14</td>
+<td class="k15c">"</td>
+</tr>
+<tr>
+<td class="k45">Sugar</td>
+<td class="k20">2.105&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="k20">23.75</td>
+<td class="k15c">"</td>
+</tr>
+<tr>
+<td class="k45">Albuminates</td>
+<td class="k20">1.860&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="k20">20.99</td>
+<td class="k15c">"</td>
+</tr>
+<tr>
+<td class="k45">Butter</td>
+<td class="k20">1.780&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="k20">20.09</td>
+<td class="k15c">"</td>
+</tr>
+<tr>
+<td class="k45">Inorganic salts</td>
+<td class="k20">0.509&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="k20">5.74</td>
+<td class="k15c">"</td>
+</tr>
+<tr>
+<td class="k45">Free carbonic acid</td>
+<td class="k20">0.177&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="k20">2.00</td>
+<td class="k15c">"</td>
+</tr>
+</table>
+
+<p>The ferments used in the preparation of koumiss
+are stated by Carrick to be of two different kinds,
+artificial and natural.</p>
+
+<p>"Of the natural ferments two have been resorted
+to. One is mentioned by Grieve, which he borrowed
+from the Bashkirs of Orenbourg, and which
+simply consists in the addition of one sixth part of
+water and one eighth of the sourest cows' milk to
+fresh mares' milk; the other has been employed,
+and was, if I mistake not, first recommended by
+Bogoyavlensky. It is a very simple if rather a
+tedious method. New mares' milk, diluted with
+one third its bulk of water, is placed in the <i>saba</i>,<a name="FNanchor_21" id="FNanchor_21"></a><a href="#Footnote_21" class="fnanchor">21</a>
+and while allowed to sour spontaneously, is continually
+<span class='pagenum'><a name="Page_27" id="Page_27">27</a></span>
+beaten up. This milk gradually undergoes
+the vinous fermentation, and in twenty-four
+hours is converted into weak koumiss. The disadvantage
+of this mode of commencing fermentation
+is obvious&mdash;viz., the great waste of time in
+agitation. Hence it is only employed when no
+artificial ferment is obtainable.</p>
+
+<p>"In starting the process of fermentation in
+mares' or any other kind of milk, therefore, an
+artificial ferment is more frequently employed
+than a natural one. The former is used only for
+converting the first portion of milk into koumiss;
+the latter is always resorted to afterwards.</p>
+
+<p>"Of artificial ferments the variety is great, for
+besides all putrefying animal matters which contain
+nitrogen&mdash;such as blood, white of egg, glue,
+and flesh&mdash;certain mineral substances which act
+by souring the milk are also capable of exciting
+fermentation.</p>
+
+<p>"Now, many of the nomads, whose mares either
+give no milk or are not milked in winter, commence
+the preparation of their koumiss in spring by borrowing
+a ferment from the animal, mineral, or
+vegetable kingdom. Thus a mixture of honey and
+flour is the favourite ferment with some races of
+nomads; a piece of fresh horse-skin or tendon is
+<span class='pagenum'><a name="Page_28" id="Page_28">28</a></span>
+preferred by others, while a few resort to old copper
+coins, covered with verdigris, for starting fermentation.
+In the choice of a ferment they are guided
+solely by habit and tradition. As it would be
+useless, almost impossible, to give a list of all the
+foreign substances that have been employed with
+the view of converting mares' milk into koumiss, it
+will be best to consider the simplest artificial ferments,
+and those most generally in use.</p>
+
+<p>"The simplest way is that recommended by
+Bogoyavlensky, and adopted and modified by
+Tchembulatof.<a name="FNanchor_22" id="FNanchor_22"></a><a href="#Footnote_22" class="fnanchor">22</a> It is prepared thus: 'Take a
+quarter of a pound of millet-flour, add water to it,
+and boil it down to the consistence of thick oatmeal
+porridge. Then heat separately, in another
+vessel, eleven pints of milk to boiling-point, and
+allow it to cool down. When its temperature has
+<span class='pagenum'><a name="Page_29" id="Page_29">29</a></span>fallen to 95&deg; F., pour it into a wooden bowl or tub,
+and add the boiled flour to it. The upper and open
+part of the vessel is then covered with a piece of
+coarse linen, and left at rest&mdash;at a temperature of
+about 99&deg; F.&mdash;from twenty-four to forty-eight
+hours. The appearance of small bubbles, which
+keep bursting on the surface of this liquid, combined
+with a vinous or acid odour, prove that the
+ferment is ready. To this fermenting fluid twenty-two
+quarts of new milk are gradually (<i>i.e.</i>, every ten
+minutes) added, and the whole mass is continuously
+beaten up for twelve hours. The temperature during
+stirring should never be higher than 94&deg; F. The
+whole fluid soon begins to ferment, and after twelve
+hours a not unpleasant koumiss is ready. This
+should be filtered through a horse-hair or muslin
+sieve, after which it is fit for drinking. This
+liquid is called weak koumiss; but a limited portion
+of the lactine has undergone the lactuous and
+vinous fermentations, and thus the percentage of
+alcohol is small. Koumiss at an ordinary temperature
+remains weak for twelve hours after it has
+been beaten up, and then gradually passes into
+medium.'"</p>
+
+<p>Curiously enough, the richness of cows' milk in
+fat militates against its being a good raw material
+<span class='pagenum'><a name="Page_30" id="Page_30">30</a></span>
+for the making of koumiss, owing to the production
+of small quantities of butyric acid, which follows
+upon the fermentation, so that it is desirable, if
+koumiss is to be prepared from cows' milk, that
+the fat should be first of all eliminated, so that the
+separated milk will then approximate to the composition
+of mares' milk.</p>
+
+<p>"The chemical changes," says Hutchison,<a name="FNanchor_23" id="FNanchor_23"></a><a href="#Footnote_23" class="fnanchor">23</a>
+"which take place in the milk under the double
+fermentation are not difficult to follow; the lactic
+ferment simply changes part of the sugar into
+lactic acid, the vinous ferment eats up a very small
+part of the proteid of the milk, and, at the same
+time, produces from the sugar a little alcohol and
+a good deal of carbon dioxide; the milk thus
+becomes sour, it effervesces and is weakly alcoholic,
+but the lactic acid causes the casein to be precipitated
+just as it does in the ordinary souring of
+milk, and the casein falls down in flocculi."</p>
+
+<p>As will have been noticed, it is an essential part
+of the process of koumiss-making to keep the milk
+in a state of agitation during the period of fermentation,
+a process which is intended to permit of
+oxygen being taken up by the fermenting fluid,
+while, at the same time, the casein is broken up
+<span class='pagenum'><a name="Page_31" id="Page_31">31</a></span>into a state of fine division. The casein also, or at
+least a portion of it, becomes very soluble, and after
+twelve hours of fermentation the taste of the product
+is only slightly sour, and the milk taste still
+remains. This taste, however, disappears in twenty-four
+hours, owing to the rapid development of the
+lactic acid organisms. After this lapse of time
+the sugar is entirely destroyed, and the strong
+koumiss which results is a thin sour fluid which
+effervesces briskly, and in this condition will keep
+for an indefinite period. "The net change which
+has taken place in the original milk may be summed
+up by saying that the sugar of the milk has been
+replaced by lactic acid, alcohol, and carbon dioxide,
+the casein has been partly precipitated in a state
+of very fine division, and partly pre-digested and
+dissolved, while the fat and salts have been left
+much as they were."<a name="FNanchor_24" id="FNanchor_24"></a><a href="#Footnote_24" class="fnanchor">24</a></p>
+
+<p>Violent stirring or agitation of the cultures does
+not seem to work so much by supplying oxygen to
+the fermenting liquid, as by ensuring a thorough
+distribution of the micro-organisms throughout
+the liquid, and thus dividing the casein.</p>
+
+<p>The greater number of the organisms are facultative
+an&aelig;robes and oxygen is not necessary.
+<span class='pagenum'><a name="Page_32" id="Page_32">32</a></span>Again, koumiss put up in bottles on the first day is
+regularly shaken although air is excluded.</p>
+
+<p><i>Keffir.</i>&mdash;Keffir is a kind of fermented milk which
+has been in use in the Caucasus for quite a long
+time, as koumiss has been in the steppes. It
+differs from koumiss, however, in this respect, that
+it is prepared from either sheep's, goats', or cows'
+milk. The process is started by the addition of
+keffir grains to the milk, which is contained in
+leathern bottles. These keffir grains are small
+solid kernels which are kept in families and handed
+on from one generation to another.<a name="FNanchor_25" id="FNanchor_25"></a><a href="#Footnote_25" class="fnanchor">25</a> The grains
+are the origin of the ferment, as they disseminate
+in the milk micro-organisms of a lactic yeast
+(<i>Saccharomyces kefir</i> Beyerinck and Freudenreich)
+and also the bacillus <i>Bacterium caucasicum</i>, which
+develop rapidly and split up the milk sugar into
+carbon dioxide, alcohol, and lactic acid. Small
+quantities of glycerine, acetic, succinic, and butyric
+acids are also formed, the casein and albumen being
+partly peptonised.<a name="FNanchor_26" id="FNanchor_26"></a><a href="#Footnote_26" class="fnanchor">26</a> Keffir becomes slightly effervescent
+in twenty-four hours, and in that time
+develops a small quantity of alcohol, but after
+three days the amount of alcohol and lactic acid
+<span class='pagenum'><a name="Page_33" id="Page_33">33</a></span>
+is much increased.<a name="FNanchor_27" id="FNanchor_27"></a><a href="#Footnote_27" class="fnanchor">27</a> It has been determined that
+the fermentation of the milk is due to <i>Saccharomyces
+kefir</i>, and that the <i>Lactobacillus Caucasicus</i>
+does not take any part in the fermentation, a fact
+which seems to be supported by the capacity of
+ordinary keffir for starting the fermentation in fresh
+milk in the same manner as the keffir grains. The
+use of this beverage seems to be universal throughout
+the Caucasus, and travellers in these regions
+have frequently referred to it. Thus Freshfield<a name="FNanchor_28" id="FNanchor_28"></a><a href="#Footnote_28" class="fnanchor">28</a>
+states in one part of his book of travels as follows:</p>
+
+<p>"The pig-faced peasant against whom we had
+at first sight conceived such an unjust prejudice
+turned out a capital fellow. He brought us not
+only fresh milk, but a peculiar species of liquor,
+something between public-house beer and sour
+cider, for which we expressed the greatest admiration,
+taking care at the same time privately
+to empty out the vessel containing it, on the first
+opportunity." And again:</p>
+
+<p>"The hospitable shepherds regaled us, not only
+with the inevitable and universal airam or sour
+milk&mdash;if a man cannot reconcile himself to sour
+milk, he is not fit for the Caucasus&mdash;but with a
+<span class='pagenum'><a name="Page_34" id="Page_34">34</a></span>local delicacy that has lately been brought to the
+knowledge of Europe&mdash;kefir. This may best be
+described as 'effervescing milk.' It is obtained by
+putting into the liquid some yellow grains, parts
+of a mushroom which contains a bacillus known to
+science as <i>Dispora caucasia</i>. The action of the
+grains is to decompose the sugar in the milk, and
+to produce carbonic acid and alcohol. The grains
+multiply indefinitely in the milk; when dried they
+can be preserved and kept for future use; its
+results on the digestion are frequently unsatisfactory,
+as one of my companions learnt to his
+cost."</p>
+
+
+<p>"It has been supposed," says Metchnikoff,
+"that the chief merit of kephir was that it was
+more easy to digest than milk, as some of its
+casein is dissolved in the process of fermentation.
+Kephir, in fact, was supposed to be partly digested
+milk. This view has not been confirmed. Professor
+Hayem thinks that the good effects of kephir
+are due to the presence of alcoholic acid, which
+replaces the acid of the stomach and has an antiseptic
+effect. The experiments of M. Rovigh,
+which I speak of in <i>The Nature of Man</i>, have confirmed
+the latter fact, which now may be taken
+as certain. The action of kephir in preventing
+<span class='pagenum'><a name="Page_35" id="Page_35">35</a></span>
+intestinal putrefaction depends on the lactic acid
+bacillus which it contains. Kephir, although in
+some cases certainly beneficial, cannot be recommended
+for the prolonged use necessary, if intestinal
+putrefaction is to be overcome.... Professor
+Hayem prohibits its use in the case of persons in
+whom food is retained for long in the stomach.
+When it is retained in the stomach, kephir goes on
+fermenting, and there are developed in the contents
+butyric and acetic acids, which aggravate the
+digestive disturbances. Kephir is produced by
+combined lactic and alcoholic fermentations ... and
+it is the lactic and not the alcoholic fermentation
+on which the valuable properties of kephir
+depend; it is correct to replace it by sour milk,
+that contains either no alcohol or merely the smallest
+traces of it. The fact that so many races make
+sour milk and use it copiously is an excellent testimony
+of its usefulness."</p>
+
+<p>There are two methods given by Fl&uuml;gge<a name="FNanchor_29" id="FNanchor_29"></a><a href="#Footnote_29" class="fnanchor">29</a> for
+the preparation of keffir:</p>
+
+<p>"In the first, the dry brown kefir grains of
+commerce are allowed to lie in water for five or
+six hours until they swell; they are then carefully
+<span class='pagenum'><a name="Page_36" id="Page_36">36</a></span>washed and placed in fresh milk, which should be
+changed once or twice a day until the grains
+become pure white in colour and when placed in
+fresh milk, quickly mount to the surface&mdash;twenty
+to thirty minutes. One litre of milk is then poured
+into a flask, and a full tablespoonful of the prepared
+<i>k&ouml;rner</i> added to it. This is allowed to stand
+open for five to eight hours; the flask is then closed
+and kept at 18&deg; C. It should be shaken every two
+hours. At the end of twenty-four hours the milk
+is poured through a fine sieve into another flask,
+which must not be more than four fifths full. This
+is corked and allowed to stand, being shaken from
+time to time. At the end of twenty-four hours a
+drink is obtained which contains but little carbon-dioxide
+or alcohol. Usually it is not drunk until
+the second day, when, upon standing, two layers are
+formed, the lower milky, translucent; and the
+upper containing fine flakes of casein. When
+shaken it has a cream-like consistence. On the
+third day it again becomes thin and very acid.
+The second method is used when one has a good
+kefir and two or three days to start with. Three
+or four parts of fresh cows' milk are added to one
+part of this and poured into flasks which are allowed
+to stand for forty-eight hours with occasional
+<span class='pagenum'><a name="Page_37" id="Page_37">37</a></span>
+shaking. When the drink is ready for use, a
+portion (one fifth to one third) is left in the flask
+as ferment for a fresh quantity of milk. The
+temperature should be maintained at about 18&deg;
+C., but at the commencement a higher temperature
+is desirable. The grains should be carefully
+cleaned from time to time and broken up to the
+size of peas. The clean grains may be dried upon
+blotting-paper, in the sun, or in the vicinity of a
+stove; when dried in the air they retain their
+power to germinate for a long time."</p>
+
+<p><i>Leben.</i>&mdash;In our earlier references to fermented
+milks in scriptural times, we observed that alcoholic
+fermented milks were not permitted to be presented
+at the altar. Such offerings, however, were quite
+allowable amongst the ancient Egyptians, the
+Arabs and Carthaginians,<a name="FNanchor_30" id="FNanchor_30"></a><a href="#Footnote_30" class="fnanchor">30</a> and from remote antiquity
+these nations placed great value on this
+product. Leben, which is peculiarly associated
+with Egypt, is a soured milk prepared from the
+milk of buffaloes, cows, or goats. It is usually
+prepared by the boiling of the fresh milk over a slow
+fire, after which some fermented milk from a
+previous preparation is added to the warm article,
+and the fermentation takes place rapidly and is
+<span class='pagenum'><a name="Page_38" id="Page_38">38</a></span>
+considered to be complete in about six hours.<a name="FNanchor_31" id="FNanchor_31"></a><a href="#Footnote_31" class="fnanchor">31</a>
+The Egyptian leben is valued so highly that it is
+offered in hospitality to the passing stranger, and
+it is regarded as so much of a duty to present this
+milk, that in some parts of Arabia it would be
+looked upon as scandalous if any payment were
+received in return.<a name="FNanchor_32" id="FNanchor_32"></a><a href="#Footnote_32" class="fnanchor">32</a></p>
+
+<p><i>Matzoon.</i>&mdash;Matzoon is prepared in Armenia in
+somewhat the same manner as keffir is prepared in
+the Caucasus, and indeed it differs very slightly
+from keffir in composition. Its use is universal in
+Armenia.</p>
+
+<p><i>Dadhi.</i>&mdash;In India large quantities of fermented
+milk are used, under the name of Dadhi, and its
+characteristics are not unlike the similar products
+in Europe. The specific bacillus has been investigated
+by Chatterjee,<a name="FNanchor_33" id="FNanchor_33"></a><a href="#Footnote_33" class="fnanchor">33</a> who concludes that it is
+somewhat akin to the <i>Bacillus bulgaricus</i> and the
+bacillus of leben (<i>B. lebenis</i>). Dr. Chatterjee
+gives a r&eacute;sum&eacute; of his investigations which sums
+up the whole matter thus:</p>
+
+<p>"1. The fermented milk of India called Dadhi
+<span class='pagenum'><a name="Page_39" id="Page_39">39</a></span>
+resembles in all essential points the Bulgarian fermented
+milk as well as the leben and other forms
+of fermented milk in use in the East.</p>
+
+<p>"2. The causative element of the curdling
+process of Dadhi is a streptothrix having characters
+similar to the <i>Bacillus bulgaricus</i> and <i>Streptobacilli
+lebeni</i>, and <i>Bacillus caucasina</i> and the Long Bacilli
+of Mazun, in (1) not growing in ordinary media;
+(2) producing a large amount of lactic acid in milk;
+(3) producing, besides coagulation of casein and
+splitting up the sugar of milk into lactic acid, no
+other change in milk; (4) not producing any indol,
+nor peptone, nor saponification of fat, nor formation
+of any gas.</p>
+
+<p>"3. It differs from the above by showing
+peculiar pink-stained granules, when stained with
+methylene blue and showing peculiarly convoluted
+chains in glucose agar.</p>
+
+<p>"4. The importance of the organism lies in the
+fact that, as in the case of <i>Bacillus bulgaricus</i>, it
+kills all pathogenic non-sporing germs and also
+destroys all proteolytic gas-forming bacilli in
+milk."</p>
+
+<p>In the account of these investigations the following
+table is given, showing the amount of lactic
+acid produced by different lactic acid bacilli in
+<span class='pagenum'><a name="Page_40" id="Page_40">40</a></span>
+one litre of milk, in terms of lactic acid&mdash;the culture
+being kept at 37&deg; C.</p>
+
+<table width="100%" summary="lactic acid" border="0">
+<tr>
+<td class="l25c">Name of<br />the Bacillus</td>
+<td class="l7c">After<br />24<br />Hours</td>
+<td class="l7c">After<br />48<br />Hours</td>
+<td class="l7c">After<br />72<br />Hours</td>
+<td class="l7c">After<br />96<br />Hours</td>
+<td class="l7c">After<br />a<br />Week</td>
+<td class="l40c">Remarks</td>
+</tr>
+<tr>
+<td class="l25">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l40">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="l25"><p class="indent">B.&nbsp;lactis &aelig;rogenes</p></td>
+<td class="l7">1.8</td>
+<td class="l7cc">...</td>
+<td class="l7">10.08</td>
+<td class="l7cc">...</td>
+<td class="l7cc">...</td>
+<td class="l40"><p class="indent">Observed by Hall and Smith</p></td>
+</tr>
+<tr>
+<td class="l25">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l40">&nbsp;</td>
+</tr>
+<tr>
+<td class="l25"><p class="indent">B.&nbsp;coli communis</p></td>
+<td class="l7">1.8</td>
+<td class="l7cc">...</td>
+<td class="l7">4.77</td>
+<td class="l7cc">...</td>
+<td class="l7cc">...</td>
+<td class="l40"><p class="indent">Observed by Hall and Smith</p></td>
+</tr>
+<tr>
+<td class="l25">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l40">&nbsp;</td>
+</tr>
+<tr>
+<td class="l25"><p class="indent">B.&nbsp;Bulgaricus</p></td>
+<td class="l7">12.8<br />-.4</td>
+<td class="l7">16.5<br />-.4</td>
+<td class="l7">20.2<br />-.4</td>
+<td class="l7cc">...<br />...</td>
+<td class="l7">22.0<br />-.4</td>
+<td class="l40"><p class="indent">Observed by Gabriel Bertrand and Weisweller; the initial acidity of the milk was 4.</p></td>
+</tr>
+<tr>
+<td class="l25">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l40">&nbsp;</td>
+</tr>
+<tr>
+<td class="l25"><p class="indent">Matzoon Long st&auml;bschen B.</p></td>
+<td class="l7">10.8</td>
+<td class="l7">12.0</td>
+<td class="l7cc">...</td>
+<td class="l7cc">...</td>
+<td class="l7cc">...</td>
+<td class="l40"><p class="indent">Observed by D&uuml;ggeli</p></td>
+</tr>
+
+<tr>
+<td class="l25">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l40">&nbsp;</td>
+</tr>
+<tr>
+<td class="l25"><p class="indent">Streptobacillus lebenis</p></td>
+<td class="l7">2.61<a name="FNanchor_34" id="FNanchor_34"></a><a href="#Footnote_34" class="fnanchor">34</a></td>
+<td class="l7cc">...</td>
+<td class="l7cc">...</td>
+<td class="l7cc">...</td>
+<td class="l7cc">...</td>
+<td class="l40"><p class="indent">Observed by Rist and Khoury</p></td>
+</tr>
+<tr>
+<td class="l25">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l7cc">&nbsp;</td>
+<td class="l40">&nbsp;</td>
+</tr>
+<tr>
+<td class="l25b"><p class="indent">Streptothrix dadhi<br /><br /></p></td>
+<td class="l7b">10.8<br /><br /></td>
+<td class="l7b">1.08<br /><br /></td>
+<td class="l7b">11.25<br /><br /></td>
+<td class="l7b">11.70<br /><br /></td>
+<td class="l7b">18.5<br /><br /></td>
+<td class="l40b"><p class="indent">Medd. Coll. Calcutta</p><br /></td>
+</tr>
+</table>
+
+<p>In different parts of the world sour milk is
+consumed in great quantities, and it is stated by
+Metchnikoff<a name="FNanchor_35" id="FNanchor_35"></a><a href="#Footnote_35" class="fnanchor">35</a> that the chief food of the natives
+<span class='pagenum'><a name="Page_41" id="Page_41">41</a></span>of tropical Africa consists of soured milk, and in
+Western Africa in the region south of Angola, the
+natives live almost entirely on this product, there
+being a difference in the curdled milks produced
+according to the nature of the microbial flora
+which is introduced.</p>
+
+
+<p>It is stated<a name="FNanchor_36" id="FNanchor_36"></a><a href="#Footnote_36" class="fnanchor">36</a> that in Servia, Bulgaria,<a name="FNanchor_37" id="FNanchor_37"></a><a href="#Footnote_37" class="fnanchor">37</a> and Roumania
+there were 5000 centenarians living in 1896,
+and while many reasons are advanced for such
+an abnormal condition of affairs, it seems fairly
+certain that the sole reason why people in these
+districts live to such great ages is because of their
+mode of living and the fact that they live very
+largely on soured milk. The hygienic conditions
+throughout these countries are not such as would
+give the population in the towns and villages any
+special advantages in the prolongation of life, and
+while it may be stated that a pastoral and agricultural
+life are likely to contribute to longevity,
+these conditions would not account for a general
+tendency to live long in the countries referred to,
+more than in any other agricultural area. There
+are many countries throughout the world in which
+the pastoral and agricultural existence is general,
+<span class='pagenum'><a name="Page_42" id="Page_42">42</a></span>but it has not been shown that in these countries
+life is prolonged. Hence the conclusion has been
+forced upon investigators that the reason is to be
+found not in the pastoral conditions, but in the
+habit which has existed from time immemorial of
+consuming sour milk as a principal article of diet.</p>
+
+<p>There is no curtailment of the use of fermented
+milks in Eastern Europe, and the methods of preparation
+at the present day are those which have
+been carried out from time immemorial. A local
+observer states that in Bulgaria yoghourt is made
+in nearly every household, especially in the spring
+and summer. The method of preparation is very
+simple: The milk is boiled until a quarter of its
+volume has evaporated, it is then cooled to 45&deg; C.
+and the ferment added. This ferment is a portion
+of the yoghourt of good flavour and is called
+"Maya" or "Zakvaska." The vases, a kind of
+earthenware pot, are enveloped in woollen stuff or
+sheepskin and placed in a warm place near the
+chimney. In ten hours the yoghourt is made, and
+it is preserved in a cold place. The great reputation
+that the yoghourt has acquired in Western
+Europe has caused this "Maya" to become an
+article of commerce. It is sent out by rail hermetically
+sealed in tinplate boxes. According to
+<span class='pagenum'><a name="Page_43" id="Page_43">43</a></span>
+a Sophia chemist, the "Maya" is employed in
+the following manner: For a litre of milk it is
+necessary to take about 10 gr. of the ferment.
+This ferment is diluted with three times the
+amount of water and put into a bowl previously
+heated with hot water and dried. Into this bowl
+the milk, previously boiled and cooled to a temperature
+of 75&deg; to 50&deg; C., is poured; it is then
+covered over and put in a temperature of about
+30&deg; C., and, in default of a stove of constant
+temperature, the bowl is wrapped round with
+flannel or a plaid, and left to curdle for eight to
+ten hours. It is then ready for consumption.
+During winter, curdled milk keeps for several
+days, and in summer it becomes sour in from twelve
+to twenty-four hours.</p>
+
+<p>A similar food to the yoghourt is prepared in the
+Balkan mountains from sheep's milk under the
+name of "Urgoutnik."<a name="FNanchor_38" id="FNanchor_38"></a><a href="#Footnote_38" class="fnanchor">38</a> The milk is poured into a
+goatskin or sheepskin bag, and a little of the fermented
+milk added, and is then left for some hours
+in a warm place. The milk consumed is replaced
+by a fresh supply. In some of the Balkan countries,
+they are not content with the fermentation of the
+milk, they add a little alum, which, under the name
+<span class='pagenum'><a name="Page_44" id="Page_44">44</a></span>
+of "typsa," is well known for this purpose. The
+milk attains such a solid consistency that it can
+be put into a cloth and carried to market.<a name="FNanchor_39" id="FNanchor_39"></a><a href="#Footnote_39" class="fnanchor">39</a></p>
+
+<p>The various forms of sour milk which have
+been described in the foregoing pages may be said
+to be of the traditional kind, and with the light
+of modern knowledge, it has been possible to determine
+exactly what constitutes the active principle
+in use in the milk consumed in these countries,
+and, as we shall see, this principle has been applied
+so that, at the present day, a pure fermented
+milk may be obtained in any country, and there
+is every reason to believe that should such be
+adopted as a general article of food, it would contribute
+to the prolongation of human existence.</p>
+
+<p>It is due to Metchnikoff, of the Pasteur Institute,
+that so much prominence has been given to the
+use of fermented milks. He gave it as his opinion<a name="FNanchor_40" id="FNanchor_40"></a><a href="#Footnote_40" class="fnanchor">40</a>
+that senility was caused partly by auto-intoxication
+or by the poison derived from putrefactive
+micro-organisms which inhabit the digestive track.
+These organisms increase with age, and under
+<span class='pagenum'><a name="Page_45" id="Page_45">45</a></span>certain unhealthy conditions multiply enormously,
+particularly in the large intestine. Having arrived
+at this knowledge, Metchnikoff set to work to
+devise some means of combating the influence of
+these harmful microbes, and set up the hypothesis
+that the tendency to longevity which is exhibited
+in Eastern countries is due to the consumption of
+lactic acid organisms in the shape of soured milk.
+These organisms are more powerful than those of
+a putrefactive character and inhibit their growth.</p>
+
+<p>"In the presence of such facts," says Metchnikoff,
+"it becomes exceedingly important to
+find some means of combating the intestinal putrefaction
+which constitutes so incontestable a source
+of danger. Such putrefaction is not only capable
+of producing diseases of the digestive tube&mdash;<i>enteritis</i>
+and <i>colitis</i>&mdash;but even of becoming a source
+of intoxication of the organism in its most varied
+manifestations.</p>
+
+<p>"It is some years since I proposed to combat
+intestinal putrefaction and its injurious consequences
+by means of lactic ferments. I thought
+the acidity produced by such microbes would
+be much more effective in preventing the germination
+of putrefying microbes than the small quantity
+of acids produced by <i>Bacillus coli</i>. On the other
+<span class='pagenum'><a name="Page_46" id="Page_46">46</a></span>
+hand, I had no illusion as to the difficulty sure
+to be encountered in any effort to introduce lactic
+microbes into the intestinal flora which has been
+preoccupied by a multitude of other microbes.
+To make surer of the result, I chose the lactic
+microbe, which is the strongest as an acid producer.
+It is found in the <i>yahourt</i> (yoghourt),
+which originates in Bulgaria. The same bacillus
+has also been isolated from the <i>leben</i> of Egypt; and
+it is now proved that it is found in the curdled milk
+of the whole Balkan peninsula, and even in the
+Don region of Russia."<a name="FNanchor_41" id="FNanchor_41"></a><a href="#Footnote_41" class="fnanchor">41</a></p>
+
+<p>It is a short step from considerations like these
+to the adoption of the <i>Bacillus bulgaricus</i> as the
+most potent of the various lactic organisms which
+have been examined, and which is likely to play
+such an important r&ocirc;le in the destiny of the human
+race. The <i>Bacillus bulgaricus</i> may claim to be
+the Bacillus of Long Life.</p>
+<hr />
+<p><span class='pagenum'><a name="Page_47" id="Page_47">47</a></span></p>
+
+
+<h4>CHAPTER III</h4>
+
+<h5>THE CHEMISTRY OF MILK</h5>
+
+
+<p><i>The Composition of Milk.</i>&mdash;Like all other organic
+substances, or those built up in connection
+with the life processes of plants and animals, milk
+is of complex composition. It is also very liable
+to change&mdash;every one is acquainted with its
+tendency to "go bad." This instability is more or
+less inherent in all highly organised chemical compounds,
+and, indeed, it seems to be necessary that
+the materials used in growth and nutrition should
+be very plastic in a chemical sense, in order, <i>e.g.</i>,
+that the constituents, say of a plant, may easily
+be transformed into the substances of the body
+of the animal which feeds on it.</p>
+
+<p>The perishable nature of milk&mdash;the food of
+young and growing animals&mdash;is therefore essential,
+so that it may be changed easily into the blood,
+bone, muscle, etc., so abundantly required in the
+early stages of existence.</p>
+
+<p><span class='pagenum'><a name="Page_48" id="Page_48">48</a></span>
+Milk is a complete food, and, therefore, naturally
+it is not a simple chemical compound, but a mechanical
+mixture of a number of substances. The
+present state of chemical knowledge on the subject
+does not permit of its composition being given
+in detail, but for practical purposes, such as those of
+measuring its purity and food value, this is not
+necessary.</p>
+
+<p>A proximate analysis, in which, at least, some of
+the ingredients are lumped together, is sufficient,
+and has been adopted everywhere by analysts.
+On this basis the average composition of cows'
+milk may be stated as follows:</p>
+
+<table width="67%" summary="cows milk" border="0">
+<tr>
+<td class="m70">&nbsp;</td>
+<td class="m30">&nbsp;&nbsp;&nbsp;&nbsp;Per&nbsp;cent.</td>
+</tr>
+<tr>
+<td class="m70">Water</td>
+<td class="m30">87.50&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">Fat</td>
+<td class="m30">3.50&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">Casein and albumen</td>
+<td class="m30">3.65&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">Milk sugar</td>
+<td class="m30">4.60&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">Ash</td>
+<td class="m30">0.75&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">&nbsp;</td>
+<td class="m30">&mdash;&mdash;&mdash;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">&nbsp;</td>
+<td class="m30">100.00&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">&nbsp;</td>
+<td class="m30">&mdash;&mdash;&mdash;&nbsp;&nbsp;</td>
+</tr>
+</table>
+
+<p>The constituents other than water added together
+form the "total solids," and they amount to 12.5
+per cent.</p>
+
+<table width="67%" summary="total solids" border="0">
+<tr>
+<td class="m70">&nbsp;</td>
+<td class="m30">Per cent.</td>
+</tr>
+<tr>
+<td class="m70">Water</td>
+<td class="m30">87.50&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">Total solids</td>
+<td class="m30">12.5&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">&nbsp;</td>
+<td class="m30">&mdash;&mdash;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">&nbsp;</td>
+<td class="m30">100.0&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m70">&nbsp;</td>
+<td class="m30">&mdash;&mdash;&nbsp;&nbsp;</td>
+</tr>
+
+</table>
+
+<div class="figcenter" style="width: 500px;"><a name="constituents" id="constituents"></a><img src="images/constituents.jpg" width="500" height="224" alt=
+"The Constituents of Milk"
+title="" />
+
+<p class="caption"><span class="smcap">The Constituents of Milk</span></p>
+
+<p class="indent">In the illustration, a pint of milk is shown in a glass jar, and the various percentages of water, casein, sugar, ash,
+albumen, and fat, which make up its constituent parts, are shown in separate bottles, the percentage of each
+being stated beneath.</p></div>
+
+<p><span class='pagenum'><a name="Page_49" id="Page_49">49</a></span></p>
+
+<p>Milk varies a good deal in composition; the different
+breeds of cows give varying qualities. The Short-horn
+gives large quantities of milk of rather poor
+analysis, while the Jersey yields smaller proportions
+of very rich milk. During the period of
+lactation (the time which has elapsed since the
+cow gave birth to a calf), care in milking, food,
+health, etc., all have an effect on the quality of
+the milk.</p>
+
+<p>The limits of variation may be stated as
+follows:</p>
+
+<table width="90%" summary="cow's milk" border="0">
+<tr>
+<td class="m60">&nbsp;</td>
+<td class="m17a">Per&nbsp;cent.</td>
+<td class="m5">&nbsp;&nbsp;</td>
+<td class="m17a">Per&nbsp;cent.</td>
+</tr>
+<tr>
+<td class="m60">Water</td>
+<td class="m17a">87.5&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="m5">to</td>
+<td class="m17a">82.5&nbsp;&nbsp;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m60">Fat</td>
+<td class="m17a">2.5&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="m5">"</td>
+<td class="m17a">6.0&nbsp;&nbsp;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m60">Casein and albumen</td>
+<td class="m17a">3.0&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="m5">"</td>
+<td class="m17a">4.5&nbsp;&nbsp;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m60">Milk sugar</td>
+<td class="m17a">3.5&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="m5">"</td>
+<td class="m17a">6.0&nbsp;&nbsp;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m60">Ash</td>
+<td class="m17a">0.6&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="m5">"</td>
+<td class="m17a">0.8&nbsp;&nbsp;&nbsp;&nbsp;</td>
+</tr>
+
+</table>
+
+<p>These figures are extreme, and it is very seldom
+indeed that either the minimum or maximum is
+reached. Indeed, by the regulation laid down under
+Clause 4 of the British Sale of Food and Drugs
+Act of 1899, when the percentage of solids not fat
+falls below 8.5 per cent., and fat under 3 per cent.,
+it is assumed that the milk has been adulterated.
+This regulation is a perfectly just one. While
+genuine milk may, in rare instances, show figures as
+<span class='pagenum'><a name="Page_50" id="Page_50">50</a></span>
+low as 7.1 per cent. of solids not fat, or 2.5 per cent.
+of fat, the right can hardly be claimed of supplying
+such an abnormal article to the public as milk
+of proper quality, and the dairyman who understands
+his business, and wishes to deal fairly with
+his customers, can, by attention to the conditions
+enumerated above which influence the composition
+of milk, entirely avoid the production of such a
+low-grade article.</p>
+
+<p>In the nutrition of both plants and animals
+large quantities of water are needed. The solids
+must be supplied in solution or dissolved in the
+assimilative processes, and this cannot take place
+without water, which also conveys the dissolved
+solids to the various parts of the economy, and in
+the case of animals removes waste materials. For
+the most part, water passes through the body
+unchanged, but a certain proportion unites chemically
+with the food materials and assists in their
+digestion. It is therefore not surprising that
+seven eighths of milk is composed of water. Blood
+contains a similar proportion, and this agreement
+emphasises the fact that milk is a perfectly balanced
+food.</p>
+
+<p>The fat of milk, which yields cream and butter,
+differs in some important respects from other
+<span class='pagenum'><a name="Page_51" id="Page_51">51</a></span>
+fats. Like these, it is made up chiefly of stearin,
+palmitin, and olein, but, in addition, it contains
+an abnormally large proportion of compounds of
+certain of the volatile fatty acids. It is these
+which give to butter its agreeable flavour. By the
+methods of Duclaux, the following is the approximate
+composition of butter fat:</p>
+
+<table width="100%" summary="butter fat" border="0">
+<tr>
+<td class="m80">&nbsp;</td>
+<td class="m20">Per cent.</td>
+</tr>
+<tr>
+<td class="m80"><p class="indent3">Stearin, palmitin, olein, and traces of myristin and butin</p></td>
+<td class="m20">91.50&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Butyrin</td>
+<td class="m20">4.20&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Capronin</td>
+<td class="m20">2.50&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Caprylin, caprinin, and traces of laurin</td>
+<td class="m20">1.80&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">&nbsp;</td>
+<td class="m20">&mdash;&mdash;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">&nbsp;</td>
+<td class="m20">100.00&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">&nbsp;</td>
+<td class="m20">&mdash;&mdash;&mdash;&nbsp;&nbsp;</td>
+</tr>
+
+</table>
+
+<p>Myristin occurs in nutmegs; butyrin in another
+combination flavours pineapples and rum; caprinin
+is found in cocoanut fat, mutton fat, and in the
+offensive odour given off by the goat (from which
+the name is derived); caprylin is a by-product of
+alcoholic fermentation, and also occurs in cocoa
+fat; laurin is found in sweet bay; from which it
+is evident that there are some curious relationships
+in flavouring materials.</p>
+
+<p>Fats are very concentrated foods, furnishing a
+large amount of energy to the body. At one time
+they were classed together with starch, sugar, and
+<span class='pagenum'><a name="Page_52" id="Page_52">52</a></span>
+other carbohydrates as heat-producers, but the
+distinction which was drawn between the kinds
+of food which were thought solely to keep up the
+temperature of the organism, and those which
+produced force in work and other forms of bodily
+energy, has broken down, and by direct experiment
+has been found not to exist. It is usually calculated
+that one part of fat is equal in food value
+to about two and a quarter parts of any of
+the other carbohydrates. Milk fat or butter is
+more digestible than almost any other fat, and its
+importance therefore can readily be realised. All
+the above constituents of milk fat are composed of
+different proportions of carbon, hydrogen, and
+oxygen, but milk also contains minute quantities
+of lecithin, a fat containing phosphorus in addition.
+Lecithin is also found in the brain and nerve
+material of animals, in the yolk of egg, and in
+several plants.</p>
+
+<p>The nitrogenous constituents of milk&mdash;casein
+and albumen&mdash;are usually estimated together,
+and they are reckoned as of equivalent food value.
+The name protein is very commonly applied to
+the total of these bodies in milk, or other animal
+and vegetable foods. They are composed of different
+proportions of carbon, hydrogen, oxygen,
+<span class='pagenum'><a name="Page_53" id="Page_53">53</a></span>
+and nitrogen, with small quantities of sulphur,
+while casein contains phosphorus in addition.
+Albumen exists to the extent of about 0.6 per cent.
+in milk. It is very similar in properties to egg
+albumen. The coagulum which forms on the
+surface of milk when boiled is largely composed of
+albumen. Casein is combined with, and kept in
+solution by, lime, soda, and calcium phosphate, and
+its amount averages a little over 3 per cent.</p>
+
+<p>The remarkable property possessed by rennet,
+of curdling or coagulating casein, is well known;
+rennet is an extract from the stomach of the calf,
+and similar principles are present in the stomachs
+of man and other animals, so that the coagulation
+of milk is the first process in its digestion. If
+milk is gulped down in large quantities it is apt
+to coagulate in lumps, and digestion is much interfered
+with, but if it is taken hot and slowly,
+it coagulates in small pieces which are readily
+attacked by the gastric juice, and milk is then one
+of the most assimilable of foods.</p>
+
+<p>Nature provides that the milk for young animals
+is supplied in finely divided streams, so that coagulation
+takes place in the best possible way.</p>
+
+<p>The proteids are the most important constituents
+of food; they are abundant in the blood,
+<span class='pagenum'><a name="Page_54" id="Page_54">54</a></span>
+and build up the muscles, brain, nerves, and other
+bodily structures.</p>
+
+<p>Besides these mentioned, milk contains traces
+of another proteid of similar composition called
+globulin.</p>
+
+<p>The sugar of milk is not found anywhere else.
+It is a carbohydrate like cane and grape sugar&mdash;that
+is to say, the hydrogen and oxygen they contain
+are in the same relative proportions as in
+water. Milk sugar is not so soluble or so sweet
+as the other sugars. It does not ferment with
+ordinary yeast, but certain special yeasts which
+are made use of in the preparation of keffir,
+koumiss, etc., have the power of transforming it
+into alcohol. Its most remarkable property, however,
+is the facility with which, under the influence
+of certain bacteria, it is changed into lactic acid.</p>
+
+<p>Every one is familiar with the souring of milk,
+but perhaps it is not so generally known that there
+are great differences in the results obtained in
+accordance with the conditions under which the
+souring takes place. The skilled butter-maker,
+by keeping the milk in a cool and cleanly dairy,
+obtains a sour milk of a characteristic and agreeable
+aroma and taste, which beneficially affect the
+flavour of the butter produced. On the other
+<span class='pagenum'><a name="Page_55" id="Page_55">55</a></span>
+hand, if milk is kept in hot and dirty surroundings,
+the development of acidity is accompanied by
+different bad tastes and odours, and it becomes
+unfit for use as a food. In the first case, the
+conditions are favourable to the maximum production
+of the lactic acid bacteria, and these
+occupy the field, and largely prevent the development
+of the other bacteria which are present&mdash;the
+survival of the fittest in the struggle for existence.
+In the second case, the impure surroundings
+swarm with the germs of many kinds of putrefactive
+bacteria, and the high temperature assists
+these to gain the upper hand. Again, the survival
+of the fittest, in the particular conditions. Even
+in cool and cleanly surroundings injurious taints
+may develop, especially if the milk has previously
+been subjected to a journey by road or rail, as is
+the case in the modern creamery system, where
+the farmers deliver their milk to a central creamery,
+where it is made into butter. In such establishments
+it is the regular practice to kill the germs,
+lactic and others, existing in the milk, by heating
+it to a high temperature. This process is called
+pasteurising, after the great French chemist and
+bacteriologist who invented it. Pure lactic cultures
+are added to the pasteurised milk, and the
+<span class='pagenum'><a name="Page_56" id="Page_56">56</a></span>
+souring process is under exact control, with the
+result that butter of uniform flavour and quality
+is produced. The same method is made use of in
+making the special sour milk described in this
+book, with, of course, modifications in the apparatus
+employed, to suit the smaller scale in which
+the manufacture is conducted.</p>
+
+<p>The ash is the mineral matter which is left
+when milk, previously dried, is burnt in a crucible.
+It is a complex mixture, and, as we have seen,
+it amounts to about 0.7 per cent. of the milk.
+The process of burning destroys all the organic
+matter, and, at the same time, alters somewhat
+the state of combination of the inorganic or mineral
+elements. Attempts have been made from the
+analysis of the ash to reconstitute the composition
+of the mineral matter as it exists in the milk.
+The best known is that of Soldner, and the following
+is his calculation:</p>
+
+<table width="90%" summary="butter fat" border="0">
+<tr>
+<td class="m80">&nbsp;</td>
+<td class="m20">Per cent.</td>
+</tr>
+<tr>
+<td class="m80">Sodium chloride</td>
+<td class="m20">10.62&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Potassium chloride</td>
+<td class="m20">9.16&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Monopotassium phosphate</td>
+<td class="m20">12.77&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Dipotassium phosphates</td>
+<td class="m20">9.22&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Potassium citrate</td>
+<td class="m20">5.47&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Dimagnesium citrate</td>
+<td class="m20">3.71&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Magnesium citrate</td>
+<td class="m20">4.05&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Dicalcium phosphate</td>
+<td class="m20">7.42&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80"><span class='pagenum'><a name="Page_57" id="Page_57">57</a></span>Tricalcium phosphates</td>
+<td class="m20">8.90&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Calcium citrate</td>
+<td class="m20">23.55&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80"><p class="indent3">Calcium oxide, in combination with casein</p></td>
+<td class="m20">5.13&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">&nbsp;</td>
+<td class="m20">&mdash;&mdash;&mdash;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">&nbsp;</td>
+<td class="m20">100.00&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">&nbsp;</td>
+<td class="m20">&mdash;&mdash;&mdash;&nbsp;&nbsp;</td>
+</tr>
+
+</table>
+
+<p>The presence of citrates will be noted in this
+analysis. Citric acid, which gives to lemons their
+acidity, and is also found in other fruits, has been
+proved to exist in milk to the extent of about
+0.2 per cent. When alkaline or earthy citrates
+are burnt or oxidised in the blood, the citric acid
+is destroyed, and corresponding carbonates remain.
+No doubt the function of citrates in milk is to
+furnish to the body the earthy and alkaline carbonates
+which are required in certain of its parts.</p>
+
+<p>The mineral constituents of milk have many
+important functions to perform in the building
+up and nutrition of the bodily organism. Phosphate
+of lime is the principal constituent of the
+skeleton, and the blood must be richly supplied
+with the alkalies, earths, and acids which are
+comprehended in the ash.</p>
+
+<p>Milk contains traces of many other substances,
+the most important of which are several enzymes
+which assist in its digestion.</p>
+
+<p><i>General Properties of Milk.</i>&mdash;The appearance
+<span class='pagenum'><a name="Page_58" id="Page_58">58</a></span>
+of milk is known to every one; it ought to be
+a pure white opaque liquid, but very generally
+it is tinted a cream colour with anatto to give it
+an added appearance of richness. The average
+specific gravity is about 1.031; or, to put it another
+way, while a gallon of pure water weighs exactly
+10 lbs., a gallon of milk weighs 10 lbs. 5 oz. It
+freezes at 31&deg; F. and boils at about one third of
+a degree higher than water.</p>
+
+<p>When milk is examined under the microscope,
+the fat is found to be distributed through it in a
+multitude of minute globules varying in size from
+1/16,000th to 1/25,000th part of an inch, and occasionally
+they are much smaller and also much larger.</p>
+
+<p>Fig. 1 is a micro-photograph showing the fat
+globules in whole milk. Fig. 2 is a micro-photograph
+of separated milk, and Fig. 3 a micro-photograph
+of cream, all under high magnification (450
+diams.); from these figures the comparative number
+of fat globules present may be seen.</p>
+
+<table width="100%" summary="fig1 fig2" border="0">
+<tr>
+<td  class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig1" id="fig1"></a><img src="images/fig1.jpg" width="225" height="223" alt=
+"Micro-photograph of a Drop of Whole Milk"
+title="" /></div></td>
+
+<td  class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig2" id="fig2"></a><img src="images/fig2.jpg" width="225" height="230"
+alt="Micro-photograph of Separated Milk" title="" /></div></td>
+</tr>
+<tr>
+<td  class="m50">
+<p><span class="smcap">Fig.</span>&nbsp;1.&mdash;Micro-photograph
+of a Drop of Whole Milk, showing
+distribution of fat globules.
+(Magnified 450 diams.)</p>
+</td>
+
+<td  class="m50">
+<p><span class="smcap">Fig.</span>&nbsp;2.&mdash;Micro-photograph
+of Separated Milk, showing the
+almost complete absence of fat
+globules as compared with
+whole milk. (Magnified 450
+diams.)</p></td>
+</tr>
+</table>
+
+<div class="figcenter" style="width: 225px;"><a name="fig3" id="fig3"></a><img src="images/fig3.jpg" width="225" height="221" alt=
+"Micro-photograph of Cream" title="" />
+
+<p class="cap"><span class="smcap">Fig.</span>&nbsp;3.&mdash;Micro-photograph
+of Cream, showing agglomeration
+of fat globules. (Magnified
+450 diams.)</p></div>
+
+<p>Fats distributed through a watery liquid in this
+finely divided condition form together what is
+called an emulsion, in which the particles of fat
+are kept apart by surface tension. The specific
+gravity of milk fat averages 0.93, and compared
+with water weighing 10 lbs., a gallon of fat would
+<span class='pagenum'><a name="Page_59" id="Page_59">59</a></span>weigh 9 lbs. 5 oz. It is thus considerably lighter
+than the other constituents, and when milk is left
+at rest, the fat globules gradually rise to the top
+and float there, forming cream. The difference in
+specific gravity between cream and milk is taken
+advantage of in the mechanical separator, now so
+much used, and which makes such a thorough
+separation between the two. Cream is an article
+of the most varied composition, according to the
+ideas of the person who produces it, but it ought
+to contain at least 20 per cent. of butter fat, and
+may be made with a much larger percentage if
+necessary. When cream is agitated in a particular
+way, as by churning, the surface tension of the
+particles is overcome, and they run together into
+a mass which forms butter.</p>
+
+<p>The casein of milk is not held in solution in
+the ordinary sense, but in a peculiar state of
+suspension called the colloidal condition, practically
+the whole of it remaining behind when milk
+is filtered through clay filters.</p>
+
+<p>It is this state of suspension of the casein which
+makes milk opaque, but the opacity is considerably
+increased by the emulsified fat.</p>
+
+<p>The coagulation of the casein in milk by the
+addition of rennet has already been referred to.
+<span class='pagenum'><a name="Page_60" id="Page_60">60</a></span>
+Acids, either mineral or organic, also precipitate it
+in the form of flakes. Skimmed milk is now largely
+used for the preparation of casein by this method,
+and the washed and dried precipitate is used very
+extensively in the arts for such varied purposes as the
+manufacture of billiard balls, paints, cements, etc.</p>
+
+<p>The clear liquid which separates when milk is
+curdled with rennet is called whey, and contains
+the milk sugar and mineral salts. The sugar is
+manufactured from it on a limited scale, and is
+used as an ingredient in infant foods, and as a
+convenient medium in certain medical preparations.
+In Sweden a kind of cheese is made from
+whey, but the great bulk of it everywhere is used
+for feeding pigs.</p>
+
+<p>The comparative composition of different varieties
+of milk is given in the following table:<br /><br /></p>
+
+<table width="100%" summary="varieties of milk" border="0">
+<tr>
+<td class="v19c">&nbsp;<br />&nbsp;<br />&nbsp;</td>
+<td class="v9c">&nbsp;<br />Human.<br />&nbsp;</td>
+<td class="v9c">&nbsp;<br />Cow.<br />&nbsp;</td>
+<td class="v9c">&nbsp;<br />Buffalo.<br />&nbsp;</td>
+<td class="v9c">&nbsp;<br />Goat.<br />&nbsp;</td>
+<td class="v9c">&nbsp;<br />Sheep.<br />&nbsp;</td>
+<td class="v9c">&nbsp;<br />Mare.<br />&nbsp;</td>
+<td class="v9c">&nbsp;<br />Ass.<br />&nbsp;</td>
+<td class="v9c">&nbsp;<br />Reindeer.<br />&nbsp;</td>
+<td class="v9c">&nbsp;<br />Whale.<br />&nbsp;</td>
+</tr>
+<tr>
+<td class="v19">&nbsp;<br />Water</td>
+<td class="v9">&nbsp;<br />88.32&nbsp;&nbsp;</td>
+<td class="v9">&nbsp;<br />87.75&nbsp;</td>
+<td class="v9">&nbsp;<br />82.57&nbsp;&nbsp;</td>
+<td class="v9">&nbsp;<br />86.34&nbsp;</td>
+<td class="v9">&nbsp;<br />81.08&nbsp;</td>
+<td class="v9">&nbsp;<br />90.38&nbsp;</td>
+<td class="v9">&nbsp;<br />90.30&nbsp;</td>
+<td class="v9">&nbsp;<br />67.7&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="v9">&nbsp;<br />60.47&nbsp;</td>
+</tr>
+<tr>
+<td class="v19">Fat</td>
+<td class="v9">3.43&nbsp;&nbsp;</td>
+<td class="v9">3.40&nbsp;</td>
+<td class="v9">7.63&nbsp;&nbsp;</td>
+<td class="v9">4.25&nbsp;</td>
+<td class="v9">7.67&nbsp;</td>
+<td class="v9">1.00&nbsp;</td>
+<td class="v9">1.30&nbsp;</td>
+<td class="v9">17.1&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="v9">20.00&nbsp;</td>
+</tr>
+<tr>
+<td class="v19">Protein</td>
+<td class="v9">1.55&nbsp;&nbsp;</td>
+<td class="v9">3.50&nbsp;</td>
+<td class="v9">4.69&nbsp;&nbsp;</td>
+<td class="v9">4.40&nbsp;</td>
+<td class="v9">6.08&nbsp;</td>
+<td class="v9">1.98&nbsp;</td>
+<td class="v9">1.80&nbsp;</td>
+<td class="v9">10.9&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="v9">12.42&nbsp;</td>
+</tr>
+<tr>
+<td class="v19">Milk Sugar</td>
+<td class="v9">6.44&nbsp;&nbsp;</td>
+<td class="v9">4.60&nbsp;</td>
+<td class="v9">4.30&nbsp;&nbsp;</td>
+<td class="v9">4.26&nbsp;</td>
+<td class="v9">4.26&nbsp;</td>
+<td class="v9">6.28&nbsp;</td>
+<td class="v9">6.20&nbsp;</td>
+<td class="v9">2.8&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="v9">5.63&nbsp;</td>
+</tr>
+<tr>
+<td class="v19b">Salts<br />&nbsp;</td>
+<td class="v9b">0.26&nbsp;&nbsp;<br />&nbsp;</td>
+<td class="v9b">0.75&nbsp;<br />&nbsp;</td>
+<td class="v9b">0.81&nbsp;&nbsp;<br />&nbsp;</td>
+<td class="v9b">0.75&nbsp;<br />&nbsp;</td>
+<td class="v9b">0.91&nbsp;<br />&nbsp;</td>
+<td class="v9b">0.36&nbsp;<br />&nbsp;</td>
+<td class="v9b">0.40&nbsp;<br />&nbsp;</td>
+<td class="v9b">1.5&nbsp;&nbsp;&nbsp;&nbsp;<br />&nbsp;</td>
+<td class="v9b">1.48&nbsp;<br />&nbsp;</td>
+</tr>
+<tr>
+<td class="v19ct">&nbsp;<br />Total<br />&nbsp;</td>
+<td class="v9b">&nbsp;<br />100.00&nbsp;&nbsp;</td>
+<td class="v9b">&nbsp;<br />100.00&nbsp;</td>
+<td class="v9b">&nbsp;<br />100.00&nbsp;&nbsp;</td>
+<td class="v9b">&nbsp;<br />100.00&nbsp;</td>
+<td class="v9b">&nbsp;<br />100.00&nbsp;</td>
+<td class="v9b">&nbsp;<br />100.00&nbsp;</td>
+<td class="v9b">&nbsp;<br />100.00&nbsp;</td>
+<td class="v9b">&nbsp;<br />100.0&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="v9b">&nbsp;<br />100.00&nbsp;</td>
+</tr>
+<tr>
+<td class="v19b">&nbsp;<br />Specific Gravity<br />&nbsp;</td>
+<td class="v9b">&nbsp;<br />1.032&nbsp;&nbsp;</td>
+<td class="v9b">&nbsp;<br />1.0315&nbsp;</td>
+<td class="v9b">&nbsp;<br />1.033&nbsp;&nbsp;</td>
+<td class="v9b">&nbsp;<br />1.033&nbsp;</td>
+<td class="v9b">&nbsp;<br />1.038&nbsp;</td>
+<td class="v9b">&nbsp;<br />1.034&nbsp;</td>
+<td class="v9b">&nbsp;<br />1.033&nbsp;</td>
+<td class="v9b">&nbsp;<br />...&nbsp;&nbsp;&nbsp;&nbsp;</td>
+<td class="v9b">&nbsp;<br />...&nbsp;</td>
+</tr>
+</table>
+<p><br /></p>
+
+<table width="90%" summary="Figs. 4a, 4b." border="0">
+<tr>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig4a" id="fig4a"></a><img src="images/fig4a.jpg" width="225" height="223" alt=
+"Photograph of Two Petri Dishes, which have been Inoculated with Ordinary Milk" title="" /></div></td>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><img src="images/fig4b.jpg" width="225" height="217" alt=
+"Milk that has been subjected to sterilisation" title="" /></div></td>
+</tr>
+</table>
+
+<p class="cap"><br /><span class="smcap">Fig.</span> 4 is a photograph of two Petri
+dishes, which have been inoculated with ordinary milk (A), and milk that
+has been subjected to sterilisation (B). The whitish bacterial colonies
+on A are due to enormous numbers of organisms, while B is quite free
+from such growth.<br /><br />
+
+For the production of a reliable lactic food, it is essential that
+certain precautions as to the treatment of the milk, and the maintenance
+of a suitable temperature during the growth of the lactic
+bacteria, should be observed.<br /><br />
+
+In the first place, milk immediately after extraction from the
+cow contains only a few organisms, but these multiply so rapidly
+that in a few hours the bacterial content may amount to many
+millions per ounce. In preparing a pure culture of any specific
+organism, then, care must be taken to destroy all the bacteria that
+have accidentally found their way into the milk, inoculating with
+the organisms it is desired to cultivate. This is best accomplished
+by heating the milk to the boiling-point of water for about thirty
+minutes, by which time almost all the undesirable bacteria have
+been killed.</p>
+
+<p><span class='pagenum'><a name="Page_61" id="Page_61">61</a></span></p>
+
+<p>The milk of the cow differs a good deal from
+human milk, and where the former is used for the
+feeding of children it is usual to add milk sugar
+to it, and otherwise alter it to bring its composition
+more in harmony with the human article. The
+high concentration of the milk of the reindeer and
+the whale is noteworthy. Perhaps this may be
+due to the low temperature conditions in which
+these animals live, necessitating strong nutriment
+to enable their young to make proper progress in
+growth and development. On the other hand,
+the milk of the ass is poor in quality, and probably
+on this account it is more readily assimilated by
+those of weak digestion, to whom it is sometimes
+recommended. Goats' milk is richer than either
+cow or human milk, and its nourishing properties
+are well known. The goat is usually free from
+tuberculosis and other diseases which affect the
+cow, and its milk is therefore a very safe article
+to use.</p>
+
+<p><i>The Analysis of Milk.</i>&mdash;While the analysis of
+milk can only be made by a competent chemist,
+there are a number of simple tests and observations
+by which any intelligent person can obtain
+
+<span class="figleft" style="width: 75px;"><a name="fig5" id="fig5"></a><img src="images/fig5.jpg" width="75" height="195" alt=
+"The Creamometer" title="" />
+<span class="center"><span class="smcap">Fig.</span>&nbsp;5.
+The Creamometer</span></span>
+
+a fair idea of its quality. The taste and smell
+afford some guide, as also the general appearance.
+<span class='pagenum'><a name="Page_62" id="Page_62">62</a></span>
+To judge of the latter, place some of the milk in a
+tumbler or other clear glass vessel. If the milk
+is of good quality it will be quite homogeneous
+and opaque. Any flocculent matter indicates
+either disease in the cow or that the milk is old
+and bacteria have multiplied in it and altered its
+composition. When the milk has stood
+long enough for the cream to rise freely,
+the latter should form a perfectly homogeneous
+and strongly defined layer on the
+top. The quantity of cream may be
+measured in a creamometer, which consists
+of a small glass cylinder graduated
+at the top (Fig. 5). It is filled with
+milk to the top graduation line, and when
+the cream has risen, the percentage quantity of
+the latter which has separated can be taken off.</p>
+
+<p>The colour should be like that of porcelain,
+but, as already stated, it is a common thing for
+the dairyman to add a small quantity of anatto
+or an aniline dye of a similar shade, to give the
+milk a rich creamy tint. If the milk is of a reddish
+colour this may be caused by blood from the udder,
+although certain foods, such as beets, mangels,
+and carrots sometimes give a similar tint. The
+milk given by cows immediately after calving is
+<span class='pagenum'><a name="Page_63" id="Page_63">63</a></span>called "colostrum" or "biestings," and is of a
+yellow or yellow-brown colour. It is much thicker
+than ordinary milk, and coagulates in boiling.</p>
+
+<p>In dirty byres in which care is not taken in
+milking, quite considerable quantities of hairs,
+pieces of manure, and other filth may get into the
+milk. Usually the milk is strained by the dairyman,
+but sometimes this is omitted or carelessly
+done. To test for dirt, a ribbed glass funnel is
+useful. Get a piece of the finest muslin about
+twice the diameter of the funnel, fold over twice,
+so that it becomes one quarter of its original size;
+open one of the sections and place in the funnel;
+pass the milk into this. It will run through
+quickly and some water may be run into the
+funnel to clear away the last traces of milk. The
+filter cloth can then be opened out and any dirt
+retained will become visible. The apparatus is
+shown in Fig. 6.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig6" id="fig6"></a><img src="images/fig6.jpg" width="500" height="685" alt=
+"Testing-Glass for Extraneous Matter in Milk."
+title="" />
+
+<p class="caption"><span class="smcap">Testing-Glass for Extraneous Matter in Milk.</span></p>
+
+<p class="indent2"><span class="smcap">Fig.</span> 6.&mdash;A piece of muslin is folded as shown and a measured quantity of milk
+is passed through the funnel; from the sediment left in the muslin, the
+percentage of extraneous matter may be arrived at.</p></div>
+
+
+<p>If a glass funnel is not available, a very small
+jelly bag can be made of fine gauze and used in
+the same way. The washing water should be
+used in small quantities and directed to concentrating
+the dirt in the apex of the bag. After
+washing, the latter can be turned outside in, to
+permit of readier examination of the dirt. The
+<span class='pagenum'><a name="Page_64" id="Page_64">64</a></span>
+bag should be well washed in cold water, then
+boiled and dried, and is then ready for future
+use.</p>
+
+<p>The acidity of milk is a very useful guide to
+its age. Milk has the curious property of being
+"amphoteric," <i>i.e.</i>, it is both slightly acid and
+slightly alkaline when fresh. As its age increases,
+however, so does its acidity, and at a rate varying
+with the temperature and moisture contents of the
+atmosphere in which it is placed. Old and acid
+milk is heavily contaminated with bacteria, a proportion
+of which are likely to be injurious to health.</p>
+
+<p>The simplest method of testing the acidity is to
+procure a few little books of blue and red litmus
+
+<span class="figleft" style="width: 125px;"><a name="fig7" id="fig7"></a><img src="images/fig7.jpg" width="125" height="233" alt=
+"Lactometer and Test Tube" title="" />
+<span class="center"><span class="smcap">Fig.</span>&nbsp;7. Lactometer
+and Test Tube</span></span>
+
+test papers, and these can be had
+from any philosophical instrument
+maker or laboratory furnisher. The
+strips of test paper are torn out
+and dipped in the milk. When the
+milk is quite fresh it will, owing
+to its amphoteric condition, change
+the red litmus paper slightly blue,
+and the blue litmus paper slightly
+red. Old milk changes blue litmus
+paper to a bright red because of its
+decided acidity.</p>
+
+<p><span class='pagenum'><a name="Page_65" id="Page_65">65</a></span>The above tests do not indicate if the milk is
+poor or rich, but this can be determined by the
+lactometer, an instrument for ascertaining in a
+simple way the specific gravity. The lactometer
+is shown in Fig. 7.</p>
+
+<p>It is graduated usually from 25&deg; to 36&deg;, corresponding
+to specific gravities 1.029 to 1.038. It is
+graduated to degrees and half degrees. Sometimes
+a thermometer is combined with the instrument.
+The specific gravity rises as the temperature is
+lowered and decreases with increase of temperature,
+so that it is important to make the test at the
+figure at which the lactometer was graduated,
+which is usually 60&deg; F. Failing this, an allowance
+has to be made for higher or lower temperatures.
+The milk to be tested is well mixed, and placed
+in a deep vessel, and the lactometer placed in it,
+holding it at first at an angle. It stands upright
+and remains deeper or higher according to the
+specific gravity. The reading is taken on the stem
+at the level of the milk. As the latter is drawn up
+a little round the stem, about a half degree should
+be added on to get the true figure. Thus, if the
+apparent reading is 31, the true reading may be
+taken as 31.5. This is the average figure for good
+milk, corresponding to a specific gravity of 1.0315;
+<span class='pagenum'><a name="Page_66" id="Page_66">66</a></span>
+anything above this is all to the good. Lower
+readings mean inferior quality, the latter being
+proportionate to the lowness of the readings.
+The tests are most conveniently made in a glass
+cylinder (Fig. 7), which may be purchased with
+the lactometer. As there are many inaccurate
+instruments in the market, it is necessary to go to
+a reputable maker, because an unreliable lactometer
+is worse than useless.</p>
+
+<p>The following table gives, in a condensed
+form, the allowances to be made when the temperature
+is above or below the standard (60&deg; F.):</p>
+
+<table width="100%" summary="lactometer" border="0">
+<tr>
+<td class="la16d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+<td class="la7d">&nbsp;</td>
+</tr>
+
+<tr>
+<td class="la16cb">&nbsp;<br />Temperature.<br />&nbsp;</td>
+<td class="la7c" colspan="12">&nbsp;<br />Reading of Lactometer.<br />&nbsp;</td>
+</tr>
+
+<tr>
+<td class="la16ca">Degs. F.</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+<td class="la7">&nbsp;</td>
+</tr>
+<tr>
+<td class="la16">40</td>
+<td class="la7">23.5</td>
+<td class="la7">24.5</td>
+<td class="la7">25.5</td>
+<td class="la7">26.4</td>
+<td class="la7">27.3</td>
+<td class="la7">28.2</td>
+<td class="la7">29.1</td>
+<td class="la7">30.0</td>
+<td class="la7">31.0</td>
+<td class="la7">31.9</td>
+<td class="la7">32.8</td>
+<td class="la7">33.7</td>
+</tr>
+<tr>
+<td class="la16">45</td>
+<td class="la7">23.8</td>
+<td class="la7">24.8</td>
+<td class="la7">25.9</td>
+<td class="la7">26.8</td>
+<td class="la7">27.8</td>
+<td class="la7">28.6</td>
+<td class="la7">29.3</td>
+<td class="la7">30.4</td>
+<td class="la7">31.3</td>
+<td class="la7">32.3</td>
+<td class="la7">33.2</td>
+<td class="la7">34.2</td>
+</tr>
+<tr>
+<td class="la16">50</td>
+<td class="la7">24.1</td>
+<td class="la7">25.1</td>
+<td class="la7">26.1</td>
+<td class="la7">27.0</td>
+<td class="la7">28.0</td>
+<td class="la7">29.0</td>
+<td class="la7">29.9</td>
+<td class="la7">30.9</td>
+<td class="la7">31.8</td>
+<td class="la7">32.8</td>
+<td class="la7">33.7</td>
+<td class="la7">34.7</td>
+</tr>
+<tr>
+<td class="la16">55</td>
+<td class="la7">24.5</td>
+<td class="la7">25.5</td>
+<td class="la7">26.5</td>
+<td class="la7">27.5</td>
+<td class="la7">28.5</td>
+<td class="la7">29.5</td>
+<td class="la7">30.4</td>
+<td class="la7">31.4</td>
+<td class="la7">32.4</td>
+<td class="la7">33.4</td>
+<td class="la7">34.3</td>
+<td class="la7">35.3</td>
+</tr>
+<tr>
+<td class="la16b">60<br />&nbsp;</td>
+<td class="la7b">25.0<br />&nbsp;</td>
+<td class="la7b">26.0<br />&nbsp;</td>
+<td class="la7b">27.0<br />&nbsp;</td>
+<td class="la7b">28.0<br />&nbsp;</td>
+<td class="la7b">29.0<br />&nbsp;</td>
+<td class="la7b">30.0<br />&nbsp;</td>
+<td class="la7b">31.0<br />&nbsp;</td>
+<td class="la7b">32.0<br />&nbsp;</td>
+<td class="la7b">33.0<br />&nbsp;</td>
+<td class="la7b">34.0<br />&nbsp;</td>
+<td class="la7b">35.0<br />&nbsp;</td>
+<td class="la7b">36.0<br />&nbsp;</td>
+</tr>
+<tr>
+<td class="la16">65</td>
+<td class="la7">25.5</td>
+<td class="la7">26.6</td>
+<td class="la7">27.6</td>
+<td class="la7">28.7</td>
+<td class="la7">29.6</td>
+<td class="la7">30.7</td>
+<td class="la7">31.7</td>
+<td class="la7">32.8</td>
+<td class="la7">33.8</td>
+<td class="la7">34.8</td>
+<td class="la7">35.8</td>
+<td class="la7">...&nbsp;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="la16">70</td>
+<td class="la7">26.1</td>
+<td class="la7">27.2</td>
+<td class="la7">28.2</td>
+<td class="la7">29.3</td>
+<td class="la7">30.2</td>
+<td class="la7">31.3</td>
+<td class="la7">32.4</td>
+<td class="la7">33.4</td>
+<td class="la7">34.5</td>
+<td class="la7">35.5</td>
+<td class="la7">36.5</td>
+<td class="la7">...&nbsp;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="la16">75</td>
+<td class="la7">26.8</td>
+<td class="la7">27.8</td>
+<td class="la7">28.8</td>
+<td class="la7">29.9</td>
+<td class="la7">30.8</td>
+<td class="la7">32.1</td>
+<td class="la7">33.1</td>
+<td class="la7">34.2</td>
+<td class="la7">35.2</td>
+<td class="la7">36.3</td>
+<td class="la7">...&nbsp;&nbsp;&nbsp;</td>
+<td class="la7">...&nbsp;&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="la16a">80</td>
+<td class="la7a">27.4</td>
+<td class="la7a">28.4</td>
+<td class="la7a">29.5</td>
+<td class="la7a">30.7</td>
+<td class="la7a">31.6</td>
+<td class="la7a">32.8</td>
+<td class="la7a">33.9</td>
+<td class="la7a">35.9</td>
+<td class="la7a">36.1</td>
+<td class="la7a">...&nbsp;&nbsp;&nbsp;</td>
+<td class="la7a">...&nbsp;&nbsp;&nbsp;</td>
+<td class="la7a">...&nbsp;&nbsp;&nbsp;</td>
+</tr>
+
+</table>
+
+<p>Thus if the thermometer indicates 40&deg; F., and
+the lactometer 29.1&deg;, the true reading at the standard
+temperature of 60&deg; F. is 31&deg;, corresponding
+to a specific gravity of 1.031. Intermediate figures
+<span class='pagenum'><a name="Page_67" id="Page_67">67</a></span>
+can readily be averaged. Care should be taken
+to wash the lactometer with cold water under the
+tap, as otherwise the milk will dry on it and render
+it inaccurate.</p>
+<hr />
+<p><span class='pagenum'><a name="Page_68" id="Page_68">68</a></span></p>
+
+
+
+<h4>CHAPTER IV</h4>
+
+<h5>HANDLING OF MILK</h5>
+
+
+<h6>MODERN DAIRY PRACTICE</h6>
+
+<p>As we have seen, the dairy industry is a very
+ancient one, and has been intimately associated
+with the development of civilisation.</p>
+
+<p>Within historical times dairying has always
+formed a prominent feature in connection with
+agriculture, and the use of milk in one form or
+another has been common to every civilised
+nation.<a name="FNanchor_42" id="FNanchor_42"></a><a href="#Footnote_42" class="fnanchor">42</a></p>
+
+<p>The greatest progress, however, in the study
+of milk has taken place since about the year 1890,
+at which time the dairy industry seems to have
+attracted the general attention of food specialists
+and scientific investigators throughout the world.
+Since then it has been considered worth while
+to enact laws in different countries with regard
+to the regulation and control of the milk supply.</p>
+
+<p>Since 1903 there has been an International
+<span class='pagenum'><a name="Page_69" id="Page_69">69</a></span>Dairy Federation formed, and it has held conferences
+at Brussels, Paris, The Hague, and Buda-Pest,
+and in 1911 it will hold a conference in
+Stockholm. The Federation was started in a
+very humble way in Brussels, and owes its origin,
+to a large extent, to a distinguished Belgian agriculturist,
+Baron Peers of Oostcamp, Bruges; but
+at the present day a general committee composed
+of representatives of nearly every civilised nation
+has been formed, and delegates from such countries
+attend the Congresses, which are held every
+two years. The literature which has arisen out
+of these International Congresses has been disseminated
+in different countries, and has been
+instrumental in placing the dairy industry on a
+thoroughly scientific basis.</p>
+
+
+<p><i>Milk Supply of the United Kingdom.</i>&mdash;The
+milk supply of the United Kingdom has steadily
+grown from year to year, and in relation to the
+population works out at fifteen gallons per head.
+The manner in which these figures are arrived at
+is shown in the following estimate:</p>
+
+<div class="blockquot"><p>The population of the United Kingdom is now about
+45,500,000. The number of cows or heifers in calf or in
+milk in June, 1909, was 3,360,600; the number in 1910
+was probably about 4,400,000.<br /><br />
+
+<span class='pagenum'><a name="Page_70" id="Page_70">70</a></span>
+Of these about 300,000 were heifers that had not yet
+produced any milk. The actual milking class, therefore,
+comprised about 4,100,000 cows and heifers; of these,
+about 600,000 were heifers that calved in the winter
+and spring of 1909-10, and 300,000 were heifers that calved
+in the summer and autumn of 1910. The number of cows
+that produced two or more calves may be taken to be about
+3,200,000; of these about 600,000 should have produced
+their second calf in the winter and spring 1909-10, and
+would be milked as heifers in the summer and autumn of
+1910; the number of mature cows from which a full season's
+supply of milk was obtained during the twelve months
+from June 5, 1909, to June 4, 1910, was apparently about
+2,600,000. A large quantity of milk is yielded during the
+year by cows sold or lost during the twelve months before
+the census. Possibly ten per cent. of the milk produced
+in the twelve months from June, 1909, to June, 1910, was
+yielded by cows that were sold or lost before the census
+of June, 1910.<br /><br />
+
+It is estimated that the 3,200,000 cows (including the
+600,000 that up to the winter of 1909-10 were heifers)
+produced, on the average, 44 cwts. (480 gallons) of milk
+per head in the twelve months from June 5, 1909, to June
+4, 1910; the 300,000 heifers that calved in the summer and
+autumn, 30 cwts. (330 gallons) per head; the 600,000
+heifers that calved in the winter and spring of 1909-10,
+15 cwts. (165 gallons), making the total quantity of milk
+produced in the twelve months by cows and heifers on
+the farms, and that produced calves during the twelve
+months (June, 1909-1910), 158,800,000 cwts. (1,746,800,000
+gallons), or about 426 gallons per head, and about 400
+gallons per head for all the cows and heifers in milk or in
+calf in 1910. There remains to add the milk yielded by the
+cows that were sold during the twelve months, and of cows
+<span class='pagenum'><a name="Page_71" id="Page_71">71</a></span>
+and heifers in feeding pastures that were milked during
+the twelve months, June to June, 1909-10, and which
+probably formed one tenth of the whole supply, making
+the total supply for the twelve months 176,444,000 cwts.,
+or 1,940,884,000 gallons. This equals 2 tons, or 440 gallons
+per head, crediting the whole supply to the 4,400,000
+cows and heifers in milk or in calf in June, 1910. At 7-1/4d.
+per gallon the value of milk produced in the United Kingdom
+in the twelve months was &pound;58,600,000. Including
+the value at birth of the calves, the total value of the produce
+of the milk-giving class would be about &pound;62,000,000.
+The value of the milk, butter, cheese, and cream sold
+or consumed in farmhouses would be about &pound;48,000,000,
+or equal to about 24 per cent. of the gross annual income
+of farmers.<br /><br />
+
+The average consumption of new milk is about 15 gallons
+per head of the population. During the twelve months
+of 1911, the quantity required for this purpose will be about
+682,500,000 gallons, or about 35 per cent. of the total
+supply; calves will require about 10 per cent. of the supply;
+the quantity available for butter and cheese will equal
+about 55 per cent. of the supply.
+<a name="FNanchor_43" id="FNanchor_43"></a>
+<a href="#Footnote_43" class="fnanchor">43</a></p></div>
+
+<p><i>The Milk Industry in the United States.</i>&mdash;In the
+United States of America, where the habits of
+the people are somewhat analogous to those in
+the United Kingdom, it is estimated that the
+milk from five million cows is annually consumed,
+which averages twenty-five and one half gallons
+<span class='pagenum'><a name="Page_72" id="Page_72">72</a></span>per year for each person, or equal to an ordinary
+sized tumblerful each day.<a name="FNanchor_44" id="FNanchor_44"></a><a href="#Footnote_44" class="fnanchor">44</a></p>
+
+
+<p>Such a vast industry, so intimately associated
+with the food of the bulk of the people, naturally
+invites the closest study, and, as a consequence,
+the literature on the subject, which has arisen
+during the last twenty years, has been of a voluminous
+character, not only from the point of view
+of practice, but from that of bacteriology, chemistry,
+and hygiene.</p>
+
+<p>A pure milk supply is essential to health, and
+it seems unfortunate that the ordinary milk producer
+should, in a great many cases, take up an
+antagonistic attitude to the scientific methods of
+handling milk. There is a body of opinion being
+created, however, which is likely to alter this
+attitude in the next generation, and this is attributable
+to the fact that so much excellent work
+has been done at numerous dairy colleges and
+institutes in all civilised countries that the dairy
+industry is emerging from a period of rule-of-thumb
+procedure to its proper place as one of the
+technical arts.</p>
+
+<p><i>Transmission of Disease in Milk.</i>&mdash;It is not to
+be wondered at that the handling of milk should
+<span class='pagenum'><a name="Page_73" id="Page_73">73</a></span>now be regarded as a technical business, seeing
+that milk-borne disease is one of the commonest
+with which we have to deal.</p>
+
+<p>The commoner diseases which have been transmitted
+by milk are scarlet fever, typhoid, diphtheria,
+tuberculosis, sore throat epidemics. Others
+of a more complex character have been traced to
+the same source of infection, and the clearest
+possible evidence has been furnished of the transmission
+of diseases by means of micro-organisms,
+which have contaminated the milk supply.</p>
+
+<p>It is therefore necessary to watch over the milk
+from the source of supply to its consumption.
+It is primarily on the farm and in the cow-house
+that methods of handling in a hygienic way should
+be insisted on, as microbial contamination increases
+at a prodigious rate, and it is the early
+microbe therefore which does the most damage.</p>
+
+<p>The milk in the udder, for all practical purposes,
+may be assumed to be sterile, and the contamination
+which takes place originates, therefore,
+from external sources.</p>
+
+<p>One of the principal means of infection is from
+hairs which fall from the cow into the milk, and
+many of which are carriers of dangerous micro-organisms.</p>
+
+<p><span class='pagenum'><a name="Page_74" id="Page_74">74</a></span>
+There is also a certain amount of offensive
+dirty matter which may fall into the milk-pail,
+and carry with it undesirable germs.</p>
+
+<p>These impurities may, to a certain extent, be
+eliminated by good straining, but a surer prevention
+is to have the cow-house perfectly clean
+and free from dust, as dust specks are in many
+cases the vehicles of disease germs. Cleanliness
+is, in fact, the essential feature in modern dairying,
+not only in the cow-house, but in the milking
+utensils, the drainage, etc., and, above all, the
+milker should be of cleanly habits.</p>
+
+<p>The flavours of milk sometimes arise from the
+absorption of evil-smelling gases in the cow-house,
+or from a peculiar taint from certain roots
+and feeding stuffs, and in such a case it is desirable
+that a&euml;ration should take place in a fresh clear
+atmosphere, so that oxygenation may have the
+effect of eliminating and destroying the foreign
+odours and flavours which may be present. If
+this process of a&euml;ration is carried out at blood
+heat, the result is generally highly satisfactory.</p>
+
+<p><i>Milk Management.</i>&mdash;There have been many
+excellent tables of rules published for the management
+of dairies in different countries, but they are
+necessarily framed within certain limitations which
+<span class='pagenum'><a name="Page_75" id="Page_75">75</a></span>
+apply to all. The following is an excellent set,
+which put concisely the conditions necessary to
+be observed in the modern cow-house:</p>
+
+<div class="blockquot3"><p class="indent4">1. The cow should be sound&mdash;no disease should exist in the
+animal.</p>
+
+<p class="indent4">2. The feed should be good and free from aromatic substances.
+If these aromatic foods are used, they should be employed
+according to those methods which will not cause odours or
+flavours to appear in the milk.</p>
+
+<p class="indent4">3. The cow should be groomed, and hair about the udder preferably
+clipped.</p>
+
+<p class="indent4">4. The udder should be moistened during milking.</p>
+
+<p class="indent4">5. The milker should be a neat, tidy person.</p>
+
+<p class="indent4">6. The milker should be free from disease, and should not come
+in contact with any communicable disease.</p>
+
+<p class="indent4">7. The milker's clothes and hands should be clean while milking.</p>
+
+<p class="indent4">8. The pail should be sterilised.</p>
+
+<p class="indent4">9. The stall should be such as to reduce the amount of disturbance
+of dust and dirt.</p>
+
+<p class="indent4">10. There should be good light, good ventilation, and good
+drainage in the cow-house.</p>
+
+<p class="indent4">11. The cow-house should always be kept clean.</p>
+
+<p class="indent4">12. Feeding and bedding, unless moist, should be done after
+milking.</p>
+
+<p class="indent4">13. A dustless milking-room is desirable.</p>
+
+<p class="indent4">14. Milk should not stand in the cow-house.</p>
+
+<p class="indent4">15. If milk is a&euml;rated, it should be done before cooling and in
+pure air.</p>
+
+<p class="indent4">16. The sooner the milk is cooled after milking the better.</p>
+
+<p class="indent4">17. Keep the milk as cold as possible when once cooled.<a name="FNanchor_45" id="FNanchor_45"></a><a href="#Footnote_45" class="fnanchor">45</a></p></div>
+
+<p>The supply of milk is conducted, to a large
+extent, by towns' dairies, which depend for their
+supplies upon the dairy farm in the country, and
+<span class='pagenum'><a name="Page_76" id="Page_76">76</a></span>it is obvious that a certain period of time must
+elapse, in the generality of cases, before a town's
+dairy receives its supply in the ordinary course,
+and this constitutes the greatest difficulty in
+modern dairy practice, owing to the liability of
+the milk to absorb bacteria, which during transit
+may multiply enormously.</p>
+
+<p>The multiplying of bacteria in milk at different
+temperatures is easily demonstrated, and the
+result of this has been stated in various forms
+many times over. As a graphic means, however,
+of showing the increase that takes place in the
+numbers of germs present, and the consequent
+product of acidity, the table below by Conn may
+be given.</p>
+
+<p>The consequent result of the increase in bacteria
+is the production of lactic acid, which produces
+the souring so familiar in milk which has been
+kept in the household at a high temperature.</p>
+
+<div class="center">
+<i>Numbers of Bacteria per c.cm. in Milk kept at
+Different Temperatures.</i></div>
+
+
+<table width="100%" summary="Bacteria" border="0">
+<tr>
+<td class="ba12c">Number<br />at<br />Outset</td>
+<td class="ba12">In 12<br />hrs.at<br />50&deg; F.</td>
+<td class="ba12">In 12<br />hrs.at<br />70&deg; F.</td>
+<td class="ba12">In 50hrs.<br />at 50&deg; F.</td>
+<td class="ba28">In 50 hrs. or at time<br />of curdling at 70&deg; F.</td>
+<td class="ba12">No. hrs.<br />to curdle<br />at 50&deg; F.</td>
+<td class="ba12">No. hrs.<br />to curdle<br />at 70&deg; F.</td>
+</tr>
+<tr>
+<td class="ba12d">&nbsp;<br />46,000</td>
+<td class="ba12a">&nbsp;<br />39,000</td>
+<td class="ba12a">&nbsp;<br />249,500</td>
+<td class="ba12a">&nbsp;<br />1,500,000</td>
+<td class="ba28a">&nbsp;<br />542,000,000</td>
+<td class="ba12a">&nbsp;<br />190</td>
+<td class="ba12a">&nbsp;<br />56</td>
+</tr>
+<tr>
+<td class="ba12d">47,000</td>
+<td class="ba12a">44,800</td>
+<td class="ba12a">360,000</td>
+<td class="ba12a">127,500</td>
+<td class="ba28a">792,000,000.36 hrs.</td>
+<td class="ba12a">289</td>
+<td class="ba12a">36</td>
+</tr>
+<tr>
+<td class="ba12e">50,000<br />&nbsp;</td>
+<td class="ba12b">35,000<br />&nbsp;</td>
+<td class="ba12b">800,000<br />&nbsp;</td>
+<td class="ba12b">160,000<br />&nbsp;</td>
+<td class="ba28b">2,560,000,000.42 hrs.<br />&nbsp;</td>
+<td class="ba12b">172<br />&nbsp;</td>
+<td class="ba12b">42<br />&nbsp;</td>
+</tr>
+
+</table>
+<p><span class='pagenum'><a name="Page_77" id="Page_77">77</a></span></p>
+
+<p>What actually happens is that the lactic acid is
+produced by the breaking up of the milk sugar, and
+the appearance of this sourness is an indication that
+a period has been reached in the age of the milk
+which may be described as being&mdash;unwholesome.<a name="FNanchor_46" id="FNanchor_46"></a><a href="#Footnote_46" class="fnanchor">46</a></p>
+
+<p>It is necessary, therefore, for the town's milk
+dairy to be equipped in such a way as to deal
+promptly with the milk supply.</p>
+
+<p>We have seen that the milk should first of all
+be a&euml;rated at blood heat, so as to liberate objectionable
+odours, after which it should be cooled to
+as low a temperature as possible, by means of
+well water. When these operations have been
+performed on the farm, milk should be sent as
+rapidly as possible to the distributing towns'
+dairies, and should be transported in refrigerated
+waggons, cooled preferably with ice, during the
+journey. On arrival at the town dairy, it will
+be necessary to pasteurise the milk&mdash;that is to
+say, the milk should be heated to such a temperature
+as will destroy any pathogenic organisms
+which may be present, and the pasteurising temperature
+should therefore be in excess of the
+thermal death-point of all such organisms.</p>
+
+<p><span class='pagenum'><a name="Page_78" id="Page_78">78</a></span>
+Pasteurisation owes its origin to Pasteur, and
+has become an adopted method throughout the
+dairy industry, and there are many mechanical
+devices termed "pasteurisers" (see Fig. 8) which
+are used for the carrying out of this particular
+operation. The form of one of these is that of a
+vertical jacketed cylinder with paraboloidal surface,
+around which steam is made to pass, so as to
+maintain the temperature at about 176&deg; F. Milk
+is allowed to flow in at the bottom of the paraboloidal
+surface, and is caught by mechanical
+agitating arms, which revolve at a given speed,
+and by this action milk is distributed centrifugally
+over the paraboloidal surface, and is forced
+out by the same action, at the top of the apparatus,
+after being heated.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig8" id="fig8"></a><img src="images/fig8.jpg" width="500" height="768" alt=
+"Pasteuriser" title="" />
+
+<p class="caption"><span class="smcap">Pasteuriser</span></p>
+
+<p class="indent2"><span class="smcap">Fig.</span> 8.&mdash;The milk enters from the bottom and circulates
+to the top of the inside cylinder, which is paraboloidal
+in construction. It is heated as it passes
+through the apparatus, and is discharged at the top
+at a temperature of 176&deg; F.</p></div>
+
+
+<p>The centrifugal action is sufficient to raise the
+milk some three to four feet, through a tube, and
+this is taken advantage of so as to cause the milk
+to flow over a conical cooler, described as a primary
+cooler, and in which water is made to circulate.
+As the hot milk descends over the conical cooler
+it gives up most of its acquired heat to the water,
+and, in practice, is reduced in temperature to within
+4&deg; of the temperature of the water.</p>
+
+
+<p>Below this primary cooler is fixed a cooler of
+<span class='pagenum'><a name="Page_79" id="Page_79">79</a></span>the same size and shape, which is termed a secondary
+cooler. In it, brine at a temperature of about
+35&deg; F. is circulated from a refrigerating machine,
+and, as the milk falls over the secondary cooler,
+it is cooled to a temperature of about 40&deg; F.,
+when it may be looked upon as being pasteurised
+and free from all pathogenic organisms, in which
+state it will keep for a considerable length of
+time.</p>
+
+<p>It is desirable that the milk should, as soon
+as possible after the cooling takes place, be delivered
+to the consumers, and be kept under cool
+conditions, either in bottles or in a closed vessel
+covered over with muslin, so as to keep out specks
+of germ-laden dust.</p>
+
+<p>Briefly speaking, the foregoing is an outline of
+what is carried on in the ordinary dairy practice.</p>
+
+<p>There are many modifications of this practice,
+such as the introduction of regenerative heaters,
+so as to utilise a portion of the heat of pasteurisation,
+which would otherwise be wasted.</p>
+
+<p>In some cases, again, it is considered necessary
+to conduct the primary and secondary cooling
+over coolers furnished with mantles, so that the
+atmospheric bacteria which are everywhere present
+should be shut off from the falling milk.</p>
+
+<p><span class='pagenum'><a name="Page_80" id="Page_80">80</a></span>
+Ordinarily, however, the equipment for a town's
+dairy consists of:</p>
+
+<p>1. Steam-boiler to generate steam for pasteurising,
+scalding, etc.</p>
+
+<p>2. Motive power, which may be either a steam-engine,
+gas-engine, or electric motor.</p>
+
+<p>3. Refrigerating machine, which is used for
+supplying cold brine to the secondary cooler.
+In many cases it is also used for cooling a room in
+which the milk and cream are stored.</p>
+
+<p>4. Milk-receiving tank.</p>
+
+<p>5. Milk-strainer.</p>
+
+<p>6. Pasteurising apparatus, and primary and
+secondary coolers.</p>
+
+<p>Such a plant is necessary in order to conduct
+an ordinary town dairy business in anything
+like a hygienic way, and is designed only
+for the handling of milk intended for domestic
+consumption.</p>
+
+<p>There are times when another plant might be
+necessary, such as a plant for the separation of
+milk, or for utilising it for the production of
+butter or cheese, such operations being subject
+to the fluctuations in the milk supply.</p>
+
+<p>It is sometimes desirable also to use up an
+excess of milk for cheese or butter-making; hence
+<span class='pagenum'><a name="Page_81" id="Page_81">81</a></span>
+it is necessary to provide such apparatus as has
+been indicated.</p>
+
+<p><i>Preparation of Soured Milk.</i>&mdash;The foregoing
+description has been given in some detail, as
+showing the ordinary practice, and we now come
+to consider how it can be modified so as to provide
+for the production of soured milk. It may first
+of all be premised that within the next few years
+the preparation of soured milk as an ordinary
+production of the dairy will be universal, and will
+form a part of the ordinary dairy practice. The
+apparatus, therefore, which is necessary is one
+of considerable interest to all who are engaged in
+the dairy industry.</p>
+
+<p>As will be seen from the chapter describing
+the preparation of soured milk in the dairy, this
+process can be conveniently carried on, so as to
+utilise the plant which is at present in general
+use. The milk can be received in the same way,
+pasteurised and cooled to about blood-heat, after
+which its preparation as soured milk is a very
+simple matter, and only requires a certain amount
+of careful attention.</p>
+
+<p>For the keeping of soured milk, a cold room
+cooled by a refrigerating machine would be desirable,
+so as to maintain the fermented milk at a
+<span class='pagenum'><a name="Page_82" id="Page_82">82</a></span>
+low temperature and prevent over-fermentation.</p>
+
+<p>Apparatus has been designed so as to handle
+soured milk on a large scale, and one of the machines
+is shown on the illustration (see Fig. 9).
+It is simply a jacketed cylinder with a cover and
+an agitating gear. The inside of the machine is
+nickel-plated, and there is an arrangement whereby
+the cooling may be done rapidly, through a coil
+inside the jacket, this coil being connected to the
+brine circulation of the refrigerating machine.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig9" id="fig9"></a><img src="images/fig9.jpg" width="500" height="507" alt=
+"Continuous Apparatus for the Production of Large
+Quantities of Soured Milk"
+title="" />
+
+<p class="caption"><span class="smcap">Continuous Apparatus for the Production of Large
+Quantities of Soured Milk</span></p>
+
+<p class="indent2"><span class="smcap">Fig.</span> 9&mdash;This apparatus is made by the Dairy Machinery and Construction
+Company of Shelton, Conn., U S A. The milk is agitated
+inside a jacketed cylinder, where it is allowed to incubate at about
+blood heat. The milk can be rapidly heated and also rapidly
+cooled by means of this apparatus.</p></div>
+
+<p>The machine is filled with milk containing three
+per cent. of fat, which has been previously pasteurised
+to about 190&deg; F., and cooled down to about
+90&deg; F.; at this point the pure culture of <i>Bacillus
+bulgaricus</i> is introduced, and the agitator is kept
+working, so as to mingle it thoroughly with the
+milk. The agitator is then stopped until the
+acidity shows a test of 0.9 to 1.0 per cent., when
+the agitator is again started, and cold brine from
+the refrigerating machine is turned on to the cooling
+pipes, so that the product is thoroughly broken
+up, and cooled down to 40&deg; F.</p>
+
+<p>The milk is then transferred to a bottle-filling
+machine (Fig. 10), poured into bottles and hermetically
+sealed, after which it is ready for consumption.
+When it has to be kept for any time it
+<span class='pagenum'><a name="Page_83" id="Page_83">83</a></span>should be placed in a cold room where there is a
+temperature not higher than 40&deg; F.</p>
+
+
+<p>The process, therefore, is a simple one, and lends
+itself to the ordinary dairy business, without involving
+any great expenditure on account of a
+new plant.</p>
+
+<hr />
+<p><span class='pagenum'><a name="Page_84" id="Page_84">84</a></span></p>
+<h4>CHAPTER V</h4>
+
+<h5>THE BACTERIOLOGY OF FERMENTED OR SOURED
+MILK</h5>
+
+<h6>A CHAPTER FOR STUDENTS</h6>
+
+<p>During the last few years much work has been
+done in investigating the action of various classes
+of organisms&mdash;bacteria, yeasts, and moulds&mdash;upon
+milk and its products. While, however, the attention
+of the dairyman has been chiefly directed
+to the propagation of acid-producing organisms
+and the use of pure cultures of lactic acid bacteria
+in their relation to butter and cheese making, a
+new sphere in micro-biology has been disclosed
+by the study of the effects caused by the combined
+growth of two or more different classes of organisms
+in milk and the consequent production of
+lactic, alcoholic, and gaseous fermentations. The
+simultaneous occurrence of these fermentative
+changes is responsible for the formation of such
+<span class='pagenum'><a name="Page_85" id="Page_85">85</a></span>
+beverages as keffir, koumiss, milk-wine, etc. It
+has therefore become essential, in connection with
+the study of new developments in the milk
+industry, that we should make a more intimate
+acquaintance with the bacteriology of the ferments
+involved.</p>
+
+<p><i>Keffir</i> (<i>kephir</i>, <i>kifyr</i>, <i>kiafyr</i>, <i>kephor</i>, <i>kyppe</i>) is
+the name given to an acid, slightly alcoholic
+drink, which for many centuries has been prepared
+by the nomadic tribes in the Caucasus.
+The characteristic fermentation is induced by
+the addition of so-called keffir grains. These are
+yellow or golden-yellow, warty, and furrowed
+flakes or nodules, the former varying in size from
+that of a rice grain to that of a bean, while the
+latter are often about an inch across and one
+eighth of an inch thick. Bearing in mind the fact
+that the preparation of keffir has been carried on
+for many centuries, it is not surprising that the
+origin of these grains should be surrounded by
+myths.</p>
+
+<p>The belief is prevalent among the Mohammedan
+tribes of the Caucasus that keffir grains were, in
+the first instance, presented by Allah, as a sign
+of immortality, to one preferred tribe. Others
+hold that, in past ages, they were found by shepherds
+<span class='pagenum'><a name="Page_86" id="Page_86">86</a></span>
+growing on a shrub in the Caucasian highlands;
+while, according to Skolotowski,<a name="FNanchor_47" id="FNanchor_47"></a><a href="#Footnote_47" class="fnanchor">47</a> they were
+originally found adhering to the walls of an oaken
+vessel used for the preparation of airam. This is
+a soured milk beverage similar to keffir, but possessing
+a weaker alcoholic fermentation, and prepared
+from goats' milk by the addition of pieces of
+calf's stomach. This would undoubtedly serve
+to introduce various species of lactic acid bacteria,
+and will be referred to in the portion dealing with
+soured milks. Keffir is prepared by the Caucasians
+from cows', sheep's, or goats' milk, and the operation
+is carried on in large leathern tubes or bottles.
+After the addition of the grains or seeds to the
+milk the vessel is placed in a cool chamber, and the
+fermentation is allowed to proceed for one or two
+days, by the end of which time the normal fermentation
+is at an end. During this period the
+keffir grains have increased enormously in size,
+assume a bright yellow colour, and lose their
+sour buttery smell.</p>
+
+<p>Previous to the removal of the fermented
+liquid, a portion of the bottle is firmly bound from
+the rest by a stout cord, and the greater portion
+of the remaining keffir is quickly removed for use,
+<span class='pagenum'><a name="Page_87" id="Page_87">87</a></span>
+thus avoiding, as far as practicable, any outside
+infection. After the addition of fresh warm milk
+the cord round the end of the bottle is removed,
+and the old and new milk thoroughly mixed for a
+time in order to ensure uniform inoculation of the
+new milk for the next fermentation. During the
+winter months the leathern vessels are often placed
+in the sunshine, so that the temperature remains
+at 61&deg; to 65&deg; F.</p>
+
+
+<p>The necessary agitation of the vessel is said to
+be supplied in the form of kicks by passers-by
+or by the children during their play.</p>
+
+<p>The beverage prepared in this way is so gaseous
+in character that it is often blown forcibly from
+the vessel during removal, and possesses, according
+to Podowyssozki,<a name="FNanchor_48" id="FNanchor_48"></a><a href="#Footnote_48" class="fnanchor">48</a> a very acid taste.</p>
+
+<p>During any interruption in the preparation of
+keffir in the above manner, the grains are taken out,
+and after having been well washed in clean water, are
+spread out on a clean cloth to dry in the sunshine.
+They thereby assume a characteristic cheesy or
+buttery odour and become rather darker in colour.
+Thorough desiccation is essential in order to prevent
+subsequent mouldiness or disease of the grain.</p>
+
+<p><span class='pagenum'><a name="Page_88" id="Page_88">88</a></span>
+In European countries the grains are subjected
+to a preliminary soaking in water for five to six
+hours and then placed in four to five changes of
+milk, each change having a duration of two to
+three hours. As soon as the grains commence
+to rise to the surface of the milk, they may be
+used for the actual preparation. To this end,
+a small quantity of the grain is added to freshly
+boiled milk and allowed to stand for eight to
+twelve hours at a temperature of 55&deg;-62&deg; F.
+with agitation of the flask every two hours. By
+this time the milk, now known as Sakwaska, has
+become abundantly inoculated with the organisms
+essential to the fermentation, and after the removal
+of the grains, may be poured into well-corked flasks
+for the secondary brew. The flasks should be
+kept at a lower temperature for twenty-four to
+forty-eight hours, by which time the product
+is ready for consumption.</p>
+
+<p>According to the temperature and length of
+period to which this subsequent fermentation
+is allowed to proceed, the resultant keffir is more
+or less acid and gaseous. The grains may again
+be used for starting a fresh portion of milk, and
+a regular supply obtained in this manner. Well-fermented
+forty-eight-hours-old keffir should be
+<span class='pagenum'><a name="Page_89" id="Page_89">89</a></span>
+an effervescent beverage with prickling and acid
+taste and a consistency and smell similar to sour
+cream. Large, persistent bubbles should form
+on the surface of the liquid and the casein be
+present as an extremely fine flocculent precipitate
+which remains suspended for a considerable
+time.</p>
+
+<p>From the third day there ensues a gradual
+peptonisation of the casein. If the temperature
+at which the secondary fermentation has occurred
+should be higher than 72&deg; F., or if the milk has
+not been sufficiently agitated, then the casein will
+be present in the form of porous small flakes,
+which on shaking form a fine emulsion.</p>
+
+<p>The chemical changes undergone by the milk
+during the preparation of keffir are confined almost
+exclusively to the milk sugar. As already stated,
+a slight peptonisation occurs in old samples, but
+this depends very largely upon the method of
+preparation and purity of the culture. Hammersten<a name="FNanchor_49" id="FNanchor_49"></a><a href="#Footnote_49" class="fnanchor">49</a>
+and Essaulow<a name="FNanchor_50" id="FNanchor_50"></a><a href="#Footnote_50" class="fnanchor">50</a> show, however, that this
+is not a concomitant of normal fermentation.
+According to Hammersten, normal keffir contains&mdash;</p>
+
+<p><span class='pagenum'><a name="Page_90" id="Page_90">90</a></span></p>
+
+<table width="67%" summary="butter fat" border="0">
+<tr>
+<td class="m80">&nbsp;</td>
+<td class="m20">Per&nbsp;cent.</td>
+</tr>
+<tr>
+<td class="m80">Water</td>
+<td class="m20">88.26&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Fat</td>
+<td class="m20">3.35&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Casein</td>
+<td class="m20">2.98&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Lactalbumen</td>
+<td class="m20">0.28&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Peptones</td>
+<td class="m20">0.05&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Milk sugar</td>
+<td class="m20">2.78&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Lactic acid</td>
+<td class="m20">0.81&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Alcohol</td>
+<td class="m20">0.70&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="m80">Ash</td>
+<td class="m20">0.79&nbsp;&nbsp;</td>
+</tr>
+
+</table>
+
+<p>In no case should the acid be higher than 1.0
+per cent., and the alcohol more than 0.75 per cent.</p>
+
+<p><i>Biology of the Keffir Grain.</i>&mdash;The first communication
+on the biology of the keffir grain seems
+to have been made by Kern.<a name="FNanchor_51" id="FNanchor_51"></a><a href="#Footnote_51" class="fnanchor">51</a> He regarded
+the grain as a zo&ouml;gl&oelig;a composed of bacilli and
+yeasts, the latter being regarded as the ordinary
+beer yeast (<i>Saccharomyces cerevisse&aelig;</i>), while to
+the former he gave the name of <i>Dispora caucasica</i>.
+As the name indicates, this bacillus possesses two
+polar spores, and germination of these proceeded
+in the same manner as with <i>Bac. subtilis</i>. As,
+however, pure cultures of the organisms were not
+made, and the descriptions and illustrations made
+by Kern fail to show any distinctive characteristics,
+it seems probable that accidental confusion with
+other organisms must have occurred.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig10" id="fig10"></a><img src="images/fig10.jpg" width="500" height="521"
+alt="A Milk Filling Apparatus" title="" />
+
+<p class="caption"><span class="smcap">A Milk Filling Apparatus</span></p>
+
+<p class="indent2"><span class="smcap">Fig.</span> 10&mdash;Where soured milk is handled on the large scale,
+a special filling apparatus for bottles is desirable, and
+the soured milk supply should be under cover as shown.
+This apparatus is made by the Dairy Machinery and
+Construction Company.</p></div>
+
+<p><span class='pagenum'><a name="Page_91" id="Page_91">91</a></span>Krannhals<a name="FNanchor_52" id="FNanchor_52"></a><a href="#Footnote_52" class="fnanchor">52</a> succeeded in isolating ten different
+keffir bacteria among which were several sporulating
+bacteria. Here too it is impossible to attach
+any importance to the results, as the artificial
+preparation of keffir, by means of these bacteria,
+was not attempted. Beijerinck<a name="FNanchor_53" id="FNanchor_53"></a><a href="#Footnote_53" class="fnanchor">53</a> studied the organisms
+constituting keffir grains and attached
+prime importance to the occurrence of two organisms,
+viz., (<i>a</i>) a yeast, <i>Saccharomyces kefir</i>, which
+was capable of inverting milk sugar by means of
+an enzyme (lactase) and afterwards fermented
+the products with the formation of alcohol and
+carbon dioxide, and also (<i>b</i>) a non-motile non-sporulating
+bacterium, afterwards <i>Lactobac. caucasicus</i>.
+The latter, when cultivated on gelatine,
+gave rise to tough warty colonies about 1/40 in.
+diameter, and was regarded as one of the lactic
+acid bacteria found in milk which has been incubated
+at 77&deg; to 90&deg; F. and afterwards incubated
+at a higher temperature, 100&deg; to 104&deg; F. Scholl<a name="FNanchor_54" id="FNanchor_54"></a><a href="#Footnote_54" class="fnanchor">54</a>
+isolated three different organisms, of which a yeast
+inverted milk sugar for the lactic acid bacteria,
+while <i>Dispora</i> peptonised the albuminoid matters.</p>
+
+<p><span class='pagenum'><a name="Page_92" id="Page_92">92</a></span></p><p>Adametz<a name="FNanchor_55" id="FNanchor_55"></a><a href="#Footnote_55" class="fnanchor">55</a> failed to isolate <i>Dispora</i>, and came to
+the conclusion that ordinary lactic bacteria and
+yeasts played the most important part in the
+fermentation.</p>
+
+<p>Essaulow found in keffir grains six different
+organisms&mdash;yeast cells, cocci, short thick bacilli,
+bent bacilli, long threads, and motile bacteria.
+The two latter would seem to be <i>Bacillus subtilis</i>,
+while the others may be regarded as <i>Bacterium
+acidi lactici</i> (Hueppe), <i>Bacterium a&euml;rogenes</i>, and
+<i>Streptococcus lacticus</i> (Grotenfeldt). Pure cultures
+were insufficient to produce keffir, while
+mixed cultures of <i>Bacterium acidi lactici</i> and yeasts
+were effective.</p>
+
+<p>Freudenreich,<a name="FNanchor_56" id="FNanchor_56"></a><a href="#Footnote_56" class="fnanchor">56</a> to whom we owe a record of
+very carefully executed experiments, could not
+arrive at a satisfactory explanation of the r&ocirc;le of
+<i>Bacillus caucasicus</i>. This organism is described
+as being 5-6 &micro; long and 1 &micro; thick, slightly motile,
+and possessing bright refractive spots at the
+poles of the bacilli. It is extremely difficult to
+cultivate, and forms flat, small greyish colonies
+of irregular outline. The bright refractive spots
+above referred to are, however, granules taking
+<span class='pagenum'><a name="Page_93" id="Page_93">93</a></span>the usual stains quite readily, and not spores as
+supposed by Kern.</p>
+
+
+<p>Freudenreich also found three other organisms&mdash;a
+yeast and two streptococci. The yeast, to
+which he gave the name <i>Saccharomyces</i> (Torula)
+<i>keffir</i>, forms small oval or roundish cells 2-3 &micro;
+wide and 3-5 &micro; long. The optimum temperature
+would seem to be about 72&deg; F.; the maximum 82&deg;
+F. This organism is unable to ferment milk
+directly, but is able to decompose maltose and
+glucose with gas production. It does not coagulate
+milk, but imparts to it a characteristic taste
+and is unable to withstand desiccation for more
+than a few days.</p>
+
+<p>Of the two streptococci isolated, <i>Streptococcus
+a</i> resembles organisms of the group <i>Streptococcus
+lacticus</i> in appearance, but is able to ferment milk,
+with weak acid and gas production, and is capable
+of inducing coagulation.<br /><br /></p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig11" id="fig11"></a><img src="images/fig11.jpg" width="500" height="494" alt=
+"Section through a Kephir Grain"
+title="" />
+
+<p class="center"><span class="smcap">Fig.</span> 11.&mdash;Section through a Kephir Grain.</p></div>
+
+<p>Contrary to what one would expect in an organism
+existing in keffir grains, this streptococcus is as
+little able to withstand desiccation as the above-mentioned
+yeast. <i>Streptococcus b</i> forms smaller
+cells as well as smaller colonies than <i>Streptococcus a</i>,
+but produces more lactic acid and more gas, and
+retains its vitality after desiccation. The relation
+<span class='pagenum'><a name="Page_94" id="Page_94">94</a></span>
+of these four organisms is, according to E. von
+Freudenreich, as follows: <i>Sacch. keffir</i> is unable
+to ferment directly milk or lactose, so that its
+growth must be preceded by that of <i>Streptococcus
+b</i>. <i>Streptococcus a</i> does not seem to play this part,
+but, unlike <i>Streptococcus b</i>, is able to coagulate
+milk on its own account. By the combined
+action of the yeast and the two streptococci,
+then, milk can be coagulated, milk sugar inverted,
+acid and gas produced by the streptococci, while
+gas and alcohol are formed by the activity of the
+yeast. The r&ocirc;le of <i>Bacillus caucasicus</i> is unknown,
+but it would seem to play a part in the
+formation of the keffir grain itself. By means
+of mixed cultures of the above organisms Freudenreich
+was successful in obtaining a fermented
+product possessing in all respects the characteristic
+properties of normal keffir. On the other
+hand, experiments to induce the formation of
+keffir grains gave negative results, but in this
+respect the cultural characteristics of <i>Lactobacillus
+keffir</i> would seem to give promise of success
+in the synthesis of the keffir grain. Fig. 11 is a
+photo-micrograph of an extremely thin section
+through a keffir grain, after a preceding treatment
+with saffranin. The matrix is composed entirely
+<span class='pagenum'><a name="Page_95" id="Page_95">95</a></span>of long thin bacilli (<i>Bacillus caucasicus</i>), while
+the peripheral portions, which are more deeply
+stained, consist to a large extent of dense masses
+of yeast cells with occasional streptococci. In a
+normal grain the latter organisms are present on
+the surface or in the cavities and grooves of the
+grain, and only to a less extent in the matrix.
+Nikolaiewa<a name="FNanchor_57" id="FNanchor_57"></a><a href="#Footnote_57" class="fnanchor">57</a> claimed to have isolated a hitherto
+unknown bacillus capable of coagulating milk
+by acid production, <i>Bacterium caucasicum</i>, not
+identical with, but related to Freudenreich's
+<i>Bacillus caucasicus</i>, and also a torula. Although
+no experiments were carried out, Nikolaiewa
+asserts that this organism forms the matrix of the
+grains. He was able to produce a beverage
+resembling keffir, just as Freudenreich and Essaulow
+did with entirely different organisms, but his
+product would appear to have been slightly too
+acid and to have lacked the characteristic aroma of
+the normal product. In the course of an extensive
+series of experiments Kuntze<a name="FNanchor_58" id="FNanchor_58"></a><a href="#Footnote_58" class="fnanchor">58</a> found the
+following organisms:</p>
+
+<div class="blockquot3"><p class="indent4">(<i>a</i>) True lactic acid forming bacteria, <i>Streptococcus
+acidi lactici</i> (Grotenfeldt).</p>
+
+<p><span class='pagenum'><a name="Page_96" id="Page_96">96</a></span></p>
+
+<p class="indent4">(<i>b</i>)
+Bacteria of the group <i>Bacterium acidi lactici</i>
+(Hueppe) and <i>Bacterium lactis a&euml;rogenes</i>.</p>
+
+<p class="indent4">(<i>c</i>) Various torula and yeast species.</p>
+
+<p class="indent4">(<i>d</i>) Two species of butyric acid bacteria, <i>Bacillus
+esterificans</i> and <i>Bacillus keffir</i> (Kuntze).</p></div>
+
+<p>His conclusions are: 1. In any case the presence
+of a yeast capable of directly fermenting
+milk sugar is not essential. 2. The significance of
+the presence of yeast lies in the fact that stimulation
+of the lactic bacteria occurs; further, the yeast
+exerts a regulating influence upon the rapidity of
+the fermentation proper. The variety is of minor
+importance, provided always that the yeast does
+not produce an unpleasant flavour. By the use
+of mixed cultures of <i>Bacillus esterificans</i>, <i>Bacillus
+keffir</i>, and <i>Streptococcus acidi lactici</i>, and a keffir
+yeast, Kuntze obtained a product that possessed
+to the fullest degree all the characteristic properties
+of a normal keffir. In such cultures he was successful
+in obtaining the formation of keffir-like
+grains. Keffir fermentation is, according to Kuntze,
+the result of the action of various organisms.
+During the initial stage butyric acid fermentation
+takes place, but is prevented from becoming
+predominant by the action of the keffir yeast.
+Simultaneously a true lactic acid fermentation
+proceeds and eventually gives place to a subsequent
+<span class='pagenum'><a name="Page_97" id="Page_97">97</a></span> secondary production of butyric acid.
+Finally, then, we have a certain amount of unison
+in the results obtained by Freudenreich, Essaulow,
+Nikolaiewa, and Kuntze. These show that, for
+the production of a characteristic keffir, specific
+organisms are not essential, provided always that
+those used possess, either individually or collectively,
+the essential capacity of acidifying, coagulating,
+and fermenting the milk. For the growth
+of normal grains the presence of a matrix-forming
+organism, such as <i>Bacillus keffir</i>, is indispensable.<br /><br /></p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig12" id="fig12"></a><img src="images/fig12.jpg" width="500" height="512" alt=
+"Streptococcus lacticus (Grotenfeldt) Growing on Lactose-Agar, Stained by Gram's Method"
+title="" />
+
+<p class="caption"><span class="smcap">Fig.</span> 12&mdash;<i>Streptococcus lacticus</i> (Grotenfeldt) growing on lactose-agar,
+stained by Gram's method. ( &#10005; 900 diams.)</p></div>
+
+<p><i>Diseases of Keffir Grains.</i>&mdash;According to the age
+and the previous treatment to which keffir grains
+have been subjected, the vitality of one or more
+of the organisms constituting the grain may have
+been impaired. The results of Freudenreich have
+shown that <i>Saccharomyces keffir</i> and <i>Streptococcus
+a</i> are unable to withstand desiccation for more
+than a few days, and this is sufficient to account
+for the frequent failures to obtain normal keffir
+from the grain. Further, grains succumb to a
+mucilaginous disease; the cavities become filled
+with a slimy fluid, and the grains are covered with
+mucilaginous matter. They lose their elasticity
+and become brittle or mealy, but large grains
+appear to be more subject to this fault than do
+<span class='pagenum'><a name="Page_98" id="Page_98">98</a></span>
+the small ones. Such grains should be disinfected
+by immersion for a short time in two per cent.
+salicylic acid solution, followed by drying in
+the sun, whereby they are completely regenerated.</p>
+
+<p>Another disease consists in the predominance of
+certain butyric acid bacteria which impart an
+unpleasant rancid taste to the keffir (Podowyssozki).
+This is generally attributed to the use
+of rich milk, or too high a temperature during
+preparation.</p>
+
+<p><i>Koumiss.</i>&mdash;Another product of the combined
+action of lactic acid and alcohol-producing organisms
+is called koumiss, kumys, milk-wine, lac
+fermentation, or vinum lactis. In the steppes of
+Southern Russia and Asia, as we have seen,<a name="FNanchor_59" id="FNanchor_59"></a><a href="#Footnote_59" class="fnanchor">59</a> it
+is prepared chiefly from mares' milk, but occasionally
+from that of camels and jennets. The name
+is said to be derived from that of a tribe mentioned
+by Xenophon and Pliny, viz., the Kumanen, by
+whom its preparation was practised. After the
+war with the Tartars in 1215 its use was adopted
+by the latter people, and eventually spread to the
+Turkomanen, Kalmucks, Khirgiz, Mongolians, etc.</p>
+
+<p>Rubruck, in 1253, records the use of a fermented
+drink&mdash;kosmos&mdash;prepared from mares' milk, and
+<span class='pagenum'><a name="Page_99" id="Page_99">99</a></span>about the same time Marco Polo mentions the
+occurrence of a milk-wine, chumis or chemius,
+among the Tartars. The fact that the Tartars
+were seldom ill, and were almost invariably free
+from lung troubles, led to an influx of visitors
+from surrounding countries, until finally its use
+spread to Russia, Austria, and Germany. At
+the present time the best koumiss is that produced
+in the province of Orenburg; but specially equipped
+koumiss establishments, under the control of
+physicians, exist in Odessa, Samara, Ufa in the
+Urals, and other districts. The curative properties
+of koumiss have long been recognised and its
+use is indicated in cases of indigestion, chlorosis,
+scurvy, tuberculosis, etc.</p>
+
+<p>Rubinsky states that, among the nomadic tribe,
+of Khirgiz and Kalmucks, a special leathern bottle
+(Turssuk, Orroth, or Soaba) is used for the preparation
+of koumiss, while wooden tubs (Tschiljak)
+similar in shape to the old-fashioned churn are
+used by the Bashkirs, and in koumiss establishments.</p>
+
+<p>The fermentation is induced by the addition
+of koumiss to fresh mares' milk, in proportions
+which vary according to the cleanliness observed
+in the actual preparation. Where the process
+<span class='pagenum'><a name="Page_100" id="Page_100">100</a></span>
+is carefully controlled, one part of koumiss to
+ten parts of milk is often used, but where gross
+infection from outside sources takes place one
+part of koumiss to three parts of milk is taken.
+The mixture is stirred at frequent intervals, and
+stored at a temperature of 73&deg;-90&deg; F. Weak
+koumiss is obtained after twenty to twenty-four
+hours in winter and twelve to fourteen hours in
+summer, but is scarcely ever consumed immediately,
+as it possesses a strong purgative action.</p>
+
+<p>It is generally poured into bottles (bottled koumiss);
+or allowed to remain in the tubs (tschiljak
+koumiss); in the former case the fermentation
+is ana&euml;robic, in the second it is a&euml;robic.</p>
+
+<p>Storage of the koumiss upon ice or in a cellar
+is necessary since medium koumiss is converted
+to strong koumiss in twelve to sixteen hours at
+ordinary temperatures, while at the lower temperature
+this occurs only in two to four days.<a name="FNanchor_60" id="FNanchor_60"></a><a href="#Footnote_60" class="fnanchor">60</a></p>
+
+<p>According to Biel,<a name="FNanchor_61" id="FNanchor_61"></a><a href="#Footnote_61" class="fnanchor">61</a> either old koumiss or the
+dried sediment from old koumiss may be used for
+the initial inoculation.   It may also be prepared
+by the repeated inoculation of mares' milk with
+soured cows' milk until a fermenting product is
+<span class='pagenum'><a name="Page_101" id="Page_101">101</a></span>obtained. Koumiss may be prepared by a method
+stated by Allik<a name="FNanchor_62" id="FNanchor_62"></a><a href="#Footnote_62" class="fnanchor">62</a> to be in general use in the Caucasian
+health-resorts. One part of beer-yeast is
+added to four to ten parts of fresh mares' milk
+(according to the strength of product required),
+and after thorough mixture of the two liquids the
+whole is allowed to ferment at a temperature of
+70&deg; to 72&deg; F. for two days. One part of this first
+product is then added to five parts of fresh cold
+milk, and allowed to stand three to four hours
+at 75&deg; to 77&deg; F. It is then poured into bottles,
+and after the expiration of another three to four
+hours is stored away in a cellar at about 45&deg; F.
+This koumiss may be used at any time from one
+to five days (generally two to three) after bottling
+according to the strength desired or prescribed
+in each individual case.</p>
+
+<p>The changes undergone during fermentation
+consist in a vigorous gas and acid production
+accompanied by alcohol formation and coagulation
+of the milk. The coagulum exists in an extremely
+fine state of division, and the liquid froths violently
+on the bottle being opened. It has a full pleasant
+acid taste, but should not contain more than one
+per cent. acid and two per cent. alcohol. The
+<span class='pagenum'><a name="Page_102" id="Page_102">102</a></span>specific gravity of koumiss is 1.008 to 1.020 at
+60&deg; F. Appended is an analysis of two different
+samples of koumiss:<br /><br /></p>
+
+<table width="80%" summary="koumiss" border="0">
+<tr>
+<td class="ko50t">&nbsp;</td>
+<td class="ko25at" colspan="2">Prepared from</td>
+</tr>
+<tr>
+<td class="ko50t">&nbsp;</td>
+<td class="ko25at">Mares' Milk.</td>
+<td class="ko25at">Separated&nbsp;&nbsp;&nbsp;<br />Cows' Milk.</td>
+</tr>
+<tr>
+<td class="ko50t">&nbsp;</td>
+<td class="ko25at">Per Cent.&nbsp;&nbsp;</td>
+<td class="ko25at">Per Cent.&nbsp;&nbsp;</td>
+</tr>
+<tr>
+<td class="ko50">Water</td>
+<td class="ko25">91.535</td>
+<td class="ko25">88.933</td>
+</tr>
+<tr>
+<td class="ko50">Fat</td>
+<td class="ko25">1.274</td>
+<td class="ko25">0.854</td>
+</tr>
+<tr>
+<td class="ko50">Nitrogenous bodies</td>
+<td class="ko25">1.913</td>
+<td class="ko25">2.025</td>
+</tr>
+<tr>
+<td class="ko50">Sugar</td>
+<td class="ko25">1.253</td>
+<td class="ko25">3.108</td>
+</tr>
+<tr>
+<td class="ko50">Ash</td>
+<td class="ko25">0.293</td>
+<td class="ko25">0.444</td>
+</tr>
+<tr>
+<td class="ko50">Carbon dioxide</td>
+<td class="ko25">0.876</td>
+<td class="ko25">1.027</td>
+</tr>
+<tr>
+<td class="ko50">Alcohol</td>
+<td class="ko25">1.850</td>
+<td class="ko25">2.647</td>
+</tr>
+<tr>
+<td class="ko50">Lactic acid</td>
+<td class="ko25">1.006</td>
+<td class="ko25">0.796</td>
+</tr>
+<tr>
+<td class="ko50">Glycerine</td>
+<td class="ko25">...</td>
+<td class="ko25">0.166</td>
+</tr>
+</table>
+
+<p>Fleischmann<a name="FNanchor_63" id="FNanchor_63"></a><a href="#Footnote_63" class="fnanchor">63</a> gives a formula for preparing
+an artificial koumiss from separated cows' milk,
+water, cane sugar, and milk sugar, with the addition
+of distillery yeast. Needless to say, this product
+must possess some of the characteristic by-flavour
+of the yeast employed, and is less suitable than
+koumiss prepared by the aid of a lactic yeast.
+Schipin investigated the fermentation of koumiss
+and found three distinct organisms.</p>
+
+
+<p>Rubinsky in a recent article threw much light
+on the phenomena of koumiss fermentation.
+<span class='pagenum'><a name="Page_103" id="Page_103">103</a></span>According to him, koumiss contains almost invariably
+four different organisms, viz., koumiss
+yeast, koumiss bacterium (<i>Lactobacillus</i>), <i>Streptococcus
+lactis</i> (Lister), <i>Bacterium a&euml;rogenes</i>, and
+occasionally <i>Bact. caucasicum</i> (Nikolajewa). For
+the preparation of normal koumiss only the two
+former organisms are required; they exceed in
+number any of the other organisms whose presence
+in the dairy is unavoidable. The presence
+of the two latter organisms is favourable to the
+production of good koumiss, as, by inducing a
+preliminary lactic fermentation, they tend to
+inhibit the growth of undesirable extraneous
+bacteria, etc. In medium and strong koumiss
+they die out on account of the amount of lactic
+acid formed (1%).</p>
+
+<p>Koumiss yeast possesses strongly differentiated
+protoplasm, but lacks any cultural characteristics.
+Abundant growth occurs in milk, and lactic acid
+(0.3%), alcohol, carbon dioxide, albumens and
+peptones, volatile acids, and aromatic substances
+are formed.</p>
+
+<p>Koumiss bacterium is related to the <i>Lactobacillus</i>
+of various other fermented milks, and is similar
+to <i>Bac. acidophilus</i>, and possesses like these a
+distinct polymorphism (branched cells, long and
+<span class='pagenum'><a name="Page_104" id="Page_104">104</a></span>
+short bacilli, etc.). It is non-sporogenous, has an
+optimum temperature of 90&deg; to 97&deg; F., and possesses
+cultural characteristics similar to those of
+the rest of the <i>Lactobacilli</i>.</p>
+
+<p>The by-products of koumiss yeast appear
+to favour the growth of the koumiss bacterium,
+as this organism, like the other <i>Lactobacilli</i>, is
+favourably influenced by the presence of small
+quantities of peptone, alcohol, and acid.</p>
+
+<p>The organisms found by Schipin consisted of a
+species of <i>Saccharomyces</i> and two bacilli, <i>Bacillus
+acidi lactici</i> and a non-sporulating bacillus. The latter
+organisms coagulate milk at 98&deg; F., but not
+at room temperature, and although a minute description
+of cultural characteristics is not given it
+would seem to be related to <i>Bacillus</i> or <i>Lactobacillus
+caucasicus</i>.</p>
+
+<p><i>Leben Ra&iuml;b</i> or <i>Leben</i> (<i>Laban.</i>)&mdash;This is a beverage
+prepared largely by the Egyptians, and
+differs from keffir, as does matzoon, in possessing
+a characteristic aroma and taste. It differs also
+from the former by having only a very weak
+alcoholic fermentation, and by the coagulum
+being coarse and lumpy instead of being extremely
+fine. It is made from buffaloes', goats', or cows'
+milk by the addition of roba (or old leben) to the
+<span class='pagenum'><a name="Page_105" id="Page_105">105</a></span>
+previously boiled and cooled fresh milk. The
+use of leben is many centuries old, and it is used
+in Egypt as in Arabia for medicinal purposes,
+although that of the Syrians and Arabians is said
+to differ from that of the Egyptians and Algerians.
+The fermentative changes occurring in the formation
+of the Egyptian leben have been investigated
+by Rist and Khoury,<a name="FNanchor_64" id="FNanchor_64"></a><a href="#Footnote_64" class="fnanchor">64</a> and also by Guerbet,<a name="FNanchor_65" id="FNanchor_65"></a><a href="#Footnote_65" class="fnanchor">65</a>
+who found that five organisms were normally
+present. These comprised a chain-forming bacillus
+(<i>Streptobacillus</i>), a second smaller bacillus
+(<i>Bacillus lebenis</i>), a diplococcus, a saccharomyces,
+and a mycoderma. Of these five organisms, it
+would appear that four live in metabiosis, the
+streptobacilli and bacilli hydrolyse the milk sugar,
+the components of which are split up by the yeast
+to alcohol and carbon-dioxide. The alcohol thus
+formed, together with the glucose formed by
+hydrolysis, are eventually converted to acid or
+combusted by the mycoderma species. The leben
+thereby assumes the sharp, unpleasant flavour
+met with in old samples. The diplococcus merely
+produces acidification and coagulation of the milk.
+Rist and Khoury were able, by the use of these
+<span class='pagenum'><a name="Page_106" id="Page_106">106</a></span>organisms, to produce normal leben, especially
+when the true yeast was allowed to grow in the
+milk for some time before inoculation with the
+other organisms was made.</p>
+
+<p>Some of the half-civilised tribes of Siberia, the
+Tartars and the Burgaten, prepare a strong
+alcoholic beverage, arak&agrave; or ojr&agrave;n, from fermented
+milk. This is really a product of distillation, and
+contains seven to eight per cent. of alcohol and
+volatile fatty acids.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig13" id="fig13"></a><img src="images/fig13.jpg" width="500" height="496" alt=
+"Photo-micrograph of preparation from Armenian
+soured milk" title="" />
+
+<p class="indent2"><span class="smcap">Fig.</span> 13&mdash;Photo-micrograph of preparation from Armenian
+soured milk (Matzoon). This is related to Yoghourt,
+and contains, as will be seen from the above photo,
+yeasts, streptococci, diplococci, and a bacillus with
+the morphology of <i>Bacillus bulgaricus.</i> This, and
+similar foods, owe their peculiar properties primarily
+to the presence of <i>Bacillus bulgaricus</i> (type A, White
+and Avery), and only in a lesser degree to the yeasts
+and lactic streptococci.</p></div>
+
+<p><i>Matzoon.</i>&mdash;This is a drink used largely in
+Western Asia, and is similar in character to keffir,
+but has a peculiar taste which distinguishes it
+from all other fermented milks. According to
+Weigmann,<a name="FNanchor_66" id="FNanchor_66"></a><a href="#Footnote_66" class="fnanchor">66</a> it is prepared from buffaloes', goats',
+or cows' milk, and is used partly as a means of
+souring milk for butter-making and also as a lactic
+food, eaten with spoons. In the same way buttermilk
+produced from milk which has been previously
+ripened by matzoon is used as a beverage. Finally,
+the coagulum (<i>than</i>) of such buttermilk is
+strained off, and, after being pressed, is mixed
+with meal and dried by exposure to the sun's
+rays. The preparation of matzoon is in many
+<span class='pagenum'><a name="Page_107" id="Page_107">107</a></span>respects very similar to that of keffir and koumiss,
+but differs by inducing a comparatively weak
+alcohol fermentation. In common, too, with yoghourt,
+the prevailing temperature is much higher
+than is required for keffir and koumiss.</p>
+
+<p>In regard to the biology of matzoon, the occurrence
+of various organisms has been recorded.
+Emmerling<a name="FNanchor_67" id="FNanchor_67"></a><a href="#Footnote_67" class="fnanchor">67</a> isolated, in addition to a yellow pigment-forming
+organism, <i>Bacillus subtilis</i>, <i>Bacillus
+lactis acidi</i>, and several fungi, a small
+micrococcus capable of hydrolysing milk- and cane-sugar.
+The organism produces and without gas
+formation, or peptonisation of the medium. Of
+the nine yeasts isolated from matzoon by Lindner<a name="FNanchor_68" id="FNanchor_68"></a><a href="#Footnote_68" class="fnanchor">68</a>
+and Kalantharianz,<a name="FNanchor_69" id="FNanchor_69"></a><a href="#Footnote_69" class="fnanchor">69</a> three were able to ferment
+milk sugar without previous hydrolysis, while
+two others, by the simultaneous production of
+lactic acid and fruit esters, gave to the matzoon
+its characteristic taste and aroma.</p>
+
+<p><i>Yoghourt and Soured Milk.</i>&mdash;Yoghourt is another
+fermented milk, and is related to the matzoon of
+Armenia, the gioddu of Sardinia, and the leben
+of Egypt. After a preceding boiling and reduction
+<span class='pagenum'><a name="Page_108" id="Page_108">108</a></span>of the volume of the milk, inoculation of the mass
+is made by the addition of a small quantity of
+old culture, and it is then allowed to sour at a
+comparatively high temperature. A moderately
+compact, jelly-like coagulum is thus formed, while
+keffir and koumiss possess a liquid consistency.
+The fermentation necessary for the two latter
+products only proceeds, too, at a much lower
+temperature, at which yeasts play an important
+part. According to Guerbet, yoghourt incubated
+for ten hours at 113&deg; F. contained 0.34 per cent.
+lactic acid and 0.012 per cent. alcohol. Luerssen
+and K&uuml;hn<a name="FNanchor_70" id="FNanchor_70"></a><a href="#Footnote_70" class="fnanchor">70</a> came to the conclusion that yoghourt
+contained chiefly a mixture of <i>Bacillus bulgaricus</i>,
+diplostreptococci, and a "granule" bacillus, so
+called on account of its granulated appearance
+after treatment with methylene blue. According
+to these authors, the first two organisms were
+found in each of eight samples of maya (young
+yoghourt) and of yoghourt itself, but the occurrence
+of the "granule" bacillus in plate cultures was
+by no means regular. In addition, yeasts were
+found in almost every sample examined, but were
+regarded more as accidental infections rather than
+as essential to the formation of a typical product.
+<span class='pagenum'><a name="Page_109" id="Page_109">109</a></span>The combined action of the three organisms
+already mentioned gave rise to a product closely
+resembling normal yoghourt. Piorkowski<a name="FNanchor_71" id="FNanchor_71"></a><a href="#Footnote_71" class="fnanchor">71</a> subjected
+Bulgarian maya to examination and associated
+himself with Metchnikoff<a name="FNanchor_72" id="FNanchor_72"></a><a href="#Footnote_72" class="fnanchor">72</a> in finding three
+species, a streptococcus, a diplococcus, and a
+specific organism to which he gave the name
+<i>Yoghourt bacillus</i>. Similar results were also obtained
+by Grigoroff.<a name="FNanchor_73" id="FNanchor_73"></a><a href="#Footnote_73" class="fnanchor">73</a> Piorkowski's <i>Yoghourt bacillus</i>
+is similar in form to <i>Bacillus subtilis</i>, but does
+not sporulate, nor does it liquefy gelatine. Young
+individuals are stained by Gram's method; older
+individuals are, however, Gram negative. The optimum
+temperature is 112&deg; F. Kuntze attempted
+to isolate the organisms mentioned by Luerssen
+and K&uuml;hn, and by plate culture procured growth
+of a spore-forming bacillus similar to Weigmann's
+<i>Bacillus matzoon</i>. To this organism is attributed
+the power to impart a specific taste to the matzoon,
+but as growth is comparatively slow, it can only
+be of significance in determining the quality of
+the curd and cheese prepared from this product.
+Cultures were also obtained which resembled in
+general character those of the organism described
+<span class='pagenum'><a name="Page_110" id="Page_110">110</a></span>by Luerssen and K&uuml;hn as <i>Bacillus bulgaricus</i> and
+named by Kuntze <i>Bacterium W</i>. Granule formation
+was transient in this culture, and the
+organisms eventually became inactive. Further
+analysis of maya gave cultures of the "granule"
+bacillus, but these passed over from the type
+forming irregular colonies (see Figs. 14, 15, 16)
+to that producing smooth colonies. Further,
+although the granule formation persists largely
+in milk, the organisms soon revert to the non-granular
+type if cultivated on agar. By the use
+of the Gram-Weigert stain organisms from a
+several-days-old culture on beer-wort-agar gave
+an interesting reaction. The bacillar threads are
+in places Gram-negative, in others Gram-positive,
+and bear small club-like swellings (see Fig. 14).
+Results similar to these were also obtained with
+cultures of <i>Bacillus matzoon</i> (Weigmann and
+Gr&uuml;bner) and also with <i>Bacillus acidophilus</i>.</p>
+
+<p>Neisser's method of staining failed to give such
+good effects by the examination of fresh maya,
+as did an alcoholic aqueous solution of methylene
+blue in showing up the granules of the organisms.
+Again, Grixoni<a name="FNanchor_74" id="FNanchor_74"></a><a href="#Footnote_74" class="fnanchor">74</a> found, but did not isolate, a
+similar granule-forming organism (<i>Bacterium sardous</i>)<span class='pagenum'><a name="Page_111" id="Page_111">111</a></span>
+in Sardinian gioddu. As already mentioned
+in the description of leben, Rist and Khoury
+found a long bacillar lactic ferment (<i>Streptobacillus
+lebenis</i>) which also exhibited the irregular greyish
+white hairy colonies and high optimum temperature
+characteristic of this group. On account
+of the similarity in form, staining reactions, temperature
+requirements, and cultural growth of
+the organisms described by Emmerling, D&uuml;ggeli,
+Weigmann, Grixoni, and Rist and Khoury, Kuntze
+is inclined to regard them as belonging to one single
+group of lactic ferments. According to him the
+granule formation is rather variable, and may be
+induced or suppressed by cultural methods. Not
+only do organisms of this group produce far more
+acid than the normal lactic bacteria; they are
+also more resistant to acid, and are able to develop
+in milk to which 0.5 per cent. hydrochloric acid
+has been added. A comparatively high percentage
+of alcohol seems to encourage growth, and this
+was obtained in milk containing 4 per cent. alcohol.
+This would no doubt tend to explain the
+phenomenon observed by Kuntze that milk is not
+so rapidly fermented by organisms of this group
+as when cultures of diplococci and yeasts are
+added. Since organisms of this group would
+<span class='pagenum'><a name="Page_112" id="Page_112">112</a></span>
+seem to be widely distributed, the question of
+their natural habitat arises. Luerssen and K&uuml;hn
+were unsuccessful in their search for such organisms
+in K&ouml;nigsberg milk, but Leichmann records
+the occurrence of a long bacillus (<i>Bacillus lactis
+acidi</i>) in milk that had spontaneously soured at
+112&deg; to 120&deg; F. This organism, too, showed
+characteristic growth on agar media, and produces
+l&aelig;vo-rotatory lactic acid. The examination
+of calves' stomachs showed, according to Kuntze,
+only occasional long bacilli, but inoculation of
+sterile milk and incubation at 100&deg; F. with repeated
+over-inoculation gave a culture showing the
+characteristic granule reaction (see Figs. 18 and 20).
+Although plate cultures made direct from calves'
+stomachs do not exhibit the regular contours
+generally shown by the granule bacillus, yet this
+growth may be induced by preceding cultivation
+in lactose bouillon to which 0.5 per cent. acetic
+acid has been added. A similar organism, <i>Bacillus
+acidophilus</i>, was isolated from calves' manure
+by means of this acetic bouillon, as was also a
+diplostreptococcus which resembled very closely
+the typical lactic acid streptococcus. This resemblance
+was made all the more striking by the fact
+that they were capable of coagulating milk at a
+<span class='pagenum'><a name="Page_113" id="Page_113">113</a></span>temperature of 99&deg; to 104&deg; F. Since these organisms
+are present in large numbers in manure and
+also in the digestive tract of ruminants, it would
+seem probable that their occurrence is not without
+significance for the operations of cheese manufacture.
+According to Jensen, the practice of
+applying farmyard manure to Swiss meadows
+has been regarded as absolutely essential to the
+production of cheese of the best quality; while,
+on the other hand, the application of artificial
+manures would seem to have been responsible
+for an increase in abnormal cheese. K&uuml;ntze
+found further that by the combined inoculation of
+sterile milk with the diplostreptococcus and the
+"granule" bacillus from calves' stomachs, together
+with a yoghourt yeast, he was able to obtain
+a product possessing a taste and aroma little
+different from normal yoghourt. During their
+investigations upon the ripening of Swiss hard
+cheese, Freudenreich and Jensen<a name="FNanchor_75" id="FNanchor_75"></a><a href="#Footnote_75" class="fnanchor">75</a> isolated five
+varieties of lactic acid bacilli, and were able to
+show that one of these, especially <i>Bacillus casei &#949;</i>,
+was of the greatest importance for the production
+of good cheese. This organism has been found
+by Th&ouml;ni to be present in rennet tablets, while
+<span class='pagenum'><a name="Page_114" id="Page_114">114</a></span>a related variety, <i>Bacillus casei &#948;</i>, was found in
+fresh calves' stomachs. Unfortunately, staining
+tests with these organisms were not carried out,
+so that no data are available in regard to the
+presence of granules. The photo-micrographs of
+these organisms show the small clubs and true-branched
+forms. The presence of these diplococci
+and bacillar lactic ferments in the intestinal
+tract of ruminants and horses might possess some
+importance for the preparation of yoghourt in
+bags or tubes made from the stomachs of these
+animals. Finally, Moro<a name="FNanchor_76" id="FNanchor_76"></a><a href="#Footnote_76" class="fnanchor">76</a> has isolated an acidophilic
+organism from the dejecta of infants which
+resembles closely, both in manner of growth, resistance
+to acids, true branching, and temperature
+optimum, the granule bacillus and related forms.</p>
+
+
+
+<p>[This group of sixteen illustrations (Figs. 14 to 29), showing various
+aspects of the Yoghourt bacillus and others of a cognate nature, is taken
+from the <i>Centralblatt f&uuml;r Bakteriologie</i> of Jena.&mdash;L. M. D.]</p>
+
+<table width="100%" summary="Yoghourt bacillus" border="0">
+<tr>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig14" id="fig14"></a><img src="images/fig14.jpg" width="225" height="241" alt=
+"Granule Bacillus from Yoghourt. Shredded Preparation of a Fresh Skim-Milk Culture" title="" /></div></td>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig16" id="fig16"></a><img src="images/fig16.jpg" width="225" height="244" alt=
+"Granule Bacillus from Yoghourt. Agar Milk Sugar Culture" title="" /></div></td>
+</tr>
+<tr>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 14.&mdash;Granule Bacillus from
+Yoghourt. Shredded preparation of
+a fresh skim-milk culture at 37&deg; C. for
+six hours. Stain: aqueous methylene
+blue. (Enlarged 1:500.) In Figs.
+15 and 17 will be noticed the chain
+arrangement of the bacillus, which, in
+spite of the supposed data of Luerssen
+and Kuhn, will be generally noticed
+in the granule bacillus.</p></td>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 16.&mdash;Granule Bacillus from
+Yoghourt. Agar Milk Sugar Culture
+cultivated for forty-eight hours at 37&deg;
+C. Below is the true branching, above,
+the distorted involution form. This
+production of involution forms occurs
+chiefly in old cultures, and is an indication
+of degeneration. Stain: aqueous
+methylene blue. (Enlarged 1:700.)</p></td>
+</tr>
+<tr>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig15" id="fig15"></a><img src="images/fig15.jpg" width="225" height="233" alt=
+"Granule Bacillus from Yoghourt, Cultivated after the Usual Agar Method" title="" /></div></td>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig17" id="fig17"></a><img src="images/fig17.jpg" width="225" height="233" alt=
+"Bacteria W. from Milk, Cultivated Twenty-Four Hours" title="" /></div></td>
+</tr>
+<tr>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 15.&mdash;Granule Bacillus from
+Yoghourt, cultivated after the usual
+Agar method, for twenty-four hours
+at 37&deg; C. Stain: aqueous methylene
+blue. (Enlarged 1:500.)</p></td>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 17.&mdash;<i>Bacteria W.</i> from Milk,
+cultivated twenty-four hours at 37&deg;
+C. Methylene blue. (Enlarged
+1:500.) The similarity in the pictures
+ought to serve as a proof of the
+near relation of the granule form and
+non-granule varieties.</p></td>
+</tr>
+<tr>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig18" id="fig18"></a><img src="images/fig18.jpg" width="225" height="245" alt=
+"Agar Milk Sugar Culture. From the Original Bulgarian Yoghourt" title="" /></div></td>
+<td class="m50b">
+<div class="figcenter" style="width: 225px;"><a name="fig19" id="fig19"></a><img src="images/fig19.jpg" width="225" height="211" alt=
+"Agar Milk Sugar Culture. Surface Colony of Granule Bacillus from Calf's Stomach" title="" /></div></td>
+</tr>
+<tr>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 18.&mdash;Agar Milk Sugar Culture.
+From the original Bulgarian
+Yoghourt. In the centre, and beneath,
+the characteristic hairy
+irregular colonies of the granule
+bacillus (<i>Bacillus bulgaricus</i> group),
+to the left, the smooth contoured
+yeast colonies. The colonies of the
+former organism always remain
+microscopic in size. (Incubated
+several days at 20&deg; to 25&deg; C. Magnified
+X 10.)</p>
+</td>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 19.&mdash;Agar Milk Sugar Culture.
+Surface colony of granule bacillus from
+calf's stomach. The great resemblance
+this colony bears to those formed by the
+granule bacillus from Yoghourt will be
+apparent. This fact, as well as close
+agreement in other cultured features, induced
+K&uuml;ntze to place these organisms
+in one group. (Incubated two days at
+37&deg; C. Magnified X 100.)</p></td>
+</tr>
+<tr>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig20" id="fig20"></a><img src="images/fig20.jpg" width="225" height="251" alt=
+"Agar Milk Sugar Culture. Deep-Lying Colony of Granule Bacillus from Calf's Stomach" title="" /></div></td>
+<td class="m50b">
+<div class="figcenter" style="width: 225px;"><a name="fig21" id="fig21"></a><img src="images/fig21.jpg" width="225" height="227" alt=
+"Agar Milk Sugar. Colony of Bacterium W. from Yoghourt" title="" /></div></td>
+</tr>
+<tr>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 20.&mdash;Agar Milk Sugar Culture.
+Deep-lying colony of granule
+bacillus from calf's stomach. The
+form of the colony is often determined
+by the relative presence or
+absence of air. (Two days at 37&deg;
+C. Enlarged about 1:50.)</p></td>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 21.&mdash;Agar Milk Sugar. Colony
+of <i>Bacterium W.</i> from Yoghourt (non-granular
+variety of the granule bacteria,
+as far as possible identical with Luersen
+and Kuhn's <i>Bacillus bulgaricus</i>), of
+a cubical branching-out form.</p>
+<p>According to K&uuml;ntze, the granule
+formation of this and related organisms
+is variable, while White and Avery regard
+it as a constant characteristic.
+(Incubated two days at 37&deg; C. Magnified
+X 50.)</p>
+</td>
+</tr>
+<tr>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig22" id="fig22"></a><img src="images/fig22.jpg" width="225" height="214" alt=
+"Two Colonies of Bacillus Acidophilus from Calves' Manure" title="" /></div></td>
+<td class="m50b">
+<div class="figcenter" style="width: 150px;"><a name="fig23" id="fig23"></a><img src="images/fig23.jpg" width="150" height="169" alt=
+"Beer-wort Gelatine." title="" /></div></td>
+</tr>
+<tr>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 22.&mdash;Two colonies of <i>Bacillus
+acidophilus</i> from calf's manure. Agar
+Milk Sugar Culture. With this organism,
+also, we have conformation to one
+type of colony, while, in other respects,
+temperature requirements and production,
+etc., we have close agreement with
+the granule bacillus (<i>Bacillus bulgaricus</i>).
+(Two days at 37&deg; C. Enlarged about
+1:50.)</p></td>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 23.&mdash;Beer-wort Gelatine.
+Fourteen-days-old colony of Yoghourt
+yeast. (Enlarged about 1:50.)]</p></td>
+</tr>
+<tr>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig24" id="fig24"></a><img src="images/fig24.jpg" width="225" height="242" alt=
+"Shredded Preparation of Bulgarian Original Yoghourt" title="" /></div></td>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig25" id="fig25"></a><img src="images/fig25.jpg" width="225" height="245" alt=
+"Granule Bacillus from Yoghourt. Cultivated in Skim Milk in Twenty-Four Hours" title="" /></div></td>
+</tr>
+<tr>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 24.&mdash;Shredded preparation of
+the Bulgarian original Yoghourt.
+Stain: aqueous methylene blue.
+Granule bacillus, diplostreptococci,
+and yeast. (See also other photo-micrographs
+of Yoghourt. Enlarged
+1:70.)]</p></td>
+<td class="m50">
+<p><span class="smcap">Fig.</span> 25.&mdash;Granule Bacillus from
+Yoghourt. Cultivated in skim milk
+in twenty-four hours at 37&deg; C. Stain:
+aqueous methylene blue. (Enlarged
+1:50.)</p>
+<p>By means of this staining treatment
+the presence of granules (not spores)
+can be easily detected. Treatment
+with fuchsine fails to bring out these
+formations.</p></td>
+</tr>
+<tr>
+<td class="m50b">
+<div class="figcenter" style="width: 225px;"><a name="fig26" id="fig26"></a><img src="images/fig26.jpg" width="225" height="203" alt=
+"Bacteria W., Agar Milk Sugar Culture" title="" /></div></td>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig27" id="fig27"></a><img src="images/fig27.jpg" width="225" height="229" alt=
+"Bacteria acidophilus from Calves' Manure" title="" /></div></td>
+</tr>
+<tr>
+<td class="m50">
+<p><span class="smcap">Fig.</span>&nbsp;26.&mdash;<i>Bacteria W.</i>, Agar Milk
+Sugar Culture. Cultivated twenty-four
+hours (knobs, clubs). Stain: Gram's
+method coloured with aqueous fuchsine
+afterwards. (Enlarged 1:600.)</p></td>
+<td class="m50">
+<p><span class="smcap">Fig.</span>&nbsp;27.&mdash;<i>Bacteria acidophilus</i> from
+calves' manure, isolated by means of
+bouillon as acid as vinegar. Shredded
+out of the usual Agar culture.
+Twenty-four hours at 37&deg; C. Stain:
+aqueous methylene blue. (Enlarged
+1:700.)</p></td>
+</tr>
+<tr>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig28" id="fig28"></a><img src="images/fig28.jpg" width="225" height="266" alt=
+"Mucus from Calf's Stomach Inoculated into Milk after Eight Transferrings" title="" /></div></td>
+<td class="m50b">
+<div class="figcenter" style="width: 225px;"><a name="fig29" id="fig29"></a><img src="images/fig29.jpg" width="225" height="211" alt=
+"Diplostreptococcus from Yoghourt. Pure Culture in Skim Milk" title="" /></div></td>
+</tr>
+<tr>
+<td class="m50">
+<p><span class="smcap">Fig.</span>&nbsp;28.&mdash;Mucus from calf's stomach
+inoculated into milk after eight
+transferrings. Shredded preparation
+cultivated in milk for twenty-four
+hours at 37&deg; C. Diplostreptococci
+and granule bacillus. Stain: aqueous
+methylene blue. (Enlarged
+1:500.)</p></td>
+<td class="m50">
+<p><span class="smcap">Fig.</span>&nbsp;29.&mdash;Diplostreptococcus from Yoghourt.
+Pure culture in skim milk. A
+comparison of the illustrations will show
+how close a resemblance exists between
+bacteria found in the mucous membrane
+of calf's stomach and those occurring in
+Yoghourt. In fact, by the combined
+action of granule bacilli, and of diplostreptococci
+from calf's stomach, together
+with a Yoghourt yeast, it is possible to
+prepare normal Yoghourt.</p></td>
+</tr>
+
+</table>
+
+<p>In a review of the literature of the subject of
+soured milks, Makrinoff suggests the adoption
+of the two names, <i>Streptobac. lebenis viscosus</i> and
+<i>Streptobac. lebenis non-viscosus</i>, for the organisms
+of the so-called Bulgaricus group, and known at
+present as <i>Bacillus-bulgaricus</i>, <i>Streptobac. lebenis</i>,
+<i>Bacillus of Massol</i>, <i>Granule bacillus</i>, <i>Bact. Mazun</i>,
+<i>Bac. lactis acidi</i>, etc.<a name="FNanchor_77" id="FNanchor_77"></a><a href="#Footnote_77" class="fnanchor">77</a></p>
+
+<p><span class='pagenum'><a name="Page_115" id="Page_115">115</a></span></p>
+
+<p>White and Avery<a name="FNanchor_78" id="FNanchor_78"></a><a href="#Footnote_78" class="fnanchor">78</a> have made a comparative
+study of a large number of varieties and species
+of lactic acid bacteria of the above type obtained
+from various fermented milks and milk tabloids.
+Their descriptions are so detailed and their conclusions
+are so important that we give them at
+length. According to this work, the whole of the
+thermophilic lactic acid bacilli of the so-called
+Bulgaricus type may be divided into two sub-types,
+A and B.</p>
+
+
+<div class="center"><i>The Cultural Characteristics of the Bacillus Bulgaricus
+Group</i></div>
+
+<p>The cultural characteristics of all the strains
+of <i>Bacillus bulgaricus</i> (granule bacillus) are as
+follows:</p>
+
+<p><i>In Whey Agar.</i>&mdash;All strains exhibit wide variation
+in size, 2 &micro; to 50 &micro; long and about 1 &micro; broad.
+Almost all individuals are intensely Gram-positive,
+and show regularity of outline. All strains
+show involution form, exhibiting vacuoles, and
+often show empty cell membranes. The latter
+are Gram-negative, and vary greatly in both
+dimensions as well as in form. All strains show
+tendency to chain formation, some being arranged
+<span class='pagenum'><a name="Page_116" id="Page_116">116</a></span>in chains of six to twenty-five segments, which
+may contain both Gram-positive and Gram-negative
+individuals. Type B exhibits Gram-negative
+spherical bodies varying from 0.25 &micro; to 1 &micro; in
+size, adhering to the sides of some of the Gram-negative
+individuals.</p>
+
+
+<p><i>In Whey.</i>&mdash;In this medium there is a marked
+tendency toward degeneration and involution.
+In the early stages of incubation, at 100&deg; to 112&deg; F.,
+the bacilli are uniform in size and intensely Gram-positive;
+in succeeding stages the irregular, vacuolated,
+inflated, and ruptured forms predominate.
+Between the eighteenth and twenty-fourth hours
+of incubation at 112&deg; F. the strains of type A
+develop oval to kidney-shaped nodules attached
+to a stem extending from the cell substance.
+As the incubation is prolonged these nodules
+increase in size, often measuring 1 &micro; to 2 &micro; in
+length; this nodule formation occurs at the expense
+of the cell protoplasm, and appears to be
+a marked characteristic of growth in whey. Cultures
+of type B do not form nodules or clubs, but
+small spherical bodies more or less securely attached
+to the cell wall are seen. Again, type A
+assumes the form of small bacilli in chains, while
+type B strains develop to a greater length and
+<span class='pagenum'><a name="Page_117" id="Page_117">117</a></span>exist almost exclusively as single isolated forms.
+True branching has been observed in strains of
+type B.</p>
+
+<p><i>In Milk.</i>&mdash;In milk there is a tendency to thread-formation
+consisting of four to ten segments in
+the case of type A, while type B shows longer
+and more curved forms. With increasing age
+of the culture there also appears to be increase
+in the length of the organisms. All strains are
+non-motile, non-sporogenous, and non-capsule-forming.</p>
+
+<p>Staining Reactions.&mdash;All strains are readily
+stained by the usual aniline dyes.</p>
+
+<p><i>A. Gram's Method.</i>&mdash;Young individuals give an
+intense reaction with this stain; old bacilli are
+easily decolourised, and degenerate forms are
+always Gram-negative, while single individuals
+have been observed which showed gradation from
+one pole of the cell to the other.</p>
+
+<p><i>B. Loeffler's Methylene Blue.</i>&mdash;According to the
+behaviour of the organisms studied, a separation
+into two types appears possible, type A being
+uniformly impregnated, while type B shows distinct
+differentiation. The cell body is seen to
+contain a varying number of round to oval bodies
+or granules. This is the appearance already
+<span class='pagenum'><a name="Page_118" id="Page_118">118</a></span>
+mentioned by D&uuml;ggeli, Luerssen and K&uuml;hn, and
+Kuntze, and from which the granule bacillus
+derives its name. In opposition to the observations
+of Kuntze, the occurrence of granules
+was not found to be variable; it was, indeed, so
+constant as to constitute a distinguishing characteristic
+between the two types. The organisms
+of this group are difficult to cultivate, and freshly
+isolated growth is obtainable only on media containing
+whey, malt, or in milk. They grow
+equally well under a&euml;robic or ana&euml;robic conditions.
+The optimum temperature for growth is 113&deg; to
+115&deg; F.; growth is fair at 85&deg; F., slight at 75&deg; F.,
+and does not take place at 68&deg; F.</p>
+
+<p>Colonies on whey agar are round to irregular,
+greyish white, curled and filamentous, often
+streaming, and in a few cases smooth and even
+in structure. Gelatine is not liquefied. There is
+no surface growth on gelatine stab-cultures. Along
+the stab the growth is filiform, beaded, with
+subsequent horizontally projecting ramifications.
+Milk is coagulated in eight to eighteen hours at
+112&deg; F., and is the most favourable medium for
+growth.</p>
+
+
+<p>[I am indebted for this group of illustrations (seventeen
+in number) to the editor of <i>Bacteriotherapy,</i> New York,
+U.S.A.&mdash;L.M.D.]</p>
+
+<div class="figcenter" style="width: 400px;"><a name="fig30" id="fig30"></a><img src="images/fig30.jpg" width="400" height="395" alt=
+"Photo-Micrograph of Preparation Made from Yoghourt, Showing Yeast Cells" title="" />
+
+<p class="cap"><span class="smcap">Fig.</span> 30&mdash;Photo micrograph of preparation made from
+Yoghourt, showing yeast cells, large lactic diplococci,
+small slender bacilli and many large bacilli possessing the
+morphology of <i>Bacillus bulgaricus</i>. Yeast cells are almost
+invariably found in native Yoghourt, but do not appear
+to be essential to the production of a tropical beverage.
+Indeed, they would seem to be responsible for the unpleasant
+astringent taste often met with in old samples of this
+product.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="fig31" id="fig31"></a><img src="images/fig31.jpg" width="400" height="405" alt=
+"Photo-Micrograph of Smear from Greek Curdled Milk Called 'Giaourti'" title="" />
+
+<p class="cap"><span class="smcap">Fig. 31</span>&mdash;Photo micrograph of smear from Greek
+Curdled Milk called "Giaourti," and showing yeast cells,
+long bacilli and a mould (<i>Oidium lactis</i>), possessing very
+large elongate cells. The presence of the latter is very
+undesirable, as it rapidly combusts the lactic acid, digests
+the casein, and imparts a strong unpleasant cheesy flavour
+to the beverage.</p></div>
+
+<p><span class='pagenum'><a name="Page_119" id="Page_119">119</a></span></p>
+
+<p>Type A produces 2.7 per cent. to 3.7 per cent.
+inactive lactic acid in milk, while type B produces
+only 1.2 per cent. to 1.6 per cent. l&aelig;vo-rotatory
+lactic acid in milk. There is a small quantity
+of acetic, formic, and succinic acids formed.
+The conclusions of White and Avery are:</p>
+
+<p>I. A review of the morphological culture and
+biochemical features of the lactic acid producing
+bacilli from yoghourt, matzoon, and leben, appears
+to justify their classification as a single
+group.</p>
+
+<p>II. This group would seem to be identical
+with <i>Bacterium caucasicum</i> (Kern).</p>
+
+<p>III. The significant variations exhibited by
+these bacilli in regard to the presence or absence
+of granules demonstrable by differential stains,
+the degree of lactic acid production, and the nature
+of the acid produced, suggest a division into
+two different types&mdash;the true type A, and the
+paratype B.</p>
+
+<p>Quite recently Hastings and Hammer<a name="FNanchor_79" id="FNanchor_79"></a><a href="#Footnote_79" class="fnanchor">79</a> recorded
+the isolation from milk of an organism producing
+more acid than either <i>Bacterium coli commune</i> or
+<i>Bacillus lactis acidi</i>. It is characterised by possessing
+a high optimum temperature, and by the
+limited conditions under which it grows on nutrient
+<span class='pagenum'><a name="Page_120" id="Page_120">120</a></span>
+media. On this account these investigators
+suppose it to be related to those described in
+the paragraphs on fermented milks, leben, matzoon,
+etc., and which are regarded by Kuntze as
+being identical.</p>
+
+<p>Similarly Boutroux<a name="FNanchor_80" id="FNanchor_80"></a><a href="#Footnote_80" class="fnanchor">80</a> found 1.5 per cent. acidity
+produced in a solution containing albuminous
+matter and glucose; while Richet<a name="FNanchor_81" id="FNanchor_81"></a><a href="#Footnote_81" class="fnanchor">81</a> states that
+with the addition of gastric juice to milk as much
+as four per cent. acidity may be formed. After
+storing samples of milk for eight days at 100&deg; F.,
+Koning<a name="FNanchor_82" id="FNanchor_82"></a><a href="#Footnote_82" class="fnanchor">82</a> found 2.35 per cent. and 2.5 acid; while
+similar samples stored at 60&deg; to 62&deg; F. for the same
+period only developed 0.9 per cent. Heinemann<a name="FNanchor_83" id="FNanchor_83"></a><a href="#Footnote_83" class="fnanchor">83</a>
+records the production of 3.0 per cent. acid in
+milk incubated at 100&deg; F.; and Jensen states that
+<i>Bacillus casei &#949;</i> is capable of developing 2.7 per
+cent. lactic acid.</p>
+
+<p>Dr. H. B. Hutchinson, bacteriologist at Rothamsted
+Experimental Station, has also been
+successful in isolating a bacillus from English
+market milk resembling in every particular those
+classified by White and Avery as type A.</p>
+
+<table width="100%" summary="soured milk">
+<tr>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig32" id="fig32"></a><img src="images/fig32.jpg" width="225" height="216" alt=
+"Photo-Micrograph of Soured Milk Inoculated with a Tablet containing Viable and Pure Cultures of Bacillus bulgaricus" title="" /></div></td>
+<td class="m50">
+<div class="figcenter" style="width: 225px;"><a name="fig33" id="fig33"></a><img src="images/fig33.jpg" width="225" height="216" alt=
+"Photo-Micrograph of Milk Inoculated with a Ferment Table in which Bacillus bulgaricus is no Longer Viable" title="" /></div></td>
+</tr>
+<tr>
+<td class="m50">
+<p><span class="smcap">Fig.</span>&nbsp;32 is a photo-micrograph of soured milk inoculated
+with a tablet containing viable and pure cultures of <i>Bacillus
+bulgaricus</i>, and incubated for seventy-two hours. These
+tablets constitute a valuable means of preparing soured
+milk for therapeutic purposes.</p></td>
+
+<td class="m50">
+<p ><span class="smcap">Fig.</span>&nbsp;33 is a photo-micrograph of milk inoculated with a
+ferment tablet in which <i>Bacillus bulgaricus</i> is no longer
+viable, and the only growth obtained is that of an organism
+allied to the <i>Bacillus subtilis</i> (Hay bacillus) group. Such
+milk would be absolutely without value.</p></td>
+</tr>
+</table>
+<p><span class='pagenum'><a name="Page_121" id="Page_121">121</a></span></p>
+
+<p>It will thus be seen that organisms related to
+those of Oriental and Occidental milk beverages
+are present in conditions where it is impossible
+for them to attain to any active growth. The
+same class of organism has also been found in
+many cases in butter and cheese throughout the
+United States.</p>
+
+<p>Of recent years the consumption of milk fermented
+by these organisms has been introduced
+more or less successfully into all European countries.
+This custom is due, as we have seen,<a name="FNanchor_84" id="FNanchor_84"></a><a href="#Footnote_84" class="fnanchor">84</a>
+to a very great extent to the announcement of
+Metchnikoff<a name="FNanchor_85" id="FNanchor_85"></a><a href="#Footnote_85" class="fnanchor">85</a> that the action of such organisms
+in the alimentary tract conduce to a prolongation
+of life. Moro found that the dejecta of
+children contain large numbers of <i>Bac. lacidophilus</i>
+and <i>Bac. bifidus</i>, but, as age advances, the
+bacterial flora of the intestines tends to change.
+The number of acid-producing organisms gradually
+becomes less, and other bacteria capable of
+producing far-reaching decomposition of albuminoid
+matter tend to increase.</p>
+
+<p>Working on the assumption that senility is
+partially due to the absorption of by-products
+<span class='pagenum'><a name="Page_122" id="Page_122">122</a></span>formed from albuminoid food by the decomposing
+or putrefactive bacteria mentioned, Metchnikoff
+instituted a search for organisms capable
+of suppressing the growth of the putrefactive
+bacteria.</p>
+
+<p>It has long been known that milk allowed to
+become sour will keep for a considerably longer
+period in hot weather than if lactic bacteria had
+not grown. This preservative action of lactic
+acid also comes into play in the manufacture of
+sauerkraut and in the preservation of meat by
+immersion in sour milk.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig34" id="fig34"></a><img src="images/fig34.jpg" width="500" height="493" alt=
+"Photo-Micrograph of Smear of Culture of Bacillus bulgaricus"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 34.</span>&mdash;Photo-micrograph of smear of culture of <i>Bacillus bulgaricus</i>,
+recommended by Metchnikoff for use in cases of intestinal auto-intoxication.
+Unlike the ferments of normally soured milk, which are sometimes indifferent,
+or even injurious, in their action, this bacillus is capable of growth at blood
+heat, and, by producing much larger quantities of lactic acid than such organisms
+as <i>Streptococcus lacticus</i>, <i>Bacillus coli commune</i>, or <i>Bacteria lacticus aerogenes</i>,
+inhibits the multiplication of bacteria responsible for the putrefaction of
+albuminoid food in the intestines.</p></div>
+
+<p>Bienstock has shown that the growth of <i>Bac.
+putrificus</i> is inhibited by the action of <i>Bact. coli
+commune</i>, which is capable of setting up a slight
+lactic acid fermentation. <i>Bact. coli commune</i>,
+however, gives rise to substances of an injurious
+character, and, although present very abundantly
+in the intestinal tract, it may by reduced almost
+entirely by the active growth of lactic acid bacteria.
+This fact is of great value to the cheese-maker,
+since by the addition of a lactic acid
+culture (starter) to milk before renneting, gas-producing
+bacteria such as <i>Bact. coli</i> may be checked
+in growth. Since the ordinary lactic acid bacteria
+such as <i>Streptococcus lacticus</i>, <i>Bac. lactis acidi</i>,
+<span class='pagenum'><a name="Page_123" id="Page_123">123</a></span>and others, are incapable of growth at blood
+temperature, it appeared necessary to procure
+cultures of lactic bacteria able to grow at temperatures
+of 100&deg; F. to 112&deg; F. Such an organism
+was found in Bulgarian soured milk (yoghourt),
+and was considered pre-eminently adapted to
+this purpose. As has been shown in the preceding
+paragraphs, this organism is merely one of a
+large group of bacteria found distributed in the
+intestinal canal of many domestic animals, in
+manure, and in ordinary market milk. It is then
+not surprising that the introduction into the intestinal
+tract of bacteria of the type <i>Bulgaricus</i> in
+the form of tabloids has not met with any decided
+success. Although it was considered to be merely
+necessary to introduce the desired type of organism
+into the body, and the amount of lactic acid
+taken into the system by the administration of
+soured milks was looked upon as of secondary
+importance, yet, it would seem, in the light of
+recent investigations, that benefits derived from
+a soured milk regimen are attributable in part
+to a chemical as well as a purely bacterial action.
+This receives support from the fact that soured
+milk beverages prepared by the use of ordinary
+lactic bacteria, distinct from those of the <i>Bulgaricus</i>
+<span class='pagenum'><a name="Page_124" id="Page_124">124</a></span>
+type, often exert a beneficial influence
+upon human beings even although the organisms
+responsible for the fermentation are incapable
+of growth at blood temperature.</p>
+
+
+<p>It may be mentioned in conclusion that cultures
+prepared by the use of organisms of the
+type <i>Streptococcus lacticus</i> combined with <i>Bac.
+bulgaricus</i> possess a more agreeable flavour and
+aroma than those prepared from a pure culture
+of <i>Bulgaricus</i> alone.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="fig35" id="fig35"></a><img src="images/fig35.jpg" width="400" height="385" alt=
+"Bacillus bulgaricus, Showing the Cultures in English Cow's Milk"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 35</span>&mdash;<i>Bacillus bulgaricus</i>, showing the cultures in
+English cow's milk. (Magnified 450 diams.)</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="fig36" id="fig36"></a><img src="images/fig36.jpg" width="500" height="465" alt=
+"Photo-Micrograph of Pure Culture of Bacillus bulgaricus"
+title="" />
+
+<p class="cap"><span class="smcap">Fig.</span> 36&mdash;Photo-micrograph of pure culture of <i>Bacillus bulgaricus</i>.
+The administration of cultures of this organism is indicated in all
+cases of intestinal ailments, caused by the excessive growth of proteolytic
+bacteria, and consequent putrefaction of foods in the
+alimentary tract. By the formation of large quantities of lactic
+acid, a state of asepsis is ensured, which is particularly valuable
+in cases of operations on the abdomen and intestines.</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="fig37" id="fig37"></a><img src="images/fig37.jpg" width="500" height="495" alt=
+"Photo-Micrograph of Smear of Combined Culture of Bacillus bulgaricus and Bacteria paralacticus"
+title="" />
+
+<p class="cap"><span class="smcap">Fig.</span> 37.&mdash;Photo-micrograph of smear of combined culture of <i>Bacillus
+bulgaricus</i> and <i>Bacteria paralacticus</i>. This double culture possesses an advantage
+over single cultures in that, while the characteristic disinfecting
+action of the former is retained, any secondary action of the growth of this
+organism upon the milk-fat is checked by the growth of <i>Bacillus paralacticus</i>,
+thus ensuring the production of a more palatable product.</p></div>
+
+<hr />
+<p><span class='pagenum'><a name="Page_125" id="Page_125">125</a></span></p>
+
+
+
+
+<h4>CHAPTER VI</h4>
+
+<h5>THE PREPARATION OF SOURED MILK IN THE HOUSE</h5>
+
+
+<p>There is no great difficulty in making soured milk
+at home: the necessary operations are quite simple,
+but at the same time they must be conducted
+with precision and care, otherwise the results may
+be unsatisfactory and disagreeable; there may even
+sometimes be danger in badly prepared sour milk.
+It is always an advantage in such matters to
+understand the reason of things, and a few notes
+on the surrounding conditions, and what has to
+be accomplished, may be of assistance to the
+would-be experimenter.</p>
+
+<p>The majority of intelligent people are now acquainted
+with the fact that the germs of bacteria
+are to be found everywhere on the surface of the
+earth, in air, and in water, and that they are the
+sole cause of the decay of all manner of perishable
+articles.</p>
+
+<p>The distribution is unequal&mdash;bacteria are much
+<span class='pagenum'><a name="Page_126" id="Page_126">126</a></span>
+more plentiful where there is decaying matter&mdash;in
+dirty houses, sewage, or other contaminated
+water, etc. Milk is a splendid food for bacteria,
+and numerous varieties multiply in it exceedingly,
+and many of these are injurious, producing
+putrefactive changes which render the milk unwholesome,
+even poisonous in some cases. Others
+are beneficial, and are absolutely necessary for
+the souring of milk for making butter or cheese
+and for the ripening of the latter. The soured
+milk which is the subject of this book is the
+work of certain lactic-acid-producing bacteria,
+and the problem we have before us is to encourage
+the growth of the latter to the uttermost and
+to exclude the others.</p>
+
+<p>As bacterial germs are present in the air and
+readily sow themselves into any medium with
+which they come in contact, the first consideration
+is to get good fresh milk which has been as little
+exposed to the air as possible. The second is to
+conduct the experiment where the germs are
+fewest, and in cleanly surroundings, far removed
+from decaying matter and free from taints and
+smells.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="fig38" id="fig38"></a><img src="images/fig38.jpg" width="400" height="390" alt=
+"Photo-Micrograph of Smear of One-Month Culture of Bacillus bulgaricus"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 38.</span>&mdash;Photo-micrograph of smear of one-month culture
+of <i>Bacillus bulgaricus</i>. In spite of its age, the culture
+is perfectly free from any foreign organisms, which would
+otherwise lower its value for the preparation of soured
+milk, and might, indeed, make it directly injurious.<br /><br /></p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="fig39" id="fig39"></a><img src="images/fig39.jpg" width="400" height="406" alt=
+"Photo-Micrograph of Culture of Bacillus bulgaricus in Malt"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 39.</span>&mdash;Photo-micrograph of culture of <i>Bacillus
+bulgaricus</i> in malt. In cases of acute enteritis, where
+milk cannot be supported, the lactic bacilli may be
+cultivated in malt, and administered to the patient
+in this form, with occasional doses of syrup of malt,
+in order to induce a vigorous growth of the lactic
+ferments in the body.</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="fig40" id="fig40"></a>
+<img src="images/fig40.jpg" width="500" height="457" alt=
+"Photo-Micrograph of Smear from Milk that had been Allowed to Sour Spontaneously"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 40.</span>&mdash;Photo-micrograph of smear
+from milk that had been allowed to sour spontaneously.
+Ordinary market milk is always subject to infection
+from the air, milking vessels, manure, etc., and from
+these sources a mixed bacterial flora arises, with the
+result that the milk exhibits curdling, acidity, gaseous
+fermentation, or mould growth, after being stored for
+a short time. This is due to the action of sush bacilli,
+diplococci, yeasts, and moulds as are shown in this
+illustration.</p></div>
+
+<p>However fresh the milk may be, it will contain
+useless or injurious bacteria, and we must
+<span class='pagenum'><a name="Page_127" id="Page_127">127</a></span>get rid of these before attempting to introduce
+those whose growth we wish to encourage. This
+is effected by heat. All the living bacteria and
+most of the germs are killed at temperatures
+somewhat under the boiling point. Having sterilised
+the milk in this way, it is necessary, as far
+as possible, to prevent the entrance of fresh germs
+from the atmosphere, and we therefore let the milk
+cool down in covered dishes. When the temperature
+descends to about 100&deg; F. the culture of the
+special bacteria is introduced, the covers are
+replaced, and the milk vessels maintained at or
+near this temperature for twelve hours, when the
+soured milk is ready for use. It is not necessary
+to use fresh culture every time&mdash;a little of the
+soured milk will take its place, and this may be
+repeated as many as fourteen times before it is
+necessary to start off again with a fresh culture.
+A great deal depends on the care exercised and
+the freedom of the surroundings from bacterial
+germs. Under the best conditions wild germs
+will gradually accumulate in the soured milk,
+but their increase may be greatly delayed by
+attention to the precautions mentioned. The
+ordinary souring of milk for butter and cheese
+making is conducted in cool surroundings, as
+<span class='pagenum'><a name="Page_128" id="Page_128">128</a></span>
+already stated, because in such conditions the
+lactic-acid-producing germs increase relatively
+faster than the wild germs, and so gain the upper
+hand, but in the case of our special soured milk
+we kill out, practically, all wild bacteria and
+germs, and the pure culture having the field to
+itself, we can conduct the operation at a higher
+temperature where the action of the bacteria
+is at its maximum, and so obtain the necessary
+lactification in the minimum of time.</p>
+
+
+<p>The appliances for the souring of milk on the
+domestic scale require some consideration. We
+propose to describe the principal forms of apparatus
+which have been put on the market for the
+purpose, and then to give such suggestions as
+may assist the ingenious in making apparatus for
+themselves. Those who wish for information on
+the subject of larger apparatus will find it in the
+following chapter.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig41" id="fig41"></a>
+<img src="images/fig41.jpg" width="500" height="474" alt=
+"Photograph of Agar Culture, Inoculated with a Lactic Powder"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 41</span>&mdash;Photograph of Agar Culture, inoculated with a lactic
+powder offered to consumers under a fancy name. Working on the
+assumption that the presence of lactic bacteria is inimical to the
+growth of septic organisms, this preparation has been placed on
+the market.<br /><br />
+
+The plate shows, however an abundance of colonies of foreign
+organisms&mdash;sporogenous bacilli, <i>Staphylococcus pyogenes albus</i>, and
+<i>Staphylococcus pyogenes aureus</i>. These organisms are shown in the
+appended photo-micrographs, and constitute impurities in the
+preparation.</p></div>
+
+<table width="100%" summary="Spore forming bacillus" border="0">
+<tr>
+<td class="m50">
+<div class="figcenter" style="width: 200px;">
+<img src="images/fig41a.jpg" width="200" height="184" alt=
+"Spore forming bacillus"
+title="" />
+
+<p class="caption">Spore forming bacillus</p></div></td>
+<td class="m50">
+<div class="figcenter" style="width: 200px;">
+<img src="images/fig41b.jpg" width="200" height="178" alt=
+"Staphylococcus pyogenes albusr"
+title="" />
+
+<p class="caption"><i>Staphylococcus pyogenes albus</i></p></div></td>
+</tr>
+</table>
+
+<div class="figcenter" style="width: 400px;"><a name="fig42" id="fig42"></a>
+<img src="images/fig42.jpg" width="400" height="475" alt=
+"Photograph of Test-Tubes of Sterile Milk, Inoculated with a Tablet Preparation Said to Contain Pure Cultures"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 42</span>&mdash;Photograph of Test Tubes of Sterile Milk,
+inoculated with a tablet preparation said to contain pure
+cultures. The darker liquefied portion of the tube-contents
+is due to digestion of the curd by proteolytic bacteria, thus
+indicating impure culture. Pure cultures of lactic acid
+bacteria coagulate the milk uniformly, but do not produce
+any subsequent change in the appearance of the culture,
+even after several months.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="fig43" id="fig43"></a>
+<img src="images/fig43.jpg" width="400" height="485" alt=
+"Photograph of Test-Tubes of Sterile Milk, Each Tube having been Inoculated with a Tablet of a Preparation Said to Contain Pure Cultures"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 43</span>&mdash;
+Photograph of Test Tubes of Sterile Milk,
+each tube having been inoculated with a tablet of a preparation
+said to contain pure cultures. Here, again,
+there is evident peptonisation of the curd, thus indicating
+infection by proteolytic ferments. Cultures from
+these tubes demonstrated the presence of a foreign
+organism. Microscopical examination failed to disclose
+the presence of <i>Basillus Bulgaricus</i>.</p></div>
+
+<div class="figcenter" style="width: 400px;"><a name="fig44" id="fig44"></a>
+<img src="images/fig44.jpg" width="400" height="461" alt=
+"Photograph of Test-Tubes of Sterile Milk Inoculated with a Tablet of 'Lactobacilline'"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 44</span>&mdash;Photograph of Test Tubes of Sterile Milk, inoculated
+with a tablet of "Lactobacilline." In contra-distinction
+to those shown in Figs. 42 and 43, these tubes
+exhibit homogeneous curdling of the milk without any
+subsequent digestion or peptonisation of the coagulum.
+This is indicative of the purity of the culture.</p></div>
+
+<p>The Society "Le Ferment" of Paris, which
+has been authorised by Professor Metchnikoff
+to prepare and supply to the public his sour milk
+culture, provides an apparatus for the treatment
+of the milk. It is shown in Fig. 45, which consists
+of a double box having the intervening space
+packed with a non-conducting material. It is
+<span class='pagenum'><a name="Page_129" id="Page_129">129</a></span>provided with a tight lid. Inside, there is accommodation
+for two milk vessels, each with a capacity
+of about two thirds of a pint. The most
+difficult thing in the souring of milk is to maintain
+the temperature as nearly at 100&deg; F. as possible
+while the culture is in action. This result is
+attained by filling the vessel in the middle with
+boiling water. The insulated walls hinder the
+escape of heat, and the quantity of boiling water
+used is calculated to maintain the temperature
+steady for the twelve hours of cultivation; but
+in cold, frosty weather it is necessary to refill
+the central vessel with boiling water in the middle
+of the period.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig45" id="fig45"></a>
+<img src="images/fig45.jpg" width="500" height="218" alt=
+"Apparatus of 'Le Ferment' Co."
+title="" />
+
+<p class="caption"><span class="smcap">Fig. 45</span></p></div>
+
+<p>The milk jars are washed with hot boiled water
+and turned upside down to dry. They should
+not be wiped with a cloth. Boil the milk to be
+<span class='pagenum'><a name="Page_130" id="Page_130">130</a></span>
+treated for ten minutes, stirring it to promote
+evaporation, as it is advantageous to have it in
+concentrated form. Cool rapidly to 100&deg; F. by
+placing the boiling vessel in cold water, add to
+each bowl one third of a tube of the culture in
+powder form, fill up with the boiled and cooled
+milk, stir well and cover. Place the jars in the
+box and fill the central vessel with boiling water,
+shut the lid tight, and do not open it (unless
+a fresh charge of boiling water is needed) for ten
+or twelve hours, when it will be ready for use.
+If the liquid culture is used (one small phial for
+each bowl) the milk should be cooled to 86&deg; F.
+instead of 100&deg; F., as with the powder. The
+culture is also supplied in tabloid form. The
+powder and tabloids keep well, but the liquid can
+only be relied on for about two months. The
+milk prepared as above should be stored in a cool
+place, the lids being kept on the bowls. It is
+good for about two days, after which it becomes
+too sour. It can be eaten with sugar, which
+not only sweetens it but is beneficial in affording
+additional suitable food for the acid-producing
+bacilli. If fresh milk cannot be had, condensed,
+sterilised, or pasteurised milk may be used, but,
+of course, fresh milk is best. Condensed milk
+<span class='pagenum'><a name="Page_131" id="Page_131">131</a></span>should be diluted with two parts of boiling water
+and then treated like ordinary milk.</p>
+
+<p>An apparatus on similar principles is sold by
+the Maya Bulgare Company, Ltd., and is illustrated
+in Fig. 46.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="fig46" id="fig46"></a>
+<img src="images/fig46.jpg" width="400" height="450" alt=
+"Soured Milk Apparatus of the Maya Bulgare Company, Limited"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 46</span>&mdash;Soured Milk Apparatus of the Maya Bulgare
+Company, Limited, consisting of an insulated box, hot-water
+vessel, and covered vessels containing the milk and culture.
+The apparatus consists of cabinet in deal, Maya Bulgare
+ferment in 20-dose bottles, Maya Bulgare ferment in 100-dose
+bottles, compressed Maya Bulgare tablets in boxes of 8 tubes,
+Maya Bulgare caramels in boxes of 40, reduced milk, china
+funnels, and thermometers.</p></div>
+
+
+<p>The box is insulated, but the door is on the side,
+the hot water vessel is underneath, and the covered
+vessels containing the milk and culture are
+placed on a shelf above. In the front of the
+illustration are shown the various packages in which
+the liquid and powder cultures are put up. The
+procedure is exactly the same as with "Le Ferment"
+apparatus.</p>
+
+
+<p>Lactic Ferments, Limited, make use of a different
+principle to maintain the temperature steady
+during the lactifying period.
+Their apparatus (Fig. 47) consists
+
+<span class="figright" style="width: 200px;"><a name="fig47" id="fig47"></a>
+<img src="images/fig47.jpg" width="200" height="238" alt=
+"Soured Milk Apparatus of the Maya Bulgare Company, Limited"
+title="" />
+
+<span class="caption"><span class="smcap">Fig. 47</span></span></span>
+
+of a water vessel mounted
+on a stand. The milk vessels
+(tumblers) are placed in the
+water, and the temperature
+maintained at the proper figure
+by a small night light burning
+underneath. It is recommended
+that the milk should be placed in an earthenware
+jar or jug, which is stood in a pot of water kept
+<span class='pagenum'><a name="Page_132" id="Page_132">132</a></span>
+boiling for an hour. After cooling add from three
+to six previously crushed tabloids of culture, and
+stir well with a glass rod which has been sterilised
+in boiling water. The milk is then transferred to
+three tumblers, which it should fill, and these are
+put into the water vessel, the water in which
+should be at about 100&deg; F., and the night light
+started.</p>
+
+
+<p>Messrs. Allen &amp; Hanbury, Limited, also make
+use of the night light to maintain the proper
+temperature during incubation in their "Sauerin"
+apparatus (Fig. 48).</p>
+
+<p>No water, however, is placed in the metal
+container. The procedure is the same as that
+already described, and both tablet and liquid
+pure cultures are supplied. For children it is
+recommended that the incubation should occupy
+from three to four hours only, in other cases eight
+to ten hours. Grated nutmeg, ground cinnamon,
+or other flavouring, and cream may be used
+with the soured milk.</p>
+
+<p>The night light is also employed in the "Veronelle"
+apparatus of Messrs. Clay, Paget and
+Company, Limited (Fig. 49).</p>
+
+<table width="100%" summary="Soured Milk Apparatus">
+<tr>
+<td class="m50b">
+<div class="figcenter" style="width: 200px;"><a name="fig48" id="fig48"></a>
+<img src="images/fig48.jpg" width="200" height="215" alt=
+"Messrs. Allen &amp; Hanbury's Soured Milk Apparatus"
+title="" /></div></td>
+<td class="m50">
+<div class="figcenter" style="width: 200px;"><a name="fig49" id="fig49"></a>
+<img src="images/fig49.jpg" width="200" height="377" alt=
+"Vironelle Apparatus for Souring Milk, Made by Messrs. Clay, Paget &amp; Company, Limited"
+title="" /></div></td>
+</tr><tr>
+<td class="m50">
+<p><span class="smcap">Fig. 48.</span>&mdash;Messrs. Allen &amp; Hanbury's
+Soured Milk Apparatus.
+They maintain the temperature by
+means of a night light, and the culture
+they use they call "Sauerin."</p></td>
+<td class="m50">
+<p><span class="smcap">Fig. 49.</span>&mdash;Vironelle Apparatus
+for souring milk, made by
+Messrs. Clay, Paget &amp; Company,
+Limited. The milk in this case
+is placed in an earthenware jar,
+and is sterilised by placing in a
+saucepan of water and boiling
+it. The culture is added after
+cooling, the period of incubation
+being about six hours.</p>
+</td></tr>
+</table>
+
+<p>The containing vessel is of tin or aluminium,
+and has two stands, the high one for hot and
+<span class='pagenum'><a name="Page_133" id="Page_133">133</a></span>the low one for cold weather, as in the latter case
+greater heat is needed to maintain the incubating
+temperature. The milk is placed in an earthenware
+jar and is sterilised by placing it in a saucepan
+of water and boiling it; continuing the boiling
+for half an hour. It is allowed to cool to about
+98&deg; F., and placed in the incubator, culture added,
+and the lamp lighted, the cover of the incubator
+being kept on. The period of incubation is given
+as six hours. To prepare the next day's supply a
+tablespoonful of the soured milk is retained and
+used instead of the culture. This may be continued
+for fourteen days, when a fresh start
+with culture is necessary. The soured milk will
+keep for thirty-six hours. Capacity, one and one
+half and two pints; also a large size for family use.</p>
+
+<p>For the preparation of soured milk on a small
+scale, one of the various forms of vacuum flasks
+now on the market may be used with satisfactory
+results. A little cold water must be poured
+into the flasks, and warm water added, until,
+by means of three to four changes, boiling water
+can be safely poured in without cracking the
+flask.</p>
+
+
+<p>This boiling water must be allowed to remain
+in for about twenty minutes, and then replaced
+<span class='pagenum'><a name="Page_134" id="Page_134">134</a></span>
+by freshly boiled milk that has been cooled, so
+that its temperature in the flask is about 105&deg; F.
+The culture of lactic organisms should then be
+added, the opening of the flask plugged with clean
+cotton-wool, and the cap screwed on.</p>
+
+<p>In an actual test, the temperature of the milk
+placed in such a flask was 105&deg; F., at 7.30 <span class="smcap">P.M.</span>,
+and had dropped to 93&deg; F. by 9 <span class="smcap">A.M.</span>, the following
+day. The milk was curdled, and possessed
+the normal acid taste of such cultures.</p>
+
+<p>The different types of apparatus are all quite
+simple, and it would be easy to make something
+at home. Get two round tins, the one less in
+diameter by from two to three inches than the
+other, put one or two pieces of wood across the
+bottom inside the larger tin, and fill up the space
+between with cotton-wool, which is an excellent
+non-conductor of heat. Place the smaller tin
+centrally inside the larger one. Fix three or four
+distance pieces of wood in the space between them,
+fill up with cotton-wool, leaving a little space at
+the top to permit the lid of the smaller tin to be
+fixed on. The boiling-water vessel may be a tin
+saucepan with a lid, but no handle, and its proper
+place would be on the bottom of the inner tin.
+A tripod stand made of three pieces of wire bound
+<span class='pagenum'><a name="Page_135" id="Page_135">135</a></span>
+together, and with legs reaching past the hot-water
+vessel to the bottom of the tin, would support
+a false bottom of tin forming the shelf on
+which the vessels of milk to be treated would
+rest. These might be tumblers covered with
+tin lids. To prevent radiation through the lid
+of the inner tin, a thick pad or hood of
+cotton-wool packed between cloth would be
+placed over the top. A little experimenting
+would be necessary to determine the quantity
+of boiling water required to maintain the proper
+temperature.</p>
+
+<p>The soured milk obtained in the above manner
+is of the consistency of ordinary buttermilk; a
+separation of whey frequently takes place, and
+this may be poured off if desired. The taste
+and flavour should be pleasantly acid and agreeable,
+and both are distinctive enough to give a
+good idea of the purity of the product. In many
+places a more concentrated article is made by
+boiling down the milk to one half or one third
+of its bulk, and then fermenting it in the ordinary
+way. A kind of thick pudding is thus obtained,
+which is highly recommended both as an agreeable
+article of food and as a stronger medium for the
+support of the germs it is the purpose of the
+<span class='pagenum'><a name="Page_136" id="Page_136">136</a></span>
+sour milk treatment to introduce into the digestive
+system.</p>
+
+<p>The cultures for making soured milk can now
+be had from all the leading wholesale and retail
+chemists, with directions as to the quantities to
+be used.</p>
+
+<p>It is very necessary that the milk used should
+be not only fresh and good, but also free from
+chemical preservatives. The effect of these is to
+inhibit the growth and development of bacteria,
+and they have therefore an injurious influence
+on the special lactifying germs it is our object
+to cultivate. Preservatives are now not nearly
+so much used as they were, a few years ago, and
+there should be no difficulty in obtaining milk
+free from them.</p>
+
+<p>For keeping both fresh and soured milk good
+a small ice-chest is an excellent device. The
+germs which are continually dropping into milk
+kept in open vessels in the air, even in cleanly
+surroundings, are mostly kept out in the close
+ice-chest, and the low temperature prevents in
+a natural way the development of the bacterial
+germs already in the milk. For the preservation
+of all kinds of foods the ice-chest is a capital
+investment, not to mention the benefit of having
+<span class='pagenum'><a name="Page_137" id="Page_137">137</a></span>
+cooled drinks, etc., as required. They manage
+things well in this respect in the United States,
+where ice is regarded as a necessity in the summer
+time by even the poorest people, and is delivered
+with the same regularity as the milk.</p>
+
+<p>It is necessary to utter a word of warning as to
+certain forms in which the sour milk bacillus is
+being offered to the public. It is being compounded
+with sugar, chocolate, and other articles,
+and sold in the form of sweets, etc. There
+is no reliable proof that these preparations are
+valuable. Certainly, sugar is a medium in which
+the lactifying germs can live, but the quantity
+so introduced into the system must be very small
+compared with what is obtained from properly
+fermented milk. It takes some time, even with
+strong cultures, to fix the acid-producing germs
+in the large bowel where they are wanted, and
+until proper evidence is forthcoming that confectionery
+preparations are efficacious we would
+recommend that only the regularly fermented
+milk be used. It would save trouble, no doubt,
+to treat oneself with a few chocolate creams containing
+the necessary germs daily, but if the matter
+is taken up seriously it will be better to take
+some pains and stick to methods the efficacy of
+<span class='pagenum'><a name="Page_138" id="Page_138">138</a></span>
+which has been demonstrated, leaving the others
+until their <i>bona fides</i> has been proved. There
+are always enterprising firms who are prepared
+to simplify things for us, but we must make
+sure that their simplifications are warranted.</p>
+
+<hr />
+
+<p><span class='pagenum'><a name="Page_139" id="Page_139">139</a></span></p>
+
+<h4>CHAPTER VII</h4>
+
+<h5>THE PREPARATION OF SOURED MILK IN THE DAIRY</h5>
+
+
+<p>There is a tendency in certain medical quarters
+to discourage the use of soured milk "made for
+profit." This view leaves out of account the fact
+that besides being of value in medicine, the article
+in question is also an excellent food, which, as we
+have seen, has been consumed by multitudes of
+people for ages in many parts of the world. There
+seems also to be satisfactory evidence that a larger
+percentage than usual of the people who make
+soured milk a staple of diet attain to a ripe old
+age. How does it become such a dangerous
+thing the moment the doctors get it into their
+hands? Of course if a man has an acute disease
+he places himself entirely in the hands of his
+medical man, and eats what is prescribed for
+him, or at least he ought to do so, and if he makes
+such a submission he is entitled at least to the
+comfort of being able to feel that his doctor is free
+<span class='pagenum'><a name="Page_140" id="Page_140">140</a></span>
+from unreasonable prejudices. For the implication
+that an article "made for profit" is naturally
+suspect casts an unwarranted stigma on a large
+number of honourable people. There are dishonest
+tradesmen just as there are dishonest and
+careless doctors, but to saddle a whole class with
+the offences of a few would not be a justifiable
+proceeding in either case. Besides, it is not to
+the interest of the manufacturing chemist or the
+dairyman to turn out spurious cultures or bad
+soured milk, and on the whole we see no reason
+why they should not engage in the business.</p>
+
+<p>The widespread use of soured milk in other
+countries as a regular article of diet seems to
+indicate that all manner of people, except those
+suffering from diseases which necessitate medical
+regulation of diet, might with probable benefit to
+themselves add this article to their food list;
+and it looks as if a good many of them intend doing
+so, even if scandalised doctors threaten "to abandon
+the cure."</p>
+
+<p>The dairyman who knows his business does
+not need to be told of the care which is necessary
+to keep milk in good condition. The merely
+commercial consideration of avoiding loss has made
+him ready to inquire into the best means of prolonging
+<span class='pagenum'><a name="Page_141" id="Page_141">141</a></span>
+the life of milk as a merchantable article.
+For a time he relied on chemical preservatives,
+but their day is now almost over, and filtration,
+pasteurisation, and cold storage have taken their
+place. Any one conversant with the trade knows
+how widely these methods have been adopted of
+late years; we may, therefore, assume that the
+average dairyman has at his command milk
+suitable for the incubation process.</p>
+
+
+
+<p>The demand for soured milk is not as yet a
+very large one, and the apparatus so far developed
+for its production is meant for the treatment of
+small quantities. After describing the principal
+appliances at present in the market we propose
+to make some suggestions as to the construction
+of larger apparatus.</p>
+
+<p>A firm which has given great attention to the
+question of maintaining fixed temperatures is
+that of Messrs. Charles Hearson &amp; Co., Ltd.
+Their incubators for chicken hatching are known
+all over the world; and their appliances for biological
+incubation are very generally used in bacteriological
+laboratories. With such experience
+it was natural that they should turn their attention
+to soured milk apparatus, and the result
+is the "Lactobator" (Figs. 50 and 51).</p>
+
+<div class="figcenter" style="width: 400px;"><a name="fig50" id="fig50"></a>
+<img src="images/fig50.jpg" width="400" height="528" alt=
+"'Lactobator' Made by Messrs. Charles Hearson &amp; Co., Limited"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 50.</span>&mdash;"Lactobator" made by Messrs. Charles
+Hearson &amp; Co., Limited, which is used for the incubation
+of pure culture in milk in a fairly large way.
+The illustration shows the "Lactobator" closed.</p></div>
+
+<div class="figcenter" style="width: 500px;"><a name="fig51" id="fig51"></a>
+<img src="images/fig51.jpg" width="500" height="584" alt=
+"Messrs. Hearson &amp; Company's 'Lactobator'"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 51.</span>&mdash;Messrs. Hearson &amp; Company's "Lactobator," showing
+the internal arrangements.</p></div>
+
+<p><span class='pagenum'><a name="Page_142" id="Page_142">142</a></span>
+A copper vessel made to contain water has
+placed in it a stoneware jar which holds two
+gallons of milk; on the top is a lid which carries a
+thermometer for indicating the temperature of
+the milk. Heat is supplied by a gas ring under
+the copper vessel; and in the gas supply is the
+patent thermostat made use of by Messrs. Hearson
+also in their biological and poultry incubators,
+in which a capsule containing a liquid arranged
+to boil at a certain predetermined temperature
+is the regulating factor. When the liquid boils,
+the capsule expands, and by certain mechanical
+devices regulates the gas supply so as to produce
+exactly the temperature required.</p>
+
+<p>The procedure is as follows: The jar is filled
+with milk, and water is run into the copper vessel
+by the funnel until it runs over at the overflow
+pipe. The thermostat is lifted off and the full
+gas supply allowed to pass to the burner, the
+temperature of the milk brought up to 180&deg; F.
+and maintained for half an hour at this figure.
+The gas is then turned off, and cold water run
+through the funnel until the temperature of the
+milk registers 95&deg; F. The culture is added, the
+lid replaced, and the thermostat put into the pocket
+at the side of the vessel; the gas relighted, and
+<span class='pagenum'><a name="Page_143" id="Page_143">143</a></span>when the temperature reaches 100&deg; to 106&deg; F.
+the capsule of the thermostat will expand and
+close the gas to a peep, which is just sufficient to
+maintain the temperature within the above limits.
+After eight hours the incubation is completed.</p>
+
+
+<p>Edgar's patent apparatus, the "Lactogenerator,"
+as provided by the Dairy Supply Co., Ltd.,
+is shown in Fig. 52.</p>
+
+<div class="figright" style="width: 150px;"><a name="fig52" id="fig52"></a>
+<img src="images/fig52.jpg" width="150" height="235" alt=
+"Edgar's 'Lactogenerator,' Sold by the Dairy Supply Co., Limited"
+title="" />
+
+<p class="caption"><span class="smcap">Fig. 52.</span> Edgar's
+"Lactogenerator"</p></div>
+
+<p>The milk is placed in a tinned copper-jacketed
+vessel and water run in through a vertical pipe
+until it runs off at the overflow.
+Two gas connections are required
+with cocks on each, the one to
+heat up the milk to the boiling
+point and maintain it at this for
+thirty minutes. A skimmer which
+has been placed in the milk lifts
+out the coagulated protein and
+albumen which rise to the top.
+The cock is then shut and cold
+water run through the jacket till the thermometer
+shows 90&deg; F., when the culture is added, and the
+other gas supply with the regulator turned on,
+and the temperature is automatically maintained
+at about 90&deg; F. Time of incubation eight to nine
+hours. It is recommended to turn cold water
+<span class='pagenum'><a name="Page_144" id="Page_144">144</a></span>
+into the jacket at the end of the period to prevent
+overincubation.</p>
+
+<p>A somewhat similar apparatus is that of the
+Willows Refrigerating Co., Ltd. (Fig. 53), with
+the exception that it has no automatic heat regulator.
+It is made of tinned steel, and the operations
+are the same, but the sterilising temperature
+(obtained by a gas ring or hot plate) is given as
+180&deg;, and the incubating temperature 100&deg; to
+104&deg; F. for a period of twelve hours. Presumably
+this temperature is maintained by a small gas
+jet or other similar source of heat. The capacity
+is two gallons.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="fig53" id="fig53"></a>
+<img src="images/fig53.jpg" width="400" height="295" alt=
+"Apparatus of the Willows Refrigerating Co., Limited"
+title="" />
+
+<p class="caption"><span class="smcap">Fig. 53</span>
+Apparatus of the Willows Refrigerating Co., Ltd.</p></div>
+
+<p>In the apparatus hitherto described the milk
+is sterilised in bulk, and is filled into bottles or
+<span class='pagenum'><a name="Page_145" id="Page_145">145</a></span>
+jars after incubation, which is not a desirable
+thing to do, unless the soured milk is for immediate
+consumption, as there is likely to be contamination
+with injurious germs from the atmosphere. In
+the domestic apparatus the milk is usually incubated
+in covered jars in which it can be kept
+until required for use, and the practice on the
+larger scale should be the same.</p>
+
+<p>The Dairy Outfit Co., Ltd., have recognised
+this in their "Lacto" apparatus
+(Fig. 54).</p>
+
+<div class="figright" style="width: 200px;"><a name="fig54" id="fig54"></a>
+<img src="images/fig54.jpg" width="200" height="355" alt=
+"'Lacto' Apparatus of the Dairy Outfit Co., Limited"
+title="" />
+
+<p class="caption"><span class="smcap">Fig. 54</span><br />
+"Lacto" Apparatus of the
+Dairy Outfit Co., Ltd.</p></div>
+
+<p>A cylindrical vessel is set
+loosely on a stand, beneath
+which is a lamp calculated
+to maintain the incubating
+temperature. The milk is
+placed in bottles with metal
+screw tops, and these are
+put into the cylindrical vessel;
+water is run in round
+them through the side funnel,
+the vessel lifted off the stand,
+and heated to sterilising point
+on a stove. Cold water is
+then run in through the
+funnel until the temperature is low enough for
+<span class='pagenum'><a name="Page_146" id="Page_146">146</a></span>
+incubation. Culture is added to each bottle
+and the lids screwed on, the vessel lifted
+on to its stand, and the lamp lighted. The
+cover of the apparatus has a thermometer fixed
+on it.</p>
+
+<p>On the large scale the treatment of the milk
+would take place entirely in the jars in which it
+would be sent out, and the sterilisation and incubation
+would be conducted in different pieces
+of apparatus. The sterilisation would be effected
+either (1) by direct steaming, or (2) by hot water
+heated by steam. Fig. 55 shows the first type
+of sterilisation. The tank is of wrought iron or
+steel with strengthening pieces of angle iron.
+The door, with pulleys and counterweight for
+easy handling, is fastened steam-tight by hinged
+bolts. The apparatus is mounted on a stand at
+a convenient height for handling the bottles; and
+in front is another stand with channel iron rails
+to take the waggon in which the bottles or jars
+to be sterilised are packed. When the door is
+fast, steam is turned on, and regulated to produce
+the proper temperature by the thermometer
+fixed in the shell, in which a pressure gauge is
+also secured. After sterilising, the door is opened
+and the waggon drawn forward to the outside,
+<span class='pagenum'><a name="Page_147" id="Page_147">147</a></span>allowed to cool, or removed elsewhere to cool,
+and allow space for a new charge.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig55" id="fig55"></a>
+<img src="images/fig55.jpg" width="500" height="460" alt=
+"Sterilising Apparatus for Sterilising Milk On the Large Scale"
+title="" />
+
+<p class="cap"><span class="smcap">Fig. 55.</span>&mdash;Sterilising Apparatus for sterilising milk on the large
+scale. The bottles of milk are sterilised, and the culture can then
+be added, and the incubation allowed to proceed in an insulated
+chamber.</p></div>
+
+
+<p>The second method of sterilising is by hot
+water, as in Fig. 56. The bottles or jars are placed
+on a perforated false bottom in the rectangular
+tank, water run in up to the necks, and steam
+turned on; the lid is fastened with hinged and
+hooked bolts; a thermometer fastened in the lid,
+and with a long stem enclosed in metal, indicates
+the temperature. At the end of the sterilising
+process cold water is turned on, and at the same
+time the overflow water cock is opened; the
+cold water gradually reduces the temperature,
+and the incubating point is quickly reached.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="fig56" id="fig56"></a>
+<img src="images/fig56.jpg" width="400" height="444" alt=
+"Another Method of Sterilising (Dairy Supply Co., Ltd.). An American Apparatus for Preparing Soured Milk"
+title="" />
+
+<p class="caption"><span class="smcap">Fig. 56</span><br />
+Another Method of Sterilising (Dairy Supply Co., Ltd.).</p></div>
+
+
+<p>Incubation in bottles or jars, sterilised in these
+ways, can best be conducted in an insulated room,
+with say, six inches of silicate cotton, granulated
+cork, or washed cow hair packed between two-inch
+by six-inch battens, covered with matching
+on either side, and lined with sheet zinc. It
+would be an advantage to have an air-lock or
+anteroom into which the waggons or trays of
+sterilised jars could be run, and the door of the
+anteroom closed before the door of the insulated
+room is opened. This would tend to prevent
+variations of temperature in the room, and also,
+<span class='pagenum'><a name="Page_148" id="Page_148">148</a></span>
+by checking free communication with the outside
+air, decrease contamination. The waggons
+of jars would be run in, and culture added
+to each jar by a sterilised pipette. The atmosphere
+of the room would be kept pure by running
+in air frequently through a filter of moist cotton-wool
+by means of an electric fan, and at intervals
+the interior would be sterilised by the use of
+formalin vapour.</p>
+
+
+<p><span class='pagenum'><a name="Page_149" id="Page_149">149</a></span></p>
+
+<p class="caption"><i>Details of an American Apparatus for Preparing Soured Milk</i></p>
+
+<div class="figcenter" style="width: 500px;"><a name="fig57" id="fig57"></a>
+<img src="images/fig57.jpg" width="500" height="707" alt=
+"An American Apparatus for Preparing Soured Milk"
+title="" />
+
+
+<p class="caption"><span class="smcap">Fig. 57</span></p>
+
+<p class="cap">The figures give diagrams A, B,
+C, and D of an apparatus useful
+for the preparation of lactic foods.
+The incubating can A, is made of
+block tin, and is intended to contain
+the milk. B, the warm water
+container, should be a stout walled
+vessel with a circular aperture in
+the lid, through which the incubating
+can may be passed, and
+clamped down as in C.<br /><br />
+
+B is fitted with three stout iron
+legs, which should be sufficiently long to allow of a small lamp or gas-jet
+being placed beneath the container to maintain a uniform temperature.<br /><br />
+
+D gives an external view of the apparatus.<br /><br />
+
+For the preparation of soured milk, separated milk is placed in the
+incubating can, and heated up to 100&deg; C. (212&deg; F.) for thirty minutes.
+It is then allowed to cool to room temperature, and the culture, or tablet
+containing the lactic acid bacteria, is then added, and thoroughly
+stirred for a minute or so. The can is then immersed in the warm
+water container and kept at a temperature of 86&deg; F. to 104&deg; F., according
+to the organisms used, for ten to twelve hours. By the end of this
+time the milk ought to be converted to a jelly-like mass, and after
+being stirred vigorously for a short time, may be cooled on ice, and is
+then ready for consumption.</p></div>
+
+<p><span class='pagenum'><a name="Page_150" id="Page_150">150</a></span></p>
+
+<p>The incubating temperature could very conveniently
+be maintained by an electric radiator,
+and as the insulation would largely prevent
+leakage, the amount of electric current used would
+not be large. The regulating apparatus might
+consist of a thermometer with platinum wires
+fused through the stem at the proper temperature,
+say 100&deg; F. When the mercury rises to this
+figure it will complete the circuit of a battery
+which will actuate certain well-known devices
+for turning off the current which actuates the
+radiator. In this way a very fine automatic
+arrangement would be achieved. Steam pipes
+might be used instead of the radiator, and the
+thermometer above described could be used in
+this case also, with appliances to cut off the steam.</p>
+
+<p>On the large scale, labour-saving appliances,
+such as the mechanical brush jar and bottle
+washer, and the automatic filler for jars or bottles,
+would be employed, and an overhead trackway for
+carrying the trays of jars from the steriliser to the
+incubator would be a great convenience. A
+further adjunct of considerable importance would
+be a cold room, worked either by ice or a refrigerating
+machine, in which the jars could be stored
+after incubation, so as to arrest the process of
+lactification, and maintain the soured milk in
+good condition until required for use.</p>
+
+<hr />
+
+<p><span class='pagenum'><a name="Page_151" id="Page_151">151</a></span></p>
+
+<h4>CHAPTER VIII</h4>
+
+<h5>SOURED MILK IN HEALTH AND DISEASE</h5>
+
+
+<p>When people are ill the best thing they can do
+is to place themselves in the hands of the doctor,
+who will try to regulate their lives, including their
+diet, in accordance with the conditions which
+science suggests as the most likely to lead to their
+recovery.</p>
+
+<p>It is not the aim of this book to teach persons
+who should be under medical treatment to doctor
+themselves; soured milk may or may not be
+beneficial in their case&mdash;that is for the medical
+man to say; and further, if it should be beneficial
+the doctor ought to have its preparation
+under his control. Slight differences in quality
+and purity may count for much in cases of acute
+disease, differences which might not matter to
+the person who requires no medical attention,
+and who consumes the article as a health-giving
+food. A considerable body of evidence is already
+<span class='pagenum'><a name="Page_152" id="Page_152">152</a></span>
+on record as to the potency in certain cases of
+soured milk as a curative agent, and it seems to
+have taken its place in medicine as a recognised
+remedy.</p>
+
+<p>There is a wide field of usefulness, however,
+outside of the strictly medical one. Professor
+Metchnikoff has collected many striking examples
+of individuals and peoples inhabiting different
+parts of the world, who thrive, and in many cases
+attain to a great age, and whose diet consists
+largely of soured milk. He has made a wide and
+general inquiry into the causes which tend to
+shorten life, and makes out a strong case in support
+of the view that in many cases this is the
+result of what is called auto-intoxication or self-poisoning.
+In man and in the mammalia generally,
+the colon or large intestine is very largely
+developed; this organ is not of much value in the
+digestion of food, and seems to be chiefly a receptacle
+for waste material; it is, as a rule, extremely
+rich in bacterial flora, which produce putrefactive
+changes in the waste material. As a result
+various poisonous principles are evolved, and these
+find their way into the blood, accompanied frequently,
+there is every reason to believe, by the
+injurious bacteria themselves. In this way many
+<span class='pagenum'><a name="Page_153" id="Page_153">153</a></span>
+diseases and ailments are produced which shorten
+life. The inquiry then naturally turns to what
+is the best way of dealing with this state of matters.
+It is known that the bacteria referred to
+flourish best in alkaline or at least non-acid surroundings,
+and it is known that these conditions
+very frequently exist in the large intestine. Acids
+are the best antiseptics; they have been used from
+time immemorial as preservatives; pickles are
+preserved in vinegar or acetic acid, and when
+milk is allowed to sour under proper conditions,
+the germs of putrefaction are destroyed or their
+activity inhibited, and it keeps a considerable
+time. Doubtless, in hot countries, it was this
+property of lactic acid which first led to milk being
+artificially soured with a view to its preservation
+as an article of food. So powerful is lactic acid
+in this respect that it is a custom in some countries
+to preserve meat by placing it in soured milk.</p>
+
+<p>How can acids be applied so as to control the
+bacterial flora of the large intestine? Not in the
+ordinary way, because, when administered through
+the mouth, they are used up long before they can
+penetrate to the colon. The brilliant idea occurred
+to Professor Metchnikoff, of administering acid-producing
+germs which might work their way
+<span class='pagenum'><a name="Page_154" id="Page_154">154</a></span>
+through the digestive system, and, reaching the
+large intestine, produce the acid required. After
+much experimenting the bacillus of Massol, <i>Bacillus
+bulgaricus</i>, was adopted as the most suitable.
+The Bulgarian bacillus is an extremely vigorous
+one, multiplying with great rapidity, and persisting
+in conditions that would be inimical to
+other microbes. The growth and development
+of bacteria is interfered with by the products of
+their own activity; thus, ordinary lactic-acid-producing
+organisms die when a certain amount
+of lactic acid has been developed; the same fate
+overtakes the Bulgarian bacillus, but it survives
+longer and is able to produce as much as two and
+one half per cent. of lactic acid in milk before it
+ceases operations. It seemed therefore the most
+likely to be able to survive the journey through
+the digestive system. Experiments fully bore out
+this supposition, as no great difficulty was encountered
+in naturalising the Bulgarian bacillus
+in the large intestine, not only in milk cultures,
+but grown in solution of malt, bouillon, etc. It
+thrives in all kinds of sugar, and therefore can be
+administered in a variety of media, very beneficial
+results following in many cases. Direct tests
+showed a large reduction of the injurious intestinal
+<span class='pagenum'><a name="Page_155" id="Page_155">155</a></span>
+flora when the Bulgarian bacillus had been naturalised
+in the colon, and the bacillus persisted
+long after it had ceased to be administered.
+Specialists who have taken up the subject report
+the cure of many ailments through the agency
+of soured milk, and it seems to have entered upon
+a lengthening career of medical usefulness.</p>
+
+<p>The fact of so many old people being found in
+countries where soured milk is a staple of diet
+naturally raises the question as to whether its
+general use in other countries might not have a
+beneficial effect on health and longevity. Its
+usefulness as a remedial agent in certain diseases
+is already demonstrated; is there not a strong
+probability, amounting almost to a certainty,
+that its consumption by people in health would
+tend to ward off many ailments and prolong
+life? Of course there will be some for whom
+it is not suitable; there are people who cannot
+eat strawberries without discomfort, but no one
+thinks of prohibiting the general use of the fruit
+on that account. In the matter of diet the person
+in health, if he exercises ordinary care, may be
+left to find out for himself what suits him. The
+soured milk remedy is not a disagreeable one,
+as, when properly prepared, the article forms
+<span class='pagenum'><a name="Page_156" id="Page_156">156</a></span>
+both a pleasant and refreshing article of diet.
+The question of getting the right article, however,
+is a very important one. Milk is a splendid
+rearing ground for many bacteria, some of which
+are very injurious; among these may be pathological
+germs, the seeds of tuberculosis, enteritis,
+etc. The danger with soured milk is, that in the
+process of culture we develop the best condition
+for the increase of these when they preponderate,
+or when, through the use of bad cultures, the
+lactic-acid-producing bacteria are absent, or present
+only in small numbers. By the thorough
+boiling of the milk, we get rid of all living bacteria
+and nearly all spores or germs, and by scrupulous
+cleanliness in the vessels used&mdash;scalding or
+even boiling them, and allowing them to dry
+naturally in an inverted position&mdash;we greatly
+diminish the probability of infection with fresh
+injurious germs from the atmosphere. All depends
+on the purity of the culture employed;
+this can now be obtained, prepared in the most
+careful manner, from wholesale chemists making
+a speciality of its manufacture.</p>
+
+<p>As we have seen, even the Bulgarian bacillus
+is ultimately killed by the products of its own
+activity, and the natural corollary is, that the life
+<span class='pagenum'><a name="Page_157" id="Page_157">157</a></span>
+of cultures cannot be a long one. Only those
+cultures should be bought which are labelled with
+the date to which they are guaranteed to maintain
+their efficiency. With fresh good milk,
+careful boiling, scalding, and cleanliness with
+regard to the containing vessels, and the means
+of maintaining the incubating temperature for
+ten or twelve hours, there is not the slightest
+difficulty in preparing perfectly reliable soured
+milk. There are simple tests which will sufficiently
+guide the experimenter; the soured milk
+should not be too acid to the taste, and it has a
+flavour of its own by which its quality can be
+recognised. The litmus test-papers mentioned in
+the chapter on the chemistry of milk are very
+useful; both the red and the blue papers should
+be obtained and used first of all in testing the
+quality of the fresh milk. After incubation the
+soured milk should turn the blue paper decidedly
+red; if this does not occur, test it with the red
+paper; if the latter turns blue it is proof that the
+wrong fermentation has taken place&mdash;that putrefactive
+germs have gained the upper hand. The
+most probable explanation is, that the culture is
+bad, the Bulgarian bacillus is not present, or if
+so, only in small numbers. With these simple
+<span class='pagenum'><a name="Page_158" id="Page_158">158</a></span>
+tests, combined with proper care, one cannot
+go far wrong. The Eastern nations who prepare
+soured milk in various forms do not exercise the
+care we have predicated, but they seem to make
+the article of fairly constant and good quality.
+It has been suggested in explanation that, as the
+ordinary flora differs in different countries, the
+bacterial flora varies in a similar manner, and
+that in these Eastern countries injurious bacteria
+are not so prevalent in the atmosphere as they are
+with us.</p>
+
+<p>It is also said that the flavour of the soured
+milk prepared in Bulgaria is quite different from
+that prepared in Paris, London, or New York;
+one reason probably is that the "maya" or ferment
+used in Bulgaria contains several other
+organisms besides the Bulgarian bacillus, which
+raises the question whether a pure culture of one
+bacillus is the best to use.</p>
+
+<p>Professor Metchnikoff found that this bacillus
+alone had certain defects; it attacks fat and is
+apt to give a tallowy taste when cream is present
+in the milk. He therefore associated with it
+another lactic-acid-producing organism, and this
+combination is the basis of his culture called
+"lactobacilline." The presence of yeasts, which
+<span class='pagenum'><a name="Page_159" id="Page_159">159</a></span>
+occur in the Eastern ferments, has been advocated
+by some; the yeast in association with the lactic
+organisms produces a small amount of alcohol.
+The question of the composition of the culture
+will have to be fought out by the experts, but
+meantime, if we go to the right source, we have
+good enough cultures to go on with.</p>
+
+<p>A good deal can be said for the use of skimmed
+or separated milk instead of whole milk. Cream
+as a rule contains far more bacteria than the rest
+of the milk, and we therefore start from a surer
+foundation when it is removed; besides, the
+mechanical separator, now so largely used, removes
+slime and other impurities from the milk,
+and these also are hotbeds of bacteria.</p>
+
+<p>Soured milk may be taken at any time, the
+first thing in the morning, before or after meals,
+or the last thing at night. The quantity will
+vary with the individual, but from half a pint to
+a pint is a fair amount for daily use. If one
+wishes to have the maximum effect it is necessary
+for the time being to curtail the use of butcher's
+meat and substitute fish, yolk of eggs, and other
+similar foods; not much alcohol should be taken,
+and smoking might be reduced to a minimum.
+Those who cannot take even skimmed milk may
+<span class='pagenum'><a name="Page_160" id="Page_160">160</a></span>
+use whey in which to cultivate the bacillus; it
+is not desirable to employ the whey which has
+been separated by the use of rennet, as in cheese- or
+junket-making. A better article is obtained
+by adding a very small quantity of pure hydrochloric
+acid to milk which has been boiled, and
+then filtering through a sieve, which retains the
+curd while the liquid whey passes through; a
+pinch of soda is added to neutralise the excess of
+acid, and, after boiling, the liquid should turn
+red litmus paper blue; it is then ready for the
+addition of the culture and incubation in the
+same manner as with milk. A solution of malt&mdash;the
+extract dissolved in hot water is convenient&mdash;may
+also be used instead of milk, and strongly
+malted bread or biscuits are excellent to take with
+the soured milk or cultures in other mediums,
+to supply food for the bacillus in the form of malt
+sugar. Other sugars, cane or grape, are also very
+useful, and may be taken in the form of fruit
+juices, syrups, confections, jams, sweet puddings,
+etc.</p>
+
+<p>We lay stress on the use of soured milk or other
+cultures of the Bulgarian bacillus by people in
+health as a probable preventive of disease and a
+possible agent in the lengthening of life, but it
+<span class='pagenum'><a name="Page_161" id="Page_161">161</a></span>
+may be of interest to give a short account of its
+use by medical men in the treatment of various
+ailments. An English authority on the subject,
+Dr. Herschell, states that the symptoms of the
+poisoning of the system by the toxic substances
+produced by injurious bacteria in the large intestine
+may include headaches, misery and depression
+of spirits, drowsiness and stupor, giddiness,
+dimness of sight and dizziness, fatigue without
+obvious cause, both of the muscles and brain,
+fear, panic, and nervousness, disagreeable sensations
+in the limbs or face, such as numbness,
+tingling, or prickling, crawling sensation of weight
+or of heat or cold, dyspepsia of the sort where there
+is a deficiency of hydrochloric acid and pepsin
+in the gastric juice, accompanied by flabbiness
+and loss of power in the muscles of the stomach,
+and characterised by flatulence, nausea, loss of
+appetite, with discomfort and weight after food,
+furred tongue, emaciation, earthy colour of the
+skin, offensive perspiration and the other signs
+of biliousness, enlargement of the liver, and
+an&aelig;mia. These symptoms may have other causes,
+and when one or several of them are present a
+chemical and physical examination of the urine
+and f&aelig;ces is necessary to prove that they have
+<span class='pagenum'><a name="Page_162" id="Page_162">162</a></span>
+resulted from auto-intoxication. When this is
+shown the soured milk treatment is indicated,
+and many striking cures are detailed as witnesses
+to its efficacy. The liver and kidneys are the
+natural guardians of the body against the toxines
+we are speaking of, and frequently they are over-strained;
+the soured milk treatment greatly
+lightens their load. In malignant disease of the
+stomach, soured milk will frequently be retained
+when all other foods are rejected. In cases of
+neurasthenia and gout it has also proved of value,
+and in the "run-down" condition which is so
+common in middle life. Chronic diarrh&oelig;a and
+certain forms of constipation have in numerous
+instances yielded to the treatment, the whey
+culture being usually found the most suitable.
+Then, in some forms of an&aelig;mia, the lactic acid
+cultures have proved most successful, and, as a
+means of rendering the gastro-intestinal track
+aseptic previous to operations, they have proved
+of considerable value.</p>
+
+<p>If all this has been accomplished in a year or
+two, what may not we look forward to in the
+future when more extended use and experiment
+shall have more fully exhausted the possibilities
+of the cure? But if we follow the example of the
+<span class='pagenum'><a name="Page_163" id="Page_163">163</a></span>
+different nations who have so long used soured
+milk as a regular article of diet, does it not seem
+probable that we may eliminate some, at least, of
+the causes of ill-health that call for the intervention
+of the doctor?</p>
+
+<p>The human organism is by no means perfect;
+we have within us many defective parts, and some
+organs whose working seems to be against the
+welfare of the economy. It has now been clearly
+shown that one of the chief of these is the large
+intestine, as to the use of which only vague and
+unsatisfactory theories have been formed. There
+can be no doubt as to the damage which it frequently
+inflicts on the system, and, thanks to
+the researches of Professor Metchnikoff and other
+investigators, we seem to be in possession of a
+natural remedy which is sufficient to deal with
+the evils it produces.</p>
+
+<h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_1" id="Footnote_1"></a><a href="#FNanchor_1"><span class="label">1</span></a> <i>Discoveries in Nineveh and Babylon</i>, by Layard, chap. xiii.</p></div>
+
+<div class="footnote"><p><a name="Footnote_2" id="Footnote_2"></a><a href="#FNanchor_2"><span class="label">2</span></a> Ex. xviii. and xxiii.; Lev. ii. and xi.</p></div>
+
+<div class="footnote"><p><a name="Footnote_3" id="Footnote_3"></a><a href="#FNanchor_3"><span class="label">3</span></a> <i>Encyclo. Biblica.</i></p></div>
+
+<div class="footnote"><p><a name="Footnote_4" id="Footnote_4"></a><a href="#FNanchor_4"><span class="label">4</span></a> Burckhardt and Doughty.</p></div>
+
+<div class="footnote"><p><a name="Footnote_5" id="Footnote_5"></a><a href="#FNanchor_5"><span class="label">5</span></a> <i>Annals of Dairying in Europe</i>, by Loudon M. Douglas.</p></div>
+
+<div class="footnote"><p><a name="Footnote_6" id="Footnote_6"></a><a href="#FNanchor_6"><span class="label">6</span></a> Burckhardt, <i>Bedouins</i>.</p></div>
+
+<div class="footnote"><p><a name="Footnote_7" id="Footnote_7"></a><a href="#FNanchor_7"><span class="label">7</span></a> This word is spelt in a great many ways by different writers: <i>Yoghourt</i>
+would seem to be the one most favoured.&mdash;<span class="smcap">Author.</span></p></div>
+
+<div class="footnote"><p><a name="Footnote_8" id="Footnote_8"></a><a href="#FNanchor_8"><span class="label">8</span></a> <i>Damascus and Palmyra</i>, by Chas. G. Addison, 1838.</p></div>
+
+<div class="footnote"><p><a name="Footnote_9" id="Footnote_9"></a><a href="#FNanchor_9"><span class="label">9</span></a> <i>Travels in Syria and the Holy Land</i>, by Burckhardt, 1822.</p></div>
+
+<div class="footnote"><p><a name="Footnote_10" id="Footnote_10"></a><a href="#FNanchor_10"><span class="label">10</span></a> <i>Lands of the Saracens</i>, by B. Taylor.</p></div>
+
+<div class="footnote"><p><a name="Footnote_11" id="Footnote_11"></a><a href="#FNanchor_11"><span class="label">11</span></a> <i>Travels through Sweden, Finland, and Lapland and to the North
+Cape in the years 1798 and 1799</i>, by Joseph Acerbi, 1802.</p></div>
+
+<div class="footnote"><p><a name="Footnote_12" id="Footnote_12"></a><a href="#FNanchor_12"><span class="label">12</span></a> Letter to the author, from Mr. H. Cavendish Venables, British
+Vice-Consul at Varna.</p></div>
+
+<div class="footnote"><p><a name="Footnote_13" id="Footnote_13"></a><a href="#FNanchor_13"><span class="label">13</span></a> <i>One Hundred and Twenty Years of Life</i>, by Reinhardt; <i>The Secret
+of Longevity</i>, by an F.R.M.S.</p></div>
+
+<div class="footnote"><p><a name="Footnote_14" id="Footnote_14"></a><a href="#FNanchor_14"><span class="label">14</span></a> <i>Foods, their Composition and Analysis</i>, by A. W. Blyth.</p></div>
+
+<div class="footnote"><p><a name="Footnote_15" id="Footnote_15"></a><a href="#FNanchor_15"><span class="label">15</span></a> <i>Dictionary of Applied Chemistry</i>, by T. E. Thorpe, C.B.</p></div>
+
+<div class="footnote"><p><a name="Footnote_16" id="Footnote_16"></a><a href="#FNanchor_16"><span class="label">16</span></a> <i>Koumiss or Fermented Mares' Milk and its Uses, and the Treatment
+and Cure of Pulmonary Consumption and Other Diseases</i>, by L. Carrick,
+M.D., 1881.</p></div>
+
+<div class="footnote"><p><a name="Footnote_17" id="Footnote_17"></a><a href="#FNanchor_17"><span class="label">17</span></a> <i>Transactions of the Royal Society of Edinburgh</i>, vol. i.</p></div>
+
+<div class="footnote"><p><a name="Footnote_18" id="Footnote_18"></a><a href="#FNanchor_18"><span class="label">18</span></a> Clarke's <i>Travels</i>, 1810.</p></div>
+
+<div class="footnote"><p><a name="Footnote_19" id="Footnote_19"></a><a href="#FNanchor_19"><span class="label">19</span></a> 1845.</p></div>
+
+<div class="footnote"><p><a name="Footnote_20" id="Footnote_20"></a><a href="#FNanchor_20"><span class="label">20</span></a> <i>Dictionary of Applied Chemistry</i>, by Thorpe.</p></div>
+
+<div class="footnote"><p><a name="Footnote_21" id="Footnote_21"></a><a href="#FNanchor_21"><span class="label">21</span></a> A leathern bottle.</p></div>
+
+<div class="footnote"><p><a name="Footnote_22" id="Footnote_22"></a><a href="#FNanchor_22"><span class="label">22</span></a> "I have brought forward Tchembulatof's receipt, which differs
+from Bogoyavlensky's in the use of a larger quantity of millet-flour,
+and in the boiling of the latter apart from the milk. Dr. Postnikof's
+plan is the following: Half a pound of millet-flour and a quarter of a
+pound of malt are mixed with a sufficient quantity of honey to form a
+paste, which is put into a clean jar, covered with a linen cloth, and
+placed on a warm stove. The mass soon begins to rise, and is then taken
+out, wrapped in a piece of muslin, and dropped into a clean earthenware
+vessel, containing about a quart of new mares' milk, which is
+placed in the same temperature that the paste was kept in. As soon as
+signs of fermentation begin to show themselves in the fluid, the paste
+must be removed, while the milk, after being stirred, should be left
+in the same temperature till bubbles appear (only in very small quantities)
+on its surface. The ferment is then ready."</p></div>
+
+<div class="footnote"><p><a name="Footnote_23" id="Footnote_23"></a><a href="#FNanchor_23"><span class="label">23</span></a> <i>Food and the Principles of Dietetics.</i></p></div>
+
+<div class="footnote"><p><a name="Footnote_24" id="Footnote_24"></a><a href="#FNanchor_24"><span class="label">24</span></a> <i>Food and the Principles of Dietetics</i>, by Robert Hutchison, M.D.</p></div>
+
+<div class="footnote"><p><a name="Footnote_25" id="Footnote_25"></a><a href="#FNanchor_25"><span class="label">25</span></a> <i>Bacteria in Milk and its Products</i>, by Conn.</p></div>
+
+<div class="footnote"><p><a name="Footnote_26" id="Footnote_26"></a><a href="#FNanchor_26"><span class="label">26</span></a> <i>Dict. App. Chem.</i>, Thorpe.</p></div>
+
+<div class="footnote"><p><a name="Footnote_27" id="Footnote_27"></a><a href="#FNanchor_27"><span class="label">27</span></a> <i>Nature</i>, July 23, 1884.</p></div>
+
+<div class="footnote"><p><a name="Footnote_28" id="Footnote_28"></a><a href="#FNanchor_28"><span class="label">28</span></a> <i>The Exploration of the Caucasus</i>, by Duncan W. Freshfield, 1896.</p></div>
+
+<div class="footnote"><p><a name="Footnote_29" id="Footnote_29"></a><a href="#FNanchor_29"><span class="label">29</span></a> Quoted by George M. Sternberg, M.D., LL.D., <i>Text-Book of
+Bacteriology</i>, 1898.</p></div>
+
+<div class="footnote"><p><a name="Footnote_30" id="Footnote_30"></a><a href="#FNanchor_30"><span class="label">30</span></a> <i>Encyclo. Biblica.</i></p></div>
+
+<div class="footnote"><p><a name="Footnote_31" id="Footnote_31"></a><a href="#FNanchor_31"><span class="label">31</span></a> Conn.</p></div>
+
+<div class="footnote"><p><a name="Footnote_32" id="Footnote_32"></a><a href="#FNanchor_32"><span class="label">32</span></a> <i>Cyclo. of Biblical Lit.</i>, M'Clintock and Strong, and Burckhardt's
+<i>Arabia</i>.</p></div>
+
+<div class="footnote"><p><a name="Footnote_33" id="Footnote_33"></a><a href="#FNanchor_33"><span class="label">33</span></a> <i>The Indian Medical Gazette</i>, Sept., 1909, "A New Lactic Acid producing
+Streptothrix," by Gopal Ch. Chatterjee, M.B.</p></div>
+
+<div class="footnote"><p><a name="Footnote_34" id="Footnote_34"></a><a href="#FNanchor_34"><span class="label">34</span></a> In their studies on Leben in the <i>Annales de l'Institut Pasteur</i> of
+1899, Rist and Khoury, in speaking of the amount of lactic acid produced
+by <i>Streptobacillus lebenis</i> in milk, say "Nous avons mesur&eacute;
+cette acidit&eacute; dans une culture sur petit lait de vingt-quatre heures;
+elle &eacute;tait .261 grms. per cent. exprim&eacute;e en acide lactique," which will
+make the amount of lactic acid produced in one litre of milk 2.61 grms.
+The production of this small amount of lactic acid does not tally with
+the ordinary view of the vigorous lactic-acid-producing power of the
+bacillus.</p></div>
+
+<div class="footnote"><p><a name="Footnote_35" id="Footnote_35"></a><a href="#FNanchor_35"><span class="label">35</span></a> <i>Prolongation of Life.</i></p></div>
+
+<div class="footnote"><p><a name="Footnote_36" id="Footnote_36"></a><a href="#FNanchor_36"><span class="label">36</span></a> <i>Prolongation of Life.</i></p></div>
+
+<div class="footnote"><p><a name="Footnote_37" id="Footnote_37"></a><a href="#FNanchor_37"><span class="label">37</span></a> An accurate census of Bulgaria is being prepared and will exhibit
+the cases of long life in that country.</p></div>
+
+<div class="footnote"><p><a name="Footnote_38" id="Footnote_38"></a><a href="#FNanchor_38"><span class="label">38</span></a> See A. Rosam, <i>&Ouml;sterreichische Molkerei Zeitung</i>, 15, p. 31.</p></div>
+
+<div class="footnote"><p><a name="Footnote_39" id="Footnote_39"></a><a href="#FNanchor_39"><span class="label">39</span></a> <i>Revue g&eacute;n&eacute;rale du Lait</i>, vii., pp. 8 and 9 (letter from Dr. Otakar
+Laxa of Prague, Bohemia, to the author).</p></div>
+
+<div class="footnote"><p><a name="Footnote_40" id="Footnote_40"></a><a href="#FNanchor_40"><span class="label">40</span></a> <i>On the Prolongation of Human Life</i>, by &Eacute;lie Metchnikoff; also <i>The
+Century Magazine</i>, Nov., 1909, "The Utility of Lactic Microbes," by
+the same author.</p></div>
+
+<div class="footnote"><p><a name="Footnote_41" id="Footnote_41"></a><a href="#FNanchor_41"><span class="label">41</span></a> <i>Century Magazine</i>, Nov., 1909.</p></div>
+
+<div class="footnote"><p><a name="Footnote_42" id="Footnote_42"></a><a href="#FNanchor_42"><span class="label">42</span></a> See <i>Annals of Dairying in Europe</i>, by Loudon M. Douglas.</p></div>
+
+<div class="footnote"><p><a name="Footnote_43" id="Footnote_43"></a><a href="#FNanchor_43"><span class="label">43</span></a> Adapted from a report by Robert E. Turnbull, in <i>Live Stock
+Journal</i>.</p></div>
+
+<div class="footnote"><p><a name="Footnote_44" id="Footnote_44"></a><a href="#FNanchor_44"><span class="label">44</span></a> <i>Facts about Milk</i>, by R. A. Pearson, B.S., Washington.</p></div>
+
+<div class="footnote"><p><a name="Footnote_45" id="Footnote_45"></a><a href="#FNanchor_45"><span class="label">45</span></a> <i>Care and Handling of Milk</i>, Marshall and Wright, Bulletin 221,
+Michigan, 1904.</p></div>
+
+<div class="footnote"><p><a name="Footnote_46" id="Footnote_46"></a><a href="#FNanchor_46"><span class="label">46</span></a> <i>Journal of the Royal Society of Arts</i>, March 6, 1908&mdash;"Modern
+Dairy Practice," by Loudon M. Douglas.</p></div>
+
+<div class="footnote"><p><a name="Footnote_47" id="Footnote_47"></a><a href="#FNanchor_47"><span class="label">47</span></a> Skolotowski, <i>Wratsch</i>, 1883 (Russian), from Codwyssozki.</p></div>
+
+<div class="footnote"><p><a name="Footnote_48" id="Footnote_48"></a><a href="#FNanchor_48"><span class="label">48</span></a> Podowyssozki, <i>Zeitschr. f. diat. u. physik. Therapie</i> vol. v., 1901,
+p. 570.</p></div>
+
+<div class="footnote"><p><a name="Footnote_49" id="Footnote_49"></a><a href="#FNanchor_49"><span class="label">49</span></a> Hammersten, <i>Jahresb. u. d. Fortsch. d. Tierchem</i>, 1886, Bd. 16, p.
+163.</p></div>
+
+<div class="footnote"><p><a name="Footnote_50" id="Footnote_50"></a><a href="#FNanchor_50"><span class="label">50</span></a> Essaulow, <i>Dissert. Moscow</i>, 1895, <i>Abstr., Koch's Jahresb.</i>, 1895,
+Bd. 6, p. 222.</p></div>
+
+<div class="footnote"><p><a name="Footnote_51" id="Footnote_51"></a><a href="#FNanchor_51"><span class="label">51</span></a> Kern, <i>Bulletin Soc. des Naturalistes de Moscow</i>, 1881, 3, p. 141.</p></div>
+
+<div class="footnote"><p><a name="Footnote_52" id="Footnote_52"></a><a href="#FNanchor_52"><span class="label">52</span></a> Krannhals, <i>Deutsch. Arch. f. Klin. Med.</i>, 1884, Bd. 35, p. 18.</p></div>
+
+<div class="footnote"><p><a name="Footnote_53" id="Footnote_53"></a><a href="#FNanchor_53"><span class="label">53</span></a> Beijerinck, <i>Centralbl. Bakt. Par.</i>, 1889, Bd. 6, p. 44.</p></div>
+
+<div class="footnote"><p><a name="Footnote_54" id="Footnote_54"></a><a href="#FNanchor_54"><span class="label">54</span></a> Scholl, <i>Die Milch</i>, Wiesbaden, 1891, p. 38.</p></div>
+
+<div class="footnote"><p><a name="Footnote_55" id="Footnote_55"></a><a href="#FNanchor_55"><span class="label">55</span></a> Adametz, <i>Centralbl. Bakt. Par.</i>, 1889, Bd. 5, p. 116.</p></div>
+
+<div class="footnote"><p><a name="Footnote_56" id="Footnote_56"></a><a href="#FNanchor_56"><span class="label">56</span></a> Freudenreich, <i>Landw. Jahrb. d. Schweiz.</i>, 1896, vol. x., p. 1.</p></div>
+
+<div class="footnote"><p><a name="Footnote_57" id="Footnote_57"></a><a href="#FNanchor_57"><span class="label">57</span></a> Nikolaiewa, <i>Annals of the Botan. Lab. of the Med. Inst. for Women</i>,
+No. 10. St. Petersburg, 1907.</p></div>
+
+<div class="footnote"><p><a name="Footnote_58" id="Footnote_58"></a><a href="#FNanchor_58"><span class="label">58</span></a> Kuntze, <i>Centralbl. Bakt. Par.</i>, 1909, 24, p. 101.</p></div>
+
+<div class="footnote"><p><a name="Footnote_59" id="Footnote_59"></a><a href="#FNanchor_59"><span class="label">59</span></a> See Chap. II.</p></div>
+
+<div class="footnote"><p><a name="Footnote_60" id="Footnote_60"></a><a href="#FNanchor_60"><span class="label">60</span></a> Rubinsky, <i>Centralbl. Bakt. Par. II.</i>, 1910, vol. xxviii., p. 161.</p></div>
+
+<div class="footnote"><p><a name="Footnote_61" id="Footnote_61"></a><a href="#FNanchor_61"><span class="label">61</span></a> Biel, <i>Jahresb. &uuml;. d. Fortschr. d. Tierchem</i>, 1886, 16, p. 159.</p></div>
+
+<div class="footnote"><p><a name="Footnote_62" id="Footnote_62"></a><a href="#FNanchor_62"><span class="label">62</span></a> Allik, <i>Dissertat. Dorpat.</i>, 1896, 19, p. 303.</p></div>
+
+<div class="footnote"><p><a name="Footnote_63" id="Footnote_63"></a><a href="#FNanchor_63"><span class="label">63</span></a> Fleischmann, <i>Lehrb. d. Milchwirtschaft</i>, 2d edition. Bremen, 1898.</p></div>
+
+<div class="footnote"><p><a name="Footnote_64" id="Footnote_64"></a><a href="#FNanchor_64"><span class="label">64</span></a> Rist and Khoury, <i>Annal. Pasteur</i>, 1902, 16, p. 65.</p></div>
+
+<div class="footnote"><p><a name="Footnote_65" id="Footnote_65"></a><a href="#FNanchor_65"><span class="label">65</span></a> Guerbet, <i>Comptes Rendus</i>, 1906.</p></div>
+
+<div class="footnote"><p><a name="Footnote_66" id="Footnote_66"></a><a href="#FNanchor_66"><span class="label">66</span></a> Weigmann, <i>Lafar's Handb. d. Techn. Mykol.</i>, 2d edit., 1905, vol.
+ii., p. 134.</p></div>
+
+<div class="footnote"><p><a name="Footnote_67" id="Footnote_67"></a><a href="#FNanchor_67"><span class="label">67</span></a> Emmerling, <i>Cent. Bakt. Par.</i> 1898, vol. iv., p. 418.</p></div>
+
+<div class="footnote"><p><a name="Footnote_68" id="Footnote_68"></a><a href="#FNanchor_68"><span class="label">68</span></a> Lindner, <i>Mikroscop. Betriebscontrolle, i. d. G&auml;rungsgew</i>, 3d edit.,
+Berlin, 1901.</p></div>
+
+<div class="footnote"><p><a name="Footnote_69" id="Footnote_69"></a><a href="#FNanchor_69"><span class="label">69</span></a> Kalantharianz, <i>Dissert. Berlin</i>, Abs. in <i>Koch's Jahresb.</i>, 1898, Bd. 9.</p></div>
+
+<div class="footnote"><p><a name="Footnote_70" id="Footnote_70"></a><a href="#FNanchor_70"><span class="label">70</span></a> Luerssen and K&uuml;hn, <i>Centralbl. Bakt.</i></p></div>
+
+<div class="footnote"><p><a name="Footnote_71" id="Footnote_71"></a><a href="#FNanchor_71"><span class="label">71</span></a> Piorkowski, <i>Sitzungsber. der Berl. med. Ges.</i>, Nov., 1907.</p></div>
+
+<div class="footnote"><p><a name="Footnote_72" id="Footnote_72"></a><a href="#FNanchor_72"><span class="label">72</span></a> Metchnikoff, <i>The Prolongation of Life.</i></p></div>
+
+<div class="footnote"><p><a name="Footnote_73" id="Footnote_73"></a><a href="#FNanchor_73"><span class="label">73</span></a> Grigoroff, <i>Revue M&eacute;dicale de la Suisse Romande</i>, 1905, p. 10.</p></div>
+
+<div class="footnote"><p><a name="Footnote_74" id="Footnote_74"></a><a href="#FNanchor_74"><span class="label">74</span></a> Grixoni, <i>Abstr. Cent. Bakt. Par.</i> 11, 15, p. 750.</p></div>
+
+<div class="footnote"><p><a name="Footnote_75" id="Footnote_75"></a><a href="#FNanchor_75"><span class="label">75</span></a> Freudenreich and Jensen, <i>Cent. Bakt. Par.</i> 11, 1897, 3, 545.</p></div>
+
+<div class="footnote"><p><a name="Footnote_76" id="Footnote_76"></a><a href="#FNanchor_76"><span class="label">76</span></a> Moro, <i>Wien. klin. Wochenschr.</i>, 5, 1900.</p></div>
+
+<div class="footnote"><p><a name="Footnote_77" id="Footnote_77"></a><a href="#FNanchor_77"><span class="label">77</span></a> Makrinoff, <i>Cent. Bakt. Par.</i> 11, 1910, vol. xxvi., p. 374.</p></div>
+
+<div class="footnote"><p><a name="Footnote_78" id="Footnote_78"></a><a href="#FNanchor_78"><span class="label">78</span></a> White and Avery, <i>Cent. Bakt. Par.</i> II, 1909, vol. xxv., p. 161.</p></div>
+
+<div class="footnote"><p><a name="Footnote_79" id="Footnote_79"></a><a href="#FNanchor_79"><span class="label">79</span></a> Hastings and Hammer, <i>Research Bull., Wisconsin Experimental
+Station</i>, 6, 1909.</p></div>
+
+<div class="footnote"><p><a name="Footnote_80" id="Footnote_80"></a><a href="#FNanchor_80"><span class="label">80</span></a> Boutroux, <i>Comp. Rend.</i>, 86, 1905, 605.</p></div>
+
+<div class="footnote"><p><a name="Footnote_81" id="Footnote_81"></a><a href="#FNanchor_81"><span class="label">81</span></a> Richet, <i>Comp. Rend.</i>, 86, 1905, 550.</p></div>
+
+<div class="footnote"><p><a name="Footnote_82" id="Footnote_82"></a><a href="#FNanchor_82"><span class="label">82</span></a> Koning, <i>Milchw. Zentralbl.</i>, 1905, 1, 280.</p></div>
+
+<div class="footnote"><p><a name="Footnote_83" id="Footnote_83"></a><a href="#FNanchor_83"><span class="label">83</span></a> Heinemann, <i>Centralbl. Bakt. Par.</i> 1908, 21, 57.</p></div>
+
+<div class="footnote"><p><a name="Footnote_84" id="Footnote_84"></a><a href="#FNanchor_84"><span class="label">84</span></a> Chap. I.</p></div>
+
+<div class="footnote"><p><a name="Footnote_85" id="Footnote_85"></a><a href="#FNanchor_85"><span class="label">85</span></a> Metchnikoff, <i>The Prolongation of Life</i>, 1908, p. 161.</p></div>
+
+
+<hr />
+
+<p><span class='pagenum'><a name="Page_165" id="Page_165">165</a></span></p>
+<h2>INDEX</h2>
+
+<ul class="IX">
+<li><span style="margin-left: 6em;">
+A</span>
+</li><li>
+Acerbi, <a href="#Page_8">8</a>
+</li><li>
+Acidity of milk, <a href="#Page_64">64</a>
+</li><li>
+Adametz on keffir, <a href="#Page_92">92</a>
+</li><li>
+Albumen, <a href="#Page_52">52</a>
+</li><li>
+Alcoholic fermentation, <a href="#Page_17">17</a>, <a href="#Page_84">84</a>
+</li><li>
+Allen &amp; Hanbury's apparatus, <a href="#Page_132">132</a>
+</li><li>
+American incubating apparatus, <a href="#Page_149">149</a>
+</li><li>
+Analysis of milk, <a href="#Page_48">48</a>, <a href="#Page_61">61</a>
+</li><li>
+Aneyza Bedouins, <a href="#Page_2">2</a>
+</li><li>
+Arabs, <a href="#Page_2">2</a>
+</li><li>
+Arak&agrave;, <a href="#Page_106">106</a>
+</li><li>
+Ash of milk, <a href="#Page_56">56</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+B</span>
+</li><li>&nbsp;
+</li><li>
+<i>Bacillus acidi lactici</i>, <a href="#Page_107">107</a>, <a href="#Page_112">112</a>
+</li><li>
+<i>Bacillus acidophilus</i>, <a href="#Page_110">110</a>, <a href="#Page_112">112</a>
+</li><li>
+<i>Bacillus bulgaricus</i>, <a href="#Page_39">39</a>, <a href="#Page_46">46</a>, <a href="#Page_82">82</a>, <a href="#Page_108">108</a>, <a href="#Page_110">110</a>, <a href="#Page_123">123</a>, <a href="#Page_154">154</a>
+</li><li>
+<i>Bacillus casei</i>, <a href="#Page_113">113</a>
+</li><li>
+<i>Bacillus caucasicus</i>, <a href="#Page_92">92</a>, <a href="#Page_94">94</a>, <a href="#Page_95">95</a>, <a href="#Page_119">119</a>
+</li><li>
+<i>Bacillus caucasina</i>, <a href="#Page_39">39</a>
+</li><li>
+<i>Bacillus coli</i>, <a href="#Page_45">45</a>
+</li><li>
+<i>Bacillus esterificans</i>, <a href="#Page_96">96</a>
+</li><li>
+<i>Bacillus keffir</i>, <a href="#Page_96">96</a>, <a href="#Page_97">97</a>
+</li><li>
+<i>Bacillus lebenis</i>, <a href="#Page_105">105</a>
+</li><li>
+<i>Bacillus matzoon</i>, <a href="#Page_109">109</a>, <a href="#Page_110">110</a>
+</li><li>
+Bacillus of long life, <a href="#Page_46">46</a>
+</li><li>
+<i>Bacillus putrificus</i>, <a href="#Page_122">122</a>
+</li><li>
+<i>Bacillus subtilis</i>, <a href="#Page_90">90</a>, <a href="#Page_92">92</a>, <a href="#Page_107">107</a>
+</li><li>
+Bacteria in milk, <a href="#Page_76">76</a>
+</li><li>
+Bacteriology of fermented milks, <a href="#Page_84">84</a>
+</li><li>
+<i>Bacterium acidi lactici</i>, <a href="#Page_92">92</a>, <a href="#Page_96">96</a>
+</li><li>
+<i>Bacterium a&euml;rogenes</i>, <a href="#Page_92">92</a>, <a href="#Page_96">96</a>
+</li><li>
+<i>Bacterium coli commune</i>, <a href="#Page_119">119</a>, <a href="#Page_122">122</a>
+</li><li>
+<i>Bacterium sardous</i>, <a href="#Page_110">110</a>, <a href="#Page_111">111</a>
+</li><li>
+Balkan Peninsula, <a href="#Page_4">4</a>
+</li><li>
+Bedouins, <a href="#Page_2">2</a>
+</li><li>
+Beijerinck on keffir, <a href="#Page_91">91</a>
+</li><li>
+Biestings, <a href="#Page_63">63</a>
+</li><li>
+Biology of the keffir grain, <a href="#Page_90">90</a>
+</li><li>
+Blood, water contents of, <a href="#Page_50">50</a>
+</li><li>
+Bourgoul, <a href="#Page_6">6</a>
+</li><li>
+Bulgarian maya, <a href="#Page_10">10</a>, <a href="#Page_109">109</a>
+</li><li>
+Bulgaricus group, cultural characteristics of, <a href="#Page_115">115</a>
+</li><li>
+Burckhardt, <a href="#Page_6">6</a>
+</li><li>
+Butin, <a href="#Page_51">51</a>
+</li><li>
+Butyric acid fermentation, <a href="#Page_16">16</a>
+</li><li>
+Butyrin, <a href="#Page_51">51</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+C</span>
+</li><li>&nbsp;
+</li><li>
+Camels' milk, <a href="#Page_2">2</a>
+</li><li>
+Caprinin, <a href="#Page_51">51</a>
+</li><li>
+Capronin, <a href="#Page_51">51</a>
+</li><li>
+Caprylin, <a href="#Page_51">51</a>
+</li><li>
+Carrick on koumiss, <a href="#Page_18">18</a>
+</li><li>
+Casein, <a href="#Page_52">52</a>, <a href="#Page_53">53</a>
+</li><li>
+Centenarians in Servia, Bulgaria, and Roumania, <a href="#Page_41">41</a>
+</li><li>
+Chatterjee on Dadhi, <a href="#Page_38">38</a>
+</li><li>
+Chemistry of milk, <a href="#Page_47">47</a>
+</li><li>
+Chocolate preparations and the soured-milk bacillus, <a href="#Page_137">137</a>
+</li><li>
+Citrates in milk, <a href="#Page_57">57</a>
+</li><li>
+Clay, Paget &amp; Company's apparatus, <a href="#Page_132">132</a>
+</li><li>
+Coagulation of casein, <a href="#Page_59">59</a>
+</li><li>
+<i>Colitis</i>, <a href="#Page_45">45</a>
+</li><li>
+Colostrum, <a href="#Page_63">63</a>
+</li><li>
+Constituents of milk, <a href="#Page_48">48</a>
+</li><li>
+Continuous apparatus for producing soured milk, <a href="#Page_81">81</a>
+</li><li>
+Creamometer, <a href="#Page_62">62</a>
+</li><li><p><span class='pagenum'><a name="Page_166" id="Page_166">166</a></span></p>
+</li><li><span style="margin-left: 6em;">
+D</span>
+</li><li>&nbsp;
+</li><li>
+Dadhi, <a href="#Page_15">15</a>, <a href="#Page_38">38</a>
+</li><li>
+Dairy Machinery &amp; Construction Company's apparatus, <a href="#Page_80">80</a>, <a href="#Page_82">82</a>
+</li><li>
+Dairy Outfit Company's apparatus, <a href="#Page_145">145</a>
+</li><li>
+Dairy Supply Company's apparatus, <a href="#Page_143">143</a>;
+<ul><li>
+  steriliser, <a href="#Page_148">148</a>
+</li></ul>
+</li><li>
+Dirt in milk, <a href="#Page_63">63</a>
+</li><li>
+Diseases of keffir grains, <a href="#Page_97">97</a>
+</li><li>
+<i>Dispora caucasia</i>, <a href="#Page_34">34</a>, <a href="#Page_90">90</a>
+</li><li>
+Dried sour milk, <a href="#Page_5">5</a>
+</li><li>
+Duclaux, <a href="#Page_51">51</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+E</span>
+</li><li>&nbsp;
+</li><li>
+Edgar's "Lactogenerator," <a href="#Page_143">143</a>
+</li><li>
+Eggs, yolk of, <a href="#Page_52">52</a>
+</li><li>
+<i>Enteritis</i>, <a href="#Page_45">45</a>
+</li><li>
+Enzymes in milk, <a href="#Page_57">57</a>
+</li><li>
+Equipment for town's dairy, <a href="#Page_80">80</a>
+</li><li>
+Essaulow on keffir, <a href="#Page_89">89</a>, <a href="#Page_92">92</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+F</span>
+</li><li>&nbsp;
+</li><li>
+Fat of milk, <a href="#Page_50">50</a>
+</li><li>
+Ferments at the altar, <a href="#Page_3">3</a>
+</li><li>
+Fl&uuml;gge, <a href="#Page_35">35</a>
+</li><li>
+Freshfield on keffir, <a href="#Page_33">33</a>
+</li><li>
+Freudenreich, <a href="#Page_92">92</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+G</span>
+</li><li>&nbsp;
+</li><li>
+Gaseous fermentation, <a href="#Page_84">84</a>
+</li><li>
+Gay-Lussac, <a href="#Page_17">17</a>
+</li><li>
+Gioddu, <a href="#Page_107">107</a>
+</li><li>
+Globulin, <a href="#Page_54">54</a>
+</li><li>
+Grieve, Dr. John, on koumiss, <a href="#Page_19">19</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+H</span>
+</li><li>&nbsp;
+</li><li>
+Hammerstein on keffir, <a href="#Page_89">89</a>
+</li><li>
+Handling of milk, <a href="#Page_68">68</a>
+</li><li>
+Health and disease, <a href="#Page_151">151</a>
+</li><li>
+Hearson &amp; Company's "Lactobator," <a href="#Page_141">141</a>
+</li><li>
+Hebrews, <a href="#Page_3">3</a>
+</li><li>
+Houran, inhabitants of, <a href="#Page_6">6</a>
+</li><li>
+Hueppe, <a href="#Page_16">16</a>
+</li><li>
+Hutchinson, Dr. H. B., bacillus from English market milk, <a href="#Page_120">120</a>
+</li><li>
+Hutchison on koumiss, <a href="#Page_30">30</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+I</span>
+</li><li>&nbsp;
+</li><li>
+
+Ice chest, <a href="#Page_136">136</a>
+</li><li>
+Impure cultures, <a href="#Page_158">158</a>
+</li><li>
+Incubators, <a href="#Page_141">141</a>
+</li><li>
+India, <a href="#Page_1">1</a>
+</li><li>
+International Dairy Federation, <a href="#Page_68">68</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+J</span>
+</li><li>&nbsp;
+</li><li>
+Jebours, <a href="#Page_3">3</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+K</span>
+</li><li>&nbsp;
+</li><li>
+Kalmucks, <a href="#Page_20">20</a>
+</li><li>
+Keffir, <a href="#Page_15">15</a>, <a href="#Page_32">32</a>, <a href="#Page_85">85</a>;
+<ul><li>
+  old, <a href="#Page_88">88</a>
+</li></ul>
+</li><li>
+Keffir grain, biology of, <a href="#Page_90">90</a>
+</li><li>
+Kephir, <a href="#Page_34">34</a>, <a href="#Page_85">85</a>.
+<ul><li>
+  <i>See also</i> Keffir.
+</li></ul>
+</li><li>
+Keshk, <a href="#Page_6">6</a>
+</li><li>
+Keshk-leben, <a href="#Page_6">6</a>
+</li><li>
+Koumiss, <a href="#Page_15">15</a>, <a href="#Page_18">18</a>;
+<ul><li>
+  Bogoyavlensky's method of preparation, <a href="#Page_28">28</a>, <a href="#Page_98">98</a>;
+</li><li>
+  analysis, <a href="#Page_102">102</a>;
+</li><li>
+  artificial, <a href="#Page_102">102</a>
+</li></ul>
+</li><li>
+Krannhals on keffir, <a href="#Page_91">91</a>
+</li><li>
+Kuntze, <a href="#Page_95">95</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+L</span>
+</li><li>&nbsp;
+</li><li>
+Lactic acid, bacillus, <a href="#Page_16">16</a>;
+<ul><li>
+  cultures, <a href="#Page_55">55</a>;
+</li><li>
+  fermentation, <a href="#Page_16">16</a>, <a href="#Page_84">84</a>;
+</li><li>
+  Ferments apparatus, <a href="#Page_131">131</a>
+</li></ul>
+</li><li>
+"Lacto" apparatus, <a href="#Page_145">145</a>
+</li><li>
+"Lactobacilline," <a href="#Page_158">158</a>
+</li><li>
+<i>Lactobac. caucasicus</i>, <a href="#Page_91">91</a>
+</li><li>
+<i>Lactobacillus keffir</i>, <a href="#Page_94">94</a>
+</li><li>
+Lactometer, <a href="#Page_64">64</a>
+</li><li>
+Lapland, <a href="#Page_8">8</a>
+</li><li>
+Laurin, <a href="#Page_51">51</a>
+</li><li>
+Layard, <a href="#Page_2">2</a>
+</li><li>
+Leben, <a href="#Page_15">15</a>, <a href="#Page_37">37</a>, <a href="#Page_104">104</a>
+</li><li>
+Leben Ra&iuml;b, <a href="#Page_104">104</a>
+</li><li>
+Lecithin, <a href="#Page_52">52</a>
+</li><li>
+"Le Ferment" apparatus, <a href="#Page_128">128</a>
+</li><li>
+Liebig, <a href="#Page_17">17</a>
+</li><li>
+Longevity, <a href="#Page_155">155</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+M</span>
+</li><li><p><span class='pagenum'><a name="Page_167" id="Page_167">167</a></span></p>
+</li><li>
+Mares' milk, <a href="#Page_24">24</a>
+</li><li>
+Matzoon, <a href="#Page_15">15</a>, <a href="#Page_38">38</a>, <a href="#Page_106">106</a>
+</li><li>
+Maya, <a href="#Page_42">42</a>;
+<ul><li>
+  Bulgarian, <a href="#Page_10">10</a>
+</li></ul>
+</li><li>
+Maya Bulgare Company's apparatus, <a href="#Page_131">131</a>
+</li><li>
+Meeresy, <a href="#Page_5">5</a>
+</li><li>
+Metchnikoff, <a href="#Page_34">34</a>, <a href="#Page_40">40</a>, <a href="#Page_44">44</a>, <a href="#Page_121">121</a>, <a href="#Page_158">158</a>, <a href="#Page_163">163</a>
+</li><li>
+Micro-organisms, discovery of, <a href="#Page_13">13</a>
+</li><li>
+Middle Ages, <a href="#Page_13">13</a>
+</li><li>
+Milk-filling apparatus for bottles, <a href="#Page_82">82</a>
+</li><li>
+Milk, general properties of, <a href="#Page_57">57</a>;
+<ul><li>
+  of different animals, <a href="#Page_60">60</a>;
+</li><li>
+  supply of the United Kingdom, <a href="#Page_69">69</a>;
+</li><li>
+  industry in the United States, <a href="#Page_71">71</a>;
+</li><li>
+  management, <a href="#Page_74">74</a>
+</li></ul>
+</li><li>
+Mitscherlich, <a href="#Page_17">17</a>
+</li><li>
+Myristin, <a href="#Page_51">51</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+N</span>
+</li><li>&nbsp;
+</li><li>
+Neolithic times, <a href="#Page_1">1</a>
+</li><li>
+Nikolaiewa, <a href="#Page_95">95</a>
+</li><li>
+Nitrogenous constituents of milk, <a href="#Page_52">52</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+O</span>
+</li><li>&nbsp;
+</li><li>
+Ojr&agrave;n, <a href="#Page_106">106</a>
+</li><li>
+Olein, <a href="#Page_51">51</a>
+</li><li>
+Oxygala of Pliny, <a href="#Page_4">4</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+P</span>
+</li><li>&nbsp;
+</li><li>
+Paleolithic times, <a href="#Page_1">1</a>
+</li><li>
+Palmitin, <a href="#Page_51">51</a>
+</li><li>
+Pasteur, <a href="#Page_14">14</a>, <a href="#Page_78">78</a>
+</li><li>
+Pasteurisation, <a href="#Page_78">78</a>
+</li><li>
+Pelouze, <a href="#Page_17">17</a>
+</li><li>
+Pilaff of rice, <a href="#Page_5">5</a>
+</li><li>
+Pina, <a href="#Page_21">21</a>
+</li><li>
+Podowyssowski on keffir, <a href="#Page_87">87</a>
+</li><li>
+Preparation, of soured milk, <a href="#Page_81">81</a>;
+<ul><li>
+  in the house, <a href="#Page_125">125</a>;
+</li><li>
+  in the dairy, <a href="#Page_139">139</a>
+</li></ul>
+</li><li>
+Primary cooler, <a href="#Page_78">78</a>
+</li><li>
+Proteids, <a href="#Page_53">53</a>
+</li><li>
+Pyrenees, <a href="#Page_4">4</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+R</span>
+</li><li>&nbsp;
+</li><li>
+Reindeer's milk as soured milk, <a href="#Page_8">8</a>
+</li><li>
+Rubruquis, William de, <a href="#Page_19">19</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+S</span>
+</li><li>&nbsp;
+</li><li>
+<i>Saccharomyces cerevisse&aelig;</i>, <a href="#Page_90">90</a>
+</li><li>
+<i>Saccharomyces keffir</i>, <a href="#Page_32">32</a>, <a href="#Page_33">33</a>, <a href="#Page_91">91</a>, <a href="#Page_93">93</a>, <a href="#Page_94">94</a>
+</li><li>
+Sakwaska, <a href="#Page_88">88</a>
+</li><li>
+Sale of Food and Drugs Act, 1899, <a href="#Page_49">49</a>
+</li><li>
+Scheele, <a href="#Page_17">17</a>
+</li><li>
+Scholl on keffir, <a href="#Page_91">91</a>
+</li><li>
+Scythians, <a href="#Page_18">18</a>
+</li><li>
+Secondary cooler, <a href="#Page_79">79</a>
+</li><li>
+Shammar Bedouins, <a href="#Page_2">2</a>
+</li><li>
+Sheneena, <a href="#Page_2">2</a>
+</li><li>
+Skolotowski on keffir, <a href="#Page_86">86</a>
+</li><li>
+Smith, Professor Robertson, <a href="#Page_3">3</a>
+</li><li>
+Soured milk, in the house, <a href="#Page_125">125</a>;
+<ul><li>
+  in the dairy, <a href="#Page_139">139</a>;
+</li><li>
+  in health and disease, <a href="#Page_151">151</a>;
+</li><li>
+  from impure cultures, <a href="#Page_158">158</a>;
+</li><li>
+  use of, <a href="#Page_159">159</a>
+</li></ul>
+</li><li>
+Souring of milk, <a href="#Page_47">47</a>, <a href="#Page_54">54</a>
+</li><li>
+Specific gravity of milk, <a href="#Page_65">65</a>
+</li><li>
+Stearin, <a href="#Page_51">51</a>
+</li><li>
+Steriliser, <a href="#Page_148">148</a>
+</li><li>
+<i>Streptobacilli lebeni</i>, <a href="#Page_39">39</a>
+</li><li>
+<i>Streptobacillus lebenis</i>, <a href="#Page_111">111</a>
+</li><li>
+<i>Streptococcus a</i>, <a href="#Page_93">93</a>, <a href="#Page_94">94</a>
+</li><li>
+<i>Streptococcus acidi lactici</i>, <a href="#Page_95">95</a>, <a href="#Page_96">96</a>
+</li><li>
+<i>Streptococcus b</i>, <a href="#Page_93">93</a>, <a href="#Page_94">94</a>
+</li><li>
+<i>Streptococcus lacticus</i>, <a href="#Page_92">92</a>, <a href="#Page_93">93</a>, <a href="#Page_122">122</a>, <a href="#Page_124">124</a>
+</li><li>
+Sugar of milk, <a href="#Page_54">54</a>
+</li><li>
+Sugar preparations and the soured-milk bacillus, <a href="#Page_137">137</a>
+</li><li>
+Suter-Naef on Swiss koumiss, <a href="#Page_26">26</a>
+</li><li>
+Swedish whey cheese, <a href="#Page_60">60</a>
+</li><li>
+Swiss hard cheese, <a href="#Page_113">113</a>
+</li><li>
+Symptoms of disease, <a href="#Page_161">161</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+T</span>
+</li><li>&nbsp;
+</li><li>
+Temperature allowances when testing milk, tables of, <a href="#Page_66">66</a>
+</li><li>
+Town's dairy equipment, <a href="#Page_80">80</a>
+</li><li>
+Transmission of disease by milk, <a href="#Page_72">72</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+U</span>
+</li><li><p><span class='pagenum'><a name="Page_168" id="Page_168">168</a></span></p>
+</li><li>
+United Kingdom, milk supply of, <a href="#Page_69">69</a>
+</li><li>
+United States, milk industry of, <a href="#Page_71">71</a>
+</li><li>
+Urgoutnik, <a href="#Page_43">43</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+V</span>
+</li><li>&nbsp;
+</li><li>
+Van Leeuwenhoek, <a href="#Page_13">13</a>
+</li><li>
+Variation limits of milk, <a href="#Page_49">49</a>
+</li><li>
+Vedas, <a href="#Page_1">1</a>
+</li><li>
+"Veronelle" apparatus, <a href="#Page_132">132</a>
+</li><li>
+Vina, <a href="#Page_21">21</a>
+</li><li>
+Vinous fermentation, <a href="#Page_17">17</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+W</span>
+</li><li>&nbsp;
+</li><li>
+Willows Refrigerating Company's apparatus, <a href="#Page_144">144</a>, <a href="#Page_145">145</a>
+</li><li>
+Wilson on koumiss, <a href="#Page_23">23</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+Y</span>
+</li><li>&nbsp;
+</li><li>
+Yoghourt, <a href="#Page_9">9</a>, <a href="#Page_42">42</a>, <a href="#Page_46">46</a>, <a href="#Page_107">107</a>
+</li><li>
+Yoghourt bacillus, <a href="#Page_109">109</a>
+</li><li>&nbsp;
+</li><li><span style="margin-left: 6em;">
+Z</span>
+</li><li>&nbsp;
+</li><li>
+Zakvaska, <a href="#Page_42">42</a>
+</li></ul>
+<hr />
+<div class="box"><a name="putnam" id="putnam"></a>
+<h2>P&nbsp;u&nbsp;t&nbsp;n&nbsp;a&nbsp;m's<br />
+S&nbsp;c&nbsp;i&nbsp;e&nbsp;n&nbsp;c&nbsp;e&nbsp;&nbsp;S&nbsp;e&nbsp;r&nbsp;i&nbsp;e&nbsp;s</h2>
+
+
+<p class="indent">1. <b>The Study of Man.</b> By <span class="smcap">A. C. Haddon</span>.</p>
+
+<p class="indent">2. <b>The Groundwork of Science.</b> By <span class="smcap">St. George Mivart</span>.</p>
+
+<p class="indent">3. <b>Rivers of North America.</b> By <span class="smcap">Israel C. Russell</span>.</p>
+
+<p class="indent">4. <b>Earth Sculpture, or; The Origin of Land Forms.</b> By <span class="smcap">James Geikie</span>.</p>
+
+<p class="indent">5. <b>Volcanoes; Their Structure and Significance.</b> By <span class="smcap">T. G. Bonney</span>.</p>
+
+<p class="indent">6. <b>Bacteria.</b> By <span class="smcap">George Newman</span>.</p>
+
+<p class="indent">7. <b>A Book of Whales.</b> By <span class="smcap">F. E. Beddard</span>.</p>
+
+<p class="indent">8. <b>Comparative Physiology of the Brain, etc.</b> By <span class="smcap">Jacques Loeb</span>.</p>
+
+<p class="indent">9. <b>The Stars.</b> By <span class="smcap">Simon Newcomb</span>.</p>
+
+<p class="indent">10. <b>The Basis of Social Relations.</b> By <span class="smcap">Daniel G. Brinton</span>.</p>
+
+<p class="indent">11. <b>Experiments on Animals.</b> By <span class="smcap">Stephen Paget</span>.</p>
+
+<p class="indent">12. <b>Infection and Immunity.</b> By <span class="smcap">George M. Sternberg</span>.</p>
+
+<p class="indent">13. <b>Fatigue.</b> By <span class="smcap">A. Mosso</span>.</p>
+
+<p class="indent">14. <b>Earthquakes.</b> By <span class="smcap">Clarence E. Dutton</span>.</p>
+
+<p class="indent">15. <b>The Nature of Man.</b> By <span class="smcap">&Eacute;lie Metchnikoff</span>.</p>
+
+<p class="indent">16. <b>Nervous and Mental Hygiene in Health and Disease.</b> By <span class="smcap">August Forel</span>.</p>
+
+<p class="indent">17. <b>The Prolongation of Life.</b> By <span class="smcap">&Eacute;lie Metchnikoff</span>.</p>
+
+<p class="indent">18. <b>The Solar System.</b> By <span class="smcap">Charles Lane Poor</span>.</p>
+
+<p class="indent">19. <b>Heredity.</b> By <span class="smcap">J. Arthur Thompson,</span> M.A.</p>
+
+<p class="indent">20. <b>Climate.</b> By <span class="smcap">Robert DeCourcy Ward</span>.</p>
+
+<p class="indent">21. <b>Age, Growth, and Death.</b> By <span class="smcap">Charles S. Minot</span>.</p>
+
+<p class="indent">22. <b>The Interpretation of Nature.</b> By <span class="smcap">C. Lloyd Morgan</span>.</p>
+
+<p class="indent">23. <b>Mosquito Life.</b> By <span class="smcap">Evelyn Groesbeeck Mitchell</span>.</p>
+
+<p class="indent">24. <b>Thinking, Feeling, Doing.</b> By <span class="smcap">E. W. Scripture</span>.</p>
+
+<p class="indent">25. <b>The World's Gold.</b> By <span class="smcap">L. de Launay</span>.</p>
+
+<p class="indent">26. <b>The Interpretation of Radium.</b> By <span class="smcap">F. Soddy</span>.</p>
+
+<p class="indent">27. <b>Criminal Man.</b> By <span class="smcap">Cesare Lombroso</span>.</p>
+
+<p class="indent">28. <b>The Origin of Life.</b> By <span class="smcap">H. Charlton Bastian</span>.</p>
+
+<p class="indent">29. <b>The Bacillus of Long Life.</b> By <span class="smcap">Loudon M. Douglas</span>.</p>
+
+<hr class="a" />
+
+<p class="center2"><i>For list of works in preparation see end of this volume</i>
+</p>
+</div>
+
+<h4>
+<i>A Selection from the<br />
+Catalogue of</i></h4>
+<h3>
+G. P. PUTNAM'S SONS</h3>
+
+<div class="figcenter" style="width: 96px;">
+<img src="images/ornament.jpg" width="96" height="69" alt=
+"ornament"
+title="" /></div>
+
+<h6>
+Complete Catalogue sent<br />
+on application</h6>
+
+<h3>Putnam's<br />
+Science Series</h3>
+
+
+<p class="indent"><b>1.&mdash;The Study of Man.</b> By Professor <span class="smcap">A. C. Haddon</span>, M.A., D.Sc.,
+M.R.I.A. Fully illustrated. 8&deg;, net $2.00.</p>
+
+<p class="small">"A timely and useful volume.... The author wields a pleasing pen and knows
+how to make the subject attractive.... The work is calculated to spread among its
+readers an attraction to the science of anthropology. The author's observations are
+exceedingly genuine and his descriptions are vivid."&mdash;<i>London Athen&aelig;um.</i></p>
+
+
+<p class="indent"><b>2.&mdash;The Groundwork of Science.</b> A Study of Epistemology. By
+<span class="smcap">St. George Mivart</span>, F.R.S. 8&deg;, net $1.75.</p>
+
+<p class="small">"The book is cleverly written and is one of the best works of its kind ever put before
+the public. It will be interesting to all readers, and especially to those interested in the
+study of science."&mdash;<i>New Haven Leader.</i></p>
+
+
+<p class="indent"><b>3.&mdash;Rivers of North America.</b> A Reading Lesson for Students of Geography
+and Geology. By <span class="smcap">Israel C. Russell</span>, Professor of Geology,
+University of Michigan, author of "Lakes of North America," "Glaciers
+of North America," "Volcanoes of North America," etc. Fully
+illustrated. 8&deg;, net $2.00.</p>
+
+<p class="small">"There has not been in the last few years until the present book any authoritative,
+broad r&eacute;sum&eacute; on the subject, modified and deepened as it has been by modern research
+and reflection, which is couched in language suitable for the multitude.... The text
+is as entertaining as it is instructive."&mdash;<i>Boston Transcript.</i></p>
+
+
+<p class="indent"><b>4.&mdash;Earth Sculpture; or, The Origin of Land-Forms.</b> By <span class="smcap">James
+Geikie</span>, LL.D., D.C.L., F.R.S., etc., Murchison Professor of Geology
+and Mineralogy in the University of Edinburgh; author of "The
+Great Ice Age," etc. Fully illustrated. 8&deg;, net $2.00.</p>
+
+<p class="small">"This volume is the best popular and yet scientific treatment we know of the origin
+and development of land-forms, and we immediately adopted it as the best available
+text-book for a college course in physiography.... The book is full of life and vigor,
+and shows the sympathetic touch of a man deeply in love with nature."&mdash;<i>Science.</i></p>
+
+
+<p class="indent"><b>5.&mdash;Volcanoes.</b> By <span class="smcap">T. G. Bonney</span>, F.R.S., University College, London.
+Fully illustrated. 8&deg;, net $2.00.</p>
+
+<p class="small">"It is not only a fine piece of work from a scientific point of view, but it is uncommonly
+attractive to the general reader, and is likely to have a larger sale than most books
+of its class."&mdash;<i>Springfield Republican.</i></p>
+
+
+<p class="indent"><b>6.&mdash;Bacteria</b>: Especially as they are related to the economy of nature, to
+industrial processes, and to the public health. By <span class="smcap">George Newman,</span>
+M.D., F.R.S. (Edin.), D.P.H. (Camb.), etc., Demonstrator of Bacteriology
+in King's College, London. With 24 micro-photographs of
+actual organisms and over 70 other illustrations. 8&deg;, net $2.00.</p>
+
+<p class="small">"Dr. Newman's discussions of bacteria and disease, of immunity, of antitoxins, and
+of methods of disinfection, are illuminating, and are to be commended to all seeking information
+on these points. Any discussion of bacteria will seem technical to the uninitiated,
+but all such will find in this book popular treatment and scientific accuracy happily
+combined."&mdash;<i>The Dial.</i></p>
+
+<p class="indent"><b>7.&mdash;A Book of Whales.</b> By <span class="smcap">F. E. Beddard</span>, M.A., F.R.S. Illustrated
+8&deg;. $2.00.</p>
+
+<p class="small">"Mr. Beddard has done well to devote a whole volume to whales. They are worthy
+of the biographer who has now well grouped and described these creatures. The general
+reader will not find the volume too technical, nor has the author failed in his attempt to
+produce a book that shall be acceptable to the zoologist and the naturalist."&mdash;<i>N. Y. Times.</i></p>
+
+
+<p class="indent"><b>8.&mdash;Comparative Physiology of the Brain and Comparative Psychology.</b>
+With special reference to the Invertebrates. By <span class="smcap">Jacques
+Loeb</span>, M.D., Professor of Physiology in the University of Chicago.
+Illustrated. 8&deg;. $1.75.</p>
+
+<p class="small">"No student of this most interesting phase of the problems of life can afford to remain
+in ignorance of the wide range of facts and the suggestive series of interpretations which
+Professor Loeb has brought together in this volume."&mdash;<span class="smcap">Joseph Jastrow</span>, in the <i>Chicago
+Dial.</i></p>
+
+
+<p class="indent"><b>9.&mdash;The Stars.</b> By Professor <span class="smcap">Simon Newcomb</span>, U.S.N., Nautical Almanac
+Office, and Johns Hopkins University. 8&deg;. Illustrated. Net.
+$2.00. (By mail, $2.00.)</p>
+
+<p class="small">"The work is a thoroughly scientific treatise on stars. The name of the author is
+sufficient guarantee of scholarly and accurate work."&mdash;<i>Scientific American.</i></p>
+
+
+<p class="indent"><b>10.&mdash;The Basis of Social Relations.</b> A Study in Ethnic Psychology. By
+<span class="smcap">Daniel G. Brinton</span>, A.M., M.D., LL.D., Sc.D., Late Professor of
+American Arch&aelig;ology and Linguistics in the University of Pennsylvania;
+Author of "History of Primitive Religions," "Races and
+Peoples," "The American Race," etc. Edited by <span class="smcap">Livingston Farrand</span>,
+Columbia University. 8&deg;. Net, $1.50 (By mail, $1.60.)</p>
+
+<p class="small">"Professor Brinton has shown in this volume an intimate and appreciative knowledge
+of all the important anthropological theories. No one seems to have been better acquainted
+with the very great body of facts represented by these sciences."&mdash;<i>Am. Journal of
+Sociology.</i></p>
+
+<p class="indent"><b>11.&mdash;Experiments on Animals.</b> By <span class="smcap">Stephen Paget</span>. With an Introduction
+by Lord Lister. Illustrated. 8&deg;. Net, $2.00. (By mail, $2.20.)</p>
+
+<p class="small">"To a large class of readers this presentation will be attractive, since it gives to them
+in a nut-shell the meat of a hundred scientific dissertations in current periodical literature.
+The volume has the authoritative sanction of Lord Lister."&mdash;<i>Boston Transcript.</i></p>
+
+
+<p class="indent"><b>12.&mdash;Infection and Immunity.</b> With Special Reference to the Prevention
+of Infectious Diseases. By <span class="smcap">George M. Sternberg</span>, M.D., LL.D.,
+Surgeon-General U. S. Army (Retired). Illustrated. 8&deg;. Net, $1.75
+(By mail, $1.90.)</p>
+
+<p class="small">"A distinct public service by an eminent authority. This admirable little work should
+be a part of the prescribed reading of the head of every institution in which children or
+youths are gathered. Conspicuously useful."&mdash;<i>N. Y. Times.</i></p>
+
+
+<p class="indent"><b>13.&mdash;Fatigue.</b> By <span class="smcap">A. Mosso</span>, Professor of Physiology in the University of
+Turin. Translated by <span class="smcap">Margaret Drummond</span>, M.A., and <span class="smcap">W. B.
+Drummond</span>, M.B., C.M., F.R.C.P.E., extra Physician, Royal Hospital
+for Sick Children, Edinburgh; Author of "The Child. His Nature
+and Nurture." Illustrated. 8&deg;. Net, $1.50.</p>
+
+<p class="small">"A book for the student and for the instructor, full of interest, also for the intelligent
+general reader. The subject constitutes one of the most fascinating chapters in the history
+of medical science and of philosophical research."&mdash;<i>Yorkshire Post.</i></p>
+<p class="indent"><b>14.&mdash;Earthquakes.</b> In the Light of the New Seismology By <span class="smcap">Clarence
+E. Dutton</span>, Major, U. S. A. Illustrated 8&deg;. Net, $2.00. (By
+mail, $2.20.)</p>
+
+<p class="small">"The book summarizes the results of the men who have accomplished the great
+things in their pursuit of seismological knowledge. It is abundantly illustrated and it
+fills a place unique in the literature of modern science"&mdash;<i>Chicago Tribune.</i></p>
+
+
+<p class="indent"><b>15.&mdash;The Nature of Man.</b> Studies in Optimistic Philosophy. By <span class="smcap">&Eacute;lie
+Metchnikoff</span>, Professor at the Pasteur Institute. Translation and
+introduction by <span class="smcap">P. Chambers Mitchell</span>, M.A., D.Sc. Oxon. Illustrated.
+8&deg;. Net, $1.50.</p>
+
+<p class="small">"A book to be set side by side with Huxley's Essays, whose spirit it carries a step
+further on the long road towards its goal"&mdash;<i>Mail and Express.</i></p>
+
+
+<p class="indent"><b>16.&mdash;The Hygiene of Nerves and Mind in Health and Disease.</b> By
+<span class="smcap">August Forel</span>, M.D., formerly Professor of Psychiatry in the University
+of Zurich. Authorized Translation. 8&deg;. Net, $2.00. (By
+mail, $2.20.)</p>
+
+<p class="small">A comprehensive and concise summary of the results of science in its chosen field.
+Its authorship is a guarantee that the statements made are authoritative as far as the
+statement of an individual can be so regarded.</p>
+
+
+<p class="indent"><b>17.&mdash;The Prolongation of Life.</b> Optimistic Essays. By <span class="smcap">&Eacute;lie Metchnikoff</span>,
+Sub-Director of the Pasteur Institute. Author of "The
+Nature of Man." etc.   8&deg;.   Illustrated.   Net, $2.50.   (By mail, $2.70.)
+Popular Edition. With an introduction by Prof. <span class="smcap">Charles S. Minot</span>.
+Net, $1.75.</p>
+
+<p class="small">In his new work Professor Metchnikoff expounds at greater length, in the light of
+additional knowledge gained in the last few years, his main thesis that human life is not
+only unnaturally short but unnaturally burdened with physical and mental disabilities.
+He analyzes the causes of these disharmonies and explains his reasons for hoping that
+they may be counteracted by a rational hygiene.</p>
+
+
+<p class="indent"><b>18.&mdash;The Solar System.</b> A Study of Recent Observations. By Prof.
+<span class="smcap">Charles Lane Poor</span>, Professor of Astronomy in Columbia University.
+8&deg;. Illustrated. Net, $2.00.</p>
+
+<p class="small">The subject is presented in untechnical language and without the use of mathematics.
+Professor Poor shows by what steps the precise knowledge of to day has been reached and
+explains the marvellous results of modern methods and modern observations.</p>
+
+
+<p class="indent"><b>19.&mdash;Climate&mdash;Considered Especially in Relation to Man.</b> By <span class="smcap">Robert
+DeCourcy Ward</span>, Assistant Professor of Climatology in Harvard
+University. 8&deg;. Illustrated. Net, $2.00.</p>
+
+<p class="small">This volume is intended for persons who have not had special training in the technicalities
+of climatology. Climate covers a wholly different field from that included in
+the meteorological text-books It handles broad questions of climate in a way which has
+not been attempted in a single volume The needs of the teacher and student have been
+kept constantly in mind.</p>
+
+
+<p class="indent"><b>20.&mdash;Heredity.</b> By <span class="smcap">J. Arthur Thomson</span>, M.A., Professor of Natural
+History in the University of Aberdeen; Author of "The Science of
+Life," etc. 8&deg;. Illustrated. Net, $3.50.</p>
+
+<p class="small">The aim of this work is to expound, in a simple manner, the facts of heredity and
+inheritance as at present known, the general conclusions which have been securely
+established, and the more important theories which have been formulated.</p>
+
+
+<p class="indent"><b>21.&mdash;Age, Growth, and Death.</b> By <span class="smcap">Charles S. Minot</span>, James Stillman
+Professor of Comparative Anatomy in Harvard University,
+President of the Boston Society of Natural History, and Author of
+"Human Embryology," "A Laboratory Text-book of Embryology,"
+etc. 8&deg;. Illustrated.</p>
+
+<p class="small">This volume deals with some of the fundamental problems of biology, and presents
+series of views (the results of nearly thirty years of study), which the author has
+correlated for the first time in systematic form.</p>
+<p class="indent"><b>22.&mdash;The Interpretation of Nature.</b> By <span class="smcap">C. Lloyd Morgan</span>, LL.D.,
+F.R.S. Crown 8vo. Net, $1.25.</p>
+
+<p class="small">Dr Morgan seeks to prove that a belief in purpose as the causal reality of which
+nature is an expression is not inconsistent with a full and whole-hearted acceptance of
+the explanations of naturalism.</p>
+
+
+<p class="indent"><b>23.&mdash;Mosquito Life.</b> The Habits and Life Cycles of the Known Mosquitoes
+of the United States; Methods for their Control; and Keys for
+Easy Identification of the Species in their Various Stages. An account
+based on the investigation of the late James William Dupree, Surgeon-General
+of Louisiana, and upon the original observations by the Writer.
+By <span class="smcap">Evelyn Groesbeeck Mitchell</span>, A.B., M.S. With 64 Illustrations.
+Crown 8vo. Net, $2.00.</p>
+
+<p class="small">This volume has been designed to meet the demand of the constantly increasing
+number of students for a work presenting in compact form the essential facts so far made
+known by scientific investigation in regard to the different phases of this, as is now conceded,
+important and highly interesting subject. While aiming to keep within reasonable
+bounds, that it may be used for work in the field and in the laboratory, no portion
+of the work has been slighted, or fundamental information omitted, in the endeavor to
+carry this plan into effect.</p>
+
+
+<p class="indent"><b>24.&mdash;Thinking, Feeling, Doing.</b> An Introduction to Mental Science.
+By <span class="smcap">E. W. Scripture</span>, Ph.D., M.D., Assistant Neurologist Columbia
+University, formerly Director of the Psychological Laboratory at Yale
+University. 189 Illustrations. 2d Edition, Revised and Enlarged.
+Crown 8vo. Net, $1.75.</p>
+
+<p class="small">"The chapters on Time and Action, Reaction Time, Thinking Time, Rhythmic
+Action, and Power and Will are most interesting. This book should be carefully read
+by every one who desires to be familiar with the advances made in the study of the
+mind, which advances, in the last twenty-five years, have been quite as striking and
+epoch-making as the strides made in the more material lines of knowledge."&mdash;<i>Jour.
+Amer. Med. Ass'n.</i>, Feb. 22, 1908.</p>
+
+
+<p class="indent"><b>25.&mdash;The World's Gold.</b> By <span class="smcap">L. de Launay</span>, Professor at the &Eacute;cole
+Superieure des Mines.    Translated by Orlando Cyprian Williams.
+With an Introduction by Charles A. Conant, author of "History of
+Modern Banks of Issue," etc. Crown 8vo. Net, $1.75.</p>
+
+<p class="small">M. de Launay is a professor of considerable repute not only in France, but among
+scientists throughout the world. In this work he traces the various uses and phases
+of gold; first, its geology; secondly, its extraction; thirdly, its economic value.</p>
+
+
+<p class="indent"><b>26.&mdash;The Interpretation of Radium.</b> By <span class="smcap">Frederick Soddy</span>, Lecturer
+in Physical Chemistry in the University of Glasgow. Crown 8vo.
+With Diagrams. Net, $1.75.</p>
+
+<p class="small">As the application of the present day interpretation of Radium (that it is an element
+undergoing spontaneous disintegration) is not confined to the physical sciences, but has
+a wide and general bearing upon our whole outlook on Nature, Mr. Soddy has presented
+the subject in non-technical language, so that the ideas involved are within reach of the
+lay reader. No effort has been spared to get to the root of the matter and to secure
+accuracy, so that the book should prove serviceable to other fields of science and investigation,
+as well as to the general public.</p>
+
+
+<p class="indent"><b>27.&mdash;Criminal Man.</b> According to the Classification of <span class="smcap">Cesare Lombroso</span>.
+Briefly Summarized by his Daughter, Gina Lombroso Ferrero.
+With 36 Illustrations and a Bibliography of Lombroso's Publications
+on the Subject. Crown 8vo. Net, $2.00.</p>
+
+<p class="small">Signora Guglielmo Ferrero's r&eacute;sum&eacute; of her father's work on criminal anthropology is
+specially dedicated to all those whose office it is to correct, reform, and punish the criminal,
+with a view to diminishing the injury caused to society by his anti-social acts; also
+to superintendents, teachers, and those engaged in rescuing orphans and children of
+vicious habits, as a guide in checking the development of evil germs and eliminating
+incorrigible subjects whose example is a source of corruption to others.<br /><br /></p>
+
+
+
+<div class="box">
+<h6>
+The most valuable production since Darwin's "Origin
+of Species."</h6>
+
+<hr style='width: 90%;' />
+<h2><b>
+The Nature of Man</b></h2>
+
+<h4><b><i>Studies in Optimistic Philosophy</i></b></h4>
+
+<h3><b>By &Eacute;lie Metchnikoff</b><br />
+
+<small>Sub-Director of the Pasteur Institute, Paris</small></h3>
+
+<h5>Translated with an Introduction by<br />
+
+<b>P. Chambers Mitchell</b><br />
+
+Secretary of the Zo&ouml;logical Society</h5>
+
+<hr />
+
+<h6>Octavo. Illustrated. Popular Edition. $1.50 net. By mail, $1.65</h6>
+
+<hr />
+
+<p>It is not often that a scientific book may be read with
+ease, profit, and pleasure by the general reader, so that
+M. Metchnikoff's book comes in the nature of an agreeable
+surprise. It is marked by a refreshing <i>na&iuml;vet&eacute;</i> and a large
+simplicity which are characteristically Russian. The scientific
+importance of this work is so great that it is spoken of
+in England as the most valuable production since Darwin's
+<i>Origin of Species</i>.</p>
+
+<hr />
+
+<h5>
+Opinions of the Press</h5>
+
+
+<p class="small">"An extremely interesting and typical book.... With a distinguished
+frankness, M. Metchnikoff defines his attitude to our universal
+prepossessions. It is his theory that the infirmities of age are to be
+overcome. If there be ground for this conception, humanity is to be
+profoundly changed and what we call life now, will be the childhood
+and youth of that longer and larger life."&mdash;<span class="smcap">H. G. Wells</span>, in <i>London
+Speaker</i>.</p>
+
+<p class="small">"Undoubtedly a great book (in some quarters it has been hailed as
+the greatest since Darwin's famous message to the world) and should
+be read by all intelligent men and women."&mdash;<i>The Nation.</i></p>
+
+<p class="small">"A book to be set side by side with Huxley's Essays, whose spirit it
+carries a step further on the long road towards its goal."&mdash;<i>Mail and
+Express.</i></p>
+
+<hr style='width: 90%;' />
+
+<h4><b>
+New York&mdash;G. P. Putnam's Sons&mdash;London</b></h4>
+</div>
+<p><br /></p>
+<div class="box">
+
+<h6>"<i>Remarkable for its simple language and clear
+style.... Bears the stamp of a production of
+an erudite scientist and a deep thinker.</i>"&mdash;Science.</h6>
+
+<hr style='width: 90%;' />
+
+<h2><b>
+The Prolongation of<br />
+Life</b></h2>
+
+<h4><small><b>
+Optimistic Essays</b><br />
+
+<b><i>By</i> &Eacute;lie Metchnikoff</b><br />
+<br />
+<b><i>Author of "The Nature of Man," etc.</i></b><br />
+<br />
+<small><i>8vo. Illustrated Popular Edition. $1.75 net<br />
+By mail, $1.90</i></small></small>
+</h4>
+
+<p>M. &Eacute;lie Metchnikoff is one of those rare scientists who
+have found a way to lay hold of and present to the world in
+untechnical phraseology, intelligible to the lay mind, such
+results of his researches as are of universal interest and go
+straight home to the bosoms and business of intelligent men.
+<i>The Nature of Man</i>, by the same author, was one of the most
+fascinating books, at once popular, and scientific, which have
+appeared for decades. The book here in question will stand
+beside it as a worthy companion volume. It is satisfactory
+to report that, absorbed as Metchnikoff is in "material"
+problems, and deep as he is in the mysteries of the physical
+universe, these essays show him to be an optimist who speaks
+with no uncertain voice.</p>
+
+<p>A great deal of attention is given in <i>The Prolongation of
+Human Life</i> to the subject of old age and its causes, with
+scientific observations of special cases among human beings
+and the lower animals. The author suggests means of prolonging
+life and health, while contemplating natural death
+with serenity, and finding that agreeable sensations accompany
+its approach. Beyond a certain point it seems to him a disadvantage
+to prolong life. Passing on from these mortuary
+lucubrations, the essays concern themselves with psychological
+matters, with optimism and pessimism and in general with
+questions of science and morals. The temperaments of certain
+great men are analyzed in studies that have for their subjects
+respectively Byron, Leopardi, Schopenhauer, and Goethe. In
+the preface the author says that he has avoided, as far as
+possible, repeating points which have been sufficiently treated
+in <i>The Nature of Man</i>.</p></div>
+
+<hr style='width: 90%;' />
+
+<h4><b>
+G. P. PUTNAM'S SONS<br />
+<br />
+NEW YORK&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;LONDON<br />
+</b></h4>
+
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
+End of Project Gutenberg's The Bacillus of Long Life, by Loudon Douglas
+
+*** END OF THIS PROJECT GUTENBERG EBOOK THE BACILLUS OF LONG LIFE ***
+
+***** This file should be named 31691-h.htm or 31691-h.zip *****
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+</body>
+</html>
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@@ -0,0 +1,5661 @@
+The Project Gutenberg EBook of The Bacillus of Long Life, by Loudon Douglas
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: The Bacillus of Long Life
+       a manual of the preparation and souring of milk for dietary
+       purposes, together with and historical account of the use
+       of fermente
+
+Author: Loudon Douglas
+
+Release Date: March 18, 2010 [EBook #31691]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE BACILLUS OF LONG LIFE ***
+
+
+
+
+Produced by Peter Vachuska, Turgut Dincer, Chuck Greif and
+the Online Distributed Proofreading Team at
+https://www.pgdp.net
+
+
+
+
+
+
+
+  +---------------------------------------------------------+
+  | Transcriber's note:                                     |
+  |                                                         |
+  | Words in bold characters are enclosed within "+" signs. |
+  | The list of Putnam Science Series has been moved to the |
+  | advertisement section at the end of the book. The UTF-8 |
+  | version of the text file will require a Unicode capable |
+  | text reader to display a few Greek characters and "oe"  |
+  | ligatures which occur in the book.                      |
+  +---------------------------------------------------------+
+
+
+
+
+  [Illustration: THE OLDEST WOMAN IN THE WORLD AND HER SON
+
+  Baba Vasilka is 126 years old, and her son Tudor is 101.
+  They are peasants, and have lived all their lives in a
+  little village in Bulgaria. They are typical examples of
+  people who live to a great age by the use of soured milk,
+  as it has been their principal food all their lives.]
+
+
+                         The
+                Bacillus of Long Life
+
+  A Manual of the Preparation and Souring of Milk for
+    Dietary Purposes, Together with an Historical
+     Account of the Use of Fermented Milks, from
+        the Earliest Times to the Present Day,
+         and Their Wonderful Effect in the
+           Prolonging of Human Existence
+
+                         By
+             Loudon M. Douglas, F.R.S.E.
+
+               _With 62 Illustrations_
+
+
+                 G. P. Putnam's Sons
+                 New York and London
+               The Knickerbocker Press
+                        1911
+
+
+                  _Revised Edition_
+
+
+                    COPYRIGHT, 1911
+                         BY
+                  G. P. PUTNAM'S SONS
+
+
+             The Knickerbocker Press, New York
+
+
+
+
+PREFACE
+
+
+This book has been designed with a view to meet an extensive demand for
+definite data on the subject of Soured Milks. The author has had this
+matter brought before him, times without number, by those inquiring for
+authentic information on the subject, and he has therefore considered it
+desirable to gather together such information as is available in
+connection with ancient and modern practice. He has endeavoured to
+present this to the reader in concise form.
+
+The author is indebted to many friends for their assistance in getting
+the book together, and would specially mention Dr. H. B. Hutchinson,
+Bacteriologist, Rothamsted Experimental Station, for assistance in
+connection with the bacteriology of fermented milks; Mr. Thomas Douglas,
+of Wimbledon, who has assisted with the chemistry of the subject; Mr. S.
+Javrilovitch, of Belgrade, Servia, for local information and
+illustrations; Dr. Otokar Laxa, Bacteriologist, of Prague, Bohemia, for
+general assistance; the editor of _Bacteriotherapy_, New York, U.S.A.,
+for the use of the group of illustrations 30-44; the publishers of the
+_Centralblatt fuer Bakteriologie_, Jena, for the group of illustrations
+14-29; and many others, some of whom are referred to in the text.
+
+
+  CONTENTS
+
+
+  CHAPTER                                                    PAGE
+
+     I.--INTRODUCTORY--HISTORICAL                               1
+
+    II.--FERMENTED MILKS                                       15
+
+   III.--THE CHEMISTRY OF MILK                                 47
+
+    IV.--HANDLING OF MILK                                      68
+
+     V.--THE BACTERIOLOGY OF FERMENTED OR SOURED MILK          84
+
+    VI.--THE PREPARATION OF SOURED MILK IN THE HOUSE          125
+
+   VII.--THE PREPARATION OF SOURED MILK IN THE DAIRY          139
+
+  VIII.--SOURED MILK IN HEALTH AND DISEASE                    151
+
+         INDEX                                                165
+
+
+
+
+ILLUSTRATIONS
+
+
+  FIG.                                                       PAGE
+
+       THE OLDEST WOMAN IN THE WORLD AND HER SON   _Frontispiece_
+
+       THE PASS OF BUKOVA                                       2
+
+       KABYLES SOURING MILK                                     4
+
+       THE HANDLING OF MILK IN THE PYRENEES                     8
+
+       THE CONSTITUENTS OF MILK                                48
+
+   1.--MICRO-PHOTOGRAPH OF A DROP OF WHOLE MILK                58
+
+   2.--MICRO-PHOTOGRAPH OF SEPARATED MILK                      58
+
+   3.--MICRO-PHOTOGRAPH OF CREAM                               58
+
+   4.--PHOTOGRAPH OF TWO PETRI DISHES, WHICH HAVE BEEN
+         INOCULATED WITH ORDINARY MILK                         60
+
+   5.--THE CREAMOMETER                                         62
+
+   6.--TESTING-GLASS FOR EXTRANEOUS MATTER IN MILK             62
+
+   7.--LACTOMETER AND TEST-GLASS                               64
+
+   8.--PASTEURISER                                             78
+
+   9.--CONTINUOUS APPARATUS FOR THE PRODUCTION OF LARGE
+         QUANTITIES OF SOURED MILK                             82
+
+  10.--A MILK-FILLING APPARATUS                                90
+
+  11.--SECTION THROUGH A KEPHIR GRAIN                          94
+
+  12.--_Streptococcus lacticus_ (GROTENFELDT) GROWING ON
+          LACTOSE-AGAR, STAINED BY GRAM'S METHOD               96
+
+  13.--PHOTO-MICROGRAPH OF PREPARATION FROM ARMENIAN SOURED
+         MILK (MATZOON)                                       106
+
+  14.--GRANULE BACILLUS FROM YOGHOURT. SHREDDED PREPARATION
+         OF A FRESH SKIM-MILK CULTURE                         110
+
+  15.--GRANULE BACILLUS FROM YOGHOURT, CULTIVATED AFTER
+         THE USUAL AGAR METHOD                                110
+
+  16.--GRANULE BACILLUS FROM YOGHOURT. AGAR MILK SUGAR
+         CULTURE                                              110
+
+  17.--_Bacteria W._ FROM MILK, CULTIVATED TWENTY-FOUR
+          HOURS                                               110
+
+  18.--AGAR MILK SUGAR CULTURE. FROM THE ORIGINAL BULGARIAN
+         YOGHOURT                                             112
+
+  19.--AGAR MILK SUGAR CULTURE. SURFACE COLONY OF GRANULE
+         BACILLUS FROM CALF'S STOMACH                         112
+
+  20.--AGAR MILK SUGAR CULTURE. DEEP-LYING COLONY
+         OF GRANULE BACILLUS FROM CALF'S STOMACH              112
+
+  21.--AGAR MILK SUGAR. COLONY OF _Bacterium W._ FROM
+         YOGHOURT                                             112
+
+  22.--TWO COLONIES OF _Bacillus Acidophilus_ FROM CALVES'
+         MANURE                                               114
+
+  23.--BEER-WORT GELATINE                                     114
+
+  24.--SHREDDED PREPARATION OF BULGARIAN ORIGINAL YOGHOURT    114
+
+  25.--GRANULE BACILLUS FROM YOGHOURT. CULTIVATED IN SKIM
+         MILK IN TWENTY-FOUR HOURS                            114
+
+  26.--_Bacteria W._, AGAR MILK SUGAR CULTURE                 116
+
+  27.--_Bacteria acidophilus_ FROM CALVES' MANURE             116
+
+  28.--MUCUS FROM CALF'S STOMACH INOCULATED INTO MILK AFTER
+         EIGHT TRANSFERRINGS                                  116
+
+  29.--DIPLOSTREPTOCOCCUS FROM YOGHOURT. PURE CULTURE IN
+         SKIM MILK                                            116
+
+  30.--PHOTO-MICROGRAPH OF PREPARATION MADE FROM YOGHOURT,
+         SHOWING YEAST CELLS                                  118
+
+  31.--PHOTO-MICROGRAPH OF SMEAR FROM GREEK CURDLED MILK
+         CALLED "GIAOURTI"                                    118
+
+  32.--PHOTO-MICROGRAPH OF SOURED MILK INOCULATED WITH
+         A TABLET CONTAINING VIABLE AND PURE CULTURES OF
+        _Bacillus bulgaricus_                                 120
+
+  33.--PHOTO-MICROGRAPH OF MILK INOCULATED WITH A FERMENT
+         TABLE IN WHICH _Bacillus bulgaricus_ IS NO LONGER
+         VIABLE                                               120
+
+  34.--PHOTO-MICROGRAPH OF SMEAR OF CULTURE OF _Bacillus
+         bulgaricus_                                          122
+
+  35.--_Bacillus bulgaricus_, SHOWING THE CULTURES
+          IN ENGLISH COW'S MILK                               124
+
+  36.--PHOTO-MICROGRAPH OF PURE CULTURE OF _Bacillus
+         bulgaricus_                                          124
+
+  37.--PHOTO-MICROGRAPH OF SMEAR OF COMBINED CULTURE
+         OF _Bacillus bulgaricus_ AND _Bacteria
+         paralacticus_                                        124
+
+  38.--PHOTO-MICROGRAPH OF SMEAR OF ONE-MONTH CULTURE
+         OF _Bacillus bulgaricus_                             126
+
+  39.--PHOTO-MICROGRAPH OF CULTURE OF _Bacillus bulgaricus_
+         IN MALT                                              126
+
+  40.--PHOTO-MICROGRAPH OF SMEAR FROM MILK THAT HAD BEEN
+         ALLOWED TO SOUR SPONTANEOUSLY                        126
+
+  41.--PHOTOGRAPH OF AGAR CULTURE, INOCULATED WITH A LACTIC
+         POWDER                                               128
+
+  42.--PHOTOGRAPH OF TEST-TUBES OF STERILE MILK, INOCULATED
+         WITH A TABLET PREPARATION SAID TO CONTAIN PURE
+         CULTURES                                             128
+
+  43.--PHOTOGRAPH OF TEST-TUBES OF STERILE MILK, EACH TUBE
+         HAVING BEEN INOCULATED WITH A TABLET OF A
+         PREPARATION SAID TO CONTAIN PURE CULTURES            128
+
+  44.--PHOTOGRAPH OF TEST-TUBES OF STERILE MILK INOCULATED
+         WITH A TABLET OF "LACTOBACILLINE"                    130
+
+  45.--APPARATUS OF "LE FERMENT" CO.                          129
+
+  46.--SOURED MILK APPARATUS OF THE MAYA BULGARE COMPANY,
+         LIMITED                                              130
+
+  47.--LACTIC FERMENTS, LIMITED, APPARATUS                    131
+
+  48.--MESSRS. ALLEN & HANBURY'S SOURED MILK APPARATUS        132
+
+  49.--VIRONELLE APPARATUS FOR SOURING MILK, MADE BY
+         MESSRS. CLAY, PAGET & COMPANY, LIMITED               132
+
+  50.--"LACTOBATOR" MADE BY MESSRS. CHARLES HEARSON & CO.,
+          LIMITED                                             140
+
+  51.--MESSRS. HEARSON & COMPANY'S "LACTOBATOR"               142
+
+  52.--EDGAR'S "LACTOGENERATOR," SOLD BY THE DAIRY SUPPLY
+         CO., LIMITED                                         143
+
+  53.--APPARATUS OF THE WILLOWS REFRIGERATING CO., LIMITED    144
+
+  54.--"LACTO" APPARATUS OF THE DAIRY OUTFIT CO., LIMITED     145
+
+  55.--STERILISING APPARATUS FOR STERILISING MILK ON
+         THE LARGE SCALE                                      146
+
+  56.--ANOTHER METHOD OF STERILISING (DAIRY SUPPLY
+         CO., LTD.). AN AMERICAN APPARATUS FOR PREPARING
+         SOURED MILK                                          148
+
+  57.--AN AMERICAN APPARATUS FOR PREPARING SOURED MILK        149
+
+
+
+
+THE BACILLUS OF LONG LIFE
+
+
+
+
+CHAPTER I
+
+INTRODUCTORY--HISTORICAL
+
+
+The milk industry is one of the oldest known to mankind, and it is
+difficult to imagine a time when milk in one way or another did not form
+a part of the diet of the human race. There is a good deal of evidence
+to show that in Paleolithic and Neolithic times, cattle were part of the
+possessions of the nomadic races; and, according to the Vedas, the
+manufacture of butter was known in India 1500 years B.C.
+
+In the eastern part of Europe, milk has always been looked upon as one
+of the principal kinds of food, but not necessarily the milk of cows,
+as, from ancient times to the present day, the milk from camels,
+buffaloes, sheep, and goats has been used indiscriminately throughout
+the East.
+
+According to Layard,[1] "the Bedouins do not make cheese. The milk of
+their sheep and goats is shaken into butter or turned into curds; it is
+rarely or never drunk fresh, new milk being thought very unwholesome, as
+soon by experience I found it to be, in the desert. I have frequently
+had occasion to describe the process of making butter by shaking the
+milk in skins. This is also an employment confined to women, and one of
+a very laborious nature. The curds are formed by boiling the milk, and
+then putting some curds made on the previous day into it and allowing it
+to stand. When the sheep no longer give milk, some curds are dried, to
+be used as a leaven on a future occasion. This preparation, called
+_leben_, is thick and acid, but very agreeable and grateful to the taste
+in a hot climate. The sour milk, or _sheneena_, a universal beverage
+amongst the Arabs, is either buttermilk pure and diluted, or curds mixed
+with water.
+
+  [Illustration: THE PASS OF BUKOVA.--During the revolution
+  of 1904, a number of Turkish soldiers, just before
+  traversing this pass, were given coffee containing "cafe"
+  by a Bulgarian coffee-seller, or keeper of a small khan.
+  Whilst in the pass the poison began to take effect, and
+  they realized that they had been poisoned. Fortunately for
+  them, a peasant with three horses loaded with Yoghourt
+  (soured milk) had taken advantage of their escort. The
+  soldiers ate freely of the Yoghourt, which counteracted
+  the effects of the poison.]
+
+"The camel's milk is drunk fresh. It is pleasant to the taste, rich, and
+exceedingly nourishing. It is given in large quantities to the horses.
+The Shammar and Aneyza Bedouins have no cows or oxen, those animals
+being looked upon as the peculiar property of tribes who have forgotten
+their independence, and degraded themselves by the cultivation of land.
+The sheep are milked at dawn, or even before daybreak, and again in the
+evening on their return from the pastures. The milk is immediately
+turned into leben, or boiled to be shaken into butter. Amongst the
+Bedouins and Jebours it is considered derogatory to the character of a
+man to milk a cow or sheep, but not to milk the camel. The Sheikhs
+occasionally obtain dates from the cities. They are eaten dry with bread
+and leben, or fried in butter, a very favourite dish of the Bedouin...."
+
+The practice is now the same as it was in scriptural times, when milk
+was looked upon as the principal article of diet, and throughout the
+Scriptures there are copious references to milk in different forms, some
+of which are of peculiar interest at the present day.
+
+It may be noticed, for example, that milk is absent from the sacred
+offerings amongst the Hebrews, and this was ascribed by the late
+Professor Robertson Smith to the fact that all ferments were excluded
+from presentation at the altar,[2] it being recognised that, owing to
+the hot climate, milk of all kinds became rapidly sour, and in this way
+came to be looked upon as only fit for consumption when in that
+condition. It has been suggested that the prohibition referred to is on
+the same level as the prohibition of the use of blood, "as milk has
+sometimes been regarded as a kind of equivalent for blood, and
+containing the sacred life."[3] To this day the wandering tribes of
+Arabia consider the milk of their camels and flocks more refreshing when
+it has been slightly fermented or soured by being poured into a
+milk-skin on the inside of which are still sticking sour clots from the
+previous milking, and there shaken for a brief period; but this slightly
+soured milk (the _Oxygala_ of Pliny) is known widely in the East simply
+as leben (milk). The name is also applied to what we term buttermilk.[4]
+
+  [Illustration: KABYLES SOURING MILK
+
+  In the north of Africa the use of soured milk is common,
+  and the illustration shows Kabyles shaking a skin full of
+  milk so as to sour it. The skin has previously been used
+  for the same operation, and, as a consequence, clots of
+  milk are left from the previous day's use, and thus
+  fermentation is set up.]
+
+The use of milk-skins for the carrying of milk is not confined to one
+country, as, while it is common all over the north of Africa, it is also
+known in the Pyrenees and in some parts of the Balkan Peninsula, the
+object being identical in each case; and when it is intended to make
+butter from the milk, the skin is simply rocked between the knees until
+the butter separates, a process of butter-making which was also used
+after the introduction of earthenware churns.[5] Dried soured milk is
+also used by the Arabs, and it is reconstituted when required by rubbing
+it up with a little water, and it is known as _Meeresy_.[6] The ordinary
+soured milk is the common article of diet, and is looked upon as being
+necessary at every meal, and travellers frequently refer to the use of
+this product, as a few references will show.
+
+Charles G. Addison states: "A supper was brought in on a round tray. In
+the centre was a huge pilaff of rice, and around it several small dishes
+of stewed meats, grilled bones, sour clotted milk called _yaoort_,[7]
+bits of meat roasted, etc....
+
+"We retired into a tent to breakfast, where we found an immense bowl of
+delicious fresh camels' milk, with thin hot cakes of unleavened bread,
+baked upon the ashes, ready prepared for us. The principal food of the
+Bedouins consists of flour and some camels' milk made into a paste,
+boiled, and eaten swimming in melted grease and butter; boiled wheat
+and beans dried in the sun and prepared with butter are a favourite
+dish. They are all remarkably fond of butter and grease; the butter is
+made in a goat-skin, suspended to the tent pole, and constantly shaken
+about by the women."[8]
+
+Burckhardt[9] says: "The provisions of my companion consisted only of
+flour; besides flour, I carried some butter and dried leben (sour milk),
+which would dissolve in water. It forms not only a refreshing beverage,
+but is much to be recommended as a preservative of health when
+travelling in summer. These are our only provisions." With regard to the
+inhabitants of the Houran, Burckhardt relates that the most common
+dishes of these people are _bourgoul_ and _keshk_. "In summer they
+supply the place of the latter by milk, leben, and fresh butter. Of the
+bourgoul I have spoken on other occasions; there are two kinds of
+keshk--_keshk-hammer_ and _keshk-leben_. The first is prepared by
+putting leaven into the bourgoul and pouring water over it. It is then
+left until almost putrid, and afterwards spread out in the sun and
+dried, after which it is pounded, and, when called for, served up mixed
+with oil or butter. The keshk-leben is prepared by putting leben into
+the bourgoul instead of leaven; in other respects the process is the
+same. Keshk and bread are the common breakfasts. Towards sunset a plate
+of bourgoul, or some Arab dish, forms the dinner."
+
+Again, Taylor[10] says: "I received a small jug of thick buttermilk, not
+remarkably clean, but very refreshing."
+
+These references particularly refer to the East, from which it would
+appear that soured milk was universally known in ancient times as it is
+at the present day, and this remark applies not only to Egypt,
+Palestine, and Arabia, but throughout Turkey and the Balkan States,
+where the consumption of soured milk is equally common. It seems curious
+that the use of this commodity should have been confined for centuries
+to the East, as we shall see later on that its dietetic value is so
+great that it is really a wonderful thing that no one has taken the
+trouble to introduce its use to the Western nations until quite
+recently.
+
+  [Illustration: THE HANDLING OF MILK IN THE PYRENEES
+
+  The handling of milk in the Pyrenees is, more especially
+  in the villages, conducted in goat or sheep skins, in a
+  similar way to the methods which prevail in Eastern
+  Europe, and the picture shows a skin of milk on a small
+  farm in the Pyrenees. The churning is very often performed
+  by simply rocking the skin between the knees, acidity
+  being induced by remnants of the previous day's milk;
+  souring of milk is induced by the same method.]
+
+A curious example of how the virtues of such an article may be
+independently discovered by another nation is to be found in Lapland,
+where reindeer's milk is the article used. "The reindeer's milk," says
+Acerbi,[11] "constitutes a principal part of the Laplander's food, and
+he has two methods of preparing it, according to the season. In summer
+he boils the milk with sorrel till it arrives to a consistence; in this
+manner he preserves it for use during that short season. In winter the
+following is his method of preparation: The milk, which he collects in
+autumn till the beginning of November, from the reindeer, is put into
+casks, or whatever vessels he has, in which it soon turns sour, and, as
+the cold weather comes on, freezes, and in this state it is kept. The
+milk collected after this time is mixed with cranberries and put into
+the paunch of the reindeer, well cleaned from filth; thus the milk soon
+congeals, and it is cut out in slices, together with the paunch, to
+effect which a hatchet is used, for no smaller instrument would perform
+the office of dividing that lump of ice. It is then separated into small
+pieces and eaten throughout the winter every day at noon, which is the
+Laplander's dinner-hour. It must be presumed, as it is served up without
+being brought to the fire, that this is ice-cream in the greatest
+perfection: here are flesh and fruit blended with the richest
+butyraceous milk that can be drawn from any animal; but, notwithstanding
+the extraordinary fatness, which may be supposed to resist in a great
+degree the effect of cold, this preparation, as our good missionary
+remarks with a degree of feeling, as if his teeth still chattered whilst
+he delivered the account, chills and freezes the mouth in a violent
+manner whenever it is taken. The milk which is drawn late in the winter
+freezes immediately after being drawn. This is put into small vessels
+made of birchwood, and is considered by the Laplander as such an
+extraordinary delicacy, that he reserves it as the most acceptable
+present he can offer even a missionary. It is placed before the fire and
+eaten with a spoon as it is thawed. When put by, it is carefully covered
+up, because if the cold air gets to it afterwards, it turns of a yellow
+colour and becomes rancid."
+
+Amongst the peasants at the present day, soured milk is known as
+_yoghourt_, a word which is spelt differently according to the locality
+in which it is used. The method of preparation is practically the same
+everywhere, and a short description of the process as now carried out
+in one place would, with slight modifications, apply to the general
+method adopted all over the East.
+
+"The culture," says a correspondent at Varna, "which is used for the
+preparation of yogourt, is known as 'Maya' or as 'Bulgarian Maya.' The
+milk which is to be converted into yogourt must first be freed from all
+bacteria by boiling and allowed to cool to the temperature of 45 deg. C.;
+it is then inoculated with maya and maintained at an even temperature of
+45 deg. C. during several hours. There are two kinds of maya, or ferment,
+one known as sour, and the other as sweet maya.
+
+"In Europe small stoves, made expressly for the purpose, are used to
+maintain the milk at the proper temperature. In this country, however,
+after the milk has been boiled, it is merely poured into a bowl and
+allowed to cool to approximately 45 deg. C., then a tablespoonful of this
+tepid milk is well mixed (in a small bowl apart) with a similar quantity
+of maya, and the mixture, when it has become quite homogeneous, is added
+to the bowl of tepid milk and stirred slightly. (One tablespoonful of
+maya is sufficient to ferment one litre of milk.) A cover is then placed
+on the bowl and the whole is enveloped in flannel and left in a warm
+place for three hours in summer, and somewhat longer in winter.
+
+"The process of preparation is complete when the mixture assumes the
+appearance of a soft mass somewhat resembling cream cheese, but less
+solid. The flannel is then removed, the bowl uncovered and placed in a
+cool spot until needed for consumption. Of the yogourt thus prepared, a
+tablespoonful is kept to serve as maya for the following day.
+
+"The best yogourt is prepared from sheep's milk, the second quality from
+buffaloes' milk, and the third quality from cows' milk. Yogourt forms an
+almost daily article of diet with the natives in this country."[12]
+
+With regard to the time stated for the fermenting process, it must be
+noted that since the subject has been investigated so thoroughly, the
+time required for fermentation has been found to be nearer ten than
+three hours, but this will be dealt with in a subsequent chapter.
+
+Historically it may be gleaned from the fragmentary references which we
+have given, that soured milk has, from time immemorial, formed the
+principal article of diet of a great many peoples, and the notable
+feature in connection with it is, that in some countries where it is in
+daily use, the age limit for human beings seems to be very much
+extended, and it would appear that there is a direct connection between
+the use of soured milk and longevity. In Bulgaria, for example, it is
+stated that the majority of the natives live to an age considerably in
+excess of what is recognised as the term of life amongst Western
+nations, and inquiry has shown that in the eastern part of Southern
+Europe, amongst a population of about three millions, there were more
+than three thousand centenarians found performing duties which would not
+be assigned to a man of sixty-five years of age elsewhere. It is quite
+common to find amongst the peasants who live to such a large extent upon
+soured milk, individuals of 110 and 120 years of age.[13]
+
+In the ancient dairy practice, as we have seen, soured milk was the
+principal product, and the extraordinary ages which are recorded of the
+patriarchs, if translated into the modern denomination, would not appear
+to be so imaginary after all, when it is considered that we have
+thousands of examples at the present day of men and women enjoying quite
+as long a term of existence. It has been noticed also, that while these
+very old people are able to perform a certain amount of manual labour,
+there is not the same tendency to the mental decay which is so prominent
+and sad a feature amongst Western nations, at a period of about seventy
+or eighty years of age. It would seem, indeed, as if the habit of living
+long was well known in ancient times, and that, like many other of the
+valuable arts and sciences, it fell under a cloud during the Middle
+Ages, or, perhaps, the significance of the use of soured milk fell into
+neglect, and, even after the revival of letters in the sixteenth
+century, still remained obscure.
+
+The discovery of micro-organisms in perishable products, which is
+attributable to Anthony Van Leeuwenhoek, a Dutchman, whose vocation was
+the polishing of lenses, and who lived between 1632 and 1723, altered
+our point of view, not only of disease, but of all the functions carried
+on by the lower organisms. Since Van Leeuwenhoek's time, the germ theory
+has grown to vast proportions and has more especially been applied with
+splendid results to the study of milk. As we shall see later, the
+researches of modern investigators have led them to the conclusion that
+micro-organisms play such an important part in the milk supply, that it
+is impossible to carry it on safely without a knowledge of the
+bacteriology of the subject. This view began to prevail about 1890, some
+twenty years after Pasteur had shown what fermentation really meant.
+Since that time, the progress in dairying has been continuous, and,
+during recent years, attention has been directed to soured milk to such
+an extent that it has become necessary for all who are interested in the
+handling of milk and milk products to have a knowledge of the subject,
+as it seems clearly demonstrated that, under proper direction, there is
+every possibility of its forming an important element in the
+prolongation of life.
+
+
+
+
+CHAPTER II
+
+FERMENTED MILKS
+
+
+There is considerable variety in the number of soured or fermented
+milks, and they are known by various names, such as Koumiss or Koomiss,
+which is prepared from mares' milk; Keffir, which was originally
+discovered in the mountains of the Caucasus, and which is prepared with
+Keffir grains; Leben, an Egyptian product prepared from the milk of the
+buffalo, cow, or goat; Matzoon, a soured milk which is prepared in
+Armenia from ordinary cows' milk; Dadhi, an Indian preparation from
+cows' milk. All of these owe their special characteristics to the fact
+of their having undergone lactic and alcoholic fermentation.
+
+"Milk left to itself," says Blyth,[14] "at all temperatures above 90 deg.
+F. begins to evolve carbon dioxide, and this is simply a sign and result
+of fermentation. If this fermentation is arrested or prevented, the fluid
+remains perfectly sweet and good for an indefinite time. Besides the
+production of carbon dioxide during decomposition, a certain portion of
+milk sugar is converted into lactic acid, some of the casein and albumen
+are broken up into simpler constituents, and a small proportion of
+alcohol produced, which by oxidation appears as acetic acid, while the
+fat is in part separated into free fatty acids, which ultimately unite
+with the ammonia produced by the breaking up of the albuminoids. The
+main fermentation of milk is a special kind which of late years has been
+much studied, and is known as _lactic fermentation_. Accompanying lactic
+fermentation there is nearly always a weak butyric and a weak alcoholic
+fermentation."
+
+One of the organisms causing _Butyric Acid Fermentation_ is a bacillus 3
+to 10 mu in length, and about 1 mu in breadth. It has power of movement, and
+when cultivated in gelatine, liquefies the gelatine, forming a scum on
+the surface. When the bacillus is sown into sterile milk, the following,
+according to Hueppe, are the changes:
+
+"If the milk thus infected is incubated, on the second day a clear,
+slightly yellow fluid is seen under the layer of cream; this fluid
+increases from day to day, so that gradually a column of fluid is
+formed which is quite clear above, but below is turbid; the casein, at
+first thrown down in a firm coagulum, in the course of eight days begins
+to be attacked, and by the end of two or three weeks most of it is
+dissolved. The filtered fluid gives the biuret reaction; it contains
+leucin, tyrosin, and ammonia; hence it is clear that the ferment acts to
+some extent as a digestive of albumen. In advanced butyric acid
+fermentation, the fluid is most offensive, and may have an alkaline
+reaction."
+
+Lactic acid was first isolated by Scheele in 1780 from soured milk, but
+its exact constitution was not determined until later by Liebig,
+Mitscherlich, Gay-Lussac, and Pelouze: "It is widely distributed in
+nature, occurring in the sap of the vine and in most fermented liquids,
+especially in soured milk; it is not, however, present in fresh
+milk."[15]
+
+In all the Eastern preparations referred to, the lactic fermentation is
+produced, followed by alcoholic fermentation, which is due to the slow
+decomposition of the milk sugar, the vinous fermentation being most
+readily set up in milks which contain a larger relative proportion of
+milk sugar and water, such as the milk derived from the mare, the sheep,
+and the camel. As these fermented milks have different characteristics,
+it is necessary to the thorough understanding of the process of
+manufacture at the present day, to examine them in some detail.
+
+_Koumiss._--The greatest of all the fermented milks is koumiss, and it
+has been celebrated from the most ancient times until the present day,
+as being the principal food of the wandering tribes of Khirgiz,
+Bashkirs, Kalmucks, and Tartars, who inhabit the steppes of European
+Russia and the plains of South, Western, and Central Asia. According to
+Carrick, who has written an interesting volume on the subject,[16] the
+nomads who inhabit these vast territories are shut up under the most
+miserable circumstances during the winter time and at the advent of
+spring they roam over the steppes from morning to night, usually in the
+saddle. The milk yielded at such time by the mares is carefully
+collected, and these nomads consume enormous quantities of it in the
+fermented state, this habit having been in existence amongst them from
+time immemorial. It is said that the Scythians, long before the
+Christian era, used fermented mares' milk; and there are ornaments in
+existence in Russia, of Scythian origin, which exhibit in detail the
+preparation of koumiss from mares' milk. In historical times, the first
+mention of koumiss was in the twelfth century, when it is referred to in
+the Ipatof Chronicles. During the thirteenth century William de
+Rubruquis, a French missionary, wrote about his travels in Tartary, and
+he described how he had first become acquainted with koumiss, and how he
+found it savoury to the palate. Subsequent to this, however, there is
+very little mention of koumiss in Russian history, or, for that matter,
+in any other, and the first really scientific contribution on the
+subject was by Dr. John Grieve, who was a surgeon in the Russian army,
+and who in the year 1784 sent a description of koumiss to the Royal
+Society of Edinburgh,[17] of which he was a member, and the title of it
+was, "An Account of the Method of Making Wine called by the Tartars
+Koumiss, with Observations on its Use as a Medicine." Dr. Grieve
+strongly advocated the use of koumiss as beneficial in cases of wasting
+diseases, and subsequently it was adopted by the medical profession,
+with the result that sanatoria for the treatment of pulmonary
+consumption were established at Samara and other places in Russia, and
+met with very great success; and at the present day such sanatoria are
+carried on, but the bacteriology of the subject now being thoroughly
+understood, the methods of preparation have been somewhat modified.
+
+An interesting account of koumiss is given by Clarke,[18] who says:
+
+"Everybody has heard of koumiss, and the brandy which the Kalmucks are
+said to distil from the milk of mares. The manner of preparing these
+liquids has been differently related, and perhaps is not always the
+same. They assured us that the brandy was merely distilled from
+buttermilk. The milk which they collect overnight is churned in the
+morning into butter; and the buttermilk is distilled over a fire made
+with the dung of their cattle, particularly the dromedary, which makes a
+steady and clear fire like peat. But other accounts have been given both
+of the koumiss and the brandy. It has been usual to confound them, and
+to consider the koumiss as their appellation for the brandy so obtained.
+By other information I could gain, not only here, but in many other
+camps which we afterwards visited, they are different modifications of
+the same thing although different liquors; the koumiss being a kind of
+sour milk, like that so much used by the Laplanders called _pina_, and
+which has undergone, in a certain degree, the vinous fermentation; and
+the brandy an ardent spirit obtained from koumiss by distillation. In
+making koumiss they sometimes employ the milk of cows, but never if
+mares' milk can be had, as the koumiss from the latter yields three
+times as much brandy as that made from cows' milk.
+
+"The manner of preparing the koumiss is, by combining one sixth part of
+warm water with any given quantity of warm mares' milk. To these they
+add, as a leaven, a little old koumiss, and agitate the mass till
+fermentation ensues. To produce the vinous fermentation, artificial heat
+and more agitation is sometimes necessary. This affords what is called
+koumiss. The subsequent process of distillation afterwards obtains an
+ardent spirit from the koumiss. They call it _vina_. In their own
+language it bears the very remarkable appellation of _rack_ and _racky_,
+doubtless nearly allied to the names of our East India spirit _rack_
+and _arrack_. We brought away a quart bottle of it, and considered it
+very weak bad brandy, not unlike the common spirit distilled by the
+Swedes and other northern nations. Some of their women were busy making
+it in an adjoining tent. The simplicity of the operation and their
+machinery was very characteristic of the antiquity of this chemical
+process. Their still was constructed of mud, or very coarse clay; and
+for the neck of the retort they employed a cane. The receiver of the
+still was entirely covered by a coating of wet clay. The brandy had
+already passed over. The woman who had the management of the distillery,
+wishing to give us a taste of the spirit, thrust a stick, with a small
+tuft of camel's hair at its end, through the external covering of clay,
+and thus collecting a small quantity of the brandy, she drew out the
+stick, dropped a portion on the retort, and, waving the instrument above
+her head, scattered the remaining liquor in the air. I asked the meaning
+of this ceremony, and was answered that it is a religious custom to give
+always the first drop of the brandy which they draw from the receiver to
+their God. The stick having been plunged into the receiver again, she
+squeezed it into the palm of her dirty and greasy hand, and after
+tasting the liquor, presented it to our lips."
+
+Another interesting account of the preparation of koumiss is given by
+John M. Wilson in the _Rural Encyclopaedia_,[19] and it shows that the
+methods in use about the middle of last century did not differ
+materially from those which existed centuries before.
+
+Wilson says: "Khoumese is vinously fermented mares' milk. Any quantity
+of fresh mares' milk is put into wooden vessels; a sixth part of water
+just off the boil is mixed with it; an eighth part of old khoumese or of
+the sourest possible cows' milk is added; the mixture is kept from
+fifteen to twenty-four hours, covered up with several folds of coarse
+linen cloth and with a very thick board, and without being stirred or in
+any degree disturbed, in a moderately warm place till it becomes
+thoroughly sour, and sends up a thick mass to its surface; it is then
+beaten and pounded and stirred till the curd is not only broken, but so
+thoroughly mixed with the serum as to form a thick liquid; it next
+remains covered and at rest during twenty-four hours more, and it is
+finally put into a common butter churn and beaten and blended into a
+state of perfect homogeneity. It is now fit for use; yet it acquires an
+increase of given properties if it be allowed to stand for a few days,
+and either then or now it would, if distilled, yield nearly one third of
+its own bulk of a weak spirit which will bear to be rectified. Whenever
+it is used it must be previously so agitated that its component parts
+may be well mixed together, and it may be kept either in pans for
+immediate use or in casks for more remote use; and if placed in a cool
+cellar it will remain good during three or four months."
+
+Mares' milk owes its peculiar fitness for making koumiss to its
+containing a large proportion of sugar of milk, and readily undergoing
+the vinous fermentation, and it possesses a general medicinal reputation
+among the Tartars similar to that which asses' milk has partially
+acquired in Britain. "That mares' milk will undergo vinous fermentation
+and yield a certain quantity of spirit," says a writer in the _Magazine
+of Domestic Economy_, "is not generally known, and it was reserved for a
+nation of demi-savages to render this circumstance available as an agent
+of health, as well as an agreeable and nourishing beverage. Every
+educated person, however, has heard that the Tartars drink mares' milk,
+though few know that this milk is taken on account of its specific
+virtues alone, and not as a substitute for cows' milk, of which they
+have abundance, and with which they adulterate mares' milk when scarce."
+But the koumiss is reputed to be much more medicinal than the mares'
+milk itself; and on account of its being free from all tendency to
+curdle in the stomach, and of its possessing most of the nutritive power
+of the milk in combination with native fermented spirit, it has been
+strongly recommended by some persons as a remedy for most or all cases
+of general debility, of nervous languor, and even pulmonary disease.
+
+"Khoumese is called sometimes _koumiss_ and sometimes milk wine."
+
+From these references it will be seen that koumiss is an alcoholic drink
+made by the fermentation of mares' milk, but it is also frequently
+prepared from the milk of the camel and cows' milk. It is stated that a
+similar preparation to Russian koumiss is made in Switzerland from cows'
+milk simply by the addition of a little sugar and yeast to skim milk;
+"it contains more sugar and less lactic acid than Russian koumiss, and
+on account of the much greater proportion of casein contained in cows'
+milk, differs considerably from that prepared from mares' milk."
+Suter-Naef gives the composition of a Swiss koumiss[20] manufactured at
+Davos as follows:
+
+                      In Grams.             Per Litre
+                      Per cent.            (by weight).
+  Water                90.346               1019.64 grams.
+  Alcohol               3.210                 36.23   "
+  Lactic acid           0.190                  2.14   "
+  Sugar                 2.105                 23.75   "
+  Albuminates           1.860                 20.99   "
+  Butter                1.780                 20.09   "
+  Inorganic salts       0.509                  5.74   "
+  Free carbonic acid    0.177                  2.00   "
+
+The ferments used in the preparation of koumiss are stated by Carrick to
+be of two different kinds, artificial and natural.
+
+"Of the natural ferments two have been resorted to. One is mentioned by
+Grieve, which he borrowed from the Bashkirs of Orenbourg, and which
+simply consists in the addition of one sixth part of water and one
+eighth of the sourest cows' milk to fresh mares' milk; the other has
+been employed, and was, if I mistake not, first recommended by
+Bogoyavlensky. It is a very simple if rather a tedious method. New
+mares' milk, diluted with one third its bulk of water, is placed in the
+_saba_,[21] and while allowed to sour spontaneously, is continually
+beaten up. This milk gradually undergoes the vinous fermentation, and in
+twenty-four hours is converted into weak koumiss. The disadvantage of
+this mode of commencing fermentation is obvious--viz., the great waste
+of time in agitation. Hence it is only employed when no artificial
+ferment is obtainable.
+
+"In starting the process of fermentation in mares' or any other kind of
+milk, therefore, an artificial ferment is more frequently employed than
+a natural one. The former is used only for converting the first portion
+of milk into koumiss; the latter is always resorted to afterwards.
+
+"Of artificial ferments the variety is great, for besides all putrefying
+animal matters which contain nitrogen--such as blood, white of egg,
+glue, and flesh--certain mineral substances which act by souring the
+milk are also capable of exciting fermentation.
+
+"Now, many of the nomads, whose mares either give no milk or are not
+milked in winter, commence the preparation of their koumiss in spring by
+borrowing a ferment from the animal, mineral, or vegetable kingdom. Thus
+a mixture of honey and flour is the favourite ferment with some races of
+nomads; a piece of fresh horse-skin or tendon is preferred by others,
+while a few resort to old copper coins, covered with verdigris, for
+starting fermentation. In the choice of a ferment they are guided solely
+by habit and tradition. As it would be useless, almost impossible, to
+give a list of all the foreign substances that have been employed with
+the view of converting mares' milk into koumiss, it will be best to
+consider the simplest artificial ferments, and those most generally in
+use.
+
+"The simplest way is that recommended by Bogoyavlensky, and adopted and
+modified by Tchembulatof.[22] It is prepared thus: 'Take a quarter of a
+pound of millet-flour, add water to it, and boil it down to the
+consistence of thick oatmeal porridge. Then heat separately, in another
+vessel, eleven pints of milk to boiling-point, and allow it to cool
+down. When its temperature has fallen to 95 deg. F., pour it into a wooden
+bowl or tub, and add the boiled flour to it. The upper and open part of
+the vessel is then covered with a piece of coarse linen, and left at
+rest--at a temperature of about 99 deg. F.--from twenty-four to forty-eight
+hours. The appearance of small bubbles, which keep bursting on the
+surface of this liquid, combined with a vinous or acid odour, prove that
+the ferment is ready. To this fermenting fluid twenty-two quarts of new
+milk are gradually (_i.e._, every ten minutes) added, and the whole mass
+is continuously beaten up for twelve hours. The temperature during
+stirring should never be higher than 94 deg. F. The whole fluid soon begins
+to ferment, and after twelve hours a not unpleasant koumiss is ready.
+This should be filtered through a horse-hair or muslin sieve, after
+which it is fit for drinking. This liquid is called weak koumiss; but a
+limited portion of the lactine has undergone the lactuous and vinous
+fermentations, and thus the percentage of alcohol is small. Koumiss at
+an ordinary temperature remains weak for twelve hours after it has been
+beaten up, and then gradually passes into medium.'"
+
+Curiously enough, the richness of cows' milk in fat militates against
+its being a good raw material for the making of koumiss, owing to the
+production of small quantities of butyric acid, which follows upon the
+fermentation, so that it is desirable, if koumiss is to be prepared from
+cows' milk, that the fat should be first of all eliminated, so that the
+separated milk will then approximate to the composition of mares' milk.
+
+"The chemical changes," says Hutchison,[23] "which take place in the
+milk under the double fermentation are not difficult to follow; the
+lactic ferment simply changes part of the sugar into lactic acid, the
+vinous ferment eats up a very small part of the proteid of the milk,
+and, at the same time, produces from the sugar a little alcohol and a
+good deal of carbon dioxide; the milk thus becomes sour, it effervesces
+and is weakly alcoholic, but the lactic acid causes the casein to be
+precipitated just as it does in the ordinary souring of milk, and the
+casein falls down in flocculi."
+
+As will have been noticed, it is an essential part of the process of
+koumiss-making to keep the milk in a state of agitation during the
+period of fermentation, a process which is intended to permit of oxygen
+being taken up by the fermenting fluid, while, at the same time, the
+casein is broken up into a state of fine division. The casein also, or
+at least a portion of it, becomes very soluble, and after twelve hours
+of fermentation the taste of the product is only slightly sour, and the
+milk taste still remains. This taste, however, disappears in
+twenty-four hours, owing to the rapid development of the lactic acid
+organisms. After this lapse of time the sugar is entirely destroyed, and
+the strong koumiss which results is a thin sour fluid which effervesces
+briskly, and in this condition will keep for an indefinite period. "The
+net change which has taken place in the original milk may be summed up
+by saying that the sugar of the milk has been replaced by lactic acid,
+alcohol, and carbon dioxide, the casein has been partly precipitated in
+a state of very fine division, and partly pre-digested and dissolved,
+while the fat and salts have been left much as they were."[24]
+
+Violent stirring or agitation of the cultures does not seem to work so
+much by supplying oxygen to the fermenting liquid, as by ensuring a
+thorough distribution of the micro-organisms throughout the liquid, and
+thus dividing the casein.
+
+The greater number of the organisms are facultative anaerobes and oxygen
+is not necessary. Again, koumiss put up in bottles on the first day is
+regularly shaken although air is excluded.
+
+_Keffir._--Keffir is a kind of fermented milk which has been in use in
+the Caucasus for quite a long time, as koumiss has been in the steppes.
+It differs from koumiss, however, in this respect, that it is prepared
+from either sheep's, goats', or cows' milk. The process is started by
+the addition of keffir grains to the milk, which is contained in
+leathern bottles. These keffir grains are small solid kernels which are
+kept in families and handed on from one generation to another.[25] The
+grains are the origin of the ferment, as they disseminate in the milk
+micro-organisms of a lactic yeast (_Saccharomyces kefir_ Beyerinck and
+Freudenreich) and also the bacillus _Bacterium caucasicum_, which
+develop rapidly and split up the milk sugar into carbon dioxide,
+alcohol, and lactic acid. Small quantities of glycerine, acetic,
+succinic, and butyric acids are also formed, the casein and albumen
+being partly peptonised.[26] Keffir becomes slightly effervescent in
+twenty-four hours, and in that time develops a small quantity of
+alcohol, but after three days the amount of alcohol and lactic acid
+is much increased.[27] It has been determined that the fermentation of
+the milk is due to _Saccharomyces kefir_, and that the _Lactobacillus
+Caucasicus_ does not take any part in the fermentation, a fact which
+seems to be supported by the capacity of ordinary keffir for starting
+the fermentation in fresh milk in the same manner as the keffir grains.
+The use of this beverage seems to be universal throughout the Caucasus,
+and travellers in these regions have frequently referred to it. Thus
+Freshfield[28] states in one part of his book of travels as follows:
+
+"The pig-faced peasant against whom we had at first sight conceived such
+an unjust prejudice turned out a capital fellow. He brought us not only
+fresh milk, but a peculiar species of liquor, something between
+public-house beer and sour cider, for which we expressed the greatest
+admiration, taking care at the same time privately to empty out the
+vessel containing it, on the first opportunity." And again:
+
+"The hospitable shepherds regaled us, not only with the inevitable and
+universal airam or sour milk--if a man cannot reconcile himself to sour
+milk, he is not fit for the Caucasus--but with a local delicacy that
+has lately been brought to the knowledge of Europe--kefir. This may best
+be described as 'effervescing milk.' It is obtained by putting into the
+liquid some yellow grains, parts of a mushroom which contains a bacillus
+known to science as _Dispora caucasia_. The action of the grains is to
+decompose the sugar in the milk, and to produce carbonic acid and
+alcohol. The grains multiply indefinitely in the milk; when dried they
+can be preserved and kept for future use; its results on the digestion
+are frequently unsatisfactory, as one of my companions learnt to his
+cost."
+
+"It has been supposed," says Metchnikoff, "that the chief merit of
+kephir was that it was more easy to digest than milk, as some of its
+casein is dissolved in the process of fermentation. Kephir, in fact, was
+supposed to be partly digested milk. This view has not been confirmed.
+Professor Hayem thinks that the good effects of kephir are due to the
+presence of alcoholic acid, which replaces the acid of the stomach and
+has an antiseptic effect. The experiments of M. Rovigh, which I speak of
+in _The Nature of Man_, have confirmed the latter fact, which now may be
+taken as certain. The action of kephir in preventing intestinal
+putrefaction depends on the lactic acid bacillus which it contains.
+Kephir, although in some cases certainly beneficial, cannot be
+recommended for the prolonged use necessary, if intestinal putrefaction
+is to be overcome.... Professor Hayem prohibits its use in the case of
+persons in whom food is retained for long in the stomach. When it is
+retained in the stomach, kephir goes on fermenting, and there are
+developed in the contents butyric and acetic acids, which aggravate the
+digestive disturbances. Kephir is produced by combined lactic and
+alcoholic fermentations ... and it is the lactic and not the alcoholic
+fermentation on which the valuable properties of kephir depend; it is
+correct to replace it by sour milk, that contains either no alcohol or
+merely the smallest traces of it. The fact that so many races make sour
+milk and use it copiously is an excellent testimony of its usefulness."
+
+There are two methods given by Fluegge[29] for the preparation of keffir:
+
+"In the first, the dry brown kefir grains of commerce are allowed to lie
+in water for five or six hours until they swell; they are then carefully
+washed and placed in fresh milk, which should be changed once or twice
+a day until the grains become pure white in colour and when placed in
+fresh milk, quickly mount to the surface--twenty to thirty minutes. One
+litre of milk is then poured into a flask, and a full tablespoonful of
+the prepared _koerner_ added to it. This is allowed to stand open for
+five to eight hours; the flask is then closed and kept at 18 deg. C. It
+should be shaken every two hours. At the end of twenty-four hours the
+milk is poured through a fine sieve into another flask, which must not
+be more than four fifths full. This is corked and allowed to stand,
+being shaken from time to time. At the end of twenty-four hours a drink
+is obtained which contains but little carbon-dioxide or alcohol. Usually
+it is not drunk until the second day, when, upon standing, two layers
+are formed, the lower milky, translucent; and the upper containing fine
+flakes of casein. When shaken it has a cream-like consistence. On the
+third day it again becomes thin and very acid. The second method is used
+when one has a good kefir and two or three days to start with. Three or
+four parts of fresh cows' milk are added to one part of this and poured
+into flasks which are allowed to stand for forty-eight hours with
+occasional shaking. When the drink is ready for use, a portion (one
+fifth to one third) is left in the flask as ferment for a fresh quantity
+of milk. The temperature should be maintained at about 18 deg. C., but at
+the commencement a higher temperature is desirable. The grains should be
+carefully cleaned from time to time and broken up to the size of peas.
+The clean grains may be dried upon blotting-paper, in the sun, or in the
+vicinity of a stove; when dried in the air they retain their power to
+germinate for a long time."
+
+_Leben._--In our earlier references to fermented milks in scriptural
+times, we observed that alcoholic fermented milks were not permitted to
+be presented at the altar. Such offerings, however, were quite allowable
+amongst the ancient Egyptians, the Arabs and Carthaginians,[30] and from
+remote antiquity these nations placed great value on this product.
+Leben, which is peculiarly associated with Egypt, is a soured milk
+prepared from the milk of buffaloes, cows, or goats. It is usually
+prepared by the boiling of the fresh milk over a slow fire, after which
+some fermented milk from a previous preparation is added to the warm
+article, and the fermentation takes place rapidly and is considered to
+be complete in about six hours.[31] The Egyptian leben is valued so
+highly that it is offered in hospitality to the passing stranger, and it
+is regarded as so much of a duty to present this milk, that in some
+parts of Arabia it would be looked upon as scandalous if any payment
+were received in return.[32]
+
+_Matzoon._--Matzoon is prepared in Armenia in somewhat the same manner
+as keffir is prepared in the Caucasus, and indeed it differs very
+slightly from keffir in composition. Its use is universal in Armenia.
+
+_Dadhi._--In India large quantities of fermented milk are used, under
+the name of Dadhi, and its characteristics are not unlike the similar
+products in Europe. The specific bacillus has been investigated by
+Chatterjee,[33] who concludes that it is somewhat akin to the _Bacillus
+bulgaricus_ and the bacillus of leben (_B. lebenis_). Dr. Chatterjee
+gives a resume of his investigations which sums up the whole matter
+thus:
+
+"1. The fermented milk of India called Dadhi resembles in all essential
+points the Bulgarian fermented milk as well as the leben and other forms
+of fermented milk in use in the East.
+
+"2. The causative element of the curdling process of Dadhi is a
+streptothrix having characters similar to the _Bacillus bulgaricus_ and
+_Streptobacilli lebeni_, and _Bacillus caucasina_ and the Long Bacilli
+of Mazun, in (1) not growing in ordinary media; (2) producing a large
+amount of lactic acid in milk; (3) producing, besides coagulation of
+casein and splitting up the sugar of milk into lactic acid, no other
+change in milk; (4) not producing any indol, nor peptone, nor
+saponification of fat, nor formation of any gas.
+
+"3. It differs from the above by showing peculiar pink-stained granules,
+when stained with methylene blue and showing peculiarly convoluted
+chains in glucose agar.
+
+"4. The importance of the organism lies in the fact that, as in the case
+of _Bacillus bulgaricus_, it kills all pathogenic non-sporing germs and
+also destroys all proteolytic gas-forming bacilli in milk."
+
+In the account of these investigations the following table is given,
+showing the amount of lactic acid produced by different lactic acid
+bacilli in one litre of milk, in terms of lactic acid--the culture
+being kept at 37 deg. C.
+
+  +--------------+-------+-------+-------+-------+-------+-------------------+
+  | Name of the  | After | After | After | After | After |                   |
+  |  Bacillus.   |   24  |   48  |  72   |  96   |  a    |    Remarks        |
+  |              | Hours.| Hours.| Hours.| Hours.| Week. |                   |
+  +--------------+-------+-------+-------+-------+-------+-------------------+
+  | B. lactis    |  1.8  |  ...  | 10.08 |  ...  |  ...  | Observed by       |
+  |  aerogenes    |       |       |       |       |       |  Hall and Smith   |
+  |              |       |       |       |       |       |                   |
+  | B. coli      |  1.8  |  ...  |  4.77 |  ...  |  ...  | Observed by       |
+  |  communis    |       |       |       |       |       |  Hall and Smith   |
+  |              |       |       |       |       |       |                   |
+  | B.           | 12.8  | 16.5  | 20.2  |  ...  | 22    | Observed by       |
+  |  bulgaricus  |  -.4  |  -.4  |  -.4  |  ...  |  -.4  |  Gabriel Bertrand |
+  |              |       |       |       |       |       |  and Weisweller;  |
+  |              |       |       |       |       |       |  the initial      |
+  |              |       |       |       |       |       |  acidity of the   |
+  |              |       |       |       |       |       |  milk was 4       |
+  |              |       |       |       |       |       |                   |
+  | Matzoon Long | 10.8  | 12.   |  ...  |  ...  |  ...  | Observed by       |
+  |  staebschen B.|       |       |       |       |       |  Dueggeli          |
+  |              |       |       |       |       |       |                   |
+  | Strepto-     |2.61[34]  ...  |  ...  |  ...  |  ...  | Observed by       |
+  |  bacillus    |       |       |       |       |       |  Rist and Khoury  |
+  |  lebenis     |       |       |       |       |       |                   |
+  |              |       |       |       |       |       |                   |
+  | Streptothrix | 10.8  |  1.08 | 11.25 | 11.70 | 18.5  | Med. Coll.,       |
+  |  dadhi       |       |       |       |       |       |  Calcutta         |
+  +--------------+-------+-------+-------+-------+-------+-------------------+
+
+In different parts of the world sour milk is consumed in great
+quantities, and it is stated by Metchnikoff[35] that the chief food of
+the natives of tropical Africa consists of soured milk, and in Western
+Africa in the region south of Angola, the natives live almost entirely
+on this product, there being a difference in the curdled milks produced
+according to the nature of the microbial flora which is introduced.
+
+It is stated[36] that in Servia, Bulgaria,[37] and Roumania there were
+5000 centenarians living in 1896, and while many reasons are advanced
+for such an abnormal condition of affairs, it seems fairly certain that
+the sole reason why people in these districts live to such great ages is
+because of their mode of living and the fact that they live very largely
+on soured milk. The hygienic conditions throughout these countries are
+not such as would give the population in the towns and villages any
+special advantages in the prolongation of life, and while it may be
+stated that a pastoral and agricultural life are likely to contribute to
+longevity, these conditions would not account for a general tendency to
+live long in the countries referred to, more than in any other
+agricultural area. There are many countries throughout the world in
+which the pastoral and agricultural existence is general, but it has
+not been shown that in these countries life is prolonged. Hence the
+conclusion has been forced upon investigators that the reason is to be
+found not in the pastoral conditions, but in the habit which has existed
+from time immemorial of consuming sour milk as a principal article of
+diet.
+
+There is no curtailment of the use of fermented milks in Eastern Europe,
+and the methods of preparation at the present day are those which have
+been carried out from time immemorial. A local observer states that in
+Bulgaria yoghourt is made in nearly every household, especially in the
+spring and summer. The method of preparation is very simple: The milk is
+boiled until a quarter of its volume has evaporated, it is then cooled
+to 45 deg. C. and the ferment added. This ferment is a portion of the
+yoghourt of good flavour and is called "Maya" or "Zakvaska." The vases,
+a kind of earthenware pot, are enveloped in woollen stuff or sheepskin
+and placed in a warm place near the chimney. In ten hours the yoghourt
+is made, and it is preserved in a cold place. The great reputation that
+the yoghourt has acquired in Western Europe has caused this "Maya" to
+become an article of commerce. It is sent out by rail hermetically
+sealed in tinplate boxes. According to a Sophia chemist, the "Maya" is
+employed in the following manner: For a litre of milk it is necessary to
+take about 10 gr. of the ferment. This ferment is diluted with three
+times the amount of water and put into a bowl previously heated with hot
+water and dried. Into this bowl the milk, previously boiled and cooled
+to a temperature of 75 deg. to 50 deg. C., is poured; it is then covered
+over and put in a temperature of about 30 deg. C., and, in default of a
+stove of constant temperature, the bowl is wrapped round with flannel or
+a plaid, and left to curdle for eight to ten hours. It is then ready for
+consumption. During winter, curdled milk keeps for several days, and in
+summer it becomes sour in from twelve to twenty-four hours.
+
+A similar food to the yoghourt is prepared in the Balkan mountains from
+sheep's milk under the name of "Urgoutnik."[38] The milk is poured into
+a goat-skin or sheepskin bag, and a little of the fermented milk added,
+and is then left for some hours in a warm place. The milk consumed is
+replaced by a fresh supply. In some of the Balkan countries, they are
+not content with the fermentation of the milk, they add a little alum,
+which, under the name of "typsa," is well known for this purpose. The
+milk attains such a solid consistency that it can be put into a cloth
+and carried to market.[39]
+
+The various forms of sour milk which have been described in the
+foregoing pages may be said to be of the traditional kind, and with the
+light of modern knowledge, it has been possible to determine exactly
+what constitutes the active principle in use in the milk consumed in
+these countries, and, as we shall see, this principle has been applied
+so that, at the present day, a pure fermented milk may be obtained in
+any country, and there is every reason to believe that should such be
+adopted as a general article of food, it would contribute to the
+prolongation of human existence.
+
+It is due to Metchnikoff, of the Pasteur Institute, that so much
+prominence has been given to the use of fermented milks. He gave it as
+his opinion[40] that senility was caused partly by auto-intoxication or
+by the poison derived from putrefactive micro-organisms which inhabit
+the digestive track. These organisms increase with age, and under
+certain unhealthy conditions multiply enormously, particularly in the
+large intestine. Having arrived at this knowledge, Metchnikoff set to
+work to devise some means of combating the influence of these harmful
+microbes, and set up the hypothesis that the tendency to longevity which
+is exhibited in Eastern countries is due to the consumption of lactic
+acid organisms in the shape of soured milk. These organisms are more
+powerful than those of a putrefactive character and inhibit their
+growth.
+
+"In the presence of such facts," says Metchnikoff, "it becomes
+exceedingly important to find some means of combating the intestinal
+putrefaction which constitutes so incontestable a source of danger. Such
+putrefaction is not only capable of producing diseases of the digestive
+tube--_enteritis_ and _colitis_--but even of becoming a source of
+intoxication of the organism in its most varied manifestations.
+
+"It is some years since I proposed to combat intestinal putrefaction and
+its injurious consequences by means of lactic ferments. I thought the
+acidity produced by such microbes would be much more effective in
+preventing the germination of putrefying microbes than the small
+quantity of acids produced by _Bacillus coli_. On the other hand, I had
+no illusion as to the difficulty sure to be encountered in any effort to
+introduce lactic microbes into the intestinal flora which has been
+preoccupied by a multitude of other microbes. To make surer of the
+result, I chose the lactic microbe, which is the strongest as an acid
+producer. It is found in the _yahourt_ (yoghourt), which originates in
+Bulgaria. The same bacillus has also been isolated from the _leben_ of
+Egypt; and it is now proved that it is found in the curdled milk of the
+whole Balkan peninsula, and even in the Don region of Russia."[41]
+
+It is a short step from considerations like these to the adoption of the
+_Bacillus bulgaricus_ as the most potent of the various lactic organisms
+which have been examined, and which is likely to play such an important
+role in the destiny of the human race. The _Bacillus bulgaricus_ may
+claim to be the Bacillus of Long Life.
+
+
+
+
+CHAPTER III
+
+THE CHEMISTRY OF MILK
+
+
+_The Composition of Milk._--Like all other organic substances, or those
+built up in connection with the life processes of plants and animals,
+milk is of complex composition. It is also very liable to change--every
+one is acquainted with its tendency to "go bad." This instability is
+more or less inherent in all highly organised chemical compounds, and,
+indeed, it seems to be necessary that the materials used in growth and
+nutrition should be very plastic in a chemical sense, in order, _e.g._,
+that the constituents, say of a plant, may easily be transformed into
+the substances of the body of the animal which feeds on it.
+
+The perishable nature of milk--the food of young and growing animals--is
+therefore essential, so that it may be changed easily into the blood,
+bone, muscle, etc., so abundantly required in the early stages of
+existence.
+
+Milk is a complete food, and, therefore, naturally it is not a simple
+chemical compound, but a mechanical mixture of a number of substances.
+The present state of chemical knowledge on the subject does not permit
+of its composition being given in detail, but for practical purposes,
+such as those of measuring its purity and food value, this is not
+necessary.
+
+A proximate analysis, in which, at least, some of the ingredients are
+lumped together, is sufficient, and has been adopted everywhere by
+analysts. On this basis the average composition of cows' milk may be
+stated as follows:
+
+                       Per cent.
+  Water                  87.50
+  Fat                     3.50
+  Casein and albumen      3.65
+  Milk sugar              4.60
+  Ash                     0.75
+                          ----
+                        100.00
+                        ------
+
+The constituents other than water added together form the "total
+solids," and they amount to 12.5 per cent.
+
+                       Per cent.
+  Water                  87.5
+  Total solids           12.5
+                         ----
+                        100.0
+                        -----
+
+  [Illustration: THE CONSTITUENTS OF MILK
+  In the illustration, a pint of milk is shown in a glass
+  jar, and the various percentages of water, casein, sugar,
+  ash, albumen, and fat, which make up its constituent
+  parts, are shown in separate bottles, the percentage of
+  each being stated beneath.]
+
+Milk varies a good deal in composition; the different breeds of cows
+give varying qualities. The Short-horn gives large quantities of milk of
+rather poor analysis, while the Jersey yields smaller proportions of
+very rich milk. During the period of lactation (the time which has
+elapsed since the cow gave birth to a calf), care in milking, food,
+health, etc., all have an effect on the quality of the milk.
+
+The limits of variation may be stated as follows:
+
+                            Per cent.     Per cent.
+  Water                       87.5    to    82.5
+  Fat                          2.5     "     6.0
+  Casein and albumen           3.0     "     4.5
+  Milk sugar                   3.5     "     6.0
+  Ash                          0.6     "     0.8
+
+These figures are extreme, and it is very seldom indeed that either the
+minimum or maximum is reached. Indeed, by the regulation laid down under
+Clause 4 of the British Sale of Food and Drugs Act of 1899, when the
+percentage of solids not fat falls below 8.5 per cent., and fat under 3
+per cent., it is assumed that the milk has been adulterated. This
+regulation is a perfectly just one. While genuine milk may, in rare
+instances, show figures as low as 7.1 per cent. of solids not fat, or
+2.5 per cent. of fat, the right can hardly be claimed of supplying such
+an abnormal article to the public as milk of proper quality, and the
+dairyman who understands his business, and wishes to deal fairly with
+his customers, can, by attention to the conditions enumerated above
+which influence the composition of milk, entirely avoid the production
+of such a low-grade article.
+
+In the nutrition of both plants and animals large quantities of water
+are needed. The solids must be supplied in solution or dissolved in the
+assimilative processes, and this cannot take place without water, which
+also conveys the dissolved solids to the various parts of the economy,
+and in the case of animals removes waste materials. For the most part,
+water passes through the body unchanged, but a certain proportion unites
+chemically with the food materials and assists in their digestion. It is
+therefore not surprising that seven eighths of milk is composed of
+water. Blood contains a similar proportion, and this agreement
+emphasises the fact that milk is a perfectly balanced food.
+
+The fat of milk, which yields cream and butter, differs in some
+important respects from other fats. Like these, it is made up chiefly
+of stearin, palmitin, and olein, but, in addition, it contains an
+abnormally large proportion of compounds of certain of the volatile
+fatty acids. It is these which give to butter its agreeable flavour. By
+the methods of Duclaux, the following is the approximate composition of
+butter fat:
+
+                                              Per cent.
+  Stearin, palmitin, olein, and traces of
+     myristin and butin                         91.50
+  Butyrin                                        4.20
+  Capronin                                       2.50
+  Caprylin, caprinin, and traces of laurin       1.80
+                                                -----
+                                               100.00
+                                               ------
+
+Myristin occurs in nutmegs; butyrin in another combination flavours
+pineapples and rum; caprinin is found in cocoanut fat, mutton fat, and
+in the offensive odour given off by the goat (from which the name is
+derived); caprylin is a by-product of alcoholic fermentation, and also
+occurs in cocoa fat; laurin is found in sweet bay; from which it is
+evident that there are some curious relationships in flavouring
+materials.
+
+Fats are very concentrated foods, furnishing a large amount of energy to
+the body. At one time they were classed together with starch, sugar,
+and other carbohydrates as heat-producers, but the distinction which
+was drawn between the kinds of food which were thought solely to keep up
+the temperature of the organism, and those which produced force in work
+and other forms of bodily energy, has broken down, and by direct
+experiment has been found not to exist. It is usually calculated that
+one part of fat is equal in food value to about two and a quarter parts
+of any of the other carbohydrates. Milk fat or butter is more digestible
+than almost any other fat, and its importance therefore can readily be
+realised. All the above constituents of milk fat are composed of
+different proportions of carbon, hydrogen, and oxygen, but milk also
+contains minute quantities of lecithin, a fat containing phosphorus in
+addition. Lecithin is also found in the brain and nerve material of
+animals, in the yolk of egg, and in several plants.
+
+The nitrogenous constituents of milk--casein and albumen--are usually
+estimated together, and they are reckoned as of equivalent food value.
+The name protein is very commonly applied to the total of these bodies
+in milk, or other animal and vegetable foods. They are composed of
+different proportions of carbon, hydrogen, oxygen, and nitrogen, with
+small quantities of sulphur, while casein contains phosphorus in
+addition. Albumen exists to the extent of about 0.6 per cent. in milk.
+It is very similar in properties to egg albumen. The coagulum which
+forms on the surface of milk when boiled is largely composed of albumen.
+Casein is combined with, and kept in solution by, lime, soda, and
+calcium phosphate, and its amount averages a little over 3 per cent.
+
+The remarkable property possessed by rennet, of curdling or coagulating
+casein, is well known; rennet is an extract from the stomach of the
+calf, and similar principles are present in the stomachs of man and
+other animals, so that the coagulation of milk is the first process in
+its digestion. If milk is gulped down in large quantities it is apt to
+coagulate in lumps, and digestion is much interfered with, but if it is
+taken hot and slowly, it coagulates in small pieces which are readily
+attacked by the gastric juice, and milk is then one of the most
+assimilable of foods.
+
+Nature provides that the milk for young animals is supplied in finely
+divided streams, so that coagulation takes place in the best possible
+way.
+
+The proteids are the most important constituents of food; they are
+abundant in the blood, and build up the muscles, brain, nerves, and
+other bodily structures.
+
+Besides these mentioned, milk contains traces of another proteid of
+similar composition called globulin.
+
+The sugar of milk is not found anywhere else. It is a carbohydrate like
+cane and grape sugar--that is to say, the hydrogen and oxygen they
+contain are in the same relative proportions as in water. Milk sugar is
+not so soluble or so sweet as the other sugars. It does not ferment with
+ordinary yeast, but certain special yeasts which are made use of in the
+preparation of keffir, koumiss, etc., have the power of transforming it
+into alcohol. Its most remarkable property, however, is the facility
+with which, under the influence of certain bacteria, it is changed into
+lactic acid.
+
+Every one is familiar with the souring of milk, but perhaps it is not so
+generally known that there are great differences in the results obtained
+in accordance with the conditions under which the souring takes place.
+The skilled butter-maker, by keeping the milk in a cool and cleanly
+dairy, obtains a sour milk of a characteristic and agreeable aroma and
+taste, which beneficially affect the flavour of the butter produced. On
+the other hand, if milk is kept in hot and dirty surroundings, the
+development of acidity is accompanied by different bad tastes and
+odours, and it becomes unfit for use as a food. In the first case, the
+conditions are favourable to the maximum production of the lactic acid
+bacteria, and these occupy the field, and largely prevent the
+development of the other bacteria which are present--the survival of the
+fittest in the struggle for existence. In the second case, the impure
+surroundings swarm with the germs of many kinds of putrefactive
+bacteria, and the high temperature assists these to gain the upper hand.
+Again, the survival of the fittest, in the particular conditions. Even
+in cool and cleanly surroundings injurious taints may develop,
+especially if the milk has previously been subjected to a journey by
+road or rail, as is the case in the modern creamery system, where the
+farmers deliver their milk to a central creamery, where it is made into
+butter. In such establishments it is the regular practice to kill the
+germs, lactic and others, existing in the milk, by heating it to a high
+temperature. This process is called pasteurising, after the great French
+chemist and bacteriologist who invented it. Pure lactic cultures are
+added to the pasteurised milk, and the souring process is under exact
+control, with the result that butter of uniform flavour and quality is
+produced. The same method is made use of in making the special sour milk
+described in this book, with, of course, modifications in the apparatus
+employed, to suit the smaller scale in which the manufacture is
+conducted.
+
+The ash is the mineral matter which is left when milk, previously dried,
+is burnt in a crucible. It is a complex mixture, and, as we have seen,
+it amounts to about 0.7 per cent. of the milk. The process of burning
+destroys all the organic matter, and, at the same time, alters somewhat
+the state of combination of the inorganic or mineral elements. Attempts
+have been made from the analysis of the ash to reconstitute the
+composition of the mineral matter as it exists in the milk. The best
+known is that of Soldner, and the following is his calculation:
+
+                                             Per cent.
+  Sodium chloride                              10.62
+  Potassium chloride                            9.16
+  Monopotassium phosphate                      12.77
+  Dipotassium phosphates                        9.22
+  Potassium citrate                             5.47
+  Dimagnesium citrate                           3.71
+  Magnesium citrate                             4.05
+  Dicalcium phosphate                           7.42
+  Tricalcium phosphates                         8.90
+  Calcium citrate                              23.55
+  Calcium oxide, in combination with casein     5.13
+                                              ------
+                                              100.00
+                                              ------
+
+The presence of citrates will be noted in this analysis. Citric acid,
+which gives to lemons their acidity, and is also found in other fruits,
+has been proved to exist in milk to the extent of about 0.2 per cent.
+When alkaline or earthy citrates are burnt or oxidised in the blood, the
+citric acid is destroyed, and corresponding carbonates remain. No doubt
+the function of citrates in milk is to furnish to the body the earthy
+and alkaline carbonates which are required in certain of its parts.
+
+The mineral constituents of milk have many important functions to
+perform in the building up and nutrition of the bodily organism.
+Phosphate of lime is the principal constituent of the skeleton, and the
+blood must be richly supplied with the alkalies, earths, and acids which
+are comprehended in the ash.
+
+Milk contains traces of many other substances, the most important of
+which are several enzymes which assist in its digestion.
+
+_General Properties of Milk._--The appearance of milk is known to every
+one; it ought to be a pure white opaque liquid, but very generally it is
+tinted a cream colour with anatto to give it an added appearance of
+richness. The average specific gravity is about 1.031; or, to put it
+another way, while a gallon of pure water weighs exactly 10 lbs., a
+gallon of milk weighs 10 lbs. 5 oz. It freezes at 31 deg. F. and boils at
+about one third of a degree higher than water.
+
+When milk is examined under the microscope, the fat is found to be
+distributed through it in a multitude of minute globules varying in size
+from 1/16,000th to 1/25,000th part of an inch, and occasionally they are
+much smaller and also much larger.
+
+Fig. 1 is a micro-photograph showing the fat globules in whole milk.
+Fig. 2 is a micro-photograph of separated milk, and Fig. 3 a
+micro-photograph of cream, all under high magnification (450 diams.);
+from these figures the comparative number of fat globules present may be
+seen.
+
+  [Illustration: FIG. 1.--Micro-photograph of a Drop of
+  Whole Milk, showing distribution of fat globules.
+  (Magnified 450 diams.)]
+
+  [Illustration: FIG. 2.--Micro-photograph of Separated
+  Milk, showing the almost complete absence of fat globules
+  as compared with whole milk. (Magnified 450 diams.)]
+
+  [Illustration: FIG. 3.--Micro-photograph of Cream, showing
+  agglomeration of fat globules. (Magnified 450 diams.)]
+
+Fats distributed through a watery liquid in this finely divided
+condition form together what is called an emulsion, in which the
+particles of fat are kept apart by surface tension. The specific gravity
+of milk fat averages 0.93, and compared with water weighing 10 lbs., a
+gallon of fat would weigh 9 lbs. 5 oz. It is thus considerably
+lighter than the other constituents, and when milk is left at rest, the
+fat globules gradually rise to the top and float there, forming cream.
+The difference in specific gravity between cream and milk is taken
+advantage of in the mechanical separator, now so much used, and which
+makes such a thorough separation between the two. Cream is an article of
+the most varied composition, according to the ideas of the person who
+produces it, but it ought to contain at least 20 per cent. of butter
+fat, and may be made with a much larger percentage if necessary. When
+cream is agitated in a particular way, as by churning, the surface
+tension of the particles is overcome, and they run together into a mass
+which forms butter.
+
+The casein of milk is not held in solution in the ordinary sense, but in
+a peculiar state of suspension called the colloidal condition,
+practically the whole of it remaining behind when milk is filtered
+through clay filters.
+
+It is this state of suspension of the casein which makes milk opaque,
+but the opacity is considerably increased by the emulsified fat.
+
+The coagulation of the casein in milk by the addition of rennet has
+already been referred to. Acids, either mineral or organic, also
+precipitate it in the form of flakes. Skimmed milk is now largely used
+for the preparation of casein by this method, and the washed and dried
+precipitate is used very extensively in the arts for such varied
+purposes as the manufacture of billiard balls, paints, cements, etc.
+
+The clear liquid which separates when milk is curdled with rennet is
+called whey, and contains the milk sugar and mineral salts. The sugar is
+manufactured from it on a limited scale, and is used as an ingredient in
+infant foods, and as a convenient medium in certain medical
+preparations. In Sweden a kind of cheese is made from whey, but the
+great bulk of it everywhere is used for feeding pigs.
+
+The comparative composition of different varieties of milk is given in
+the following table:
+
+  -------------------------------------------------------------------------
+             Human   Cow   Buffalo  Goat  Sheep   Mare   Ass Reindeer Whale
+  -------------------------------------------------------------------------
+  Water      88.32  87.75   82.57  86.34  81.08  90.38  90.30   67.7  60.47
+  Fat         3.43   3.40    7.63   4.25   7.67   1.00   1.30   17.1  20.00
+  Protein     1.55   3.50    4.69   4.40   6.08   1.98   1.80   10.9  12.42
+  Milk Sugar  6.44   4.60    4.30   4.26   4.26   6.28   6.20    2.8   5.63
+  Salts       0.26   0.75    0.81   0.75   0.91   0.36   0.40    1.5   1.48
+  -------------------------------------------------------------------------
+  Total     100.00 100.00  100.00 100.00 100.00 100.00 100.00 100.00 100.00
+  -------------------------------------------------------------------------
+  Specific   1.032 1.0315   1.033  1.033  1.038  1.034  1.033   ...   ...
+   Gravity
+  -------------------------------------------------------------------------
+
+  [Illustration: FIG. 4 is a photograph of two Petri dishes,
+  which have been inoculated with ordinary milk (A), and
+  milk that has been subjected to sterilisation (B). The
+  whitish bacterial colonies on A are due to enormous
+  numbers of organisms, while B is quite free from such
+  growth.
+
+  For the production of a reliable lactic food, it is
+  essential that certain precautions as to the treatment of
+  the milk, and the maintenance of a suitable temperature
+  during the growth of the lactic bacteria, should be
+  observed.
+
+  In the first place, milk immediately after extraction from
+  the cow contains only a few organisms, but these multiply
+  so rapidly that in a few hours the bacterial content may
+  amount to many millions per ounce. In preparing a pure
+  culture of any specific organism, then, care must be taken
+  to destroy all the bacteria that have accidentally found
+  their way into the milk, inoculating with the organisms it
+  is desired to cultivate. This is best accomplished by
+  heating the milk to the boiling-point of water for about
+  thirty minutes, by which time almost all the undesirable
+  bacteria have been killed.]
+
+The milk of the cow differs a good deal from human milk, and where the
+former is used for the feeding of children it is usual to add milk sugar
+to it, and otherwise alter it to bring its composition more in harmony
+with the human article. The high concentration of the milk of the
+reindeer and the whale is noteworthy. Perhaps this may be due to the low
+temperature conditions in which these animals live, necessitating strong
+nutriment to enable their young to make proper progress in growth and
+development. On the other hand, the milk of the ass is poor in quality,
+and probably on this account it is more readily assimilated by those of
+weak digestion, to whom it is sometimes recommended. Goats' milk is
+richer than either cow or human milk, and its nourishing properties are
+well known. The goat is usually free from tuberculosis and other
+diseases which affect the cow, and its milk is therefore a very safe
+article to use.
+
+_The Analysis of Milk._--While the analysis of milk can only be made by
+a competent chemist, there are a number of simple tests and observations
+by which any intelligent person can obtain a fair idea of its quality.
+The taste and smell afford some guide, as also the general appearance.
+To judge of the latter, place some of the milk in a tumbler or other
+clear glass vessel. If the milk is of good quality it will be quite
+homogeneous and opaque. Any flocculent matter indicates either disease
+in the cow or that the milk is old and bacteria have multiplied in it
+and altered its composition. When the milk has stood long enough for the
+cream to rise freely, the latter should form a perfectly homogeneous and
+strongly defined layer on the top. The quantity of cream may be measured
+in a creamometer, which consists of a small glass cylinder graduated at
+the top (Fig. 5). It is filled with milk to the top graduation line, and
+when the cream has risen, the percentage quantity of the latter which
+has separated can be taken off.
+
+  [Illustration: FIG. 5. The Creamometer]
+
+The colour should be like that of porcelain, but, as already stated, it
+is a common thing for the dairyman to add a small quantity of anatto or
+an aniline dye of a similar shade, to give the milk a rich creamy tint.
+If the milk is of a reddish colour this may be caused by blood from the
+udder, although certain foods, such as beets, mangels, and carrots
+sometimes give a similar tint. The milk given by cows immediately after
+calving is called "colostrum" or "biestings," and is of a yellow or
+yellow-brown colour. It is much thicker than ordinary milk, and
+coagulates in boiling.
+
+In dirty byres in which care is not taken in milking, quite considerable
+quantities of hairs, pieces of manure, and other filth may get into the
+milk. Usually the milk is strained by the dairyman, but sometimes this
+is omitted or carelessly done. To test for dirt, a ribbed glass funnel
+is useful. Get a piece of the finest muslin about twice the diameter of
+the funnel, fold over twice, so that it becomes one quarter of its
+original size; open one of the sections and place in the funnel; pass
+the milk into this. It will run through quickly and some water may be
+run into the funnel to clear away the last traces of milk. The filter
+cloth can then be opened out and any dirt retained will become visible.
+The apparatus is shown in Fig. 6.
+
+  [Illustration: TESTING-GLASS FOR EXTRANEOUS MATTER IN
+  MILK.
+
+  FIG. 6.--A piece of muslin is folded as shown and a
+  measured quantity of milk is passed through the funnel;
+  from the sediment left in the muslin, the percentage of
+  extraneous matter may be arrived at.]
+
+If a glass funnel is not available, a very small jelly bag can be made
+of fine gauze and used in the same way. The washing water should be used
+in small quantities and directed to concentrating the dirt in the apex
+of the bag. After washing, the latter can be turned outside in, to
+permit of readier examination of the dirt. The bag should be well
+washed in cold water, then boiled and dried, and is then ready for
+future use.
+
+The acidity of milk is a very useful guide to its age. Milk has the
+curious property of being "amphoteric," _i.e._, it is both slightly acid
+and slightly alkaline when fresh. As its age increases, however, so does
+its acidity, and at a rate varying with the temperature and moisture
+contents of the atmosphere in which it is placed. Old and acid milk is
+heavily contaminated with bacteria, a proportion of which are likely to
+be injurious to health.
+
+  [Illustration: FIG. 7. Lactometer and Test Tube]
+
+The simplest method of testing the acidity is to procure a few little
+books of blue and red litmus test papers, and these can be had from any
+philosophical instrument maker or laboratory furnisher. The strips of
+test paper are torn out and dipped in the milk. When the milk is quite
+fresh it will, owing to its amphoteric condition, change the red litmus
+paper slightly blue, and the blue litmus paper slightly red. Old milk
+changes blue litmus paper to a bright red because of its decided
+acidity.
+
+The above tests do not indicate if the milk is poor or rich, but this
+can be determined by the lactometer, an instrument for ascertaining in a
+simple way the specific gravity. The lactometer is shown in Fig. 7.
+
+It is graduated usually from 25 deg. to 36 deg., corresponding to specific
+gravities 1.029 to 1.038. It is graduated to degrees and half degrees.
+Sometimes a thermometer is combined with the instrument. The specific
+gravity rises as the temperature is lowered and decreases with increase
+of temperature, so that it is important to make the test at the figure
+at which the lactometer was graduated, which is usually 60 deg. F. Failing
+this, an allowance has to be made for higher or lower temperatures. The
+milk to be tested is well mixed, and placed in a deep vessel, and the
+lactometer placed in it, holding it at first at an angle. It stands
+upright and remains deeper or higher according to the specific gravity.
+The reading is taken on the stem at the level of the milk. As the latter
+is drawn up a little round the stem, about a half degree should be added
+on to get the true figure. Thus, if the apparent reading is 31, the true
+reading may be taken as 31.5. This is the average figure for good milk,
+corresponding to a specific gravity of 1.0315; anything above this is
+all to the good. Lower readings mean inferior quality, the latter being
+proportionate to the lowness of the readings. The tests are most
+conveniently made in a glass cylinder (Fig. 7), which may be purchased
+with the lactometer. As there are many inaccurate instruments in the
+market, it is necessary to go to a reputable maker, because an
+unreliable lactometer is worse than useless.
+
+The following table gives, in a condensed form, the allowances to be
+made when the temperature is above or below the standard (60 deg. F.):
+
+  ------------+----------------------------------------------------------
+  Temperature.|               Reading of Lactometer.
+  ------------+------------------------------------------------------------
+     Degs. F. |
+       40     | 23.5 24.5 25.5 26.4 27.3 28.2 29.1 30.0 31.0 31.9 32.8 33.7
+       45     | 23.8 24.8 25.9 26.8 27.8 28.6 29.3 30.4 31.3 32.3 33.2 34.2
+       50     | 24.1 25.1 26.1 27.0 28.0 29.0 29.9 30.9 31.8 32.8 33.7 34.7
+       55     | 24.5 25.5 26.5 27.5 28.5 29.5 30.4 31.4 32.4 33.4 34.3 35.3
+  ------------+------------------------------------------------------------
+       60     | 25.0 26.0 27.0 28.0 29.0 30.0 31.0 32.0 33.0 34.0 35.0 36.0
+  ------------+------------------------------------------------------------
+       65     | 25.5 26.6 27.6 28.7 29.6 30.7 31.7 32.8 33.8 34.8 35.8  ...
+       70     | 26.1 27.2 28.2 29.3 30.2 31.3 32.4 33.4 34.5 35.5 36.5  ...
+       75     | 26.8 27.8 28.8 29.9 30.8 32.1 33.1 34.2 35.2 36.3  ...  ...
+       80     | 27.4 28.4 29.5 30.7 31.6 32.8 33.9 35.9 36.1  ...  ...  ...
+  ------------+------------------------------------------------------------
+
+Thus if the thermometer indicates 40 deg. F., and the lactometer 29.1 deg.,
+the true reading at the standard temperature of 60 deg. F. is 31 deg.,
+corresponding to a specific gravity of 1.031. Intermediate figures can
+readily be averaged. Care should be taken to wash the lactometer with cold
+water under the tap, as otherwise the milk will dry on it and render it
+inaccurate.
+
+
+
+
+CHAPTER IV
+
+HANDLING OF MILK
+
+
+MODERN DAIRY PRACTICE
+
+As we have seen, the dairy industry is a very ancient one, and has been
+intimately associated with the development of civilisation.
+
+Within historical times dairying has always formed a prominent feature
+in connection with agriculture, and the use of milk in one form or
+another has been common to every civilised nation.[42]
+
+The greatest progress, however, in the study of milk has taken place
+since about the year 1890, at which time the dairy industry seems to
+have attracted the general attention of food specialists and scientific
+investigators throughout the world. Since then it has been considered
+worth while to enact laws in different countries with regard to the
+regulation and control of the milk supply.
+
+Since 1903 there has been an International Dairy Federation formed, and
+it has held conferences at Brussels, Paris, The Hague, and Buda-Pest,
+and in 1911 it will hold a conference in Stockholm. The Federation was
+started in a very humble way in Brussels, and owes its origin, to a
+large extent, to a distinguished Belgian agriculturist, Baron Peers of
+Oostcamp, Bruges; but at the present day a general committee composed of
+representatives of nearly every civilised nation has been formed, and
+delegates from such countries attend the Congresses, which are held
+every two years. The literature which has arisen out of these
+International Congresses has been disseminated in different countries,
+and has been instrumental in placing the dairy industry on a thoroughly
+scientific basis.
+
+_Milk Supply of the United Kingdom._--The milk supply of the United
+Kingdom has steadily grown from year to year, and in relation to the
+population works out at fifteen gallons per head. The manner in which
+these figures are arrived at is shown in the following estimate:
+
+  The population of the United Kingdom is now about
+  45,500,000. The number of cows or heifers in calf or in
+  milk in June, 1909, was 3,360,600; the number in 1910 was
+  probably about 4,400,000.
+
+  Of these about 300,000 were heifers that had not yet
+  produced any milk. The actual milking class, therefore,
+  comprised about 4,100,000 cows and heifers; of these,
+  about 600,000 were heifers that calved in the winter and
+  spring of 1909-10, and 300,000 were heifers that calved in
+  the summer and autumn of 1910. The number of cows that
+  produced two or more calves may be taken to be about
+  3,200,000; of these about 600,000 should have produced
+  their second calf in the winter and spring 1909-10, and
+  would be milked as heifers in the summer and autumn of
+  1910; the number of mature cows from which a full season's
+  supply of milk was obtained during the twelve months from
+  June 5, 1909, to June 4, 1910, was apparently about
+  2,600,000. A large quantity of milk is yielded during the
+  year by cows sold or lost during the twelve months before
+  the census. Possibly ten per cent. of the milk produced in
+  the twelve months from June, 1909, to June, 1910, was
+  yielded by cows that were sold or lost before the census
+  of June, 1910.
+
+  It is estimated that the 3,200,000 cows (including the
+  600,000 that up to the winter of 1909-10 were heifers)
+  produced, on the average, 44 cwts. (480 gallons) of milk
+  per head in the twelve months from June 5, 1909, to June
+  4, 1910; the 300,000 heifers that calved in the summer and
+  autumn, 30 cwts. (330 gallons) per head; the 600,000
+  heifers that calved in the winter and spring of 1909-10,
+  15 cwts. (165 gallons), making the total quantity of milk
+  produced in the twelve months by cows and heifers on the
+  farms, and that produced calves during the twelve months
+  (June, 1909-1910), 158,800,000 cwts. (1,746,800,000
+  gallons), or about 426 gallons per head, and about 400
+  gallons per head for all the cows and heifers in milk or
+  in calf in 1910. There remains to add the milk yielded by
+  the cows that were sold during the twelve months, and of
+  cows and heifers in feeding pastures that were milked
+  during the twelve months, June to June, 1909-10, and which
+  probably formed one tenth of the whole supply, making the
+  total supply for the twelve months 176,444,000 cwts., or
+  1,940,884,000 gallons. This equals 2 tons, or 440 gallons
+  per head, crediting the whole supply to the 4,400,000 cows
+  and heifers in milk or in calf in June, 1910. At 7-1/4d.
+  per gallon the value of milk produced in the United
+  Kingdom in the twelve months was L58,600,000. Including
+  the value at birth of the calves, the total value of the
+  produce of the milk-giving class would be about
+  L62,000,000. The value of the milk, butter, cheese, and
+  cream sold or consumed in farmhouses would be about
+  L48,000,000, or equal to about 24 per cent. of the gross
+  annual income of farmers.
+
+  The average consumption of new milk is about 15 gallons
+  per head of the population. During the twelve months of
+  1911, the quantity required for this purpose will be about
+  682,500,000 gallons, or about 35 per cent. of the total
+  supply; calves will require about 10 per cent. of the
+  supply; the quantity available for butter and cheese will
+  equal about 55 per cent. of the supply.[43]
+
+_The Milk Industry in the United States._--In the United States of
+America, where the habits of the people are somewhat analogous to those
+in the United Kingdom, it is estimated that the milk from five million
+cows is annually consumed, which averages twenty-five and one half
+gallons per year for each person, or equal to an ordinary sized
+tumblerful each day.[44]
+
+Such a vast industry, so intimately associated with the food of the bulk
+of the people, naturally invites the closest study, and, as a
+consequence, the literature on the subject, which has arisen during the
+last twenty years, has been of a voluminous character, not only from the
+point of view of practice, but from that of bacteriology, chemistry, and
+hygiene.
+
+A pure milk supply is essential to health, and it seems unfortunate that
+the ordinary milk producer should, in a great many cases, take up an
+antagonistic attitude to the scientific methods of handling milk. There
+is a body of opinion being created, however, which is likely to alter
+this attitude in the next generation, and this is attributable to the
+fact that so much excellent work has been done at numerous dairy
+colleges and institutes in all civilised countries that the dairy
+industry is emerging from a period of rule-of-thumb procedure to its
+proper place as one of the technical arts.
+
+_Transmission of Disease in Milk._--It is not to be wondered at that the
+handling of milk should now be regarded as a technical business, seeing
+that milk-borne disease is one of the commonest with which we have to
+deal.
+
+The commoner diseases which have been transmitted by milk are scarlet
+fever, typhoid, diphtheria, tuberculosis, sore throat epidemics. Others
+of a more complex character have been traced to the same source of
+infection, and the clearest possible evidence has been furnished of the
+transmission of diseases by means of micro-organisms, which have
+contaminated the milk supply.
+
+It is therefore necessary to watch over the milk from the source of
+supply to its consumption. It is primarily on the farm and in the
+cow-house that methods of handling in a hygienic way should be insisted
+on, as microbial contamination increases at a prodigious rate, and it is
+the early microbe therefore which does the most damage.
+
+The milk in the udder, for all practical purposes, may be assumed to be
+sterile, and the contamination which takes place originates, therefore,
+from external sources.
+
+One of the principal means of infection is from hairs which fall from
+the cow into the milk, and many of which are carriers of dangerous
+micro-organisms.
+
+There is also a certain amount of offensive dirty matter which may fall
+into the milk-pail, and carry with it undesirable germs.
+
+These impurities may, to a certain extent, be eliminated by good
+straining, but a surer prevention is to have the cow-house perfectly
+clean and free from dust, as dust specks are in many cases the vehicles
+of disease germs. Cleanliness is, in fact, the essential feature in
+modern dairying, not only in the cow-house, but in the milking utensils,
+the drainage, etc., and, above all, the milker should be of cleanly
+habits.
+
+The flavours of milk sometimes arise from the absorption of
+evil-smelling gases in the cow-house, or from a peculiar taint from
+certain roots and feeding stuffs, and in such a case it is desirable
+that aeration should take place in a fresh clear atmosphere, so that
+oxygenation may have the effect of eliminating and destroying the
+foreign odours and flavours which may be present. If this process of
+aeration is carried out at blood heat, the result is generally highly
+satisfactory.
+
+_Milk Management._--There have been many excellent tables of rules
+published for the management of dairies in different countries, but they
+are necessarily framed within certain limitations which apply to all.
+The following is an excellent set, which put concisely the conditions
+necessary to be observed in the modern cow-house:
+
+   1. The cow should be sound--no disease should exist in
+        the animal.
+
+   2. The feed should be good and free from aromatic
+        substances. If these aromatic foods are used, they should
+        be employed according to those methods which will not
+        cause odours or flavours to appear in the milk.
+
+   3. The cow should be groomed, and hair about the udder
+        preferably clipped.
+
+   4. The udder should be moistened during milking.
+
+   5. The milker should be a neat, tidy person.
+
+   6. The milker should be free from disease, and should not
+        come in contact with any communicable disease.
+
+   7. The milker's clothes and hands should be clean while
+        milking.
+
+   8. The pail should be sterilised.
+
+   9. The stall should be such as to reduce the amount of
+        disturbance of dust and dirt.
+
+  10. There should be good light, good ventilation, and
+         good drainage in the cow-house.
+
+  11. The cow-house should always be kept clean.
+
+  12. Feeding and bedding, unless moist, should be done
+        after milking.
+
+  13. A dustless milking-room is desirable.
+
+  14. Milk should not stand in the cow-house.
+
+  15. If milk is aerated, it should be done before cooling
+        and in pure air.
+
+  16. The sooner the milk is cooled after milking the
+        better.
+
+  17. Keep the milk as cold as possible when once
+        cooled.[45]
+
+The supply of milk is conducted, to a large extent, by towns' dairies,
+which depend for their supplies upon the dairy farm in the country, and
+it is obvious that a certain period of time must elapse, in the
+generality of cases, before a town's dairy receives its supply in the
+ordinary course, and this constitutes the greatest difficulty in modern
+dairy practice, owing to the liability of the milk to absorb bacteria,
+which during transit may multiply enormously.
+
+The multiplying of bacteria in milk at different temperatures is easily
+demonstrated, and the result of this has been stated in various forms
+many times over. As a graphic means, however, of showing the increase
+that takes place in the numbers of germs present, and the consequent
+product of acidity, the table below by Conn may be given.
+
+The consequent result of the increase in bacteria is the production of
+lactic acid, which produces the souring so familiar in milk which has
+been kept in the household at a high temperature.
+
+  _Numbers of Bacteria per c.cm. in Milk kept at
+             Different Temperatures._
+
+  --------------------------------------------------------------------------
+  Number  In 12   In 12    In 50    In 50 hrs. or at   No. hrs.   No. hrs.
+  at     hrs. at hrs. at  hrs. at   time of curdling   to curdle  to curdle
+  Outset 50deg.F. 70deg.F. 50deg.F. at 70deg.F.        at 50deg.F. at 70deg.F.
+  --------------------------------------------------------------------------
+  46,000 39,000 249,500 1,500,000   542,000,000            190        56
+  47,000 44,800 360,000   127,500   792,000,000.36 hrs.    289        36
+  50,000 35,000 800,000   160,000 2,560,000,000.42 hrs.    172        42
+  --------------------------------------------------------------------------
+
+What actually happens is that the lactic acid is produced by the
+breaking up of the milk sugar, and the appearance of this sourness is an
+indication that a period has been reached in the age of the milk which
+may be described as being--unwholesome.[46]
+
+It is necessary, therefore, for the town's milk dairy to be equipped in
+such a way as to deal promptly with the milk supply.
+
+We have seen that the milk should first of all be aerated at blood heat,
+so as to liberate objectionable odours, after which it should be cooled
+to as low a temperature as possible, by means of well water. When these
+operations have been performed on the farm, milk should be sent as
+rapidly as possible to the distributing towns' dairies, and should be
+transported in refrigerated waggons, cooled preferably with ice, during
+the journey. On arrival at the town dairy, it will be necessary to
+pasteurise the milk--that is to say, the milk should be heated to such a
+temperature as will destroy any pathogenic organisms which may be
+present, and the pasteurising temperature should therefore be in excess
+of the thermal death-point of all such organisms.
+
+Pasteurisation owes its origin to Pasteur, and has become an adopted
+method throughout the dairy industry, and there are many mechanical
+devices termed "pasteurisers" (see Fig. 8) which are used for the
+carrying out of this particular operation. The form of one of these is
+that of a vertical jacketed cylinder with paraboloidal surface, around
+which steam is made to pass, so as to maintain the temperature at about
+176 deg. F. Milk is allowed to flow in at the bottom of the paraboloidal
+surface, and is caught by mechanical agitating arms, which revolve at a
+given speed, and by this action milk is distributed centrifugally over
+the paraboloidal surface, and is forced out by the same action, at the
+top of the apparatus, after being heated.
+
+  [Illustration: PASTEURISER
+
+  FIG. 8.--The milk enters from the bottom and circulates to
+  the top of the inside cylinder, which is paraboloidal in
+  construction. It is heated as it passes through the
+  apparatus, and is discharged at the top at a temperature
+  of 176 deg. F.]
+
+The centrifugal action is sufficient to raise the milk some three to
+four feet, through a tube, and this is taken advantage of so as to cause
+the milk to flow over a conical cooler, described as a primary cooler,
+and in which water is made to circulate. As the hot milk descends over
+the conical cooler it gives up most of its acquired heat to the water,
+and, in practice, is reduced in temperature to within 4 deg. of the
+temperature of the water.
+
+Below this primary cooler is fixed a cooler of the same size and shape,
+which is termed a secondary cooler. In it, brine at a temperature of
+about 35 deg. F. is circulated from a refrigerating machine, and, as the
+milk falls over the secondary cooler, it is cooled to a temperature of
+about 40 deg. F., when it may be looked upon as being pasteurised and free
+from all pathogenic organisms, in which state it will keep for a
+considerable length of time.
+
+It is desirable that the milk should, as soon as possible after the
+cooling takes place, be delivered to the consumers, and be kept under
+cool conditions, either in bottles or in a closed vessel covered over
+with muslin, so as to keep out specks of germ-laden dust.
+
+Briefly speaking, the foregoing is an outline of what is carried on in
+the ordinary dairy practice.
+
+There are many modifications of this practice, such as the introduction
+of regenerative heaters, so as to utilise a portion of the heat of
+pasteurisation, which would otherwise be wasted.
+
+In some cases, again, it is considered necessary to conduct the primary
+and secondary cooling over coolers furnished with mantles, so that the
+atmospheric bacteria which are everywhere present should be shut off
+from the falling milk.
+
+Ordinarily, however, the equipment for a town's dairy consists of:
+
+1. Steam-boiler to generate steam for pasteurising, scalding, etc.
+
+2. Motive power, which may be either a steam-engine, gas-engine, or
+electric motor.
+
+3. Refrigerating machine, which is used for supplying cold brine to the
+secondary cooler. In many cases it is also used for cooling a room in
+which the milk and cream are stored.
+
+4. Milk-receiving tank.
+
+5. Milk-strainer.
+
+6. Pasteurising apparatus, and primary and secondary coolers.
+
+Such a plant is necessary in order to conduct an ordinary town dairy
+business in anything like a hygienic way, and is designed only for the
+handling of milk intended for domestic consumption.
+
+There are times when another plant might be necessary, such as a plant
+for the separation of milk, or for utilising it for the production of
+butter or cheese, such operations being subject to the fluctuations in
+the milk supply.
+
+It is sometimes desirable also to use up an excess of milk for cheese or
+butter-making; hence it is necessary to provide such apparatus as has
+been indicated.
+
+_Preparation of Soured Milk._--The foregoing description has been given
+in some detail, as showing the ordinary practice, and we now come to
+consider how it can be modified so as to provide for the production of
+soured milk. It may first of all be premised that within the next few
+years the preparation of soured milk as an ordinary production of the
+dairy will be universal, and will form a part of the ordinary dairy
+practice. The apparatus, therefore, which is necessary is one of
+considerable interest to all who are engaged in the dairy industry.
+
+As will be seen from the chapter describing the preparation of soured
+milk in the dairy, this process can be conveniently carried on, so as to
+utilise the plant which is at present in general use. The milk can be
+received in the same way, pasteurised and cooled to about blood-heat,
+after which its preparation as soured milk is a very simple matter, and
+only requires a certain amount of careful attention.
+
+For the keeping of soured milk, a cold room cooled by a refrigerating
+machine would be desirable, so as to maintain the fermented milk at a
+low temperature and prevent over-fermentation.
+
+Apparatus has been designed so as to handle soured milk on a large
+scale, and one of the machines is shown on the illustration (see Fig.
+9). It is simply a jacketed cylinder with a cover and an agitating gear.
+The inside of the machine is nickel-plated, and there is an arrangement
+whereby the cooling may be done rapidly, through a coil inside the
+jacket, this coil being connected to the brine circulation of the
+refrigerating machine.
+
+  [Illustration: CONTINUOUS APPARATUS FOR THE PRODUCTION OF
+  LARGE QUANTITIES OF SOURED MILK
+
+  FIG. 9--This apparatus is made by the Dairy Machinery and
+  Construction Company of Shelton, Conn., U S A. The milk is
+  agitated inside a jacketed cylinder, where it is allowed
+  to incubate at about blood heat. The milk can be rapidly
+  heated and also rapidly cooled by means of this
+  apparatus.]
+
+The machine is filled with milk containing three per cent. of fat, which
+has been previously pasteurised to about 190 deg. F., and cooled down to
+about 90 deg. F.; at this point the pure culture of _Bacillus bulgaricus_
+is introduced, and the agitator is kept working, so as to mingle it
+thoroughly with the milk. The agitator is then stopped until the acidity
+shows a test of 0.9 to 1.0 per cent., when the agitator is again
+started, and cold brine from the refrigerating machine is turned on to
+the cooling pipes, so that the product is thoroughly broken up, and
+cooled down to 40 deg. F.
+
+The milk is then transferred to a bottle-filling machine (Fig. 10),
+poured into bottles and hermetically sealed, after which it is ready for
+consumption. When it has to be kept for any time it should be placed
+in a cold room where there is a temperature not higher than 40 deg. F.
+
+The process, therefore, is a simple one, and lends itself to the
+ordinary dairy business, without involving any great expenditure on
+account of a new plant.
+
+
+
+
+CHAPTER V
+
+THE BACTERIOLOGY OF FERMENTED OR SOURED MILK
+
+
+A CHAPTER FOR STUDENTS
+
+During the last few years much work has been done in investigating the
+action of various classes of organisms--bacteria, yeasts, and
+moulds--upon milk and its products. While, however, the attention of the
+dairyman has been chiefly directed to the propagation of acid-producing
+organisms and the use of pure cultures of lactic acid bacteria in their
+relation to butter and cheese making, a new sphere in micro-biology has
+been disclosed by the study of the effects caused by the combined growth
+of two or more different classes of organisms in milk and the consequent
+production of lactic, alcoholic, and gaseous fermentations. The
+simultaneous occurrence of these fermentative changes is responsible for
+the formation of such beverages as keffir, koumiss, milk-wine, etc. It
+has therefore become essential, in connection with the study of new
+developments in the milk industry, that we should make a more intimate
+acquaintance with the bacteriology of the ferments involved.
+
+_Keffir_ (_kephir_, _kifyr_, _kiafyr_, _kephor_, _kyppe_) is the name
+given to an acid, slightly alcoholic drink, which for many centuries has
+been prepared by the nomadic tribes in the Caucasus. The characteristic
+fermentation is induced by the addition of so-called keffir grains.
+These are yellow or golden-yellow, warty, and furrowed flakes or
+nodules, the former varying in size from that of a rice grain to that of
+a bean, while the latter are often about an inch across and one eighth
+of an inch thick. Bearing in mind the fact that the preparation of
+keffir has been carried on for many centuries, it is not surprising that
+the origin of these grains should be surrounded by myths.
+
+The belief is prevalent among the Mohammedan tribes of the Caucasus that
+keffir grains were, in the first instance, presented by Allah, as a sign
+of immortality, to one preferred tribe. Others hold that, in past ages,
+they were found by shepherds growing on a shrub in the Caucasian
+highlands; while, according to Skolotowski,[47] they were originally
+found adhering to the walls of an oaken vessel used for the preparation
+of airam. This is a soured milk beverage similar to keffir, but
+possessing a weaker alcoholic fermentation, and prepared from goats'
+milk by the addition of pieces of calf's stomach. This would undoubtedly
+serve to introduce various species of lactic acid bacteria, and will be
+referred to in the portion dealing with soured milks. Keffir is prepared
+by the Caucasians from cows', sheep's, or goats' milk, and the operation
+is carried on in large leathern tubes or bottles. After the addition of
+the grains or seeds to the milk the vessel is placed in a cool chamber,
+and the fermentation is allowed to proceed for one or two days, by the
+end of which time the normal fermentation is at an end. During this
+period the keffir grains have increased enormously in size, assume a
+bright yellow colour, and lose their sour buttery smell.
+
+Previous to the removal of the fermented liquid, a portion of the bottle
+is firmly bound from the rest by a stout cord, and the greater portion
+of the remaining keffir is quickly removed for use, thus avoiding, as
+far as practicable, any outside infection. After the addition of fresh
+warm milk the cord round the end of the bottle is removed, and the old
+and new milk thoroughly mixed for a time in order to ensure uniform
+inoculation of the new milk for the next fermentation. During the winter
+months the leathern vessels are often placed in the sunshine, so that
+the temperature remains at 61 deg. to 65 deg. F.
+
+The necessary agitation of the vessel is said to be supplied in the form
+of kicks by passers-by or by the children during their play.
+
+The beverage prepared in this way is so gaseous in character that it is
+often blown forcibly from the vessel during removal, and possesses,
+according to Podowyssozki,[48] a very acid taste.
+
+During any interruption in the preparation of keffir in the above
+manner, the grains are taken out, and after having been well washed in
+clean water, are spread out on a clean cloth to dry in the sunshine.
+They thereby assume a characteristic cheesy or buttery odour and become
+rather darker in colour. Thorough desiccation is essential in order to
+prevent subsequent mouldiness or disease of the grain.
+
+In European countries the grains are subjected to a preliminary soaking
+in water for five to six hours and then placed in four to five changes
+of milk, each change having a duration of two to three hours. As soon as
+the grains commence to rise to the surface of the milk, they may be used
+for the actual preparation. To this end, a small quantity of the grain
+is added to freshly boiled milk and allowed to stand for eight to twelve
+hours at a temperature of 55 deg.-62 deg. F. with agitation of the flask
+every two hours. By this time the milk, now known as Sakwaska, has become
+abundantly inoculated with the organisms essential to the fermentation,
+and after the removal of the grains, may be poured into well-corked
+flasks for the secondary brew. The flasks should be kept at a lower
+temperature for twenty-four to forty-eight hours, by which time the
+product is ready for consumption.
+
+According to the temperature and length of period to which this
+subsequent fermentation is allowed to proceed, the resultant keffir is
+more or less acid and gaseous. The grains may again be used for starting
+a fresh portion of milk, and a regular supply obtained in this manner.
+Well-fermented forty-eight-hours-old keffir should be an effervescent
+beverage with prickling and acid taste and a consistency and smell
+similar to sour cream. Large, persistent bubbles should form on the
+surface of the liquid and the casein be present as an extremely fine
+flocculent precipitate which remains suspended for a considerable time.
+
+From the third day there ensues a gradual peptonisation of the casein.
+If the temperature at which the secondary fermentation has occurred
+should be higher than 72 deg. F., or if the milk has not been sufficiently
+agitated, then the casein will be present in the form of porous small
+flakes, which on shaking form a fine emulsion.
+
+The chemical changes undergone by the milk during the preparation of
+keffir are confined almost exclusively to the milk sugar. As already
+stated, a slight peptonisation occurs in old samples, but this depends
+very largely upon the method of preparation and purity of the culture.
+Hammersten[49] and Essaulow[50] show, however, that this is not a
+concomitant of normal fermentation. According to Hammersten, normal
+keffir contains--
+
+                            Per cent.
+  Water                       88.26
+  Fat                          3.35
+  Casein                       2.98
+  Lactalbumen                  0.28
+  Peptones                     0.05
+  Milk sugar                   2.78
+  Lactic acid                  0.81
+  Alcohol                      0.70
+  Ash                          0.79
+
+In no case should the acid be higher than 1.0 per cent., and the alcohol
+more than 0.75 per cent.
+
+_Biology of the Keffir Grain._--The first communication on the biology
+of the keffir grain seems to have been made by Kern.[51] He regarded the
+grain as a zoogloea composed of bacilli and yeasts, the latter being
+regarded as the ordinary beer yeast (_Saccharomyces cerevisseae_), while
+to the former he gave the name of _Dispora caucasica_. As the name
+indicates, this bacillus possesses two polar spores, and germination of
+these proceeded in the same manner as with _Bac. subtilis_. As, however,
+pure cultures of the organisms were not made, and the descriptions and
+illustrations made by Kern fail to show any distinctive characteristics,
+it seems probable that accidental confusion with other organisms must
+have occurred.
+
+  [Illustration: A MILK FILLING APPARATUS
+
+  FIG. 10--Where soured milk is handled on the large scale,
+  a special filling apparatus for bottles is desirable, and
+  the soured milk supply should be under cover as shown.
+  This apparatus is made by the Dairy Machinery and
+  Construction Company.]
+
+Krannhals[52] succeeded in isolating ten different keffir bacteria among
+which were several sporulating bacteria. Here too it is impossible to
+attach any importance to the results, as the artificial preparation of
+keffir, by means of these bacteria, was not attempted. Beijerinck[53]
+studied the organisms constituting keffir grains and attached prime
+importance to the occurrence of two organisms, viz., (_a_) a yeast,
+_Saccharomyces kefir_, which was capable of inverting milk sugar by
+means of an enzyme (lactase) and afterwards fermented the products with
+the formation of alcohol and carbon dioxide, and also (_b_) a non-motile
+non-sporulating bacterium, afterwards _Lactobac. caucasicus_. The
+latter, when cultivated on gelatine, gave rise to tough warty colonies
+about 1/40 in. diameter, and was regarded as one of the lactic acid
+bacteria found in milk which has been incubated at 77 deg. to 90 deg. F.
+and afterwards incubated at a higher temperature, 100 deg. to 104 deg. F.
+Scholl[54] isolated three different organisms, of which a yeast inverted
+milk sugar for the lactic acid bacteria, while _Dispora_ peptonised the
+albuminoid matters.
+
+Adametz[55] failed to isolate _Dispora_, and came to the conclusion
+that ordinary lactic bacteria and yeasts played the most important part
+in the fermentation.
+
+Essaulow found in keffir grains six different organisms--yeast cells,
+cocci, short thick bacilli, bent bacilli, long threads, and motile
+bacteria. The two latter would seem to be _Bacillus subtilis_, while the
+others may be regarded as _Bacterium acidi lactici_ (Hueppe), _Bacterium
+aerogenes_, and _Streptococcus lacticus_ (Grotenfeldt). Pure cultures
+were insufficient to produce keffir, while mixed cultures of _Bacterium
+acidi lactici_ and yeasts were effective.
+
+Freudenreich,[56] to whom we owe a record of very carefully executed
+experiments, could not arrive at a satisfactory explanation of the role
+of _Bacillus caucasicus_. This organism is described as being 5-6  mu long
+and 1  mu thick, slightly motile, and possessing bright refractive spots
+at the poles of the bacilli. It is extremely difficult to cultivate, and
+forms flat, small greyish colonies of irregular outline. The bright
+refractive spots above referred to are, however, granules taking the
+usual stains quite readily, and not spores as supposed by Kern.
+
+Freudenreich also found three other organisms--a yeast and two
+streptococci. The yeast, to which he gave the name _Saccharomyces_
+(Torula) _keffir_, forms small oval or roundish cells 2-3  mu wide and 3-5
+ mu long. The optimum temperature would seem to be about 72 deg. F.; the
+maximum 82 deg. F. This organism is unable to ferment milk directly, but is
+able to decompose maltose and glucose with gas production. It does not
+coagulate milk, but imparts to it a characteristic taste and is unable
+to withstand desiccation for more than a few days.
+
+Of the two streptococci isolated, _Streptococcus a_ resembles organisms
+of the group _Streptococcus lacticus_ in appearance, but is able to
+ferment milk, with weak acid and gas production, and is capable of
+inducing coagulation.
+
+  [Illustration: FIG. 11.--Section through a Kephir
+  Grain--highly magnified.]
+
+Contrary to what one would expect in an organism existing in keffir
+grains, this streptococcus is as little able to withstand desiccation as
+the above-mentioned yeast. _Streptococcus b_ forms smaller cells as well
+as smaller colonies than _Streptococcus a_, but produces more lactic
+acid and more gas, and retains its vitality after desiccation. The
+relation of these four organisms is, according to E. von Freudenreich,
+as follows: _Sacch. keffir_ is unable to ferment directly milk or
+lactose, so that its growth must be preceded by that of _Streptococcus
+b_. _Streptococcus a_ does not seem to play this part, but, unlike
+_Streptococcus b_, is able to coagulate milk on its own account. By the
+combined action of the yeast and the two streptococci, then, milk can be
+coagulated, milk sugar inverted, acid and gas produced by the
+streptococci, while gas and alcohol are formed by the activity of the
+yeast. The role of _Bacillus caucasicus_ is unknown, but it would seem
+to play a part in the formation of the keffir grain itself. By means of
+mixed cultures of the above organisms Freudenreich was successful in
+obtaining a fermented product possessing in all respects the
+characteristic properties of normal keffir. On the other hand,
+experiments to induce the formation of keffir grains gave negative
+results, but in this respect the cultural characteristics of
+_Lactobacillus keffir_ would seem to give promise of success in the
+synthesis of the keffir grain. Fig. 11 is a photo-micrograph of an
+extremely thin section through a keffir grain, after a preceding
+treatment with saffranin. The matrix is composed entirely of long thin
+bacilli (_Bacillus caucasicus_), while the peripheral portions, which
+are more deeply stained, consist to a large extent of dense masses of
+yeast cells with occasional streptococci. In a normal grain the latter
+organisms are present on the surface or in the cavities and grooves of
+the grain, and only to a less extent in the matrix. Nikolaiewa[57]
+claimed to have isolated a hitherto unknown bacillus capable of
+coagulating milk by acid production, _Bacterium caucasicum_, not
+identical with, but related to Freudenreich's _Bacillus caucasicus_, and
+also a torula. Although no experiments were carried out, Nikolaiewa
+asserts that this organism forms the matrix of the grains. He was able
+to produce a beverage resembling keffir, just as Freudenreich and
+Essaulow did with entirely different organisms, but his product would
+appear to have been slightly too acid and to have lacked the
+characteristic aroma of the normal product. In the course of an
+extensive series of experiments Kuntze[58] found the following
+organisms:
+
+  (_a_) True lactic acid forming bacteria, _Streptococcus
+  acidi lactici_ (Grotenfeldt).
+
+  (_b_) Bacteria of the group _Bacterium acidi lactici_
+  (Hueppe) and _Bacterium lactis aerogenes_.
+
+  (_c_) Various torula and yeast species.
+
+  (_d_) Two species of butyric acid bacteria, _Bacillus
+  esterificans_ and _Bacillus keffir_ (Kuntze).
+
+His conclusions are: 1. In any case the presence of a yeast capable of
+directly fermenting milk sugar is not essential. 2. The significance of
+the presence of yeast lies in the fact that stimulation of the lactic
+bacteria occurs; further, the yeast exerts a regulating influence upon
+the rapidity of the fermentation proper. The variety is of minor
+importance, provided always that the yeast does not produce an
+unpleasant flavour. By the use of mixed cultures of _Bacillus
+esterificans_, _Bacillus keffir_, and _Streptococcus acidi lactici_, and
+a keffir yeast, Kuntze obtained a product that possessed to the fullest
+degree all the characteristic properties of a normal keffir. In such
+cultures he was successful in obtaining the formation of keffir-like
+grains. Keffir fermentation is, according to Kuntze, the result of the
+action of various organisms. During the initial stage butyric acid
+fermentation takes place, but is prevented from becoming predominant by
+the action of the keffir yeast. Simultaneously a true lactic acid
+fermentation proceeds and eventually gives place to a subsequent
+secondary production of butyric acid. Finally, then, we have a certain
+amount of unison in the results obtained by Freudenreich, Essaulow,
+Nikolaiewa, and Kuntze. These show that, for the production of a
+characteristic keffir, specific organisms are not essential, provided
+always that those used possess, either individually or collectively, the
+essential capacity of acidifying, coagulating, and fermenting the milk.
+For the growth of normal grains the presence of a matrix-forming
+organism, such as _Bacillus keffir_, is indispensable.
+
+  [Illustration: FIG. 12--_Streptococcus lacticus_
+  (Grotenfeldt) growing on lactose-agar, stained by Gram's
+  method. ( X 900 diams.)]
+
+_Diseases of Keffir Grains._--According to the age and the previous
+treatment to which keffir grains have been subjected, the vitality of
+one or more of the organisms constituting the grain may have been
+impaired. The results of Freudenreich have shown that _Saccharomyces
+keffir_ and _Streptococcus a_ are unable to withstand desiccation for
+more than a few days, and this is sufficient to account for the frequent
+failures to obtain normal keffir from the grain. Further, grains succumb
+to a mucilaginous disease; the cavities become filled with a slimy
+fluid, and the grains are covered with mucilaginous matter. They lose
+their elasticity and become brittle or mealy, but large grains appear to
+be more subject to this fault than do the small ones. Such grains
+should be disinfected by immersion for a short time in two per cent.
+salicylic acid solution, followed by drying in the sun, whereby they are
+completely regenerated.
+
+Another disease consists in the predominance of certain butyric acid
+bacteria which impart an unpleasant rancid taste to the keffir
+(Podowyssozki). This is generally attributed to the use of rich milk, or
+too high a temperature during preparation.
+
+_Koumiss._--Another product of the combined action of lactic acid and
+alcohol-producing organisms is called koumiss, kumys, milk-wine, lac
+fermentation, or vinum lactis. In the steppes of Southern Russia and
+Asia, as we have seen,[59] it is prepared chiefly from mares' milk, but
+occasionally from that of camels and jennets. The name is said to be
+derived from that of a tribe mentioned by Xenophon and Pliny, viz., the
+Kumanen, by whom its preparation was practised. After the war with the
+Tartars in 1215 its use was adopted by the latter people, and eventually
+spread to the Turkomanen, Kalmucks, Khirgiz, Mongolians, etc.
+
+Rubruck, in 1253, records the use of a fermented drink--kosmos--prepared
+from mares' milk, and about the same time Marco Polo mentions the
+occurrence of a milk-wine, chumis or chemius, among the Tartars. The
+fact that the Tartars were seldom ill, and were almost invariably free
+from lung troubles, led to an influx of visitors from surrounding
+countries, until finally its use spread to Russia, Austria, and Germany.
+At the present time the best koumiss is that produced in the province of
+Orenburg; but specially equipped koumiss establishments, under the
+control of physicians, exist in Odessa, Samara, Ufa in the Urals, and
+other districts. The curative properties of koumiss have long been
+recognised and its use is indicated in cases of indigestion, chlorosis,
+scurvy, tuberculosis, etc.
+
+Rubinsky states that, among the nomadic tribe, of Khirgiz and Kalmucks,
+a special leathern bottle (Turssuk, Orroth, or Soaba) is used for the
+preparation of koumiss, while wooden tubs (Tschiljak) similar in shape
+to the old-fashioned churn are used by the Bashkirs, and in koumiss
+establishments.
+
+The fermentation is induced by the addition of koumiss to fresh mares'
+milk, in proportions which vary according to the cleanliness observed in
+the actual preparation. Where the process is carefully controlled, one
+part of koumiss to ten parts of milk is often used, but where gross
+infection from outside sources takes place one part of koumiss to three
+parts of milk is taken. The mixture is stirred at frequent intervals,
+and stored at a temperature of 73 deg.-90 deg. F. Weak koumiss is obtained
+after twenty to twenty-four hours in winter and twelve to fourteen hours in
+summer, but is scarcely ever consumed immediately, as it possesses a
+strong purgative action.
+
+It is generally poured into bottles (bottled koumiss); or allowed to
+remain in the tubs (tschiljak koumiss); in the former case the
+fermentation is anaerobic, in the second it is aerobic.
+
+Storage of the koumiss upon ice or in a cellar is necessary since medium
+koumiss is converted to strong koumiss in twelve to sixteen hours at
+ordinary temperatures, while at the lower temperature this occurs only
+in two to four days.[60]
+
+According to Biel,[61] either old koumiss or the dried sediment from old
+koumiss may be used for the initial inoculation. It may also be prepared
+by the repeated inoculation of mares' milk with soured cows' milk until
+a fermenting product is obtained. Koumiss may be prepared by a method
+stated by Allik[62] to be in general use in the Caucasian
+health-resorts. One part of beer-yeast is added to four to ten parts of
+fresh mares' milk (according to the strength of product required), and
+after thorough mixture of the two liquids the whole is allowed to
+ferment at a temperature of 70 deg. to 72 deg. F. for two days. One part of
+this first product is then added to five parts of fresh cold milk, and
+allowed to stand three to four hours at 75 deg. to 77 deg. F. It is then
+poured into bottles, and after the expiration of another three to four
+hours is stored away in a cellar at about 45 deg. F. This koumiss may be
+used at any time from one to five days (generally two to three) after
+bottling according to the strength desired or prescribed in each
+individual case.
+
+The changes undergone during fermentation consist in a vigorous gas and
+acid production accompanied by alcohol formation and coagulation of the
+milk. The coagulum exists in an extremely fine state of division, and
+the liquid froths violently on the bottle being opened. It has a full
+pleasant acid taste, but should not contain more than one per cent. acid
+and two per cent. alcohol. The specific gravity of koumiss is 1.008 to
+1.020 at 60 deg. F. Appended is an analysis of two different samples of
+koumiss:
+
+  ---------------------------------------------------
+                                 Prepared from
+  ---------------------------------------------------
+                          Mares' Milk.     Separated
+                                          Cows' Milk.
+  ---------------------------------------------------
+                           Per Cent.       Per Cent.
+  Water                     91.535          88.933
+  Fat                        1.274           0.854
+  Nitrogenous bodies         1.913           2.025
+  Sugar                      1.253           3.108
+  Ash                        0.293           0.444
+  Carbon dioxide             0.876           1.027
+  Alcohol                    1.850           2.647
+  Lactic acid                1.006           0.796
+  Glycerine                   ....           0.166
+  ---------------------------------------------------
+
+Fleischmann[63] gives a formula for preparing an artificial koumiss from
+separated cows' milk, water, cane sugar, and milk sugar, with the
+addition of distillery yeast. Needless to say, this product must possess
+some of the characteristic by-flavour of the yeast employed, and is less
+suitable than koumiss prepared by the aid of a lactic yeast. Schipin
+investigated the fermentation of koumiss and found three distinct
+organisms.
+
+Rubinsky in a recent article threw much light on the phenomena of
+koumiss fermentation. According to him, koumiss contains almost
+invariably four different organisms, viz., koumiss yeast, koumiss
+bacterium (_Lactobacillus_), _Streptococcus lactis_ (Lister), _Bacterium
+aerogenes_, and occasionally _Bact. caucasicum_ (Nikolajewa). For the
+preparation of normal koumiss only the two former organisms are
+required; they exceed in number any of the other organisms whose
+presence in the dairy is unavoidable. The presence of the two latter
+organisms is favourable to the production of good koumiss, as, by
+inducing a preliminary lactic fermentation, they tend to inhibit the
+growth of undesirable extraneous bacteria, etc. In medium and strong
+koumiss they die out on account of the amount of lactic acid formed
+(1%).
+
+Koumiss yeast possesses strongly differentiated protoplasm, but lacks
+any cultural characteristics. Abundant growth occurs in milk, and lactic
+acid (0.3%), alcohol, carbon dioxide, albumens and peptones, volatile
+acids, and aromatic substances are formed.
+
+Koumiss bacterium is related to the _Lactobacillus_ of various other
+fermented milks, and is similar to _Bac. acidophilus_, and possesses
+like these a distinct polymorphism (branched cells, long and short
+bacilli, etc.). It is non-sporogenous, has an optimum temperature of 90
+deg. to 97 deg. F., and possesses cultural characteristics similar to
+those of the rest of the _Lactobacilli_.
+
+The by-products of koumiss yeast appear to favour the growth of the
+koumiss bacterium, as this organism, like the other _Lactobacilli_, is
+favourably influenced by the presence of small quantities of peptone,
+alcohol, and acid.
+
+The organisms found by Schipin consisted of a species of _Saccharomyces_
+and two bacilli, _Bacillus acidi lactici_ and a non-sporulating
+bacillus. The latter organisms coagulate milk at 98 deg. F., but not at
+room temperature, and although a minute description of cultural
+characteristics is not given it would seem to be related to _Bacillus_
+or _Lactobacillus caucasicus_.
+
+_Leben Raib_ or _Leben_ (_Laban._)--This is a beverage prepared largely
+by the Egyptians, and differs from keffir, as does matzoon, in
+possessing a characteristic aroma and taste. It differs also from the
+former by having only a very weak alcoholic fermentation, and by the
+coagulum being coarse and lumpy instead of being extremely fine. It is
+made from buffaloes', goats', or cows' milk by the addition of roba (or
+old leben) to the previously boiled and cooled fresh milk. The use of
+leben is many centuries old, and it is used in Egypt as in Arabia for
+medicinal purposes, although that of the Syrians and Arabians is said to
+differ from that of the Egyptians and Algerians. The fermentative
+changes occurring in the formation of the Egyptian leben have been
+investigated by Rist and Khoury,[64] and also by Guerbet,[65] who found
+that five organisms were normally present. These comprised a
+chain-forming bacillus (_Streptobacillus_), a second smaller bacillus
+(_Bacillus lebenis_), a diplococcus, a saccharomyces, and a mycoderma.
+Of these five organisms, it would appear that four live in metabiosis,
+the streptobacilli and bacilli hydrolyse the milk sugar, the components
+of which are split up by the yeast to alcohol and carbon-dioxide. The
+alcohol thus formed, together with the glucose formed by hydrolysis, are
+eventually converted to acid or combusted by the mycoderma species. The
+leben thereby assumes the sharp, unpleasant flavour met with in old
+samples. The diplococcus merely produces acidification and coagulation
+of the milk. Rist and Khoury were able, by the use of these organisms,
+to produce normal leben, especially when the true yeast was allowed to
+grow in the milk for some time before inoculation with the other
+organisms was made.
+
+Some of the half-civilised tribes of Siberia, the Tartars and the
+Burgaten, prepare a strong alcoholic beverage, araka or ojran, from
+fermented milk. This is really a product of distillation, and contains
+seven to eight per cent. of alcohol and volatile fatty acids.
+
+  [Illustration: FIG. 13--Photo-micrograph of preparation
+  from Armenian soured milk (Matzoon). This is related to
+  Yoghourt, and contains, as will be seen from the above
+  photo, yeasts, streptococci, diplococci, and a bacillus
+  with the morphology of _Bacillus bulgaricus._ This, and
+  similar foods, owe their peculiar properties primarily to
+  the presence of _Bacillus bulgaricus_ (type A, White and
+  Avery), and only in a lesser degree to the yeasts and
+  lactic streptococci.]
+
+_Matzoon._--This is a drink used largely in Western Asia, and is similar
+in character to keffir, but has a peculiar taste which distinguishes it
+from all other fermented milks. According to Weigmann,[66] it is
+prepared from buffaloes', goats', or cows' milk, and is used partly as a
+means of souring milk for butter-making and also as a lactic food, eaten
+with spoons. In the same way buttermilk produced from milk which has
+been previously ripened by matzoon is used as a beverage. Finally, the
+coagulum (_than_) of such buttermilk is strained off, and, after being
+pressed, is mixed with meal and dried by exposure to the sun's rays. The
+preparation of matzoon is in many respects very similar to that of
+keffir and koumiss, but differs by inducing a comparatively weak alcohol
+fermentation. In common, too, with yoghourt, the prevailing temperature
+is much higher than is required for keffir and koumiss.
+
+In regard to the biology of matzoon, the occurrence of various organisms
+has been recorded. Emmerling[67] isolated, in addition to a yellow
+pigment-forming organism, _Bacillus subtilis_, _Bacillus lactis acidi_,
+and several fungi, a small micrococcus capable of hydrolysing milk- and
+cane-sugar. The organism produces and without gas formation, or
+peptonisation of the medium. Of the nine yeasts isolated from matzoon by
+Lindner[68] and Kalantharianz,[69] three were able to ferment milk sugar
+without previous hydrolysis, while two others, by the simultaneous
+production of lactic acid and fruit esters, gave to the matzoon its
+characteristic taste and aroma.
+
+_Yoghourt and Soured Milk._--Yoghourt is another fermented milk, and is
+related to the matzoon of Armenia, the gioddu of Sardinia, and the leben
+of Egypt. After a preceding boiling and reduction of the volume of the
+milk, inoculation of the mass is made by the addition of a small
+quantity of old culture, and it is then allowed to sour at a
+comparatively high temperature. A moderately compact, jelly-like
+coagulum is thus formed, while keffir and koumiss possess a liquid
+consistency. The fermentation necessary for the two latter products only
+proceeds, too, at a much lower temperature, at which yeasts play an
+important part. According to Guerbet, yoghourt incubated for ten hours
+at 113 deg. F. contained 0.34 per cent. lactic acid and 0.012 per cent.
+alcohol. Luerssen and Kuehn[70] came to the conclusion that yoghourt
+contained chiefly a mixture of _Bacillus bulgaricus_, diplostreptococci,
+and a "granule" bacillus, so called on account of its granulated
+appearance after treatment with methylene blue. According to these
+authors, the first two organisms were found in each of eight samples of
+maya (young yoghourt) and of yoghourt itself, but the occurrence of the
+"granule" bacillus in plate cultures was by no means regular. In
+addition, yeasts were found in almost every sample examined, but were
+regarded more as accidental infections rather than as essential to the
+formation of a typical product. The combined action of the three
+organisms already mentioned gave rise to a product closely resembling
+normal yoghourt. Piorkowski[71] subjected Bulgarian maya to examination
+and associated himself with Metchnikoff[72] in finding three species, a
+streptococcus, a diplococcus, and a specific organism to which he gave
+the name _Yoghourt bacillus_. Similar results were also obtained by
+Grigoroff.[73] Piorkowski's _Yoghourt bacillus_ is similar in form to
+_Bacillus subtilis_, but does not sporulate, nor does it liquefy
+gelatine. Young individuals are stained by Gram's method; older
+individuals are, however, Gram negative. The optimum temperature is 112
+deg. F. Kuntze attempted to isolate the organisms mentioned by Luerssen and
+Kuehn, and by plate culture procured growth of a spore-forming bacillus
+similar to Weigmann's _Bacillus matzoon_. To this organism is attributed
+the power to impart a specific taste to the matzoon, but as growth is
+comparatively slow, it can only be of significance in determining the
+quality of the curd and cheese prepared from this product. Cultures were
+also obtained which resembled in general character those of the organism
+described by Luerssen and Kuehn as _Bacillus bulgaricus_ and named by
+Kuntze _Bacterium W_. Granule formation was transient in this culture,
+and the organisms eventually became inactive. Further analysis of maya
+gave cultures of the "granule" bacillus, but these passed over from the
+type forming irregular colonies (see Figs. 14, 15, 16) to that producing
+smooth colonies. Further, although the granule formation persists
+largely in milk, the organisms soon revert to the non-granular type if
+cultivated on agar. By the use of the Gram-Weigert stain organisms from
+a several-days-old culture on beer-wort-agar gave an interesting
+reaction. The bacillar threads are in places Gram-negative, in others
+Gram-positive, and bear small club-like swellings (see Fig. 14). Results
+similar to these were also obtained with cultures of _Bacillus matzoon_
+(Weigmann and Gruebner) and also with _Bacillus acidophilus_.
+
+Neisser's method of staining failed to give such good effects by the
+examination of fresh maya, as did an alcoholic aqueous solution of
+methylene blue in showing up the granules of the organisms. Again,
+Grixoni[74] found, but did not isolate, a similar granule-forming
+organism (_Bacterium sardous_) in Sardinian gioddu. As already
+mentioned in the description of leben, Rist and Khoury found a long
+bacillar lactic ferment (_Streptobacillus lebenis_) which also exhibited
+the irregular greyish white hairy colonies and high optimum temperature
+characteristic of this group. On account of the similarity in form,
+staining reactions, temperature requirements, and cultural growth of the
+organisms described by Emmerling, Dueggeli, Weigmann, Grixoni, and Rist
+and Khoury, Kuntze is inclined to regard them as belonging to one single
+group of lactic ferments. According to him the granule formation is
+rather variable, and may be induced or suppressed by cultural methods.
+Not only do organisms of this group produce far more acid than the
+normal lactic bacteria; they are also more resistant to acid, and are
+able to develop in milk to which 0.5 per cent. hydrochloric acid has
+been added. A comparatively high percentage of alcohol seems to
+encourage growth, and this was obtained in milk containing 4 per cent.
+alcohol. This would no doubt tend to explain the phenomenon observed by
+Kuntze that milk is not so rapidly fermented by organisms of this group
+as when cultures of diplococci and yeasts are added. Since organisms of
+this group would seem to be widely distributed, the question of their
+natural habitat arises. Luerssen and Kuehn were unsuccessful in their
+search for such organisms in Koenigsberg milk, but Leichmann records the
+occurrence of a long bacillus (_Bacillus lactis acidi_) in milk that had
+spontaneously soured at 112 deg. to 120 deg. F. This organism, too, showed
+characteristic growth on agar media, and produces laevo-rotatory lactic
+acid. The examination of calves' stomachs showed, according to Kuntze,
+only occasional long bacilli, but inoculation of sterile milk and
+incubation at 100 deg. F. with repeated over-inoculation gave a culture
+showing the characteristic granule reaction (see Figs. 18 and 20).
+Although plate cultures made direct from calves' stomachs do not exhibit
+the regular contours generally shown by the granule bacillus, yet this
+growth may be induced by preceding cultivation in lactose bouillon to
+which 0.5 per cent. acetic acid has been added. A similar organism,
+_Bacillus acidophilus_, was isolated from calves' manure by means of
+this acetic bouillon, as was also a diplostreptococcus which resembled
+very closely the typical lactic acid streptococcus. This resemblance was
+made all the more striking by the fact that they were capable of
+coagulating milk at a temperature of 99 deg. to 104 deg. F. Since these
+organisms are present in large numbers in manure and also in the
+digestive tract of ruminants, it would seem probable that their
+occurrence is not without significance for the operations of cheese
+manufacture. According to Jensen, the practice of applying farmyard
+manure to Swiss meadows has been regarded as absolutely essential to the
+production of cheese of the best quality; while, on the other hand, the
+application of artificial manures would seem to have been responsible
+for an increase in abnormal cheese. Kuntze found further that by the
+combined inoculation of sterile milk with the diplostreptococcus and the
+"granule" bacillus from calves' stomachs, together with a yoghourt
+yeast, he was able to obtain a product possessing a taste and aroma
+little different from normal yoghourt. During their investigations upon
+the ripening of Swiss hard cheese, Freudenreich and Jensen[75] isolated
+five varieties of lactic acid bacilli, and were able to show that one of
+these, especially _Bacillus casei [Greek: e]_, was of the greatest
+importance for the production of good cheese. This organism has been
+found by Thoeni to be present in rennet tablets, while a related
+variety, _Bacillus casei [Greek: d]_, was found in fresh calves'
+stomachs. Unfortunately, staining tests with these organisms were not
+carried out, so that no data are available in regard to the presence of
+granules. The photo-micrographs of these organisms show the small clubs
+and true-branched forms. The presence of these diplococci and bacillar
+lactic ferments in the intestinal tract of ruminants and horses might
+possess some importance for the preparation of yoghourt in bags or tubes
+made from the stomachs of these animals. Finally, Moro[76] has isolated
+an acidophilic organism from the dejecta of infants which resembles
+closely, both in manner of growth, resistance to acids, true branching,
+and temperature optimum, the granule bacillus and related forms.
+
+[This group of sixteen illustrations (Figs. 14 to 29), showing various
+aspects of the Yoghourt bacillus and others of a cognate nature, is
+taken from the _Centralblatt fuer Bakteriologie_ of Jena.--L. M. D.]
+
+  [Illustration: FIG. 14.--Granule Bacillus from Yoghourt.
+  Shredded preparation of a fresh skim-milk culture at 37 deg.
+  C. for six hours. Stain: aqueous methylene blue. (Enlarged
+  1:500.) In Figs. 15 and 17 will be noticed the chain
+  arrangement of the bacillus, which, in spite of the
+  supposed data of Luerssen and Kuhn, will be generally
+  noticed in the granule bacillus.]
+
+  [Illustration: FIG. 15.--Granule Bacillus from Yoghourt,
+  cultivated after the usual Agar method, for twenty-four
+  hours at 37 deg. C. Stain: aqueous methylene blue. (Enlarged
+  1:500.)]
+
+  [Illustration: FIG. 16.--Granule Bacillus from Yoghourt.
+  Agar Milk Sugar Culture cultivated for forty-eight hours
+  at 37 deg. C. Below is the true branching, above, the
+  distorted involution form. This production of involution
+  forms occurs chiefly in old cultures, and is an indication
+  of degeneration. Stain: aqueous methylene blue. (Enlarged
+  1:700.)]
+
+  [Illustration: FIG. 17.--_Bacteria W._ from Milk,
+  cultivated twenty-four hours at 37 deg. C. Methylene blue.
+  (Enlarged 1:500.) The similarity in the pictures ought to
+  serve as a proof of the near relation of the granule form
+  and non-granule varieties.]
+
+  [Illustration: FIG. 18.--Agar Milk Sugar Culture. From the
+  original Bulgarian Yoghourt. In the centre, and beneath,
+  the characteristic hairy irregular colonies of the granule
+  bacillus (_Bacillus bulgaricus_ group), to the left, the
+  smooth contoured yeast colonies. The colonies of the
+  former organism always remain microscopic in size.
+  (Incubated several days at 20 deg. to 25 deg. C. Magnified X 10.)]
+
+  [Illustration: FIG. 19.--Agar Milk Sugar Culture. Surface
+  colony of granule bacillus from calf's stomach. The great
+  resemblance this colony bears to those formed by the
+  granule bacillus from Yoghourt will be apparent. This
+  fact, as well as close agreement in other cultured
+  features, induced Kuntze to place these organisms in one
+  group. (Incubated two days at 37 deg. C. Magnified X 100.)]
+
+  [Illustration: FIG. 20.--Agar Milk Sugar Culture.
+  Deep-lying colony of granule bacillus from calf's stomach.
+  The form of the colony is often determined by the relative
+  presence or absence of air. (Two days at 37 deg. C. Enlarged
+  about 1:50.)]
+
+  [Illustration: FIG. 21.--Agar Milk Sugar. Colony of
+  _Bacterium W._ from Yoghourt (non-granular variety of the
+  granule bacteria, as far as possible identical with
+  Luersen and Kuehn's _Bacillus bulgaricus_), of a cubical
+  branching-out form.
+
+  According to Kuntze, the granule formation of this and
+  related organisms is variable, while White and Avery
+  regard it as a constant characteristic. (Incubated two
+  days at 37 deg. C. Magnified x 50.)]
+
+  [Illustration: FIG. 22.--Two colonies of _Bacillus
+  acidophilus_ from calf's manure. Agar Milk Sugar Culture.
+  With this organism, also, we have conformation to one type
+  of colony, while, in other respects, temperature
+  requirements and production, etc., we have close agreement
+  with the granule bacillus (_Bacillus bulgaricus_). (Two
+  days at 37 deg. C. Enlarged about 1:50.)]
+
+  [Illustration: FIG. 23.--Beer-wort Gelatine.
+  Fourteen-days-old colony of Yoghourt yeast. (Enlarged
+  about 1:50.)]
+
+  [Illustration: FIG. 24.--Shredded preparation of the
+  Bulgarian original Yoghourt. Stain: aqueous methylene
+  blue. Granule bacillus, diplostreptococci, and yeast. (See
+  also other photo-micrographs of Yoghourt. Enlarged
+  1:70.)]
+
+  [Illustration: FIG. 25.--Granule Bacillus from Yoghourt.
+  Cultivated in skim milk in twenty-four hours at 37 deg. C.
+  Stain: aqueous methylene blue. (Enlarged 1:50.)
+
+  By means of this staining treatment the presence of
+  granules (not spores) can be easily detected. Treatment
+  with fuchsine fails to bring out these formations.]
+
+  [Illustration: FIG. 26.--_Bacteria W._, Agar Milk Sugar
+  Culture. Cultivated twenty-four hours (knobs, clubs).
+  Stain: Gram's method coloured with aqueous fuchsine
+  afterwards. (Enlarged 1:600.)]
+
+  [Illustration: FIG. 27.--_Bacteria acidophilus_ from
+  calves' manure, isolated by means of bouillon as acid as
+  vinegar. Shredded out of the usual Agar culture.
+  Twenty-four hours at 37 deg. C. Stain: aqueous methylene blue.
+  (Enlarged 1:700.)]
+
+  [Illustration: FIG. 28.--Mucus from calf's stomach
+  inoculated into milk after eight transferrings. Shredded
+  preparation cultivated in milk for twenty-four hours at
+  37 deg. C. Diplostreptococci and granule bacillus. Stain:
+  aqueous methylene blue. (Enlarged 1:500.)]
+
+  [Illustration: FIG. 29.--Diplostreptococcus from Yoghourt.
+  Pure culture in skim milk. A comparison of the
+  illustrations will show how close a resemblance exists
+  between bacteria found in the mucous membrane of calf's
+  stomach and those occurring in Yoghourt. In fact, by the
+  combined action of granule bacilli, and of
+  diplostreptococci from calf's stomach, together with a
+  Yoghourt yeast, it is possible to prepare normal
+  Yoghourt.]
+
+In a review of the literature of the subject of soured milks, Makrinoff
+suggests the adoption of the two names, _Streptobac. lebenis viscosus_
+and _Streptobac. lebenis non-viscosus_, for the organisms of the
+so-called Bulgaricus group, and known at present as
+_Bacillus-bulgaricus_, _Streptobac. lebenis_, _Bacillus of Massol_,
+_Granule bacillus_, _Bact. Mazun_, _Bac. lactis acidi_, etc.[77]
+
+White and Avery[78] have made a comparative study of a large number of
+varieties and species of lactic acid bacteria of the above type obtained
+from various fermented milks and milk tabloids. Their descriptions are
+so detailed and their conclusions are so important that we give them at
+length. According to this work, the whole of the thermophilic lactic
+acid bacilli of the so-called Bulgaricus type may be divided into two
+sub-types, A and B.
+
+
+_The Cultural Characteristics of the Bacillus Bulgaricus Group_
+
+The cultural characteristics of all the strains of _Bacillus bulgaricus_
+(granule bacillus) are as follows:
+
+_In Whey Agar._--All strains exhibit wide variation in size, 2  mu to 50  mu
+long and about 1  mu broad.
+
+Almost all individuals are intensely Gram-positive, and show regularity
+of outline. All strains show involution form, exhibiting vacuoles, and
+often show empty cell membranes. The latter are Gram-negative, and vary
+greatly in both dimensions as well as in form. All strains show tendency
+to chain formation, some being arranged in chains of six to twenty-five
+segments, which may contain both Gram-positive and Gram-negative
+individuals. Type B exhibits Gram-negative spherical bodies varying from
+0.25  mu to 1  mu in size, adhering to the sides of some of the
+Gram-negative individuals.
+
+_In Whey._--In this medium there is a marked tendency toward
+degeneration and involution. In the early stages of incubation, at 100 deg.
+to 112 deg. F., the bacilli are uniform in size and intensely Gram-positive;
+in succeeding stages the irregular, vacuolated, inflated, and ruptured
+forms predominate. Between the eighteenth and twenty-fourth hours of
+incubation at 112 deg. F. the strains of type A develop oval to
+kidney-shaped nodules attached to a stem extending from the cell
+substance. As the incubation is prolonged these nodules increase in
+size, often measuring 1  mu to 2  mu in length; this nodule formation occurs
+at the expense of the cell protoplasm, and appears to be a marked
+characteristic of growth in whey. Cultures of type B do not form nodules
+or clubs, but small spherical bodies more or less securely attached to
+the cell wall are seen. Again, type A assumes the form of small bacilli
+in chains, while type B strains develop to a greater length and exist
+almost exclusively as single isolated forms. True branching has been
+observed in strains of type B.
+
+_In Milk._--In milk there is a tendency to thread-formation consisting
+of four to ten segments in the case of type A, while type B shows longer
+and more curved forms. With increasing age of the culture there also
+appears to be increase in the length of the organisms. All strains are
+non-motile, non-sporogenous, and non-capsule-forming.
+
+_Staining Reactions._--All strains are readily stained by the usual
+aniline dyes.
+
+_A. Gram's Method._--Young individuals give an intense reaction with
+this stain; old bacilli are easily decolourised, and degenerate forms
+are always Gram-negative, while single individuals have been observed
+which showed gradation from one pole of the cell to the other.
+
+_B. Loeffler's Methylene Blue._--According to the behaviour of the
+organisms studied, a separation into two types appears possible, type A
+being uniformly impregnated, while type B shows distinct
+differentiation. The cell body is seen to contain a varying number of
+round to oval bodies or granules. This is the appearance already
+mentioned by Dueggeli, Luerssen and Kuehn, and Kuntze, and from which the
+granule bacillus derives its name. In opposition to the observations of
+Kuntze, the occurrence of granules was not found to be variable; it was,
+indeed, so constant as to constitute a distinguishing characteristic
+between the two types. The organisms of this group are difficult to
+cultivate, and freshly isolated growth is obtainable only on media
+containing whey, malt, or in milk. They grow equally well under aerobic
+or anaerobic conditions. The optimum temperature for growth is 113 deg. to
+115 deg. F.; growth is fair at 85 deg. F., slight at 75 deg. F., and does
+not take place at 68 deg. F.
+
+Colonies on whey agar are round to irregular, greyish white, curled and
+filamentous, often streaming, and in a few cases smooth and even in
+structure. Gelatine is not liquefied. There is no surface growth on
+gelatine stab-cultures. Along the stab the growth is filiform, beaded,
+with subsequent horizontally projecting ramifications. Milk is
+coagulated in eight to eighteen hours at 112 deg. F., and is the most
+favourable medium for growth.
+
+[I am indebted for this group of illustrations (seventeen in number) to
+the editor of _Bacteriotherapy,_ New York, U.S.A.--L.M.D.]
+
+  [Illustration: FIG. 30--Photo micrograph of preparation
+  made from Yoghourt, showing yeast cells, large lactic
+  diplococci, small slender bacilli and many large bacilli
+  possessing the morphology of _Bacillus bulgaricus_. Yeast
+  cells are almost invariably found in native Yoghourt, but
+  do not appear to be essential to the production of a
+  tropical beverage. Indeed, they would seem to be
+  responsible for the unpleasant astringent taste often met
+  with in old samples of this product.]
+
+  [Illustration: FIG. 31--Photo micrograph of smear from
+  Greek Curdled Milk called "Giaourti," and showing yeast
+  cells, long bacilli and a mould (_Oidium lactis_),
+  possessing very large elongate cells. The presence of the
+  latter is very undesirable, as it rapidly combusts the
+  lactic acid, digests the casein, and imparts a strong
+  unpleasant cheesy flavour to the beverage.]
+
+Type A produces 2.7 per cent. to 3.7 per cent. inactive lactic acid in
+milk, while type B produces only 1.2 per cent. to 1.6 per cent.
+laevo-rotatory lactic acid in milk. There is a small quantity of acetic,
+formic, and succinic acids formed. The conclusions of White and Avery
+are:
+
+I. A review of the morphological culture and biochemical features of the
+lactic acid producing bacilli from yoghourt, matzoon, and leben, appears
+to justify their classification as a single group.
+
+II. This group would seem to be identical with _Bacterium caucasicum_
+(Kern).
+
+III. The significant variations exhibited by these bacilli in regard to
+the presence or absence of granules demonstrable by differential stains,
+the degree of lactic acid production, and the nature of the acid
+produced, suggest a division into two different types--the true type A,
+and the paratype B.
+
+Quite recently Hastings and Hammer[79] recorded the isolation from milk
+of an organism producing more acid than either _Bacterium coli commune_
+or _Bacillus lactis acidi_. It is characterised by possessing a high
+optimum temperature, and by the limited conditions under which it grows
+on nutrient media. On this account these investigators suppose it to be
+related to those described in the paragraphs on fermented milks, leben,
+matzoon, etc., and which are regarded by Kuntze as being identical.
+
+Similarly Boutroux[80] found 1.5 per cent. acidity produced in a
+solution containing albuminous matter and glucose; while Richet[81]
+states that with the addition of gastric juice to milk as much as four
+per cent. acidity may be formed. After storing samples of milk for eight
+days at 100 deg. F., Koning[82] found 2.35 per cent. and 2.5 acid; while
+similar samples stored at 60 deg. to 62 deg. F. for the same period only
+developed 0.9 per cent. Heinemann[83] records the production of 3.0 per
+cent. acid in milk incubated at 100 deg. F.; and Jensen states that
+_Bacillus casei [Greek: e]_ is capable of developing 2.7 per cent.
+lactic acid.
+
+Dr. H. B. Hutchinson, bacteriologist at Rothamsted Experimental Station,
+has also been successful in isolating a bacillus from English market
+milk resembling in every particular those classified by White and Avery
+as type A.
+
+  [Illustration: FIG. 32 is a photo-micrograph of soured
+  milk inoculated with a tablet containing viable and pure
+  cultures of _Bacillus bulgaricus_, and incubated for
+  seventy-two hours. These tablets constitute a valuable
+  means of preparing soured milk for therapeutic purposes.]
+
+  [Illustration: FIG. 33 is a photo-micrograph of milk
+  inoculated with a ferment tablet in which _Bacillus
+  bulgaricus_ is no longer viable, and the only growth
+  obtained is that of an organism allied to the _Bacillus
+  subtilis_ (Hay bacillus) group. Such milk would be
+  absolutely without value.]
+
+It will thus be seen that organisms related to those of Oriental and
+Occidental milk beverages are present in conditions where it is
+impossible for them to attain to any active growth. The same class of
+organism has also been found in many cases in butter and cheese
+throughout the United States.
+
+Of recent years the consumption of milk fermented by these organisms has
+been introduced more or less successfully into all European countries.
+This custom is due, as we have seen,[84] to a very great extent to the
+announcement of Metchnikoff[85] that the action of such organisms in the
+alimentary tract conduce to a prolongation of life. Moro found that the
+dejecta of children contain large numbers of _Bac. lacidophilus_ and
+_Bac. bifidus_, but, as age advances, the bacterial flora of the
+intestines tends to change. The number of acid-producing organisms
+gradually becomes less, and other bacteria capable of producing
+far-reaching decomposition of albuminoid matter tend to increase.
+
+Working on the assumption that senility is partially due to the
+absorption of by-products formed from albuminoid food by the
+decomposing or putrefactive bacteria mentioned, Metchnikoff instituted a
+search for organisms capable of suppressing the growth of the
+putrefactive bacteria.
+
+It has long been known that milk allowed to become sour will keep for a
+considerably longer period in hot weather than if lactic bacteria had
+not grown. This preservative action of lactic acid also comes into play
+in the manufacture of sauerkraut and in the preservation of meat by
+immersion in sour milk.
+
+  [Illustration: FIG. 34.--Photo-micrograph of smear of
+  culture of _Bacillus bulgaricus_, recommended by
+  Metchnikoff for use in cases of intestinal
+  auto-intoxication. Unlike the ferments of normally soured
+  milk, which are sometimes indifferent, or even injurious,
+  in their action, this bacillus is capable of growth at
+  blood heat, and, by producing much larger quantities of
+  lactic acid than such organisms as _Streptococcus
+  lacticus_, _Bacillus coli commune_, or _Bacteria lacticus
+  aerogenes_, inhibits the multiplication of bacteria
+  responsible for the putrefaction of albuminoid food in the
+  intestines.]
+
+Bienstock has shown that the growth of _Bac. putrificus_ is inhibited by
+the action of _Bact. coli commune_, which is capable of setting up a
+slight lactic acid fermentation. _Bact. coli commune_, however, gives
+rise to substances of an injurious character, and, although present very
+abundantly in the intestinal tract, it may by reduced almost entirely by
+the active growth of lactic acid bacteria. This fact is of great value
+to the cheese-maker, since by the addition of a lactic acid culture
+(starter) to milk before renneting, gas-producing bacteria such as
+_Bact. coli_ may be checked in growth. Since the ordinary lactic acid
+bacteria such as _Streptococcus lacticus_, _Bac. lactis acidi_, and
+others, are incapable of growth at blood temperature, it appeared
+necessary to procure cultures of lactic bacteria able to grow at
+temperatures of 100 deg. F. to 112 deg. F. Such an organism was found in
+Bulgarian soured milk (yoghourt), and was considered pre-eminently
+adapted to this purpose. As has been shown in the preceding paragraphs,
+this organism is merely one of a large group of bacteria found
+distributed in the intestinal canal of many domestic animals, in manure,
+and in ordinary market milk. It is then not surprising that the
+introduction into the intestinal tract of bacteria of the type
+_Bulgaricus_ in the form of tabloids has not met with any decided
+success. Although it was considered to be merely necessary to introduce
+the desired type of organism into the body, and the amount of lactic
+acid taken into the system by the administration of soured milks was
+looked upon as of secondary importance, yet, it would seem, in the light
+of recent investigations, that benefits derived from a soured milk
+regimen are attributable in part to a chemical as well as a purely
+bacterial action. This receives support from the fact that soured milk
+beverages prepared by the use of ordinary lactic bacteria, distinct from
+those of the _Bulgaricus_ type, often exert a beneficial influence upon
+human beings even although the organisms responsible for the
+fermentation are incapable of growth at blood temperature.
+
+It may be mentioned in conclusion that cultures prepared by the use of
+organisms of the type _Streptococcus lacticus_ combined with _Bac.
+bulgaricus_ possess a more agreeable flavour and aroma than those
+prepared from a pure culture of _Bulgaricus_ alone.
+
+  [Illustration: FIG. 35--_Bacillus bulgaricus_, showing the
+  cultures in English cow's milk. (Magnified 450 diams.)]
+
+  [Illustration: FIG. 36--Photo-micrograph of pure culture
+  of _Bacillus bulgaricus_. The administration of cultures
+  of this organism is indicated in all cases of intestinal
+  ailments, caused by the excessive growth of proteolytic
+  bacteria, and consequent putrefaction of foods in the
+  alimentary tract. By the formation of large quantities of
+  lactic acid, a state of asepsis is ensured, which is
+  particularly valuable in cases of operations on the
+  abdomen and intestines.]
+
+  [Illustration: FIG. 37.--Photo-micrograph of smear of
+  combined culture of _Bacillus bulgaricus_ and _Bacteria
+  paralacticus_. This double culture possesses an advantage
+  over single cultures in that, while the characteristic
+  disinfecting action of the former is retained, any
+  secondary action of the growth of this organism upon the
+  milk-fat is checked by the growth of _Bacillus
+  paralacticus_, thus ensuring the production of a more
+  palatable product.]
+
+
+
+
+CHAPTER VI
+
+THE PREPARATION OF SOURED MILK IN THE HOUSE
+
+
+There is no great difficulty in making soured milk at home: the
+necessary operations are quite simple, but at the same time they must be
+conducted with precision and care, otherwise the results may be
+unsatisfactory and disagreeable; there may even sometimes be danger in
+badly prepared sour milk. It is always an advantage in such matters to
+understand the reason of things, and a few notes on the surrounding
+conditions, and what has to be accomplished, may be of assistance to the
+would-be experimenter.
+
+The majority of intelligent people are now acquainted with the fact that
+the germs of bacteria are to be found everywhere on the surface of the
+earth, in air, and in water, and that they are the sole cause of the
+decay of all manner of perishable articles.
+
+The distribution is unequal--bacteria are much more plentiful where
+there is decaying matter--in dirty houses, sewage, or other contaminated
+water, etc. Milk is a splendid food for bacteria, and numerous varieties
+multiply in it exceedingly, and many of these are injurious, producing
+putrefactive changes which render the milk unwholesome, even poisonous
+in some cases. Others are beneficial, and are absolutely necessary for
+the souring of milk for making butter or cheese and for the ripening of
+the latter. The soured milk which is the subject of this book is the
+work of certain lactic-acid-producing bacteria, and the problem we have
+before us is to encourage the growth of the latter to the uttermost and
+to exclude the others.
+
+As bacterial germs are present in the air and readily sow themselves
+into any medium with which they come in contact, the first consideration
+is to get good fresh milk which has been as little exposed to the air as
+possible. The second is to conduct the experiment where the germs are
+fewest, and in cleanly surroundings, far removed from decaying matter
+and free from taints and smells.
+
+  [Illustration: FIG. 38.--Photo-micrograph of smear of
+  one-month culture of _Bacillus bulgaricus_. In spite of
+  its age, the culture is perfectly free from any foreign
+  organisms, which would otherwise lower its value for the
+  preparation of soured milk, and might, indeed, make it
+  directly injurious.]
+
+  [Illustration: FIG. 39.--Photo-micrograph of culture of
+  _Bacillus bulgaricus_ in malt. In cases of acute
+  enteritis, where milk cannot be supported, the lactic
+  bacilli may be cultivated in malt, and administered to the
+  patient in this form, with occasional doses of syrup of
+  malt, in order to induce a vigorous growth of the lactic
+  ferments in the body.]
+
+  [Illustration: FIG. 40.--Photo-micrograph of smear from
+  milk that had been allowed to sour spontaneously. Ordinary
+  market milk is always subject to infection from the air,
+  milking vessels, manure, etc., and from these sources a
+  mixed bacterial flora arises, with the result that the
+  milk exhibits curdling, acidity, gaseous fermentation, or
+  mould growth, after being stored for a short time. This is
+  due to the action of sush bacilli, diplococci, yeasts, and
+  moulds as are shown in this illustration.]
+
+However fresh the milk may be, it will contain useless or injurious
+bacteria, and we must get rid of these before attempting to introduce
+those whose growth we wish to encourage. This is effected by heat. All
+the living bacteria and most of the germs are killed at temperatures
+somewhat under the boiling point. Having sterilised the milk in this
+way, it is necessary, as far as possible, to prevent the entrance of
+fresh germs from the atmosphere, and we therefore let the milk cool down
+in covered dishes. When the temperature descends to about 100 deg. F. the
+culture of the special bacteria is introduced, the covers are replaced,
+and the milk vessels maintained at or near this temperature for twelve
+hours, when the soured milk is ready for use. It is not necessary to use
+fresh culture every time--a little of the soured milk will take its
+place, and this may be repeated as many as fourteen times before it is
+necessary to start off again with a fresh culture. A great deal depends
+on the care exercised and the freedom of the surroundings from bacterial
+germs. Under the best conditions wild germs will gradually accumulate in
+the soured milk, but their increase may be greatly delayed by attention
+to the precautions mentioned. The ordinary souring of milk for butter
+and cheese making is conducted in cool surroundings, as already stated,
+because in such conditions the lactic-acid-producing germs increase
+relatively faster than the wild germs, and so gain the upper hand, but
+in the case of our special soured milk we kill out, practically, all
+wild bacteria and germs, and the pure culture having the field to
+itself, we can conduct the operation at a higher temperature where the
+action of the bacteria is at its maximum, and so obtain the necessary
+lactification in the minimum of time.
+
+The appliances for the souring of milk on the domestic scale require
+some consideration. We propose to describe the principal forms of
+apparatus which have been put on the market for the purpose, and then to
+give such suggestions as may assist the ingenious in making apparatus
+for themselves. Those who wish for information on the subject of larger
+apparatus will find it in the following chapter.
+
+  [Illustration: FIG. 41--Photograph of Agar Culture,
+  inoculated with a lactic powder offered to consumers under
+  a fancy name. Working on the assumption that the presence
+  of lactic bacteria is inimical to the growth of septic
+  organisms, this preparation has been placed on the market.
+
+  The plate shows, however an abundance of colonies of
+  foreign organisms--sporogenous bacilli, _Staphylococcus
+  pyogenes albus_, and _Staphylococcus pyogenes aureus_.
+  These organisms are shown in the appended
+  photo-micrographs, and constitute impurities in the
+  preparation.]
+
+  [Illustration: Spore forming bacillus]
+
+  [Illustration: _Staphylococcus pyogenes albus_]
+
+  [Illustration: FIG. 42--Photograph of Test Tubes of Sterile
+  Milk, inoculated with a tablet preparation said to contain
+  pure cultures. The darker liquefied portion of the
+  tube-contents is due to digestion of the curd by
+  proteolytic bacteria, thus indicating impure culture. Pure
+  cultures of lactic acid bacteria coagulate the milk
+  uniformly, but do not produce any subsequent change in the
+  appearance of the culture, even after several months.]
+
+  [Illustration: FIG. 43--Photograph of Test Tubes of
+  Sterile Milk, each tube having been inoculated with a
+  tablet of a preparation said to contain pure cultures.
+  Here, again, there is evident peptonisation of the curd,
+  thus indicating infection by proteolytic ferments.
+  Cultures from these tubes demonstrated the presence of a
+  foreign organism. Microscopical examination failed to
+  disclose the presence of _Bacillus Bulgaricus_.]
+
+  [Illustration: FIG. 44--Photograph of Test Tubes of
+  Sterile Milk, inoculated with a tablet of
+  "Lactobacilline." In contra-distinction to those shown in
+  Figs. 42 and 43, these tubes exhibit homogeneous curdling
+  of the milk without any subsequent digestion or
+  peptonisation of the coagulum. This is indicative of the
+  purity of the culture.]
+
+The Society "Le Ferment" of Paris, which has been authorised by
+Professor Metchnikoff to prepare and supply to the public his sour milk
+culture, provides an apparatus for the treatment of the milk. It is
+shown in Fig. 45, which consists of a double box having the intervening
+space packed with a non-conducting material. It is provided with a
+tight lid. Inside, there is accommodation for two milk vessels, each
+with a capacity of about two thirds of a pint. The most difficult thing
+in the souring of milk is to maintain the temperature as nearly at 100 deg.
+F. as possible while the culture is in action. This result is attained
+by filling the vessel in the middle with boiling water. The insulated
+walls hinder the escape of heat, and the quantity of boiling water used
+is calculated to maintain the temperature steady for the twelve hours of
+cultivation; but in cold, frosty weather it is necessary to refill the
+central vessel with boiling water in the middle of the period.
+
+  [Illustration: FIG. 45]
+
+The milk jars are washed with hot boiled water and turned upside down to
+dry. They should not be wiped with a cloth. Boil the milk to be treated
+for ten minutes, stirring it to promote evaporation, as it is
+advantageous to have it in concentrated form. Cool rapidly to 100 deg. F.
+by placing the boiling vessel in cold water, add to each bowl one third of
+a tube of the culture in powder form, fill up with the boiled and cooled
+milk, stir well and cover. Place the jars in the box and fill the
+central vessel with boiling water, shut the lid tight, and do not open
+it (unless a fresh charge of boiling water is needed) for ten or twelve
+hours, when it will be ready for use. If the liquid culture is used (one
+small phial for each bowl) the milk should be cooled to 86 deg. F. instead
+of 100 deg. F., as with the powder. The culture is also supplied in tabloid
+form. The powder and tabloids keep well, but the liquid can only be
+relied on for about two months. The milk prepared as above should be
+stored in a cool place, the lids being kept on the bowls. It is good for
+about two days, after which it becomes too sour. It can be eaten with
+sugar, which not only sweetens it but is beneficial in affording
+additional suitable food for the acid-producing bacilli. If fresh milk
+cannot be had, condensed, sterilised, or pasteurised milk may be used,
+but, of course, fresh milk is best. Condensed milk should be diluted
+with two parts of boiling water and then treated like ordinary milk.
+
+An apparatus on similar principles is sold by the Maya Bulgare Company,
+Ltd., and is illustrated in Fig. 46.
+
+  [Illustration: FIG. 46--Soured Milk Apparatus of the Maya
+  Bulgare Company, Limited, consisting of an insulated box,
+  hot-water vessel, and covered vessels containing the milk
+  and culture. The apparatus consists of cabinet in deal,
+  Maya Bulgare ferment in 20-dose bottles, Maya Bulgare
+  ferment in 100-dose bottles, compressed Maya Bulgare
+  tablets in boxes of 8 tubes, Maya Bulgare caramels in
+  boxes of 40, reduced milk, china funnels, and
+  thermometers.]
+
+The box is insulated, but the door is on the side, the hot water vessel
+is underneath, and the covered vessels containing the milk and culture
+are placed on a shelf above. In the front of the illustration are shown
+the various packages in which the liquid and powder cultures are put up.
+The procedure is exactly the same as with "Le Ferment" apparatus.
+
+Lactic Ferments, Limited, make use of a different principle to maintain
+the temperature steady during the lactifying period. Their apparatus
+(Fig. 47) consists of a water vessel mounted on a stand. The milk
+vessels (tumblers) are placed in the water, and the temperature
+maintained at the proper figure by a small night light burning
+underneath. It is recommended that the milk should be placed in an
+earthenware jar or jug, which is stood in a pot of water kept boiling
+for an hour. After cooling add from three to six previously crushed
+tabloids of culture, and stir well with a glass rod which has been
+sterilised in boiling water. The milk is then transferred to three
+tumblers, which it should fill, and these are put into the water vessel,
+the water in which should be at about 100 deg. F., and the night light
+started.
+
+  [Illustration: FIG. 47]
+
+Messrs. Allen & Hanbury, Limited, also make use of the night light to
+maintain the proper temperature during incubation in their "Sauerin"
+apparatus (Fig. 48).
+
+No water, however, is placed in the metal container. The procedure is
+the same as that already described, and both tablet and liquid pure
+cultures are supplied. For children it is recommended that the
+incubation should occupy from three to four hours only, in other cases
+eight to ten hours. Grated nutmeg, ground cinnamon, or other flavouring,
+and cream may be used with the soured milk.
+
+The night light is also employed in the "Veronelle" apparatus of Messrs.
+Clay, Paget and Company, Limited (Fig. 49).
+
+  [Illustration: FIG. 48.--Messrs. Allen & Hanbury's Soured
+  Milk Apparatus. They maintain the temperature by means of
+  a night light, and the culture they use they call
+  "Sauerin."]
+
+  [Illustration: FIG. 49.--Vironelle Apparatus for souring
+  milk, made by Messrs. Clay, Paget & Company, Limited. The
+  milk in this case is placed in an earthenware jar, and is
+  sterilised by placing in a saucepan of water and boiling
+  it. The culture is added after cooling, the period of
+  incubation being about six hours.]
+
+The containing vessel is of tin or aluminium, and has two stands, the
+high one for hot and the low one for cold weather, as in the latter
+case greater heat is needed to maintain the incubating temperature. The
+milk is placed in an earthenware jar and is sterilised by placing it in
+a saucepan of water and boiling it; continuing the boiling for half an
+hour. It is allowed to cool to about 98 deg. F., and placed in the
+incubator, culture added, and the lamp lighted, the cover of the
+incubator being kept on. The period of incubation is given as six hours.
+To prepare the next day's supply a tablespoonful of the soured milk is
+retained and used instead of the culture. This may be continued for
+fourteen days, when a fresh start with culture is necessary. The soured
+milk will keep for thirty-six hours. Capacity, one and one half and two
+pints; also a large size for family use.
+
+For the preparation of soured milk on a small scale, one of the various
+forms of vacuum flasks now on the market may be used with satisfactory
+results. A little cold water must be poured into the flasks, and warm
+water added, until, by means of three to four changes, boiling water can
+be safely poured in without cracking the flask.
+
+This boiling water must be allowed to remain in for about twenty
+minutes, and then replaced by freshly boiled milk that has been cooled,
+so that its temperature in the flask is about 105 deg. F. The culture of
+lactic organisms should then be added, the opening of the flask plugged
+with clean cotton-wool, and the cap screwed on.
+
+In an actual test, the temperature of the milk placed in such a flask
+was 105 deg. F., at 7.30 P.M., and had dropped to 93 deg. F. by 9 A.M., the
+following day. The milk was curdled, and possessed the normal acid taste
+of such cultures.
+
+The different types of apparatus are all quite simple, and it would be
+easy to make something at home. Get two round tins, the one less in
+diameter by from two to three inches than the other, put one or two
+pieces of wood across the bottom inside the larger tin, and fill up the
+space between with cotton-wool, which is an excellent non-conductor of
+heat. Place the smaller tin centrally inside the larger one. Fix three
+or four distance pieces of wood in the space between them, fill up with
+cotton-wool, leaving a little space at the top to permit the lid of the
+smaller tin to be fixed on. The boiling-water vessel may be a tin
+saucepan with a lid, but no handle, and its proper place would be on the
+bottom of the inner tin. A tripod stand made of three pieces of wire
+bound together, and with legs reaching past the hot-water vessel to the
+bottom of the tin, would support a false bottom of tin forming the shelf
+on which the vessels of milk to be treated would rest. These might be
+tumblers covered with tin lids. To prevent radiation through the lid of
+the inner tin, a thick pad or hood of cotton-wool packed between cloth
+would be placed over the top. A little experimenting would be necessary
+to determine the quantity of boiling water required to maintain the
+proper temperature.
+
+The soured milk obtained in the above manner is of the consistency of
+ordinary buttermilk; a separation of whey frequently takes place, and
+this may be poured off if desired. The taste and flavour should be
+pleasantly acid and agreeable, and both are distinctive enough to give a
+good idea of the purity of the product. In many places a more
+concentrated article is made by boiling down the milk to one half or one
+third of its bulk, and then fermenting it in the ordinary way. A kind of
+thick pudding is thus obtained, which is highly recommended both as an
+agreeable article of food and as a stronger medium for the support of
+the germs it is the purpose of the sour milk treatment to introduce
+into the digestive system.
+
+The cultures for making soured milk can now be had from all the leading
+wholesale and retail chemists, with directions as to the quantities to
+be used.
+
+It is very necessary that the milk used should be not only fresh and
+good, but also free from chemical preservatives. The effect of these is
+to inhibit the growth and development of bacteria, and they have
+therefore an injurious influence on the special lactifying germs it is
+our object to cultivate. Preservatives are now not nearly so much used
+as they were, a few years ago, and there should be no difficulty in
+obtaining milk free from them.
+
+For keeping both fresh and soured milk good a small ice-chest is an
+excellent device. The germs which are continually dropping into milk
+kept in open vessels in the air, even in cleanly surroundings, are
+mostly kept out in the close ice-chest, and the low temperature prevents
+in a natural way the development of the bacterial germs already in the
+milk. For the preservation of all kinds of foods the ice-chest is a
+capital investment, not to mention the benefit of having cooled drinks,
+etc., as required. They manage things well in this respect in the United
+States, where ice is regarded as a necessity in the summer time by even
+the poorest people, and is delivered with the same regularity as the
+milk.
+
+It is necessary to utter a word of warning as to certain forms in which
+the sour milk bacillus is being offered to the public. It is being
+compounded with sugar, chocolate, and other articles, and sold in the
+form of sweets, etc. There is no reliable proof that these preparations
+are valuable. Certainly, sugar is a medium in which the lactifying germs
+can live, but the quantity so introduced into the system must be very
+small compared with what is obtained from properly fermented milk. It
+takes some time, even with strong cultures, to fix the acid-producing
+germs in the large bowel where they are wanted, and until proper
+evidence is forthcoming that confectionery preparations are efficacious
+we would recommend that only the regularly fermented milk be used. It
+would save trouble, no doubt, to treat oneself with a few chocolate
+creams containing the necessary germs daily, but if the matter is taken
+up seriously it will be better to take some pains and stick to methods
+the efficacy of which has been demonstrated, leaving the others until
+their _bona fides_ has been proved. There are always enterprising firms
+who are prepared to simplify things for us, but we must make sure that
+their simplifications are warranted.
+
+
+
+
+CHAPTER VII
+
+THE PREPARATION OF SOURED MILK IN THE DAIRY
+
+
+There is a tendency in certain medical quarters to discourage the use of
+soured milk "made for profit." This view leaves out of account the fact
+that besides being of value in medicine, the article in question is also
+an excellent food, which, as we have seen, has been consumed by
+multitudes of people for ages in many parts of the world. There seems
+also to be satisfactory evidence that a larger percentage than usual of
+the people who make soured milk a staple of diet attain to a ripe old
+age. How does it become such a dangerous thing the moment the doctors
+get it into their hands? Of course if a man has an acute disease he
+places himself entirely in the hands of his medical man, and eats what
+is prescribed for him, or at least he ought to do so, and if he makes
+such a submission he is entitled at least to the comfort of being able
+to feel that his doctor is free from unreasonable prejudices. For the
+implication that an article "made for profit" is naturally suspect casts
+an unwarranted stigma on a large number of honourable people. There are
+dishonest tradesmen just as there are dishonest and careless doctors,
+but to saddle a whole class with the offences of a few would not be a
+justifiable proceeding in either case. Besides, it is not to the
+interest of the manufacturing chemist or the dairyman to turn out
+spurious cultures or bad soured milk, and on the whole we see no reason
+why they should not engage in the business.
+
+The widespread use of soured milk in other countries as a regular
+article of diet seems to indicate that all manner of people, except
+those suffering from diseases which necessitate medical regulation of
+diet, might with probable benefit to themselves add this article to
+their food list; and it looks as if a good many of them intend doing so,
+even if scandalised doctors threaten "to abandon the cure."
+
+The dairyman who knows his business does not need to be told of the care
+which is necessary to keep milk in good condition. The merely commercial
+consideration of avoiding loss has made him ready to inquire into the
+best means of prolonging the life of milk as a merchantable article.
+For a time he relied on chemical preservatives, but their day is now
+almost over, and filtration, pasteurisation, and cold storage have taken
+their place. Any one conversant with the trade knows how widely these
+methods have been adopted of late years; we may, therefore, assume that
+the average dairyman has at his command milk suitable for the incubation
+process.
+
+The demand for soured milk is not as yet a very large one, and the
+apparatus so far developed for its production is meant for the treatment
+of small quantities. After describing the principal appliances at
+present in the market we propose to make some suggestions as to the
+construction of larger apparatus.
+
+A firm which has given great attention to the question of maintaining
+fixed temperatures is that of Messrs. Charles Hearson & Co., Ltd. Their
+incubators for chicken hatching are known all over the world; and their
+appliances for biological incubation are very generally used in
+bacteriological laboratories. With such experience it was natural that
+they should turn their attention to soured milk apparatus, and the
+result is the "Lactobator" (Figs. 50 and 51).
+
+  [Illustration: FIG. 50.--"Lactobator" made by Messrs.
+  Charles Hearson & Co., Limited, which is used for the
+  incubation of pure culture in milk in a fairly large way.
+  The illustration shows the "Lactobator" closed.]
+
+  [Illustration: FIG. 51.--Messrs. Hearson & Company's
+  "Lactobator," showing the internal arrangements.]
+
+A copper vessel made to contain water has placed in it a stoneware jar
+which holds two gallons of milk; on the top is a lid which carries a
+thermometer for indicating the temperature of the milk. Heat is supplied
+by a gas ring under the copper vessel; and in the gas supply is the
+patent thermostat made use of by Messrs. Hearson also in their
+biological and poultry incubators, in which a capsule containing a
+liquid arranged to boil at a certain predetermined temperature is the
+regulating factor. When the liquid boils, the capsule expands, and by
+certain mechanical devices regulates the gas supply so as to produce
+exactly the temperature required.
+
+The procedure is as follows: The jar is filled with milk, and water is
+run into the copper vessel by the funnel until it runs over at the
+overflow pipe. The thermostat is lifted off and the full gas supply
+allowed to pass to the burner, the temperature of the milk brought up to
+180 deg. F. and maintained for half an hour at this figure. The gas is then
+turned off, and cold water run through the funnel until the temperature
+of the milk registers 95 deg. F. The culture is added, the lid replaced,
+and the thermostat put into the pocket at the side of the vessel; the gas
+relighted, and when the temperature reaches 100 deg. to 106 deg. F. the
+capsule of the thermostat will expand and close the gas to a peep, which
+is just sufficient to maintain the temperature within the above limits.
+After eight hours the incubation is completed.
+
+Edgar's patent apparatus, the "Lactogenerator," as provided by the Dairy
+Supply Co., Ltd., is shown in Fig. 52.
+
+  [Illustration: FIG. 52. Edgar's "Lactogenerator"]
+
+The milk is placed in a tinned copper-jacketed vessel and water run in
+through a vertical pipe until it runs off at the overflow. Two gas
+connections are required with cocks on each, the one to heat up the milk
+to the boiling point and maintain it at this for thirty minutes. A
+skimmer which has been placed in the milk lifts out the coagulated
+protein and albumen which rise to the top. The cock is then shut and
+cold water run through the jacket till the thermometer shows 90 deg. F.,
+when the culture is added, and the other gas supply with the regulator
+turned on, and the temperature is automatically maintained at about 90 deg.
+F. Time of incubation eight to nine hours. It is recommended to turn
+cold water into the jacket at the end of the period to prevent
+overincubation.
+
+A somewhat similar apparatus is that of the Willows Refrigerating Co.,
+Ltd. (Fig. 53), with the exception that it has no automatic heat
+regulator. It is made of tinned steel, and the operations are the same,
+but the sterilising temperature (obtained by a gas ring or hot plate) is
+given as 180 deg., and the incubating temperature 100 deg. to 104 deg. F.
+for a period of twelve hours. Presumably this temperature is maintained
+by a small gas jet or other similar source of heat. The capacity is two
+gallons.
+
+  [Illustration: FIG. 53
+
+  Apparatus of the Willows Refrigerating Co., Ltd.]
+
+In the apparatus hitherto described the milk is sterilised in bulk, and
+is filled into bottles or jars after incubation, which is not a
+desirable thing to do, unless the soured milk is for immediate
+consumption, as there is likely to be contamination with injurious germs
+from the atmosphere. In the domestic apparatus the milk is usually
+incubated in covered jars in which it can be kept until required for
+use, and the practice on the larger scale should be the same.
+
+The Dairy Outfit Co., Ltd., have recognised this in their "Lacto"
+apparatus (Fig. 54).
+
+  [Illustration: FIG. 54
+
+  "Lacto" Apparatus of the Dairy
+  Outfit Co., Ltd.]
+
+A cylindrical vessel is set loosely on a stand, beneath which is a lamp
+calculated to maintain the incubating temperature. The milk is placed in
+bottles with metal screw tops, and these are put into the cylindrical
+vessel; water is run in round them through the side funnel, the vessel
+lifted off the stand, and heated to sterilising point on a stove. Cold
+water is then run in through the funnel until the temperature is low
+enough for incubation. Culture is added to each bottle and the lids
+screwed on, the vessel lifted on to its stand, and the lamp lighted. The
+cover of the apparatus has a thermometer fixed on it.
+
+On the large scale the treatment of the milk would take place entirely
+in the jars in which it would be sent out, and the sterilisation and
+incubation would be conducted in different pieces of apparatus. The
+sterilisation would be effected either (1) by direct steaming, or (2) by
+hot water heated by steam. Fig. 55 shows the first type of
+sterilisation. The tank is of wrought iron or steel with strengthening
+pieces of angle iron. The door, with pulleys and counterweight for easy
+handling, is fastened steam-tight by hinged bolts. The apparatus is
+mounted on a stand at a convenient height for handling the bottles; and
+in front is another stand with channel iron rails to take the waggon in
+which the bottles or jars to be sterilised are packed. When the door is
+fast, steam is turned on, and regulated to produce the proper
+temperature by the thermometer fixed in the shell, in which a pressure
+gauge is also secured. After sterilising, the door is opened and the
+waggon drawn forward to the outside, allowed to cool, or removed
+elsewhere to cool, and allow space for a new charge.
+
+  [Illustration: FIG. 55.--Sterilising Apparatus for
+  sterilising milk on the large scale. The bottles of milk
+  are sterilised, and the culture can then be added, and the
+  incubation allowed to proceed in an insulated chamber.]
+
+The second method of sterilising is by hot water, as in Fig. 56. The
+bottles or jars are placed on a perforated false bottom in the
+rectangular tank, water run in up to the necks, and steam turned on; the
+lid is fastened with hinged and hooked bolts; a thermometer fastened in
+the lid, and with a long stem enclosed in metal, indicates the
+temperature. At the end of the sterilising process cold water is turned
+on, and at the same time the overflow water cock is opened; the cold
+water gradually reduces the temperature, and the incubating point is
+quickly reached.
+
+  [Illustration: FIG. 56 Another Method of Sterilising
+  (Dairy Supply Co., Ltd.).]
+
+Incubation in bottles or jars, sterilised in these ways, can best be
+conducted in an insulated room, with say, six inches of silicate cotton,
+granulated cork, or washed cow hair packed between two-inch by six-inch
+battens, covered with matching on either side, and lined with sheet
+zinc. It would be an advantage to have an air-lock or anteroom into
+which the waggons or trays of sterilised jars could be run, and the door
+of the anteroom closed before the door of the insulated room is opened.
+This would tend to prevent variations of temperature in the room, and
+also, by checking free communication with the outside air, decrease
+contamination. The waggons of jars would be run in, and culture added to
+each jar by a sterilised pipette. The atmosphere of the room would be
+kept pure by running in air frequently through a filter of moist
+cotton-wool by means of an electric fan, and at intervals the interior
+would be sterilised by the use of formalin vapour.
+
+
+  [Illustration: _Details of an American Apparatus for
+  Preparing Soured Milk_
+
+  FIG. 57
+
+  The figures give diagrams A, B, C, and D of an apparatus
+  useful for the preparation of lactic foods. The incubating
+  can A, is made of block tin, and is intended to contain
+  the milk. B, the warm water container, should be a stout
+  walled vessel with a circular aperture in the lid, through
+  which the incubating can may be passed, and clamped down
+  as in C.
+
+  B is fitted with three stout iron legs, which should be
+  sufficiently long to allow of a small lamp or gas-jet
+  being placed beneath the container to maintain a uniform
+  temperature.
+
+  D gives an external view of the apparatus.
+
+  For the preparation of soured milk, separated milk is
+  placed in the incubating can, and heated up to 100 deg. C.
+  (212 deg. F.) for thirty minutes. It is then allowed to cool
+  to room temperature, and the culture, or tablet containing
+  the lactic acid bacteria, is then added, and thoroughly
+  stirred for a minute or so. The can is then immersed in
+  the warm water container and kept at a temperature of 86 deg.
+  F. to 104 deg. F., according to the organisms used, for ten to
+  twelve hours. By the end of this time the milk ought to be
+  converted to a jelly-like mass, and after being stirred
+  vigorously for a short time, may be cooled on ice, and is
+  then ready for consumption.]
+
+The incubating temperature could very conveniently be maintained by an
+electric radiator, and as the insulation would largely prevent leakage,
+the amount of electric current used would not be large. The regulating
+apparatus might consist of a thermometer with platinum wires fused
+through the stem at the proper temperature, say 100 deg. F. When the
+mercury rises to this figure it will complete the circuit of a battery
+which will actuate certain well-known devices for turning off the current
+which actuates the radiator. In this way a very fine automatic
+arrangement would be achieved. Steam pipes might be used instead of the
+radiator, and the thermometer above described could be used in this case
+also, with appliances to cut off the steam.
+
+On the large scale, labour-saving appliances, such as the mechanical
+brush jar and bottle washer, and the automatic filler for jars or
+bottles, would be employed, and an overhead trackway for carrying the
+trays of jars from the steriliser to the incubator would be a great
+convenience. A further adjunct of considerable importance would be a
+cold room, worked either by ice or a refrigerating machine, in which the
+jars could be stored after incubation, so as to arrest the process of
+lactification, and maintain the soured milk in good condition until
+required for use.
+
+
+
+
+CHAPTER VIII
+
+SOURED MILK IN HEALTH AND DISEASE
+
+
+When people are ill the best thing they can do is to place themselves in
+the hands of the doctor, who will try to regulate their lives, including
+their diet, in accordance with the conditions which science suggests as
+the most likely to lead to their recovery.
+
+It is not the aim of this book to teach persons who should be under
+medical treatment to doctor themselves; soured milk may or may not be
+beneficial in their case--that is for the medical man to say; and
+further, if it should be beneficial the doctor ought to have its
+preparation under his control. Slight differences in quality and purity
+may count for much in cases of acute disease, differences which might
+not matter to the person who requires no medical attention, and who
+consumes the article as a health-giving food. A considerable body of
+evidence is already on record as to the potency in certain cases of
+soured milk as a curative agent, and it seems to have taken its place in
+medicine as a recognised remedy.
+
+There is a wide field of usefulness, however, outside of the strictly
+medical one. Professor Metchnikoff has collected many striking examples
+of individuals and peoples inhabiting different parts of the world, who
+thrive, and in many cases attain to a great age, and whose diet consists
+largely of soured milk. He has made a wide and general inquiry into the
+causes which tend to shorten life, and makes out a strong case in
+support of the view that in many cases this is the result of what is
+called auto-intoxication or self-poisoning. In man and in the mammalia
+generally, the colon or large intestine is very largely developed; this
+organ is not of much value in the digestion of food, and seems to be
+chiefly a receptacle for waste material; it is, as a rule, extremely
+rich in bacterial flora, which produce putrefactive changes in the waste
+material. As a result various poisonous principles are evolved, and
+these find their way into the blood, accompanied frequently, there is
+every reason to believe, by the injurious bacteria themselves. In this
+way many diseases and ailments are produced which shorten life. The
+inquiry then naturally turns to what is the best way of dealing with
+this state of matters. It is known that the bacteria referred to
+flourish best in alkaline or at least non-acid surroundings, and it is
+known that these conditions very frequently exist in the large
+intestine. Acids are the best antiseptics; they have been used from time
+immemorial as preservatives; pickles are preserved in vinegar or acetic
+acid, and when milk is allowed to sour under proper conditions, the
+germs of putrefaction are destroyed or their activity inhibited, and it
+keeps a considerable time. Doubtless, in hot countries, it was this
+property of lactic acid which first led to milk being artificially
+soured with a view to its preservation as an article of food. So
+powerful is lactic acid in this respect that it is a custom in some
+countries to preserve meat by placing it in soured milk.
+
+How can acids be applied so as to control the bacterial flora of the
+large intestine? Not in the ordinary way, because, when administered
+through the mouth, they are used up long before they can penetrate to
+the colon. The brilliant idea occurred to Professor Metchnikoff, of
+administering acid-producing germs which might work their way through
+the digestive system, and, reaching the large intestine, produce the
+acid required. After much experimenting the bacillus of Massol,
+_Bacillus bulgaricus_, was adopted as the most suitable. The Bulgarian
+bacillus is an extremely vigorous one, multiplying with great rapidity,
+and persisting in conditions that would be inimical to other microbes.
+The growth and development of bacteria is interfered with by the
+products of their own activity; thus, ordinary lactic-acid-producing
+organisms die when a certain amount of lactic acid has been developed;
+the same fate overtakes the Bulgarian bacillus, but it survives longer
+and is able to produce as much as two and one half per cent. of lactic
+acid in milk before it ceases operations. It seemed therefore the most
+likely to be able to survive the journey through the digestive system.
+Experiments fully bore out this supposition, as no great difficulty was
+encountered in naturalising the Bulgarian bacillus in the large
+intestine, not only in milk cultures, but grown in solution of malt,
+bouillon, etc. It thrives in all kinds of sugar, and therefore can be
+administered in a variety of media, very beneficial results following in
+many cases. Direct tests showed a large reduction of the injurious
+intestinal flora when the Bulgarian bacillus had been naturalised in
+the colon, and the bacillus persisted long after it had ceased to be
+administered. Specialists who have taken up the subject report the cure
+of many ailments through the agency of soured milk, and it seems to have
+entered upon a lengthening career of medical usefulness.
+
+The fact of so many old people being found in countries where soured
+milk is a staple of diet naturally raises the question as to whether its
+general use in other countries might not have a beneficial effect on
+health and longevity. Its usefulness as a remedial agent in certain
+diseases is already demonstrated; is there not a strong probability,
+amounting almost to a certainty, that its consumption by people in
+health would tend to ward off many ailments and prolong life? Of course
+there will be some for whom it is not suitable; there are people who
+cannot eat strawberries without discomfort, but no one thinks of
+prohibiting the general use of the fruit on that account. In the matter
+of diet the person in health, if he exercises ordinary care, may be left
+to find out for himself what suits him. The soured milk remedy is not a
+disagreeable one, as, when properly prepared, the article forms both a
+pleasant and refreshing article of diet. The question of getting the
+right article, however, is a very important one. Milk is a splendid
+rearing ground for many bacteria, some of which are very injurious;
+among these may be pathological germs, the seeds of tuberculosis,
+enteritis, etc. The danger with soured milk is, that in the process of
+culture we develop the best condition for the increase of these when
+they preponderate, or when, through the use of bad cultures, the
+lactic-acid-producing bacteria are absent, or present only in small
+numbers. By the thorough boiling of the milk, we get rid of all living
+bacteria and nearly all spores or germs, and by scrupulous cleanliness
+in the vessels used--scalding or even boiling them, and allowing them to
+dry naturally in an inverted position--we greatly diminish the
+probability of infection with fresh injurious germs from the atmosphere.
+All depends on the purity of the culture employed; this can now be
+obtained, prepared in the most careful manner, from wholesale chemists
+making a speciality of its manufacture.
+
+As we have seen, even the Bulgarian bacillus is ultimately killed by the
+products of its own activity, and the natural corollary is, that the
+life of cultures cannot be a long one. Only those cultures should be
+bought which are labelled with the date to which they are guaranteed to
+maintain their efficiency. With fresh good milk, careful boiling,
+scalding, and cleanliness with regard to the containing vessels, and the
+means of maintaining the incubating temperature for ten or twelve hours,
+there is not the slightest difficulty in preparing perfectly reliable
+soured milk. There are simple tests which will sufficiently guide the
+experimenter; the soured milk should not be too acid to the taste, and
+it has a flavour of its own by which its quality can be recognised. The
+litmus test-papers mentioned in the chapter on the chemistry of milk are
+very useful; both the red and the blue papers should be obtained and
+used first of all in testing the quality of the fresh milk. After
+incubation the soured milk should turn the blue paper decidedly red; if
+this does not occur, test it with the red paper; if the latter turns
+blue it is proof that the wrong fermentation has taken place--that
+putrefactive germs have gained the upper hand. The most probable
+explanation is, that the culture is bad, the Bulgarian bacillus is not
+present, or if so, only in small numbers. With these simple tests,
+combined with proper care, one cannot go far wrong. The Eastern nations
+who prepare soured milk in various forms do not exercise the care we
+have predicated, but they seem to make the article of fairly constant
+and good quality. It has been suggested in explanation that, as the
+ordinary flora differs in different countries, the bacterial flora
+varies in a similar manner, and that in these Eastern countries
+injurious bacteria are not so prevalent in the atmosphere as they are
+with us.
+
+It is also said that the flavour of the soured milk prepared in Bulgaria
+is quite different from that prepared in Paris, London, or New York; one
+reason probably is that the "maya" or ferment used in Bulgaria contains
+several other organisms besides the Bulgarian bacillus, which raises the
+question whether a pure culture of one bacillus is the best to use.
+
+Professor Metchnikoff found that this bacillus alone had certain
+defects; it attacks fat and is apt to give a tallowy taste when cream is
+present in the milk. He therefore associated with it another
+lactic-acid-producing organism, and this combination is the basis of his
+culture called "lactobacilline." The presence of yeasts, which occur in
+the Eastern ferments, has been advocated by some; the yeast in
+association with the lactic organisms produces a small amount of
+alcohol. The question of the composition of the culture will have to be
+fought out by the experts, but meantime, if we go to the right source,
+we have good enough cultures to go on with.
+
+A good deal can be said for the use of skimmed or separated milk instead
+of whole milk. Cream as a rule contains far more bacteria than the rest
+of the milk, and we therefore start from a surer foundation when it is
+removed; besides, the mechanical separator, now so largely used, removes
+slime and other impurities from the milk, and these also are hotbeds of
+bacteria.
+
+Soured milk may be taken at any time, the first thing in the morning,
+before or after meals, or the last thing at night. The quantity will
+vary with the individual, but from half a pint to a pint is a fair
+amount for daily use. If one wishes to have the maximum effect it is
+necessary for the time being to curtail the use of butcher's meat and
+substitute fish, yolk of eggs, and other similar foods; not much alcohol
+should be taken, and smoking might be reduced to a minimum. Those who
+cannot take even skimmed milk may use whey in which to cultivate the
+bacillus; it is not desirable to employ the whey which has been
+separated by the use of rennet, as in cheese- or junket-making. A better
+article is obtained by adding a very small quantity of pure hydrochloric
+acid to milk which has been boiled, and then filtering through a sieve,
+which retains the curd while the liquid whey passes through; a pinch of
+soda is added to neutralise the excess of acid, and, after boiling, the
+liquid should turn red litmus paper blue; it is then ready for the
+addition of the culture and incubation in the same manner as with milk.
+A solution of malt--the extract dissolved in hot water is
+convenient--may also be used instead of milk, and strongly malted bread
+or biscuits are excellent to take with the soured milk or cultures in
+other mediums, to supply food for the bacillus in the form of malt
+sugar. Other sugars, cane or grape, are also very useful, and may be
+taken in the form of fruit juices, syrups, confections, jams, sweet
+puddings, etc.
+
+We lay stress on the use of soured milk or other cultures of the
+Bulgarian bacillus by people in health as a probable preventive of
+disease and a possible agent in the lengthening of life, but it may be
+of interest to give a short account of its use by medical men in the
+treatment of various ailments. An English authority on the subject, Dr.
+Herschell, states that the symptoms of the poisoning of the system by
+the toxic substances produced by injurious bacteria in the large
+intestine may include headaches, misery and depression of spirits,
+drowsiness and stupor, giddiness, dimness of sight and dizziness,
+fatigue without obvious cause, both of the muscles and brain, fear,
+panic, and nervousness, disagreeable sensations in the limbs or face,
+such as numbness, tingling, or prickling, crawling sensation of weight
+or of heat or cold, dyspepsia of the sort where there is a deficiency of
+hydrochloric acid and pepsin in the gastric juice, accompanied by
+flabbiness and loss of power in the muscles of the stomach, and
+characterised by flatulence, nausea, loss of appetite, with discomfort
+and weight after food, furred tongue, emaciation, earthy colour of the
+skin, offensive perspiration and the other signs of biliousness,
+enlargement of the liver, and anaemia. These symptoms may have other
+causes, and when one or several of them are present a chemical and
+physical examination of the urine and faeces is necessary to prove that
+they have resulted from auto-intoxication. When this is shown the
+soured milk treatment is indicated, and many striking cures are detailed
+as witnesses to its efficacy. The liver and kidneys are the natural
+guardians of the body against the toxines we are speaking of, and
+frequently they are over-strained; the soured milk treatment greatly
+lightens their load. In malignant disease of the stomach, soured milk
+will frequently be retained when all other foods are rejected. In cases
+of neurasthenia and gout it has also proved of value, and in the
+"run-down" condition which is so common in middle life. Chronic
+diarrhoea and certain forms of constipation have in numerous instances
+yielded to the treatment, the whey culture being usually found the most
+suitable. Then, in some forms of anaemia, the lactic acid cultures have
+proved most successful, and, as a means of rendering the
+gastro-intestinal track aseptic previous to operations, they have proved
+of considerable value.
+
+If all this has been accomplished in a year or two, what may not we look
+forward to in the future when more extended use and experiment shall
+have more fully exhausted the possibilities of the cure? But if we
+follow the example of the different nations who have so long used
+soured milk as a regular article of diet, does it not seem probable that
+we may eliminate some, at least, of the causes of ill-health that call
+for the intervention of the doctor?
+
+The human organism is by no means perfect; we have within us many
+defective parts, and some organs whose working seems to be against the
+welfare of the economy. It has now been clearly shown that one of the
+chief of these is the large intestine, as to the use of which only vague
+and unsatisfactory theories have been formed. There can be no doubt as
+to the damage which it frequently inflicts on the system, and, thanks to
+the researches of Professor Metchnikoff and other investigators, we seem
+to be in possession of a natural remedy which is sufficient to deal with
+the evils it produces.
+
+
+  FOOTNOTES:
+
+  [1] _Discoveries in Nineveh and Babylon_, by Layard, chap.
+  xiii.
+
+  [2] Ex. xviii. and xxiii.; Lev. ii. and xi.
+
+  [3] _Encyclo. Biblica._
+
+  [4] Burckhardt and Doughty.
+
+  [5] _Annals of Dairying in Europe_, by Loudon M. Douglas.
+
+  [6] Burckhardt, _Bedouins_.
+
+  [7] This word is spelt in a great many ways by different
+  writers: _Yoghourt_ would seem to be the one most
+  favoured.--AUTHOR.
+
+  [8] _Damascus and Palmyra_, by Chas. G. Addison, 1838.
+
+  [9] _Travels in Syria and the Holy Land_, by Burckhardt,
+  1822.
+
+  [10] _Lands of the Saracens_, by B. Taylor.
+
+  [11] _Travels through Sweden, Finland, and Lapland and to
+  the North Cape in the years 1798 and 1799_, by Joseph
+  Acerbi, 1802.
+
+  [12] Letter to the author, from Mr. H. Cavendish Venables,
+  British Vice-Consul at Varna.
+
+  [13] _One Hundred and Twenty Years of Life_, by Reinhardt;
+  _The Secret of Longevity_, by an F.R.M.S.
+
+  [14] _Foods, their Composition and Analysis_, by A. W.
+  Blyth.
+
+  [15] _Dictionary of Applied Chemistry_, by T. E. Thorpe,
+  C.B.
+
+  [16] _Koumiss or Fermented Mares' Milk and its Uses, and
+  the Treatment and Cure of Pulmonary Consumption and Other
+  Diseases_, by L. Carrick, M.D., 1881.
+
+  [17] _Transactions of the Royal Society of Edinburgh_,
+  vol. i.
+
+  [18] Clarke's _Travels_, 1810.
+
+  [19] 1845.
+
+  [20] _Dictionary of Applied Chemistry_, by Thorpe.
+
+  [21] A leathern bottle.
+
+  [22] "I have brought forward Tchembulatof's receipt, which
+  differs from Bogoyavlensky's in the use of a larger
+  quantity of millet-flour, and in the boiling of the latter
+  apart from the milk. Dr. Postnikof's plan is the
+  following: Half a pound of millet-flour and a quarter of a
+  pound of malt are mixed with a sufficient quantity of
+  honey to form a paste, which is put into a clean jar,
+  covered with a linen cloth, and placed on a warm stove.
+  The mass soon begins to rise, and is then taken out,
+  wrapped in a piece of muslin, and dropped into a clean
+  earthenware vessel, containing about a quart of new mares'
+  milk, which is placed in the same temperature that the
+  paste was kept in. As soon as signs of fermentation begin
+  to show themselves in the fluid, the paste must be
+  removed, while the milk, after being stirred, should be
+  left in the same temperature till bubbles appear (only in
+  very small quantities) on its surface. The ferment is then
+  ready."
+
+  [23] _Food and the Principles of Dietetics._
+
+  [24] _Food and the Principles of Dietetics_, by Robert
+  Hutchison, M.D.
+
+  [25] _Bacteria in Milk and its Products_, by Conn.
+
+  [26] _Dict. App. Chem._, Thorpe.
+
+  [27] _Nature_, July 23, 1884.
+
+  [28] _The Exploration of the Caucasus_, by Duncan W.
+  Freshfield, 1896.
+
+  [29] Quoted by George M. Sternberg, M.D., LL.D.,
+  _Text-Book of Bacteriology_, 1898.
+
+  [30] _Encyclo. Biblica._
+
+  [31] Conn.
+
+  [32] _Cyclo. of Biblical Lit._, M'Clintock and Strong, and
+  Burckhardt's _Arabia_.
+
+  [33] _The Indian Medical Gazette_, Sept., 1909, "A New
+  Lactic Acid producing Streptothrix," by Gopal Ch.
+  Chatterjee, M.B.
+
+  [34] In their studies on Leben in the _Annales de
+  l'Institut Pasteur_ of 1899, Rist and Khoury, in speaking
+  of the amount of lactic acid produced by _Streptobacillus
+  lebenis_ in milk, say "Nous avons mesure cette acidite
+  dans une culture sur petit lait de vingt-quatre heures;
+  elle etait .261 grms. per cent. exprimee en acide
+  lactique," which will make the amount of lactic acid
+  produced in one litre of milk 2.61 grms. The production of
+  this small amount of lactic acid does not tally with the
+  ordinary view of the vigorous lactic-acid-producing power
+  of the bacillus.
+
+  [35] _Prolongation of Life._
+
+  [36] _Prolongation of Life._
+
+  [37] An accurate census of Bulgaria is being prepared and
+  will exhibit the cases of long life in that country.
+
+  [38] See A. Rosam, _Oesterreichische Molkerei Zeitung_, 15,
+  p. 31.
+
+  [39] _Revue generale du Lait_, vii., pp. 8 and 9 (letter
+  from Dr. Otakar Laxa of Prague, Bohemia, to the author).
+
+  [40] _On the Prolongation of Human Life_, by Elie
+  Metchnikoff; also _The Century Magazine_, Nov., 1909, "The
+  Utility of Lactic Microbes," by the same author.
+
+  [41] _Century Magazine_, Nov., 1909.
+
+  [42] See _Annals of Dairying in Europe_, by Loudon M.
+  Douglas.
+
+  [43] Adapted from a report by Robert E. Turnbull, in _Live
+  Stock Journal_.
+
+  [44] _Facts about Milk_, by R. A. Pearson, B.S.,
+  Washington.
+
+  [45] _Care and Handling of Milk_, Marshall and Wright,
+  Bulletin 221, Michigan, 1904.
+
+  [46] _Journal of the Royal Society of Arts_, March 6,
+  1908--"Modern Dairy Practice," by Loudon M. Douglas.
+
+  [47] Skolotowski, _Wratsch_, 1883 (Russian), from
+  Codwyssozki.
+
+  [48] Podowyssozki, _Zeitschr. f. diat. u. physik.
+  Therapie_ vol. v., 1901, p. 570.
+
+  [49] Hammersten, _Jahresb. u. d. Fortsch. d. Tierchem_,
+  1886, Bd. 16, p. 163.
+
+  [50] Essaulow, _Dissert. Moscow_, 1895, _Abstr., Koch's
+  Jahresb._, 1895, Bd. 6, p. 222.
+
+  [51] Kern, _Bulletin Soc. des Naturalistes de Moscow_,
+  1881, 3, p. 141.
+
+  [52] Krannhals, _Deutsch. Arch. f. Klin. Med._, 1884, Bd.
+  35, p. 18.
+
+  [53] Beijerinck, _Centralbl. Bakt. Par._, 1889, Bd. 6, p.
+  44.
+
+  [54] Scholl, _Die Milch_, Wiesbaden, 1891, p. 38.
+
+  [55] Adametz, _Centralbl. Bakt. Par._, 1889, Bd. 5, p.
+  116.
+
+  [56] Freudenreich, _Landw. Jahrb. d. Schweiz._, 1896, vol.
+  x., p. 1.
+
+  [57] Nikolaiewa, _Annals of the Botan. Lab. of the Med.
+  Inst. for Women_, No. 10. St. Petersburg, 1907.
+
+  [58] Kuntze, _Centralbl. Bakt. Par._, 1909, 24, p. 101.
+
+  [59] See Chap. II.
+
+  [60] Rubinsky, _Centralbl. Bakt. Par. II._, 1910, vol.
+  xxviii., p. 161.
+
+  [61] Biel, _Jahresb. ue. d. Fortschr. d. Tierchem_, 1886,
+  16, p. 159.
+
+  [62] Allik, _Dissertat. Dorpat._, 1896, 19, p. 303.
+
+  [63] Fleischmann, _Lehrb. d. Milchwirtschaft_, 2d edition.
+  Bremen, 1898.
+
+  [64] Rist and Khoury, _Annal. Pasteur_, 1902, 16, p. 65.
+
+  [65] Guerbet, _Comptes Rendus_, 1906.
+
+  [66] Weigmann, _Lafar's Handb. d. Techn. Mykol._, 2d
+  edit., 1905, vol. ii., p. 134.
+
+  [67] Emmerling, _Cent. Bakt. Par._ 1898, vol. iv., p. 418.
+
+  [68] Lindner, _Mikroscop. Betriebscontrolle, i. d.
+  Gaerungsgew_, 3d edit., Berlin, 1901.
+
+  [69] Kalantharianz, _Dissert. Berlin_, Abs. in _Koch's
+  Jahresb._, 1898, Bd. 9.
+
+  [70] Luerssen and Kuehn, _Centralbl. Bakt._
+
+  [71] Piorkowski, _Sitzungsber. der Berl. med. Ges._, Nov.,
+  1907.
+
+  [72] Metchnikoff, _The Prolongation of Life._
+
+  [73] Grigoroff, _Revue Medicale de la Suisse Romande_,
+  1905, p. 10.
+
+  [74] Grixoni, _Abstr. Cent. Bakt. Par._ 11, 15, p. 750.
+
+  [75] Freudenreich and Jensen, _Cent. Bakt. Par._ 11, 1897,
+  3, 545.
+
+  [76] Moro, _Wien. klin. Wochenschr._, 5, 1900.
+
+  [77] Makrinoff, _Cent. Bakt. Par._ 11, 1910, vol. xxvi.,
+  p. 374.
+
+  [78] White and Avery, _Cent. Bakt. Par._ II, 1909, vol.
+  xxv., p. 161.
+
+  [79] Hastings and Hammer, _Research Bull., Wisconsin
+  Experimental Station_, 6, 1909.
+
+  [80] Boutroux, _Comp. Rend._, 86, 1905, 605.
+
+  [81] Richet, _Comp. Rend._, 86, 1905, 550.
+
+  [82] Koning, _Milchw. Zentralbl._, 1905, 1, 280.
+
+  [83] Heinemann, _Centralbl. Bakt. Par._ 1908, 21, 57.
+
+  [84] Chap. I.
+
+  [85] Metchnikoff, _The Prolongation of Life_, 1908, p.
+  161.
+
+
+  INDEX
+
+
+  A
+
+  Acerbi, 8
+
+  Acidity of milk, 64
+
+  Adametz on keffir, 92
+
+  Albumen, 52
+
+  Alcoholic fermentation, 17, 84
+
+  Allen & Hanbury's apparatus, 132
+
+  American incubating apparatus, 149
+
+  Analysis of milk, 48, 61
+
+  Aneyza Bedouins, 2
+
+  Arabs, 2
+
+  Araka, 106
+
+  Ash of milk, 56
+
+
+  B
+
+  _Bacillus acidi lactici_, 107, 112
+
+  _Bacillus acidophilus_, 110, 112
+
+  _Bacillus bulgaricus_, 39, 46, 82, 108, 110, 123, 154
+
+  _Bacillus casei_, 113
+
+  _Bacillus caucasicus_, 92, 94, 95, 119
+
+  _Bacillus caucasina_, 39
+
+  _Bacillus coli_, 45
+
+  _Bacillus esterificans_, 96
+
+  _Bacillus keffir_, 96, 97
+
+  _Bacillus lebenis_, 105
+
+  _Bacillus matzoon_, 109, 110
+
+  Bacillus of long life, 46
+
+  _Bacillus putrificus_, 122
+
+  _Bacillus subtilis_, 90, 92, 107
+
+  Bacteria in milk, 76
+
+  Bacteriology of fermented milks, 84
+
+  _Bacterium acidi lactici_, 92, 96
+
+  _Bacterium aerogenes_, 92, 96
+
+  _Bacterium coli commune_, 119, 122
+
+  _Bacterium sardous_, 110, 111
+
+  Balkan Peninsula, 4
+
+  Bedouins, 2
+
+  Beijerinck on keffir, 91
+
+  Biestings, 63
+
+  Biology of the keffir grain, 90
+
+  Blood, water contents of, 50
+
+  Bourgoul, 6
+
+  Bulgarian maya, 10, 109
+
+  Bulgaricus group, cultural characteristics of, 115
+
+  Burckhardt, 6
+
+  Butin, 51
+
+  Butyric acid fermentation, 16
+
+  Butyrin, 51
+
+
+  C
+
+  Camels' milk, 2
+
+  Caprinin, 51
+
+  Capronin, 51
+
+  Caprylin, 51
+
+  Carrick on koumiss, 18
+
+  Casein, 52, 53
+
+  Centenarians in Servia, Bulgaria, and Roumania, 41
+
+  Chatterjee on Dadhi, 38
+
+  Chemistry of milk, 47
+
+  Chocolate preparations and the soured-milk bacillus, 137
+
+  Citrates in milk, 57
+
+  Clay, Paget & Company's apparatus, 132
+
+  Coagulation of casein, 59
+
+  _Colitis_, 45
+
+  Colostrum, 63
+
+  Constituents of milk, 48
+
+  Continuous apparatus for producing soured milk, 81
+
+  Creamometer, 62
+
+
+  D
+
+  Dadhi, 15, 38
+
+  Dairy Machinery & Construction Company's apparatus, 80, 82
+
+  Dairy Outfit Company's apparatus, 145
+
+  Dairy Supply Company's apparatus, 143;
+    steriliser, 148
+
+  Dirt in milk, 63
+
+  Diseases of keffir grains, 97
+
+  _Dispora caucasia_, 34, 90
+
+  Dried sour milk, 5
+
+  Duclaux, 51
+
+
+  E
+
+  Edgar's "Lactogenerator," 143
+
+  Eggs, yolk of, 52
+
+  _Enteritis_, 45
+
+  Enzymes in milk, 57
+
+  Equipment for town's dairy, 80
+
+  Essaulow on keffir, 89, 92
+
+
+  F
+
+  Fat of milk, 50
+
+  Ferments at the altar, 3
+
+  Fluegge, 35
+
+  Freshfield on keffir, 33
+
+  Freudenreich, 92
+
+
+  G
+
+  Gaseous fermentation, 84
+
+  Gay-Lussac, 17
+
+  Gioddu, 107
+
+  Globulin, 54
+
+  Grieve, Dr. John, on koumiss, 19
+
+
+  H
+
+  Hammerstein on keffir, 89
+
+  Handling of milk, 68
+
+  Health and disease, 151
+
+  Hearson & Company's "Lactobator," 141
+
+  Hebrews, 3
+
+  Houran, inhabitants of, 6
+
+  Hueppe, 16
+
+  Hutchinson, Dr. H. B., bacillus from English market milk, 120
+
+  Hutchison on koumiss, 30
+
+
+  I
+
+  Ice chest, 136
+
+  Impure cultures, 158
+
+  Incubators, 141
+
+  India, 1
+
+  International Dairy Federation, 68
+
+
+  J
+
+  Jebours, 3
+
+
+  K
+
+  Kalmucks, 20
+
+  Keffir, 15, 32, 85;
+    old, 88
+
+  Keffir grain, biology of, 90
+
+  Kephir, 34, 85.
+    _See also_ Keffir.
+
+  Keshk, 6
+
+  Keshk-leben, 6
+
+  Koumiss, 15, 18;
+    Bogoyavlensky's method of preparation, 28, 98;
+    analysis, 102;
+    artificial, 102
+
+  Krannhals on keffir, 91
+
+  Kuntze, 95
+
+
+  L
+
+  Lactic acid, bacillus, 16;
+    cultures, 55;
+    fermentation, 16, 84;
+    Ferments apparatus, 131
+
+  "Lacto" apparatus, 145
+
+  "Lactobacilline," 158
+
+  _Lactobac. caucasicus_, 91
+
+  _Lactobacillus keffir_, 94
+
+  Lactometer, 64
+
+  Lapland, 8
+
+  Laurin, 51
+
+  Layard, 2
+
+  Leben, 15, 37, 104
+
+  Leben Raib, 104
+
+  Lecithin, 52
+
+  "Le Ferment" apparatus, 128
+
+  Liebig, 17
+
+  Longevity, 155
+
+
+  M
+
+  Mares' milk, 24
+
+  Matzoon, 15, 38, 106
+
+  Maya, 42;
+    Bulgarian, 10
+
+  Maya Bulgare Company's apparatus, 131
+
+  Meeresy, 5
+
+  Metchnikoff, 34, 40, 44, 121, 158, 163
+
+  Micro-organisms, discovery of, 13
+
+  Middle Ages, 13
+
+  Milk-filling apparatus for bottles, 82
+
+  Milk, general properties of, 57;
+    of different animals, 60;
+    supply of the United Kingdom, 69;
+    industry in the United States, 71;
+    management, 74
+
+  Mitscherlich, 17
+
+  Myristin, 51
+
+
+  N
+
+  Neolithic times, 1
+
+  Nikolaiewa, 95
+
+  Nitrogenous constituents of milk, 52
+
+
+  O
+
+  Ojran, 106
+
+  Olein, 51
+
+  Oxygala of Pliny, 4
+
+
+  P
+
+  Paleolithic times, 1
+
+  Palmitin, 51
+
+  Pasteur, 14, 78
+
+  Pasteurisation, 78
+
+  Pelouze, 17
+
+  Pilaff of rice, 5
+
+  Pina, 21
+
+  Podowyssowski on keffir, 87
+
+  Preparation, of soured milk, 81;
+    in the house, 125;
+    in the dairy, 139
+
+  Primary cooler, 78
+
+  Proteids, 53
+
+  Pyrenees, 4
+
+
+  R
+
+  Reindeer's milk as soured milk, 8
+
+  Rubruquis, William de, 19
+
+
+  S
+
+  _Saccharomyces cerevisseae_, 90
+
+  _Saccharomyces keffir_, 32, 33, 91, 93, 94
+
+  Sakwaska, 88
+
+  Sale of Food and Drugs Act, 1899, 49
+
+  Scheele, 17
+
+  Scholl on keffir, 91
+
+  Scythians, 18
+
+  Secondary cooler, 79
+
+  Shammar Bedouins, 2
+
+  Sheneena, 2
+
+  Skolotowski on keffir, 86
+
+  Smith, Professor Robertson, 3
+
+  Soured milk, in the house, 125;
+    in the dairy, 139;
+    in health and disease, 151;
+    from impure cultures, 158;
+    use of, 159
+
+  Souring of milk, 47, 54
+
+  Specific gravity of milk, 65
+
+  Stearin, 51
+
+  Steriliser, 148
+
+  _Streptobacilli lebeni_, 39
+
+  _Streptobacillus lebenis_, 111
+
+  _Streptococcus a_, 93, 94
+
+  _Streptococcus acidi lactici_, 95, 96
+
+  _Streptococcus b_, 93, 94
+
+  _Streptococcus lacticus_, 92, 93, 122, 124
+
+  Sugar of milk, 54
+
+  Sugar preparations and the soured-milk bacillus, 137
+
+  Suter-Naef on Swiss koumiss, 26
+
+  Swedish whey cheese, 60
+
+  Swiss hard cheese, 113
+
+  Symptoms of disease, 161
+
+
+  T
+
+  Temperature allowances when testing milk, tables of, 66
+
+  Town's dairy equipment, 80
+
+  Transmission of disease by milk, 72
+
+
+  U
+
+  United Kingdom, milk supply of, 69
+
+  United States, milk industry of, 71
+
+  Urgoutnik, 43
+
+
+  V
+
+  Van Leeuwenhoek, 13
+
+  Variation limits of milk, 49
+
+  Vedas, 1
+
+  "Veronelle" apparatus, 132
+
+  Vina, 21
+
+  Vinous fermentation, 17
+
+
+  W
+
+  Willows Refrigerating Company's apparatus, 144, 145
+
+  Wilson on koumiss, 23
+
+
+  Y
+
+  Yoghourt, 9, 42, 46, 107
+
+  Yoghourt bacillus, 109
+
+
+  Z
+
+  Zakvaska, 42
+
+       *       *       *       *       *
+
+  Putnam's
+  Science Series
+
+
+  1. +The Study of Man.+ By A. C. HADDON.
+
+  2. +The Groundwork of Science.+ By ST. GEORGE MIVART.
+
+  3. +Rivers of North America.+ By ISRAEL C. RUSSELL.
+
+  4. +Earth Sculpture, or; The Origin of Land Forms.+ By JAMES GEIKIE.
+
+  5. +Volcanoes; Their Structure and Significance.+ By T. G. BONNEY.
+
+  6. +Bacteria.+ By GEORGE NEWMAN.
+
+  7. +A Book of Whales.+ By F. E. BEDDARD.
+
+  8. +Comparative Physiology of the Brain, etc.+ By JACQUES LOEB.
+
+  9. +The Stars.+ By SIMON NEWCOMB.
+
+  10. +The Basis of Social Relations.+ By DANIEL G. BRINTON.
+
+  11. +Experiments on Animals.+ By STEPHEN PAGET.
+
+  12. +Infection and Immunity.+ By GEORGE M. STERNBERG.
+
+  13. +Fatigue.+ By A. MOSSO.
+
+  14. +Earthquakes.+ By CLARENCE E. DUTTON.
+
+  15. +The Nature of Man.+ By ELIE METCHNIKOFF.
+
+  16. +Nervous and Mental Hygiene in Health and Disease.+ By AUGUST FOREL.
+
+  17. +The Prolongation of Life.+ By ELIE METCHNIKOFF.
+
+  18. +The Solar System.+ By CHARLES LANE POOR.
+
+  19. +Heredity.+ By J. ARTHUR THOMPSON, M.A.
+
+  20. +Climate.+ By ROBERT DECOURCY WARD.
+
+  21. +Age, Growth, and Death.+ By CHARLES S. MINOT.
+
+  22. +The Interpretation of Nature.+ By C. LLOYD MORGAN.
+
+  23. +Mosquito Life.+ By EVELYN GROESBEECK MITCHELL.
+
+  24. +Thinking, Feeling, Doing.+ By E. W. SCRIPTURE.
+
+  25. +The World's Gold.+ By L. DE LAUNAY.
+
+  26. +The Interpretation of Radium.+ By F. SODDY.
+
+  27. +Criminal Man.+ By CESARE LOMBROSO.
+
+  28. +The Origin of Life.+ By H. CHARLTON BASTIAN.
+
+  29. +The Bacillus of Long Life.+ By LOUDON M. DOUGLAS.
+
+  _For list of works in preparation see end of this volume_
+
+       *       *       *       *       *
+
+  _A Selection from the
+  Catalogue of_
+
+  G. P. PUTNAM'S SONS
+
+  Complete Catalogue sent
+  on application
+
+  Putnam's
+  Science Series
+
+
+  +1.--The Study of Man.+ By Professor A. C. HADDON, M.A., D.Sc.,
+       M.R.I.A. Fully illustrated. 8o., net $2.00.
+
+  "A timely and useful volume.... The author wields a pleasing pen and
+  knows how to make the subject attractive.... The work is calculated to
+  spread among its readers an attraction to the science of anthropology.
+  The author's observations are exceedingly genuine and his descriptions
+  are vivid."--_London Athenaeum._
+
+
+  +2.--The Groundwork of Science.+ A Study of Epistemology. By
+       ST. GEORGE MIVART, F.R.S. 8o., net $1.75.
+
+  "The book is cleverly written and is one of the best works of its kind
+  ever put before the public. It will be interesting to all readers, and
+  especially to those interested in the study of science."--_New Haven
+  Leader._
+
+
+  +3.--Rivers of North America.+ A Reading Lesson for Students of Geography
+       and Geology. By ISRAEL C. RUSSELL, Professor of Geology, University
+       of Michigan, author of "Lakes of North America," "Glaciers of North
+       America," "Volcanoes of North America," etc. Fully illustrated.
+       8o., net $2.00.
+
+  "There has not been in the last few years until the present book any
+  authoritative, broad resume on the subject, modified and deepened as
+  it has been by modern research and reflection, which is couched in
+  language suitable for the multitude.... The text is as entertaining as
+  it is instructive."--_Boston Transcript._
+
+
+  +4.--Earth Sculpture; or, The Origin of Land-Forms.+ By JAMES GEIKIE,
+       LL.D., D.C.L., F.R.S., etc., Murchison Professor of Geology
+       and Mineralogy in the University of Edinburgh; author of "The
+       Great Ice Age," etc. Fully illustrated. 8o., net $2.00.
+
+  "This volume is the best popular and yet scientific treatment we know
+  of the origin and development of land-forms, and we immediately
+  adopted it as the best available text-book for a college course in
+  physiography.... The book is full of life and vigor, and shows the
+  sympathetic touch of a man deeply in love with nature."--_Science._
+
+
+  +5.--Volcanoes.+ By T. G. BONNEY, F.R.S., University College, London.
+       Fully illustrated. 8o., net $2.00.
+
+  "It is not only a fine piece of work from a scientific point of view,
+  but it is uncommonly attractive to the general reader, and is likely
+  to have a larger sale than most books of its class."--_Springfield
+  Republican._
+
+
+  +6.--Bacteria+: Especially as they are related to the economy of
+       nature, to   industrial processes, and to the public health.
+       By GEORGE NEWMAN, M.D., F.R.S. (Edin.), D.P.H. (Camb.), etc.,
+       Demonstrator of Bacteriology in King's College, London. With 24
+       micro-photographs of actual organisms and over 70 other
+       illustrations. 8o., net $2.00.
+
+  "Dr. Newman's discussions of bacteria and disease, of immunity, of
+  antitoxins, and of methods of disinfection, are illuminating, and are
+  to be commended to all seeking information on these points. Any
+  discussion of bacteria will seem technical to the uninitiated, but all
+  such will find in this book popular treatment and scientific accuracy
+  happily combined."--_The Dial._
+
+
+  +7.--A Book of Whales.+ By F. E. BEDDARD, M.A., F.R.S. Illustrated
+       8o. $2.00.
+
+  "Mr. Beddard has done well to devote a whole volume to whales. They
+  are worthy of the biographer who has now well grouped and described
+  these creatures. The general reader will not find the volume too
+  technical, nor has the author failed in his attempt to produce a book
+  that shall be acceptable to the zoologist and the naturalist."--_N. Y.
+  Times._
+
+
+  +8.--Comparative Physiology of the Brain and Comparative Psychology.+
+       With special reference to the Invertebrates. By JACQUES
+       LOEB, M.D., Professor of Physiology in the University of Chicago.
+       Illustrated. 8o. $1.75.
+
+  "No student of this most interesting phase of the problems of life can
+  afford to remain in ignorance of the wide range of facts and the
+  suggestive series of interpretations which Professor Loeb has brought
+  together in this volume."--JOSEPH JASTROW, in the _Chicago Dial._
+
+
+  +9.--The Stars.+ By Professor SIMON NEWCOMB, U.S.N., Nautical Almanac
+       Office, and Johns Hopkins University. 8o. Illustrated. Net.
+       $2.00. (By mail, $2.00.)
+
+  "The work is a thoroughly scientific treatise on stars. The name of
+  the author is sufficient guarantee of scholarly and accurate
+  work."--_Scientific American._
+
+
+  +10.--The Basis of Social Relations.+ A Study in Ethnic Psychology. By
+        DANIEL G. BRINTON, A.M., M.D., LL.D., Sc.D., Late Professor of
+        American Archaeology and Linguistics in the University of
+        Pennsylvania; Author of "History of Primitive Religions," "Races
+        and Peoples," "The American Race," etc. Edited by LIVINGSTON
+        FARRAND, Columbia University. 8o. Net, $1.50 (By mail, $1.60.)
+
+  "Professor Brinton has shown in this volume an intimate and
+  appreciative knowledge of all the important anthropological theories.
+  No one seems to have been better acquainted with the very great body
+  of facts represented by these sciences."--_Am. Journal of Sociology._
+
+
+  +11.--Experiments on Animals.+ By STEPHEN PAGET. With an Introduction
+        by Lord Lister. Illustrated. 8o. Net, $2.00. (By mail, $2.20.)
+
+  "To a large class of readers this presentation will be attractive,
+  since it gives to them in a nut-shell the meat of a hundred scientific
+  dissertations in current periodical literature. The volume has the
+  authoritative sanction of Lord Lister."--_Boston Transcript._
+
+
+  +12.--Infection and Immunity.+ With Special Reference to the
+        Prevention of Infectious Diseases. By GEORGE M. STERNBERG,
+        M.D., LL.D., Surgeon-General U. S. Army (Retired). Illustrated.
+        8o. Net, $1.75 (By mail, $1.90.)
+
+  "A distinct public service by an eminent authority. This admirable
+  little work should be a part of the prescribed reading of the head of
+  every institution in which children or youths are gathered.
+  Conspicuously useful."--_N. Y. Times._
+
+
+  +13.--Fatigue.+ By A. MOSSO, Professor of Physiology in the University
+        of Turin. Translated by MARGARET DRUMMOND, M.A., and W. B.
+        DRUMMOND, M.B., C.M., F.R.C.P.E., extra Physician, Royal
+        Hospital for Sick Children, Edinburgh; Author of "The Child.
+        His Nature and Nurture." Illustrated. 8o. Net, $1.50.
+
+  "A book for the student and for the instructor, full of interest, also
+  for the intelligent general reader. The subject constitutes one of the
+  most fascinating chapters in the history of medical science and of
+  philosophical research."--_Yorkshire Post._
+
+
+  +14.--Earthquakes.+ In the Light of the New Seismology By CLARENCE
+        E. DUTTON, Major, U. S. A. Illustrated 8o. Net, $2.00. (By
+        mail, $2.20.)
+
+  "The book summarizes the results of the men who have accomplished the
+  great things in their pursuit of seismological knowledge. It is
+  abundantly illustrated and it fills a place unique in the literature
+  of modern science"--_Chicago Tribune._
+
+
+  +15.--The Nature of Man.+ Studies in Optimistic Philosophy. By ELIE
+  METCHNIKOFF, Professor at the Pasteur Institute. Translation and
+  introduction by P. CHAMBERS MITCHELL, M.A., D.Sc. Oxon. Illustrated.
+  8o. Net, $1.50.
+
+  "A book to be set side by side with Huxley's Essays, whose spirit it
+  carries a step further on the long road towards its goal"--_Mail and
+  Express._
+
+
+  +16.--The Hygiene of Nerves and Mind in Health and Disease.+ By
+        AUGUST FOREL, M.D., formerly Professor of Psychiatry in the
+        University of Zurich. Authorized Translation. 8o. Net, $2.00.
+       (By mail, $2.20.)
+
+  A comprehensive and concise summary of the results of science in its
+  chosen field. Its authorship is a guarantee that the statements made
+  are authoritative as far as the statement of an individual can be so
+  regarded.
+
+
+  +17.--The Prolongation of Life.+ Optimistic Essays. By ELIE
+        METCHNIKOFF, Sub-Director of the Pasteur Institute. Author of
+        "The Nature of Man." etc. 8o., Illustrated Net, $2.50.
+        (By mail, $2.70.) Popular Edition. With an introduction by
+        Prof. CHARLES S. MINOT. Net, $1.75.
+
+  In his new work Professor Metchnikoff expounds at greater length, in
+  the light of additional knowledge gained in the last few years, his
+  main thesis that human life is not only unnaturally short but
+  unnaturally burdened with physical and mental disabilities. He
+  analyzes the causes of these disharmonies and explains his reasons for
+  hoping that they may be counteracted by a rational hygiene.
+
+
+  +18.--The Solar System.+ A Study of Recent Observations. By Prof.
+        CHARLES LANE POOR, Professor of Astronomy in Columbia
+        University. 8o. Illustrated. Net, $2.00.
+
+  The subject is presented in untechnical language and without the use
+  of mathematics. Professor Poor shows by what steps the precise
+  knowledge of to day has been reached and explains the marvellous
+  results of modern methods and modern observations.
+
+
+  +19.--Climate--Considered Especially in Relation to Man.+ By ROBERT
+        DECOURCY WARD, Assistant Professor of Climatology in Harvard
+        University. 8o. Illustrated. Net, $2.00.
+
+  This volume is intended for persons who have not had special training
+  in the technicalities of climatology. Climate covers a wholly
+  different field from that included in the meteorological text-books It
+  handles broad questions of climate in a way which has not been
+  attempted in a single volume The needs of the teacher and student have
+  been kept constantly in mind.
+
+
+  +20.--Heredity.+ By J. ARTHUR THOMSON, M.A., Professor of Natural
+        History in the University of Aberdeen; Author of "The Science of
+        Life," etc. 8o. Illustrated. Net, $3.50.
+
+  The aim of this work is to expound, in a simple manner, the facts of
+  heredity and inheritance as at present known, the general conclusions
+  which have been securely established, and the more important theories
+  which have been formulated.
+
+
+  +21.--Age, Growth, and Death.+ By CHARLES S. MINOT, James Stillman
+        Professor of Comparative Anatomy in Harvard University,
+        President of the Boston Society of Natural History, and Author
+        of "Human Embryology," "A Laboratory Text-book of Embryology,"
+        etc. 8o. Illustrated.
+
+  This volume deals with some of the fundamental problems of biology,
+  and presents series of views (the results of nearly thirty years of
+  study), which the author has correlated for the first time in
+  systematic form.
+
+
+  +22.--The Interpretation of Nature.+ By C. LLOYD MORGAN, LL.D.,
+        F.R.S. Crown 8vo. Net, $1.25.
+
+  Dr Morgan seeks to prove that a belief in purpose as the causal
+  reality of which nature is an expression is not inconsistent with a
+  full and whole-hearted acceptance of the explanations of naturalism.
+
+
+  +23.--Mosquito Life.+ The Habits and Life Cycles of the Known
+        Mosquitoes   of the United States; Methods for their Control;
+        and Keys for Easy Identification of the Species in their Various
+        Stages. An account based on the investigation of the late James
+        William Dupree, Surgeon-General of Louisiana, and upon the
+        original observations by the Writer. By EVELYN GROESBEECK
+        MITCHELL, A.B., M.S. With 64 Illustrations. Crown 8vo.
+        Net, $2.00.
+
+  This volume has been designed to meet the demand of the constantly
+  increasing number of students for a work presenting in compact form
+  the essential facts so far made known by scientific investigation in
+  regard to the different phases of this, as is now conceded, important
+  and highly interesting subject. While aiming to keep within reasonable
+  bounds, that it may be used for work in the field and in the
+  laboratory, no portion of the work has been slighted, or fundamental
+  information omitted, in the endeavor to carry this plan into effect.
+
+
+  +24.--Thinking, Feeling, Doing.+ An Introduction to Mental Science.
+        By E. W. SCRIPTURE, Ph.D., M.D., Assistant Neurologist Columbia
+        University, formerly Director of the Psychological Laboratory at
+        Yale University. 189 Illustrations. 2d Edition, Revised and
+        Enlarged. Crown 8vo. Net, $1.75.
+
+  "The chapters on Time and Action, Reaction Time, Thinking Time,
+  Rhythmic Action, and Power and Will are most interesting. This book
+  should be carefully read by every one who desires to be familiar with
+  the advances made in the study of the mind, which advances, in the
+  last twenty-five years, have been quite as striking and epoch-making
+  as the strides made in the more material lines of knowledge."--_Jour.
+  Amer. Med. Ass'n._, Feb. 22, 1908.
+
+
+  +25.--The World's Gold.+ By L. DE LAUNAY, Professor at the Ecole
+        Superieure des Mines. Translated by Orlando Cyprian Williams.
+        With an Introduction by Charles A. Conant, author of "History of
+        Modern Banks of Issue," etc. Crown 8vo. Net, $1.75.
+
+  M. de Launay is a professor of considerable repute not only in France,
+  but among scientists throughout the world. In this work he traces the
+  various uses and phases of gold; first, its geology; secondly, its
+  extraction; thirdly, its economic value.
+
+
+  +26.--The Interpretation of Radium.+ By FREDERICK SODDY, Lecturer
+        in Physical Chemistry in the University of Glasgow. Crown 8vo.
+        With Diagrams. Net, $1.75.
+
+  As the application of the present day interpretation of Radium (that
+  it is an element undergoing spontaneous disintegration) is not
+  confined to the physical sciences, but has a wide and general bearing
+  upon our whole outlook on Nature, Mr. Soddy has presented the subject
+  in non-technical language, so that the ideas involved are within reach
+  of the lay reader. No effort has been spared to get to the root of the
+  matter and to secure accuracy, so that the book should prove
+  serviceable to other fields of science and investigation, as well as
+  to the general public.
+
+
+  +27.--Criminal Man.+ According to the Classification of CESARE
+        LOMBROSO. Briefly Summarized by his Daughter, Gina Lombroso
+        Ferrero. With 36 Illustrations and a Bibliography of Lombroso's
+        Publications on the Subject. Crown 8vo. Net, $2.00.
+
+  Signora Guglielmo Ferrero's resume of her father's work on criminal
+  anthropology is specially dedicated to all those whose office it is to
+  correct, reform, and punish the criminal, with a view to diminishing
+  the injury caused to society by his anti-social acts; also to
+  superintendents, teachers, and those engaged in rescuing orphans and
+  children of vicious habits, as a guide in checking the development of
+  evil germs and eliminating incorrigible subjects whose example is a
+  source of corruption to others.
+
+       *       *       *       *       *
+
+  The most valuable production since Darwin's "Origin of Species."
+
+  The Nature of Man
+
+  _Studies in Optimistic Philosophy_
+
+  By Elie Metchnikoff
+
+  Sub-Director of the Pasteur Institute, Paris
+
+  Translated with an Introduction by
+
+  P. Chambers Mitchell
+
+  Secretary of the Zoological Society
+
+  Octavo. Illustrated. Popular Edition. $1.50 net. By mail, $1.65
+
+  It is not often that a scientific book may be read with ease, profit,
+  and pleasure by the general reader, so that M. Metchnikoff's book
+  comes in the nature of an agreeable surprise. It is marked by a
+  refreshing _naivete_ and a large simplicity which are
+  characteristically Russian. The scientific importance of this work is
+  so great that it is spoken of in England as the most valuable
+  production since Darwin's _Origin of Species_.
+
+  Opinions of the Press
+
+  "An extremely interesting and typical book.... With a distinguished
+  frankness, M. Metchnikoff defines his attitude to our universal
+  prepossessions. It is his theory that the infirmities of age are to be
+  overcome. If there be ground for this conception, humanity is to be
+  profoundly changed and what we call life now, will be the childhood
+  and youth of that longer and larger life."--H. G. WELLS, in _London
+  Speaker_.
+
+  "Undoubtedly a great book (in some quarters it has been hailed as the
+  greatest since Darwin's famous message to the world) and should be
+  read by all intelligent men and women."--_The Nation._
+
+  "A book to be set side by side with Huxley's Essays, whose spirit it
+  carries a step further on the long road towards its goal."--_Mail and
+  Express._
+
+  New York--G. P. Putnam's Sons--London
+
+       *       *       *       *       *
+
+  "_Remarkable for its simple language and clear
+  style.... Bears the stamp of a production of
+  an erudite scientist and a deep thinker._"--Science.
+
+
+  The Prolongation of Life
+
+  Optimistic Essays
+
+  _By_ Elie Metchnikoff
+
+  _Author of "The Nature of Man," etc._
+
+  _8vo. Illustrated Popular Edition. $1.75 net By mail, $1.90_
+
+  M. Elie Metchnikoff is one of those rare scientists who have found a
+  way to lay hold of and present to the world in untechnical
+  phraseology, intelligible to the lay mind, such results of his
+  researches as are of universal interest and go straight home to the
+  bosoms and business of intelligent men. _The Nature of Man_, by the
+  same author, was one of the most fascinating books, at once popular,
+  and scientific, which have appeared for decades. The book here in
+  question will stand beside it as a worthy companion volume. It is
+  satisfactory to report that, absorbed as Metchnikoff is in "material"
+  problems, and deep as he is in the mysteries of the physical universe,
+  these essays show him to be an optimist who speaks with no uncertain
+  voice.
+
+  A great deal of attention is given in _The Prolongation of Human Life_
+  to the subject of old age and its causes, with scientific observations
+  of special cases among human beings and the lower animals. The author
+  suggests means of prolonging life and health, while contemplating
+  natural death with serenity, and finding that agreeable sensations
+  accompany its approach. Beyond a certain point it seems to him a
+  disadvantage to prolong life. Passing on from these mortuary
+  lucubrations, the essays concern themselves with psychological
+  matters, with optimism and pessimism and in general with questions of
+  science and morals. The temperaments of certain great men are analyzed
+  in studies that have for their subjects respectively Byron, Leopardi,
+  Schopenhauer, and Goethe. In the preface the author says that he has
+  avoided, as far as possible, repeating points which have been
+  sufficiently treated in _The Nature of Man_.
+
+
+  G. P. PUTNAM'S SONS
+
+  NEW YORK     LONDON
+
+
+
+
+
+End of Project Gutenberg's The Bacillus of Long Life, by Loudon Douglas
+
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