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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..d7b82bc --- /dev/null +++ b/.gitattributes @@ -0,0 +1,4 @@ +*.txt text eol=lf +*.htm text eol=lf +*.html text eol=lf +*.md text eol=lf diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..a4bfb3e --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #55930 (https://www.gutenberg.org/ebooks/55930) diff --git a/old/55930-0.txt b/old/55930-0.txt deleted file mode 100644 index 0126b1f..0000000 --- a/old/55930-0.txt +++ /dev/null @@ -1,3743 +0,0 @@ -Project Gutenberg's Section-Cutting: A Practical Guide, by Sylvester Marsh - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world 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. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: Section-Cutting: A Practical Guide - To the preparation and mounting of sections for the microscope, etc. - -Author: Sylvester Marsh - -Release Date: November 10, 2017 [EBook #55930] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK SECTION-CUTTING: A PRACTICAL GUIDE *** - - - - -Produced by Chris Curnow, Barry Abrahamsen, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - - - - - - SECTION-CUTTING: - - A PRACTICAL GUIDE - - TO THE - - PREPARATION AND MOUNTING OF SECTIONS FOR - THE MICROSCOPE, - - _SPECIAL PROMINENCE BEING GIVEN TO THE - SUBJECT OF ANIMAL SECTIONS._ - - - - BY - - - DR. SYLVESTER MARSH. - - - _WITH ILLUSTRATIONS._ - - - REPRINTED FROM THE LONDON EDITION, WITH NOTES AND AN APPENDIX - ON THE SELECTION AND CARE OF SECTION KNIVES. - - - - NEW YORK: - INDUSTRIAL PUBLICATION COMPANY. - 1879. - - - - ------------------------------------------------------------------------- - - - - - PREFACE. - -If we glance at any of the numerous magazines devoted either wholly or -in part to the subject of microscopy, we shall hardly fail to be struck -with the numerous queries relating to SECTION-CUTTING, which are to be -found in its pages. A simple explanation of this wide-spread want is -afforded by the fact that the use of the microscope has at the present -day extended to (and is still rapidly spreading amongst) vast numbers of -students, who, in many instances, possess neither the leisure nor the -means to refer for information to large and expensive text-books. -Moreover, were they actually to consult such works, they would -practically fail to obtain the information of which they are in need, -for the coveted instruction is to be found in those treatises only in a -scattered and fragmentary form—no work with which we are acquainted -treating of the subject in anything like a detailed manner. To fill this -_vacuum_ in the literature of microscopy the present manualette has been -prepared. Little claim is made to originality, yet the book is by no -means a mere compilation, but the outcome of long and extensive personal -experience in the cutting and mounting of microscopical sections. Every -process described has been put to the test of actual trial, so that its -worth may confidently be depended upon. Many of the little points -insisted upon in the ensuing pages will doubtless to the practised -microscopist appear superfluous or even puerile; but a vivid -recollection of our own early failures and disappointments assures us -that it is just these very _minutiæ_ of detail which will be found most -serviceable in directing and sustaining the faltering footsteps of the -tyro. - - ST. HELENS, _September, 1878_. - - - - ------------------------------------------------------------------------- - - - - - PREFACE TO AMERICAN EDITION. - - -------------- - - -Dr. Marsh’s book cannot fail to promote the practical study of histology -wherever the English language is spoken, and under ordinary -circumstances the students of this country might have been left to the -use of the London edition. But a careful reading showed that one or two -points which are perfectly clear to British readers might be a source of -doubt and difficulty to students on this side. At the present day in -this country histology is a favorite study with very many private -students who have no access to teachers or large libraries, and for the -purpose of smoothing their path we have added such information as was -obviously desirable. In the hope that these additions will prove of -value, we submit the book to American readers. - - NEW YORK, _January, 1879_. - - - - ------------------------------------------------------------------------- - - - - - CONTENTS. - - ------- - - - PART I. - - - Introduction 11 - On Cutting Unprepared Vegetable Tissues 12 - On Cutting Unprepared Animal Tissues 13 - Preparation of Vegetable Tissues 15 - Preparation of Animal Tissues 16 - Special Methods of Hardening 19 - Cutting Hardened Tissues by Hand 19 - Microtome 20 - Æther Microtome 24 - Section-Knife 24 - Imbedding in Paraffine for Microtome 26 - Employment of Microtome 29 - Staining Agents 31 - Carmine Staining 32 - Mounting Media 36 - Mounting in Glycerine 38 - Uses of Freezing Microtome 42 - Employment of Freezing Microtome 43 - Logwood Staining 47 - Absolute Alcohol 50 - Clove Oil 51 - Canada Balsam 51 - Mounting in Balsam 53 - Finishing the Slide 55 - - - PART II. - - Special Methods 57 - Bone 57 - Brain 59 - Cartilage 60 - Coffee Berry 62 - Fat 63 - Hair 63 - Horn, etc. 64 - Intestine 64 - Liver 65 - Lung 65 - Muscle 66 - Orange-peel 67 - Ovary 67 - Porcupine Quill 67 - Potato 67 - Rush 68 - Skin 68 - Spinal Cord 69 - Sponge 71 - Stomach 71 - Tongue 71 - Vegetable Ivory 72 - Wood 72 - Note A, 75 - Note B, 75 - Note C, 76 - Note D, 76 - Note E, 76 - Note F, 77 - Note G, 77 - Note H, 93 - Note I, 94 - Index - - - - ------------------------------------------------------------------------- - - - - - SECTION-CUTTING. - - -------------- - - PART I. - -1. _Introduction._—Many of the most interesting objects with which the -microscopist has to deal, cannot be made to reveal their beauty or -minute structure until they have been cut into slices or _sections_, of -such a degree of thinness as to render them transparent, and thus permit -of their examination by transmitted light, with objectives of varying -power. Unfortunately, however, very few of the objects of this class -are, in their natural condition, in a suitable state to be submitted to -this method of procedure. Some are of such a soft and yielding nature -that any attempt to cut them is an utter failure, for in place of a -perfect section being obtained, nothing remains upon the knife but a -mass of diffluent pulp; others, again, are of such density as to resist -the action of any cutting instrument. - -It is evident, therefore, that nothing can be done with such refractory -materials until, by subjection to appropriate methods of preparation, -they shall have been reduced to such a consistence as to render them -suitable for cutting. How this is to be accomplished will depend -entirely upon the physical and chemical nature of the substance to be -operated upon. As the various objects differ so widely from each other -in these respects, so must the methods of preparation suitable to each -also vary. It is clear, therefore, that no general directions for -attaining this end can be given which would be of any practical value. -It is possible, however, and very convenient, to arrange the various -objects into groups or classes, to the treatment of each of which -certain general rules are applicable; but there will still remain a -comparatively numerous series of objects whose individual peculiarities -of structure will demand for them correspondingly special methods of -preparation. When such objects come to be spoken of, the particular -treatment most suitable to each will also be noticed. - -2. _On Cutting unprepared Vegetable Tissues._—There are some few -substances, however, which may with more or less success be cut into -sections whilst in their natural condition. Such objects are to be found -in the vegetable world in certain kinds of leaves and allied structures, -whilst in the animal kingdom they are principally represented by the -various internal organs of man and the lower animals. Special directions -are given in text-books for the preparation of sections of leaves and -similar substances. For instance, it is recommended to lay the leaf, -etc., on a piece of fine cork, and with a sharp knife to shave off thin -slices, cutting down upon the cork. Another plan is to place the leaf, -etc., between two thin layers of cork, and cut through the mass. No -method, however, is at once so simple and successful as the process of -imbedding in paraffine. To do this, it is necessary to make a paper -mould by twisting a strip of stout writing paper round a ruler, and -turning-in the paper over the end of the ruler. This mould, the height -of which may vary from an inch to an inch and a half, should now be -about half filled with melted paraffine mixture (§ 11), the leaf or -other object plunged into it, and held in position by small forceps till -the paraffine has become sufficiently solidified to yield it a support. -More of the paraffine mixture is now poured in until the specimen is -thoroughly imbedded; the whole is to be put away in a cold place for an -hour or so, when the mass will be found sufficiently firm to be cut with -ease. Sections may be made with a razor kept constantly wetted with -water, or, if the preservation of colour be no object, methylated spirit -may be employed for the purpose. As the subsequent treatment of such -sections in no wise differs from that required by those cut in the -microtome, we shall defer its consideration until that method of section -has been described (§ 12). - -3. _On Cutting unprepared Animal Tissues._—For the cutting of fresh -_animal_ tissues several plans may be followed. Thus, if a section of -only very limited area be required, it may be obtained by snipping a -piece off the tissue with a pair of bent scissors, which, for this -purpose, are so made that the blades are _curved on the flat_ -(Carpenter). If this be carefully performed it will be found that a -large portion of the section (particularly at the circumference) so -obtained will be sufficiently thin for examination. If a larger section -be desired, an attempt may be made to cut it with a very sharp scalpel -or razor, the blade of which whilst in use must be kept _flooded_ with -water, or spirit, the latter of which is to be preferred. Recourse may -also be had to _Valentin’s_ knife. This consists of two long, narrow -blades, running parallel to each other, the distance at which the blades -are held apart, and which, of course, determines the thickness of the -section, being regulated by means of a fine screw passing through both -blades. A milled head attached to this screw gives a ready means of -opening or closing the blades, so as to bring them to the desired degree -of approximation. The method of using the knife is very simple. After -having “set” the blades at the desired distance apart by means of the -milled head, the tissue to be cut is held in the left hand immersed in a -basin of water. The knife is now steadily and with a rapid motion -_drawn_ through the tissue, care being taken that the cut is made in -such a manner that the blades move from heel to point. By slightly -separating the blades and gently shaking them in the water, the section -at once becomes disengaged. After use, the blades must be thoroughly -dried, when they may be smeared with some oil which does not readily -oxidize. For this purpose, a very suitable oil is that known as -“Rangoon.”[1] Though it has been deemed advisable briefly to describe -the preceding methods of cutting unhardened tissues, it will be found -that for the purposes of the ordinary microscopical student sections so -obtained are of very little value. They are always of very limited -dimensions, seldom of uniform thickness, and often so extremely friable -as to render it very difficult and frequently impossible to submit them -with safety to such further treatment as is necessary to fit them for -being mounted as permanent objects. This method of section-cutting, -however, is not without its uses, for by its means the medical -practitioner is provided with a simple and ready method of roughly -investigating the structure of morbid tissues, whilst to the general -student it furnishes an easy means of making a cursory examination of -certain substances, in order that he may determine whether it be worth -his while to subject them to some of those various processes of -hardening hereafter to be described. - -Footnote 1: - - Note A. - -4. _Preparation of Vegetable Tissues._—Let us now pass to a brief -consideration of the methods usually adopted for preparing the various -objects for easy section. In the case of _vegetable_ tissues, not only -do we, as a rule, find their texture of too great density to be readily -cut in their natural condition, but they also contain much resinous and -starchy matter, of which it is highly desirable to get rid. In order to -do this we first cut the substance (say a stem or root) into small -pieces, which are to be placed in water for three or four days, by which -time all the soluble gummy matters will have disappeared. The pieces are -now transferred to a wide-necked bottle, containing methylated -spirit,[2] which, in the course of a few days, will dissolve out all the -resin, etc. Many kinds of woody tissue are by these processes reduced to -a fit condition for immediate cutting; others, however, are so hard as -to render it necessary to give them another soaking for some hours in -water, to bring them to a sufficient degree of softness to cut easily. -If the wood (as in some few refractory cases will happen) be still too -hard for section, a short immersion in warm, or if necessary, in boiling -water, will not fail effectually to soften it. The treatment of such -members of the vegetable division as require peculiar methods, will be -found described in future pages. - -Footnote 2: - - Note B. - -5. _Preparation of Animal Tissues._—_Animal_ tissues differ from one -another so greatly, both in consistence and in chemical composition, as -well as in their degree of natural hardness, that no general rules can -be given which would be applicable to the preparation of the whole -class. Such as are of any considerable degree of hardness, as horn and -kindred structures, must be treated much in the same manner as the -denser varieties of wood, viz., by more or less prolonged immersion in -water—cold, hot, or boiling. Those which are of extreme hardness, as -bones and teeth, can be cut only by following certain special methods, -full details of which will be found in the Second Part of this work (§ -26). Many, and indeed the vast majority of animal tissues, offer a -direct contrast in point of hardness to those we have just been -considering. All the internal organs of the body are, when freshly -removed, of much too soft a nature to permit, when in their unprepared -condition, of easy or perfect cutting. It is upon bringing them to that -critical degree of hardness, which is often so difficult to attain, that -the chief secret of successful section-cutting depends; for unless the -hardening process has been carried up to, but not beyond, a given point, -which varies with different tissues, the operator, however dexterous, -will fail to obtain satisfactory sections. For, if the hardening has -fallen short of this critical point, he is, to some extent, in the same -position as if he were dealing with unhardened tissues; whilst, if this -point has been exceeded, the tissue will have become so brittle as to -crumble before the knife. For the purpose of hardening animal tissues, -the student has at his command two principal agents, namely, alcohol and -chromic acid, each of which possesses advantages of its own, but the use -of each of which is also attended by its own inconveniences. Thus, by -the use of alcohol, there is very much less risk of overhardening the -specimen than if chromic acid had been employed. Alcohol, however, -though a capital indurating agent in some instances, does not answer so -well in many others. Chromic acid is, therefore, to be preferred for -general use. It is, however, a very delicate agent to manage, for unless -the greatest care be taken it is exceedingly likely to overharden -tissues submitted to its action, and when this happens the specimen -becomes utterly useless for cutting, as there is no known means of -removing the extreme brittleness which it has acquired. By taking the -precautions now to be given, this overhardening may generally be -avoided. Let us harden a portion of some viscus, say the kidney, for -instance. Suppose we cut from the organ five or six small pieces (from -half to three-quarters of an inch square, _not larger_). These must be -placed in a mixture of equal parts of methylated spirit and water for -three days, at the end of which period they may be transferred to a -solution of chromic acid, made by dissolving twenty grains of the pure -acid in sixteen ounces of distilled water. The solution should be kept -in a wide-necked bottle furnished with a glass stopper. At the -expiration of seven days, pour off the solution and replace it by fresh. -At the end of another week, carefully examine the immersed tissues, and -by means of a sharp razor see if they have acquired the necessary degree -of hardness to allow of a section of _moderate_ thinness being made. If -so, remove the pieces and put them into a stoppered bottle containing -from six to eight ounces of methylated spirit. If, however, the -hardening be found not to be sufficiently advanced, the chromic acid -solution is to be poured off and again replaced by fresh. It will now be -necessary to examine the tissues at intervals of about two days, until -they are found to be sufficiently hard, when they must be transferred to -the spirit. Under no circumstances, however, should they be permitted to -remain in the chromic acid longer than the end of the third week, and -though they should at this time appear not to have undergone sufficient -induration, yet it will be advisable to transfer them to the methylated -spirit, which in a short time will _safely_ complete the process of -hardening, without any risk being run of the tissue becoming ruinously -brittle. It will be noticed, that when the specimens have been -transferred to spirit, the latter will in a day or two become of a deep -yellow color, whilst a thick flocculent deposit falls to the bottom of -the bottle. The tissues should then be removed, the bottle emptied and -well washed, and, being refilled with clean spirit, the preparations are -again to be replaced. This may occasionally be repeated, until the -spirit becomes and remains perfectly bright and clear. The specimens are -then ready for section. - -6. _Special Methods of Hardening._—The brain (§ 27), spinal cord (§ 43), -liver (§ 34), and several other organs, etc., require special methods of -hardening, details of which will be found in the paragraph devoted to -each. In the case of _injected_ preparations, the best plan is to harden -them in alcohol from the outset, beginning with weak spirit, and -gradually increasing the strength as the hardening proceeds. When the -object has been injected with Prussian blue, a few drops of hydrochloric -acid should be added to the alcohol to fix the color. - -It may here be observed, that specimens of _morbid tissues_ require, as -a general rule, a shorter immersion in chromic acid solution than -healthy tissues do. A very small degree of overhardening speedily -renders them brittle and useless. They should, therefore, be removed -from the acid medium at the end of ten days or a fortnight, and their -further hardening carried on by means of alcohol. - -7. _Cutting Hardened Tissues by Hand._—Our material being now reduced to -a fit condition for cutting, let us proceed to consider the several -methods by which this may be effected. The readiest and most simple -plan, if the piece be large enough, is to hold it in the left hand, and, -having brought the surface to a perfect level by cutting off several -rather thick slices, endeavor to cut a thin section by the aid of a very -sharp razor, the blade of which must be kept well _flooded_ with spirit. -As in the use of _Valentin’s_ knife, so here, great care must be taken -steadily to _draw_ the blade across the tissue, every effort being made -to avoid _pushing_ the knife, else the section will be _torn off_, -instead of being _cut_. Though this method[3] is of very great -importance for many purposes, yet a considerable degree of manipulative -skill is required to enable the operator to obtain anything like perfect -sections by its means, and, unfortunately, this skill is acquired by -very few persons indeed, even after much practice. If the piece which it -is desired to cut be too small to be conveniently held in the hand, it -may be imbedded in paraffine in the manner already described (§ 3). A -very simple imbedding agent, and one of the greatest practical value, is -a strong solution of gum arabic, which, upon being dehydrated either by -ordinary drying or the action of alcohol, soon acquires such a degree of -hardness as to permit it (with the imbedded tissue) to be cut with ease. -As this method of imbedding, however, is most frequently resorted to -where, by its means, special difficulties have to be overcome, a full -description of the process (§ 35) will be deferred until such special -cases come to be spoken of. - -Footnote 3: - - Note C. - -8. _Microtome._—Although the preceding plans may be sufficient to answer -all his requirements, if the student wishes to obtain only one or two -sections of small dimensions, of a given object, if he requires a number -of such sections he will find these methods fail him, for even though by -practice he may have attained to considerable aptitude in the use of the -knife, it will still unquestionably happen that the vast majority of his -sections will be more or less imperfect. If, therefore, it be desired to -procure a number of perfect sections, of equable thickness and large -area, it is absolutely necessary to resort to the use of some form or -other of microtome, or section-cutter. This instrument, in its simplest -form, merely consists of a stout brass tube closed at one end, and being -by the other fixed at right angles into a smooth plate of metal. A plug -or disk of brass, accurately fitting the interior of the tube, is acted -upon by a fine threaded screw piercing the base of the tube, and by -means of which the plug, and any object it may support, can be elevated -at pleasure. The object by this means being made gradually to rise out -of the tube, sections are cut from it by simply gliding a sharp knife -along the smooth cutting-plate, and hence across the specimen. Any -intelligent worker in brass would make an instrument of this kind at a -very small cost, and although perhaps it might lack the finish of an -instrument bought at the optician’s, it would, if accurately made, do -its work as well as the most complicated and expensive. If, however, the -student resolves to purchase a microtome, there are a variety of forms -in the market from which he may choose. A few hints may perhaps be of -service in enabling him to make a judicious selection. At the outset we -may say that unless the student intends to devote himself solely to the -production of sections of wood, etc., he ought not to procure one of -those forms of microtome known as wood section-cutters, in which the -object to be cut is held in position in the tube by means of a binding -screw which pierces its side.[4] Although these machines are all that -can be desired for cutting hard bodies, they are not so suitable for -soft ones. The chief points to be attended to in selecting a microtome -are, (1) that the cutting-plate of the instrument be made of glass, or -in default of this, of very hard metal of the most perfect -smoothness;[5] (2) that the diameter of the tube be neither too large -nor too small—it ought not to be less than 5/8-in., or greater than 1 -inch;[6] (3) that the screw, which should be _fine_ and well cut, be -provided with a graduated head; (4) that there be some kind of index by -which fractional portions of a revolution of the screw may be measured; -and (5) that the plug fit the tube of the microtome so accurately that -when melted paraffine, gum, or other imbedding agent be poured into it, -it may not find its way between the plug and side of the tube (§ 18). It -often happens in cutting tissues imbedded in paraffine, that the -pressure of the knife causes the cylinder of the imbedding agent to -twist round in the tube of the machine, and so cause considerable -difficulty and annoyance. This evil is usually met by running a deep -groove across the upper surface of the plug, and into this the paraffine -sinks, and so is prevented from rotating. It will be found, moreover, -that another difficulty of a kindred, though much more serious -character, will frequently be encountered. During section the paraffine -has a tendency not only to rotate, but also to become loosened from the -subjacent plug, and to _rise_ in the tube of the microtome. When this -happens the power to cut sections of uniform thickness has completely -gone, for some will now be found to be many times thicker than others; -in fact, the irregularity in this respect soon becomes so monstrous as -to render it useless to prolong the sitting. In the ordinary run of -microtomes no provision seems to have been made to meet this difficulty, -and for this reason many instruments, of otherwise great merit, have -their efficiency seriously impaired. Fortunately, this imperfection is -easily remedied, all that is required being that the upper surface of -the plug should be furnished with some kind of projection, having at its -summit a table-like expansion, as shown at A in the figure. The -imbedding paraffine, by penetrating beneath and around this, becomes -firmly attached to the plug, and thus all risk of its rising is -effectually avoided. If the student wishes to secure a really -first-class instrument, none can be so confidently recommended as the -freezing microtome of Professor Rutherford. In addition to its being the -best instrument for carrying out the freezing method (§ 18), this -machine is equally effective for cutting tissues imbedded in paraffine, -or any of the other agents used for that purpose; indeed, whatever work -a microtome _can_ do, _this one_ will perform. - -Footnote 4: - - Note D. - -Footnote 5: - - Note E. - -Footnote 6: - - Note F. - - - [Illustration: SECTION OF MICROTOME-TUBE SHOWING ARRANGEMENT (A) TO - PREVENT “RISE” OF PARAFFINE.] - - -9. _Æther Microtome._—A word here as to freezing microtomes, where the -agent used is æther. Such as have fallen under our notice have not -answered the expectations we were justly entitled to form of them. That -it is possible to freeze a piece of tissue by their use is undeniable, -but it is, as a rule, at an expenditure of such a quantity of æther -(only the very best of which must be used) as to constitute it a very -expensive proceeding. Another serious disadvantage they possess is, that -if the supply of æther be intermitted for only a very short time, the -already frozen tissue thaws with great and most inconvenient rapidity. - -10. _Section-Knife._—Of not less importance than the microtome is the -section-knife, to be used in conjunction with it. How perfect soever the -former, and whatever the dexterity of the operator, unless he be -provided with a suitable and well-made knife, he will never succeed in -obtaining satisfactory results. As to the most desirable _size_ of the -knife, much difference of opinion seems to exist, section knives varying -in this respect from a blade of extreme shortness to one which fell -under our observation, in which the portentous length of _thirteen_ -inches was attained. What advantages were to be expected by prolonging -the blade to this extravagant length, must remain an inscrutable mystery -to all save its designer. Concerning the _shape_ of the knife, it is -frequently advised that the surface which has to glide along the -cutting-plate of the microtome should be ground _flat_. A most -unsuitable arrangement, as a very little actual experience of -section-cutting will speedily demonstrate. After many unsuccessful -attempts to obtain a really good and reliable section-knife, we -determined to have one specially made, which, as it has proved -everything that could be desired, merits a brief description. It is of -the utmost importance that the blade be made of good and well-tempered -steel, not only that it may be capable of receiving an edge of the most -exquisite keenness, but also that it may _retain it_. The knife of which -we speak (and which was made by Mr. Gardner, of South Bridge, Edinburgh) -is furnished with a blade _four inches_ long, and 7/8-inch broad, set -into a square handle of boxwood, also four inches in length. The -thickness of the blade at the back is not quite 1/4-inch, while _both_ -of its surfaces are slightly hollow ground. It is essentially necessary -that the back and edge of the blade be strictly parallel to each other, -otherwise the knife, when in use, will have such a tendency to tilt over -as to render its management extremely difficult. It is very easy to -discover if this condition be fulfilled, for if on carefully laying the -flat of the blade upon a piece of level glass, every portion of both -back and edge are found to be in close contact with it, the knife may in -this respect be considered perfect. Every student who aspires to be a -successful section-cutter should provide himself with a good Turkey -oilstone, _and learn to use it_. He should also possess a razor strop, -as it will be in constant requisition.[7] It may here be remarked that -though _razors_, as a rule, are unsuitable for use with the microtome -from want of uniformity in the thickness of their blades, yet, if only a -small object is to be cut—for instance, a thin root or stem—very good -results may be obtained from their use, especially if one of the -old-fashioned make, having a thick back and slightly _concave_ surfaces, -be employed. - -11. _Imbedding in Paraffine for Microtome._—Having described at some -length the various instruments necessary for section-cutting, we will -now consider how they are to be used. Let us endeavor to cut some -sections—say of a piece of kidney—and in so doing we will adopt the -“paraffine” method of imbedding. Ordinary paraffine, however, when used -alone, is rather too hard for our purpose. In order, therefore, to bring -it to a suitable consistence, it must be mixed with one-fifth its weight -of common unsalted lard, a gentle heat applied, and the two thoroughly -stirred together. A quantity of this should be prepared, so that it may -always be ready when wanted—it is very conveniently kept in an ointment -pot or preserve jar, the top of the latter being well covered, to keep -out the dust. When it is intended to use this mixture for the purpose of -imbedding, only just about the quantity required should be melted; for -in doing this it is advisable to use as low a degree of heat as -possible, not only to prevent injury to the tissue to be imbedded, but -also that the paraffine when cooling may not undergo such an amount of -contraction as to cause it to shrink from the sides of the -microtome-tube. It is therefore a good plan to effect the melting in a -water-bath, a simple kind of which, something after the fashion of a -glue-pot, would be made for a few pence by any tinman. - -Footnote 7: - - See Note G. - -The kidney which we are about to cut has, of course, gone through the -process of hardening already described (§ 5), and is now preserved in -spirit. A small piece, say half an inch square, is selected, removed -with forceps, and placed on a bit of blotting paper, when the surface of -the tissue will rapidly become dry (_only the surface_ must be allowed -to dry). It is the usual plan now to proceed at once to imbed it in the -melted paraffine. This is a most undesirable step, and gives rise at a -later stage of our proceedings to a great amount of trouble and -annoyance, for after sections have been cut from a tissue so imbedded it -will be found that portions of paraffine adhere to their edges with such -tenacity that in the case of many of them there is no effectual method -of removing the paraffine, short of soaking the sections in warm æther; -a very objectionable proceeding, for though the æther will undoubtedly -remove the paraffine, it will also dissolve out any fatty matters which -the section itself may naturally contain. All this annoyance may be -prevented by subjecting the tissue to a simple preparatory treatment -before it is imbedded in the paraffine. For this purpose prepare a very -_weak_ solution of gum arabic in water—twenty grains to the ounce. Into -this, by means of the forceps, dip for a few moments the already -_surface-dried_ tissue, taking special care not to squeeze it, or the -pressure will cause the spirit from its interior to remoisten the -surface, which would prevent the gum from adhering. We shall see the -value of this a little later on. Remove the tissue from the solution on -to blotting paper, when the superfluous gum will speedily drain off, and -in two or three minutes the _surface_ will have become quite glazy and -dry. Having melted some paraffine mixture in the water-bath, the tissue -held in the forceps must be plunged for an instant into the heated -liquid and immediately withdrawn, when the crust of paraffine with which -it is enveloped will promptly harden. Whilst this is taking place we may -make ready the microtome. Having by means of the milled head or handle -depressed the plug in the tube so as to leave a free opening about an -inch deep at its upper end, we must pour in the melted paraffine, which -by this time will have become a little cooler, until the cavity be about -half filled. The prepared tissue must now be introduced, care being -taken to place it in such a position that the sections may be cut in the -desired direction. The tissue must, if necessary, be held in position -with forceps or a needle point, till the imbedding material becomes hard -enough to give it due support. It is here to be remembered that it will -not be advisable to place the tissue in the centre of the tube—it will -be much more easily cut if placed rather nearer to that edge of the tube -which is situated next the operator in the act of cutting. More -paraffine is to be slowly added, until the tissue is completely covered; -even after this still more should be added, for it will be found that in -cooling the paraffine shrinks so as to leave a cup-shaped depression in -its centre, whereby portions of the tissue which were previously covered -are again laid bare. The best method of preventing this is to use the -paraffine at as low a temperature as possible, and to use plenty of it. -The microtome, with its contents, must now be removed to a cool place, -when the paraffine will soon become solidified. Whilst this is being -accomplished we may make our further preparations. The first thing we -require will be a large basin, full of freshly-filtered water, and -provided with a cover. A small beaker of methylated spirit, with a -dipping rod or pipette, will also be necessary. We must now see that the -section-knife is in thorough order, to ensure which it will be advisable -to give it a few turns on the strop. An ordinary razor will also be of -service. - -12. _Employment of Microtome._—The paraffine being sufficiently hard, we -will clamp the microtome on to the table, and seat ourselves on a chair -of convenient height before it. To our right stand the basin of water, -razor, and section-knife; the beaker of spirit to the left, and a cloth -on our knee. A few turns of the microtome screw having brought the -paraffine to the surface, a thick slice is to be cut off, and this -repeated until the imbedded tissue comes into view. This preliminary -work had best be done with the razor, as it is needless to subject our -section-knife to unnecessary wear and tear. By a fractional revolution -of the screw the tissue is now slightly elevated, and with the pipette -held in the left hand, a large drop of spirit is to be let fall upon its -surface. The section-knife, grasped firmly but lightly in the right -hand, is to be laid flat upon the cutting-plate of the machine, so as to -occupy the diagonal position shown in the figure. Two fingers of the -left hand are now laid gently upon the back of the blade, so as to give -it an equable support, whilst the knife with a rapid motion is pushed in -the combined direction of _forwards_ and to the _left_, so that the -blade in cutting the tissue will pass through it from point to heel. -Thus it will be observed that the stroke of the knife is _from_ the -operator—a far easier and more effective mode of cutting than the -reverse plan. The blade of the knife, having the section just cut, -either floating in a small pool of spirit on its surface or adhering -thereto, must now be immersed in the basin of water, when by a little -very gentle agitation of the knife the section will be floated off. And -now we shall find the great practical value of immersing the tissue in -gum before imbedding, for no sooner is the section disengaged from the -knife than the thin film of gum which separates the paraffine from it -becomes dissolved, and the section will be observed gradually to subside -to the bottom, leaving the paraffine floating upon the surface. After -carefully wiping the knife from all shreds of paraffine, the microtome -screw must again be partially revolved, more spirit applied to the -tissue, and another section being cut, it must be transferred to the -water as before, and so on, until a sufficient number of sections have -been obtained. As to how thin the sections should be cut, no general -directions can be given; each case must be regulated by its own -conditions. The denser the tissue, the thinner should the section be; -whilst certain substances of loose and spongy texture do not require the -sections to be particularly thin—it may be said, however, in a general -way that sections, and especially animal ones, _cannot be cut too thin_ -so long as they remain perfect and entire. If Professor Rutherford’s -microtome (as made by Gardner) be employed, the head of the screw will -be found to be graduated into divisions of slightly unequal value; the -sections will therefore be marked by corresponding variations of -thickness, so that amongst a number cut, there must be many of the exact -thickness to meet the requirements of any individual case. - - - [Illustration: DIAGRAM SHOWING DIAGONAL POSITION OF KNIFE IN - COMMENCING TO MAKE A SECTION.] - - -13. _Staining Agents._—Before proceeding to mount the sections which -have just been cut, it will be very advisable that they should be -submitted to the action of some staining fluid, in order to render more -clear and distinct their minute structure. Organic substances possess -the property of being able to absorb various colouring matters from -their solution, and to incorporate such colour into their own texture. -This power of attraction is not, however, possessed by all substances -indiscriminately, or to an equal extent. Some possess it in a high -degree, while others appear to be nearly, if not entirely, devoid of -such power. Hence it follows, that if we immerse an organic tissue (one -of our sections, for instance) of complex structure, in a suitable -staining fluid, the tissue will not become stained in an even and -uniform manner throughout, but the several portions of it will receive -varying depths of colour in accordance with the varying attractive power -of its several constituents. By this means we are enabled in stained -sections to discriminate by their difference of shade, minute and -delicate structures, which in the unstained condition it would be -difficult and often impossible to differentiate. For the purpose of -section-staining there are many agents in use, the most generally -suitable being carmine, logwood (§ 19), and aniline blue (§ 27); whilst -for special purposes chloride of gold (§ 28), pyrogallate of iron (§ -28), and several others are all of much value. - -14. _Carmine Staining._—In the case of animal sections, carmine is, as a -rule, to be selected, giving as it does most satisfactory and beautiful -results. Tissues may be stained with carmine by two different plans: in -the first, a strong solution is used, and the tissue subjected to its -action for a very short period only, whilst in the latter only very weak -solutions are employed, the time of immersion being considerably -prolonged. The rapid method, however, is not to be recommended, for the -strong carmine acts so powerfully upon the tissue as to give the various -elements comprising it no time, as it were, to exercise their power of -quantitive selection, but involves the whole in one uniform degree of -shadeless colour. By adopting the gradual method much better results are -obtained, each portion of the tissue being now at liberty to acquire its -own particular shade. Amongst the various formulæ for the preparation of -carmine fluid, none can be so safely followed as that devised by Dr. -Lionel Beale. It runs thus:—Place ten grains of the finest carmine in a -test tube, add thirty minims of strong liquor ammonia, boil, add two -ounces of distilled water, and filter; then add two ounces of glycerine, -and half an ounce of rectified spirit—this solution ought to be kept in -a well stoppered bottle. The best vessels in which to stain sections are -small jars of white porcelain, capable of holding about two fluid -ounces, and furnished with lids—they are much preferable to beakers or -watch glasses, for owing to the white background which they afford it is -very easy to watch how the staining is proceeding. The carmine solution -which we have just described is both too strong and of too great density -to be used in its pure state. It will, therefore, require to be diluted -with distilled water before use—the most useful degree of dilution being -attained by adding one part of stain to seven of water. Sections may be -placed in this solution for twenty-four hours, in which time they will -usually be found to have acquired a sufficient depth of colour. If, -however, the tissue be unusually difficult to stain, the time of -immersion may be doubled, or still further prolonged, without detriment -to the section. - - - [Illustration: SECTION SPOON.] - - -Having prepared and filtered some of this dilute solution, say an ounce, -let us proceed to stain with it those sections which we left in the -basin of water (§ 12). Here we are at once met by a practical -difficulty. How are the sections to be transferred from one vessel to -the other? This is ordinarily effected by means of a soft camel’s-hair -pencil. It is a method, however, open to grave objections, for the -sections so curl around the brush, and get entangled amidst its hairs, -that, notwithstanding every care, valuable sections not unfrequently -become torn during transit. Every difficulty at once vanishes if we -substitute for the brush a small implement, which any one can readily -make for himself. All that is necessary is to take a strip of -German-silver, or copper, of the thickness of stout cardboard, and about -seven inches in length by five-eighths of an inch in breadth. The sharp -angles are to be filed off and the edges carefully smoothed, whilst at a -distance of five-eighths of an inch from each extremity the end must be -turned up so as to form an angle of about 35°. One end must be left -plain, whilst the other, with the aid of a punch or drill, is to be -pierced with five holes about the thickness of a stocking needle[8] (see -Figure). If we now dip the perforated end of this spoon into the water -containing the sections, and gently agitate it, the sections will rise -from the bottom and float about. The spoon is now brought under one of -them, and being steadily lifted up the water flows downwards through its -apertures, and the section smoothly spreading itself out upon the spoon, -may be gently lifted out of the water, and on the spoon being dipped -into the staining fluid the section at once floats off. By this simple -means sections, however large, thin or delicate, may with ease be -conveyed from one fluid to another, with the utmost certainty of their -not being injured during the process. The sections having been in the -carmine fluid for about twenty-four hours, as much of the liquor as is -possible must be gently poured off, and its place supplied by a -freshly-filtered mixture of five drops of glacial-acetic acid to one -ounce of water, when in a few moments the carmine will become -permanently _fixed_ in the tissue, and the process of staining be -complete. - -Footnote 8: - - Dr. Klein describes a kind of “lifter,” made by bending some - German-silver wire, but as no drawing accompanies his description, it - is not easy to form a clear idea as to the form of this instrument. In - the recent and philosophical work of Schäfer, a lifter is figured, - which consists of a wire stem, having attached to its end a spade-like - blade. It will be observed that the spoon described in the text - differs from this lifter in having one end perforated, and in this - consists the real value of the implement. - -15. _Mounting Media._—The further treatment of the stained sections will -entirely depend upon the nature of the medium in which it is intended to -mount them. There are a variety of fluids in use for this purpose, the -principal being dilute alcohol (§ 26), dammar, or Canada balsam (§ -22-23), and glycerine. These, however, cannot be used indiscriminately, -each possessing certain special properties which render it suitable for -use with particular classes of objects only. Thus, weak spirit, having -no tendency to increase the transparency of objects, can advantageously -be used with such only as are already perfectly transparent. It is also -more suitable for the preservation of vegetable tissues (when the -retention of colour is no object) than animal, since with the latter it -has a tendency after a while to cause a kind of granular disintegration, -which ultimately destroys much of the usefulness of the preparation. -Dammar and Canada balsam, on the other hand, possess very great -refractive power, so that they are of great service in mounting objects -which require their transparency to be much increased. For this reason -they are not well adapted to the preservation of very delicate or -transparent tissues (unless previously stained), the minute details of -which become almost entirely obliterated when mounted in them. The chief -advantage possessed by these resinous media is, that tissues mounted in -them undergo no alteration, even after the lapse of many years. -Glycerine, in respect of its clarifying powers, occupies an intermediate -position between spirit and balsam, being much more refractive than the -former, infinitely less so than the latter. It is, therefore, of very -great value for the preservation of such tissues as possess a medium -degree of transparency, and which would become obscured if mounted in -spirit, or have their outlines rendered indistinct if preserved in -balsam. It is of the utmost value for mounting unstained anatomical -sections which, when put up in this medium, reveal such minute details -of structure as would readily have escaped observation had any other -agent been employed. It may also be used with stained sections, but in -this case the sections should be of extreme thinness, otherwise the -refractive power of the glycerine will be insufficient to render them -thoroughly transparent. The great drawback to the use of glycerine is -the extreme difficulty experienced in preventing its escape from beneath -the covering glass, for it unfortunately possesses such great -penetrating power that no cement hitherto devised can be thoroughly -depended upon for withstanding its solvent action for any considerable -length of time.[9] Attention to the instructions presently to be given -(§ 16) will, however, reduce this risk of leakage to a minimum. In the -use of glycerine Dr. Carpenter’s caution must ever be borne in mind, -viz., that, as carbonate of lime is in time dissolved by glycerine, this -agent ought never to be employed for the preservation of objects -containing such salt. - -Footnote 9: - - Note H. - -16. _Mounting in Glycerine._—To illustrate the method of using this -medium we will mount our present sections in glycerine. In the first -place we shall require a deep watch-glass, which is to be half filled -with glycerine diluted with an equal amount of distilled water. By means -of the spoon, one or more sections may be transferred into this, either -directly from the acetic acid solution (§ 14), or if, since cutting, -they have been preserved in spirit, they should first undergo a short -immersion in a large vessel full of water. The watch-glass should now be -covered with an inverted wine-glass, and put away for some hours, in -order that the sections may become thoroughly saturated with the dilute -glycerine. When this has been accomplished, a slide must be cleaned, and -one of the sections, with the aid of the _unpierced_ end of the spoon, -be transferred to its centre.[10] As the kind of section with which we -are now dealing is, or ought to be, of extreme thinness, no cell (§ 26) -is necessary. After tilting up one end of the slide, so as to drain off -as much of the weak glycerine as possible, a drop of Price’s best -glycerine must, with a glass rod or pipette, be allowed to fall gently -upon the section, so as to avoid the formation of air-bubbles. If any of -these, however, should be produced, they must be removed with the point -of a needle set in a wooden handle,[11] and the slide then covered with -a small bell-glass (or wine-glass). A circular cover is now to be -cleaned with a soft handkerchief, and after gently blowing from it any -adhering fibres of lint, etc., it will be advisable to hold the side of -the glass which is to come into contact with the preparation close to -the mouth, and breathe upon it, so as to cover it with moisture. The -cover held between the thumb and forefinger of the left hand must now be -applied by its edge near to the margin of the preparation, and the -surface of the cover directed in an inclined manner over it. Beneath the -overhanging edge of the cover the point of the needle, held in the right -hand, is now to be inserted (see Figure). By gently lowering the needle, -the cover will come into gradual contact with the slide, driving before -it a minute wave of glycerine, in which any air-bubbles that may have -become developed are usually carried off. A very considerable degree of -tact, however, is required to perform this little operation, simple as -it may appear, for the retreating wave of glycerine not unfrequently -floats out the section, either wholly or partially, from beneath the -cover. Air-bubbles, also (the _bêtes noires_ of this process), are -exceedingly likely to arise. When this happens the best plan to adopt -is, by means of the needle point, gently to raise and remove the cover, -apply another drop of glycerine to the section, and cover _with a fresh -piece of thin glass_. It will now be necessary to remove any superfluous -glycerine which may have collected around and near the cover. The great -bulk must be wiped away by means of a camel’s-hair pencil, slightly -wetted between the lips, any remaining stickiness being removed with a -bit of blotting paper which has been slightly damped. With a very small -camel’s-hair pencil, charged with solution of gelatine, a ring must be -made round the margin of the cover, of sufficient breadth to take in a -small tract of both cover and slide. As this cement is perfectly -miscible with glycerine, it readily unites with any of that fluid which -may ooze from beneath the cover, and which, in the case of any of the -ordinary varnishes, would act as a fatal obstacle to perfect adhesion. -To make the cement, take half an ounce of Nelson’s opaque gelatine, put -in a small beaker, add sufficient cold water to cover it, and allow the -mixture to remain until the gelatine has become thoroughly soaked. The -water is now poured off, and heat applied until the gelatine becomes -fluid, when three drops of creosote should be well stirred in, and the -fluid mixture transferred to a small bottle to solidify. Before use, -this compound must be rendered liquid by immersing the bottle containing -it in a cup of warm water. When the ring of gelatine has become quite -set and dry (which will not take long), every trace of glycerine must be -carefully removed from the cover and its neighborhood, by gently -swabbing these parts with a large camel’s-hair pencil dipped in -methylated spirit. After drying the slide a ring of Bell’s microscopical -cement may be applied over the gelatine, and, when this is dry, another -coat is to be laid on. If it be desired to give the slide a neat and -tasteful appearance, it is a very easy matter, by means of the -turn-table, to lay on a final ring of Brunswick black or white zinc -cement (§ 24). Every care has now been taken to render our preparation -permanent; but, to make assurance doubly sure, it will be well to follow -Dr. Carpenter’s advice, and, every year or so, to lay on a thin coating -of good gold-size.[12] - -Footnote 10: - - The appearance of a slide is vastly improved if the preparation be - placed _exactly_ in its centre. This may readily be done in the - following manner:—Take some very finely-powdered Prussian blue, and - rub it up in a mortar with a little of the weak gum solution (§ 11), - so as to form a thin blue pigment. A quantity of this should be made, - so as always to be at hand. A slide having been cleaned, the _best - surface_ is to be selected, and on the _reverse_ side, by means of the - self-centring turn-table, a small circle is to be drawn with a - camel’s-hair pencil, charged with the pigment. In the centre of this - ring, but on the opposite side of the slide, the section is to be - placed, when it of course will occupy a position exactly central. When - the slide comes to be finished, the blue ring may easily be removed - with a wet rag. - -Footnote 11: - - A _crochet-needle_ holder made of bone, and which may be bought at - the smallware dealers’ for about sixpence, makes an admirable handle - for microscopical needles. At one extremity there is a small cavity, - closed with a cap, for the storage of reserve needles, whilst the - other end terminates in a metal tip, provided with a crucial slit and - central perforation for the reception of the needle in actual use, and - so arranged that, by means of a small screw-nut, needles of various - sizes may be firmly held in position. - -Footnote 12: - - If square covers be employed, they may be fixed to the slide by a - simple method much in vogue in Germany. A thin wax taper is to be - lighted, and being partially inverted for a few seconds, the wax - surrounding the wick will become melted. After the slide has been - freed from excess of glycerine, a drop of this heated wax is allowed - to fall upon each corner of the cover, and a line of the melted wax - run along the margins of the cover between these points, so as - perfectly to surround it. If a good coat of white zinc cement be - subsequently laid over the wax a very durable, and not unornamental, - line of union will have been formed. - - - [Illustration: METHOD OF APPLYING COVER.] - - -17. _Use of Freezing Microtome._—Our preceding consideration of the -method of employing the microtome in conjunction with paraffine as an -imbedding agent (§ 11), will have formed a very suitable introduction to -the study of the somewhat more complicated process of imbedding the -tissue in gum, for section in the freezing microtome. This method is of -the utmost value to the practical histologist, for by its means he is -enabled with ease to possess himself of perfect sections of several -structures, the cutting of which, before the introduction of this -process, was always a matter of difficulty and anxiety. The freezing -microtome is especially valuable for the section of such substances as -from their extreme delicacy are liable to be injured by being imbedded -in paraffine—for instance, the delicate villi of the intestines becomes -very frequently, by the use of paraffine, denuded of their epithelium, -and the villi themselves not seldom become torn off or otherwise -damaged. The great value of the method is also very well seen in the -treatment of those tissues which, like the lung, are of such loose and -spongy texture as to offer insufficient resistance to the knife unless -their interstices have previously been filled up with some solid yet -easily cut material. As the space at our command is strictly limited, we -are precluded from entering as fully into this branch of section-cutting -as the importance of the subject demands and our own inclination would -lead us. To those who wish to become thoroughly conversant with the full -value of this method we cannot do better than recommend the perusal of -Professor Rutherford’s _Practical Histology_, 2d edition, than which, on -the whole subject of physiological microscopy, no treatise with which we -are acquainted is at once so plain, practical, and profound. - -18. _Employment of Freezing Microtome._—A very suitable object with -which to demonstrate the method of using this form of microtome will be -afforded us by a portion of intestine, say of the ileum of a cat or dog. -Suppose we have some of this in methylated spirit—let us select a piece -of about half an inch in length. Our first care will be to deprive this -of its spirit; for so long as the tissue remains impregnated with -alcohol it would, of course, be impossible to freeze it. We will, -therefore, throw it into a large basinful of water, and leave it there -for twenty-four hours, during which time it would be as well to change -the water once or twice. We shall now require a strong solution of gum. -This, which should have been made some time previously, may be prepared -by placing a quantity, say three or four ounces, of ordinary gum arabic -in a glass beaker, and adding sufficient water to cover it—the mixture -must be stirred occasionally with a glass rod until solution has taken -place, which will be in a few days. If _necessary_ a little more water -may be added, but so long as the gum will pour from vessel to vessel, it -cannot well be made too strong. Mucilage, by keeping, is very apt to -become sour and mouldy—this may be prevented by adding to each ounce of -the water with which it is prepared about half a grain of salicylic -acid. We now pour some of this mucilage into a small vessel—an egg cup -will answer very well—and into it transfer the piece of ileum from the -water. Here we must allow it to remain for a time sufficient to permit -of its becoming thoroughly saturated with the gum, for which purpose -some hours will be necessary. When this soaking has been accomplished we -will prepare the microtome, which we will assume to be Rutherford’s. In -the first place it will be necessary to remove the plug—which is to be -done by turning the handle connected with the screw until the plug rises -so high in its tube that it may be grasped with the fingers and removed, -when it is to be well smeared all over with sperm oil and replaced. This -is done to prevent any unpleasant adhesions taking place whilst the -freezing is going on. We must next depress the plug, so as to convert -the upper part of the tube into a kind of “well” of sufficient depth to -hold our specimen. It will now be very advisable to look carefully into -this _well_ and observe whether the plug fits accurately into the tube -(§ 8) for if there be any interval between the two it will give rise to -much subsequent annoyance, as the gum penetrating this interstice will -there become firmly frozen into irregular patches, which will so -interfere with the even gliding of the plug within its tube as to cause -the former to ascend in such an irregular and jerky manner as to be -utterly destructive of all accuracy in the cutting. If this defect be -observed, it may be at once remedied by dropping a small quantity of -gently heated paraffine into the _well_, which will effectually close up -any fissures. The microtome, by means of its clamping arrangement, must -now be firmly attached to the table, and a suitable vessel be placed on -the floor beneath it, so that it may catch the water which will issue -from the waste-pipe of the apparatus. The next requirement is a supply -of block ice and finely-powdered salt. A lump of the ice must be wrapped -in a towel, and crushed into small pieces; these, by means of a large -mortar, are to be further reduced to a very _fine powder_. Any attempt -to hurry over this troublesome part of the operation will lead to future -disappointment, for unless the ice be used in a very fine powder great -delay (at least) in the freezing will be the result. With the aid of a -small spoon the ice and salt are in alternate spoonsful to be conveyed -into the freezing-box of the machine, great care being taken that the -cavity under the cutting-plate and around the tube be thoroughly packed, -after which the uncovered portion of the box should also be well filled. -The _well_ is now to be filled with the strong gum to within a little -distance of its top, and a piece of sheet gutta-percha (such as shoe -soles are made of) being applied over the well, and kept in position by -a weight, we must wait until the freezing commences. In a short time we -shall notice that the gum has acquired a thick muddy appearance. The -tissue must now, by means of the forceps, be transferred to the well, -and there placed in such a position that the sections, when cut, shall -run in the desired direction. After more gum has, if necessary, been -added, so as completely to cover the tissue, the well is again to be -covered, and attention given to the freezing-box. As the mixture which -this contains becomes melted, it must constantly be renewed, care being -at the same time taken that the mouth of the discharge-pipe be kept -quite free, otherwise water accumulating in the box, the freezing -mixture will degenerate into a useless puddle. When the gum becomes -sufficiently hard to cut, this must be done much in the same manner as -if paraffine had been used (§ 12). In this case, however, no fluid will -be required, or must be used, to wet the knife with, and especial care -must be taken that in disengaging the sections from the knife into the -water they be not torn. These sections often adhere very tenaciously to -the blade, but if a little patience be exercised the water will soon -float them off in safety—much more safely than if any attempt be made to -liberate them prematurely. There is one circumstance connected with the -use of the freezing microtome which is rather annoying. The moisture of -the breath and atmosphere is apt to become condensed on the -cutting-plate, and here, mixed with accidental smears of gum, it becomes -frozen into a jagged and irregular sheet of ice, which not only -seriously interferes with the smooth play of the knife, but also -constitutes a real peril to its edge. As this evil cannot be avoided, -all we can do is, by constant wiping, to keep the cutting-plate clean -and free from this accumulation. This is best done with a bit of soft -rag _just moistened_ with spirit, but this must not come into contact -with any portion of the cylinder of frozen gum, else it will instantly -thaw it. When using the freezing microtome it is always advisable to -wear an apron, otherwise our clothes may receive considerable damage -from the constant splashing of the salt water, as it falls from the -waste-pipe into the vessel beneath it. After use, the microtome must be -well washed in plenty of cold water till every trace of salt be removed, -for if any of this remain it will quickly corrode the brass-work of the -instrument. The plug and screw, as also the section-knife, should be -well smeared with Rangoon oil before the machine is put away. - -19. _Logwood Staining._—The employment of logwood as a staining agent is -now becoming very general. It acts much in the same manner as carmine, -but the violet color which it produces is by many thought to be of a -more soft and agreeable character than that due to the action of -carmine. A valuable and very convenient property also which it possesses -is that it stains tissues very rapidly, and this without interfering -with that differential kind of coloration (§ 14) upon which the chief -value of all staining processes depends. A simple method of preparing -the logwood fluid is to mix an aqueous solution of extract of logwood -with a solution of alum (1 to 8) till the deep impure red colour has -become violet, and then to filter the mixture (Frey). This will stain -sections in about half an hour. This stain, though here mentioned for -the ease with which it may be made is, as a rule, very inferior to a -fluid prepared directly from hæmatoxylon, the alkaloid or active -principle of logwood. As, however, it is difficult and troublesome to -make the solution in this manner,[13] it will be advisable for the -student to purchase, ready prepared, such small quantity of the dye as -he may require. Small bottles may be obtained for a few pence of Mr. -Martindale, 10, New Cavendish Street, London, and from repeated trials -of this solution we can recommend it as producing excellent results. It -is a very strong fluid, and requires to be diluted before use. The -degree to which the dilution must be carried cannot, however, be very -accurately indicated, for all staining fluids of this nature possess the -very undesirable property of becoming decomposed by age. After the fluid -has been kept for some time, a portion of the colouring matter is thrown -out of solution, and becomes deposited upon the sides and bottom of the -vessel in which it is contained, hence the older the preparation, the -weaker it will have become. As the time required for staining with -logwood is but short, it is desirable that all the sections should begin -to be submitted to its action at the same time, otherwise some will -become more deeply stained than others. A good plan is to fill a small -porcelain jar (§ 14) with filtered water, and into this transfer the -sections. Whilst they are settling well down to the bottom, a mixture -must be prepared of half a drachm of Martindale’s solution (fresh) to -one ounce of distilled water, and everything got in readiness for its -immediate filtration. The water is now very gently to be poured off the -sections, and if care be exercised this may be done in such a manner as -to leave them undisturbed at the bottom, after removing almost every -drop of water. The diluted logwood fluid must now be _immediately_ -filtered upon the sections, so that they may run no risk of becoming -dry. In the present instance the staining may be allowed to proceed for -about thirty minutes, and this will be found a convenient time for the -immersion of the general run of animal sections. If the logwood fluid be -not quite fresh, either a little more of it will have to be added to the -water, or the time of immersion must be prolonged until the desired -depth of color has been produced. It is well whilst the staining is -going on gently to shake the vessel occasionally, so that the sections -may not remain in a heap at the bottom, but all be as fully as possible -exposed to the action of the dye. When the staining is judged to be -complete, the logwood solution must be gently poured off, leaving the -stained sections at the bottom of the jar, when they should be quickly -covered with methylated spirit, which will _fix_ the colour. We shall -now be able to see if the coloration obtained be perfectly satisfactory. -If not deep enough, it is very easy again to submit them to the action -of the dye for a few minutes longer. If on the other hand, and as more -frequently happens, the coloration should be too deep, the excess of -colour may readily be removed by transferring the sections for a short -time into some diluted acetic acid prepared by adding five drops of the -glacial acid to an ounce of water. The action of this should be -carefully watched, and when the colour has been reduced to the desired -tint the sections may be retransferred to the methylated spirit. - -Footnote 13: - - Should the student, however, determine to prepare this solution for - himself, he will find a good formula for the purpose in Schäfer’s - “Practical Histology,” p 176. Note I. - -20. _Absolute Alcohol._—As we purpose mounting the sections which have -just been stained, in Canada balsam, we will briefly consider the -preliminary treatment to which they must be submitted before this can be -effected. The object of this is to abstract from the tissue all its -water, for if any moisture be permitted to remain in the section it -will, when mounted in balsam, become obscured and surrounded by a kind -of opalescent halo, due to the imperfect penetration of the balsam into -the only partially dehydrated tissue. The old-fashioned plan of -dehydration was simple exposure to the air. The method now generally -adopted is to bring about the same result by means of absolute alcohol. -This fluid has such a strong affinity for water that tissues submitted -to its influence are rapidly and effectually deprived of any water they -may contain. Absolute alcohol in small quantity may be obtained from the -druggist at about sixpence per ounce. It will be necessary for the -student to provide himself with a little of this agent, say about two -ounces, the method of using which will very shortly be explained. -Absolute alcohol must be kept in a bottle with a very accurately-fitting -stopper, in order to prevent its absorbing moisture from the air. For -our purpose such a bottle, having a neck _as wide as possible_, is to be -selected. - -21. _Clove Oil._—After being thoroughly dehydrated the sections may, in -special instances (§ 48), be at once mounted in balsam; but, as a -general rule, it will be found necessary (particularly in the case of -animal sections) to treat them with some clarifying agent, in order to -remove the cloudiness and opacity which is (in part) due to their -previous immersion in alcohol. For this purpose turpentine, or any of -the essential oils, may be used: of these, oil of cloves is to be -specially recommended. It is rather expensive, ranging from sixpence to -one shilling per ounce: but, as a drop or two will be sufficient for -preparing each slide, only a small quantity—say half an ounce or an -ounce—need be procured. The most convenient vessel in which to keep the -oil is one of the small test bottles used by watchmakers. These bottles -are provided with a glass cap to exclude dust, and the stopper is -prolonged into a glass rod, which dips into the bottle. The use of this -rod and the method of employing the oil will be explained shortly. - -22. _Canada Balsam_, as ordinarily met with, is a thick resinous balm of -great viscidity, but readily rendered perfectly fluid by the application -of heat. Formerly, sections were mounted in this medium in its pure -state, but owing to the annoyance which was so constantly being -experienced from the tenacity with which intruding air-bubbles were held -by the viscous medium, this plan of mounting is rapidly falling out of -use.[14] It is now usual to employ the balsam in a diluted condition, -the two chief diluents being chloroform and benzole. As balsam, however, -often contains more or less moisture, it is desirable to drive this off -before adding the diluent. A very convenient way of doing so is to -expose some pure balsam to the heat of a cool oven for several hours, -when the balsam will be found to have assumed a hard, vitreous -character. It should now be broken into small pieces, these put into a -bottle, and some methylated chloroform added, which in a little while -will completely dissolve the hardened balsam. More chloroform is then to -be added, until a solution is obtained sufficiently thin to run through -filtering-paper. A glass spirit lamp must now be procured, having a -capacity of about two ounces, and provided with a cap. Into the -wick-holder of this (which must be made of porcelain) a hollow glass -tube is to be so fitted that its end dips into the lamp to within about -a third of the bottom. (See Fig.) The thin chloroform-balsam is now to -be filtered into this lamp, very fine filtering-paper—through which a -little chloroform has first been passed—being used for the purpose. When -the lamp is full it must (deprived of its cap) be put in a warm place -until sufficient of the chloroform has evaporated to leave behind it a -fluid of the consistence of thin syrup. - -Footnote 14: - - Although we cannot too strongly insist upon the use of - chloroform-balsam wherever practicable, yet it sometimes happens in - the mounting of substances of _considerable thickness_, that after all - the chloroform has evaporated an insufficient amount of balsam is left - behind to fill up the cavity between slide and cover. In such cases, - therefore, it is advisable to use pure balsam, which may be done in - the following manner. The object having been previously thoroughly - dehydrated by immersion in absolute alcohol, is to be thence - transferred to a little good turpentine, or benzole, where it should - remain until perfectly transparent. It is now to be placed in the - centre of a slide which has been gently warmed, and a drop or two of - _fresh_ fluid balsam added, the greatest care being taken to prevent - the formation of air-bubbles. Should such arise they must be touched - with the point of a heated needle, which will cause them to burst and - disappear. The chief difficulty of the process has yet to be - encountered in the application of the cover; for it is during this - procedure that the development of air-bubbles is most likely to take - place. This annoyance may, however, be entirely avoided by taking the - simple precaution of dipping the cover into turpentine before it is - applied (§ 16), when it will be found that “you can’t get air-bubbles, - even if you try.” The courtesy of Mr. J. A. Kay, of Chatham, enables - us to give our readers the benefit of this practical “_wrinkle_.” - - - [Illustration: SPIRIT LAMP ADAPTED TO CONTAIN BALSAM.] - - -23. _Mounting in Balsam._—Let us now return to our sections which, it -will be remembered, were left in methylated spirit (§ 19). These we will -now mount in balsam, and although, of course, any number may be -proceeded with at the same time, yet to avoid confusion, in the -following directions one section only will be spoken of. This section -then is, with the perforated spoon, to be transferred to the bottle of -absolute alcohol, where it may remain for about an hour—considerably -less time is _actually_ required, but as from constant use the spirit -becomes weakened, it is as well to be on the safe side. It must now be -removed to the centre of a clean glass slip, and here the _plain_ end of -the spoon comes into use. If this be employed for effecting the -transfer, it will be found that when the section is being removed from -the alcohol it will bring along with it a small pool of the spirit. A -slight touch of the needle applied to the edge of the section will cause -it to float from the spoon on to the slide, at the same time carrying -the pool of alcohol with it, in which it will gently spread itself out -upon the slide without the faintest risk of injury. The superfluous -spirit is now to be drained off, and just as the section is becoming -glazed and sodden-looking (_not dry_) we must, by means of the long -glass stopper (§ 21), apply to it a large drop of clove oil. The oil, -however, should not be placed on the section, but be allowed to drop on -to the slide near to its margin. By gently tilting the slide the oil -will gradually insinuate itself _beneath_ the section and slowly ascend -through it to the surface. The slide should now be covered with a -bell-glass (or wine-glass), and about two minutes allowed for the oil -thoroughly to saturate the section. As much as possible of the -superfluous oil must then be drained off, and the remainder removed with -blotting paper. By means of the glass rod a small quantity of -chloroform-balsam is now taken from the spirit lamp which contains it, -and allowed gently to fall upon the section, which must then be covered -with a thin glass circle in the manner previously described (§ 16). When -the object is very fragile, it is a good plan, after draining off the -clove oil, to apply the cover directly upon the section, and then to -place a drop of the balsam near to the edge of the cover. This, by -capillary attraction, will speedily diffuse itself beneath the cover, -flowing over and surrounding the object, without in the slightest degree -disturbing its position. If, during the process of mounting, any -air-bubbles arise, we may view their development with equanimity, being -well assured that as the chloroform evaporates they too will quickly -disappear. When the mounting is completed, the slide should be roughly -labelled and placed on a warm mantel-piece for a few days to dry. - -24. _Finishing the Slide._—In the course of two or three days it will be -advisable to take an old penknife, and after heating the blade in the -flame of a spirit lamp, gently to run the point of it round the margin -of the cover, so as to remove any excess of balsam which may have oozed -from beneath it. In a few days more, any remaining balsam may be -carefully scraped away with a cold knife. All remaining traces of balsam -are then to be removed from around the cover by means of a rag _just -moistened_ with methylated spirit, or, what is better, with a mixture of -equal parts of spirit and æther, after which the slide is to be -thoroughly washed in cold water. The slide is now in reality finished, -but, in order to give it a smart appearance, it is usual, with the -assistance of the turn-table, to run a ring of colored varnish round the -covering glass. A very useful varnish for the purpose is the _white zinc -cement_. To prepare this, dissolve an ounce of gum dammar in an ounce of -turpentine by the aid of heat. Take one dram of oxide of zinc and an -equal quantity of turpentine; rub them up together in a mortar, adding -the turpentine drop by drop, so as to form a creamy mixture perfectly -free from lumps or grit. One fluid ounce of the dammar solution -previously made must now gradually be added, the mixture being kept -constantly stirred (_Frey_). The cement, when made, should be strained -through a piece of fine muslin, previously wetted with turpentine, into -a small wide-necked bottle, which, instead of having a cork or stopper, -should be covered with a loose metal cap. Instead of a bottle, the -varnish may be kept in one of the collapsible tubes used by artists; but -though this plan is highly recommended by many, it is not without its -disadvantages. If the varnish becomes thick by keeping, a few drops of -turpentine or benzole well stirred in will soon reduce it to a suitable -consistence for use. - ------------------------------------------------------------------------- - - - - - PART II. - -25. _Special Methods._—Having in the preceding pages entered at some -length into the general subject of section-cutting, it remains for us -now to consider those special methods of preparation which the -peculiarities of certain objects demand. In order to keep the bulk (and -consequent price) of this manualette within due bounds, we shall, -without further preface, proceed to the description of these methods, in -doing which every endeavour will be made to employ such brevity of -expression as may be consistent with perfect clearness of meaning. As -the most convenient plan, the objects here treated of will be arranged -in alphabetical succession. - -26. _Bone._—Both transverse and longitudinal sections should be -prepared, the former being the prettier and most interesting. After -prolonged maceration in water, all fat, etc., must be removed and the -bone dried, when as thin a slice as possible is to be cut off in the -desired direction, by means of a very fine saw. If the section so -obtained be placed upon a piece of smooth cork it may, with the aid of a -fine file and the exercise of care, be further reduced in thickness. It -is then to be laid upon a hone moistened with water, and being pressed -gently and _evenly_ down upon it with the tip of the finger (protected, -if necessary, by a bit of cork or gutta-percha), it must be rubbed upon -the stone until the desired degree of thinness has been attained. -Finally, in order to remove scratches and to polish the section, it -should be rubbed upon a dry hone of very fine texture, or upon a strop -charged with putty-powder. After careful washing in several waters the -section must be allowed thoroughly to dry, when it may be mounted by the -_dry method_ in the following manner:—A ring of gold-size must, by means -of the turn-table, be drawn in the centre of a slide, and the slide put -away in a warm place for several days (the longer the better), in order -that the ring may become perfectly dry and hard. When this has been -accomplished the section is to be placed in the centre of the ring, and -a covering circle of the requisite size having been cleaned, this must -have a _thin_ ring of gold-size applied round its margin. The cover is -now to be placed in position and gently pressed down, a spring clip -being employed, if necessary, to prevent it from moving. In about -twenty-four hours another layer of the varnish should be applied, and -the slide afterwards finished in the manner already described (§ 24). -The above method is also applicable to the preparation of sections of -_teeth_ and also of _fruit-stones_ and other hard bodies, which are -incapable of being rendered soft enough for cutting. - -As the process just described, however, is both troublesome and tedious, -it is much better for ordinary purposes to have recourse to the -_decalcifying method_, by which means sections in every way suitable for -the examination of the essential structure of bone may be obtained with -ease. To carry out this plan a piece of fresh bone should be cut into -small pieces and placed in a solution made by dissolving 15 grains of -pure chromic acid in 7 ounces of distilled water, to which 30 minims of -nitric acid s. g. 1.420 are afterwards to be added. Here they should -remain for three or four weeks, or until the bone has become -sufficiently soft to cut easily, the fluid being repeatedly changed -during the process. From this solution they must be transferred to -methylated spirit for a few days, when a piece may be selected, imbedded -in paraffine, and cut in the microtome (§ 12). Some of the sections -should be mounted, unstained, in spirit. For this purpose a cell of -gold-size, as above described, must first be prepared and filled _full_ -of a mixture of spirit of wine one part, and distilled water three -parts. Into this the section must be carefully placed and the cover -applied, the same precautions for the exclusion of air-bubbles being -taken which were recommended when speaking of mounting in glycerine (§ -16). When the cover is in position a ring of gold-size must be laid on, -repeated when dry, and the slide afterwards finished in the ordinary -manner. It will also be advisable to stain some of the sections with -carmine (§ 14), or picro-carmine (§ 42), and mount them in glycerine. -_Teeth_ may also be treated by the decalcifying method, but in this case -it must be remembered that the enamel will dissolve away. - -27. _Brain._—The best hardening fluid is that recommended by Rutherford, -and is made by dissolving 15 grains of pure chromic acid and 31 grains -of crystalized bichromate of potash in 43 ounces of distilled water. -Small pieces of brain, which have previously been immersed for -twenty-four hours in rectified spirit, should be placed in about a pint -of this solution, where they must remain for five or six weeks, the -fluid being repeatedly changed during the process. If by this time they -are not sufficiently hard the induration must be completed in alcohol. -Sections are easily cut in the microtome by the paraffine method (§ 12). -These may advantageously be stained in a solution of aniline blue, made -by dissolving 1-1/2 grain of aniline blue in 10 ounces of distilled -water, and adding 1 drachm of rectified spirit (_Frey_). As this stain -acts very rapidly two or three minutes’ immersion will generally be -found long enough. The sections must then be mounted in balsam (§ 23). - -28. _Cartilage._—The method to be employed in the preparation of -cartilage will entirely depend upon the nature of the staining agent, to -the action of which the sections are to be submitted. Thus, if the -elegant _gold method_ is to be followed, it is necessary that the -cartilage should be perfectly fresh; whilst if any of the other staining -agents are to be employed the tissue may have been previously preserved -in alcohol. An excellent object on which to demonstrate the gold process -is to be found in the articular cartilage of bone. It is a very easy -matter to obtain from the butchers the foot of a sheep which has just -been killed. The joint is to be opened, and the bones dissociated, when -they will be seen to have their extremities coated with a white -glistening membrane—this is the _articular cartilage_. Exceedingly thin -slices must be at once cut from it, and as only small sections are -required, a sharp razor may be used for the purpose, the blade being -either dry or simply wetted with distilled water. The sections as cut -are to be transferred to a small quantity of a half per cent. solution -of chloride of gold in a watch glass. Chloride of gold may be purchased -in small glass tubes hermetically sealed, each tube containing 15 -grains, and costing about 2s. If, however, the student requires only a -small quantity of the staining fluid he need not be even at this small -expense, for as photographers for the requirements of their art always -keep on hand a standard solution of chloride of gold of the strength of -one per cent., a little of this may readily be obtained, and diluted to -the required degree. After the sections have been exposed to the action -of the staining fluid for about ten minutes they may be transferred to a -small beaker of distilled water, and exposed to diffused light for about -twenty-four hours, when they must be mounted in glycerine (§ 16). - -Sections of cartilage may also be examined, without being stained, in -which case the field of the microscope should be only very feebly -illuminated. Or carmine staining (§ 14) may be resorted to—these -sections show well in glycerine, or if the staining be made very deep, -even Canada balsam may be employed, and with fair results. - -Microscopists are indebted to Dr. Frances Elizabeth Hoggan for the -description of a new method of staining, which we have found especially -suited to the treatment of cartilage. The agent employed is _iron_, and -the process, which is very simple, is as follows. Two fluids are -necessary—(1) tincture of steel; (2) a two per cent. solution of -pyrogallic acid in alcohol. A little of the former is to be poured into -a watch glass, and into this the sections, after having been previously -steeped in alcohol for a few minutes, are to be placed. In about two -minutes the iron solution is to be poured away and replaced by solution -No. 2. In the course of a minute or two the desired depth of colour will -have been produced, when the sections are to be removed, washed in -distilled water, and mounted in glycerine. The results obtained by this -process are very beautiful, the colour produced being a very fine -neutral tint, of delightful softness. The process also answers admirably -in the case of morbid tissues, and we have now in our possession some -sections of ulcerated cartilage tinged by the iron method, in which the -minute changes resulting from the ulcerative disintegration are brought -out with wonderful distinctness. - -As the structure of cartilage differs according to its purpose and -situation, the student will find his time profitably employed in a -careful examination of the following forms (α) _hyaline_—articular and -costal; (β) yellow fibro-cartilage—epiglottis, or external ear; (γ) -_cellular_—ear of mouse. Sections of the _intervertebral_ ligaments -should also be made, in which the different kinds of cartilage may be -examined side by side with each other. - -29. _Coffee Berry_ affords sections of great beauty. The _unroasted_ -berry should be soaked for hours or days in cold water until -sufficiently soft; then imbedded in paraffine, and cut in the microtome -(§ 12), the section being made in the direction of the long axis of the -berry. Put up in glycerine, or stain rather strongly with carmine, and -mount in balsam. The same method of treatment may also be applied to -other hard berries or _seeds_. - -30. _Fat._—Adipose tissue may be hardened in alcohol, cut in paraffine, -and mounted in glycerine. If the tissue has been injected the sections -may be mounted in balsam, and are then very beautiful objects, showing -the capillary network encircling the fat cells. - -31. _Hair._—Longitudinal sections are readily made by splitting the hair -with a sharp razor. It is more difficult to cut the hair transversely. -This, however, may easily be done in the following manner. The hairs -having previously been well soaked in æther to remove all fatty matters, -a sufficient number of them must be selected to form a bundle about the -thickness of a crow quill. This bundle, after being tied at each -extremity with a bit of thread, is to be immersed for several hours in -strong gum (§ 18,) to which a few drops of glycerine have been added. On -removal, the bundle must be suspended by means of a thread attached to -one end of it, in a warm place until sufficiently hard, when it is to be -imbedded and cut in paraffine (§ 12). Each section, as cut, is to be -floated off the knife into methylated spirit. From this it is with the -aid of the spoon (§ 14) to be transferred to a slide, the spirit tilted -off, a drop of absolute alcohol added, when, after a minute or two, this -also is to be drained off, the section treated with clove oil, and the -mounting completed as described in § 23. - -32. _Horn_ varies very much in consistence, in some instances having a -cartilaginous character, whilst in others it is almost bony. In the -latter case, sections will have to be ground down in the manner -explained when speaking of bone (§ 26). Where the texture is less dense, -recourse may be had to prolonged steeping in hot or boiling water; in -some cases it will be necessary to continue the immersion for several -hours. When sufficiently soft the piece of horn may, by means of bits of -soft wood, be firmly wedged into the tube of the microtome, and sections -cut with a razor, or what is better, with a broad and very sharp chisel. -The sections are to be put between glass slips, held together by -American clips (or pegs), and put away for two or three days in order to -become thoroughly dry. After well soaking in good turpentine or benzole, -they must be transferred to slides, the superfluous turpentine drained -off, and chloroform-balsam added, etc. (§ 23). Sections of horn should, -of course, be cut in different directions, but for examination with the -polariscope those cut transversely yield by far the most magnificent -results. _Hoofs_, _whalebone_, and allied structures should also be -treated by the above method. - -33. _Intestine._—The method to be pursued with _sections_ has already -been described (§ 18). The ileum, however, is a very pretty object when -a portion of it is so mounted as to show the _villi erect_. To do this -it is necessary to cement to the slide, by marine glue, a glass cell of -sufficient depth. This should have been prepared some time beforehand, -so that the cement may be perfectly dry and hard. The cell is now to be -filled with turpentine, and the piece of ileum (having been previously -passed through methylated spirit and absolute alcohol into turpentine) -is gently placed into it, having the villi uppermost; pour some pure and -rather fluid balsam on the object at one end, and gradually incline the -slide, so as to allow the turpentine to flow out at the opposite side of -the cell, till it is full of balsam. Then take a clean cover, and having -placed upon it a small streak of balsam from one end to the other, allow -it gradually to fall upon the cell, so as to avoid the formation of -air-bubbles (§ 17), and finish the slide in the usual manner.[15] Or, -the intestine may be dried, and mounted _dry_, in a cell with a -blackened bottom, for examination as an opaque object. - -Footnote 15: - - Ralf. - -34. _Liver._—Small pieces of liver may be very successfully hardened by -immersion in alcohol, beginning with weak spirit and ending with -absolute alcohol. Cut and mount as usual. - -35. _Lung_ must be prepared in chromic acid (§ 5). For the cutting of -sections the freezing microtome (§ 18) is of especial value, and should, -therefore, be used. If, however, the student be not provided with this -instrument, he must proceed as follows. A small piece of lung, -previously deprived of all spirit, is to be immersed until thoroughly -saturated in solution of gum (§ 18). A small mould of bibulous paper (§ -2), only just large enough to receive the piece of tissue, having been -prepared and filled with the mucilage, the specimen is to be transferred -to it. The mould, with its contents, is now to be placed in a saucer, -into which a mixture of about 6 parts of methylated spirit and 1 part of -water (_Schäfer_) is to be poured until the fluid reaches to within -about a third of the top of the paper mould. In the course of several -hours the surface of the mucilage will begin to whiten and solidify. As -soon as this occurs more dilute spirit must be poured into the saucer, -until the mould is completely submerged. In a day or two the gum will be -found to have acquired a suitable consistence for cutting, when it must -be removed from the spirit, the paper mould peeled off, and the mass -imbedded and cut in paraffine, the sections being afterwards treated as -if they had been obtained by the freezing method (§ 18). If the -solidification of the gum should proceed too slowly, a few drops of pure -spirit may be added to the contents of the saucer. If, on the other -hand, the gum should become overhard, it will be necessary to put into -the saucer a few drops of water, and repeat this until the required -consistence be obtained. - -36. _Muscle._—Harden in chromic acid, and cut in paraffine. Transverse -sections may be made to show the shape of the fibrils. Longitudinal -sections will only be required in the case of injected tissues, when -such sections will be found very elegant, showing, as they do, the -elongated meshes of capillaries running between and around the muscular -fasciculi. Mount in glycerine or balsam. To see the transverse striæ -characteristic of voluntary muscle, a very good plan is to take a bit of -pork (cooked or fresh), and by means of needles to teaze it out into the -finest possible shreds. If these be examined in water or glycerine, the -markings will be shown very perfectly. - -37. _Orange-peel_, common object though it be, is not to be despised by -the microscopist. Transverse sections must be prepared by the gum method -(§ 35). These sections are not to be subjected to the action of alcohol -(as this would destroy the colour), but after _drying_ between glass -slides they must be soaked in turpentine and mounted in balsam. We shall -then have a good view of the large globular glands whose office it is to -secrete that essential oil upon which the odor of the orange depends. - -38. _Ovary_ may be prepared in the same manner as liver (§ 34). -Sections, which are to be cut in paraffine, may be stained with carmine, -and mounted in glycerine or balsam. Apart from all scientific value, we -know of no slide for the microscope which, even as a mere object of -show, surpasses in beauty a well-prepared section of _injected_ ovary, -showing the wondrous Graafian vesicles, surrounded by their meandering -capillaries. - -39. _Porcupine Quill._—Soften in hot water, cut in paraffine, and mount -in balsam. Much (in our opinion _too_ much) lauded as an object for the -polariscope. - -40. _Potato._—From the large amount of water which it contains thin -sections cannot be cut from the potato in its natural state. It must, -therefore, be partially desiccated, either by immersion in methylated -spirit for a few days or by exposure to the air. Sections may then -readily be obtained by imbedding and cutting in paraffine. Such sections -mounted in balsam are very beautiful, the starch being seen _in sitú_, -whilst if polarized light be employed each granule gives out its -characteristic black cross. - -41. _Rush_ is to be prepared and cut as orange-peel (§ 37). Transverse -sections of this “weed” furnish slides of the most exquisite beauty. - -42. _Skin._—To prepare skin for section a piece is to be selected which, -after having been boiled for a few seconds in vinegar, must be stretched -out on a bit of flat wood, and being maintained in position by pins be -allowed to remain until thoroughly dry. Then imbed in paraffine, and cut -_exceedingly_ thin transverse sections. These may be stained in carmine, -but more beautiful results are obtained if picro-carmine be employed. -Sections of skin, when stained by this agent are much increased both in -beauty and instructiveness; for the several constituents of the tissue -becoming tinged with different colours are readily distinguishable from -each other, whilst the contrast of colouring forms a pleasing picture to -the eye. The method of preparing picro-carmine is very simple, though it -sometimes yields a solution not altogether satisfactory. The best -formula with which we are acquainted is that given by Rutherford,[16] -and if due care be taken in following it out failure will generally be -avoided. “Take 100 c.c. of a saturated solution of picric acid. Prepare -an ammoniacal solution of carmine, by dissolving 1 gramme in a few c.c. -water, with the aid of excess of ammonia and heat. Boil the picric acid -solution on a sand bath, and when boiling add the carmine solution. -Evaporate the mixture to dryness. Dissolve the residue in 100 c.c. -water, and filter. A clear solution ought to be obtained; if not, add -some more ammonia, evaporate, and dissolve as before.” Sections may be -exposed to the action of this fluid for a period varying from fifteen to -thirty minutes, then rapidly washed in water, and mounted in glycerine. -They may also be mounted in balsam, care being taken in that case to -shorten as much as possible the period of their immersion in alcohol, so -that no risk may be run of the picric acid stain being dissolved out. - -Footnote 16: - - “Practical Histology,” 2d edit. p. 173. - -If it is intended to study the structure of the skin with anything like -thoroughness, portions must of course be examined from different -localities, in order that its several varieties and peculiarities may be -observed. Thus the _sudoriforous_, or sweat glands, may be found in the -sole of the foot, whilst the _sebaceous_ glands are to be sought in the -skin of the nose. The _papillæ_ are well represented at the tips of the -fingers,[17] whilst the structure of the shaft of the _hair_, together -with that of the follicle within which its root is enclosed, as also the -muscles by which it is moved, are to be studied in sections of skin from -the scalp or other suitable locality. - -Footnote 17: - - It is well, in connection with these papillæ, to bear in mind a fact - pointed out by _Frey_, namely, that the tips of the fingers frequently - become, _post-mortem_, the seat of extensive natural injections; - hence, in sections from this region, we frequently obtain good views - of distended capillaries without having been at the trouble of - previously injecting them.—_Frey_, “Microscopical Technology.” - -43. _Spinal Cord._—The spinal cord, say of a cat or a dog (or if -procurable, of man), after being cut into pieces about half an inch in -length, may be hardened in the usual chromic acid fluid (§ 5). As it is -peculiarly liable to overharden and become uselessly brittle, the -process must be carefully watched. Its further treatment is the same as -that of brain. These sections may be stained very satisfactorily by the -_ink process_, for communicating details of which we are indebted to the -kindness of Dr. Paul, of Liverpool. The agent usually employed is -Stephenson’s blue-black ink, which, for this purpose, must be quite -fresh. As in the case of carmine, two methods of staining may be -adopted—either rapid, by using concentrated solutions, or more -prolonged, according to degree of dilution. For the reasons previously -given (§ 14), slow methods of staining are always to be preferred, as -yielding the most beautiful results, yet, for the purposes of -preliminary investigation, it is often convenient to have recourse to -the quick process. To carry out the latter plan, an ink solution of the -strength 1 in 5—10 parts of water is to be freshly prepared, and the -sections exposed to its action for a few minutes. For gradual staining -the dilution must be carried to 1 in 30—50, and the time of immersion -prolonged to several hours, the sections being occasionally examined -during the staining, so that they may be removed just as they have -acquired the desired tint. When a satisfactory coloration has been -obtained, the preparations should be mounted in dammar or balsam (§ 23). -One advantage of this method of staining is, that definition is almost -as good by artificial light as by day. - -44. _Sponge_ may readily be cut after being tightly compressed between -two bits of cork; or its interstices may be filled up by immersion -either in melted paraffine (§ 11) or in strong gum (§ 18), and then cut -as usual. - -45. _Stomach_ requires no special method of hardening (chromic acid). -Sections should always, when practicable, be cut in the freezing -microtome. In default of this, proceed in the manner as directed for -lung (§ 35). Both vertical and horizontal sections will, of course, be -required. If the preparation has been injected, the latter are -particularly beautiful. Stain with carmine or aniline blue (§ 27), and -mount—if for very close study, in glycerine—if injected and for a “show” -slide, use balsam. - -46. _Tongue._—Harden in chromic acid, imbed and cut transverse sections -in paraffine. As, however, the paraffine is apt to get entangled amongst -the _papillæ_, whence it is afterwards with difficulty dislodged, it -will be as well before imbedding to soak the tongue in strong gum for a -_few minutes_, and afterwards immerse in alcohol till the gum becomes -hardened, so that the delicate papillæ may thus be protected from the -paraffine by a surface-coating of gum. The best staining agent is -picro-carmine (§ 42). Sections of _cat’s_ tongue near the root, when -thus stained, furnish splendid objects. Sections should also be made of -the _taste-bulbs_, found on the tongues of rabbits. These are small oval -prominences, situated one on each side of the upper surface of the -tongue near its root. They should be snipped off with scissors, and -vertical sections made in the direction of their long axis. Stain with -carmine or picro-carmine, and mount in glycerine or balsam. - -47. _Vegetable Ivory_.—After prolonged soaking in cold water may readily -be cut in the microtome. The sections should be mounted in balsam, and -though not usually regarded as polariscopic objects, nevertheless, when -examined with the _selenite_, yield very good colours. - -48. _Wood._—Shavings of extreme thinness may be cut from large pieces or -blocks of timber, by means of a very sharp plane. In this way very good -sections may be procured of most of the common woods, as oak, mahogany, -“glandular wood” of pine, etc. Where however, the material to be -operated upon takes the form of stems, roots, etc., of no great -thickness, they should, after having been reduced to a suitable -consistence (§ 4), be imbedded in paraffine, and cut in the microtome. -Before imbedding it must not be forgotten to immerse the wood to be cut -in weak gum-water (§ 11), this precaution being of great importance, -especially in the case of stems, etc., the bark of which is at all rough -and sinuous. If the sections are to be mounted _unstained_, they are -usually put up in weak spirit (§ 26). A very general method also of -dealing with this class of objects is to mount them _dry_ (§ 26). This -plan, however, cannot be recommended, for however thin the sections may -be, the outlines, when this process is adopted, always present a -disagreeable black or blurred appearance. To avoid this we may have -recourse to Canada balsam, but the ordinary method of employing it must -be slightly modified, a drop of chloroform being substituted for the -clove oil (§ 23), otherwise this latter agent will cause the section to -become so transparent as to render minute details of structure difficult -to recognize. A better plan, perhaps, is to stain the section with -carmine or logwood, and mount in balsam by the ordinary process. The -best course to follow, however, especially in the case of transverse -sections, is the _double staining_ method.[18] For this purpose the -sections in the first place must be subjected to the action of a -solution of chloride of lime (1/4 oz. to a pint of water) until they -become thoroughly bleached. They must then be soaked in a solution of -hyposulphite of soda (one drachm to four ounces of water) for an hour, -and after being washed for some hours, in several changes of water, are -to be transferred for a short time to methylated spirit. Some red -staining fluid is now to be prepared by dissolving half a grain of -Magenta crystals in one ounce of methylated spirit. A little of this -solution being poured into a small vessel of white porcelain (§ 14), the -sections are to be immersed in the dye for about thirty minutes. They -are now to be removed, and after _rapid_ rinsing in methylated spirit to -remove all superfluous colour, they must be placed in a blue staining -fluid made by dissolving half a grain of aniline blue in one drachm of -distilled water, adding ten minims of dilute nitric acid and afterwards -sufficient methylated spirit to make two fluid ounces. The sections must -be permitted to remain in this solution for a very short time only, one -to three minutes being generally sufficient, for as the action of the -dye is very energetic, it will, if too long exposure be allowed, -completely obliterate the previous coloration by the magenta. After -being again _rapidly_ rinsed in methylated spirit, as much of this as -possible must be drained off, and the sections put into oil of -_cajeput_, whence, in an hour, they may be transferred to spirits of -turpentine, and after a short soaking, mounted in balsam. - -Footnote 18: - - See a paper by Mr. Styles in the “Pharmaceutical Journal,” also - “Monthly Microscopical Journal” for August, 1875. [For a very - exhaustive paper on this subject by the late Dr. Beatty, of Baltimore, - Md., see “American Journal of Microscopy” for June, 1876. - -If the student will carefully carry out the above process, his trouble -will be amply repaid by the beautiful results obtained, for by its means -he may, with ease, prepare for himself a series of slides of such value -as to constitute a worthy addition to his cabinet. - -The preceding list by no means represents all the objects, sections of -which will be found interesting to the microscopic student. Such was not -its purpose—had it been so, the enumeration might have been prolonged -almost indefinitely. The end in view was to bring under the notice of -the reader only those substances the cutting of which is accompanied by -difficulty; and even of this class the space at our disposal has been so -limited that we have been unwillingly compelled to pass over many, and -dwell only on such as possess a typical character. - ------------------------------------------------------------------------- - - - - - NOTES. - - ---------- - - NOTE A., Page 14. - -RANGOON oil is not found in this market. It is a variety of naphtha or -petroleum found at Rangoon, in Asia, and contains a variable percentage -of solid paraffin. Kerosene with a very little paraffin dissolved in it, -would undoubtedly answer the same purpose. - -Good sperm oil or tallow (free from salt) will serve quite as well. It -is scarcely necessary to caution the reader that all oily matter should -be removed from the knife before it is used for cutting sections. This -is best effected by dipping it in hot water and carefully wiping it. - - NOTE B., Page 15. - -METHYLATED spirit is alcohol which contains a small percentage of -methyl. This renders it unfit for use in the manufacture of liquors or -even chloroform, but does not injure it as a preservative fluid. The -scientific men of Great Britain have the privilege of obtaining this -fluid free from duty, and consequently they make very general use of it. -In this country the student of science has no such privilege, and must -use the more expensive alcohol. This however is but of a piece with -other restrictions placed upon scientific pursuits in this country, -where men like Marshall Jewell and Hannibal Hamlin have influence enough -to pass laws which prohibit the exchange by mail of microscopic -specimens, which pass freely in every other civilized country. - -True methyl alcohol, or methylated spirits, is not to be had in this -country, and therefore whenever this liquid is directed to be used in -English books the American microscopist must substitute good alcohol. -What is sold for “methyl alcohol” is wood spirit or wood naphtha, and -will not serve the purposes of the microscopist, though it answers well -enough for spirit lamps, making varnishes, etc. - - NOTE C., Page 20. - -THE method described in the text is generally known as the “free-hand” -method, and although it is not generally employed for the production of -cabinet specimens or slides that are intended for sale, yet it possesses -so many advantages that every student should endeavor to acquire the art -of cutting sections without the use of the microtome. For purposes of -study such sections are quite equal to the best of those usually found -on sale, and for the encouragement of beginners we may add that we have -seen sections cut by the free-hand method which for size, thinness and -accuracy, excelled any that we have ever seen produced with the -microtome. Indeed Schäffer distinctly affirms that no microtome can -equal the skilled hand in the production of thin sections. - - NOTE D., Page 22. - -THE mere existence of a binding screw should be no objection, and where -bushings are employed it is sometimes necessary. But as the author well -observes, a binding screw cannot be used to secure histological -preparations. - - NOTE E., Page 22. - -A STILL better system is where the section-knife is held in a frame -which slides on the plate so that the edge is kept just above the -surface. In this way the edge of the knife is never dulled by grinding -on glass or metal. A common mistake in this form, however, is to raise -the cutting edge too far above the surface of the plate. This gives rise -to great irregularities. - - NOTE F., Page 22. - -AS the size of the sections which it may be desired to cut, varies -within wide limits, the best microtomes made in this country are -furnished with as many as three tubes or “bushings,” fitting one within -the other, and in this way the hole may be partially filled up and thus -reduced in size. This enables us to obtain a range of from one inch and -a quarter, suitable for large histological preparations, to one-eighth -of an inch for such objects as hair sections. - - NOTE G., Page 37. - - KNIVES FOR CUTTING SECTIONS. - -SUCCESS in cutting sections depends more upon the excellence of the -knife that is used than upon any other one point, and therefore the art -of keeping the knife in good order is one which should be acquired by -every microscopist, even at the cost of considerable time, study and -labor. As a stepping stone to the acquisition of this art, there are -certain general principles which must be thoroughly understood before we -can hope for success in practice. These principles are simple, and when -once clearly stated, quite obvious, but they are frequently overlooked. - -Cutting instruments act in two ways—either as simple wedges or as a -series of wedges, the latter being generally known as the saw-like -action. It is frequently stated in school philosophies that the edges of -_all_ cutting instruments are toothed like a saw, and that they act like -a saw; this is evidently not the case with many, such as the axe, the -chisel, the plane, etc., and it is not even true of several to which it -is frequently applied, such as the razor, the penknife, etc. The action -can be said to be “saw-like” only when the teeth act as independent -wedges and remove a small portion of the substance acted upon, the -portion being known as _saw-dust_. Now in cutting sections of wood with -a sharp razor, where but a single stroke is used to carry the cutting -edge across a section, say half an inch in diameter, the edge of the -razor does not act like a saw; none of the material is removed except -the section itself; in other words, there is no saw-dust. That the edge -of the knife or razor is not even, is very easily proved by means of the -microscope, but it will be found that the notches and projections form a -series of lancet-shaped knifelets, each one of which acts just as does -the blade of a penknife when drawn over a piece of wood or a quire of -paper. Now if we lay a quire of paper on a board and draw the edge of a -penknife over it, we will cut down through the paper, not by sawing but -by a moving wedge. It is precisely in this way that the little -lancet-shaped teeth on the edge of a razor act when the latter is used -to cut a section. - -If we further examine the edge of the razor, we will find that the -bottoms of the notches are comparatively blunt; if therefore we press -the razor directly forward we soon press these blunt portions of the -general edge against the material to be cut, and the resistance becomes -so great that the material is actually crushed or torn. This would not -happen if we had an absolutely perfect edge—one without any notches. -This being practically unattainable, however, we must endeavor to make -up for it by a sawing motion, (though not a sawing action) at the same -time seeking to avoid as much as possible those saw-like features which -render this motion necessary. We have dwelt at length upon this point -because so much has been written comparing the edge of a razor to that -of a saw, that some persons actually advise us to give the edges of our -knives and razors a saw-like character, under the impression that by so -doing they will work better. This is a fallacy; the best work will be -obtained from the smoothest and most perfect edge, provided the latter -is thin enough. - -If the material of which our cutting instruments are made would allow -it, that is to say if it was perfectly hard, perfectly rigid and -incapable of being crushed or torn apart, the proper shape of a cutting -instrument would be a wedge of the most acute form possible. But since -the steel which we use is limited in its hardness and its power of -resisting crushing and bending influences, the blades of our knives must -have a certain strength or thickness, depending upon the character of -the material to be cut. For very hard substances the knife must be stout -and the edge ground to a comparatively obtuse angle; for moderately soft -substances, such as wood, the angle may be more acute, while for very -soft tissues the thinnest blade and the sharpest edge are most suitable. - - - [Illustration: Fig. 1.] - - -The various angles to which cutting tools of different kinds are ground -are shown in the accompanying illustrations, which explain themselves. - - - [Illustration: Fig. 2.] - - -In the diagrams just given, the sides of the wedge are carried in -straight lines to the very edge. In practice, however, this is never -done, there being two strong objections to such a form. In the first -place if the sides were as shown in the figures, every time the tool was -ground or set, the entire side would have to be ground off, and this -would involve great labor. But another difficulty, quite as great, would -occur in the use of the instrument, for since the wedge keeps growing -constantly and proportionately thicker, the friction between the sides -of the wedge and the material would rapidly become very great. Therefore -most cutting edges are ground to a second angle, much more obtuse than -the first, and it is this second angle which forms the true cutting -edge. And it is obvious that the mass of material required to carry out -the ultimate angle in any case is wholly unnecessary, for if the tool be -strong enough at _a b_ (Fig. 2) it will certainly be strong enough at _c -d_. An extreme illustration of this principle is shown in the cold -chisel used for cutting iron, the edge of which is shown in Fig. 2, and -the angle of 80° to which it is ground is carried out by dotted lines. -The angle which the sides of the chisel (not the sides of the extreme -cutting edge however) make with each other is 25°. - - - [Illustration: Fig. 3.] - - - [Illustration: Fig. 4.] - - -There are two methods by which this change of angle may be made, one of -which is shown in the cold chisel just figured, and the other in the -razor of which a section is shown in figures 3 and 4. In the case of the -cold chisel it will be seen that the tool is first formed to a thin -straight wedge which is afterwards changed to one that is much more -blunt. This answers very well where the ultimate angle is comparatively -large or blunt, as is the case with penknives, table-knives, -carving-knives, etc. But where the ultimate angle is very small this -plan does not answer well, and the method shown in Fig. 3 is generally -adopted. Here the ultimate angle is such that lines touching the extreme -edge and the back of the blade are perfectly straight and form the -actual cutting angle. In this case, therefore, the relief is obtained by -hollowing out the sides of the blade, and this is done to various -extents, the extremes being shown in figures 3 and 4. Fig. 3 shows a -section of a razor ground on a stone 12 inches in diameter, which is as -large as is generally used for this purpose. Fig. 4 is a section of a -razor ground on a four-inch stone—the smallest in general use. This -method of changing the angle is of course substantially the same as the -first, merely differing in the mechanical device used, but it affords -this important advantage that in the subsequent honing and stropping -processes the back of the razor forms a perfect guide by which the -ultimate angle may be determined. This is not the case with the cold -chisel or the carving-knife, in both of which cases the eye and hand -alone determine the cutting angle, which is therefore apt to become -irregular or even rounded—the worst form of all. This will be more -easily understood from the following engravings where A, Fig. 5, shows a -penknife blade, as applied to an oilstone for the purpose of giving it -the final edge. The angle here shown is considerably greater than that -generally used, but the principle is the same. It is evident that if, in -moving the blade back and forth on the stone we allow it to rock or -change the angle which the blade makes with the stone’s surface, the -edge will become rounded as shown in Fig. 6—a form which for delicate -work is useless. - -If the blade be laid down flat as at B, Fig. 5, the labor of wearing -away the superfluous metal will be enormous. But if the blade be hollow -as Fig. 7, (where the hollow is, for clearness of illustration, slightly -exaggerated) then the ultimate angle may be formed quickly and -accurately, there being no danger of the angles being changed on account -of want of skill on the part of the operator. - - - [Illustration: Fig. 5.] - - - [Illustration: Fig. 6.] - - - [Illustration: Fig. 7.] - - - [Illustration: Fig. 8.] - - -In some cases one side is left quite flat and the other side is ground -to two or sometimes three angles, as in the carpenter’s chisel, a -section of which is shown in Fig. 8, where _a a_ shows the angle made by -the body of the blade; _b b_ the angle of the bevel formed by the -grindstone, and _c c_ the angle of the cutting edge which is formed by -the oilstone. In this case the flat side A B forms a straight guide and -enables the workman, in cutting, to make straight, clean work. In -sharpening such a tool on the oilstone the flat side is always laid flat -on the oilstone and merely smoothed off,[19] and the skill of the -workman is chiefly shown in the accuracy with which he forms the angle -_c_ B _c_. The dexterity with which skilled workmen can effect this by -the hand alone is astonishing, but in the hands of those who have had -but little practice the edge infallibly becomes rounded as shown in Fig. -6. Therefore wherever a knife with a flat side is used, no attempt -should ever be made to grind this flat side on the hone. Such an attempt -will almost always result in an edge so irregular that it will be almost -impossible to cut a good section with it. But if the under side of the -knife be left truly flat, we will have the very best tool that can be -had for use with the microtome. Unfortunately, however, it is very -difficult to get a knife with a truly flat surface, that is, one that is -perfectly “out of wind” as mechanics say. As a general rule the flat -sides of knives are not true planes but irregularly curved surfaces; -consequently when laid on a plane surface, such as the table of a -microtome, they rock, and the edge is in contact with the table at some -points and separated from it at others, and the points which are in -contact change as the knife is moved diagonally across the table. This -makes the section irregular and worthless. But a really good knife with -a perfectly true flat side is such a valuable tool that a good deal of -effort may be profitably expended in getting it, and when once obtained -never let the flat side be touched by a grindstone, or more than touched -by a hone. It is not absolutely necessary, however, that the sides of a -delicate knife should be curved, provided the knife is used for cutting -very soft materials. An angle of 10° or even 5° gives a pretty stout -blade when carried back three-quarters of an inch, as may be seen by -examining Fig. 1, and the guiding action of the very thick back may be -obtained by means of an artificial guide, applied like the brass backs -of tenon saws. Such an arrangement is shown in Fig. 9, and has been -found very effectual. - -Footnote 19: - - Holtzapffel tell us that chisels that are required for paring across - the end grain of moderately soft wood are considered to hang better to - the work when they have a very slight keen burr or wire edge thrown up - on the face or flat side of the tool. But this does not apply to - section knives. - -When the knife is to be honed, the back is applied and fastened by means -of two or three set screws. When laid on the hone, the edge of the knife -and the lower surface of the back form the guide and regulate the -cutting angle. In this way we can use a broad, thin blade and yet secure -great accuracy in honing it. Such a blade has this advantage also, that -it is not so liable to be rounded and thus injured by stropping as one -in which the relief is obtained by hollowing out the sides. - - - [Illustration: Fig. 9.] - - -Such, then, are the general principles which govern the construction of -cutting tools, including the section knives used by microscopists. We -will now give a few practical directions for selecting a knife and -putting and keeping it in order. - -In selecting a knife for cutting sections, regard must be had to the -texture of the material that is to be cut. To attempt to cut delicate -sections of soft tissues with the stout knives which are suitable for -cutting sections of woody fibre would be to destroy the sections, while -to reverse the operation and cut sections of wood with thin, delicate -knives would result in the ruin of the knife. We have seen a most -excellent knife seriously injured by an attempt to cut material that was -too hard for it. The knife was very thin, and had proved most excellent -in cutting sections of such material as kidney, liver, etc. An attempt -was made, against our protest, to cut a section of an apple-shoot, the -wood of which was mature. Before the knife had gone half way across, it -bent, dug into the wood and broke, leaving an ugly gap in the middle. -Experienced section-cutters know this very well, but young microscopists -are not so familiar with the facts just stated, and the point is too -important to be overlooked. Those, therefore, who devote themselves to -microscopical studies, or who expect to make sections of materials of -several kinds, differing in hardness, etc., must provide themselves with -knives of different degrees of strength. - -For common work, good razors are as good as anything, provided they can -be obtained with straight edges. Where razors are not suitable, recourse -must be had to the surgical instrument maker, though we are sorry to say -that there are but few in this country that know how to forge, temper -and grind a decent knife. Most of our dealers in instruments do not make -the instruments they sell; they import the goods they sell with their -names stamped on, and thus get a reputation as manufacturers; a special -order they are unable to fill respectably. There are some exceptions, -but of the majority of dealers what we have written above is true. - -The points which specially demand attention in a knife for cutting -sections are these: 1. Quality of the steel used; 2. Temper; 3. Form of -the blade. - -Of the quality of the material of which a knife is made, nothing can be -determined except by actual trial. The old tests of staining with acids, -examining with the microscope, etc., are worthless, or at least too -crude and uncertain to be of any practical value. Color changes with the -degree of polish that is produced, and, in short, there is no reliable -guide. The purchaser must depend entirely upon the reputation of the -manufacturer. There is plenty of good steel to be found; the trouble -lies with the cutlers. They are careless and in haste, and as a -consequence they burn the steel or fail to work it sufficiently, and the -result is a useless tool. - -The steel may be of the very best quality, however, and well forged, and -yet the knife may fail from being badly tempered—too soft or too hard. -If too soft, the edge is soon dulled; the knife requires to be -frequently honed, and the time wasted in keeping it in order is a -serious drawback. If too hard, it is impossible to give it a keen edge, -for the metal crumbles away as soon as it is honed or stropped very -thin, and the edge becomes ragged and dull. Good steel, well forged, may -be so tempered that it will neither crumble nor become rapidly dull. - -Much may be learned on this point from careful inspection of the edge, -and trial on a piece of horn, such as an old razor handle. When drawn -over a clean piece of horn once or twice the edge of a soft knife is -completely dulled; if well-tempered it should scarcely lose its -keenness. Again, when laid flat on the thumb nail and pressed, the edge -ought to bend up without breaking or crumbling, and at once, when the -pressure is removed, resume its original shape. The extent to which -extreme hardness and durability, or toughness, may be combined, is well -shown in the famous Toledo sword-blades. One of these blades will shear -through an iron nail without having its edge perceptibly dulled, and yet -so tough and springy is it that it may be coiled up into a hoop of -several folds without breaking or receiving any permanent set. If we -could only get section knives of stuff like this, it would be a pleasure -to work with them. - -After all, however, the only test of these two points, material and -temper, is a fair trial in actual practice. Of the form of the blade, -however, it is easy to judge, and there are a few points which are -frequently overlooked and which give rise to errors that are attributed -to other causes. - -In the text we are told that “It is essentially necessary that the back -and edge of the blade be strictly parallel to each other.” The author -undoubtedly knew what the correct form should be, but the definition he -has given is not a correct mathematical statement of the conditions -involved. These are as follows: - -_The edge must form a straight line, and both the edge and the under -side of the back must lie in the same plane._ - -Let us consider these conditions somewhat carefully. - -Since the hole in which the material to be cut is imbedded, is always -circular, and since the blade is generally pressed forcibly against the -table of the microtome, it is obvious that if the edge of the knife be -curved it will sink into the hole to a greater or less depth according -as it is further from the centre of the hole or nearer to it. To explain -this let us refer to the greatly exaggerated drawing given in figure 10 -where the edge of the knife, _a_, _b_, is shown in two different -positions covering the hole of the microtome. The least degree of -reflection will show that as the knife passes towards the centre from _a -b_ to _aʹ bʹ_, it will have a tendency to turn on the back as on a -hinge, and the middle of the edge will sink deeper into the hole as it -approaches the centre of the latter. The section will therefore vary in -thickness and prove useless. This difficulty can be obviated only by the -use of a straight edge like _e f_, which will always lie in the same -plane. - - - [Illustration: Fig. 10.] - - -If the knife were perfectly rigid, and the curved edge and back lay -entirely in the same plane, this difficulty would not occur to any great -extent. But since a curved edge rarely lies wholly in the plane of the -back of the knife, and since the blades of most knives, especially those -thin ones used for cutting sections of soft tissues, yield a little to -pressure, and since this pressure is never exactly the same, it is -impossible to prevent irregularities from occurring. - -While it is not necessary that the back of the knife and the cutting -edge should be parallel to each other, it is absolutely necessary that -they be in the same plane, or, as mechanics say,—“out of wind.” If this -condition be not observed, the blade will rock on the microtome table as -it passes over it, and irregularity in thickness of section will result. - -A slight knowledge of geometry will enable any one to see that these -statements are strictly accurate. - -As regards other points in the form of the knife, we refer to what has -been previously said when discussing the general principles which should -govern the construction of cutting tools. - -We now proceed to give a few practical directions for sharpening knives -and razors and keeping them in order. - -Section knives, during the process of sharpening, are subjected to three -distinct processes: 1, Grinding; 2, Honing; 3, Stropping. - -Grinding is one of the most important, though it is probable that it -will rarely be undertaken by the microscopist himself. More knives and -razors are spoiled in grinding than in any other way. We have now in our -possession an excellent knife, which in an evil hour we entrusted to a -New York cutler, and received it back utterly ruined, the temper being -entirely taken out of the blades! Some of our readers may wonder at -this, but unfortunately it is too true. The cutler, to save time and -trouble, too frequently holds the blade against the stone with such -force that it becomes over-heated, especially when he is a little -careless and allows the supply of water to fall short.[20] The owner -does not find this out until he discovers that the knife is ruined, -because nothing is more easy than to cool the blade and grind off the -tell-tale blue spots. When charged with his rascality, the cutler always -denies it and lays the blame on a “soft spot in the steel”—a miserable -subterfuge—too transparent to deceive the least experienced. - -Footnote 20: - - Nothing is more easy than to heat a thin rod or stout wire red hot by - holding it against a dry grindstone rapidly revolving. We have often - kindled fire in this way. - -The only protection against this is either to entrust the knife to a man -of known carefulness and integrity, or to stand over him while he does -it. If the knife be ground under the owner’s eye, no fear need be -entertained, because it is easy to insist upon the use of plenty of -water. - -The grindstone used for section knives should be of fine grain, and it -should run true and be very straight across the face, otherwise it will -be impossible to grind the knife true, and this, as we have seen, is a -necessity. - -Every microscopist that expects to do much at cutting sections must -learn to hone his own knife or razor. Of the various hones in use the -famous Turkey oilstone is said to be altogether the best. It is, -however, very difficult to get it genuine and in sufficiently large -pieces. We therefore use the German hone-slate, a softer, yellow stone -of wonderful fineness and cutting power. The ordinary whetstones are -altogether too coarse, and as for artificial stones and strops, they may -do for coarse work and common razors for _scraping_, but they will not -do for knives used for section-cutting. If any of our readers should be -so fortunate as to possess a good, old-fashioned Turkey oilstone with a -fair sized surface, let them think much of it. It is invaluable. Years -ago, when working on some investigations that required the use of very -sharp knives, we were offered, by an old English carpenter, the use of a -real Turkey stone. We have never since found anything that did its work -so quickly and so well. - -To merely mention the substitutes for Turkey oilstone would fill some -pages. We therefore confine ourselves to the German hone. It is obtained -from the slate mountains in the neighborhood of Ratisbon, where it -occurs in the form of a yellow vein running vertically into the blue -slate, sometimes not more than an inch in thickness, and varying to -twelve to eighteen inches. After being quarried it is sawed into thin -slabs, which are usually cemented to a similar slab of the blue slate as -a support, and the combined stones are then set in a wooden frame and -fitted with a cover, also of wood. Unlike the Turkey oilstone, the -Arkansas stone, and some others, the German hone is soft and easily -scratched and worn. It must therefore be carefully preserved, and as the -_flatness_ of the hone is an important point, it should never be used -for anything but section knives. - -Having purchased a hone, the first thing to do is to see that it is -perfectly true; that is, that its surface is a perfect plane. If hollow -or twisted, it is useless until made straight. It may be tested by means -of two steel or wood straight-edges, and the method of doing this, which -is very simple but difficult to describe, the microscopist can learn -from any cabinet maker or carpenter. If the hone be not true it must be -made so, and this is best done by grinding it with emery on a slab of -marble or, better still, a plate of cast iron which has been planed -true. (Waste castings with planed surfaces may be found in most machine -shops, and may be either borrowed or purchased for a small sum.) If the -hone is very uneven, coarse emery may be used at first; then finer must -be taken, and so on until the surface of the hone is not only true but -very smooth. This involves considerable labor, but it cannot be avoided -if a _true_ edge as well as a sharp one is desired, and hence our advice -to use the hone for nothing but section knives. Accuracy in a penknife -or a razor for shaving is of no consequence; in a section-knife it is a -_sine qua non_. - -The surface of the hone must not only be true and smooth, it must also -be clean and free from dust and grit, a single particle of which may -spoil the work of hours. It should therefore, when not in use, be kept -constantly covered. It is always used with oil, and this oil should be -of a kind that does not readily dry up. Good sperm is excellent, and so -is purified neat’s-foot oil. Avoid kerosene, soap and water, and similar -fluids, which are so frequently recommended, especially under the guise -of new discoveries. They have all been tried and found wanting. After -use, the stone should be carefully wiped clean, fresh oil being applied -when it is next used. It must never be used without a liberal supply of -oil, otherwise it will become glazed and will no longer act on the -steel. - -The hone being in good order, the blade is laid flat on it and moved -over its surface with circular sweeps. The method of doing this is -easily acquired, and is best learned by watching an expert cutler at -work. If we could only hit it, the perfection of this operation would be -to wear down the sides of the blade until they just met; they would then -form a keen and perfect edge. Unfortunately we cannot always hit this -point exactly; we are apt to overdo the matter just a little, and then -comes up the _bête noir_ of beginners—the “wire edge.” This is caused by -the metal of the blade bending away from the hone as soon as it becomes -of a certain degree of thinness. Once it does this it cannot be worn off -by the hone, and the only way to remove it is to draw the edge of the -knife or razor across a piece of horn or hard wood. After removing the -wire edge in this way, give the blade one or two sweeps on the hone and -then strop it. If the blade be very soft, the wire edge comes very -quickly and easily, and is very hard to get rid of. On very hard blades -the wire edge is not so apt to make its appearance. It comes, however, -on very excellent blades. It may be avoided in a measure by driving the -blade edge-first over the hone, and indeed the blade should always be -sharpened most in this way. And since the backward and forward strokes -are always nearly equal, as regards space passed over, this is -accomplished by exerting a greater pressure on the forward than on the -backward stroke. - -This wire edge is a nasty thing when it breaks off on the hone. Unless -removed it will very speedily ruin a fine knife, therefore look out for -it and wipe off the hone carefully if you have any suspicion that -particles of steel have broken off the blade and got on to it. - -In honing, as in everything else, however, nothing but practice will -impart skill, and he who intends to become an expert should practice on -a few old razors, grinding, honing and stropping them himself, until he -has acquired the art of giving them an edge far keener than most of the -razors ordinarily used for shaving. - -The last operation to which the knife is subjected is that of stropping, -and as the blade should be stropped after every section, it becomes -important that our tools should be good and that we should know how to -use them. By having two or three knives we can always avoid grinding and -honing the blades ourselves, for it is then easy to hire the work done, -and half a dozen knives will last a careful worker a long time with -merely the aid of a good strop. But the strop he must use himself. -Fortunately no great skill is required in stropping, but the strop must -be a good one and is best home-made. - -Our readers have doubtless seen the “Cheap John” strop-vendors take a -rough table knife, strop it on one of their “patent” strops and cut a -hair with it. Nevertheless such a knife, sharpened in that way, would -not cut good sections, and such a strop is not just the thing for giving -the finishing touch to a section-knife, even though the label does say -that it is “intended for surgical instruments.”[21] - -Footnote 21: - - The finest emery paper, glued on a strip of wood and used as a strop, - will impart to a razor an edge sufficiently keen to enable it to - remove the beard, and if paper three or four degrees coarser be used, - a very dull knife or razor may be sharpened, and afterwards stropped - on the finer emery until it is keen enough to cut a hair. But it will - be found that cutting edges produced in this way are not smooth enough - for section-cutting. - -The strop should never be used with the intention of removing metal so -as to thin the edge of the knife. This is the proper function of the -hone, and those who depend most on the hone and least on the strop, will -always succeed best. The strop is used in the first place for -_smoothing_ off the edge, and in the second for removing that incipient -dullness which always comes from even the slightest use. It is true that -in the latter case the strop trespasses somewhat on the functions of the -hone, but only to a very slight extent, and stropping should never be -carried so far as to require more than a very few strokes. - - - [Illustration: Fig. 11.] - - - [Illustration: Fig. 12.] - - -The best material for a strop is good calf-skin, well tanned, and firmly -glued to a strip of wood with the hair side out. The leather should be -hard, otherwise it will rapidly round the edge of the knife. The way in -which this occurs is readily understood from figures 11 and 12. In Fig. -12 the leather is seen to rise up behind the edge of the blade as the -latter passes over it, so that instead of two plane facets meeting at an -angle of from 15° to 20° as left from the hone, (Fig. 12) the edge has -become considerably rounded and the ultimate angle of the cutting edge -is nearly or quite doubled. The hardest and firmest leather should -therefore be chosen, avoiding of course any leather that has been made -hard and unpliable by the action of water or other agents. Two sides -will be found enough for a strop. On one the leather should be kept -clean, while the other should be thoroughly impregnated with fine -grained, but very hard rouge or crocus.[22] Rouge is an artificial oxide -of iron prepared by exposing sulphate of iron to heat. The hardness of -the resulting powder depends upon the temperature to which it has been -exposed, and this temperature is very well indicated by the color which -the rouge assumes. Bright red or crimson rouge is soft and will not cut -steel; hard rouge, suitable for polishing steel, is purple in color, and -this quality should therefore be chosen. Great care should be taken to -see that it is free from gritty particles, and it should be well rubbed -into the leather in a dry state. All mixtures of grease and oil with -abrasive substances should be eschewed. If the leather be of good -texture and the rouge hard and fine, a very few strokes will suffice to -impart the last degree of smoothness and keenness to the blade. - -Footnote 22: - - Rouge may be purchased from dealers in watch-makers’ tools. Those who - cannot procure it readily may very easily prepare it for themselves. - Full directions may be found in the “Amateur’s Handbook.” New York: - Industrial Publication Company. - -Since grit and dust would soon spoil the strop, it should be kept -carefully covered and protected. The rouge will require occasional -renewing, which may be done by sprinkling a little lightly over the -surface and rubbing it in with the finger. Consequently we find that the -best and most convenient holder for rouge is a bottle with some fine but -porous fabric tied over the mouth of it, forming as it were a sort of -dredge. Over the bottle mouth and its cover should be tied a paper cap -to keep out dust. - -We have thus endeavored to give, in as simple a manner as possible, such -information as will guide the microscopist to the acquisition of skill -in this most important but generally despised department of his art. We -are told by the biographer of Swammerdam that a great deal of his -success was to be attributed to his skill in sharpening his fine knives -and scissors. The same is also stated of other noted workers, and yet -none give even the slightest directions to the novice who desires to -follow in their footsteps. There is not to our knowledge a single book -in the English language which treats fully of this subject, with perhaps -the exception of Holtzapffel’s work on “Mechanical Manipulation,” and -this has long been out of print. As previously stated, however, it is -only by practice that the necessary finger-skill can be acquired, but -this skill is well worth acquiring at any cost. The man who depends upon -cutlers and knife grinders will never make satisfactory progress. - - NOTE H. - -We are inclined to believe that the difficulty of enclosing glycerine -does not arise from the dissolving action of this liquid, so much as -from the great adhesiveness which exists between it and glass. Oily -cements are of course attacked by glycerine, but shellac and several -other gums are insoluble, and drying oils, if well oxidized are also -insoluble. Where cells are used they must be first firmly attached to -the clean slide, and the cement should also be brought into direct -contact with the clean cover. Glycerine does not evaporate at ordinary -temperatures, and consequently wherever the slide or cover is soiled -with it, no cement will ever adhere until the glycerine has been wiped -off. There is no prospect of its drying. - - NOTE I. Page 48. - -The solution here referred to, and which is known as Kleinenberg’s -solution, is made in the following way: - -(1.) Make a saturated solution of crystallized calcium chloride in 70 -per cent. alcohol, and add alum to saturation. (2.) Make also a -saturated solution of alum in 70 per cent. alcohol. Add (1) to (2) in -the proportion of 1:8. To the mixture add a few drops of a saturated -solution of hæmatoxylin in absolute alcohol. - -This solution may be used in very many cases for staining sections, in -place of the ordinary watery solution of logwood alum. It may, if -required, be diluted with the mixture of 1 and 2. The stained sections -are placed at once in strong spirit. - ------------------------------------------------------------------------- - - - - - INDEX. - - Acetic acid, 38 - Adipose tissue, 63 - Æther microtome, 24 - Air-bubbles, 40, 55, 62 - Alcohol, 17, 19 - absolute, 54 - - Balsam, Canada, 46, 51 - to clean from slide, 55 - Beale’s carmine fluid, 33 - Bell’s cement, 41 - Blue staining fluid, 60 - Bone, 16, 57 - decalcified, 58 - Bottles for media, &c., 48 - Brain, 59 - Brunswick black, 41 - - Capillary attraction, 55 - Carmine staining, 32 - Carpenter, Dr., 37, 41 - Cartilage, 60 - Cells, to make, 59 - Centring slide, 38 - Chloroform-balsam, 51, 54 - Chromic acid, 17 - Clove oil, 51, 54 - Coffee berry, 62 - Cover, applying, 37 - German plan, 39 - Crochet-needle holders, 39 - - Double staining, 73 - Dry mounting, 58, 65, 72 - - Fat, 63 - Finishing slide, 54 - Fibro-cartilage, 62 - Freezing method, 42-47 - Fresh tissues, to cut, 15-17 - Fruit stones, 58 - - Gardner, Mr., 25, 31 - Gelatine cement, 41 - Glycerine, 37, 38 - Gold staining, 58 - Gum, imbedding in, 22, 66 - strong, 43 - weak, 31, 71 - - Hair, 63-69 - Hæmatoxylon, _see_ Logwood - Hand-sections, 19 - Hardening agents, 19 - Hoggan, F. Elizabeth, Dr., 61 - Hone, 26, 57 - Horn, hoofs, &c., 16, 64 - Hyaline cartilage, 62 - - Ice, for freezing, 43 - Injections, to harden, 19 - Ink staining, 70 - Intestine, 42, 43, 64 - Iron staining, 61 - - Kay, J. A., Mr., 52 - Kidney, 17 - Klein’s _lifter_, 35 - Knife, section, 25, 30 - - Leaves, &c., to cut, 12 - Ligaments, intervertebral, 62 - Lime, carbonate of, 37 - Liver, 65 - Logwood staining, 47 - Lung, 43, 65 - - Martindale’s logwood fluid, 47 - Media, mounting, 38 - Methylated spirit, _see_ Alcohol - Microtome, 21 - choice of, 22 - Microtome, employment of, 29 - freezing, 43, 44 - imperfection in, 23, 46 - Rutherford’s, 31 - Muscle, 66 - - Needles, microscopical, 39 - - Orange-peel, 67 - Ovary, 67 - - Papillæ of finger, 69 - Paraffine, adhering to sections, 27 - imbedding in, 20, 26 - mixture, 26 - _rising_ in tube, 23 - shrinks in cooling, 29 - Paul, Dr., 70 - Pathological specimens, 19, 62 - Picro-carmine, 59, 68, 72 - Porcupine quill, 67 - Potato, 67 - Preparation of animal tissues, 16 - vegetable tissues, 15 - Prussian blue pigment, 38 - - Rangoon oil, 14, 47 - Razors, 20, 26, 29, 30 - Rush, 78 - Rutherford’s microtome, 24, 31 - “Practical Histology,” 43 - - Salicylic acid, 44 - Salt, for freezing, 45 - Schäfer’s “lifter,” 35 - “Practical Histology,” 48 - Scissors, section, 13 - Sebaceous glands, 69 - Section-cutter, _see_ Microtome - Section-knife, 24 - Sections, thickness of, 31 - to dehydrate, 52 - to transfer, 33 - Seeds, 63 - Skin, 68 - Sperm oil, 44 - Spinal cord, 69 - Spirit lamp for balsam, 53 - weak, 36, 59 - Sponge, 71 - Spoon, section, 35, 54 - Staining agents, 31 - Strop, razor, 26, 29 - Stomach, 71 - Sudoriferous glands, 69 - - Taste-bulbs, 71 - Teeth, 16, 58 - Tongue, 71 - Tubes, collapsible, 56 - - Valentin’s knife, 14 - Vegetable ivory, 72 - tissues, to prepare, 12 - Vessels, porcelain, 33 - - Water-bath, cheap, 29 - Whalebone, 64 - White zinc cement, 56 - Wood, 72 - ------------------------------------------------------------------------- - - =CATALOGUE= - - OF - - Books and Periodicals - - PUBLISHED AND FOR SALE BY - - THE INDUSTRIAL PUBLICATION COMPANY, - - _176 Broadway, New York_. - -👉 _Any of these Books may be obtained from any Bookseller or Newsdealer, -or will be sent Free by mail to any part of the United States or Canada -ON RECEIPT OF PRICE._ - ------------------------------------------------------------------------- - -=The Amateur’s Handbook of Practical Information,= - - For the Workshop and the Laboratory. Second Edition. Greatly - Enlarged. Neatly Bound 15 cents. - -This is a handy little book, containing just the information needed by -Amateurs in the Workshop and Laboratory. Directions for making Alloys, -Fusible Metals, Cements, Glues, etc.; and for Soldering, Brazing, -Lacquering, Bronzing, Staining and Polishing Wood, Tempering Tools, -Cutting and Working Glass, Varnishing, Silvering, Gilding, Preparing -Skins, etc., etc. - -The New Edition contains extended directions for preparing Polishing -Powders, Freezing Mixtures, Colored Lights for tableaux, Solutions for -rendering ladies’ dresses incombustible, etc. There has also been added -a very large number of new and valuable receipts. - ------------------------------------------------------------------------- - -=Rhymes of Science: Wise and Otherwise.= - - By O. W. Holmes, Bret Hart, Ingoldsby, Prof. Forbes, Prof. J. W. - McQ. Rankine, Hon. R. W. Raymond, and others. - - With Illustrations. Cloth, Gilt Title. 50 cents. - ------------------------------------------------------------------------- - -=Section-Cutting.= - - A Practical Guide to the Preparation and Mounting of Sections for - the Microscope; Special Prominence being given to the Subject of - Animal Sections. By Sylvester Marsh. Reprinted from the London - edition. With Illustrations. 12mo., Cloth, Gilt Title. 75 cents. - -This is undoubtedly the most thorough treatise extant upon -section-cutting in all its details. The American edition has been -greatly enlarged by valuable explanatory notes, and also by extended -directions, illustrated with engravings, for selecting and sharpening -knives and razors. - ------------------------------------------------------------------------- - -=Companion for Cheap Microscopes.= - - Intended for those who have absolutely no knowledge of the - Microscope or how to use it. Price, in Boards, 30 cents. In Cloth, - Gilt Title 50 cents. - -This is a very elementary book, giving very simple directions for using -the Microscope, and for collecting, preparing and mounting objects. - ------------------------------------------------------------------------- - -=How to Use the Microscope.= - - A Simple and Practical Book, intended for beginners. By John Phin, - editor of “The American Journal of Microscopy.” Second Edition. - Greatly Enlarged, with 50 illustrations in the text and 4 full-page - engravings printed on heavy tint paper. 12mo., Neatly bound in - Cloth, Gilt Title. 75 cents. - ------------------------------------------------------------------------- - -=The Microscope.= - - By Andrew Ross. Fully Illustrated. 12mo., Cloth, Gilt Title. 75 - cents. - -This is the celebrated article contributed by Andrew Ross to the “Penny -Cyclopædia,” and quoted so frequently by writers on the Microscope. -Carpenter and Hogg, in the last editions of their works on the -Microscope, and Brooke, in his treatise on Natural Philosophy, all refer -to this article as the best source for full and clear information in -regard to the principles upon which the modern achromatic Microscope is -constructed. It should be in the library of every person to whom the -Microscope is more than a toy. It is written in simple language, free -from abstruse technicalities. - ------------------------------------------------------------------------- - -=Diatoms.= - - Practical Directions for Collecting, Preserving, Transporting, - Preparing and Mounting Diatoms. By Prof. A. Mead Edwards, M. D., - Prof. Christopher Johnston, M. D., Prof. Hamilton L. Smith, LL. D. - - 12mo., Cloth. 75 cents. - -This volume undoubtedly contains the most complete series of directions -for Collecting, Preparing and Mounting Diatoms ever published. The -directions given are the latest and best. - ------------------------------------------------------------------------- - -=Common Objects for the Microscope.= - - By Rev. J. G. Wood. Upwards of four hundred illustrations, including - twelve colored plates by Tuffen West. - - Illuminated Covers. 50 cents. - -This book contains a very complete description of the objects ordinarily -met with, and as the plates are very good, and almost every object is -figured, it is a most valuable assistant to the young microscopist. - ------------------------------------------------------------------------- - -=Five Hundred and Seven Mechanical Movements.= - - Embracing all those which are Most Important in Dynamics, - Hydraulics, Hydrostatics, Pneumatics, Steam Engines, Mill and Other - Gearing, Presses, Horology and Miscellaneous Machinery; and - including Many Movements never before published, and several of - which have only recently come into use. By Henry T. Brown, editor of - the “American Artisan.” Eleventh Edition. $1.00. - -This work is a perfect Cyclopædia of Mechanical Inventions, which are -here reduced to first principles, and classified so as to be readily -available. Every mechanic that hopes to be more workman, ought to have a -copy. - ------------------------------------------------------------------------- - -=The Six Days of Creation.= - - The Chemical History of the Six Days of Creation. By John Phin, C. - E., editor of “The American Journal of Microscopy.” 12mo., Cloth. 75 - cents. - ------------------------------------------------------------------------- - -=Stories About Horses.= - - Just the Book for Boys. With eight full-page engravings. In Boards, - 25 cents. In Cloth 50 cents. - ------------------------------------------------------------------------- - -=Shooting on the Wing.= - - Plain Directions for Acquiring the Art of Shooting on the Wing. With - Useful Hints concerning all that relates to Guns and Shooting, and - particularly in regard to the art of Loading so as to Kill. To which - has been added several Valuable and hitherto Secret Recipes, of - Great Practical Importance to the Sportsman. By an Old Gamekeeper. - - 12mo., Cloth, Gilt Title. 75 cents. - ------------------------------------------------------------------------- - -=The Pistol as a Weapon of Defence,= - - In the House and on the Road. - - 12mo., Cloth. 50 cents. - -This work aims to instruct the peaceable and law-abiding citizens in the -best means of protecting themselves from the attacks of the brutal and -the lawless, and is the only practical book published on this subject. -Its contents are as follows: The Pistol as a Weapon of Defence.—The -Carrying of Fire-Arms.—Different kinds of Pistols in Market; How to -Choose a Pistol.—Ammunition, different kinds; Powder, Caps, Bullets, -Copper Cartridges, etc.—Best form of Bullet.—How to Load.—Best Charge -for Pistols.—How to regulate the Charge.—Care of the Pistol; how to -Clean it.—How to Handle and Carry the Pistol.—How to Learn to -Shoot.—Practical use of the Pistol; how to Protect yourself and how to -Disable your antagonist. - ------------------------------------------------------------------------- - -=Lightning Rods.= - - Plain Directions for the Construction and Erection of Lightning - Rods. By John Phin, C. E., editor of “The Young Scientist,” author - of “Chemical History of the Six Days of the Creation,” etc. Second - Edition. Enlarged and Fully Illustrated. - - 12mo., Cloth, Gilt Title. 50 cents. - -This is a simple and practical little work, intended to convey just such -information as will enable every property owner to decide whether or not -his buildings are thoroughly protected. It is not written in the -interest of any patent or particular article of manufacture, and by -following its directions, any ordinarily skilful mechanic can put up a -rod that will afford perfect protection, and that will not infringe any -patent. Every owner of a house or barn ought to procure a copy. - ------------------------------------------------------------------------- - -=Instruction in the Art of Wood Engraving.= - - A Manual of Instruction in the Art of Wood Engraving; with a - Description of the Necessary Tools and Apparatus, and Concise - Directions for their Use; Explanation of the Terms Used, and the - Methods Employed for Producing the Various Classes of Wood - Engravings. By S. E. Fuller. - -Fully illustrated with Engravings by the author, separate sheets of -engravings for transfer and practice being added. - -New Edition, Neatly Bound. 30 cents. - ------------------------------------------------------------------------- - -=What to Do in Case of Accident.= - - What to Do and How to Do It in Case of Accident. A Book for - Everybody. 12mo., Cloth, Gilt Title. 50 cents. - -This is one of the most useful books ever published. It tells exactly -what to do in case of accidents, such as Severe Cuts, Sprains, -Dislocations, Broken Bones, Burns with Fire, Scalds, Burns with -Corrosive Chemicals, Sunstroke, Suffocation by Foul Air, Hanging, -Drowning, Frost-Bite, Fainting, Stings, Bites, Starvation, Lightning, -Poisons, Accidents from Machinery, and from the Falling of Scaffolding, -Gunshot Wounds, etc., etc. It ought to be in every house, for young and -old are liable to accident, and the directions given in this book might -be the means of saving many a valuable life. - ------------------------------------------------------------------------- - - BOUND VOLUMES OF - - The Technologist, or Industrial Monthly. - -The eight volumes of THE TECHNOLOGIST, or INDUSTRIAL MONTHLY, which have -been issued, form a Mechanical and Architectural Encyclopædia of great -value; and, when properly bound, they form a most important addition to -any library. The splendid full-page engravings, printed on tinted paper, -in the highest style of the art, are universally conceded to be the -finest architectural and mechanical engravings ever published in this -country. We have on hand a few complete sets, which we offer for $16.00, -handsomely and uniformly bound in cloth. - -We have also a few extra sets of Vols. III to VIII inclusive. These six -volumes we offer for $8.00 bound in cloth. As there are but a very few -sets remaining, those who desire to secure them should order -immediately. - -NOTE.—The above prices do not include postage or express charges. The -set weighs altogether too much to be sent by mail. - ------------------------------------------------------------------------- - - - - -Just Published. 1 Vol., 12mo. Neatly Bound in Cloth, Gilt Title. Price -75 cents. - - HOW TO USE THE MICROSCOPE. - - A Simple and Practical Book, intended for beginners. - - BY JOHN PHIN, - - _Editor of “The American Journal of Microscopy.”_ - - Second Edition. Greatly Enlarged, with 50 illustrations in the text, - and 4 full-page engravings printed on heavy tint paper. - - CONTENTS: - -WHAT A MICROSCOPE IS.—Different Kinds of Microscopes.—Simple -Microscopes.—Hand Magnifiers.—The Coddington Lens.—The Stanhope -Lens.—Raspail’s Microscope.—The Excelsior Microscope.—Twenty-five cent -Microscopes and how to make them.—Penny Microscopes. - -COMPOUND MICROSCOPES.—Different kinds of Objectives.—Non-Achromatic -Objectives.—French Achromatic Objectives.—Objectives of the English -Form.—Immersion Objectives.—Focal Lengths corresponding to the numbers -employed by Nachet, Hartnack and Gundlach. - -HOW TO CHOOSE A MICROSCOPE.—Microscopes for Special Purposes.—Magnifying -Power required for different purposes.—How to judge of the quality of -the different parts of the Microscope. - -ACCESSORY APPARATUS.—Stage Forceps, Animalcule Cage, etc. - -ILLUMINATION.—Sun Light.—Artificial Light.—Bulls-Eye Condenser.—Side -Reflector.—The Lieberkuhn.—Axial Light.—Oblique Light.—Direct Light. - -HOW TO USE THE MICROSCOPE.—How to Care for the Microscope. - -HOW TO COLLECT OBJECTS.—Where to find Objects.—What to Look for.—How to -Capture Them.—Nets.—Bottle-Holders.—Spoons.—New Form of Collecting -Bottle.—Aquaria for Microscopic Objects.—Dipping Tubes. - -THE PREPARATION AND EXAMINATION OF OBJECTS.—Cutting Thin Sections -of Soft Substances.—Sections of Wood and Bone.—Improved -Section-Cutter.—Sections of Rock.—Knives.—Scissors.—Needles.—Dissecting -Pans and Dishes.—Dissecting Microscopes.—Separation of Deposits from -Liquids.—Preparing whole Insects.—Feet, Eyes, Tongues, Wings, etc., -of Insects.—Use of Chemical Tests.—Liquids for Moistening -Objects.—Refractive Power of Liquids.—Covers for Keeping out -Dust.—Errors in Microscopical Observations. - -PRESERVATION OF OBJECTS.—General Principles.—Recipes for Preservative -Fluids.—General Rules for Applying them. - -MOUNTING OBJECTS.—Apparatus and Materials for: Slides, Covers, Cells, -Turn-Table, Cards for Making Cells, Hot-Plate, Lamps, Retort Stand, -Slide-Holder, Mounting Needles, Cover Forceps, Simple Form of Spring -Clip, Centering Cards, Gold-Size, Black Japan, Brunswick Black, Shellac, -Bell’s Cement, Sealing Wax Varnish, Colored Shellac, Damar Cement, -Marine Glue, Liquid Glue, Dextrine.—Mounting Transparent Objects -Dry.—Mounting in Balsam.—Mounting in Liquids.—Mounting of Whole -Insects.—How to Get Rid of Air-Bubbles.—Mounting Opaque Objects. - -FINISHING THE SLIDES. - - May be obtained from any Bookseller or News Agent, or will be sent by - mail, postage paid, on receipt of price. - - THE INDUSTRIAL PUBLICATION COMPANY, - - P. 0. Box 4875. 176 Broadway, New York. - ------------------------------------------------------------------------- - - - - - _GENESIS AND GEOLOGY._ - - -------------- - - THE CHEMICAL HISTORY - - OF - - The Six Days of Creation. - - BY JOHN PHIN, C. E., - - EDITOR OF “THE AMERICAN JOURNAL OF MICROSCOPY.” - - _1 Vol., 12mo._ _Cloth._ _75 cents._ - - -------------- - - The following are a few of the Opinions of the Press: - -This is a small book, but full of matter. * * * We think this book is -full of interest and value; and as the discussions concerning the -harmony of science and faith are rife at the present day, we commend the -reasonings of Mr. Phin to the great number of readers and students who -are investigating these subjects.—_The Presbyterian_ (Philadelphia). - -The author gives a new solution of this difficult question, and -certainly presents many very plausible arguments in support of his -theory.—_Sunday-School Workman._ - -A very candid and ingenious essay.—_Christian Union_ (H. W. Beecher’s -paper). - -No one can read this book without compensation, without becoming more -thoughtful concerning the phenomena of creation; and he need lose none -of his reverence for the supremacy of the Divine Law.—_Rural New -Yorker._ - -We could say much in commendation of Prof. Phin’s little book. An -intelligent reader can hardly fail to be interested in it, and many -might be benefited.—_Country Gentleman._ - -The book can not fail to interest even those who do not fully accept the -theory it advocates.—_Boston Journal of Chemistry._ - -It is a new scientific view of the matter.—_Phrenological Journal._ - -The book, although not large, will prove exceedingly interesting to all -who have ever directed attention to this matter, and contains more solid -and suggestive thought than many voluminous treatises on the -subject.—_Insurance Monitor._ - -The work is ingenious and original, and presents many striking -suggestions.—_American Baptist._ - -We believe Prof. Phin has started upon the correct basis, and his theory -is mainly tenable. His views are presented in a manner which, though -terse, is easily comprehended.—_Daily Guardian_ (Paterson, N. J.) - ------------------------------------------------------------------------- - - - - - THE YOUNG SCIENTIST, - - A Practical Journal for Amateurs. - - =ISSUED MONTHLY. Price 50 Cents per year.= - -It is characteristic of young Americans that they want to be DOING -something. They are not content with merely _knowing_ how things are -done, or even with _seeing_ them done; they want to do them themselves. -In other words, they want to experiment. Hence the wonderful demand that -has sprung up for small tool chests, turning lathes, scroll saws, wood -carving tools, telegraphs, model steam engines, microscopes and all -kinds of apparatus. In nine cases out of ten, however, the young workman -finds it difficult to learn how to use his tools or apparatus after he -has got them. It is true that we have a large number of very excellent -text-books, but these are not just the thing. What is wanted is a living -teacher. Where a living teacher cannot be found, the next best thing is -a live journal, and this we propose to furnish. And in attempting this, -it is not our intention to confine ourselves to mere practical -directions. In these days of knowledge and scientific culture, the “Why” -becomes as necessary as the “How.” The object of the YOUNG SCIENTIST is -to give clear and easily followed directions for performing chemical, -mechanical and other operations, as well as simple and accurate -explanations of the principles involved in the various mechanical and -chemical processes which we shall undertake to describe. - -The scope and character of the journal will be better understood from an -inspection of a few numbers, or from the list of contents found on a -subsequent page, than from any labored description. There are, however, -three features to which we would call special attention: - -CORRESPONDENCE.—In this department we intend to place our readers in -communication with each other, and in this way we hope to secure for -every one just such aid as may be required for any special work on hand. - -EXCHANGES.—An exchange column, like that which has been such a marked -success in the _Journal of Microscopy_, will be opened in the Young -Scientist. Yearly subscribers who may wish to _exchange_ tools, -apparatus, books, or the products of their skill, can state what they -have to offer and what they want, _without charge_. Buying and selling -must, of course, be carried on in the advertising columns. - -ILLUSTRATIONS.—The journal will make no claims to the character of a -“picture book,” but wherever engravings are needed to make the -descriptions clear they will be furnished. Some of the engravings which -have already appeared in our pages are as fine as anything to be found -in the most expensive journals. - - Special Notice. - -As our journal is too small and too low-priced to claim the attention of -news dealers, we are compelled to rely almost wholly upon subscriptions -sent directly to this office. As many persons would no doubt like to -examine a few numbers before becoming regular subscribers, we will send -four current numbers as a trial trip for - - FIFTEEN CENTS. - - -------------- - - CLUBS. - -Where three or more subscribe together for the journal, we offer the -following liberal terms: - - 3 copies for $1.25 - 5 〃 〃 2.00 - 7 〃 〃 2.75 - 10 〃 〃 3.50 - -Advertisements, 30 cents per line. - -As postal currency has nearly disappeared from circulation, we receive -postage stamps of the lower denominations (ones, twos and threes) at -their full value. Postal orders are, however, much safer and more -convenient. To avoid delay and mistakes address all communications to -“THE YOUNG SCIENTIST, Box 4875, New York,” and make all checks and -orders payable to John Phin. - ------------------------------------------------------------------------- - - - - - =WHAT PEOPLE SAY OF US.= - -In a letter to the Editor, Oliver Wendell Holmes, the genial “Autocrat -of the Breakfast Table,” says: “I am much pleased with the YOUNG -SCIENTIST. It makes me want to be a boy again.” - -“It is a little publication, calculated to call out and educate all the -latent ingenuity and thirst for knowledge which the youthful mind -possesses, and we hope it will win its way into every household in the -land.”—[Scientific Press. - -“We have never seen a periodical, designed for youth, which came nearer -to our ideal of what such a journal should be.”—[Canadian Pharmaceutical -Journal. - -“The YOUNG SCIENTIST is one of the choicest publications for juvenile -minds in this country. Every page treats on subjects of importance to -young and old, portrayed in a clearly comprehensive manner, which at -once interests the young idea in its careful perusal.”—[Lapeer Clarion. - -“It seems to fill the bill.”—[Newport Daily News. - -“It is pleasing to note that its youthful subscribers will not be misled -by clap-trap advertisements or advertisements of patent medicines, which -will not be received at any price. The YOUNG SCIENTIST is doing good -work in setting its face against this class of humbugs.”—[Manufacturing -and Trade Review. - -“The work is a copiously illustrated monthly, and is full of practical -hints that will instruct and amuse the young folks.”—[Industrial School -Advocate. - -“A small but elegant and very instructive monthly.”—[Pittsburg -Chronicle. - -“Contains the best possible reading for the young of both -sexes.”—[Ottawa Journal. - -“We can safely recommend this magazine as one of the very best -publications for the young folks.”—[The Independent, Fenton, Mich. - -“This journal occupies a new field, and is needed to put the minds of -our youth on the right track to secure a correct understanding of the -nature of things.”—[Wayland Press. - -“It is ably edited by John Phin, who will make a large place in the -heart of the rising generation, if he persists in his venture. We hope -his success in the field will be equal to the article furnished—first -best.”—[Sunset Chimes. - -“The articles are written in a popular, readable style, and profusely -illustrated.”—Akron City Times. - -“The YOUNG SCIENTIST is excellent in conception, and well designed to -amuse and instruct young people.”—[Chicago Evening Journal. - -“The YOUNG SCIENTIST is a handsome monthly magazine, each number -containing about 16 pages, handsomely illustrated. It will supply a -place which has been heretofore unoccupied. The copy before us comes -fully up to the promise of the prospectus.”—[The Times, Iroquois, Mich. - -“It is a journal which should be in the hands of both young and old, and -is a great benefit to the young scientist as well as the advanced -professor. It is a thousand times more valuable than the dime novel -series, so much read by boys. Parents would do well to have it in their -households.”—[The Iron Home. - -“This publication is a new launch, and it is very gratifying to witness -the ableness which pervades its pages.”—Amherst Free Press. - ------------------------------------------------------------------------- - - - - - THE AMERICAN - - JOURNAL OF MICROSCOPY, - - AND - - _POPULAR SCIENCE_. - - -------------- - - PROSPECTUS. - -The object of the JOURNAL OF MICROSCOPY is to diffuse a knowledge of the -best methods of using the Microscope; of all valuable improvements in -the instrument and its accessories; of all new methods of microscopical -investigation, and of the most recent results of microscopical research. -The JOURNAL does not address itself to those who have long pursued -certain special lines of research, and whose wants can be supplied only -by elaborate papers, which, from their thoroughness, are entitled to be -called monographs rather than mere articles. It is intended rather to -meet the wants of those who use the microscope for purposes of general -study, medical work, class instruction, and even amusement, and who -desire, in addition to the information afforded by text-books, such a -knowledge of what others are doing as can be derived only from a -periodical. With this object in view, therefore, the publishers propose -to make the JOURNAL so simple, practical and trustworthy, that it will -prove to the advantage of every one who uses the microscope at all to -take it. - -ILLUSTRATIONS.—The JOURNAL will be freely illustrated by engravings -representing either objects of natural history or apparatus connected -with the microscope. - -TRANSACTIONS OF SOCIETIES.—THE AMERICAN JOURNAL OF MICROSCOPY is not the -organ of any Society, but it gives the proceedings of all Societies -whose officers send us a report. As the JOURNAL is devoted _wholly_ to -Microscopy, and is in good form and size for binding, no better medium -can be had for preserving the scientific records of any society. Matters -of mere business routine we are frequently obliged to omit for want of -room. - -EXCHANGES.—An important feature of the JOURNAL is the exchange column, -by means of which workers in different parts of the country are enabled, -without expense, except for postage, to exchange slides and materials -with each other. - - =TERMS.= - -During the first two years of its existence, the subscription to the -AMERICAN JOURNAL OF MICROSCOPY was only fifty cents per year, but at the -request of more than two-thirds of the subscribers, the size of the -JOURNAL has been doubled, and the price raised to - - =ONE DOLLAR PER YEAR.= - -Four copies for three dollars. Those who wish to economize in the -direction of periodicals, would do well to examine our clubbing list. - -FOREIGN SUBSCRIBERS.—The JOURNAL will be sent, postage paid, to any -country in the Postal Union for $1.24, or 5 shillings sterling per year. -English postage stamps, American currency or American postage stamps -taken in payment. In return for a postal order or draft for £1 5s., five -copies of the JOURNAL will be furnished and mailed to different -addresses. Make all drafts and postal orders payable to John Phin. - -BACK VOLUMES.—We have on hand a few copies of Vols. I and II, bound in -handsome cloth cases, which we offer for $1 25 each. Vols. I and II, -bound, and the numbers of Vol. III, as issued, we offer for $2.50. We -can no longer supply complete sets of 1876-7 in sheets. To those who -wish to examine the journal, we will send ten odd numbers for 25 cents. - - =Advertisements.= - -The JOURNAL OF MICROSCOPY, from its very nature, is a visitor to the -very best families, and its value as an advertising medium has therefore -proved to be much above that of average periodicals. A few select -advertisements will be inserted at the rate of 30 cents per line, -nonpariel measure, of which twelve lines make an inch. Address - - AMERICAN JOURNAL OF MICROSCOPY, - P. O. Box 4875, New York. - - - - ------------------------------------------------------------------------- - - - - - ● Transcriber’s Notes: - ○ Missing or obscured punctuation was corrected. - ○ Typographical errors were silently corrected. - ○ Inconsistent spelling was made consistent when a predominant form - was found in this book; otherwise it was not changed. - ○ Forms of the name Schäfer were regularized to match the title page - of his “A Course of Practical Histology.” - ○ Text that was in italics is enclosed by underscores (_italics_); - text that was bold by “equal” signs (=bold=). - - - - - -End of the Project Gutenberg EBook of Section-Cutting: A Practical Guide, by -Sylvester Marsh - -*** END OF THIS PROJECT GUTENBERG EBOOK SECTION-CUTTING: A PRACTICAL GUIDE *** - -***** This file should be named 55930-0.txt or 55930-0.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/5/9/3/55930/ - -Produced by Chris Curnow, Barry Abrahamsen, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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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. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: Section-Cutting: A Practical Guide - To the preparation and mounting of sections for the microscope, etc. - -Author: Sylvester Marsh - -Release Date: November 10, 2017 [EBook #55930] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK SECTION-CUTTING: A PRACTICAL GUIDE *** - - - - -Produced by Chris Curnow, Barry Abrahamsen, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - - -</pre> - - -<div class='figcenter id001'> -<img src='images/cover.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p><span class='small'>The cover image was created by the transcriber and is placed in the public domain.</span></p> -</div> -</div> -<div class='pbb'> - <hr class='pb c000' /> -</div> -<div> - <h1 class='c001'><span class='xxlarge'>SECTION-CUTTING:</span></h1> -</div> - -<div class='nf-center-c1'> -<div class='nf-center c000'> - <div><span class='large'>A PRACTICAL GUIDE</span></div> - <div class='c000'><span class='small'>TO THE</span></div> - <div class='c000'><span class='large'>PREPARATION AND MOUNTING OF SECTIONS FOR</span></div> - <div><span class='large'>THE MICROSCOPE,</span></div> - <div class='c000'><span class='large'><i>SPECIAL PROMINENCE BEING GIVEN TO THE</i></span></div> - <div><span class='large'><i>SUBJECT OF ANIMAL SECTIONS.</i></span></div> - <div class='c002'><span class='small'>BY</span></div> - <div class='c003'><span class='large'><span class='sc'>Dr.</span> SYLVESTER MARSH.</span></div> - <div class='c003'><i>WITH ILLUSTRATIONS.</i></div> - <div class='c003'><span class='small'>REPRINTED FROM THE LONDON EDITION, WITH NOTES AND AN APPENDIX</span></div> - <div><span class='small'>ON THE SELECTION AND CARE OF SECTION KNIVES.</span></div> - <div class='c002'><span class='large'>NEW YORK:</span></div> - <div><span class='large'>INDUSTRIAL PUBLICATION COMPANY.</span></div> - <div><span class='large'>1879.</span></div> - </div> -</div> - -<div class='pbb'> - <hr class='pb c004' /> -</div> -<div class='chapter'> - <span class='pageno' id='Page_i'>i</span> - <h2 class='c005'>PREFACE.</h2> -</div> -<p class='c006'>If we glance at any of the numerous magazines -devoted either wholly or in part to the subject of -microscopy, we shall hardly fail to be struck with -the numerous queries relating to <span class='fss'>SECTION-CUTTING</span>, -which are to be found in its pages. A simple explanation -of this wide-spread want is afforded by the -fact that the use of the microscope has at the present -day extended to (and is still rapidly spreading -amongst) vast numbers of students, who, in many -instances, possess neither the leisure nor the means -to refer for information to large and expensive text-books. -Moreover, were they actually to consult -such works, they would practically fail to obtain the -information of which they are in need, for the -coveted instruction is to be found in those treatises -only in a scattered and fragmentary form—no work -with which we are acquainted treating of the subject -in anything like a detailed manner. To fill this -<span class='pageno' id='Page_ii'>ii</span><i>vacuum</i> in the literature of microscopy the present -manualette has been prepared. Little claim is made -to originality, yet the book is by no means a mere -compilation, but the outcome of long and extensive -personal experience in the cutting and mounting of -microscopical sections. Every process described has -been put to the test of actual trial, so that its worth -may confidently be depended upon. Many of the -little points insisted upon in the ensuing pages will -doubtless to the practised microscopist appear superfluous -or even puerile; but a vivid recollection of our -own early failures and disappointments assures us -that it is just these very <i>minutiæ</i> of detail which will -be found most serviceable in directing and sustaining -the faltering footsteps of the tyro.</p> - -<p class='c007'><span class='sc'>St. Helens</span>, <i>September, 1878</i>.</p> -<div class='pbb'> - <hr class='pb c004' /> -</div> -<div class='chapter'> - <span class='pageno' id='Page_1'>1</span> - <h2 class='c005'>PREFACE TO AMERICAN EDITION.</h2> -</div> -<hr class='c008' /> -<p class='c006'>Dr. Marsh’s book cannot fail to promote the -practical study of histology wherever the English -language is spoken, and under ordinary circumstances -the students of this country might have been left to -the use of the London edition. But a careful reading -showed that one or two points which are perfectly -clear to British readers might be a source of -doubt and difficulty to students on this side. At -the present day in this country histology is a favorite -study with very many private students who have no -access to teachers or large libraries, and for the purpose -of smoothing their path we have added such information -as was obviously desirable. In the hope -that these additions will prove of value, we submit -the book to American readers.</p> -<p class='c007'><span class='sc'>New York</span>, <i>January, 1879</i>.</p> -<div class='pbb'> - <hr class='pb c004' /> -</div> -<div class='chapter'> - <span class='pageno' id='Page_3'>3</span> - <h2 class='c005'>CONTENTS.</h2> -</div> -<hr class='c009' /> - -<div class='nf-center-c0'> -<div class='nf-center c003'> - <div>PART I.</div> - </div> -</div> - -<table class='table0' summary=''> -<colgroup> -<col width='89%' /> -<col width='10%' /> -</colgroup> - <tr> - <td class='c010'>Introduction</td> - <td class='c011'><a href='#p1-01'>11</a></td> - </tr> - <tr> - <td class='c010'>On Cutting Unprepared Vegetable Tissues</td> - <td class='c011'><a href='#p1-02'>12</a></td> - </tr> - <tr> - <td class='c010'>On Cutting Unprepared Animal Tissues</td> - <td class='c011'><a href='#p1-03'>13</a></td> - </tr> - <tr> - <td class='c010'>Preparation of Vegetable Tissues</td> - <td class='c011'><a href='#p1-04'>15</a></td> - </tr> - <tr> - <td class='c010'>Preparation of Animal Tissues</td> - <td class='c011'><a href='#p1-05'>16</a></td> - </tr> - <tr> - <td class='c010'>Special Methods of Hardening</td> - <td class='c011'><a href='#p1-06'>19</a></td> - </tr> - <tr> - <td class='c010'>Cutting Hardened Tissues by Hand</td> - <td class='c011'><a href='#p1-07'>19</a></td> - </tr> - <tr> - <td class='c010'>Microtome</td> - <td class='c011'><a href='#p1-08'>20</a></td> - </tr> - <tr> - <td class='c010'>Æther Microtome</td> - <td class='c011'><a href='#p1-09'>24</a></td> - </tr> - <tr> - <td class='c010'>Section-Knife</td> - <td class='c011'><a href='#p1-10'>24</a></td> - </tr> - <tr> - <td class='c010'>Imbedding in Paraffine for Microtome</td> - <td class='c011'><a href='#p1-11'>26</a></td> - </tr> - <tr> - <td class='c010'>Employment of Microtome</td> - <td class='c011'><a href='#p1-12'>29</a></td> - </tr> - <tr> - <td class='c010'>Staining Agents</td> - <td class='c011'><a href='#p1-13'>31</a></td> - </tr> - <tr> - <td class='c010'>Carmine Staining</td> - <td class='c011'><a href='#p1-14'>32</a></td> - </tr> - <tr> - <td class='c010'>Mounting Media</td> - <td class='c011'><a href='#p1-15'>36</a></td> - </tr> - <tr> - <td class='c010'>Mounting in Glycerine</td> - <td class='c011'><a href='#p1-16'>38</a></td> - </tr> - <tr> - <td class='c010'>Uses of Freezing Microtome</td> - <td class='c011'><a href='#p1-17'>42</a></td> - </tr> - <tr> - <td class='c010'>Employment of Freezing Microtome</td> - <td class='c011'><a href='#p1-18'>43</a></td> - </tr> - <tr> - <td class='c010'>Logwood Staining</td> - <td class='c011'><a href='#p1-19'>47</a></td> - </tr> - <tr> - <td class='c010'>Absolute Alcohol</td> - <td class='c011'><a href='#p1-20'>50</a></td> - </tr> - <tr> - <td class='c010'>Clove Oil</td> - <td class='c011'><a href='#p1-21'>51</a></td> - </tr> - <tr> - <td class='c010'>Canada Balsam</td> - <td class='c011'><a href='#p1-22'>51</a></td> - </tr> - <tr> - <td class='c010'>Mounting in Balsam</td> - <td class='c011'><a href='#p1-23'>53</a></td> - </tr> - <tr> - <td class='c010'>Finishing the Slide</td> - <td class='c011'><a href='#p1-24'>55</a></td> - </tr> -</table> - -<div class='nf-center-c0'> -<div class='nf-center c003'> - <div><span class='pageno' id='Page_4'>4</span>PART II.</div> - </div> -</div> - -<table class='table1' summary=''> -<colgroup> -<col width='89%' /> -<col width='10%' /> -</colgroup> - <tr> - <td class='c010'>Special Methods</td> - <td class='c011'><a href='#p2-25'>57</a></td> - </tr> - <tr> - <td class='c010'>Bone</td> - <td class='c011'><a href='#p2-26'>57</a></td> - </tr> - <tr> - <td class='c010'>Brain</td> - <td class='c011'><a href='#p2-27'>59</a></td> - </tr> - <tr> - <td class='c010'>Cartilage</td> - <td class='c011'><a href='#p2-28'>60</a></td> - </tr> - <tr> - <td class='c010'>Coffee Berry</td> - <td class='c011'><a href='#p2-29'>62</a></td> - </tr> - <tr> - <td class='c010'>Fat</td> - <td class='c011'><a href='#p2-30'>63</a></td> - </tr> - <tr> - <td class='c010'>Hair</td> - <td class='c011'><a href='#p2-31'>63</a></td> - </tr> - <tr> - <td class='c010'>Horn, etc.</td> - <td class='c011'><a href='#p2-32'>64</a></td> - </tr> - <tr> - <td class='c010'>Intestine</td> - <td class='c011'><a href='#p2-33'>64</a></td> - </tr> - <tr> - <td class='c010'>Liver</td> - <td class='c011'><a href='#p2-34'>65</a></td> - </tr> - <tr> - <td class='c010'>Lung</td> - <td class='c011'><a href='#p2-35'>65</a></td> - </tr> - <tr> - <td class='c010'>Muscle</td> - <td class='c011'><a href='#p2-36'>66</a></td> - </tr> - <tr> - <td class='c010'>Orange-peel</td> - <td class='c011'><a href='#p2-37'>67</a></td> - </tr> - <tr> - <td class='c010'>Ovary</td> - <td class='c011'><a href='#p2-38'>67</a></td> - </tr> - <tr> - <td class='c010'>Porcupine Quill</td> - <td class='c011'><a href='#p2-39'>67</a></td> - </tr> - <tr> - <td class='c010'>Potato</td> - <td class='c011'><a href='#p2-40'>67</a></td> - </tr> - <tr> - <td class='c010'>Rush</td> - <td class='c011'><a href='#p2-41'>68</a></td> - </tr> - <tr> - <td class='c010'>Skin</td> - <td class='c011'><a href='#p2-42'>68</a></td> - </tr> - <tr> - <td class='c010'>Spinal Cord</td> - <td class='c011'><a href='#p2-43'>69</a></td> - </tr> - <tr> - <td class='c010'>Sponge</td> - <td class='c011'><a href='#p2-44'>71</a></td> - </tr> - <tr> - <td class='c010'>Stomach</td> - <td class='c011'><a href='#p2-45'>71</a></td> - </tr> - <tr> - <td class='c010'>Tongue</td> - <td class='c011'><a href='#p2-46'>71</a></td> - </tr> - <tr> - <td class='c010'>Vegetable Ivory</td> - <td class='c011'><a href='#p2-47'>72</a></td> - </tr> - <tr> - <td class='c010'>Wood</td> - <td class='c011'><a href='#p2-48'>72</a></td> - </tr> - <tr> - <td class='c010'>Note A,</td> - <td class='c011'><a href='#N-a'>75</a></td> - </tr> - <tr> - <td class='c010'>Note B,</td> - <td class='c011'><a href='#N-b'>75</a></td> - </tr> - <tr> - <td class='c010'>Note C,</td> - <td class='c011'><a href='#N-c'>76</a></td> - </tr> - <tr> - <td class='c010'>Note D,</td> - <td class='c011'><a href='#N-d'>76</a></td> - </tr> - <tr> - <td class='c010'>Note E,</td> - <td class='c011'><a href='#N-e'>76</a></td> - </tr> - <tr> - <td class='c010'>Note F,</td> - <td class='c011'><a href='#N-f'>77</a></td> - </tr> - <tr> - <td class='c010'>Note G,</td> - <td class='c011'><a href='#N-g'>77</a></td> - </tr> - <tr> - <td class='c010'>Note H,</td> - <td class='c011'><a href='#N-h'>93</a></td> - </tr> - <tr> - <td class='c010'>Note I,</td> - <td class='c011'><a href='#N-i'>94</a></td> - </tr> - <tr> - <td class='c010'><a href='#index'>Index</a></td> - <td class='c011'> </td> - </tr> -</table> -<div class='pbb'> - <hr class='pb c004' /> -</div> -<div class='chapter'> - <span class='pageno' id='Page_11'>11</span> - <h2 class='c005'>SECTION-CUTTING.</h2> -</div> -<hr class='c008' /> -<div class='chapter'> - <h2 class='c005'>PART I.</h2> -</div> - -<p class='c006'><a id='p1-01'></a>1. <i>Introduction.</i>—Many of the most interesting objects -with which the microscopist has to deal, cannot be -made to reveal their beauty or minute structure until -they have been cut into slices or <i>sections</i>, of such a degree -of thinness as to render them transparent, and thus -permit of their examination by transmitted light, with -objectives of varying power. Unfortunately, however, -very few of the objects of this class are, in their natural -condition, in a suitable state to be submitted to this -method of procedure. Some are of such a soft and -yielding nature that any attempt to cut them is an -utter failure, for in place of a perfect section being obtained, -nothing remains upon the knife but a mass of -diffluent pulp; others, again, are of such density as to -resist the action of any cutting instrument.</p> - -<p class='c012'>It is evident, therefore, that nothing can be done -with such refractory materials until, by subjection to -appropriate methods of preparation, they shall have -been reduced to such a consistence as to render them -suitable for cutting. How this is to be accomplished -will depend entirely upon the physical and chemical -<span class='pageno' id='Page_12'>12</span>nature of the substance to be operated upon. As the -various objects differ so widely from each other in -these respects, so must the methods of preparation -suitable to each also vary. It is clear, therefore, that -no general directions for attaining this end can be -given which would be of any practical value. It is -possible, however, and very convenient, to arrange the -various objects into groups or classes, to the treatment -of each of which certain general rules are applicable; -but there will still remain a comparatively numerous -series of objects whose individual peculiarities of structure -will demand for them correspondingly special -methods of preparation. When such objects come to -be spoken of, the particular treatment most suitable to -each will also be noticed.</p> - -<p class='c012'><a id='p1-02'></a>2. <i>On Cutting unprepared Vegetable Tissues.</i>—There -are some few substances, however, which may -with more or less success be cut into sections whilst in -their natural condition. Such objects are to be found -in the vegetable world in certain kinds of leaves and -allied structures, whilst in the animal kingdom they are -principally represented by the various internal organs -of man and the lower animals. Special directions are -given in text-books for the preparation of sections of -leaves and similar substances. For instance, it is recommended -to lay the leaf, etc., on a piece of fine -cork, and with a sharp knife to shave off thin slices, -cutting down upon the cork. Another plan is to place -the leaf, etc., between two thin layers of cork, and cut -through the mass. No method, however, is at once so -simple and successful as the process of imbedding in -<span class='pageno' id='Page_13'>13</span>paraffine. To do this, it is necessary to make a paper -mould by twisting a strip of stout writing paper round -a ruler, and turning-in the paper over the end of the -ruler. This mould, the height of which may vary -from an inch to an inch and a half, should now be -about half filled with melted paraffine mixture (§ 11), -the leaf or other object plunged into it, and held in -position by small forceps till the paraffine has become -sufficiently solidified to yield it a support. More of -the paraffine mixture is now poured in until the specimen -is thoroughly imbedded; the whole is to be put -away in a cold place for an hour or so, when the mass -will be found sufficiently firm to be cut with ease. -Sections may be made with a razor kept constantly -wetted with water, or, if the preservation of colour be -no object, methylated spirit may be employed for the -purpose. As the subsequent treatment of such sections -in no wise differs from that required by those cut in the -microtome, we shall defer its consideration until that -method of section has been described (§ 12).</p> - -<p class='c012'><a id='p1-03'></a>3. <i>On Cutting unprepared Animal Tissues.</i>—For -the cutting of fresh <i>animal</i> tissues several plans may -be followed. Thus, if a section of only very limited -area be required, it may be obtained by snipping a -piece off the tissue with a pair of bent scissors, which, -for this purpose, are so made that the blades are <i>curved -on the flat</i> (Carpenter). If this be carefully performed -it will be found that a large portion of the section -(particularly at the circumference) so obtained will be -sufficiently thin for examination. If a larger section -be desired, an attempt may be made to cut it with a -<span class='pageno' id='Page_14'>14</span>very sharp scalpel or razor, the blade of which whilst -in use must be kept <i>flooded</i> with water, or spirit, the -latter of which is to be preferred. Recourse may also -be had to <i>Valentin’s</i> knife. This consists of two long, -narrow blades, running parallel to each other, the distance -at which the blades are held apart, and which, of -course, determines the thickness of the section, being -regulated by means of a fine screw passing through -both blades. A milled head attached to this screw -gives a ready means of opening or closing the blades, -so as to bring them to the desired degree of approximation. -The method of using the knife is very simple. -After having “set” the blades at the desired distance -apart by means of the milled head, the tissue to be cut -is held in the left hand immersed in a basin of water. -The knife is now steadily and with a rapid motion -<i>drawn</i> through the tissue, care being taken that the -cut is made in such a manner that the blades move -from heel to point. By slightly separating the blades -and gently shaking them in the water, the section at -once becomes disengaged. After use, the blades must -be thoroughly dried, when they may be smeared with -some oil which does not readily oxidize. For this purpose, -a very suitable oil is that known as “Rangoon.”<a id='r1' /><a href='#f1' class='c013'><sup>[1]</sup></a> -Though it has been deemed advisable briefly to describe -the preceding methods of cutting unhardened tissues, -it will be found that for the purposes of the ordinary -microscopical student sections so obtained are of very -little value. They are always of very limited dimensions, -seldom of uniform thickness, and often so extremely -<span class='pageno' id='Page_15'>15</span>friable as to render it very difficult and frequently impossible -to submit them with safety to such further -treatment as is necessary to fit them for being mounted -as permanent objects. This method of section-cutting, -however, is not without its uses, for by its means the -medical practitioner is provided with a simple and -ready method of roughly investigating the structure of -morbid tissues, whilst to the general student it furnishes -an easy means of making a cursory examination -of certain substances, in order that he may determine -whether it be worth his while to subject them to some -of those various processes of hardening hereafter to be -described.</p> -<div class='footnote c014' id='f1'> -<p class='c012'><a href='#r1'>1</a>. <span class='small'><a href='#N-a'>Note A.</a></span></p> -</div> - -<p class='c012'><a id='p1-04'></a>4. <i>Preparation of Vegetable Tissues.</i>—Let us now -pass to a brief consideration of the methods usually -adopted for preparing the various objects for easy section. -In the case of <i>vegetable</i> tissues, not only do we, -as a rule, find their texture of too great density to be -readily cut in their natural condition, but they also -contain much resinous and starchy matter, of which it -is highly desirable to get rid. In order to do this we -first cut the substance (say a stem or root) into small -pieces, which are to be placed in water for three or four -days, by which time all the soluble gummy matters -will have disappeared. The pieces are now transferred -to a wide-necked bottle, containing methylated spirit,<a id='r2' /><a href='#f2' class='c013'><sup>[2]</sup></a> -which, in the course of a few days, will dissolve out all -the resin, etc. Many kinds of woody tissue are by -these processes reduced to a fit condition for immediate -cutting; others, however, are so hard as to render it -<span class='pageno' id='Page_16'>16</span>necessary to give them another soaking for some hours -in water, to bring them to a sufficient degree of softness -to cut easily. If the wood (as in some few refractory -cases will happen) be still too hard for section, a -short immersion in warm, or if necessary, in boiling -water, will not fail effectually to soften it. The treatment -of such members of the vegetable division as require -peculiar methods, will be found described in -future pages.</p> -<div class='footnote c014' id='f2'> -<p class='c012'><a href='#r2'>2</a>. <span class='small'><a href='#N-b'>Note B.</a></span></p> -</div> - -<p class='c012'><a id='p1-05'></a>5. <i>Preparation of Animal Tissues.</i>—<i>Animal</i> tissues -differ from one another so greatly, both in consistence -and in chemical composition, as well as in their -degree of natural hardness, that no general rules can -be given which would be applicable to the preparation -of the whole class. Such as are of any considerable -degree of hardness, as horn and kindred structures, -must be treated much in the same manner as the denser -varieties of wood, viz., by more or less prolonged immersion -in water—cold, hot, or boiling. Those which -are of extreme hardness, as bones and teeth, can be cut -only by following certain special methods, full details -of which will be found in the Second Part of this -work (§ 26). Many, and indeed the vast majority of -animal tissues, offer a direct contrast in point of hardness -to those we have just been considering. All the -internal organs of the body are, when freshly removed, -of much too soft a nature to permit, when in their unprepared -condition, of easy or perfect cutting. It is -upon bringing them to that critical degree of hardness, -which is often so difficult to attain, that the chief -secret of successful section-cutting depends; for unless -<span class='pageno' id='Page_17'>17</span>the hardening process has been carried up to, but not -beyond, a given point, which varies with different -tissues, the operator, however dexterous, will fail to -obtain satisfactory sections. For, if the hardening has -fallen short of this critical point, he is, to some extent, -in the same position as if he were dealing with unhardened -tissues; whilst, if this point has been exceeded, -the tissue will have become so brittle as to crumble -before the knife. For the purpose of hardening animal -tissues, the student has at his command two principal -agents, namely, alcohol and chromic acid, each of -which possesses advantages of its own, but the use of -each of which is also attended by its own inconveniences. -Thus, by the use of alcohol, there is very -much less risk of overhardening the specimen than if -chromic acid had been employed. Alcohol, however, -though a capital indurating agent in some instances, -does not answer so well in many others. Chromic acid -is, therefore, to be preferred for general use. It is, -however, a very delicate agent to manage, for unless -the greatest care be taken it is exceedingly likely to -overharden tissues submitted to its action, and when -this happens the specimen becomes utterly useless for -cutting, as there is no known means of removing the -extreme brittleness which it has acquired. By taking -the precautions now to be given, this overhardening -may generally be avoided. Let us harden a portion of -some viscus, say the kidney, for instance. Suppose -we cut from the organ five or six small pieces (from half -to three-quarters of an inch square, <i>not larger</i>). These -must be placed in a mixture of equal parts of methylated -<span class='pageno' id='Page_18'>18</span>spirit and water for three days, at the end of -which period they may be transferred to a solution of -chromic acid, made by dissolving twenty grains of the -pure acid in sixteen ounces of distilled water. The -solution should be kept in a wide-necked bottle furnished -with a glass stopper. At the expiration of seven -days, pour off the solution and replace it by fresh. -At the end of another week, carefully examine the -immersed tissues, and by means of a sharp razor see if -they have acquired the necessary degree of hardness to -allow of a section of <i>moderate</i> thinness being made. If -so, remove the pieces and put them into a stoppered -bottle containing from six to eight ounces of methylated -spirit. If, however, the hardening be found not -to be sufficiently advanced, the chromic acid solution is -to be poured off and again replaced by fresh. It will -now be necessary to examine the tissues at intervals of -about two days, until they are found to be sufficiently -hard, when they must be transferred to the spirit. -Under no circumstances, however, should they be permitted -to remain in the chromic acid longer than the -end of the third week, and though they should at this -time appear not to have undergone sufficient induration, -yet it will be advisable to transfer them to the -methylated spirit, which in a short time will <i>safely</i> -complete the process of hardening, without any risk -being run of the tissue becoming ruinously brittle. It -will be noticed, that when the specimens have been -transferred to spirit, the latter will in a day or two -become of a deep yellow color, whilst a thick flocculent -deposit falls to the bottom of the bottle. The tissues -<span class='pageno' id='Page_19'>19</span>should then be removed, the bottle emptied and well -washed, and, being refilled with clean spirit, the preparations -are again to be replaced. This may occasionally -be repeated, until the spirit becomes and remains perfectly -bright and clear. The specimens are then ready -for section.</p> - -<p class='c012'><a id='p1-06'></a>6. <i>Special Methods of Hardening.</i>—The brain -(§ 27), spinal cord (§ 43), liver (§ 34), and several -other organs, etc., require special methods of hardening, -details of which will be found in the paragraph -devoted to each. In the case of <i>injected</i> preparations, -the best plan is to harden them in alcohol from the -outset, beginning with weak spirit, and gradually increasing -the strength as the hardening proceeds. -When the object has been injected with Prussian blue, -a few drops of hydrochloric acid should be added to -the alcohol to fix the color.</p> - -<p class='c012'>It may here be observed, that specimens of <i>morbid -tissues</i> require, as a general rule, a shorter immersion -in chromic acid solution than healthy tissues do. A -very small degree of overhardening speedily renders -them brittle and useless. They should, therefore, be -removed from the acid medium at the end of ten days -or a fortnight, and their further hardening carried on -by means of alcohol.</p> - -<p class='c012'><a id='p1-07'></a>7. <i>Cutting Hardened Tissues by Hand.</i>—Our material -being now reduced to a fit condition for cutting, -let us proceed to consider the several methods by which -this may be effected. The readiest and most simple -plan, if the piece be large enough, is to hold it in the -left hand, and, having brought the surface to a perfect -<span class='pageno' id='Page_20'>20</span>level by cutting off several rather thick slices, endeavor -to cut a thin section by the aid of a very sharp razor, -the blade of which must be kept well <i>flooded</i> with -spirit. As in the use of <i>Valentin’s</i> knife, so here, -great care must be taken steadily to <i>draw</i> the blade -across the tissue, every effort being made to avoid -<i>pushing</i> the knife, else the section will be <i>torn off</i>, instead -of being <i>cut</i>. Though this method<a id='r3' /><a href='#f3' class='c013'><sup>[3]</sup></a> is of very -great importance for many purposes, yet a considerable -degree of manipulative skill is required to enable -the operator to obtain anything like perfect sections by -its means, and, unfortunately, this skill is acquired by -very few persons indeed, even after much practice. -If the piece which it is desired to cut be too small to -be conveniently held in the hand, it may be imbedded -in paraffine in the manner already described (§ 3). A -very simple imbedding agent, and one of the greatest -practical value, is a strong solution of gum arabic, -which, upon being dehydrated either by ordinary drying -or the action of alcohol, soon acquires such a degree -of hardness as to permit it (with the imbedded tissue) -to be cut with ease. As this method of imbedding, -however, is most frequently resorted to where, by its -means, special difficulties have to be overcome, a full -description of the process (§ 35) will be deferred until -such special cases come to be spoken of.</p> -<div class='footnote c014' id='f3'> -<p class='c012'><a href='#r3'>3</a>. <span class='small'><a href='#N-c'>Note C.</a></span></p> -</div> -<p class='c012'><a id='p1-08'></a>8. <i>Microtome.</i>—Although the preceding plans may -be sufficient to answer all his requirements, if the student -wishes to obtain only one or two sections of small -dimensions, of a given object, if he requires a number -<span class='pageno' id='Page_21'>21</span>of such sections he will find these methods fail him, for -even though by practice he may have attained to considerable -aptitude in the use of the knife, it will still unquestionably -happen that the vast majority of his sections -will be more or less imperfect. If, therefore, it -be desired to procure a number of perfect sections, of -equable thickness and large area, it is absolutely necessary -to resort to the use of some form or other of microtome, -or section-cutter. This instrument, in its simplest -form, merely consists of a stout brass tube closed -at one end, and being by the other fixed at right angles -into a smooth plate of metal. A plug or disk of brass, -accurately fitting the interior of the tube, is acted upon -by a fine threaded screw piercing the base of the tube, -and by means of which the plug, and any object it may -support, can be elevated at pleasure. The object by -this means being made gradually to rise out of the tube, -sections are cut from it by simply gliding a sharp knife -along the smooth cutting-plate, and hence across the -specimen. Any intelligent worker in brass would make -an instrument of this kind at a very small cost, and -although perhaps it might lack the finish of an instrument -bought at the optician’s, it would, if accurately -made, do its work as well as the most complicated and -expensive. If, however, the student resolves to purchase -a microtome, there are a variety of forms in the -market from which he may choose. A few hints may -perhaps be of service in enabling him to make a judicious -selection. At the outset we may say that unless -the student intends to devote himself solely to the production -of sections of wood, etc., he ought not to procure -<span class='pageno' id='Page_22'>22</span>one of those forms of microtome known as wood -section-cutters, in which the object to be cut is held in -position in the tube by means of a binding screw which -pierces its side.<a id='r4' /><a href='#f4' class='c013'><sup>[4]</sup></a> Although these machines are all that -can be desired for cutting hard bodies, they are not so -suitable for soft ones. The chief points to be attended -to in selecting a microtome are, (1) that the cutting-plate -of the instrument be made of glass, or in default -of this, of very hard metal of the most perfect smoothness;<a id='r5' /><a href='#f5' class='c013'><sup>[5]</sup></a> -(2) that the diameter of the tube be neither too -large nor too small—it ought not to be less than 5/8-in., -or greater than 1 inch;<a id='r6' /><a href='#f6' class='c013'><sup>[6]</sup></a> (3) that the screw, which should -be <i>fine</i> and well cut, be provided with a graduated -head; (4) that there be some kind of index by which -fractional portions of a revolution of the screw may be -measured; and (5) that the plug fit the tube of the -microtome so accurately that when melted paraffine, -gum, or other imbedding agent be poured into it, it -may not find its way between the plug and side of the -tube (§ 18). It often happens in cutting tissues imbedded -in paraffine, that the pressure of the knife -causes the cylinder of the imbedding agent to twist -round in the tube of the machine, and so cause considerable -difficulty and annoyance. This evil is usually -met by running a deep groove across the upper surface -of the plug, and into this the paraffine sinks, and so is -prevented from rotating. It will be found, moreover, -that another difficulty of a kindred, though much more -serious character, will frequently be encountered. During -section the paraffine has a tendency not only to -<span class='pageno' id='Page_23'>23</span>rotate, but also to become loosened from the subjacent -plug, and to <i>rise</i> in the tube of the microtome. When -this happens the power to cut sections of uniform -thickness has completely gone, for some will now be -found to be many times thicker than others; in fact, -the irregularity in this respect soon becomes so monstrous -as to render it useless to prolong the sitting. In -the ordinary run of microtomes no provision seems to -have been made to meet this difficulty, and for this -reason many instruments, of otherwise great merit, -have their efficiency seriously impaired. Fortunately, -this imperfection is easily remedied, all that is required -being that the upper surface of the plug should be furnished -with some kind of projection, having at its summit -a table-like expansion, as shown at A in the figure. -The imbedding paraffine, by penetrating beneath and -around this, becomes firmly attached to the plug, and -thus all risk of its rising is effectually avoided. If the -student wishes to secure a really first-class instrument, -<span class='pageno' id='Page_24'>24</span>none can be so confidently recommended as the freezing -microtome of Professor Rutherford. In addition -to its being the best instrument for carrying out the -freezing method (§ 18), this machine is equally effective -for cutting tissues imbedded in paraffine, or any of the -other agents used for that purpose; indeed, whatever -work a microtome <i>can</i> do, <i>this one</i> will perform.</p> -<div class='footnote c014' id='f4'> -<p class='c012'><a href='#r4'>4</a>. <span class='small'><a href='#N-d'>Note D.</a></span></p> -</div> - -<div class='footnote c014' id='f5'> -<p class='c012'><a href='#r5'>5</a>. <span class='small'><a href='#N-e'>Note E.</a></span></p> -</div> - -<div class='footnote c014' id='f6'> -<p class='c012'><a href='#r6'>6</a>. <span class='small'><a href='#N-f'>Note F.</a></span></p> -</div> - -<div class='figcenter id002'> -<img src='images/i_023.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>SECTION OF MICROTOME-TUBE SHOWING ARRANGEMENT (A) TO PREVENT “RISE” OF PARAFFINE.</p> -</div> -</div> - -<p class='c012'><a id='p1-09'></a>9. <i>Æther Microtome.</i>—A word here as to freezing -microtomes, where the agent used is æther. Such as -have fallen under our notice have not answered the -expectations we were justly entitled to form of them. -That it is possible to freeze a piece of tissue by their -use is undeniable, but it is, as a rule, at an expenditure -of such a quantity of æther (only the very best of which -must be used) as to constitute it a very expensive proceeding. -Another serious disadvantage they possess is, -that if the supply of æther be intermitted for only a -very short time, the already frozen tissue thaws with -great and most inconvenient rapidity.</p> - -<p class='c012'><a id='p1-10'></a>10. <i>Section-Knife.</i>—Of not less importance than -the microtome is the section-knife, to be used in conjunction -with it. How perfect soever the former, and -whatever the dexterity of the operator, unless he be -provided with a suitable and well-made knife, he will -never succeed in obtaining satisfactory results. As to -the most desirable <i>size</i> of the knife, much difference -of opinion seems to exist, section knives varying in this -respect from a blade of extreme shortness to one which -fell under our observation, in which the portentous -length of <i>thirteen</i> inches was attained. What advantages -were to be expected by prolonging the blade to -<span class='pageno' id='Page_25'>25</span>this extravagant length, must remain an inscrutable -mystery to all save its designer. Concerning the <i>shape</i> -of the knife, it is frequently advised that the surface -which has to glide along the cutting-plate of the microtome -should be ground <i>flat</i>. A most unsuitable -arrangement, as a very little actual experience of -section-cutting will speedily demonstrate. After many -unsuccessful attempts to obtain a really good and reliable -section-knife, we determined to have one specially -made, which, as it has proved everything that could be -desired, merits a brief description. It is of the utmost -importance that the blade be made of good and well-tempered -steel, not only that it may be capable of receiving -an edge of the most exquisite keenness, but -also that it may <i>retain it</i>. The knife of which we -speak (and which was made by Mr. Gardner, of South -Bridge, Edinburgh) is furnished with a blade <i>four -inches</i> long, and 7/8-inch broad, set into a square handle -of boxwood, also four inches in length. The thickness -of the blade at the back is not quite 1/4-inch, while <i>both</i> -of its surfaces are slightly hollow ground. It is essentially -necessary that the back and edge of the blade be -strictly parallel to each other, otherwise the knife, when -in use, will have such a tendency to tilt over as to -render its management extremely difficult. It is very -easy to discover if this condition be fulfilled, for if on -carefully laying the flat of the blade upon a piece of -level glass, every portion of both back and edge are -found to be in close contact with it, the knife may in -this respect be considered perfect. Every student who -aspires to be a successful section-cutter should provide -<span class='pageno' id='Page_26'>26</span>himself with a good Turkey oilstone, <i>and learn to use it</i>. -He should also possess a razor strop, as it will be in -constant requisition.<a id='r7' /><a href='#f7' class='c013'><sup>[7]</sup></a> It may here be remarked that -though <i>razors</i>, as a rule, are unsuitable for use with -the microtome from want of uniformity in the thickness -of their blades, yet, if only a small object is to be -cut—for instance, a thin root or stem—very good results -may be obtained from their use, especially if one -of the old-fashioned make, having a thick back and -slightly <i>concave</i> surfaces, be employed.</p> - -<p class='c012'><a id='p1-11'></a>11. <i>Imbedding in Paraffine for Microtome.</i>—Having -described at some length the various instruments -necessary for section-cutting, we will now consider how -they are to be used. Let us endeavor to cut some -sections—say of a piece of kidney—and in so doing we -will adopt the “paraffine” method of imbedding. -Ordinary paraffine, however, when used alone, is -rather too hard for our purpose. In order, therefore, -to bring it to a suitable consistence, it must be mixed -with one-fifth its weight of common unsalted lard, a -gentle heat applied, and the two thoroughly stirred -together. A quantity of this should be prepared, so -that it may always be ready when wanted—it is very -conveniently kept in an ointment pot or preserve jar, -the top of the latter being well covered, to keep out -the dust. When it is intended to use this mixture for -the purpose of imbedding, only just about the quantity -required should be melted; for in doing this it is advisable -to use as low a degree of heat as possible, not -only to prevent injury to the tissue to be imbedded, -<span class='pageno' id='Page_27'>27</span>but also that the paraffine when cooling may not undergo -such an amount of contraction as to cause it to -shrink from the sides of the microtome-tube. It is -therefore a good plan to effect the melting in a water-bath, -a simple kind of which, something after the -fashion of a glue-pot, would be made for a few pence -by any tinman.</p> -<div class='footnote c014' id='f7'> -<p class='c012'><a href='#r7'>7</a>. <span class='small'>See <a href='#N-g'>Note G.</a></span></p> -</div> - -<p class='c012'>The kidney which we are about to cut has, of -course, gone through the process of hardening already -described (§ 5), and is now preserved in spirit. A small -piece, say half an inch square, is selected, removed -with forceps, and placed on a bit of blotting paper, -when the surface of the tissue will rapidly become dry -(<i>only the surface</i> must be allowed to dry). It is the -usual plan now to proceed at once to imbed it in the -melted paraffine. This is a most undesirable step, and -gives rise at a later stage of our proceedings to a great -amount of trouble and annoyance, for after sections -have been cut from a tissue so imbedded it will be -found that portions of paraffine adhere to their edges -with such tenacity that in the case of many of them -there is no effectual method of removing the paraffine, -short of soaking the sections in warm æther; a very -objectionable proceeding, for though the æther will -undoubtedly remove the paraffine, it will also dissolve -out any fatty matters which the section itself may naturally -contain. All this annoyance may be prevented -by subjecting the tissue to a simple preparatory treatment -before it is imbedded in the paraffine. For this -purpose prepare a very <i>weak</i> solution of gum arabic in -water—twenty grains to the ounce. Into this, by -<span class='pageno' id='Page_28'>28</span>means of the forceps, dip for a few moments the already -<i>surface-dried</i> tissue, taking special care not to squeeze -it, or the pressure will cause the spirit from its interior -to remoisten the surface, which would prevent the -gum from adhering. We shall see the value of this a -little later on. Remove the tissue from the solution -on to blotting paper, when the superfluous gum will -speedily drain off, and in two or three minutes the -<i>surface</i> will have become quite glazy and dry. Having -melted some paraffine mixture in the water-bath, the -tissue held in the forceps must be plunged for an instant -into the heated liquid and immediately withdrawn, -when the crust of paraffine with which it is -enveloped will promptly harden. Whilst this is taking -place we may make ready the microtome. Having by -means of the milled head or handle depressed the plug -in the tube so as to leave a free opening about an inch -deep at its upper end, we must pour in the melted -paraffine, which by this time will have become a little -cooler, until the cavity be about half filled. The prepared -tissue must now be introduced, care being taken -to place it in such a position that the sections may be -cut in the desired direction. The tissue must, if necessary, -be held in position with forceps or a needle -point, till the imbedding material becomes hard enough -to give it due support. It is here to be remembered -that it will not be advisable to place the tissue in the -centre of the tube—it will be much more easily cut if -placed rather nearer to that edge of the tube which is -situated next the operator in the act of cutting. More -paraffine is to be slowly added, until the tissue is completely -<span class='pageno' id='Page_29'>29</span>covered; even after this still more should be -added, for it will be found that in cooling the paraffine -shrinks so as to leave a cup-shaped depression in its -centre, whereby portions of the tissue which were previously -covered are again laid bare. The best method -of preventing this is to use the paraffine at as low a -temperature as possible, and to use plenty of it. The -microtome, with its contents, must now be removed to -a cool place, when the paraffine will soon become solidified. -Whilst this is being accomplished we may -make our further preparations. The first thing we require -will be a large basin, full of freshly-filtered water, -and provided with a cover. A small beaker of methylated -spirit, with a dipping rod or pipette, will also be -necessary. We must now see that the section-knife is -in thorough order, to ensure which it will be advisable -to give it a few turns on the strop. An ordinary razor -will also be of service.</p> - -<p class='c012'><a id='p1-12'></a>12. <i>Employment of Microtome.</i>—The paraffine being -sufficiently hard, we will clamp the microtome on to -the table, and seat ourselves on a chair of convenient -height before it. To our right stand the basin of -water, razor, and section-knife; the beaker of spirit to -the left, and a cloth on our knee. A few turns of the -microtome screw having brought the paraffine to the -surface, a thick slice is to be cut off, and this repeated -until the imbedded tissue comes into view. This -preliminary work had best be done with the razor, as -it is needless to subject our section-knife to unnecessary -wear and tear. By a fractional revolution of the screw -the tissue is now slightly elevated, and with the pipette -<span class='pageno' id='Page_30'>30</span>held in the left hand, a large drop of spirit is to be let -fall upon its surface. The section-knife, grasped firmly -but lightly in the right hand, is to be laid flat upon the -cutting-plate of the machine, so as to occupy the -diagonal position shown in the figure. Two fingers of -the left hand are now laid gently upon the back of the -blade, so as to give it an equable support, whilst the -knife with a rapid motion is pushed in the combined -direction of <i>forwards</i> and to the <i>left</i>, so that the blade -in cutting the tissue will pass through it from point to -heel. Thus it will be observed that the stroke of the -knife is <i>from</i> the operator—a far easier and more effective -mode of cutting than the reverse plan. The -blade of the knife, having the section just cut, either -floating in a small pool of spirit on its surface or adhering -thereto, must now be immersed in the basin of -water, when by a little very gentle agitation of the -<span class='pageno' id='Page_31'>31</span>knife the section will be floated off. And now we -shall find the great practical value of immersing the -tissue in gum before imbedding, for no sooner is the -section disengaged from the knife than the thin film -of gum which separates the paraffine from it becomes -dissolved, and the section will be observed gradually to -subside to the bottom, leaving the paraffine floating -upon the surface. After carefully wiping the knife -from all shreds of paraffine, the microtome screw must -again be partially revolved, more spirit applied to the -tissue, and another section being cut, it must be transferred -to the water as before, and so on, until a sufficient -number of sections have been obtained. As to -how thin the sections should be cut, no general directions -can be given; each case must be regulated by its -own conditions. The denser the tissue, the thinner -should the section be; whilst certain substances of loose -and spongy texture do not require the sections to be -particularly thin—it may be said, however, in a general -way that sections, and especially animal ones, <i>cannot -be cut too thin</i> so long as they remain perfect and entire. -If Professor Rutherford’s microtome (as made by Gardner) -be employed, the head of the screw will be found -to be graduated into divisions of slightly unequal -value; the sections will therefore be marked by corresponding -variations of thickness, so that amongst a -number cut, there must be many of the exact thickness -to meet the requirements of any individual case.</p> - -<div class='figcenter id001'> -<img src='images/i_030.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>DIAGRAM SHOWING DIAGONAL POSITION OF KNIFE IN COMMENCING TO MAKE A SECTION.</p> -</div> -</div> - -<p class='c012'><a id='p1-13'></a>13. <i>Staining Agents.</i>—Before proceeding to mount -the sections which have just been cut, it will be very -advisable that they should be submitted to the action -<span class='pageno' id='Page_32'>32</span>of some staining fluid, in order to render more clear -and distinct their minute structure. Organic substances -possess the property of being able to absorb -various colouring matters from their solution, and to -incorporate such colour into their own texture. This -power of attraction is not, however, possessed by all -substances indiscriminately, or to an equal extent. -Some possess it in a high degree, while others appear -to be nearly, if not entirely, devoid of such power. -Hence it follows, that if we immerse an organic tissue -(one of our sections, for instance) of complex structure, -in a suitable staining fluid, the tissue will not become -stained in an even and uniform manner throughout, -but the several portions of it will receive varying depths -of colour in accordance with the varying attractive -power of its several constituents. By this means we -are enabled in stained sections to discriminate by their -difference of shade, minute and delicate structures, -which in the unstained condition it would be difficult -and often impossible to differentiate. For the purpose -of section-staining there are many agents in use, the -most generally suitable being carmine, logwood (§ 19), -and aniline blue (§ 27); whilst for special purposes -chloride of gold (§ 28), pyrogallate of iron (§ 28), and -several others are all of much value.</p> - -<p class='c012'><a id='p1-14'></a>14. <i>Carmine Staining.</i>—In the case of animal sections, -carmine is, as a rule, to be selected, giving as it -does most satisfactory and beautiful results. Tissues -may be stained with carmine by two different plans: in -the first, a strong solution is used, and the tissue subjected -to its action for a very short period only, whilst -<span class='pageno' id='Page_33'>33</span>in the latter only very weak solutions are employed, the -time of immersion being considerably prolonged. The -rapid method, however, is not to be recommended, for -the strong carmine acts so powerfully upon the tissue -as to give the various elements comprising it no time, -as it were, to exercise their power of quantitive selection, -but involves the whole in one uniform degree of -shadeless colour. By adopting the gradual method -much better results are obtained, each portion of the -tissue being now at liberty to acquire its own particular -shade. Amongst the various formulæ for the preparation -of carmine fluid, none can be so safely followed -as that devised by Dr. Lionel Beale. It runs thus:—Place -ten grains of the finest carmine in a test tube, -add thirty minims of strong liquor ammonia, boil, add -two ounces of distilled water, and filter; then add two -ounces of glycerine, and half an ounce of rectified -spirit—this solution ought to be kept in a well stoppered -bottle. The best vessels in which to stain sections -are small jars of white porcelain, capable of holding -about two fluid ounces, and furnished with lids—they -are much preferable to beakers or watch glasses, -for owing to the white background which they afford -it is very easy to watch how the staining is proceeding. -The carmine solution which we have just described is -both too strong and of too great density to be used in its -pure state. It will, therefore, require to be diluted -with distilled water before use—the most useful degree -of dilution being attained by adding one part of stain -to seven of water. Sections may be placed in this solution -for twenty-four hours, in which time they will -<span class='pageno' id='Page_34'>34</span>usually be found to have acquired a sufficient depth of -colour. If, however, the tissue be unusually difficult -to stain, the time of immersion may be doubled, or still -further prolonged, without detriment to the section.</p> - -<div class='figcenter id001'> -<img src='images/i_034.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>SECTION SPOON.</p> -</div> -</div> - -<p class='c012'>Having prepared and filtered some of this dilute -solution, say an ounce, let us proceed to stain with it -those sections which we left in the basin of water (§ 12). -Here we are at once met by a practical difficulty. How -are the sections to be transferred from one vessel to the -other? This is ordinarily effected by means of a soft -camel’s-hair pencil. It is a method, however, open to -grave objections, for the sections so curl around the -brush, and get entangled amidst its hairs, that, notwithstanding -every care, valuable sections not unfrequently -become torn during transit. Every difficulty -at once vanishes if we substitute for the brush a small -implement, which any one can readily make for himself. -All that is necessary is to take a strip of German-silver, -or copper, of the thickness of stout cardboard, -and about seven inches in length by five-eighths of an -<span class='pageno' id='Page_35'>35</span>inch in breadth. The sharp angles are to be filed off -and the edges carefully smoothed, whilst at a distance of -five-eighths of an inch from each extremity the end must -be turned up so as to form an angle of about 35°. One -end must be left plain, whilst the other, with the aid -of a punch or drill, is to be pierced with five holes -about the thickness of a stocking needle<a id='r8' /><a href='#f8' class='c013'><sup>[8]</sup></a> (see Figure). -If we now dip the perforated end of this spoon into the -water containing the sections, and gently agitate it, -the sections will rise from the bottom and float about. -The spoon is now brought under one of them, and -being steadily lifted up the water flows downwards -through its apertures, and the section smoothly spreading -itself out upon the spoon, may be gently lifted out -of the water, and on the spoon being dipped into the -staining fluid the section at once floats off. By this -simple means sections, however large, thin or delicate, -may with ease be conveyed from one fluid to another, -with the utmost certainty of their not being injured -during the process. The sections having been in the -carmine fluid for about twenty-four hours, as much of -the liquor as is possible must be gently poured off, and -its place supplied by a freshly-filtered mixture of five -<span class='pageno' id='Page_36'>36</span>drops of glacial-acetic acid to one ounce of water, when -in a few moments the carmine will become permanently -<i>fixed</i> in the tissue, and the process of staining be complete.</p> -<div class='footnote c014' id='f8'> -<p class='c012'><a href='#r8'>8</a>. <span class='small'>Dr. Klein describes a kind of “lifter,” made by bending -some German-silver wire, but as no drawing accompanies his -description, it is not easy to form a clear idea as to the form of -this instrument. In the recent and philosophical work of Schäfer, -a lifter is figured, which consists of a wire stem, having attached -to its end a spade-like blade. It will be observed that the spoon -described in the text differs from this lifter in having one end -perforated, and in this consists the real value of the implement.</span></p> -</div> - -<p class='c012'><a id='p1-15'></a>15. <i>Mounting Media.</i>—The further treatment of -the stained sections will entirely depend upon the -nature of the medium in which it is intended to mount -them. There are a variety of fluids in use for this -purpose, the principal being dilute alcohol (§ 26), -dammar, or Canada balsam (§ 22-23), and glycerine. -These, however, cannot be used indiscriminately, each -possessing certain special properties which render it -suitable for use with particular classes of objects only. -Thus, weak spirit, having no tendency to increase the -transparency of objects, can advantageously be used -with such only as are already perfectly transparent. -It is also more suitable for the preservation of vegetable -tissues (when the retention of colour is no object) -than animal, since with the latter it has a tendency -after a while to cause a kind of granular disintegration, -which ultimately destroys much of the usefulness of -the preparation. Dammar and Canada balsam, on the -other hand, possess very great refractive power, so that -they are of great service in mounting objects which -require their transparency to be much increased. For -this reason they are not well adapted to the preservation -of very delicate or transparent tissues (unless previously -stained), the minute details of which become -almost entirely obliterated when mounted in them. -The chief advantage possessed by these resinous media -is, that tissues mounted in them undergo no alteration, -<span class='pageno' id='Page_37'>37</span>even after the lapse of many years. Glycerine, in respect -of its clarifying powers, occupies an intermediate -position between spirit and balsam, being much more -refractive than the former, infinitely less so than the -latter. It is, therefore, of very great value for the -preservation of such tissues as possess a medium degree -of transparency, and which would become obscured if -mounted in spirit, or have their outlines rendered indistinct -if preserved in balsam. It is of the utmost -value for mounting unstained anatomical sections -which, when put up in this medium, reveal such -minute details of structure as would readily have escaped -observation had any other agent been employed. -It may also be used with stained sections, but in this -case the sections should be of extreme thinness, otherwise -the refractive power of the glycerine will be insufficient -to render them thoroughly transparent. The -great drawback to the use of glycerine is the extreme -difficulty experienced in preventing its escape from -beneath the covering glass, for it unfortunately possesses -such great penetrating power that no cement -hitherto devised can be thoroughly depended upon for -withstanding its solvent action for any considerable -length of time.<a id='r9' /><a href='#f9' class='c013'><sup>[9]</sup></a> Attention to the instructions presently -to be given (§ 16) will, however, reduce this risk -of leakage to a minimum. In the use of glycerine Dr. -Carpenter’s caution must ever be borne in mind, viz., -that, as carbonate of lime is in time dissolved by -glycerine, this agent ought never to be employed for -the preservation of objects containing such salt.</p> -<div class='footnote c014' id='f9'> -<p class='c012'><a href='#r9'>9</a>. <span class='small'><a href='#N-h'>Note H.</a></span></p> -</div> - -<p class='c012'><span class='pageno' id='Page_38'>38</span><a id='p1-16'></a>16. <i>Mounting in Glycerine.</i>—To illustrate the -method of using this medium we will mount our present -sections in glycerine. In the first place we shall -require a deep watch-glass, which is to be half filled -with glycerine diluted with an equal amount of distilled -water. By means of the spoon, one or more sections -may be transferred into this, either directly from the -acetic acid solution (§ 14), or if, since cutting, they -have been preserved in spirit, they should first undergo -a short immersion in a large vessel full of water. The -watch-glass should now be covered with an inverted -wine-glass, and put away for some hours, in order that -the sections may become thoroughly saturated with the -dilute glycerine. When this has been accomplished, a -slide must be cleaned, and one of the sections, with -the aid of the <i>unpierced</i> end of the spoon, be transferred -to its centre.<a id='r10' /><a href='#f10' class='c013'><sup>[10]</sup></a> As the kind of section with -which we are now dealing is, or ought to be, of extreme -<span class='pageno' id='Page_39'>39</span>thinness, no cell (§ 26) is necessary. After tilting -up one end of the slide, so as to drain off as much -of the weak glycerine as possible, a drop of Price’s best -glycerine must, with a glass rod or pipette, be allowed -to fall gently upon the section, so as to avoid the formation -of air-bubbles. If any of these, however, -should be produced, they must be removed with the -point of a needle set in a wooden handle,<a id='r11' /><a href='#f11' class='c013'><sup>[11]</sup></a> and the -slide then covered with a small bell-glass (or wine-glass). -A circular cover is now to be cleaned with a -soft handkerchief, and after gently blowing from it -any adhering fibres of lint, etc., it will be advisable to -hold the side of the glass which is to come into contact -with the preparation close to the mouth, and breathe -upon it, so as to cover it with moisture. The cover -held between the thumb and forefinger of the left hand -must now be applied by its edge near to the margin of -the preparation, and the surface of the cover directed -in an inclined manner over it. Beneath the overhanging -edge of the cover the point of the needle, held in -the right hand, is now to be inserted (see Figure). By -gently lowering the needle, the cover will come into -gradual contact with the slide, driving before it a -<span class='pageno' id='Page_40'>40</span>minute wave of glycerine, in which any air-bubbles -that may have become developed are usually carried off. -A very considerable degree of tact, however, is required -to perform this little operation, simple as it may appear, -for the retreating wave of glycerine not unfrequently -floats out the section, either wholly or partially, -from beneath the cover. Air-bubbles, also (the <i>bêtes -noires</i> of this process), are exceedingly likely to arise. -When this happens the best plan to adopt is, by means of -the needle point, gently to raise and remove the cover, -apply another drop of glycerine to the section, and -cover <i>with a fresh piece of thin glass</i>. It will now be -necessary to remove any superfluous glycerine which -may have collected around and near the cover. The -great bulk must be wiped away by means of a camel’s-hair -pencil, slightly wetted between the lips, any remaining -stickiness being removed with a bit of blotting -paper which has been slightly damped. With a very -small camel’s-hair pencil, charged with solution of -<span class='pageno' id='Page_41'>41</span>gelatine, a ring must be made round the margin of the -cover, of sufficient breadth to take in a small tract of -both cover and slide. As this cement is perfectly miscible -with glycerine, it readily unites with any of that -fluid which may ooze from beneath the cover, and -which, in the case of any of the ordinary varnishes, -would act as a fatal obstacle to perfect adhesion. To -make the cement, take half an ounce of Nelson’s opaque -gelatine, put in a small beaker, add sufficient cold -water to cover it, and allow the mixture to remain -until the gelatine has become thoroughly soaked. The -water is now poured off, and heat applied until the -gelatine becomes fluid, when three drops of creosote -should be well stirred in, and the fluid mixture transferred -to a small bottle to solidify. Before use, this -compound must be rendered liquid by immersing the -bottle containing it in a cup of warm water. When -the ring of gelatine has become quite set and dry (which -will not take long), every trace of glycerine must be -carefully removed from the cover and its neighborhood, -by gently swabbing these parts with a large camel’s-hair -pencil dipped in methylated spirit. After drying -the slide a ring of Bell’s microscopical cement may be -applied over the gelatine, and, when this is dry, another -coat is to be laid on. If it be desired to give the slide -a neat and tasteful appearance, it is a very easy matter, -by means of the turn-table, to lay on a final ring of -Brunswick black or white zinc cement (§ 24). Every -care has now been taken to render our preparation permanent; -but, to make assurance doubly sure, it will -be well to follow Dr. Carpenter’s advice, and, every -<span class='pageno' id='Page_42'>42</span>year or so, to lay on a thin coating of good gold-size.<a id='r12' /><a href='#f12' class='c013'><sup>[12]</sup></a></p> - -<div class='footnote c014' id='f10'> -<p class='c012'><a href='#r10'>10</a>. <span class='small'>The appearance of a slide is vastly improved if the preparation be -placed <i>exactly</i> in its centre. This may readily be done in the -following manner:—Take some very finely-powdered Prussian blue, and rub -it up in a mortar with a little of the weak gum solution (§ 11), so as -to form a thin blue pigment. A quantity of this should be made, so as -always to be at hand. A slide having been cleaned, the <i>best -surface</i> is to be selected, and on the <i>reverse</i> side, by means -of the self-centring turn-table, a small circle is to be drawn with a -camel’s-hair pencil, charged with the pigment. In the centre of this -ring, but on the opposite side of the slide, the section is to be -placed, when it of course will occupy a position exactly central. When -the slide comes to be finished, the blue ring may easily be removed -with a wet rag.</span></p> -</div> - -<div class='footnote c014' id='f11'> -<p class='c012'><a href='#r11'>11</a>. <span class='small'>A <i>crochet-needle</i> holder made of bone, and which may be -bought at the smallware dealers’ for about sixpence, makes an -admirable handle for microscopical needles. At one extremity -there is a small cavity, closed with a cap, for the storage of reserve -needles, whilst the other end terminates in a metal tip, -provided with a crucial slit and central perforation for the -reception of the needle in actual use, and so arranged that, by -means of a small screw-nut, needles of various sizes may be -firmly held in position.</span></p> -</div> - -<div class='footnote c014' id='f12'> -<p class='c012'><a href='#r12'>12</a>. <span class='small'>If square covers be employed, they may be fixed to the -slide by a simple method much in vogue in Germany. A thin -wax taper is to be lighted, and being partially inverted for a -few seconds, the wax surrounding the wick will become melted. -After the slide has been freed from excess of glycerine, a drop -of this heated wax is allowed to fall upon each corner of the -cover, and a line of the melted wax run along the margins of -the cover between these points, so as perfectly to surround it. -If a good coat of white zinc cement be subsequently laid over -the wax a very durable, and not unornamental, line of union will -have been formed.</span></p> -</div> - -<div class='figcenter id001'> -<img src='images/i_040.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>METHOD OF APPLYING COVER.</p> -</div> -</div> - -<p class='c012'><a id='p1-17'></a>17. <i>Use of Freezing Microtome.</i>—Our preceding -consideration of the method of employing the microtome -in conjunction with paraffine as an imbedding -agent (§ 11), will have formed a very suitable introduction -to the study of the somewhat more complicated -process of imbedding the tissue in gum, for section in -the freezing microtome. This method is of the utmost -value to the practical histologist, for by its means he is -enabled with ease to possess himself of perfect sections -of several structures, the cutting of which, before the -introduction of this process, was always a matter of -difficulty and anxiety. The freezing microtome is -especially valuable for the section of such substances -as from their extreme delicacy are liable to be injured -by being imbedded in paraffine—for instance, the delicate -villi of the intestines becomes very frequently, by -the use of paraffine, denuded of their epithelium, and -the villi themselves not seldom become torn off or otherwise -damaged. The great value of the method is also -very well seen in the treatment of those tissues which, -<span class='pageno' id='Page_43'>43</span>like the lung, are of such loose and spongy texture as -to offer insufficient resistance to the knife unless their -interstices have previously been filled up with some -solid yet easily cut material. As the space at our command -is strictly limited, we are precluded from entering -as fully into this branch of section-cutting as the -importance of the subject demands and our own inclination -would lead us. To those who wish to become -thoroughly conversant with the full value of this method -we cannot do better than recommend the perusal of -Professor Rutherford’s <i>Practical Histology</i>, 2d edition, -than which, on the whole subject of physiological -microscopy, no treatise with which we are acquainted -is at once so plain, practical, and profound.</p> - -<p class='c012'><a id='p1-18'></a>18. <i>Employment of Freezing Microtome.</i>—A very -suitable object with which to demonstrate the method -of using this form of microtome will be afforded us by -a portion of intestine, say of the ileum of a cat or dog. -Suppose we have some of this in methylated spirit—let -us select a piece of about half an inch in length. -Our first care will be to deprive this of its spirit; for -so long as the tissue remains impregnated with alcohol -it would, of course, be impossible to freeze it. We will, -therefore, throw it into a large basinful of water, and -leave it there for twenty-four hours, during which time -it would be as well to change the water once or twice. -We shall now require a strong solution of gum. This, -which should have been made some time previously, -may be prepared by placing a quantity, say three or -four ounces, of ordinary gum arabic in a glass beaker, -and adding sufficient water to cover it—the mixture -<span class='pageno' id='Page_44'>44</span>must be stirred occasionally with a glass rod until solution -has taken place, which will be in a few days. If -<i>necessary</i> a little more water may be added, but so long -as the gum will pour from vessel to vessel, it cannot -well be made too strong. Mucilage, by keeping, is very -apt to become sour and mouldy—this may be prevented -by adding to each ounce of the water with which it is -prepared about half a grain of salicylic acid. We now -pour some of this mucilage into a small vessel—an egg -cup will answer very well—and into it transfer the -piece of ileum from the water. Here we must allow it -to remain for a time sufficient to permit of its becoming -thoroughly saturated with the gum, for which purpose -some hours will be necessary. When this soaking -has been accomplished we will prepare the microtome, -which we will assume to be Rutherford’s. In the first -place it will be necessary to remove the plug—which is -to be done by turning the handle connected with the -screw until the plug rises so high in its tube that it -may be grasped with the fingers and removed, when it -is to be well smeared all over with sperm oil and replaced. -This is done to prevent any unpleasant adhesions -taking place whilst the freezing is going on. We -must next depress the plug, so as to convert the upper -part of the tube into a kind of “well” of sufficient -depth to hold our specimen. It will now be very advisable -to look carefully into this <i>well</i> and observe whether -the plug fits accurately into the tube (§ 8) for if there -be any interval between the two it will give rise to -much subsequent annoyance, as the gum penetrating -this interstice will there become firmly frozen into -<span class='pageno' id='Page_45'>45</span>irregular patches, which will so interfere with the even -gliding of the plug within its tube as to cause the -former to ascend in such an irregular and jerky manner -as to be utterly destructive of all accuracy in the cutting. -If this defect be observed, it may be at once -remedied by dropping a small quantity of gently heated -paraffine into the <i>well</i>, which will effectually close up -any fissures. The microtome, by means of its clamping -arrangement, must now be firmly attached to the -table, and a suitable vessel be placed on the floor beneath -it, so that it may catch the water which will -issue from the waste-pipe of the apparatus. The next -requirement is a supply of block ice and finely-powdered -salt. A lump of the ice must be wrapped in a towel, -and crushed into small pieces; these, by means of a -large mortar, are to be further reduced to a very <i>fine -powder</i>. Any attempt to hurry over this troublesome -part of the operation will lead to future disappointment, -for unless the ice be used in a very fine powder great -delay (at least) in the freezing will be the result. With -the aid of a small spoon the ice and salt are in alternate -spoonsful to be conveyed into the freezing-box of -the machine, great care being taken that the cavity -under the cutting-plate and around the tube be -thoroughly packed, after which the uncovered portion -of the box should also be well filled. The <i>well</i> is now -to be filled with the strong gum to within a little distance -of its top, and a piece of sheet gutta-percha (such -as shoe soles are made of) being applied over the well, -and kept in position by a weight, we must wait until -the freezing commences. In a short time we shall -<span class='pageno' id='Page_46'>46</span>notice that the gum has acquired a thick muddy appearance. -The tissue must now, by means of the forceps, -be transferred to the well, and there placed in -such a position that the sections, when cut, shall run -in the desired direction. After more gum has, if necessary, -been added, so as completely to cover the tissue, -the well is again to be covered, and attention given to -the freezing-box. As the mixture which this contains -becomes melted, it must constantly be renewed, care -being at the same time taken that the mouth of the -discharge-pipe be kept quite free, otherwise water -accumulating in the box, the freezing mixture will -degenerate into a useless puddle. When the gum becomes -sufficiently hard to cut, this must be done much -in the same manner as if paraffine had been used (§ 12). -In this case, however, no fluid will be required, or -must be used, to wet the knife with, and especial care -must be taken that in disengaging the sections from -the knife into the water they be not torn. These sections -often adhere very tenaciously to the blade, but if -a little patience be exercised the water will soon float -them off in safety—much more safely than if any -attempt be made to liberate them prematurely. There -is one circumstance connected with the use of the freezing -microtome which is rather annoying. The moisture -of the breath and atmosphere is apt to become -condensed on the cutting-plate, and here, mixed with -accidental smears of gum, it becomes frozen into a jagged -and irregular sheet of ice, which not only seriously -interferes with the smooth play of the knife, but also -constitutes a real peril to its edge. As this evil cannot -<span class='pageno' id='Page_47'>47</span>be avoided, all we can do is, by constant wiping, to -keep the cutting-plate clean and free from this accumulation. -This is best done with a bit of soft rag <i>just -moistened</i> with spirit, but this must not come into contact -with any portion of the cylinder of frozen gum, -else it will instantly thaw it. When using the freezing -microtome it is always advisable to wear an apron, -otherwise our clothes may receive considerable damage -from the constant splashing of the salt water, as it falls -from the waste-pipe into the vessel beneath it. After -use, the microtome must be well washed in plenty of -cold water till every trace of salt be removed, for if any -of this remain it will quickly corrode the brass-work of -the instrument. The plug and screw, as also the section-knife, -should be well smeared with Rangoon oil -before the machine is put away.</p> - -<p class='c012'><a id='p1-19'></a>19. <i>Logwood Staining.</i>—The employment of logwood -as a staining agent is now becoming very general. -It acts much in the same manner as carmine, but the -violet color which it produces is by many thought to -be of a more soft and agreeable character than that -due to the action of carmine. A valuable and very -convenient property also which it possesses is that it -stains tissues very rapidly, and this without interfering -with that differential kind of coloration (§ 14) upon -which the chief value of all staining processes depends. -A simple method of preparing the logwood fluid is to -mix an aqueous solution of extract of logwood with a -solution of alum (1 to 8) till the deep impure red colour -has become violet, and then to filter the mixture (Frey). -This will stain sections in about half an hour. This -<span class='pageno' id='Page_48'>48</span>stain, though here mentioned for the ease with which -it may be made is, as a rule, very inferior to a fluid -prepared directly from hæmatoxylon, the alkaloid or -active principle of logwood. As, however, it is difficult -and troublesome to make the solution in this -manner,<a id='r13' /><a href='#f13' class='c013'><sup>[13]</sup></a> it will be advisable for the student to purchase, -ready prepared, such small quantity of the dye -as he may require. Small bottles may be obtained for -a few pence of Mr. Martindale, 10, New Cavendish -Street, London, and from repeated trials of this solution -we can recommend it as producing excellent results. -It is a very strong fluid, and requires to be -diluted before use. The degree to which the dilution -must be carried cannot, however, be very accurately -indicated, for all staining fluids of this nature possess -the very undesirable property of becoming decomposed -by age. After the fluid has been kept for some time, -a portion of the colouring matter is thrown out of solution, -and becomes deposited upon the sides and bottom -of the vessel in which it is contained, hence the older -the preparation, the weaker it will have become. As -the time required for staining with logwood is but -short, it is desirable that all the sections should begin -to be submitted to its action at the same time, otherwise -some will become more deeply stained than others. -A good plan is to fill a small porcelain jar (§ 14) with -filtered water, and into this transfer the sections. -Whilst they are settling well down to the bottom, a -<span class='pageno' id='Page_49'>49</span>mixture must be prepared of half a drachm of Martindale’s -solution (fresh) to one ounce of distilled water, -and everything got in readiness for its immediate filtration. -The water is now very gently to be poured -off the sections, and if care be exercised this may be -done in such a manner as to leave them undisturbed -at the bottom, after removing almost every drop of -water. The diluted logwood fluid must now be <i>immediately</i> -filtered upon the sections, so that they may run -no risk of becoming dry. In the present instance the -staining may be allowed to proceed for about thirty -minutes, and this will be found a convenient time for -the immersion of the general run of animal sections. -If the logwood fluid be not quite fresh, either a little -more of it will have to be added to the water, or the -time of immersion must be prolonged until the desired -depth of color has been produced. It is well whilst the -staining is going on gently to shake the vessel occasionally, -so that the sections may not remain in a heap at -the bottom, but all be as fully as possible exposed to -the action of the dye. When the staining is judged to -be complete, the logwood solution must be gently -poured off, leaving the stained sections at the bottom -of the jar, when they should be quickly covered with -methylated spirit, which will <i>fix</i> the colour. We shall -now be able to see if the coloration obtained be perfectly -satisfactory. If not deep enough, it is very easy -again to submit them to the action of the dye for a few -minutes longer. If on the other hand, and as more -frequently happens, the coloration should be too deep, -the excess of colour may readily be removed by transferring -<span class='pageno' id='Page_50'>50</span>the sections for a short time into some diluted -acetic acid prepared by adding five drops of the glacial -acid to an ounce of water. The action of this should -be carefully watched, and when the colour has been -reduced to the desired tint the sections may be retransferred -to the methylated spirit.</p> -<div class='footnote c014' id='f13'> -<p class='c012'><a href='#r13'>13</a>. <span class='small'>Should the student, however, determine to prepare this -solution for himself, he will find a good formula for the purpose -in Schäfer’s “Practical Histology,” p 176. <a href='#N-i'>Note I.</a></span></p> -</div> - -<p class='c012'><a id='p1-20'></a>20. <i>Absolute Alcohol.</i>—As we purpose mounting -the sections which have just been stained, in Canada -balsam, we will briefly consider the preliminary treatment -to which they must be submitted before this can -be effected. The object of this is to abstract from the -tissue all its water, for if any moisture be permitted to -remain in the section it will, when mounted in balsam, -become obscured and surrounded by a kind of opalescent -halo, due to the imperfect penetration of the balsam -into the only partially dehydrated tissue. The -old-fashioned plan of dehydration was simple exposure -to the air. The method now generally adopted is to -bring about the same result by means of absolute -alcohol. This fluid has such a strong affinity for water -that tissues submitted to its influence are rapidly and -effectually deprived of any water they may contain. -Absolute alcohol in small quantity may be obtained -from the druggist at about sixpence per ounce. It will -be necessary for the student to provide himself with a -little of this agent, say about two ounces, the method -of using which will very shortly be explained. Absolute -alcohol must be kept in a bottle with a very accurately-fitting -stopper, in order to prevent its absorbing -moisture from the air. For our purpose such a bottle, -having a neck <i>as wide as possible</i>, is to be selected.</p> - -<p class='c012'><span class='pageno' id='Page_51'>51</span><a id='p1-21'></a>21. <i>Clove Oil.</i>—After being thoroughly dehydrated -the sections may, in special instances (§ 48), be at once -mounted in balsam; but, as a general rule, it will be -found necessary (particularly in the case of animal -sections) to treat them with some clarifying agent, in -order to remove the cloudiness and opacity which is -(in part) due to their previous immersion in alcohol. -For this purpose turpentine, or any of the essential -oils, may be used: of these, oil of cloves is to be specially -recommended. It is rather expensive, ranging -from sixpence to one shilling per ounce: but, as a drop -or two will be sufficient for preparing each slide, only -a small quantity—say half an ounce or an ounce—need -be procured. The most convenient vessel in which to -keep the oil is one of the small test bottles used by -watchmakers. These bottles are provided with a glass -cap to exclude dust, and the stopper is prolonged into -a glass rod, which dips into the bottle. The use of -this rod and the method of employing the oil will be -explained shortly.</p> - -<p class='c012'><a id='p1-22'></a>22. <i>Canada Balsam</i>, as ordinarily met with, is a -thick resinous balm of great viscidity, but readily rendered -perfectly fluid by the application of heat. -Formerly, sections were mounted in this medium in its -pure state, but owing to the annoyance which was so -constantly being experienced from the tenacity with -which intruding air-bubbles were held by the viscous -medium, this plan of mounting is rapidly falling out of -use.<a id='r14' /><a href='#f14' class='c013'><sup>[14]</sup></a> It is now usual to employ the balsam in a diluted -<span class='pageno' id='Page_52'>52</span>condition, the two chief diluents being chloroform -and benzole. As balsam, however, often contains -more or less moisture, it is desirable to drive this off -before adding the diluent. A very convenient way of -doing so is to expose some pure balsam to the heat of a -cool oven for several hours, when the balsam will be -found to have assumed a hard, vitreous character. It -should now be broken into small pieces, these put into -a bottle, and some methylated chloroform added, which -in a little while will completely dissolve the hardened -balsam. More chloroform is then to be added, until a -<span class='pageno' id='Page_53'>53</span>solution is obtained sufficiently thin to run through -filtering-paper. A glass spirit lamp must now be procured, -having a capacity of about two ounces, and -provided with a cap. Into the wick-holder of this -(which must be made of porcelain) a hollow glass tube -is to be so fitted that its end dips into the lamp to -within about a third of the bottom. (See Fig.) The -thin chloroform-balsam is now to be filtered into this -lamp, very fine filtering-paper—through which a little -chloroform has first been passed—being used for the -purpose. When the lamp is full it must (deprived of -its cap) be put in a warm place until sufficient of the -chloroform has evaporated to leave behind it a fluid of -the consistence of thin syrup.</p> -<div class='footnote c014' id='f14'> -<p class='c012'><a href='#r14'>14</a>. <span class='small'>Although we cannot too strongly insist upon the use of -chloroform-balsam wherever practicable, yet it sometimes happens -in the mounting of substances of <i>considerable thickness</i>, -that after all the chloroform has evaporated an insufficient -amount of balsam is left behind to fill up the cavity between -slide and cover. In such cases, therefore, it is advisable to use -pure balsam, which may be done in the following manner. The -object having been previously thoroughly dehydrated by immersion -in absolute alcohol, is to be thence transferred to a little -good turpentine, or benzole, where it should remain until perfectly -transparent. It is now to be placed in the centre of a -slide which has been gently warmed, and a drop or two of <i>fresh</i> -fluid balsam added, the greatest care being taken to prevent the -formation of air-bubbles. Should such arise they must be -touched with the point of a heated needle, which will cause -them to burst and disappear. The chief difficulty of the process -has yet to be encountered in the application of the cover; -for it is during this procedure that the development of air-bubbles -is most likely to take place. This annoyance may, -however, be entirely avoided by taking the simple precaution -of dipping the cover into turpentine before it is applied (§ 16), -when it will be found that “you can’t get air-bubbles, even if -you try.” The courtesy of Mr. J. A. Kay, of Chatham, enables -us to give our readers the benefit of this practical “<i>wrinkle</i>.”</span></p> -</div> - -<div class='figcenter id003'> -<img src='images/i_053.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>SPIRIT LAMP ADAPTED TO CONTAIN BALSAM.</p> -</div> -</div> - -<p class='c012'><a id='p1-23'></a>23. <i>Mounting in Balsam.</i>—Let us now return to our -sections which, it will be remembered, were left in -methylated spirit (§ 19). These we will now mount in -<span class='pageno' id='Page_54'>54</span>balsam, and although, of course, any number may be -proceeded with at the same time, yet to avoid confusion, -in the following directions one section only will -be spoken of. This section then is, with the perforated -spoon, to be transferred to the bottle of absolute alcohol, -where it may remain for about an hour—considerably -less time is <i>actually</i> required, but as from constant use -the spirit becomes weakened, it is as well to be on the -safe side. It must now be removed to the centre of a -clean glass slip, and here the <i>plain</i> end of the spoon -comes into use. If this be employed for effecting the -transfer, it will be found that when the section is being -removed from the alcohol it will bring along with it a -small pool of the spirit. A slight touch of the needle applied -to the edge of the section will cause it to float from -the spoon on to the slide, at the same time carrying -the pool of alcohol with it, in which it will gently spread -itself out upon the slide without the faintest risk of -injury. The superfluous spirit is now to be drained -off, and just as the section is becoming glazed and -sodden-looking (<i>not dry</i>) we must, by means of the -long glass stopper (§ 21), apply to it a large drop of -clove oil. The oil, however, should not be placed on -the section, but be allowed to drop on to the slide near -to its margin. By gently tilting the slide the oil will -gradually insinuate itself <i>beneath</i> the section and slowly -ascend through it to the surface. The slide should -now be covered with a bell-glass (or wine-glass), and -about two minutes allowed for the oil thoroughly -to saturate the section. As much as possible of the -superfluous oil must then be drained off, and the remainder -<span class='pageno' id='Page_55'>55</span>removed with blotting paper. By means of -the glass rod a small quantity of chloroform-balsam -is now taken from the spirit lamp which contains it, -and allowed gently to fall upon the section, which -must then be covered with a thin glass circle in the -manner previously described (§ 16). When the object -is very fragile, it is a good plan, after draining off the -clove oil, to apply the cover directly upon the section, -and then to place a drop of the balsam near to the edge -of the cover. This, by capillary attraction, will speedily -diffuse itself beneath the cover, flowing over and surrounding -the object, without in the slightest degree -disturbing its position. If, during the process of -mounting, any air-bubbles arise, we may view their development -with equanimity, being well assured that as -the chloroform evaporates they too will quickly disappear. -When the mounting is completed, the slide -should be roughly labelled and placed on a warm mantel-piece -for a few days to dry.</p> - -<p class='c012'><a id='p1-24'></a>24. <i>Finishing the Slide.</i>—In the course of two or -three days it will be advisable to take an old penknife, -and after heating the blade in the flame of a spirit lamp, -gently to run the point of it round the margin of the -cover, so as to remove any excess of balsam which may -have oozed from beneath it. In a few days more, any -remaining balsam may be carefully scraped away with -a cold knife. All remaining traces of balsam are then -to be removed from around the cover by means of a -rag <i>just moistened</i> with methylated spirit, or, what -is better, with a mixture of equal parts of spirit and -æther, after which the slide is to be thoroughly -<span class='pageno' id='Page_56'>56</span>washed in cold water. The slide is now in reality -finished, but, in order to give it a smart appearance, it -is usual, with the assistance of the turn-table, to run a -ring of colored varnish round the covering glass. A -very useful varnish for the purpose is the <i>white zinc -cement</i>. To prepare this, dissolve an ounce of gum -dammar in an ounce of turpentine by the aid of heat. -Take one dram of oxide of zinc and an equal quantity of -turpentine; rub them up together in a mortar, adding -the turpentine drop by drop, so as to form a creamy -mixture perfectly free from lumps or grit. One fluid -ounce of the dammar solution previously made must now -gradually be added, the mixture being kept constantly -stirred (<i>Frey</i>). The cement, when made, should be -strained through a piece of fine muslin, previously -wetted with turpentine, into a small wide-necked bottle, -which, instead of having a cork or stopper, should be -covered with a loose metal cap. Instead of a bottle, -the varnish may be kept in one of the collapsible tubes -used by artists; but though this plan is highly recommended -by many, it is not without its disadvantages. If -the varnish becomes thick by keeping, a few drops of -turpentine or benzole well stirred in will soon reduce -it to a suitable consistence for use.</p> -<div class='pbb'> - <hr class='pb c000' /> -</div> -<div class='chapter'> - <span class='pageno' id='Page_57'>57</span> - <h2 class='c005'>PART II.</h2> -</div> - -<p class='c006'><a id='p2-25'></a>25. <i>Special Methods.</i>—Having in the preceding -pages entered at some length into the general subject -of section-cutting, it remains for us now to consider -those special methods of preparation which the peculiarities -of certain objects demand. In order to keep -the bulk (and consequent price) of this manualette -within due bounds, we shall, without further preface, -proceed to the description of these methods, in doing -which every endeavour will be made to employ such -brevity of expression as may be consistent with perfect -clearness of meaning. As the most convenient plan, -the objects here treated of will be arranged in alphabetical -succession.</p> - -<p class='c012'><a id='p2-26'></a>26. <i>Bone.</i>—Both transverse and longitudinal sections -should be prepared, the former being the prettier -and most interesting. After prolonged maceration in -water, all fat, etc., must be removed and the bone -dried, when as thin a slice as possible is to be cut off in -the desired direction, by means of a very fine saw. If -the section so obtained be placed upon a piece of smooth -cork it may, with the aid of a fine file and the exercise -of care, be further reduced in thickness. It is then to -be laid upon a hone moistened with water, and being -pressed gently and <i>evenly</i> down upon it with the tip of -the finger (protected, if necessary, by a bit of cork or -<span class='pageno' id='Page_58'>58</span>gutta-percha), it must be rubbed upon the stone until -the desired degree of thinness has been attained. -Finally, in order to remove scratches and to polish the -section, it should be rubbed upon a dry hone of very -fine texture, or upon a strop charged with putty-powder. -After careful washing in several waters the -section must be allowed thoroughly to dry, when it -may be mounted by the <i>dry method</i> in the following -manner:—A ring of gold-size must, by means of the -turn-table, be drawn in the centre of a slide, and the -slide put away in a warm place for several days (the -longer the better), in order that the ring may become -perfectly dry and hard. When this has been accomplished -the section is to be placed in the centre of the -ring, and a covering circle of the requisite size having -been cleaned, this must have a <i>thin</i> ring of gold-size -applied round its margin. The cover is now to be -placed in position and gently pressed down, a spring -clip being employed, if necessary, to prevent it from -moving. In about twenty-four hours another layer of -the varnish should be applied, and the slide afterwards -finished in the manner already described (§ 24). The -above method is also applicable to the preparation of -sections of <i>teeth</i> and also of <i>fruit-stones</i> and other hard -bodies, which are incapable of being rendered soft -enough for cutting.</p> - -<p class='c012'>As the process just described, however, is both troublesome -and tedious, it is much better for ordinary purposes -to have recourse to the <i>decalcifying method</i>, by -which means sections in every way suitable for the -examination of the essential structure of bone may be -<span class='pageno' id='Page_59'>59</span>obtained with ease. To carry out this plan a piece of -fresh bone should be cut into small pieces and placed -in a solution made by dissolving 15 grains of pure -chromic acid in 7 ounces of distilled water, to which -30 minims of nitric acid s. g. 1.420 are afterwards to -be added. Here they should remain for three or four -weeks, or until the bone has become sufficiently soft to -cut easily, the fluid being repeatedly changed during -the process. From this solution they must be transferred -to methylated spirit for a few days, when a piece -may be selected, imbedded in paraffine, and cut in the -microtome (§ 12). Some of the sections should be -mounted, unstained, in spirit. For this purpose a cell -of gold-size, as above described, must first be prepared -and filled <i>full</i> of a mixture of spirit of wine one part, -and distilled water three parts. Into this the section -must be carefully placed and the cover applied, the -same precautions for the exclusion of air-bubbles being -taken which were recommended when speaking of -mounting in glycerine (§ 16). When the cover is in -position a ring of gold-size must be laid on, repeated -when dry, and the slide afterwards finished in the -ordinary manner. It will also be advisable to stain -some of the sections with carmine (§ 14), or picro-carmine -(§ 42), and mount them in glycerine. <i>Teeth</i> -may also be treated by the decalcifying method, but in -this case it must be remembered that the enamel will -dissolve away.</p> - -<p class='c012'><a id='p2-27'></a>27. <i>Brain.</i>—The best hardening fluid is that recommended -by Rutherford, and is made by dissolving -15 grains of pure chromic acid and 31 grains of crystalized -<span class='pageno' id='Page_60'>60</span>bichromate of potash in 43 ounces of distilled -water. Small pieces of brain, which have previously -been immersed for twenty-four hours in rectified spirit, -should be placed in about a pint of this solution, where -they must remain for five or six weeks, the fluid being -repeatedly changed during the process. If by this -time they are not sufficiently hard the induration must -be completed in alcohol. Sections are easily cut in the -microtome by the paraffine method (§ 12). These may -advantageously be stained in a solution of aniline blue, -made by dissolving 1-1/2 grain of aniline blue in 10 -ounces of distilled water, and adding 1 drachm of rectified -spirit (<i>Frey</i>). As this stain acts very rapidly -two or three minutes’ immersion will generally be -found long enough. The sections must then be -mounted in balsam (§ 23).</p> - -<p class='c012'><a id='p2-28'></a>28. <i>Cartilage.</i>—The method to be employed in the -preparation of cartilage will entirely depend upon the -nature of the staining agent, to the action of which the -sections are to be submitted. Thus, if the elegant <i>gold -method</i> is to be followed, it is necessary that the cartilage -should be perfectly fresh; whilst if any of the -other staining agents are to be employed the tissue may -have been previously preserved in alcohol. An excellent -object on which to demonstrate the gold process -is to be found in the articular cartilage of bone. It is -a very easy matter to obtain from the butchers the foot -of a sheep which has just been killed. The joint is to -be opened, and the bones dissociated, when they will -be seen to have their extremities coated with a white -glistening membrane—this is the <i>articular cartilage</i>. -<span class='pageno' id='Page_61'>61</span>Exceedingly thin slices must be at once cut from it, -and as only small sections are required, a sharp razor -may be used for the purpose, the blade being either -dry or simply wetted with distilled water. The sections -as cut are to be transferred to a small quantity of -a half per cent. solution of chloride of gold in a watch -glass. Chloride of gold may be purchased in small -glass tubes hermetically sealed, each tube containing 15 -grains, and costing about 2s. If, however, the student -requires only a small quantity of the staining fluid he -need not be even at this small expense, for as photographers -for the requirements of their art always keep -on hand a standard solution of chloride of gold of the -strength of one per cent., a little of this may readily be -obtained, and diluted to the required degree. After -the sections have been exposed to the action of the -staining fluid for about ten minutes they may be transferred -to a small beaker of distilled water, and exposed -to diffused light for about twenty-four hours, when -they must be mounted in glycerine (§ 16).</p> - -<p class='c012'>Sections of cartilage may also be examined, without -being stained, in which case the field of the microscope -should be only very feebly illuminated. Or carmine -staining (§ 14) may be resorted to—these sections show -well in glycerine, or if the staining be made very deep, -even Canada balsam may be employed, and with fair -results.</p> - -<p class='c012'>Microscopists are indebted to Dr. Frances Elizabeth -Hoggan for the description of a new method of staining, -which we have found especially suited to the -treatment of cartilage. The agent employed is <i>iron</i>, -<span class='pageno' id='Page_62'>62</span>and the process, which is very simple, is as follows. -Two fluids are necessary—(1) tincture of steel; (2) a -two per cent. solution of pyrogallic acid in alcohol. A -little of the former is to be poured into a watch glass, -and into this the sections, after having been previously -steeped in alcohol for a few minutes, are to be placed. -In about two minutes the iron solution is to be poured -away and replaced by solution No. 2. In the course -of a minute or two the desired depth of colour will have -been produced, when the sections are to be removed, -washed in distilled water, and mounted in glycerine. -The results obtained by this process are very beautiful, -the colour produced being a very fine neutral tint, of -delightful softness. The process also answers admirably -in the case of morbid tissues, and we have now in -our possession some sections of ulcerated cartilage -tinged by the iron method, in which the minute -changes resulting from the ulcerative disintegration are -brought out with wonderful distinctness.</p> - -<p class='c012'>As the structure of cartilage differs according to its -purpose and situation, the student will find his time -profitably employed in a careful examination of the following -forms (α) <i>hyaline</i>—articular and costal; (β) yellow -fibro-cartilage—epiglottis, or external ear; (γ) -<i>cellular</i>—ear of mouse. Sections of the <i>intervertebral</i> -ligaments should also be made, in which the different -kinds of cartilage may be examined side by side with -each other.</p> - -<p class='c012'><a id='p2-29'></a>29. <i>Coffee Berry</i> affords sections of great beauty. -The <i>unroasted</i> berry should be soaked for hours or days -in cold water until sufficiently soft; then imbedded in -<span class='pageno' id='Page_63'>63</span>paraffine, and cut in the microtome (§ 12), the section -being made in the direction of the long axis of the -berry. Put up in glycerine, or stain rather strongly -with carmine, and mount in balsam. The same -method of treatment may also be applied to other hard -berries or <i>seeds</i>.</p> - -<p class='c012'><a id='p2-30'></a>30. <i>Fat.</i>—Adipose tissue may be hardened in alcohol, -cut in paraffine, and mounted in glycerine. -If the tissue has been injected the sections may be -mounted in balsam, and are then very beautiful objects, -showing the capillary network encircling the fat -cells.</p> - -<p class='c012'><a id='p2-31'></a>31. <i>Hair.</i>—Longitudinal sections are readily made -by splitting the hair with a sharp razor. It is more -difficult to cut the hair transversely. This, however, -may easily be done in the following manner. The -hairs having previously been well soaked in æther to -remove all fatty matters, a sufficient number of them -must be selected to form a bundle about the thickness -of a crow quill. This bundle, after being tied at each -extremity with a bit of thread, is to be immersed for -several hours in strong gum (§ 18,) to which a few drops -of glycerine have been added. On removal, the bundle -must be suspended by means of a thread attached -to one end of it, in a warm place until sufficiently hard, -when it is to be imbedded and cut in paraffine (§ 12). -Each section, as cut, is to be floated off the knife into -methylated spirit. From this it is with the aid of the -spoon (§ 14) to be transferred to a slide, the spirit tilted -off, a drop of absolute alcohol added, when, after a -minute or two, this also is to be drained off, the -<span class='pageno' id='Page_64'>64</span>section treated with clove oil, and the mounting completed -as described in § 23.</p> - -<p class='c012'><a id='p2-32'></a>32. <i>Horn</i> varies very much in consistence, in some -instances having a cartilaginous character, whilst in -others it is almost bony. In the latter case, sections -will have to be ground down in the manner explained -when speaking of bone (§ 26). Where the texture is -less dense, recourse may be had to prolonged steeping -in hot or boiling water; in some cases it will be necessary -to continue the immersion for several hours. When -sufficiently soft the piece of horn may, by means of bits -of soft wood, be firmly wedged into the tube of the -microtome, and sections cut with a razor, or what is -better, with a broad and very sharp chisel. The sections -are to be put between glass slips, held together -by American clips (or pegs), and put away for two or -three days in order to become thoroughly dry. After -well soaking in good turpentine or benzole, they must be -transferred to slides, the superfluous turpentine drained -off, and chloroform-balsam added, etc. (§ 23). Sections -of horn should, of course, be cut in different -directions, but for examination with the polariscope -those cut transversely yield by far the most magnificent -results. <i>Hoofs</i>, <i>whalebone</i>, and allied structures -should also be treated by the above method.</p> - -<p class='c012'><a id='p2-33'></a>33. <i>Intestine.</i>—The method to be pursued with <i>sections</i> -has already been described (§ 18). The ileum, -however, is a very pretty object when a portion of it is -so mounted as to show the <i>villi erect</i>. To do this it is -necessary to cement to the slide, by marine glue, a glass -cell of sufficient depth. This should have been prepared -<span class='pageno' id='Page_65'>65</span>some time beforehand, so that the cement may -be perfectly dry and hard. The cell is now to be filled -with turpentine, and the piece of ileum (having been -previously passed through methylated spirit and absolute -alcohol into turpentine) is gently placed into it, -having the villi uppermost; pour some pure and rather -fluid balsam on the object at one end, and gradually -incline the slide, so as to allow the turpentine to flow -out at the opposite side of the cell, till it is full of balsam. -Then take a clean cover, and having placed upon -it a small streak of balsam from one end to the other, -allow it gradually to fall upon the cell, so as to avoid -the formation of air-bubbles (§ 17), and finish the slide -in the usual manner.<a id='r15' /><a href='#f15' class='c013'><sup>[15]</sup></a> Or, the intestine may be dried, -and mounted <i>dry</i>, in a cell with a blackened bottom, -for examination as an opaque object.</p> -<div class='footnote c014' id='f15'> -<p class='c012'><a href='#r15'>15</a>. <span class='small'>Ralf.</span></p> -</div> - -<p class='c012'><a id='p2-34'></a>34. <i>Liver.</i>—Small pieces of liver may be very successfully -hardened by immersion in alcohol, beginning -with weak spirit and ending with absolute alcohol. Cut -and mount as usual.</p> - -<p class='c012'><a id='p2-35'></a>35. <i>Lung</i> must be prepared in chromic acid (§ 5). -For the cutting of sections the freezing microtome -(§ 18) is of especial value, and should, therefore, be -used. If, however, the student be not provided with -this instrument, he must proceed as follows. A small -piece of lung, previously deprived of all spirit, is to be -immersed until thoroughly saturated in solution of gum -(§ 18). A small mould of bibulous paper (§ 2), only -just large enough to receive the piece of tissue, having -been prepared and filled with the mucilage, the specimen -<span class='pageno' id='Page_66'>66</span>is to be transferred to it. The mould, with its -contents, is now to be placed in a saucer, into which a -mixture of about 6 parts of methylated spirit and 1 part -of water (<i>Schäfer</i>) is to be poured until the fluid reaches -to within about a third of the top of the paper mould. -In the course of several hours the surface of the mucilage -will begin to whiten and solidify. As soon as this -occurs more dilute spirit must be poured into the saucer, -until the mould is completely submerged. In a day or -two the gum will be found to have acquired a suitable -consistence for cutting, when it must be removed from -the spirit, the paper mould peeled off, and the mass -imbedded and cut in paraffine, the sections being afterwards -treated as if they had been obtained by the freezing -method (§ 18). If the solidification of the gum -should proceed too slowly, a few drops of pure spirit -may be added to the contents of the saucer. If, on -the other hand, the gum should become overhard, it -will be necessary to put into the saucer a few drops of -water, and repeat this until the required consistence be -obtained.</p> - -<p class='c012'><a id='p2-36'></a>36. <i>Muscle.</i>—Harden in chromic acid, and cut in -paraffine. Transverse sections may be made to show the -shape of the fibrils. Longitudinal sections will only -be required in the case of injected tissues, when such -sections will be found very elegant, showing, as they -do, the elongated meshes of capillaries running between -and around the muscular fasciculi. Mount in glycerine -or balsam. To see the transverse striæ characteristic -of voluntary muscle, a very good plan is to take a bit of -pork (cooked or fresh), and by means of needles to -<span class='pageno' id='Page_67'>67</span>teaze it out into the finest possible shreds. If these be -examined in water or glycerine, the markings will be -shown very perfectly.</p> - -<p class='c012'><a id='p2-37'></a>37. <i>Orange-peel</i>, common object though it be, is not -to be despised by the microscopist. Transverse sections -must be prepared by the gum method (§ 35). -These sections are not to be subjected to the action of -alcohol (as this would destroy the colour), but after -<i>drying</i> between glass slides they must be soaked in -turpentine and mounted in balsam. We shall then -have a good view of the large globular glands whose -office it is to secrete that essential oil upon which the -odor of the orange depends.</p> - -<p class='c012'><a id='p2-38'></a>38. <i>Ovary</i> may be prepared in the same manner as -liver (§ 34). Sections, which are to be cut in paraffine, -may be stained with carmine, and mounted in glycerine -or balsam. Apart from all scientific value, we know -of no slide for the microscope which, even as a mere -object of show, surpasses in beauty a well-prepared section -of <i>injected</i> ovary, showing the wondrous Graafian -vesicles, surrounded by their meandering capillaries.</p> - -<p class='c012'><a id='p2-39'></a>39. <i>Porcupine Quill.</i>—Soften in hot water, cut in -paraffine, and mount in balsam. Much (in our opinion -<i>too</i> much) lauded as an object for the polariscope.</p> - -<p class='c012'><a id='p2-40'></a>40. <i>Potato.</i>—From the large amount of water which -it contains thin sections cannot be cut from the potato -in its natural state. It must, therefore, be partially -desiccated, either by immersion in methylated spirit for -a few days or by exposure to the air. Sections may -then readily be obtained by imbedding and cutting in -paraffine. Such sections mounted in balsam are very -<span class='pageno' id='Page_68'>68</span>beautiful, the starch being seen <i>in sitú</i>, whilst if polarized -light be employed each granule gives out its characteristic -black cross.</p> - -<p class='c012'><a id='p2-41'></a>41. <i>Rush</i> is to be prepared and cut as orange-peel -(§ 37). Transverse sections of this “weed” furnish -slides of the most exquisite beauty.</p> - -<p class='c012'><a id='p2-42'></a>42. <i>Skin.</i>—To prepare skin for section a piece is to -be selected which, after having been boiled for a few -seconds in vinegar, must be stretched out on a bit of -flat wood, and being maintained in position by pins be -allowed to remain until thoroughly dry. Then imbed -in paraffine, and cut <i>exceedingly</i> thin transverse sections. -These may be stained in carmine, but more -beautiful results are obtained if picro-carmine be employed. -Sections of skin, when stained by this agent -are much increased both in beauty and instructiveness; -for the several constituents of the tissue becoming -tinged with different colours are readily distinguishable -from each other, whilst the contrast of colouring forms a -pleasing picture to the eye. The method of preparing -picro-carmine is very simple, though it sometimes yields -a solution not altogether satisfactory. The best formula -with which we are acquainted is that given by Rutherford,<a id='r16' /><a href='#f16' class='c013'><sup>[16]</sup></a> -and if due care be taken in following it out failure -will generally be avoided. “Take 100 c.c. of a -saturated solution of picric acid. Prepare an ammoniacal -solution of carmine, by dissolving 1 gramme in a -few c.c. water, with the aid of excess of ammonia and -heat. Boil the picric acid solution on a sand bath, and -when boiling add the carmine solution. Evaporate -<span class='pageno' id='Page_69'>69</span>the mixture to dryness. Dissolve the residue in 100 c.c. -water, and filter. A clear solution ought to be obtained; -if not, add some more ammonia, evaporate, and dissolve -as before.” Sections may be exposed to the action -of this fluid for a period varying from fifteen to thirty -minutes, then rapidly washed in water, and mounted -in glycerine. They may also be mounted in balsam, -care being taken in that case to shorten as much as -possible the period of their immersion in alcohol, so that -no risk may be run of the picric acid stain being dissolved -out.</p> -<div class='footnote c014' id='f16'> -<p class='c012'><a href='#r16'>16</a>. <span class='small'>“Practical Histology,” 2d edit. p. 173.</span></p> -</div> - -<p class='c012'>If it is intended to study the structure of the skin -with anything like thoroughness, portions must of course -be examined from different localities, in order that -its several varieties and peculiarities may be observed. -Thus the <i>sudoriforous</i>, or sweat glands, may be found -in the sole of the foot, whilst the <i>sebaceous</i> glands are -to be sought in the skin of the nose. The <i>papillæ</i> are -well represented at the tips of the fingers,<a id='r17' /><a href='#f17' class='c013'><sup>[17]</sup></a> whilst the -structure of the shaft of the <i>hair</i>, together with that -of the follicle within which its root is enclosed, as also -the muscles by which it is moved, are to be studied in -sections of skin from the scalp or other suitable locality.</p> -<div class='footnote c014' id='f17'> -<p class='c012'><a href='#r17'>17</a>. <span class='small'>It is well, in connection with these papillæ, to bear in -mind a fact pointed out by <i>Frey</i>, namely, that the tips of the -fingers frequently become, <i>post-mortem</i>, the seat of extensive -natural injections; hence, in sections from this region, we frequently -obtain good views of distended capillaries without -having been at the trouble of previously injecting them.—<i>Frey</i>, -“Microscopical Technology.”</span></p> -</div> -<p class='c012'><a id='p2-43'></a>43. <i>Spinal Cord.</i>—The spinal cord, say of a cat -or -<span class='pageno' id='Page_70'>70</span>a dog (or if procurable, of man), after being cut into -pieces about half an inch in length, may be hardened -in the usual chromic acid fluid (§ 5). As it is peculiarly -liable to overharden and become uselessly brittle, -the process must be carefully watched. Its further -treatment is the same as that of brain. These sections -may be stained very satisfactorily by the <i>ink process</i>, -for communicating details of which we are indebted -to the kindness of Dr. Paul, of Liverpool. The -agent usually employed is Stephenson’s blue-black ink, -which, for this purpose, must be quite fresh. As in -the case of carmine, two methods of staining may be -adopted—either rapid, by using concentrated solutions, -or more prolonged, according to degree of dilution. -For the reasons previously given (§ 14), slow methods -of staining are always to be preferred, as yielding the -most beautiful results, yet, for the purposes of preliminary -investigation, it is often convenient to have -recourse to the quick process. To carry out the latter -plan, an ink solution of the strength 1 in 5—10 parts -of water is to be freshly prepared, and the sections exposed -to its action for a few minutes. For gradual -staining the dilution must be carried to 1 in 30—50, -and the time of immersion prolonged to several hours, -the sections being occasionally examined during the -staining, so that they may be removed just as they -have acquired the desired tint. When a satisfactory -coloration has been obtained, the preparations should -be mounted in dammar or balsam (§ 23). One advantage -of this method of staining is, that definition is -almost as good by artificial light as by day.</p> - -<p class='c012'><span class='pageno' id='Page_71'>71</span><a id='p2-44'></a>44. <i>Sponge</i> may readily be cut after being tightly -compressed between two bits of cork; or its interstices -may be filled up by immersion either in melted paraffine -(§ 11) or in strong gum (§ 18), and then cut as -usual.</p> - -<p class='c012'><a id='p2-45'></a>45. <i>Stomach</i> requires no special method of hardening -(chromic acid). Sections should always, when -practicable, be cut in the freezing microtome. In -default of this, proceed in the manner as directed for -lung (§ 35). Both vertical and horizontal sections will, -of course, be required. If the preparation has been -injected, the latter are particularly beautiful. Stain -with carmine or aniline blue (§ 27), and mount—if for -very close study, in glycerine—if injected and for a -“show” slide, use balsam.</p> - -<p class='c012'><a id='p2-46'></a>46. <i>Tongue.</i>—Harden in chromic acid, imbed and -cut transverse sections in paraffine. As, however, the -paraffine is apt to get entangled amongst the <i>papillæ</i>, -whence it is afterwards with difficulty dislodged, it will -be as well before imbedding to soak the tongue in -strong gum for a <i>few minutes</i>, and afterwards immerse -in alcohol till the gum becomes hardened, so that the -delicate papillæ may thus be protected from the paraffine -by a surface-coating of gum. The best staining -agent is picro-carmine (§ 42). Sections of <i>cat’s</i> tongue -near the root, when thus stained, furnish splendid -objects. Sections should also be made of the <i>taste-bulbs</i>, -found on the tongues of rabbits. These are small oval -prominences, situated one on each side of the upper -surface of the tongue near its root. They should be -snipped off with scissors, and vertical sections made in -<span class='pageno' id='Page_72'>72</span>the direction of their long axis. Stain with carmine -or picro-carmine, and mount in glycerine or balsam.</p> - -<p class='c012'><a id='p2-47'></a>47. <i>Vegetable Ivory</i>.—After prolonged soaking in -cold water may readily be cut in the microtome. The -sections should be mounted in balsam, and though not -usually regarded as polariscopic objects, nevertheless, -when examined with the <i>selenite</i>, yield very good -colours.</p> - -<p class='c012'><a id='p2-48'></a>48. <i>Wood.</i>—Shavings of extreme thinness may be -cut from large pieces or blocks of timber, by means of -a very sharp plane. In this way very good sections -may be procured of most of the common woods, as oak, -mahogany, “glandular wood” of pine, etc. Where -however, the material to be operated upon takes the -form of stems, roots, etc., of no great thickness, they -should, after having been reduced to a suitable consistence -(§ 4), be imbedded in paraffine, and cut in the -microtome. Before imbedding it must not be forgotten -to immerse the wood to be cut in weak gum-water -(§ 11), this precaution being of great importance, -especially in the case of stems, etc., the bark of which -is at all rough and sinuous. If the sections are to be -mounted <i>unstained</i>, they are usually put up in weak spirit -(§ 26). A very general method also of dealing with -this class of objects is to mount them <i>dry</i> (§ 26). This -plan, however, cannot be recommended, for however -thin the sections may be, the outlines, when this process -is adopted, always present a disagreeable black or -blurred appearance. To avoid this we may have recourse -to Canada balsam, but the ordinary method of -employing it must be slightly modified, a drop of chloroform -<span class='pageno' id='Page_73'>73</span>being substituted for the clove oil (§ 23), otherwise -this latter agent will cause the section to become -so transparent as to render minute details of structure -difficult to recognize. A better plan, perhaps, is to -stain the section with carmine or logwood, and mount -in balsam by the ordinary process. The best course to -follow, however, especially in the case of transverse -sections, is the <i>double staining</i> method.<a id='r18' /><a href='#f18' class='c013'><sup>[18]</sup></a> For this -purpose the sections in the first place must be subjected -to the action of a solution of chloride of lime -(1/4 oz. to a pint of water) until they become thoroughly -bleached. They must then be soaked in a solution -of hyposulphite of soda (one drachm to four ounces of -water) for an hour, and after being washed for some -hours, in several changes of water, are to be transferred -for a short time to methylated spirit. Some -red staining fluid is now to be prepared by dissolving -half a grain of Magenta crystals in one ounce -of methylated spirit. A little of this solution being -poured into a small vessel of white porcelain (§ 14), -the sections are to be immersed in the dye for about -thirty minutes. They are now to be removed, and -after <i>rapid</i> rinsing in methylated spirit to remove -all superfluous colour, they must be placed in a blue -staining fluid made by dissolving half a grain of aniline -blue in one drachm of distilled water, adding ten -<span class='pageno' id='Page_74'>74</span>minims of dilute nitric acid and afterwards sufficient -methylated spirit to make two fluid ounces. The sections -must be permitted to remain in this solution for -a very short time only, one to three minutes being generally -sufficient, for as the action of the dye is very -energetic, it will, if too long exposure be allowed, completely -obliterate the previous coloration by the magenta. -After being again <i>rapidly</i> rinsed in methylated spirit, as -much of this as possible must be drained off, and the -sections put into oil of <i>cajeput</i>, whence, in an hour, -they may be transferred to spirits of turpentine, and -after a short soaking, mounted in balsam.</p> -<div class='footnote c014' id='f18'> -<p class='c012'><a href='#r18'>18</a>. <span class='small'>See a paper by Mr. Styles in the “Pharmaceutical Journal,” -also “Monthly Microscopical Journal” for August, 1875. [For -a very exhaustive paper on this subject by the late Dr. Beatty, -of Baltimore, Md., see “American Journal of Microscopy” for -June, 1876.</span></p> -</div> - -<p class='c012'>If the student will carefully carry out the above -process, his trouble will be amply repaid by the beautiful -results obtained, for by its means he may, with -ease, prepare for himself a series of slides of such value -as to constitute a worthy addition to his cabinet.</p> - -<p class='c012'>The preceding list by no means represents all the -objects, sections of which will be found interesting to -the microscopic student. Such was not its purpose—had -it been so, the enumeration might have been prolonged -almost indefinitely. The end in view was to bring -under the notice of the reader only those substances -the cutting of which is accompanied by difficulty; and -even of this class the space at our disposal has been so -limited that we have been unwillingly compelled to -pass over many, and dwell only on such as possess a -typical character.</p> -<div class='pbb'> - <hr class='pb c000' /> -</div> -<div class='chapter'> - <span class='pageno' id='Page_75'>75</span> - <h2 class='c005'>NOTES.</h2> -</div> -<hr class='c015' /> -<h3 id='N-a' class='c016'>NOTE A., Page 14.</h3> - -<p class='c017'><span class='small'><span class='sc'>Rangoon</span> oil is not found in this market. It is a variety of -naphtha or petroleum found at Rangoon, in Asia, and contains a -variable percentage of solid paraffin. Kerosene with a very little -paraffin dissolved in it, would undoubtedly answer the same -purpose.</span></p> - -<p class='c012'><span class='small'>Good sperm oil or tallow (free from salt) will serve quite as -well. It is scarcely necessary to caution the reader that all oily -matter should be removed from the knife before it is used for -cutting sections. This is best effected by dipping it in hot water -and carefully wiping it.</span></p> - -<h3 id='N-b' class='c016'>NOTE B., Page 15.</h3> - -<p class='c017'><span class='small'><span class='sc'>Methylated</span> spirit is alcohol which contains a small -percentage of methyl. This renders it unfit for use in the manufacture -of liquors or even chloroform, but does not injure it as a preservative -fluid. The scientific men of Great Britain have the privilege of -obtaining this fluid free from duty, and consequently they make very -general use of it. In this country the student of science has no such -privilege, and must use the more expensive alcohol. This however is but -of a piece with other restrictions placed upon scientific pursuits in -this country, where men like Marshall Jewell and Hannibal Hamlin have -influence enough to pass laws which prohibit the exchange by mail of -microscopic specimens, which pass freely in every other civilized -country.</span></p> - -<p class='c012'><span class='pageno' id='Page_76'>76</span><span class='small'>True methyl alcohol, or methylated spirits, is not to be had -in this country, and therefore whenever this liquid is directed -to be used in English books the American microscopist must -substitute good alcohol. What is sold for “methyl alcohol” is -wood spirit or wood naphtha, and will not serve the purposes of -the microscopist, though it answers well enough for spirit -lamps, making varnishes, etc.</span></p> - -<h3 id='N-c' class='c016'>NOTE C., Page 20.</h3> - -<p class='c017'><span class='small'><span class='sc'>The</span> method described in the text is generally known as the -“free-hand” method, and although it is not generally employed -for the production of cabinet specimens or slides that are intended -for sale, yet it possesses so many advantages that every -student should endeavor to acquire the art of cutting sections -without the use of the microtome. For purposes of study such -sections are quite equal to the best of those usually found on -sale, and for the encouragement of beginners we may add that -we have seen sections cut by the free-hand method which for -size, thinness and accuracy, excelled any that we have ever seen -produced with the microtome. Indeed Schäffer distinctly affirms -that no microtome can equal the skilled hand in the production -of thin sections.</span></p> - -<h3 id='N-d' class='c016'>NOTE D., Page 22.</h3> - -<p class='c017'><span class='small'><span class='sc'>The</span> mere existence of a binding screw should be no -objection, and where bushings are employed it is sometimes necessary. -But as the author well observes, a binding screw cannot be used to -secure histological preparations.</span></p> - -<h3 id='N-e' class='c016'>NOTE E., Page 22.</h3> - -<p class='c017'><span class='small'><span class='sc'>A still</span> better system is where the section-knife is held in -a frame which slides on the plate so that the edge is kept just above -the surface. In this way the edge of the knife is never dulled by -grinding on glass or metal. A common mistake in this form, however, is -to raise the cutting edge too far above the surface of the plate. This -gives rise to great irregularities.</span></p> - -<div> - <span class='pageno' id='Page_77'>77</span> - <h3 id='N-f' class='c016'>NOTE F., Page 22.</h3> -</div> - -<p class='c017'><span class='small'><span class='sc'>As</span> the size of the sections which it may be desired to cut, -varies within wide limits, the best microtomes made in this -country are furnished with as many as three tubes or “bushings,” -fitting one within the other, and in this way the hole may -be partially filled up and thus reduced in size. This enables us -to obtain a range of from one inch and a quarter, suitable for -large histological preparations, to one-eighth of an inch for -such objects as hair sections.</span></p> - -<h3 id='N-g' class='c016'>NOTE G., Page 37.</h3> - -<div class='nf-center-c0'> -<div class='nf-center c000'> - <div>KNIVES FOR CUTTING SECTIONS.</div> - </div> -</div> - -<p class='c012'><span class='small'><span class='sc'>Success</span> in cutting sections depends more upon the excellence -of the knife that is used than upon any other one point, -and therefore the art of keeping the knife in good order is one -which should be acquired by every microscopist, even at the -cost of considerable time, study and labor. As a stepping stone -to the acquisition of this art, there are certain general principles -which must be thoroughly understood before we can hope for -success in practice. These principles are simple, and when once -clearly stated, quite obvious, but they are frequently overlooked.</span></p> - -<p class='c012'><span class='small'>Cutting instruments act in two ways—either as simple wedges or as a -series of wedges, the latter being generally known as the saw-like -action. It is frequently stated in school philosophies that the edges of -<i>all</i> cutting instruments are toothed like a saw, and that they act -like a saw; this is evidently not the case with many, such as the axe, -the chisel, the plane, etc., and it is not even true of several to which -it is frequently applied, such as the razor, the penknife, etc. The -action can be said to be “saw-like” only when the teeth act as -independent wedges and remove a small portion of the substance acted -upon, the portion being known as <i>saw-dust</i>. Now in cutting -sections of wood with a sharp razor, where but a single stroke is used -to carry the cutting edge across a section, say half an inch in -<span class='pageno' id='Page_78'>78</span>diameter, the edge of the razor does not act like a saw; none -of the material is removed except the section itself; in other -words, there is no saw-dust. That the edge of the knife or -razor is not even, is very easily proved by means of the microscope, -but it will be found that the notches and projections form -a series of lancet-shaped knifelets, each one of which acts just -as does the blade of a penknife when drawn over a piece of -wood or a quire of paper. Now if we lay a quire of paper on a -board and draw the edge of a penknife over it, we will cut down -through the paper, not by sawing but by a moving wedge. It is -precisely in this way that the little lancet-shaped teeth on the -edge of a razor act when the latter is used to cut a section.</span></p> - -<p class='c012'><span class='small'>If we further examine the edge of the razor, we will find -that the bottoms of the notches are comparatively blunt; if -therefore we press the razor directly forward we soon press -these blunt portions of the general edge against the material to -be cut, and the resistance becomes so great that the material is -actually crushed or torn. This would not happen if we had an -absolutely perfect edge—one without any notches. This being -practically unattainable, however, we must endeavor to make -up for it by a sawing motion, (though not a sawing action) at -the same time seeking to avoid as much as possible those saw-like -features which render this motion necessary. We have -dwelt at length upon this point because so much has been written -comparing the edge of a razor to that of a saw, that some -persons actually advise us to give the edges of our knives and -razors a saw-like character, under the impression that by so doing -they will work better. This is a fallacy; the best work will -be obtained from the smoothest and most perfect edge, provided -the latter is thin enough.</span></p> - -<p class='c012'><span class='small'>If the material of which our cutting instruments are made -would allow it, that is to say if it was perfectly hard, perfectly -rigid and incapable of being crushed or torn apart, the proper -shape of a cutting instrument would be a wedge of the most -acute form possible. But since the steel which we use is limited -in its hardness and its power of resisting crushing and -<span class='pageno' id='Page_79'>79</span>bending influences, the blades of our knives must have a certain -strength or thickness, depending upon the character of the material -to be cut. For very hard substances the knife must be -stout and the edge ground to a comparatively obtuse angle; -for moderately soft substances, such as wood, the angle may be -more acute, while for very soft tissues the thinnest blade and -the sharpest edge are most suitable.</span></p> - -<div class='figcenter id001'> -<img src='images/i_079a.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 1.</p> -</div> -</div> - -<p class='c012'><span class='small'>The various angles to which cutting tools of different kinds -are ground are shown in the accompanying illustrations, which -explain themselves.</span></p> - -<div class='figcenter id003'> -<img src='images/i_079b.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 2.</p> -</div> -</div> - -<p class='c012'><span class='small'>In the diagrams just given, the sides of the wedge are -carried in straight lines to the very edge. In practice, however, -this is never done, there being two strong objections to -such a form. In the first place if the sides were as shown in -the figures, every time the tool was ground or set, the entire -side would have to be ground off, and this would involve great -labor. But another difficulty, -quite as great, would occur in -the use of the instrument, for -since the wedge keeps growing -constantly and proportionately -thicker, the friction between -the sides of the wedge and the -material would rapidly become -very great. Therefore most -cutting edges are ground to a -second angle, much more obtuse -than the first, and it is -this second angle which forms -the true cutting edge. And it -<span class='pageno' id='Page_80'>80</span>is obvious that the mass of material required to carry out the -ultimate angle in any case is wholly unnecessary, for if the tool -be strong enough at <i>a b</i> (Fig. 2) it will certainly be strong -enough at <i>c d</i>. An extreme illustration of this principle is -shown in the cold chisel used for cutting iron, the edge of which -is shown in Fig. 2, and the angle of 80° to which it is ground -is carried out by dotted lines. The angle which the sides of -the chisel (not the sides of the extreme cutting edge however) -make with each other is 25°.</span></p> - -<div class='figcenter id004'> -<img src='images/i_080a.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 3.</p> -</div> -</div> - -<div class='figcenter id004'> -<img src='images/i_080b.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 4.</p> -</div> -</div> - -<p class='c012'><span class='small'>There are two methods by -which this change of angle -may be made, one of which is -shown in the cold chisel just -figured, and the other in the -razor of which a section is -shown in figures 3 and 4. In -the case of the cold chisel it -will be seen that the tool is -first formed to a thin straight -wedge which is afterwards -changed to one that is much -more blunt. This answers -very well where the ultimate -angle is comparatively large -or blunt, as is the case with -penknives, table-knives, carving-knives, -etc. But where the -ultimate angle is very small -this plan does not answer well, -and the method shown in Fig. -3 is generally adopted. Here the ultimate angle is such that lines -touching the extreme edge and the back of the blade are perfectly -straight and form the actual cutting angle. In this case, -therefore, the relief is obtained by hollowing out the sides of the -blade, and this is done to various extents, the extremes being -shown in figures 3 and 4. Fig. 3 shows a section of a razor -<span class='pageno' id='Page_81'>81</span>ground on a stone 12 inches in diameter, which is as large as is -generally used for this purpose. Fig. 4 is a section of a razor -ground on a four-inch stone—the smallest in general use. This -method of changing the angle is of course substantially the -same as the first, merely differing in the mechanical device -used, but it affords this important advantage that in the subsequent -honing and stropping processes the back of the razor -forms a perfect guide by which the ultimate angle may be determined. -This is not the case with the cold chisel or the -carving-knife, in both of which cases the eye and hand alone -determine the cutting angle, which is therefore apt to become -irregular or even rounded—the -worst form of all. This will be -more easily understood from -the following engravings -where A, Fig. 5, shows a penknife -blade, as applied to an -oilstone for the purpose of giving -it the final edge. The angle -here shown is considerably -greater than that generally used, but the principle is the same. -It is evident that if, in moving the blade back and forth on the -stone we allow it to rock or change the angle which the blade -makes with the stone’s surface, the edge will become rounded -as shown in Fig. 6—a form which for delicate work is useless.</span></p> - -<p class='c012'><span class='small'>If the blade be laid down flat as at B, Fig. 5, -the labor of wearing away the superfluous metal -will be enormous. But if the blade be hollow as -Fig. 7, (where the hollow is, for clearness of illustration, -slightly exaggerated) then the ultimate -angle may be formed quickly and accurately, -there being no danger of the angles being changed on account -of want of skill on the part of the operator.</span></p> - -<div class='figcenter id003'> -<img src='images/i_081a.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 5.</p> -</div> -</div> - -<div class='figcenter id003'> -<img src='images/i_081b.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 6.</p> -</div> -</div> - -<div class='figcenter id003'> -<img src='images/i_082a.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 7.</p> -</div> -</div> - -<div class='figcenter id005'> -<img src='images/i_082b.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 8.</p> -</div> -</div> - -<p class='c012'><span class='small'>In some cases one side is left quite flat and the other side is -ground to two or sometimes three angles, as in the carpenter’s -chisel, a section of which is shown in Fig. 8, where <i>a a</i> shows the -<span class='pageno' id='Page_82'>82</span>angle made by the body of the blade; <i>b b</i> the angle of the bevel -formed by the grindstone, and <i>c c</i> the angle of the cutting edge -which is formed by the oilstone. In this case the flat side -A B forms a straight guide and -enables the workman, in cutting, -to make straight, clean -work. In sharpening such a -tool on the oilstone the flat side -is always laid flat on the oilstone -and merely smoothed -off,<a id='r19' /><a href='#f19' class='c013'><sup>[19]</sup></a> and the skill of the workman -is chiefly shown in the -accuracy with which he forms the angle <i>c</i> B <i>c</i>. The dexterity -with which skilled workmen can effect this by the hand alone -is astonishing, but in the hands of those who -have had but little practice the edge infallibly -becomes rounded as shown in Fig. 6. Therefore -wherever a knife with a flat side is used, no attempt -should ever be made to grind this flat side -on the hone. Such an attempt will almost always -result in an edge so irregular that it will be -almost impossible to cut a good section with it. -But if the under side of the knife be left truly -flat, we will have the very best tool that can be -had for use with the microtome. Unfortunately, -however, it is very difficult to get a knife with a -truly flat surface, that is, one that is perfectly -“out of wind” as mechanics say. As a general -rule the flat sides of knives are not true planes but -irregularly curved surfaces; consequently when -laid on a plane surface, such as the table of a microtome, -they rock, and the edge is in contact with the table at some -points and separated from it at others, and the points which -<span class='pageno' id='Page_83'>83</span>are in contact change as the knife is moved diagonally across -the table. This makes the section irregular and worthless. -But a really good knife with a perfectly true flat side -is such a valuable tool that a good deal of effort may be profitably -expended in getting it, and when once obtained never let the flat -side be touched by a grindstone, or more than touched by a hone. -It is not absolutely necessary, however, that the sides of a delicate -knife should be curved, provided the knife is used for cutting -very soft materials. An angle of 10° or even 5° gives a -pretty stout blade when carried back three-quarters of an inch, -as may be seen by examining Fig. 1, and the guiding action of -the very thick back may be obtained by means of an artificial -guide, applied like the brass backs of tenon saws. Such an arrangement -is shown in Fig. 9, and has been found very effectual.</span></p> -<div class='footnote c014' id='f19'> -<p class='c012'><a href='#r19'>19</a>. <span class='small'>Holtzapffel tell us that chisels that are required for paring -across the end grain of moderately soft wood are considered to hang -better to the work when they have a very slight keen burr or wire edge -thrown up on the face or flat side of the tool. But this does not apply -to section knives.</span></p> -</div> - -<p class='c012'><span class='small'>When the knife -is to be honed, the -back is applied and -fastened by means -of two or three set -screws. When laid -on the hone, the -edge of the knife -and the lower surface of the back form the guide and regulate -the cutting angle. In this way we can use a broad, thin blade -and yet secure great accuracy in honing it. Such a blade has -this advantage also, that it is not so liable to be rounded and -thus injured by stropping as one in which the relief is obtained -by hollowing out the sides.</span></p> - -<div class='figcenter id003'> -<img src='images/i_083.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 9.</p> -</div> -</div> - -<p class='c012'><span class='small'>Such, then, are the general principles which govern the construction -of cutting tools, including the section knives used by -microscopists. We will now give a few practical directions for -selecting a knife and putting and keeping it in order.</span></p> - -<p class='c012'><span class='small'>In selecting a knife for cutting sections, regard must be had -to the texture of the material that is to be cut. To attempt to -cut delicate sections of soft tissues with the stout knives which -are suitable for cutting sections of woody fibre would be to destroy -<span class='pageno' id='Page_84'>84</span>the sections, while to reverse the operation and cut sections -of wood with thin, delicate knives would result in the -ruin of the knife. We have seen a most excellent knife seriously -injured by an attempt to cut material that was too hard -for it. The knife was very thin, and had proved most excellent -in cutting sections of such material as kidney, liver, etc. An -attempt was made, against our protest, to cut a section of an -apple-shoot, the wood of which was mature. Before the knife -had gone half way across, it bent, dug into the wood and -broke, leaving an ugly gap in the middle. Experienced section-cutters -know this very well, but young microscopists are not so -familiar with the facts just stated, and the point is too important -to be overlooked. Those, therefore, who devote themselves -to microscopical studies, or who expect to make sections -of materials of several kinds, differing in hardness, etc., -must provide themselves with knives of different degrees of -strength.</span></p> - -<p class='c012'><span class='small'>For common work, good razors are as good as anything, -provided they can be obtained with straight edges. Where -razors are not suitable, recourse must be had to the surgical -instrument maker, though we are sorry to say that there are -but few in this country that know how to forge, temper and -grind a decent knife. Most of our dealers in instruments do -not make the instruments they sell; they import the goods they -sell with their names stamped on, and thus get a reputation as -manufacturers; a special order they are unable to fill respectably. -There are some exceptions, but of the majority of dealers -what we have written above is true.</span></p> - -<p class='c012'><span class='small'>The points which specially demand attention in a knife for -cutting sections are these: 1. Quality of the steel used; 2. Temper; -3. Form of the blade.</span></p> - -<p class='c012'><span class='small'>Of the quality of the material of which a knife is made, -nothing can be determined except by actual trial. The old -tests of staining with acids, examining with the microscope, -etc., are worthless, or at least too crude and uncertain to be of -any practical value. Color changes with the degree of polish -<span class='pageno' id='Page_85'>85</span>that is produced, and, in short, there is no reliable guide. The -purchaser must depend entirely upon the reputation of the -manufacturer. There is plenty of good steel to be found; the -trouble lies with the cutlers. They are careless and in haste, -and as a consequence they burn the steel or fail to work it sufficiently, -and the result is a useless tool.</span></p> - -<p class='c012'><span class='small'>The steel may be of the very best quality, however, and well -forged, and yet the knife may fail from being badly tempered—too -soft or too hard. If too soft, the edge is soon dulled; the -knife requires to be frequently honed, and the time wasted in -keeping it in order is a serious drawback. If too hard, it is -impossible to give it a keen edge, for the metal crumbles away -as soon as it is honed or stropped very thin, and the edge becomes -ragged and dull. Good steel, well forged, may be so -tempered that it will neither crumble nor become rapidly dull.</span></p> - -<p class='c012'><span class='small'>Much may be learned on this point from careful inspection -of the edge, and trial on a piece of horn, such as an old razor -handle. When drawn over a clean piece of horn once or twice -the edge of a soft knife is completely dulled; if well-tempered -it should scarcely lose its keenness. Again, when laid flat on -the thumb nail and pressed, the edge ought to bend up without -breaking or crumbling, and at once, when the pressure is removed, -resume its original shape. The extent to which extreme -hardness and durability, or toughness, may be combined, -is well shown in the famous Toledo sword-blades. One of these -blades will shear through an iron nail without having its edge -perceptibly dulled, and yet so tough and springy is it that it -may be coiled up into a hoop of several folds without breaking -or receiving any permanent set. If we could only get section -knives of stuff like this, it would be a pleasure to work with -them.</span></p> - -<p class='c012'><span class='small'>After all, however, the only test of these two points, material -and temper, is a fair trial in actual practice. Of the form -of the blade, however, it is easy to judge, and there are a few -points which are frequently overlooked and which give rise to -errors that are attributed to other causes.</span></p> - -<p class='c012'><span class='pageno' id='Page_86'>86</span><span class='small'>In the text we are told that “It is essentially necessary that -the back and edge of the blade be strictly parallel to each -other.” The author undoubtedly knew what the correct form -should be, but the definition he has given is not a correct mathematical -statement of the conditions involved. These are as -follows:</span></p> - -<p class='c012'><span class='small'><i>The edge must form a straight line, and both the edge and the -under side of the back must lie in the same plane.</i></span></p> - -<p class='c012'><span class='small'>Let us consider these conditions somewhat carefully.</span></p> - -<p class='c012'><span class='small'>Since the hole in which the material to be cut is imbedded, is always -circular, and since the blade is generally pressed forcibly against the -table of the microtome, it is obvious that if the edge of the knife be -curved it will sink into the hole to a greater or less depth according -as it is further from the centre of the hole or nearer to it. To explain -this let us refer to the greatly exaggerated drawing given in figure 10 -where the edge of the knife, <i>a</i>, <i>b</i>, is shown in two -different positions covering the hole of the microtome. The least degree -of reflection will show that as the knife passes towards the centre from -<i>a b</i> to <i>aʹ bʹ</i>, it will have a tendency to turn on the back -as on a hinge, and the middle of the edge will sink deeper into the hole -as it approaches the centre of the latter. The section will therefore -vary in thickness and prove useless. This difficulty can be obviated -only by the use of a straight edge like <i>e f</i>, which will always -lie in the same plane.</span></p> - -<div class='figcenter id003'> -<img src='images/i_086.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 10.</p> -</div> -</div> - -<p class='c012'><span class='small'>If the knife were perfectly rigid, and the curved edge and -back lay entirely in the same plane, this difficulty would not -occur to any great extent. But since a curved edge rarely lies -wholly in the plane of the back of the knife, and since the -blades of most knives, especially those thin ones used for cutting -sections of soft tissues, yield a little to pressure, and since -<span class='pageno' id='Page_87'>87</span>this pressure is never exactly the same, it is impossible to prevent -irregularities from occurring.</span></p> - -<p class='c012'><span class='small'>While it is not necessary that the back of the knife and the -cutting edge should be parallel to each other, it is absolutely -necessary that they be in the same plane, or, as mechanics say,—“out -of wind.” If this condition be not observed, the blade -will rock on the microtome table as it passes over it, and irregularity -in thickness of section will result.</span></p> - -<p class='c012'><span class='small'>A slight knowledge of geometry will enable any one to see -that these statements are strictly accurate.</span></p> - -<p class='c012'><span class='small'>As regards other points in the form of the knife, we refer -to what has been previously said when discussing the general -principles which should govern the construction of cutting -tools.</span></p> - -<p class='c012'><span class='small'>We now proceed to give a few practical directions for sharpening -knives and razors and keeping them in order.</span></p> - -<p class='c012'><span class='small'>Section knives, during the process of sharpening, are subjected -to three distinct processes: 1, Grinding; 2, Honing; -3, Stropping.</span></p> - -<p class='c012'><span class='small'>Grinding is one of the most important, though it is probable -that it will rarely be undertaken by the microscopist himself. -More knives and razors are spoiled in grinding than in -any other way. We have now in our possession an excellent -knife, which in an evil hour we entrusted to a New York cutler, -and received it back utterly ruined, the temper being entirely -taken out of the blades! Some of our readers may wonder at -this, but unfortunately it is too true. The cutler, to save time -and trouble, too frequently holds the blade against the stone -with such force that it becomes over-heated, especially when he -is a little careless and allows the supply of water to fall short.<a id='r20' /><a href='#f20' class='c013'><sup>[20]</sup></a> -The owner does not find this out until he discovers that the -knife is ruined, because nothing is more easy than to cool the -blade and grind off the tell-tale blue spots. When charged -with his rascality, the cutler always denies it and lays the blame -<span class='pageno' id='Page_88'>88</span>on a “soft spot in the steel”—a miserable subterfuge—too transparent -to deceive the least experienced.</span></p> -<div class='footnote c014' id='f20'> -<p class='c012'><a href='#r20'>20</a>. <span class='small'>Nothing is more easy than to heat a thin rod or stout wire red hot by -holding it against a dry grindstone rapidly revolving. We have often -kindled fire in this way.</span></p> -</div> - -<p class='c012'><span class='small'>The only protection against this is either to entrust the knife -to a man of known carefulness and integrity, or to stand over -him while he does it. If the knife be ground under the owner’s -eye, no fear need be entertained, because it is easy to insist upon -the use of plenty of water.</span></p> - -<p class='c012'><span class='small'>The grindstone used for section knives should be of fine -grain, and it should run true and be very straight across the face, -otherwise it will be impossible to grind the knife true, and this, -as we have seen, is a necessity.</span></p> - -<p class='c012'><span class='small'>Every microscopist that expects to do much at cutting sections -must learn to hone his own knife or razor. Of the various -hones in use the famous Turkey oilstone is said to be altogether -the best. It is, however, very difficult to get it genuine -and in sufficiently large pieces. We therefore use the German -hone-slate, a softer, yellow stone of wonderful fineness and cutting -power. The ordinary whetstones are altogether too coarse, -and as for artificial stones and strops, they may do for coarse -work and common razors for <i>scraping</i>, but they will not do for -knives used for section-cutting. If any of our readers should -be so fortunate as to possess a good, old-fashioned Turkey oilstone -with a fair sized surface, let them think much of it. It -is invaluable. Years ago, when working on some investigations -that required the use of very sharp knives, we were offered, by -an old English carpenter, the use of a real Turkey stone. We -have never since found anything that did its work so quickly -and so well.</span></p> - -<p class='c012'><span class='small'>To merely mention the substitutes for Turkey oilstone -would fill some pages. We therefore confine ourselves to the -German hone. It is obtained from the slate mountains in the -neighborhood of Ratisbon, where it occurs in the form of a -yellow vein running vertically into the blue slate, sometimes -not more than an inch in thickness, and varying to twelve to -eighteen inches. After being quarried it is sawed into thin -slabs, which are usually cemented to a similar slab of the blue -<span class='pageno' id='Page_89'>89</span>slate as a support, and the combined stones are then set in a -wooden frame and fitted with a cover, also of wood. Unlike -the Turkey oilstone, the Arkansas stone, and some others, the -German hone is soft and easily scratched and worn. It must -therefore be carefully preserved, and as the <i>flatness</i> of the hone -is an important point, it should never be used for anything but -section knives.</span></p> - -<p class='c012'><span class='small'>Having purchased a hone, the first thing to do is to see that -it is perfectly true; that is, that its surface is a perfect plane. -If hollow or twisted, it is useless until made straight. It may -be tested by means of two steel or wood straight-edges, and the -method of doing this, which is very simple but difficult to describe, -the microscopist can learn from any cabinet maker or -carpenter. If the hone be not true it must be made so, and this -is best done by grinding it with emery on a slab of marble or, -better still, a plate of cast iron which has been planed true. -(Waste castings with planed surfaces may be found in most -machine shops, and may be either borrowed or purchased for a -small sum.) If the hone is very uneven, coarse emery may be -used at first; then finer must be taken, and so on until the surface -of the hone is not only true but very smooth. This involves -considerable labor, but it cannot be avoided if a <i>true</i> edge as -well as a sharp one is desired, and hence our advice to use the -hone for nothing but section knives. Accuracy in a penknife -or a razor for shaving is of no consequence; in a section-knife -it is a <i>sine qua non</i>.</span></p> - -<p class='c012'><span class='small'>The surface of the hone must not only be true and smooth, -it must also be clean and free from dust and grit, a single particle -of which may spoil the work of hours. It should therefore, -when not in use, be kept constantly covered. It is always -used with oil, and this oil should be of a kind that does not -readily dry up. Good sperm is excellent, and so is purified -neat’s-foot oil. Avoid kerosene, soap and water, and similar -fluids, which are so frequently recommended, especially under -the guise of new discoveries. They have all been tried and -found wanting. After use, the stone should be carefully wiped -<span class='pageno' id='Page_90'>90</span>clean, fresh oil being applied when it is next used. It must -never be used without a liberal supply of oil, otherwise it will -become glazed and will no longer act on the steel.</span></p> - -<p class='c012'><span class='small'>The hone being in good order, the blade is laid flat on it -and moved over its surface with circular sweeps. The method -of doing this is easily acquired, and is best learned by watching -an expert cutler at work. If we could only hit it, the perfection -of this operation would be to wear down the sides of the -blade until they just met; they would then form a keen and -perfect edge. Unfortunately we cannot always hit this point -exactly; we are apt to overdo the matter just a little, and then -comes up the <i>bête noir</i> of beginners—the “wire edge.” This -is caused by the metal of the blade bending away from the hone -as soon as it becomes of a certain degree of thinness. Once it -does this it cannot be worn off by the hone, and the only way to -remove it is to draw the edge of the knife or razor across a -piece of horn or hard wood. After removing the wire edge in -this way, give the blade one or two sweeps on the hone and -then strop it. If the blade be very soft, the wire edge comes -very quickly and easily, and is very hard to get rid of. On very -hard blades the wire edge is not so apt to make its appearance. -It comes, however, on very excellent blades. It may be avoided -in a measure by driving the blade edge-first over the hone, and -indeed the blade should always be sharpened most in this way. -And since the backward and forward strokes are always nearly -equal, as regards space passed over, this is accomplished by exerting -a greater pressure on the forward than on the backward -stroke.</span></p> - -<p class='c012'><span class='small'>This wire edge is a nasty thing when it breaks off on the -hone. Unless removed it will very speedily ruin a fine knife, -therefore look out for it and wipe off the hone carefully if you -have any suspicion that particles of steel have broken off the -blade and got on to it.</span></p> - -<p class='c012'><span class='small'>In honing, as in everything else, however, nothing but -practice will impart skill, and he who intends to become an -expert should practice on a few old razors, grinding, honing -<span class='pageno' id='Page_91'>91</span>and stropping them himself, until he has acquired the art of -giving them an edge far keener than most of the razors ordinarily -used for shaving.</span></p> - -<p class='c012'><span class='small'>The last operation to which the knife is subjected is that of -stropping, and as the blade should be stropped after every section, -it becomes important that our tools should be good and -that we should know how to use them. By having two or -three knives we can always avoid grinding and honing the -blades ourselves, for it is then easy to hire the work done, and -half a dozen knives will last a careful worker a long time with -merely the aid of a good strop. But the strop he must use -himself. Fortunately no great skill is required in stropping, -but the strop must be a good one and is best home-made.</span></p> - -<p class='c012'><span class='small'>Our readers have doubtless seen the “Cheap John” strop-vendors -take a rough table knife, strop it on one of their “patent” -strops and cut a hair with it. Nevertheless such a knife, -sharpened in that way, would not cut good sections, and such a -strop is not just the thing for giving the finishing touch to a -section-knife, even though the label does say that it is “intended -for surgical instruments.”<a id='r21' /><a href='#f21' class='c013'><sup>[21]</sup></a></span></p> - -<div class='footnote c014' id='f21'> -<p class='c012'><a href='#r21'>21</a>. <span class='small'>The finest emery paper, glued on a strip of wood and used as a strop, -will impart to a razor an edge sufficiently keen to enable it to remove -the beard, and if paper three or four degrees coarser be used, a very -dull knife or razor may be sharpened, and afterwards stropped on the -finer emery until it is keen enough to cut a hair. But it will be found -that cutting edges produced in this way are not smooth enough for -section-cutting.</span></p> -</div> - -<p class='c012'><span class='small'>The strop should never be used with the intention of removing -metal so as to thin the edge of the knife. This is the -proper function of the hone, and those who depend most on the -hone and least on the strop, will always succeed best. The -strop is used in the first place for <i>smoothing</i> off the edge, and -in the second for removing that incipient dullness which always -comes from even the slightest use. It is true that in the -latter case the strop trespasses somewhat on the functions of -the hone, but only to a very slight extent, and stropping should -never be carried so far as to require more than a very few -strokes.</span></p> - -<div class='figcenter id003'> -<span class='pageno' id='Page_92'>92</span> -<img src='images/i_092a.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 11.</p> -</div> -</div> - -<div class='figcenter id003'> -<img src='images/i_092b.jpg' alt='' class='ig001' /> -<div class='ic001'> -<p>Fig. 12.</p> -</div> -</div> - -<p class='c012'><span class='small'>The best material for a strop is good calf-skin, well tanned, -and firmly glued to a strip of wood with the hair side out. The -leather should be hard, otherwise it will rapidly round the edge -of the knife. The way in -which this occurs is readily -understood from figures 11 -and 12. In Fig. 12 the leather -is seen to rise up behind -the edge of the blade as the latter passes over it, so that instead -of two plane facets meeting at an angle of from 15° to 20° as -left from the hone, (Fig. 12) the edge has become considerably -rounded and the ultimate angle -of the cutting edge is nearly -or quite doubled. The hardest -and firmest leather should -therefore be chosen, avoiding -of course any leather that has -been made hard and unpliable -by the action of water or other agents. Two sides will be found -enough for a strop. On one the leather should be kept clean, -while the other should be thoroughly impregnated with fine -grained, but very hard rouge or crocus.<a id='r22' /><a href='#f22' class='c013'><sup>[22]</sup></a> Rouge is an artificial -oxide of iron prepared by exposing sulphate of iron to heat. -The hardness of the resulting powder depends upon the temperature -to which it has been exposed, and this temperature is -very well indicated by the color which the rouge assumes. -Bright red or crimson rouge is soft and will not cut steel; hard -rouge, suitable for polishing steel, is purple in color, and this -quality should therefore be chosen. Great care should be taken -to see that it is free from gritty particles, and it should be well -rubbed into the leather in a dry state. All mixtures of grease -and oil with abrasive substances should be eschewed. If the -leather be of good texture and the rouge hard and fine, a very -<span class='pageno' id='Page_93'>93</span>few strokes will suffice to impart the last degree of smoothness -and keenness to the blade.</span></p> -<div class='footnote c014' id='f22'> -<p class='c012'><a href='#r22'>22</a>. <span class='small'>Rouge may be purchased from dealers in watch-makers’ tools. Those -who cannot procure it readily may very easily prepare it for themselves. -Full directions may be found in the “Amateur’s Handbook.” New York: -Industrial Publication Company.</span></p> -</div> - -<p class='c012'><span class='small'>Since grit and dust would soon spoil the strop, it should be -kept carefully covered and protected. The rouge will require -occasional renewing, which may be done by sprinkling a little -lightly over the surface and rubbing it in with the finger. -Consequently we find that the best and most convenient holder -for rouge is a bottle with some fine but porous fabric tied over -the mouth of it, forming as it were a sort of dredge. Over the -bottle mouth and its cover should be tied a paper cap to keep -out dust.</span></p> - -<p class='c012'><span class='small'>We have thus endeavored to give, in as simple a manner as -possible, such information as will guide the microscopist to the -acquisition of skill in this most important but generally despised -department of his art. We are told by the biographer -of Swammerdam that a great deal of his success was to be attributed -to his skill in sharpening his fine knives and scissors. -The same is also stated of other noted workers, and yet none -give even the slightest directions to the novice who desires to -follow in their footsteps. There is not to our knowledge a single -book in the English language which treats fully of this subject, -with perhaps the exception of Holtzapffel’s work on “Mechanical -Manipulation,” and this has long been out of print. -As previously stated, however, it is only by practice that the -necessary finger-skill can be acquired, but this skill is well -worth acquiring at any cost. The man who depends upon cutlers -and knife grinders will never make satisfactory progress.</span></p> - -<h3 id='N-h' class='c016'>NOTE H.</h3> - -<p class='c017'><span class='small'>We are inclined to believe that the difficulty of enclosing -glycerine does not arise from the dissolving action of this liquid, -so much as from the great adhesiveness which exists between -it and glass. Oily cements are of course attacked by glycerine, -but shellac and several other gums are insoluble, and drying -oils, if well oxidized are also insoluble. Where cells are used -<span class='pageno' id='Page_94'>94</span>they must be first firmly attached to the clean slide, and the -cement should also be brought into direct contact with the -clean cover. Glycerine does not evaporate at ordinary temperatures, -and consequently wherever the slide or cover is soiled -with it, no cement will ever adhere until the glycerine has been -wiped off. There is no prospect of its drying.</span></p> - -<h3 id='N-i' class='c016'>NOTE I. Page 48.</h3> - -<p class='c017'><span class='small'>The solution here referred to, and which is known as Kleinenberg’s -solution, is made in the following way:</span></p> - -<p class='c012'><span class='small'>(1.) Make a saturated solution of crystallized calcium chloride -in 70 per cent. alcohol, and add alum to saturation. (2.) Make -also a saturated solution of alum in 70 per cent. alcohol. Add -(1) to (2) in the proportion of 1:8. To the mixture add a few -drops of a saturated solution of hæmatoxylin in absolute alcohol.</span></p> - -<p class='c012'><span class='small'>This solution may be used in very many cases for staining -sections, in place of the ordinary watery solution of logwood -alum. It may, if required, be diluted with the mixture of 1 and -2. The stained sections are placed at once in strong spirit.</span></p> -<div class='pbb'> - <hr class='pb c000' /> -</div> -<div class='chapter'> - <span class='pageno' id='Page_95'>95</span> - <h2 id='index' class='c005'>INDEX.</h2> -</div> - -<ul class='index c003'> - <li class='c018'>Acetic acid, <a href='#Page_38'>38</a></li> - <li class='c018'>Adipose tissue, <a href='#Page_63'>63</a></li> - <li class='c018'>Æther microtome, <a href='#Page_24'>24</a></li> - <li class='c018'>Air-bubbles, <a href='#Page_40'>40</a>, <a href='#Page_55'>55</a>, <a href='#Page_62'>62</a></li> - <li class='c018'><a id='alcohol'></a>Alcohol, <a href='#Page_17'>17</a>, <a href='#Page_19'>19</a> - <ul> - <li>absolute, <a href='#Page_54'>54</a></li> - </ul> - </li> - <li class='c018'>Balsam, Canada, <a href='#Page_46'>46</a>, <a href='#Page_51'>51</a> - <ul> - <li>to clean from slide, <a href='#Page_55'>55</a></li> - </ul> - </li> - <li class='c018'>Beale’s carmine fluid, <a href='#Page_33'>33</a></li> - <li class='c018'>Bell’s cement, <a href='#Page_41'>41</a></li> - <li class='c018'>Blue staining fluid, <a href='#Page_60'>60</a></li> - <li class='c018'>Bone, <a href='#Page_16'>16</a>, <a href='#Page_57'>57</a> - <ul> - <li>decalcified, <a href='#Page_58'>58</a></li> - </ul> - </li> - <li class='c018'>Bottles for media, &c., <a href='#Page_48'>48</a></li> - <li class='c018'>Brain, <a href='#Page_59'>59</a></li> - <li class='c018'>Brunswick black, <a href='#Page_41'>41</a></li> - <li class='c018'>Capillary attraction, <a href='#Page_55'>55</a></li> - <li class='c018'>Carmine staining, <a href='#Page_32'>32</a></li> - <li class='c018'>Carpenter, Dr., <a href='#Page_37'>37</a>, <a href='#Page_41'>41</a></li> - <li class='c018'>Cartilage, <a href='#Page_60'>60</a></li> - <li class='c018'>Cells, to make, <a href='#Page_59'>59</a></li> - <li class='c018'>Centring slide, <a href='#Page_38'>38</a></li> - <li class='c018'>Chloroform-balsam, <a href='#Page_51'>51</a>, <a href='#Page_54'>54</a></li> - <li class='c018'>Chromic acid, <a href='#Page_17'>17</a></li> - <li class='c018'>Clove oil, 51, <a href='#Page_54'>54</a></li> - <li class='c018'>Coffee berry, <a href='#Page_62'>62</a></li> - <li class='c018'>Cover, applying, <a href='#Page_37'>37</a> - <ul> - <li>German plan, <a href='#Page_39'>39</a></li> - </ul> - </li> - <li class='c018'>Crochet-needle holders, <a href='#Page_39'>39</a></li> - <li class='c018'>Double staining, <a href='#Page_73'>73</a></li> - <li class='c018'>Dry mounting, <a href='#Page_58'>58</a>, <a href='#Page_65'>65</a>, <a href='#Page_72'>72</a></li> - <li class='c018'>Fat, <a href='#Page_63'>63</a></li> - <li class='c018'>Finishing slide, <a href='#Page_54'>54</a></li> - <li class='c018'>Fibro-cartilage, <a href='#Page_62'>62</a></li> - <li class='c018'><span class='pageno' id='Page_96'>96</span>Freezing method, <a href='#Page_42'>42</a>-<a href='#Page_47'>47</a></li> - <li class='c018'>Fresh tissues, to cut, <a href='#Page_15'>15</a>-<a href='#Page_17'>17</a></li> - <li class='c018'>Fruit stones, <a href='#Page_58'>58</a></li> - <li class='c018'>Gardner, Mr., <a href='#Page_25'>25</a>, <a href='#Page_31'>31</a></li> - <li class='c018'>Gelatine cement, <a href='#Page_41'>41</a></li> - <li class='c018'>Glycerine, 37, <a href='#Page_38'>38</a></li> - <li class='c018'>Gold staining, <a href='#Page_58'>58</a></li> - <li class='c018'>Gum, imbedding in, <a href='#Page_22'>22</a>, <a href='#Page_66'>66</a> - <ul> - <li>strong, <a href='#Page_43'>43</a></li> - <li>weak, <a href='#Page_31'>31</a>, <a href='#Page_71'>71</a></li> - </ul> - </li> - <li class='c018'>Hair, <a href='#Page_63'>63</a>-<a href='#Page_69'>69</a></li> - <li class='c018'>Hæmatoxylon, <i>see</i> <a href='#logwood'>Logwood</a></li> - <li class='c018'>Hand-sections, <a href='#Page_19'>19</a></li> - <li class='c018'>Hardening agents, <a href='#Page_19'>19</a></li> - <li class='c018'>Hoggan, F. Elizabeth, Dr., <a href='#Page_61'>61</a></li> - <li class='c018'>Hone, <a href='#Page_26'>26</a>, <a href='#Page_57'>57</a></li> - <li class='c018'>Horn, hoofs, &c., <a href='#Page_16'>16</a>, <a href='#Page_64'>64</a></li> - <li class='c018'>Hyaline cartilage, <a href='#Page_62'>62</a></li> - <li class='c018'>Ice, for freezing, <a href='#Page_43'>43</a></li> - <li class='c018'>Injections, to harden, <a href='#Page_19'>19</a></li> - <li class='c018'>Ink staining, <a href='#Page_70'>70</a></li> - <li class='c018'>Intestine, <a href='#Page_42'>42</a>, <a href='#Page_43'>43</a>, <a href='#Page_64'>64</a></li> - <li class='c018'>Iron staining, <a href='#Page_61'>61</a></li> - <li class='c018'>Kay, J. A., Mr., <a href='#Page_52'>52</a></li> - <li class='c018'>Kidney, <a href='#Page_17'>17</a></li> - <li class='c018'>Klein’s <i>lifter</i>, <a href='#Page_35'>35</a></li> - <li class='c018'>Knife, section, 25, <a href='#Page_30'>30</a></li> - <li class='c018'>Leaves, &c., to cut, <a href='#Page_12'>12</a></li> - <li class='c018'>Ligaments, intervertebral, <a href='#Page_62'>62</a></li> - <li class='c018'>Lime, carbonate of, <a href='#Page_37'>37</a></li> - <li class='c018'>Liver, <a href='#Page_65'>65</a></li> - <li class='c018'><a id='logwood'></a>Logwood staining, <a href='#Page_47'>47</a></li> - <li class='c018'>Lung, <a href='#Page_43'>43</a>, <a href='#Page_65'>65</a></li> - <li class='c018'>Martindale’s logwood fluid, <a href='#Page_47'>47</a></li> - <li class='c018'><span class='pageno' id='Page_97'>97</span>Media, mounting, <a href='#Page_38'>38</a></li> - <li class='c018'>Methylated spirit, <i>see</i> <a href='#alcohol'>Alcohol</a></li> - <li class='c018'><a id='microtome'></a>Microtome, <a href='#Page_21'>21</a> - <ul> - <li>choice of, <a href='#Page_22'>22</a></li> - </ul> - </li> - <li class='c018'>Microtome, employment of, <a href='#Page_29'>29</a> - <ul> - <li>freezing, <a href='#Page_43'>43</a>, <a href='#Page_44'>44</a></li> - <li>imperfection in, <a href='#Page_23'>23</a>, <a href='#Page_46'>46</a></li> - <li>Rutherford’s, <a href='#Page_31'>31</a></li> - </ul> - </li> - <li class='c018'>Muscle, <a href='#Page_66'>66</a></li> - <li class='c018'>Needles, microscopical, <a href='#Page_39'>39</a></li> - <li class='c018'>Orange-peel, <a href='#Page_67'>67</a></li> - <li class='c018'>Ovary, <a href='#Page_67'>67</a></li> - <li class='c018'>Papillæ of finger, <a href='#Page_69'>69</a></li> - <li class='c018'>Paraffine, adhering to sections, <a href='#Page_27'>27</a> - <ul> - <li>imbedding in, <a href='#Page_20'>20</a>, <a href='#Page_26'>26</a></li> - <li>mixture, <a href='#Page_26'>26</a></li> - <li><i>rising</i> in tube, <a href='#Page_23'>23</a></li> - <li>shrinks in cooling, <a href='#Page_29'>29</a></li> - </ul> - </li> - <li class='c018'>Paul, Dr., <a href='#Page_70'>70</a></li> - <li class='c018'>Pathological specimens, <a href='#Page_19'>19</a>, <a href='#Page_62'>62</a></li> - <li class='c018'>Picro-carmine, <a href='#Page_59'>59</a>, 68, <a href='#Page_72'>72</a></li> - <li class='c018'>Porcupine quill, <a href='#Page_67'>67</a></li> - <li class='c018'>Potato, <a href='#Page_67'>67</a></li> - <li class='c018'>Preparation of animal tissues, <a href='#Page_16'>16</a> - <ul> - <li>vegetable tissues, <a href='#Page_15'>15</a></li> - </ul> - </li> - <li class='c018'>Prussian blue pigment, <a href='#Page_38'>38</a></li> - <li class='c018'>Rangoon oil, <a href='#Page_14'>14</a>, <a href='#Page_47'>47</a></li> - <li class='c018'>Razors, <a href='#Page_20'>20</a>, <a href='#Page_26'>26</a>, <a href='#Page_29'>29</a>, <a href='#Page_30'>30</a></li> - <li class='c018'>Rush, <a href='#Page_78'>78</a></li> - <li class='c018'>Rutherford’s microtome, <a href='#Page_24'>24</a>, <a href='#Page_31'>31</a> - <ul> - <li>“Practical Histology,” <a href='#Page_43'>43</a></li> - </ul> - </li> - <li class='c018'>Salicylic acid, <a href='#Page_44'>44</a></li> - <li class='c018'><span class='pageno' id='Page_98'>98</span>Salt, for freezing, <a href='#Page_45'>45</a></li> - <li class='c018'>Schäfer’s “lifter,” <a href='#Page_35'>35</a> - <ul> - <li>“Practical Histology,” <a href='#Page_48'>48</a></li> - </ul> - </li> - <li class='c018'>Scissors, section, <a href='#Page_13'>13</a></li> - <li class='c018'>Sebaceous glands, <a href='#Page_69'>69</a></li> - <li class='c018'>Section-cutter, <i>see</i> <a href='#microtome'>Microtome</a></li> - <li class='c018'>Section-knife, <a href='#Page_24'>24</a></li> - <li class='c018'>Sections, thickness of, <a href='#Page_31'>31</a> - <ul> - <li>to dehydrate, <a href='#Page_52'>52</a></li> - <li>to transfer, <a href='#Page_33'>33</a></li> - </ul> - </li> - <li class='c018'>Seeds, <a href='#Page_63'>63</a></li> - <li class='c018'>Skin, <a href='#Page_68'>68</a></li> - <li class='c018'>Sperm oil, <a href='#Page_44'>44</a></li> - <li class='c018'>Spinal cord, <a href='#Page_69'>69</a></li> - <li class='c018'>Spirit lamp for balsam, <a href='#Page_53'>53</a> - <ul> - <li>weak, <a href='#Page_36'>36</a>, <a href='#Page_59'>59</a></li> - </ul> - </li> - <li class='c018'>Sponge, <a href='#Page_71'>71</a></li> - <li class='c018'>Spoon, section, <a href='#Page_35'>35</a>, <a href='#Page_54'>54</a></li> - <li class='c018'>Staining agents, <a href='#Page_31'>31</a></li> - <li class='c018'>Strop, razor, <a href='#Page_26'>26</a>, <a href='#Page_29'>29</a></li> - <li class='c018'>Stomach, <a href='#Page_71'>71</a></li> - <li class='c018'>Sudoriferous glands, <a href='#Page_69'>69</a></li> - <li class='c018'>Taste-bulbs, <a href='#Page_71'>71</a></li> - <li class='c018'>Teeth, 16, <a href='#Page_58'>58</a></li> - <li class='c018'>Tongue, <a href='#Page_71'>71</a></li> - <li class='c018'>Tubes, collapsible, <a href='#Page_56'>56</a></li> - <li class='c018'>Valentin’s knife, <a href='#Page_14'>14</a></li> - <li class='c018'>Vegetable ivory, <a href='#Page_72'>72</a> - <ul> - <li>tissues, to prepare, <a href='#Page_12'>12</a></li> - </ul> - </li> - <li class='c018'>Vessels, porcelain, <a href='#Page_33'>33</a></li> - <li class='c018'>Water-bath, cheap, <a href='#Page_29'>29</a></li> - <li class='c018'>Whalebone, <a href='#Page_64'>64</a></li> - <li class='c018'>White zinc cement, <a href='#Page_56'>56</a></li> - <li class='c018'>Wood, <a href='#Page_72'>72</a></li> -</ul> -<div class='pbb'> - <hr class='pb c000' /> -</div> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div><span class='pageno' id='Page_101'>101</span><span class='xlarge'><b>CATALOGUE</b></span></div> - <div class='c000'>OF</div> - <div class='c000'><span class='xlarge'>Books and Periodicals</span></div> - <div class='c000'>PUBLISHED AND FOR SALE BY</div> - <div class='c000'><span class='large'>THE INDUSTRIAL PUBLICATION COMPANY,</span></div> - <div class='c000'><i>176 Broadway, New York</i>.</div> - </div> -</div> - 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Price 75 cents.</span></p> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div><span class='xlarge'>HOW TO USE THE MICROSCOPE.</span></div> - <div class='c000'>A Simple and Practical Book, intended for beginners.</div> - <div class='c000'><span class='sc'>By</span> JOHN PHIN,</div> - <div class='c000'><i>Editor of “The American Journal of Microscopy.”</i></div> - <div class='c000'>Second Edition. Greatly Enlarged, with 50 illustrations in the text,</div> - <div>and 4 full-page engravings printed on heavy tint paper.</div> - <div class='c000'><span class='large'>CONTENTS:</span></div> - </div> -</div> - -<p class='c019'><span class='sc'>What a Microscope is.</span>—Different Kinds of Microscopes.—Simple -Microscopes.—Hand Magnifiers.—The Coddington Lens.—The Stanhope Lens.—Raspail’s -Microscope.—The Excelsior Microscope.—Twenty-five cent Microscopes and how to -make them.—Penny Microscopes.</p> - -<p class='c019'><span class='sc'>Compound Microscopes.</span>—Different kinds of Objectives.—Non-Achromatic -Objectives.—French Achromatic Objectives.—Objectives of the English -Form.—Immersion Objectives.—Focal Lengths corresponding to the numbers -employed by Nachet, Hartnack and Gundlach.</p> - -<p class='c019'><span class='sc'>How to Choose a Microscope.</span>—Microscopes for Special Purposes.—Magnifying -Power required for different purposes.—How to judge of the -quality of the different parts of the Microscope.</p> - -<p class='c019'><span class='sc'>Accessory Apparatus.</span>—Stage Forceps, Animalcule Cage, etc.</p> - -<p class='c019'><span class='sc'>Illumination.</span>—Sun Light.—Artificial Light.—Bulls-Eye Condenser.—Side -Reflector.—The Lieberkuhn.—Axial Light.—Oblique Light.—Direct -Light.</p> - -<p class='c019'><span class='sc'>How to Use the Microscope.</span>—How to Care for the Microscope.</p> - -<p class='c019'><span class='sc'>How to Collect Objects.</span>—Where to find Objects.—What to Look -for.—How to Capture Them.—Nets.—Bottle-Holders.—Spoons.—New Form of -Collecting Bottle.—Aquaria for Microscopic Objects.—Dipping Tubes.</p> - -<p class='c019'><span class='sc'>The Preparation and Examination of Objects.</span>—Cutting Thin -Sections of Soft Substances.—Sections of Wood and Bone.—Improved -Section-Cutter.—Sections of Rock.—Knives.—Scissors.—Needles.—Dissecting -Pans and Dishes.—Dissecting Microscopes.—Separation of Deposits from -Liquids.—Preparing whole Insects.—Feet, Eyes, Tongues, Wings, etc., of -Insects.—Use of Chemical Tests.—Liquids for Moistening -Objects.—Refractive Power of Liquids.—Covers for Keeping out -Dust.—Errors in Microscopical Observations.</p> - -<p class='c019'><span class='sc'>Preservation of Objects.</span>—General Principles.—Recipes for -Preservative Fluids.—General Rules for Applying them.</p> - -<p class='c019'><span class='sc'>Mounting Objects.</span>—Apparatus and Materials for: Slides, Covers, -Cells, Turn-Table, Cards for Making Cells, Hot-Plate, Lamps, Retort -Stand, Slide-Holder, Mounting Needles, Cover Forceps, Simple Form of -Spring Clip, Centering Cards, Gold-Size, Black Japan, Brunswick Black, -Shellac, Bell’s Cement, Sealing Wax Varnish, Colored Shellac, Damar -Cement, Marine Glue, Liquid Glue, Dextrine.—Mounting Transparent Objects -Dry.—Mounting in Balsam.—Mounting in Liquids.—Mounting of Whole -Insects.—How to Get Rid of Air-Bubbles.—Mounting Opaque Objects.</p> - -<p class='c019'><span class='sc'>Finishing the Slides.</span></p> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div>May be obtained from any Bookseller or News Agent, or will be sent by</div> - <div>mail, postage paid, on receipt of price.</div> - <div class='c000'><span class='large'>THE INDUSTRIAL PUBLICATION COMPANY,</span></div> - <div class='c000'>P. 0. Box 4875. 176 Broadway, New York.</div> - </div> -</div> - -<div class='pbb'> - <hr class='pb c000' /> -</div> - -<div class='nf-center-c1'> -<div class='nf-center c004'> - <div><span class='pageno' id='Page_107'>107</span><i>GENESIS AND GEOLOGY.</i></div> - </div> -</div> - -<hr class='c023' /> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div>THE CHEMICAL HISTORY</div> - <div class='c000'>OF</div> - <div class='c000'><span class='xlarge'>The Six Days of Creation.</span></div> - <div class='c000'>BY JOHN PHIN, C. E.,</div> - <div class='c000'><span class='sc'>Editor of “The American Journal of Microscopy.”</span></div> - <div class='c000'><i>1 Vol., 12mo.</i> <i>Cloth.</i> <i>75 cents.</i></div> - </div> -</div> - -<hr class='c023' /> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div>The following are a few of the Opinions of the Press:</div> - </div> -</div> - -<p class='c019'>This is a small book, but full of matter. * * * We think this book is -full of interest and value; and as the discussions concerning the harmony -of science and faith are rife at the present day, we commend the reasonings -of Mr. Phin to the great number of readers and students who are -investigating these subjects.—<i>The Presbyterian</i> (Philadelphia).</p> - -<p class='c019'>The author gives a new solution of this difficult question, and certainly -presents many very plausible arguments in support of his theory.—<i>Sunday-School -Workman.</i></p> - -<p class='c019'>A very candid and ingenious essay.—<i>Christian Union</i> (H. W. Beecher’s -paper).</p> - -<p class='c019'>No one can read this book without compensation, without becoming -more thoughtful concerning the phenomena of creation; and he need -lose none of his reverence for the supremacy of the Divine Law.—<i>Rural -New Yorker.</i></p> - -<p class='c019'>We could say much in commendation of Prof. Phin’s little book. An -intelligent reader can hardly fail to be interested in it, and many might be -benefited.—<i>Country Gentleman.</i></p> - -<p class='c019'>The book can not fail to interest even those who do not fully accept the -theory it advocates.—<i>Boston Journal of Chemistry.</i></p> - -<p class='c019'>It is a new scientific view of the matter.—<i>Phrenological Journal.</i></p> - -<p class='c019'>The book, although not large, will prove exceedingly interesting to all -who have ever directed attention to this matter, and contains more solid -and suggestive thought than many voluminous treatises on the subject.—<i>Insurance -Monitor.</i></p> - -<p class='c019'>The work is ingenious and original, and presents many striking suggestions.—<i>American -Baptist.</i></p> - -<p class='c019'>We believe Prof. Phin has started upon the correct basis, and his theory -is mainly tenable. His views are presented in a manner which, though -terse, is easily comprehended.—<i>Daily Guardian</i> (Paterson, N. J.)</p> -<div class='pbb'> - <hr class='pb c000' /> -</div> - -<div class='nf-center-c1'> -<div class='nf-center c004'> - <div><span class='pageno' id='Page_108'>108</span><span class='xlarge'>THE YOUNG SCIENTIST,</span></div> - <div class='c000'><span class='large'>A Practical Journal for Amateurs.</span></div> - <div class='c000'><b>ISSUED MONTHLY. Price 50 Cents per year.</b></div> - </div> -</div> - -<p class='c019'>It is characteristic of young Americans that they want to be <span class='fss'>DOING</span> -something. They are not content with merely <i>knowing</i> how things are done, -or even with <i>seeing</i> them done; they want to do them themselves. In other -words, they want to experiment. Hence the wonderful demand that has sprung up -for small tool chests, turning lathes, scroll saws, wood carving tools, -telegraphs, model steam engines, microscopes and all kinds of apparatus. In nine -cases out of ten, however, the young workman finds it difficult to learn how to -use his tools or apparatus after he has got them. It is true that we have a -large number of very excellent text-books, but these are not just the thing. -What is wanted is a living teacher. Where a living teacher cannot be found, the -next best thing is a live journal, and this we propose to furnish. And in -attempting this, it is not our intention to confine ourselves to mere practical -directions. In these days of knowledge and scientific culture, the “Why” becomes -as necessary as the “How.” The object of the <span class='sc'>Young Scientist</span> is to give -clear and easily followed directions for performing chemical, mechanical and -other operations, as well as simple and accurate explanations of the principles -involved in the various mechanical and chemical processes which we shall -undertake to describe.</p> - -<p class='c019'>The scope and character of the journal will be better understood from an inspection -of a few numbers, or from the list of contents found on a subsequent -page, than from any labored description. There are, however, three features to -which we would call special attention:</p> - -<p class='c019'><span class='sc'>Correspondence.</span>—In this department we intend to place our readers in -communication with each other, and in this way we hope to secure for every one -just such aid as may be required for any special work on hand.</p> - -<p class='c019'><span class='sc'>Exchanges.</span>—An exchange column, like that which has been such a marked -success in the <i>Journal of Microscopy</i>, will be opened in the Young Scientist. -Yearly subscribers who may wish to <i>exchange</i> tools, apparatus, books, or the -products of their skill, can state what they have to offer and what they want, -<i>without charge</i>. Buying and selling must, of course, be carried on in the -advertising columns.</p> - -<p class='c019'><span class='sc'>Illustrations.</span>—The journal will make no claims to the character of a -“picture book,” but wherever engravings are needed to make the descriptions -clear they will be furnished. Some of the engravings which have already appeared -in our pages are as fine as anything to be found in the most expensive journals.</p> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div>Special Notice.</div> - </div> -</div> - -<p class='c019'>As our journal is too small and too low-priced to claim the attention of news -dealers, we are compelled to rely almost wholly upon subscriptions sent directly -to this office. As many persons would no doubt like to examine a few numbers -before becoming regular subscribers, we will send four current numbers as a -trial trip for</p> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div>FIFTEEN CENTS.</div> - </div> -</div> - -<hr class='c023' /> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div><span class='xlarge'>CLUBS.</span></div> - </div> -</div> - -<p class='c019'>Where three or more subscribe together for the journal, we offer the following -liberal terms:</p> - -<table class='table2' summary=''> -<colgroup> -<col width='68%' /> -<col width='31%' /> -</colgroup> - <tr> - <td class='c024'>3 copies for</td> - <td class='c011'>$1.25</td> - </tr> - <tr> - <td class='c024'>5 〃 〃</td> - <td class='c011'>2.00</td> - </tr> - <tr> - <td class='c024'>7 〃 〃</td> - <td class='c011'>2.75</td> - </tr> - <tr> - <td class='c010'>10 〃 〃</td> - <td class='c011'>3.50</td> - </tr> -</table> - -<p class='c019'>Advertisements, 30 cents per line.</p> - -<p class='c019'>As postal currency has nearly disappeared from circulation, we receive postage -stamps of the lower denominations (ones, twos and threes) at their full value. -Postal orders are, however, much safer and more convenient. To avoid delay -and mistakes address all communications to “<span class='sc'>The Young Scientist</span>, Box 4875, -New York,” and make all checks and orders payable to John Phin.</p> -<div class='pbb'> - <hr class='pb c000' /> -</div> - -<div class='nf-center-c1'> -<div class='nf-center c004'> - <div><span class='pageno' id='Page_109'>109</span><b>WHAT PEOPLE SAY OF US.</b></div> - </div> -</div> - -<p class='c019'>In a letter to the Editor, Oliver Wendell Holmes, the genial “Autocrat -of the Breakfast Table,” says: “I am much pleased with the <span class='sc'>Young -Scientist</span>. It makes me want to be a boy again.”</p> - -<p class='c019'>“It is a little publication, calculated to call out and educate all the -latent ingenuity and thirst for knowledge which the youthful mind possesses, -and we hope it will win its way into every household in the land.”—[Scientific -Press.</p> - -<p class='c019'>“We have never seen a periodical, designed for youth, which came -nearer to our ideal of what such a journal should be.”—[Canadian -Pharmaceutical Journal.</p> - -<p class='c019'>“The <span class='sc'>Young Scientist</span> is one of the choicest publications for juvenile -minds in this country. Every page treats on subjects of importance to -young and old, portrayed in a clearly comprehensive manner, which at -once interests the young idea in its careful perusal.”—[Lapeer Clarion.</p> - -<p class='c019'>“It seems to fill the bill.”—[Newport Daily News.</p> - -<p class='c019'>“It is pleasing to note that its youthful subscribers will not be misled -by clap-trap advertisements or advertisements of patent medicines, which -will not be received at any price. The <span class='sc'>Young Scientist</span> is doing good -work in setting its face against this class of humbugs.”—[Manufacturing -and Trade Review.</p> - -<p class='c019'>“The work is a copiously illustrated monthly, and is full of practical -hints that will instruct and amuse the young folks.”—[Industrial School -Advocate.</p> - -<p class='c019'>“A small but elegant and very instructive monthly.”—[Pittsburg -Chronicle.</p> - -<p class='c019'>“Contains the best possible reading for the young of both sexes.”—[Ottawa -Journal.</p> - -<p class='c019'>“We can safely recommend this magazine as one of the very best -publications for the young folks.”—[The Independent, Fenton, Mich.</p> - -<p class='c019'>“This journal occupies a new field, and is needed to put the minds of -our youth on the right track to secure a correct understanding of the -nature of things.”—[Wayland Press.</p> - -<p class='c019'>“It is ably edited by John Phin, who will make a large place in the -heart of the rising generation, if he persists in his venture. We hope his -success in the field will be equal to the article furnished—first best.”—[Sunset -Chimes.</p> - -<p class='c019'>“The articles are written in a popular, readable style, and profusely -illustrated.”—Akron City Times.</p> - -<p class='c019'>“The <span class='sc'>Young Scientist</span> is excellent in conception, and well designed to -amuse and instruct young people.”—[Chicago Evening Journal.</p> - -<p class='c019'>“The <span class='sc'>Young Scientist</span> is a handsome monthly magazine, each number -containing about 16 pages, handsomely illustrated. It will supply a -place which has been heretofore unoccupied. The copy before us comes -fully up to the promise of the prospectus.”—[The Times, Iroquois, Mich.</p> - -<p class='c019'>“It is a journal which should be in the hands of both young and old, -and is a great benefit to the young scientist as well as the advanced professor. -It is a thousand times more valuable than the dime novel series, -so much read by boys. Parents would do well to have it in their households.”—[The -Iron Home.</p> - -<p class='c019'>“This publication is a new launch, and it is very gratifying to witness -the ableness which pervades its pages.”—Amherst Free Press.</p> -<div class='pbb'> - <hr class='pb c000' /> -</div> - -<div class='nf-center-c1'> -<div class='nf-center c004'> - <div><span class='pageno' id='Page_110'>110</span>THE AMERICAN</div> - <div class='c000'><span class='xlarge'><span class='sc'>Journal of Microscopy</span>,</span></div> - <div class='c000'>AND</div> - <div class='c000'><span class='large'><i>POPULAR SCIENCE</i>.</span></div> - </div> -</div> - -<hr class='c023' /> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div>PROSPECTUS.</div> - </div> -</div> - -<p class='c019'>The object of the <span class='sc'>Journal of Microscopy</span> is to diffuse a knowledge of the -best methods of using the Microscope; of all valuable improvements in the instrument -and its accessories; of all new methods of microscopical investigation, -and of the most recent results of microscopical research. The <span class='sc'>Journal</span> does -not address itself to those who have long pursued certain special lines of research, -and whose wants can be supplied only by elaborate papers, which, from -their thoroughness, are entitled to be called monographs rather than mere articles. -It is intended rather to meet the wants of those who use the microscope -for purposes of general study, medical work, class instruction, and even amusement, -and who desire, in addition to the information afforded by text-books, -such a knowledge of what others are doing as can be derived only from a periodical. -With this object in view, therefore, the publishers propose to make the -<span class='sc'>Journal</span> so simple, practical and trustworthy, that it will prove to the advantage -of every one who uses the microscope at all to take it.</p> - -<p class='c019'>ILLUSTRATIONS.—The <span class='sc'>Journal</span> will be freely illustrated by engravings -representing either objects of natural history or apparatus connected with the -microscope.</p> - -<p class='c019'>TRANSACTIONS OF SOCIETIES.—<span class='sc'>The American Journal of Microscopy</span> -is not the organ of any Society, but it gives the proceedings of all Societies -whose officers send us a report. As the <span class='sc'>Journal</span> is devoted <i>wholly</i> to Microscopy, -and is in good form and size for binding, no better medium can be had -for preserving the scientific records of any society. Matters of mere business -routine we are frequently obliged to omit for want of room.</p> - -<p class='c019'>EXCHANGES.—An important feature of the <span class='sc'>Journal</span> is the exchange column, -by means of which workers in different parts of the country are enabled, without -expense, except for postage, to exchange slides and materials with each other.</p> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div><b>TERMS.</b></div> - </div> -</div> - -<p class='c019'>During the first two years of its existence, the subscription to the <span class='sc'>American -Journal of Microscopy</span> was only fifty cents per year, but at the request of -more than two-thirds of the subscribers, the size of the <span class='sc'>Journal</span> has been -doubled, and the price raised to</p> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div><b>ONE DOLLAR PER YEAR.</b></div> - </div> -</div> - -<p class='c019'>Four copies for three dollars. Those who wish to economize in the direction -of periodicals, would do well to examine our clubbing list.</p> - -<p class='c019'><span class='sc'>Foreign Subscribers.</span>—The <span class='sc'>Journal</span> will be sent, postage paid, to any -country in the Postal Union for $1.24, or 5 shillings sterling per year. English -postage stamps, American currency or American postage stamps taken in payment. -In return for a postal order or draft for £1 5s., five copies of the <span class='sc'>Journal</span> -will be furnished and mailed to different addresses. Make all drafts and postal -orders payable to John Phin.</p> - -<p class='c019'>BACK VOLUMES.—We have on hand a few copies of Vols. I and II, bound in -handsome cloth cases, which we offer for $1 25 each. Vols. I and II, bound, and -the numbers of Vol. III, as issued, we offer for $2.50. We can no longer supply -complete sets of 1876-7 in sheets. To those who wish to examine the journal, we -will send ten odd numbers for 25 cents.</p> - -<div class='nf-center-c1'> - <div class='nf-center'> - <div><b>Advertisements.</b></div> - </div> -</div> - -<p class='c019'>The <span class='sc'>Journal of Microscopy</span>, from its very nature, is a visitor to the very -best families, and its value as an advertising medium has therefore proved to be -much above that of average periodicals. A few select advertisements will be -inserted at the rate of 30 cents per line, nonpariel measure, of which twelve -lines make an inch. Address</p> - -<div class='c025'><span class='large'>AMERICAN JOURNAL OF MICROSCOPY,</span></div> -<div class='c025'>P. O. Box 4875, New York.</div> -<div class='pbb'> - <hr class='pb c004' /> -</div> - <ul class='ul_1 c004'> - <li>Transcriber’s Notes: - <ul class='ul_2'> - <li>Missing or obscured punctuation was corrected. - </li> - <li>Typographical errors were silently corrected. - </li> - <li>Inconsistent spelling was made consistent when a predominant form was found in this - book; otherwise it was not changed. - </li> - <li>Forms of the name Schäfer were regularized to match the title page of his “A Course - of Practical Histology.” - </li> - </ul> - </li> - </ul> - - - - - - - - -<pre> - - - - - -End of the Project Gutenberg EBook of Section-Cutting: A Practical Guide, by -Sylvester Marsh - -*** END OF THIS PROJECT GUTENBERG EBOOK SECTION-CUTTING: A PRACTICAL GUIDE *** - -***** This file should be named 55930-h.htm or 55930-h.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/5/9/3/55930/ - -Produced by Chris Curnow, Barry Abrahamsen, and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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