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+Project Gutenberg (https://www.gutenberg.org) public repository for
+eBook #68981 (https://www.gutenberg.org/ebooks/68981)
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-The Project Gutenberg eBook of Through a pocket lens, by Henry
-Scherren
-
-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
-will have to check the laws of the country where you are located before
-using this eBook.
-
-Title: Through a pocket lens
-
-Author: Henry Scherren
-
-Release Date: September 13, 2022 [eBook #68981]
-
-Language: English
-
-Produced by: deaurider, Karin Spence and the Online Distributed
-             Proofreading Team at https://www.pgdp.net (This file was
-             produced from images generously made available by The
-             Internet Archive)
-
-*** START OF THE PROJECT GUTENBERG EBOOK THROUGH A POCKET LENS ***
-
-
-
-
-
-  [Illustration:
-
-  PTYCHOPTERA PALUDOSA LIMNOBIA REPLICATA
-
-  _From enlarged photographs, made at the Yorkshire College,
-  Leeds, from specimens bred by the Author, and mounted by Messrs.
-  Watson & Son, High Holborn, London_]
-
-
-
-
-                                THROUGH
-                             A POCKET LENS
-
-                                  BY
-
-                        HENRY SCHERREN, F.Z.S.
-
-                               AUTHOR OF
-     ‘PONDS AND ROCK POOLS,’ ‘A POPULAR HISTORY OF ANIMALS,’ ETC.
-
-
-                      _WITH NINETY ILLUSTRATIONS_
-
-
-                      THE RELIGIOUS TRACT SOCIETY
-
-            56 PATERNOSTER ROW AND 65 ST. PAUL’S CHURCHYARD
-
-                                 1897
-
-
-
-
-                                Oxford
-                HORACE HART, PRINTER TO THE UNIVERSITY
-
-
-
-
-                               CONTENTS
-
-
-                              CHAPTER I.
-
-                                                                PAGE
-
-    THE POCKET LENS, THE DISSECTING MICROSCOPE, AND SOME
-      SIMPLE APPLIANCES                                           11
-
-
-                              CHAPTER II.
-
-    ARTHROPODS AND THEIR CLASSES.--THE MARGINED WATER
-      BEETLE; THE GREAT WATER BEETLE; THE COCKTAIL
-      BEETLE                                                      27
-
-
-                             CHAPTER III.
-
-    COCKROACHES; EARWIGS; THE GREAT GREEN GRASSHOPPER;
-    THE WATER SCORPION; THE WATER BOATMAN; CORIXA                 63
-
-
-                              CHAPTER IV.
-
-    SPIDERS, MITES, AND MYRIAPODS                                 96
-
-
-                              CHAPTER V.
-
-    CRUSTACEANS.--PRAWN, SHRIMP, MYSIS, CRABS; AMPHIPODS;
-    ISOPODS                                                      128
-
-
-                              CHAPTER VI.
-
-    AQUATIC INSECT LARVAE                                        157
-
-    INDEX                                                        189
-
-
-
-
-                         LIST OF ILLUSTRATIONS
-
-
-    FIG.                                                        PAGE
-
-       _Ptychoptera paludosa. Limnobia replicata_     _Frontispiece_
-
-    1. Hand Magnifier and Stand                                   14
-
-    2. Zeiss’s Dissecting Microscope                              16
-
-    3. Leitz’s Dissecting Microscope                              17
-
-    4. Two Leitz Lenses in holder (open)                          18
-
-    5. Two Leitz Lenses in holder (closed)                        18
-
-    6. Home-made Dissecting Microscope                            19
-
-    7. Beakers                                                    21
-
-    8. Glass Capsule                                              21
-
-    9. Glass Block, with cover                                    22
-
-    10. Glass Box, with cover                                     22
-
-    11. Forceps                                                   23
-
-    12. Three forms of Dipping-tube. Method of using it           24
-
-    13. Mounted Needles                                           25
-
-    14. Cape Peripatus (natural size)                             30
-
-    15. Margined Water Beetle (male)                              32
-
-    16. Shells of Molluscs broken up by Dytiscus                  33
-
-    17. Outline of Dytiscus                                       38
-
-    18. Male Dytiscus in flight                                   39
-
-    19. To show fold of (right) wing of Dytiscus                  40
-
-    20. To show fold of (right) wing of Dytiscus                  40
-
-    21 and 21 A. Head of Dytiscus                                 42
-
-    22. Disposition of mouth parts                                43
-
-    23. Leg of Cockroach                                          44
-
-    24. Tarsus of Dytiscus (magnified)                            45
-
-    25. Female Dytiscus swimming                                  46
-
-    26. Upper surface of abdomen of typical Beetle                47
-
-    27. Spiracle of Dytiscus (magnified)                          48
-
-    28. Tracheal tubes of Dytiscus (magnified)                    48
-
-    29. Great Water Beetle                                        51
-
-    30. Female Hydrophilus constructing a cocoon. (After
-          Lyonnet)                                                55
-
-    31. Cocktail Beetle                                           58
-
-    32. Cockroaches                                               66
-
-    33. Mouth parts of a Cockroach                                69
-
-    34. Cockroach, showing Spiracles                              71
-
-    35. Alimentary Canal of Cockroach                             73
-
-    36. American Cockroach (male)                                 75
-
-    37. Larva and Pupa of Earwig                                  77
-
-    38. Earwig (male)                                             78
-
-    39. Great Green Grasshopper (female)                          81
-
-    40. Tibial ear of Great Green Grasshopper                     85
-
-    41. Land Bug (magnified)                                      86
-
-    42. Water Scorpion                                            87
-
-    43. Organs of Water Scorpion, Egg, and Parasitic Mite.
-        (After Swammerdam)                                        90
-
-    44. Raptorial leg of Water Scorpion                           92
-
-    45. Water Boatman                                             93
-
-    46. Water Boatman swimming                                    94
-
-    47. Corixa, with wings expanded                               95
-
-    48. Scheme of under surface of Wolf Spider (female).
-          Pedipalp of male (enlarged)                             98
-
-    49. Garden Spider and Web                                     99
-
-    50. Threads of Spider’s Web                                  100
-
-    51. Anchorage of Web                                         101
-
-    52. Foot of Garden Spider                                    104
-
-    53. Spinnerets of Garden Spider                              104
-
-    54. Jumping Spider                                           106
-
-    55. Falces of Male Jumping Spider                            106
-
-    56. Foot of Jumping Spider. Scopula much enlarged            108
-
-    57. Diving Spiders                                           109
-
-    58. Cell of Diving Spider                                    112
-
-    59. Red Water Mite                                           114
-
-    60. Larva of Water Mite                                      117
-
-    61. Nymph of Water Mite                                      117
-
-    62. Beetle Mite                                              119
-
-    63. _Lithobius forficatus._ Mouth parts seen from below.
-          (After Graber)                                         124
-
-    64. The Common Millepede                                     126
-
-    65. Segments of Millepede (magnified)                        127
-
-    66. Prawn                                                    132
-
-    67. First walking leg of Shrimp (enlarged)                   134
-
-    68. Mysis, or the Opossum Shrimp                             135
-
-    69. Maxillipedes and Maxilla of Shore Crab. (After
-          Savigny)                                               138
-
-    70. Stomach of Crab laid open                                139
-
-    71. Gammarus. (After Sars)                                   142
-
-    72. Maxillipedes of _Gammarus marinus_ (magnified)           146
-
-    73. Nest-building Amphipod (from life)                       148
-
-    74. Water Woodlouse                                          153
-
-    75. Mouth-lock. (After Burgess)                              161
-
-    76. Dytiscus Larvae                                          162
-
-    77. Pupa of Dytiscus                                         164
-
-    78. Larva of _Limnobia replicata_                            167
-
-    79. Forked spine of Limnobia (enlarged)                      168
-
-    80. Pupa case of Limnobia                                    169
-
-    81. Fore wing of Bee, showing marginal fold (×7)             170
-
-    82. Larva of _Paraponyx stratiotata_ (enlarged)              173
-
-    83. Diagram of segment of Paraponyx, showing arrangement
-          of tracheal gills                                      175
-
-    84. Gill of Paraponyx larva. (After De Geer)                 176
-
-    85. Larva of Sialis (enlarged)                               179
-
-    86. Diagram of Sialis larva, showing arrangement of gills    181
-
-    87. Pupa of Sialis                                           181
-
-    88. Larvae of _Ptychoptera paludosa_ (from life)             184
-
-    89. Ptychoptera Larva (enlarged). Tail. (After Lyonnet)      186
-
-    90. Pupa of Ptychoptera. (After Lyonnet)                     187
-
-
-
-
-                         THROUGH A POCKET LENS
-
-
-
-
-                               CHAPTER I
-
-              THE POCKET LENS, THE DISSECTING MICROSCOPE,
-                      AND SOME SIMPLE APPLIANCES
-
-
-The object of this little book is to show how much may be seen
-with an ordinary pocket lens, and with a simple microscope; and,
-as far as possible, to dispel the idea, far too common, especially
-among beginners, that no real work can be done unless one has a
-compound microscope, with a large battery of lenses and an array of
-‘accessories.’
-
-It would be easy to multiply quotations, from high authorities, in
-support of the proposition implied in the foregoing paragraph. Two only
-must suffice.
-
-In a recent review of a very good book dealing with Butterflies and
-Moths (_Natural Science_, vol. vi. p. 293), the following passage
-occurs: ‘The only suggestion we should like to make is that a compound
-microscope is unnecessary for any of the details that the author
-mentions. A first-rate platyscopic hand lens is much more convenient
-and the young naturalist should train himself thoroughly in the use
-of it. There is no more common error than the undue use of the higher
-powers of a microscope. Except for the intimate details of histology, a
-low power or a hand lens is much more easy to use, and its employment
-gives a much better idea of the structure.’
-
-The next quotation is of greater interest, as it gives some insight
-into the way in which Darwin carried on his investigations. In the
-_Life and Letters of Charles Darwin_ (vol. i. pp. 145, 146) we
-are told: ‘His natural tendency was to use simple methods and few
-instruments. The use of the compound microscope has much increased
-since his youth, and this at the expense of the simple one. It strikes
-us nowadays as extraordinary that he should have had no compound
-microscope when he went his Beagle voyage; but in this he followed
-the advice of Robert Brown, who was an authority in such matters. He
-always had a great liking for the simple microscope, and maintained
-that nowadays it was too much neglected, and that one ought always to
-see as much as possible with the simple before taking to the compound
-microscope. In one of his letters he speaks on this point, and remarks
-that he always suspects the work of a man who never uses the simple
-microscope.’
-
-It may be well here to verify the quotations, and also to consult
-Darwin’s _Naturalist’s Voyage_, to ascertain what kind of objects
-he examined with the simple appliances at his command. In the first
-chapter there is an interesting account of a curious limy deposit
-on the rocks of the island of St. Paul’s, and of the discoloration
-by confervae of the water, which, ‘under a weak lens, seemed as if
-covered by chopped bits of hay, with their ends jagged.’ Then we have
-an account of the confervae in the Indian Ocean, and of infusoria so
-numerous as to tinge the water off the coast of Chile. In the second
-chapter we have observations and experiments on planarian worms.
-‘Having cut one of them transversely into two nearly equal parts, in
-the course of a fortnight both had the shape of perfect animals.’ In
-the next chapter he records some observations on the structure of
-vitrified tubes formed by lightning striking loose sand. In the fifth
-chapter is an elaborate description of a kind of sea-pen; and in the
-ninth chapter there are some remarks on the vast number of eggs in the
-egg-ribbon of a sea-slug, and on the ‘bird’s-head’ organs in certain
-Polyzoa. These remarks were, of course, founded on actual inspection
-with the simple microscope.
-
-To this instrument, also, we owe the discovery of the tadpole-like
-larvae of Ascidians, or Tunicates, as they are now generally called.
-‘At the Falkland Islands I had the satisfaction of seeing, in April,
-1833, and therefore some years before any other naturalist, the
-locomotive larvae of a compound ascidian.... The tail was about five
-times as long as the oblong head, and terminated in a very fine
-filament. It was, as sketched by me under a simple microscope, plainly
-divided by transverse opaque partitions, which I presume represent the
-great cells figured by Kovalevsky. At an early stage of development the
-tail was closely coiled round the head of the larva[1].’
-
-       *       *       *       *       *
-
-We come now to our pocket lens, which may be purchased for a few
-shillings of any optician. One can buy a serviceable single lens,
-in an ebonite handle, for a shilling; and this cheap instrument is
-sufficiently powerful not only to give the worker a good general idea
-of the form and structure of objects, but to enable him to do real
-work. With it the habits of many of the inmates of his aquaria may
-conveniently be watched; he may see their development from stage to
-stage of their life-history; and with it, when they are broken up, he
-may make out a good deal of their external and internal anatomy.
-
-  [Illustration: FIG. 1.--Hand Magnifier and Stand.]
-
-A very good form is shown at Fig. 1, which represents a hand magnifier,
-fitted with three lenses of different focus, generally 2 in., 1½
-in., and 1 in. Examination of the catalogues of the principal London
-opticians shows that such a set of lenses may be bought for about
-3_s._ In shape and construction there is sometimes a little
-variation; but the form figured is that most generally adopted, and is,
-on the whole, fairly convenient. It would, however, be an advantage if
-the hole by which the magnifier is mounted on the stand were drilled
-in the solid part of the handle. This would not only do away with the
-objection that the hole in the case permits dust to penetrate to the
-glasses, when carried in the pocket, but would give a longer reach, and
-thus obviate the necessity for moving the stand if the observer were
-examining a large object. The price of the stand figured is 2_s._
-6_d._; and one with a short adjusting arm ought not to cost much
-more.
-
-Any one with a mechanical turn may make a stand for himself, though it
-may be doubted whether this is quite worth while when these articles
-may be bought so cheaply. Nevertheless, there is great pleasure in
-making things for oneself; and a home-made stand will enable the
-observer to do quite as good work as one that came from the optician’s
-shop.
-
-A bill-file weighted at the foot may be bought for a few pence, and
-adapted to the purpose. For the slider a large cork cleanly pierced
-will answer admirably. This should carry a piece of stout wire, bent
-at the end thus __|[image], to serve as a holder for the magnifier,
-which should have a hole in the handle, for the reasons stated above.
-The only difficulty will be the attachment of the wire to the cork. The
-Rev. J. G. Wood advocated winding the wire round the cork in a spiral;
-and this is a very good plan. An increase of steadiness is secured, if
-a larger cork, or small bung, be used, and the wire inserted in the
-side.
-
-There are, of course, more expensive lenses, with which better
-definition can be obtained. Zeiss has an excellent magnifier consisting
-of two lenses, for use in the dissecting microscope (Fig. 2), and
-also as a hand lens, at the price of 6_s._; one of the same
-construction, for use in the dissecting microscope alone, may be had
-for 4_s._ The Steinheil achromatic lenses are probably the best
-of all. These are made in powers ranging from 2 in. to ½ in. focus[2];
-and the price varies from 10_s._ up to £1, according to the maker.
-Those made by Leitz of Wetzlar cannot be surpassed; and they are sold
-in London at 10_s._ each, either mounted in a handle, for use
-as hand magnifiers, or with a collar for use in Leitz’s dissecting
-microscope (Fig. 3). Mr. Lewis Wright says that ‘the best plan is to
-combine both uses, and have two or three powers in collars, with a
-spring ring folding into a handle, which will carry any one of them in
-that manner. A Steinheil lens at this low price costs little more than
-a Coddington, while its performance is infinitely superior[3].’ It is
-a difficult thing to get makers to deviate from the beaten track, and
-so far as I have been able to learn, Mr. Wright’s wishes have not been
-fulfilled.
-
-  [Illustration: FIG. 2.--Zeiss’s Dissecting Microscope.]
-
-The lenses and stand (Fig. 1) constitute a simple form of dissecting
-microscope. If the worker wishes for something more elaborate, he need
-only consult the catalogues of the principal makers to find something
-that will meet his requirements. Zeiss’s brass stand, with stage, above
-which a lens slides up and down in a holder (Fig. 2), is sold for
-9_s._; with blocks for supporting the hands, at 10_s._ It is
-a useful instrument for small objects.
-
-My favourite instrument is shown at Fig. 3. Here the focussing of the
-lens is effected by rack and pinion work, by means of the screws on
-each side the upright pillar. The lens is shown fitted in the collar
-which carries it. The stage is of glass--roughly, 2½ in. long by 2
-in. wide, and the arm at the top of the pillar can be moved from side
-to side, so as to bring a fairly large object within range. The metal
-framework of the stage is furnished with nickelled clips (not shown),
-which serve to hold an excavated slip. The arm-rests are detachable,
-and the uprights are hinged for convenience of packing. The instrument
-(with the exception of these rests) packs into a neat, strong mahogany
-box, 7½ in. in length, and about 5 in. in height and width. With
-two powers--1 in. and ½ in. are very serviceable ones--the cost is
-38_s._
-
-  [Illustration: FIG. 3.--Leitz’s Dissecting Microscope.]
-
-It is to be wished that the maker would devise some plan by which the
-admirable lenses sold with this instrument could be utilized for the
-pocket. Mr. C. Curties, of Baker & Co., High Holborn, has kindly done
-something in the matter, and has made for me a metal holder. I have
-found this convenient, but should be glad to see something further done
-in the same direction, so that instrument, lenses, and holder could be
-sold for £2. This ought to be within the range of practical optics. The
-spring collar advocated by my friend Mr. Wright seems better, and would
-certainly be cheaper. The lenses would only need to be dropped in. To
-use my pocket holder one must unscrew the metal collar from the lenses
-before screwing them into the metal plates which carry them (Fig. 4).
-It is, however, something to have made a beginning: it is a step in the
-right direction.
-
-  [Illustration: FIG. 4.--Two Leitz Lenses in holder
-  (open).]
-
-  [Illustration: FIG. 5.--Two Leitz Lenses in holder
-  (closed).]
-
-A serviceable dissecting microscope--not a toy, but an instrument with
-which real work may be done--can be made at a cost of a few shillings.
-Such a one has been made for me by a friend with a positive genius
-for such work. The body is fashioned out of a parcel-post box 7 in.
-long, 3½ in. in height, and the same in width. From the centre of the
-sliding top a piece is cut away, leaving ledges to take a 3 in. by 1
-in. excavated slip for small dissections, or a mounted slide of a large
-object, such as a whole insect, for examination. A further portion is
-cut away on each side to take a small dissecting dish (Fig. 6). To
-admit the light, a hole is cut in the side of the box; and the mirror
-consists of a piece of silvered glass which was bought of a hawker in
-the street. This is placed in the box opposite the square hole, and
-sloped at an angle of 45°. The aid of a skilled mechanic was sought
-for a small rod carrying a thread, which works in a piece of brass
-bent at a right angle. This piece of brass is screwed on the box, just
-above the aperture by which light is admitted, and carries a pocket
-magnifier, similar to that shown at Fig. 1.
-
-  [Illustration: FIG. 6.--Home-made Dissecting Microscope.]
-
-This modest little instrument generally stands on my work-table, and
-has provoked some remark and a little good-natured banter from friends
-who have seen it. Nevertheless, I should be sorry to part with it, for
-I have found it extremely serviceable in many ways. And more than one
-critic has had to confess that better results were obtained than one
-would expect from its appearance. The total cost out of pocket was,
-3_d._ for the box, 3_s._ for the lens, and 1_d._ for the plate-glass,
-while the man who made the pillar and ear-piece would take no more
-than 6_d._ for his work. This brings the total to 3_s._ 10_d._ With a
-little ingenuity the pillar might be made to carry a collar, and so
-take a Steinheil lens. This would swell the total cost to about 11_s._
-
-Other apparatus need not be costly. An incident occurred at the meeting
-of the Quekett Microscopical Club on November 22, 1878, which shows
-how readily common objects may be utilized for our purpose. The late
-Right Hon. T. H. Huxley, who was at that time President, exhibited,
-and made some remarks on, the dissecting microscope which now bears
-his name. During the discussion which followed, Professor Charles
-Stewart exhibited some little saucers, which were admirably adapted
-for dissecting purposes. The President said that he should ‘be glad
-to know where these convenient little saucers could be obtained.’ The
-next paragraph of the minutes is interesting and instructive. ‘Mr.
-Stewart said they were to be found at the corners of the streets,
-containing three whelks or three mussels for a penny. He bought those
-he had brought to the meeting at a shop in the New Cut, where they were
-supplied to costermongers[4].’
-
-As very many of the objects with which we are concerned are aquatic,
-we shall want vessels of some sort to serve as aquaria. Any glass
-vessel will answer our purpose, provided it is clear, to allow of the
-examination of our captives; or shallow pie-dishes may be utilized.
-The glass pots in which preserves are sold will do admirably, and any
-glazier will cut us covers for a few pence. Within reasonable limits,
-the smaller the aquaria are the better. The inmates can be seen more
-easily, and picked out with less trouble when one wishes to examine
-them.
-
-The principles on which aquaria should be kept are now pretty generally
-understood. There should always be a small quantity of growing aquatic
-vegetation, and a supply of minute life to furnish food for the larger
-forms. Excess of light should be avoided, and the temperature should
-not be allowed to rise much above 50° F. Carnivorous beetles and their
-larvae may be fed with small pieces of meat, small garden worms, or
-tadpoles. Most of the smaller larvae treated of will be satisfied with
-vegetarian diet, varied with an occasional meal of water-fleas.
-
-  [Illustration: FIG. 7.--Beakers.]
-
-  [Illustration: FIG. 8.--Glass Capsule.]
-
-If one cannot lay the household stores under contribution for jam-pots,
-tumblers, and bottles, beakers (Fig. 7) make capital small aquaria.
-They are sold in nests, and may be had either rimmed or lipped--rimmed
-for choice. There is no difficulty in obtaining them of any optician or
-glass-merchant. Mine have been bought from Messrs. Beck, of Cornhill,
-as have the capsules, &c., figured here.
-
-Glass capsules (Fig. 8) are made in different sizes, ranging from 1½
-in. to 3 in. in diameter, with a height of 1 in. or 2 in. The largest
-size, 3 in. by 2 in., costs 5_d._, and a glass circle to cover it,
-1_d._ These capsules will be found useful for small aquaria, and
-for isolating aquatic larvae in order to keep them under observation
-during their change to perfect insects. It was in a capsule of this
-kind that some of my Ptychoptera larvae (p. 184) were kept, and changed
-into the pupal condition.
-
-The glass block, with cover (Fig. 9), is convenient for a number of
-purposes. In it small creatures may be examined in air or in water, and
-it makes an exceedingly convenient little dissecting dish for use with
-the mounted hand magnifier (Fig. 1), or with Leitz’s stand (Fig. 3), or
-the home-made stand (Fig. 6). The glass box, with cover (Fig. 10), is
-extremely good for keeping small creatures under observation.
-
-  [Illustration: FIG. 9.--Glass Block, with cover.]
-
-  [Illustration: FIG. 10.--Glass Box, with cover.]
-
-Excavated glass slips, 3 in. by 1 in., may be bought from any optician.
-They serve for the examination of objects in water, and also for
-dissection. The best I have been able to get have been supplied by Mr.
-J. Hornell, of the Biological Laboratory, Jersey, and they are very
-cheap.
-
-We shall need some forceps to pick up specimens from the vessels
-in which they are kept, and the same little instruments will be
-found convenient in collecting. Both forms have advantages of their
-own; if we are limited to one pair, they should be curved, and of
-brass. Forceps with ivory tips are very useful for handling aquatic
-vegetation. These articles are not usually sold by opticians, but
-are kept by the tradesmen in Clerkenwell who sell jewellers’ and
-watchmakers’ tools, and cost from 1_s._ to 1_s._ 6_d._ a
-pair.
-
-  [Illustration: FIG. 11.--Forceps.]
-
-Dipping-tubes are used to take up small aquatic animals from the
-vessels in which they are kept. Very little practice will render the
-use of this instrument easy. The tube is held firmly between the thumb
-and the third and fourth fingers of either hand, while the index finger
-is pressed firmly on the top. Most people naturally prefer the right
-hand, but it is well to accustom oneself to use the right or left
-indifferently. The open end is then put into the water, just over the
-object to be secured, and the index finger lifted. The rush of water
-into the tube will carry the object into it, and if the finger be again
-applied to the top, the pressure of the atmosphere will prevent the
-water from escaping when the tube is lifted out[5].
-
-Small brushes are useful for taking up specimens from the water or from
-pickle; common ones will do very well for large objects, but for small
-objects and parts it is advisable to have one or two sable brushes, as
-these form a better point.
-
-Some needles fixed in handles will also be necessary. These may be
-bought, or made by fixing ordinary needles of requisite sizes into the
-handles sold for small brushes. The needles must be kept free from
-rust, and should always be carefully wiped after use. A good plan to
-keep them clean is to stick them in a gallipot in which has been
-melted a mixture of lard and paraffin in equal proportions.
-
-Small dissecting-knives are useful, but all the work described here may
-be done with an ordinary pocket-knife in good trim.
-
-  [Illustration: FIG. 12.--Three forms of Dipping-tube.
-  Method of using it.]
-
-The best preservative for our purpose is formalin, which is sold in
-a forty per cent. solution. This should be treated as absolute, and
-a five per cent. solution made. This will really be a two per cent.
-solution, and is sufficiently strong for general use.
-
-The most profitable use we can make of specimens is to watch their
-habits while living, and to break them up and learn as much as we can
-about their structure when they are dead. For us to make a collection
-of specimens in tubes would be a waste of material.
-
-  [Illustration: FIG. 13.--Mounted Needles.]
-
-Little need be said about collecting. The objects treated of are
-so plentiful that no great skill, nor any wealth of appliances, is
-needed to secure an ample supply. The following remarks on the methods
-employed at the Illinois State Laboratory for the capture of aquatic
-insects and larvae are, however, worth quoting:--
-
-‘Insects in vegetation, and on or in the bottom, were taken by means of
-a dip-net--a net of about equal depth and width attached to a strong
-semicircular ring, firmly fixed to a long handle, the straight side of
-the ring being opposite the point of attachment. For the larger and
-more active forms, a coarser net was used, and for smaller forms one
-made of finer net proved most durable and satisfactory. To collect from
-the mud of the bottom, the water immediately over it was violently
-stirred and then swept with the net. The surface layer of mud was also
-scooped up in the fine dip-net, and then allowed to wash through,
-leaving the coarser contents in the net. Insects on the bottom in deep
-water were secured by using a dredge, and washing its contents through
-net sieves. The aquatic vegetation, when free from mud, was violently
-washed in a large pan, many smaller forms being thus dislodged and
-coming to the surface. Insects occurring in open water were taken in
-drawing an ordinary towing-net[6].’
-
-Here we have, so to speak, the general principles of collecting. It
-will be easy to adapt them to particular cases.
-
-In choosing the subjects to be treated of in this little book, some
-difficulty has been experienced in deciding what to select from the
-multitude that lay ready to hand. It was felt necessary that the
-subjects should be connected, since choosing them at random would
-lead to purposeless work, and so to waste of time and opportunity.
-After some consideration, the author has decided to take all the
-examples from the Arthrop´oda--that great sub-kingdom of backboneless
-animals which includes the Lobster, the Crab, the Sand-hopper and the
-Woodlouse, the Spider and the Mite, the whole world of Insects and the
-Centipedes. One cogent reason that influenced this decision was the
-fact that these objects are exceedingly common, so that there can be no
-difficulty in procuring material on which to work. There is, perhaps,
-no other sub-kingdom so full of interest, on account of the many widely
-different forms, which may be referred to one common plan.
-
-It may possibly appear to some readers that the powers of the pocket
-lens have been exaggerated. As a matter of fact the material for the
-book has been gathered by actual observation. The author has seen, with
-an ordinary pocket lens, the objects here described. If some are shown
-as they would appear under greater magnification than such a lens would
-give, this is chiefly for the sake of emphasizing points of interest
-which might otherwise be overlooked, but which can readily be made out
-with a hand magnifier, when attention has been drawn to them, and the
-observer knows what to look for.
-
-
-
-
-                              CHAPTER II
-
-              ARTHROPODS AND THEIR CLASSES.--THE MARGINED
-                 WATER BEETLE; THE GREAT WATER BEETLE;
-                          THE COCKTAIL BEETLE
-
-
-Having got together our apparatus, which, as we have seen, need be
-neither costly nor complicated, the next step will be to acquire some
-knowledge of the group from which the examples here treated of will be
-taken--the Ar´thropods, or animals with hollow-jointed limbs. These
-are the ‘Insects’ of the Linnaean classification, and, for the matter
-of that, of popular phraseology; for though few people would now
-venture to call a Lobster an ‘insect,’ we still style some of its near
-relatives Water ‘Fleas,’ as Swammerdam did two hundred years ago.
-
-The Arthropods form a phylum, or main division of the Animal Kingdom.
-Above this phylum comes that of the Molluscs, or soft-bodied animals,
-such as the Oyster, the Snail, and the Cuttlefish. Still higher are the
-Lancelet, the Sea-squirts, and some few others, that bridge the chasm
-between the phyla without, and that phylum with, a backbone. And to
-this last Man himself belongs.
-
-Two reasons contributed to the selection of the Arthropods as a subject
-for work with the pocket lens: (1) the great interest which surrounds
-many of the group; and (2) the ease with which specimens may be
-procured and kept under observation.
-
-Every one has pretty clear notions as to the general ‘make’ of a
-Vertebrate or backboned animal. An Invertebrate animal has, of course,
-no backbone or the semblance of one; the nervecord, where present, lies
-on the under surface, and forms a ring round the gullet, and the heart
-lies on the upper surface or back. We may verify this by pulling to
-pieces a dead insect.
-
-But a phylum, or main division, is much too large to be considered as a
-whole. It must, therefore, be broken up into smaller groups, which are
-called Classes, generally reckoned as five in number. These, again, may
-be grouped into two divisions, according as their members breathe by
-means of air-tubes (_tracheae_) or by gills. Our scheme then will
-stand thus:--
-
-               {                { Peripatus.
-               { Breathing by   { Centipedes and Millipedes.
-               {   air-tubes    { Insects.
-    ARTHROPODS {                { Spiders and their kin.
-               {
-               { Breathing by   { Lobsters, Crabs, Sand-hoppers,
-               {   gills        {   and Woodlice.
-
-This scheme looks well on paper; and on the whole is workable. But
-among our examples chosen from the Class of Insects, we shall find some
-that breathe by gills in their larval stage, and by air-tubes when
-adult. And among the Crabs are some, the gills of which have ceased
-to perform their normal function, so that these animals cannot live
-in water for a single day. And then there are the Sand-hoppers and
-Woodlice.
-
-The body of an Arthropod may be represented by a series of similar
-rings, thus:
-
-  [Illustration]
-
-This similarity is clearly apparent in the Centipede, but is concealed
-in the Beetle, the Shrimp, and the Spider. It seems, at first sight,
-to be altogether lost in the Crab, and does really vanish in the adult
-stage of some parasitic Crustaceans.
-
-It may be plausibly objected that our ideal Arthropod resembles nothing
-so much as a worm. In many respects this is true. A primitive Arthropod
-was worm-like, as is a Centipede. And Arthropods and Worms were
-formerly classed together in one group, as Annulo´sa or ringed animals.
-The chief external difference lies in the nature of the appendages
-borne by the various rings or segments.
-
-We may represent those of the Worms thus [image], for they are
-bristles, or groups, or modifications of bristles. Those of the
-Arthropods may be represented thus [image], for the appendages are
-really jointed, though, of course, in a fashion different from those of
-a backboned animal.
-
-The jointed appendages of Arthropods may be modified to fulfil very
-different functions. They may serve as legs for walking, hands for
-climbing or seizing prey, jaws for masticating food, feelers or organs
-of touch and sense, and, strange as it may seem, in one group, as eyes.
-
-It is well to get some notion of how these joints are formed. To take
-the body first: the skin connecting the segments is much thinner than
-that of the segments themselves, which is thickened by the deposition
-of chitine, and, in some cases, also of carbonate and phosphate of
-lime. A portion of the body, then, may be represented thus, [image]
-where the heavy lines denote the segments, and the thin ones the spaces
-between the segments. It will be seen that this arrangement allows
-of considerable play, and also of a telescopic movement by which the
-segments can be brought close together.
-
-It is easy to construct a kind of model that shall exemplify these
-movements. Make a tube of calico, some six inches long, and having
-stuffed it with cotton-wool, paste on it strips of brown paper one inch
-in width, leaving an interval between each, as in the last diagram.
-Then we shall be able to understand how Arthropods can bend the body or
-move it from side to side. And the limb joints are made on a similar
-plan.
-
-  [Illustration: FIG. 14.--Cape Peripatus (natural size).]
-
-The most archaic Arthropod--Perip´atus--must be mentioned. It is not
-found in Britain, nor even in Europe; so that, unless we travel, we
-shall only know it from books, or from museum specimens. But it is an
-extremely interesting creature, for it is of worm-like aspect, and
-breathes by air-tubes, opening all over the body, which has no external
-segments. The limbs are imperfectly jointed, and each of them bears
-two claws. Most naturalists make this genus a Class by itself, while
-some put it with the Centipedes. There are about a dozen species, four
-of which are African, two Australian, and the rest are found in South
-America and the West Indies. Besides these there are some doubtful
-species.
-
-In habit they resemble the Centipedes, and they ensnare the insects on
-which they feed by ejecting sticky slime from the small processes near
-the mouth. The left process is shown in the illustration, just below
-the antenna of that side.
-
-Professor Sedgwick, who described these animals in the _Quarterly
-Journal of Microscopical Science_ (1888), and, more popularly,
-in the _Cambridge Natural History_, says, that ‘the exquisite
-sensitiveness and changing form of the antennae, the well-rounded plump
-body, the eyes set like small diamonds on the side of the head, the
-delicate feet, and, above all, the rich colouring and velvety texture
-of the skin, all combine to give these animals an aspect of quite
-exceptional beauty.’
-
-Unfortunately, an illustration in black-and-white can only render
-form. We must take the beauty of the colouring for granted. One thing,
-however, cannot escape the most cursory examination of the picture--the
-resemblance of the creature, in some respects, to a worm, and, in
-others, to a caterpillar, which, as everybody knows, is the larval
-stage of a butterfly. If this resemblance sets us thinking how it came
-about, and what it means, Peripatus will, for the present, have done
-its work for us.
-
-       *       *       *       *       *
-
-With these general notions of Arthropods, we may pass on to put our
-pocket lens to some practical use. Our first subject shall be the
-Margined Water Beetle (_Dytis´cus margina´lis_), which can be
-taken in almost any open pond in the country. Water covered with
-duckweed should be avoided in hunting for these beetles, which prefer
-ponds with a clear surface, so that they may easily come to the top to
-breathe.
-
-Every one has a good general notion of the principal Insect-groups,
-technically called Orders--Beetles, Cockroaches and Grasshoppers,
-Butterflies, Bees and Wasps, and Flies. Insects may be defined
-as animals with hollow-jointed limbs, and divided into three
-regions--head, thorax, and abdomen. The head bears a pair of antennae;
-the thorax carries three pairs of legs, and (generally) two pairs of
-wings; the abdomen is without appendages. Insects when adult breathe
-by tubes that open to admit air. In Chapter VI we shall see that many
-larvae obtain an air supply in different ways.
-
-  [Illustration: FIG. 15.--Margined Water Beetle (male).]
-
-Beetles may be taken as very good types of true Insects. They
-constitute the Order Coleop´tera, or Insects with sheathed wings, only
-the hinder pair being used for flight (Fig. 18), and at other times
-they are folded under the wing-cases, or el´ytra, as in Fig. 15.
-
-We may advantageously compare our Beetle with Peripatus, and note the
-points of agreement and of difference.
-
-Now, if our captive Beetles are to yield us the greatest possible
-amount of profit, we shall keep them under observation for some time,
-so as to watch their habits.
-
-In keeping these Beetles we shall not require a large aquarium. A small
-gathering of aquatic weed will be necessary to keep the water in good
-condition and the aquarium ready for its tenants.
-
-My interest in these Beetles was quickened by a letter in the
-_Field_ (Oct. 28, 1893), in which a correspondent at Weybridge
-asked ‘for information as to what animal or bird bisects so neatly the
-shells of the Water Snail (_Planorbis_).’ I thought then, and
-know now, that the shells were ‘bisected,’ if that is the proper word,
-by Water Beetles. From that time I have had, and still have, several
-living in small aquaria, but for a long time was unable to get direct
-evidence on the subject.
-
-  [Illustration: FIG. 16.--Shells of Molluscs broken up by
-  Dytiscus.
-
-  (From a photograph by Cherry Kearton.)]
-
-Many experiments were tried, and at last these proved successful.
-Several specimens of Dytiscus[7] were obtained, and put into a small
-aquarium in which was no other food for them than some snails and other
-molluscs. The Beetles were carefully watched, and were several times
-seen trying the snails. In crawling along the inner surface of the
-glass, Planorbis and Limnaea both protrude the foot to a considerable
-extent, and pieces were ripped out by the strong mandibles of the
-Beetles before the shells were actually broken up.
-
-All the shells represented in Fig. 16 were taken from this aquarium,
-so that there is good evidence as to what creatures broke them up and
-devoured their inmates. In these, as in the specimen kindly sent me by
-Mr. Tegetmeier, the Natural History Editor of the _Field_, the
-bisection is not complete, though in all cases it is carried far enough
-to allow of the extraction of the mollusc. The large Limnaea shell in
-the centre has been attacked, but it seems to have been left when the
-beetles discovered it was empty. (The empty shell was noted before the
-Beetles were put into the tank.) Another Limnaea shell is figured, from
-which the snail has been picked out, and that of a fresh-water mollusc.
-
-After these observations had been recorded in the _Field_[8], I
-found that I had been anticipated by about forty years. I picked up,
-at a bookstall, a copy of G. B. Sowerby’s _Popular History of the
-Aquarium_, and there I found that the author had distinctly seen
-Dytiscus at this kind of work. He says[9]: ‘I have only once witnessed
-him in the act of seizing an unfortunate Planorbis or Flat-coiled Water
-Snail. At first, the Dytiscus seemed to be roaming about in quest
-of something, first under, then over, the leaves of a water-lily.
-At last, in a rather dark corner, he seemed to perceive suddenly a
-Planorbis which was browsing upon the stem of a plant just under the
-shade of a broad leaf. He darted at this, seized it, and then, putting
-his tail out of water, for the purpose of taking in a fresh supply of
-air, moved slowly down, bearing the snail with him. He held it by his
-fore-feet, turning round the coil until the aperture of the shell was
-opposite his mandibles, then he began nibbling away at the animal. In
-vain did the poor mollusc try to withdraw within its shelly fortress,
-for the beetle picked off the edges of the shell bit by bit, so as to
-expose the body as fast as it was withdrawn. All the way down to the
-bottom of the tank was this process continued, air-bubbles rising to
-the top, and bits of broken shell falling, till the beetle with his
-burden reached a stone near the bottom, where I left him still busy at
-his work.’
-
-This puts the matter beyond doubt, if any before existed. I at once
-wrote to Mr. Tegetmeier to let him know that my experiments had,
-unknown to me, been anticipated, long ago, by Mr. Sowerby. Had
-he rescued his Planorbis shell, it would have compared very well
-with those forwarded to the _Field_ office in 1893. They had
-been exhibited at the Malacological Society, and no one was able
-to solve the mystery of their mutilation. This shows, to quote the
-_Field_[10] on the subject, ‘how easily statements that have been
-recorded may subsequently be overlooked and entirely forgotten.’
-
-To return to our Beetle. The male is a handsome creature, from an inch
-to an inch and a quarter long, clad in olive-green, bordered with
-yellow, and exceedingly active. His mate is smaller, more soberly clad
-in brown, without the yellow markings, and the wing-cases are more or
-less furrowed.
-
-The first thing to notice is the shape of the body, oval and smooth,
-offering no resistance to the water. The hind pair of legs are
-flattened and fringed with hairs, so as to make capital paddles. In
-swimming the right and left legs are moved together.
-
-Now, though this Beetle lives in the water, it is made, so far as
-concerns its breathing apparatus, after the fashion of a Land Beetle,
-and consequently is compelled to come to the surface pretty frequently
-for a supply of air, which it obtains in this wise. Directly it ceases
-paddling it floats to the top of the water; and as the head is heavier
-than the tail the latter projects a little above the surface. Then the
-wing-cases are raised, and air flows in under them to the breathing
-holes on each side. The operation is not a long one, and as soon as it
-is over the Beetle is ready for another ramble round his dwelling-house.
-
-But if we do not supply our captive with food that he may take for
-himself, it is only right that we should feed him, which may be done at
-intervals--say, every other day. ‘Little, and often,’ is an excellent
-motto to guide us in our feeding; and though its adoption may entail
-some trouble, it will be more than compensated by the success that
-will attend our endeavours to keep the inmates of our aquarium in good
-condition. And the operation of feeding our Beetle will show us that he
-has some capital sense-organs, which are of as much, if not of more,
-use to him than his eyes.
-
-He is a flesh-eater. Let us take a small piece of meat or fish in a
-pair of forceps, or stuck on a pointed stick, and hold it at a little
-distance from his great eyes. The chances are that he will not see it.
-Even if we put it in front of him, he is quite likely to disregard it,
-for he has nothing corresponding to a nose, with which he may smell.
-From his head there spring a pair of long feelers--the antennae--and by
-means of these we will let him know that his dinner is ready. That is
-effected by drawing the food along the side of one of the antennae. The
-creature undergoes a sudden change. Till the antenna was touched with
-the food he was resting on his swimming legs. But in a moment down goes
-his tail and up goes his head, he stretches out his raptorial legs, and
-clutches wildly at the forceps or stick, as the case may be, holding so
-tight that he may be dragged round and round the glass vessel. Let go
-he will not, of his own accord; and it would be a difficult matter to
-shake him off. Similar experiments may be tried with other Beetles, and
-the result will be to impress on the mind the fact that the feelers are
-capital sense-organs.
-
-If we are to turn our Beetle to the best account, we shall need to
-handle him. It may be inconvenient to wait till he dies, so we will
-kill him quickly and painlessly by plunging him into boiling water, and
-he may be preserved by putting him into a tube containing about equal
-parts of water and spirit, or a five per cent. solution of formalin.
-
-Dissections should properly be made under water. The Beetle should be
-fastened, back upwards, to a piece of cork weighted with lead, and
-placed in a deep saucer, or dissecting dish, and covered with water.
-But a good deal of rough dissection, as is ours, may be done in air,
-and the Beetle may be fastened to any convenient piece of board, or
-even held in the palm of the left hand. Very little practice is needed
-to run over the external parts of a large Beetle in this manner.
-
-  [Illustration:
-
-   FIG. 17.--Outline of Dytiscus (male). _a_,
-   antenna; _b_, maxillary palp; _c_, eye; _d_,
-   fore-leg; _e_, thorax; _f_, middle leg; _g_,
-   elytron; _h_, suture; _i_, hind leg; _j_, claw;
-   _k_, tarsus or foot; _l_, tibia or shank; _m_,
-   femur or thigh; _n_, first three joints of foot, widened
-   into a plate with suckers beneath.]
-
-First, let us look over our Beetle, and get some general notions of
-its make. As it lies, back upwards, it is clear that it consists of
-three parts or regions------------[image], the first of which is the
-head, the second the thorax, and the third the abdomen. Not only in our
-Beetle, but in Insects generally, these parts correspond to the words
-that denote them, in that the thorax is longer than the head, and the
-abdomen longer than the thorax, as shown by the three dashes, a few
-lines above.
-
-These divisions are well shown in Fig. 17, where other parts are also
-marked. It will pay to go over our own specimen with this figure before
-us, and so make acquaintance with the several parts, to some of which
-we shall return in greater detail.
-
-  [Illustration: FIG. 18.--Male Dytiscus in flight.]
-
-At this point, if we have not done so before, it will be convenient
-to fasten our Beetle, in the position figured, by a stout pin driven
-between the thorax and the abdomen, just above the suture (_h_).
-We want to raise one of the wing-cases.
-
-If a needle be taken in each hand, between the thumb and first two
-fingers, and that in the left hand be used to steady the creature, the
-wing-case on the right may be raised with the needle in the right hand,
-and then cut off. The small filmy membrane, of somewhat triangular
-shape, which comes off with the wing-case, is the winglet. There is
-one on each side; and their vibration causes the humming noise made by
-these insects in flight. When the water dries up in one pond, or food
-becomes scarce, they will leave and fly off to another.
-
-The wing lies folded upon the abdomen. A good deal of very interesting
-matter has been written on the way in which Insects fold their wings,
-but we can see for ourselves how this Beetle folds them. All we have to
-do is to take the wing, and draw it gently away from us, and so unfold
-it. We may use finger and thumb, or a small pair of forceps. When let
-go, it will spring back to its old position. Reference to the expanded
-wing in Fig. 18, and to the diagrams Figs. 19 and 20, will show how the
-wing is folded.
-
-  [Illustration: FIG. 19.--To show fold of (right) wing of
-  Dytiscus.]
-
-  [Illustration: FIG. 20.--To show fold of (right) wing of
-  Dytiscus.]
-
-The cross-mark in the diagram represents a joint in the chitinous rod
-that forms the wings. This lies just above the cell (which is left
-white in Fig. 18). The shorter part of the rod is bent down, forming an
-acute angle (Fig. 20); of course, carrying with it the membranous part
-of the wing.
-
-This may seem a little difficult. But if it be tried on a specimen, no
-real difficulty will be experienced. When the wing has been unfolded,
-it will, if let go, spring back to its old position, the shorter part
-lying underneath, and the chitinous rod fitting into a groove formed by
-the projecting sides of the segments of the abdomen.
-
-To this point the sum of our knowledge about Dytiscus amounts
-to this: It is aquatic in habits; its body is divided into three
-regions; and it has a pair of membranous wings, covered by chitinous
-wing-cases, or sheaths, technically called _el´ytra_ (each being
-an _el´ytron_). Wing-cases of this kind are the distinguishing
-mark of the Beetles, or _Coleop´tera_, though they are not always
-so well developed as in the specimen with which we are dealing. This we
-can discover for ourselves by examining all the Land Beetles met with
-in a country ramble or in a stroll round the garden.
-
-Now let us unpin our Beetle, turn it on its back, and examine it from
-the under side. Head, thorax, and abdomen may be made out more clearly
-than before, and we can see that the last two regions are divided into
-segments.
-
-Let us deal with the head first. This may be easily separated from the
-thorax with a dissecting needle, or with a pocket-knife--an exceedingly
-handy tool. The huge goggle-eyes cannot escape observation; and, even
-without a magnifier, they may be seen to be compound--that is, made up
-of a number of facets, which show like a fine network.
-
-Just in front of the eyes are the antennae, which serve as organs of
-touch and perhaps also of other senses.
-
-Kirby has recorded facts which seem to show that the antennae (in
-some cases) are also organs of hearing. Other authorities, after many
-observations, have come to the same conclusion. The matter, however,
-is beset with difficulty. It is certain that some Insects have their
-ears in their legs; and for the present, at any rate, we may be
-satisfied to know that the antennae are sense-organs, certainly of
-touch, probably of smell, and, in some cases, of hearing. An excellent
-authority on the subject is Sir John Lubbock’s book, _The Senses of
-Animals_[11], which contains references to very many original papers.
-
-  [Illustration: FIG. 21.
-
-   FIG. 21.--Upper surface of head of Dytiscus. _a_,
-   labrum, or upper lip; _b_, clypeus or shield; _c_,
-   mandible dissected out, and (_d_) reversed; _e_, eye;
-   _f_, antennae.]
-
-  [Illustration: FIG. 21 A.
-
-   FIG. 21 A.--Under surface. _a_, mentum or chin; _b_, ligula
-   or tongue; _c_, labial palp; these three together forming
-   the labium, or lower lip; _e_, eye; _f_, antennae. Above the
-   maxillae, or lower jaws (_d_ _d_), are shown dissected out:
-   _d^1_, inner or palpiform lobe; _d^2_, maxillary palp; _d^3_,
-   lacinia or blade; _d^4_, the palpifer or piece that bears the
-   palp (_d^2_); _d^5_, stipes or stalk; _d^6_, the cardo or hinge.]
-
-Now we may pass to the mouth parts. It will be good practice to dissect
-these out, either in air or in water. We may hold a Beetle between the
-finger and thumb of the left hand, and separate all the parts with a
-needle held in the right. It is a good plan to gum these parts on a
-card, for comparison with the figures in our favourite book--whatever
-that may be--on Natural History, and also with the mouth parts of
-insects of other Orders. For however much these may differ in form,
-and in the uses to which they are put, they are really modifications
-of the same parts.
-
-In Fig. 21 we have the upper side and in Fig. 21A the under
-side of the head represented, so that we may easily get acquainted
-with the different parts, and the names given to them. The cut should
-be gone over several times, and the parts in the picture compared with
-those in the specimen under consideration. It is good practice to
-endeavour to draw what is seen from the specimen itself, and then to
-compare the result with the work of the trained artist. And the mouth
-parts of Dytiscus may be compared with the mouth parts of the Cockroach
-(Fig. 33).
-
-  [Illustration: FIG. 22.--Disposition of mouth parts.]
-
-Returning to practical work, the first thing is to separate
-the _labrum_, or upper lip, from the head. Then the large
-_mandibles_ should be dissected out, and cleaned (by soaking in
-caustic potash) from the muscles which will come away with them. Behind
-these are a smaller pair of jaws, the _maxillae_, furnished with
-a pair of palps, called maxillary palps from their position. These are
-to be dissected out; and then the lower lip, or _labium_, may be
-separated by passing a sharpened needle along the line where it joins
-the chin. The palps on the lower lip are called labial palps.
-
-When these parts are cleaned and dried, they should be gummed on card,
-as shown in Fig. 22, where the long lines represent the upper and lower
-lips respectively, and the shorter ones the mandible and maxilla of
-each side.
-
-So much for the head. Now we discover that what appeared to be the
-thorax, when we were looking at the upper surface of the Beetle, and
-what is called the thorax in descriptions of Beetles, is really but
-a portion of that region, which is seen to be divided into segments.
-The covering on the upper surface protects only the first segment,
-the middle and hinder ones being covered by the wing-cases and the
-_scutellum_ (a triangular piece jutting backward from the second
-segment, and meeting the suture). This is not represented in Fig. 17;
-but we may put in with our pen a tiny triangle, with its base towards
-the head, and its apex towards the tail--this will meet the case.
-
-The first segment bears no appendage above, but to the under side is
-attached the first pair of legs. The middle segment also carries a pair
-of legs, and on its upper surface are the wing-cases, to the under side
-of which, and to the body, the winglets are joined. The last segment
-bears the wings above, and the last pair of legs below, these being
-placed very far back, so as to give them greater power in propelling
-the animal through the water.
-
-It will be convenient to examine the legs next. First, however, it
-will be well to look at a normal leg of an Insect (the Cockroach), and
-learn the names of the different parts. First comes the _coxa_ (_a_) or
-haunch, next the _trochanter_ (_b_), then the _femur_ (_c_) or thigh,
-the _tibia_ (_d_) or shank, and the _tarsus_ (_e_) or foot, ending in
-a pair of claws. There are three pairs of legs in perfect Insects, and
-usually the same number in larval forms, though in some of these legs
-are entirely wanting.
-
-  [Illustration: FIG. 23.--Leg of Cockroach.]
-
-In the males of the Margined Water Beetle and many of its near
-relations the first pair of legs deserve special attention. The first
-three joints of the tarsus have coalesced to form a disk or cup, which
-in our specimen bears two smaller ones on its inner surface. A power
-of 20 will show the disk nearly as well as it appears in Fig. 24.
-The purpose of this disk, or clasper, which is absent in females, is
-obvious. It was formerly supposed to act as a sucker, but Professor
-Lowne and Professor Miall[12] have shown that it does not act by
-atmospheric pressure, but by a viscid secretion discharged from the
-cup-like hairs with which the inner surface is set.
-
-  [Illustration: FIG. 24.--Tarsus of Dytiscus (magnified).]
-
-The middle pair of legs in the male also bear cup-like hairs on the
-corresponding joints of the tarsus, and in very much greater number.
-Professor Miall quotes Simmermacher to the effect that while the large
-disk on the fore-leg has 170 sucking-hairs, the enlarged joints of
-the tarsus of the middle leg bear no less than 1590. These hairs are
-plainly discernible with the half-inch Steinheil, and I have made them
-out with the inch, and think that I could show them to anybody else
-with that power. I have not looked for these sucking-hairs on the
-middle leg of other Beetles of the same family which have disks on
-their fore-legs, but they do exist in some other genera.
-
-If we watch a male Dytiscus in life, in a small aquarium, we shall soon
-be convinced that Lowne and Miall are correct in their statement that
-the cup-hairs discharge an adhesive substance. We shall see this all
-the more plainly if there is much floating vegetation. For, in swimming
-about, the Beetle will often come in contact with some of this, and it
-will adhere to the cup-hairs. His struggles to free himself from the
-encumbrance will show that the attachment is not altogether under his
-control. The offending weed is rubbed against the spines of one of the
-other legs till it is removed.
-
-  [Illustration: FIG. 25.--Female Dytiscus swimming.]
-
-The spines with which the legs are set are worthy of a good deal of
-attention, and, like the adhesive cup-like hairs, though in different
-fashion, they doubtless assist the animal in holding its prey. The
-first and middle legs end in strong claws; those of the last pair are
-not so well developed.
-
-The last pair of legs are the swimming organs. The tibia and tarsus
-are fringed with long stiff hair behind, so as to hold the water
-when the Beetle swims. A peculiar arrangement of the first joint of
-the tarsus allows the edge to be presented to the water when the limb
-is carried forward for the return stroke, thus offering the least
-possible resistance. This Dr. Sharp has compared to the action of a
-rower in feathering his oar. There is, however, this difference, which
-it is well to note. The oar is feathered after the stroke; the Beetle
-feathers its legs before the stroke. It is the first motion when it
-begins to swim, and the action is not peculiar to the male.
-
-We now come to the third region, the abdomen. Like the thorax it is
-visibly divided into segments, though the division between them is
-not so great. Much difference of opinion exists as to the number of
-segments in the abdomen of a typical insect. Some authorities maintain
-there are eleven, while others put the number as low as five. This,
-however, is theoretical rather than practical. It is enough for us
-to know that the number apparently varies greatly, owing to the
-coalescence of two or more of the segments.
-
-  [Illustration:
-
-   FIG. 26.--Upper surface of abdomen of typical Beetle.]
-
-The head in Insects, we have seen, carries the eyes, antennae, and
-feeding organs. The thorax bears the legs and wings. The abdomen bears
-no appendages, except in some cases, on the last segment; these are
-called _cerci_. It may be, however, that the stings of bees and
-the ovipositors of saw-flies and other insects are modified appendages.
-
-On examining the abdomen of Dytiscus we shall probably be struck with
-the difference in appearance between the upper and the under surfaces.
-The latter is hard, smooth, and shiny; the former, when the wings are
-removed, is seen to be covered with felt-like hair.
-
-Our interest is with the upper surface. Along the abdomen on each
-side lie spiracles, stigmata, or openings to the breathing tubes. The
-first and last are larger than the rest, and their general form can be
-readily made out with an inch magnifier, and with the half-inch we may
-get some idea of the detail shown in Fig. 27.
-
-  [Illustration: FIG. 27.--Spiracle of Dytiscus
-  (magnified).]
-
-Dytiscus breathes in this way. Floating up to the top of the water,
-the end of the abdomen projects above the surface. If one watches the
-Beetle the wing-cases will be seen to rise a little. The air retained
-by the felted hairs is given off, and a further supply taken in. Then
-the wing-cases are lowered again; the Beetle gives two or three strokes
-with its swimming legs, and descends below the surface to ramble round
-the tank in search of food.
-
-  [Illustration: FIG. 28.--Tracheal tubes (magnified).]
-
-This air-supply between the wing-cases and the abdomen is taken in at
-the spiracles and distributed through the tracheal tubes throughout
-the body. These tubes branch and subdivide till they end in small
-twig-like vessels comparable to the capillaries of the human body.
-They consist of two layers--the inner strengthened by what probably is
-a spiral fibre, though Packard believes that, in some cases at least,
-it consists of similar rings. But we must not pursue this subject. It
-would lead us beyond our appointed limits.
-
-       *       *       *       *       *
-
-Another Beetle fairly common in stagnant waters round London and in
-the southern counties is that to which the name Great Water Beetle
-(_Hydroph´ilus pic´eus_) of right belongs. This name is sometimes
-wrongly applied to Dytiscus, with which its rightful owner has
-little in common, except its aquatic habitat. Its scientific name is
-_Hydrophilus piceus_; but we shall speak of it as Hydrophilus.
-
-It is not a very easy matter to take this Beetle with a net, by
-sweeping in the ordinary way, for it likes to get into the middle of
-a mass of vegetation, where it is sure of a good food supply, and is
-probably safe from the attacks of Dytiscus, who not unfrequently makes
-a meal of his larger relation. A good plan is to pass the net under a
-mass of weed and then shake it to and fro in the water. By this means
-any Beetles in the weed will be dislodged from their hiding-places, and
-fall down into the bottle.
-
-They have, in confinement, the same habit of making a snug place
-for themselves; and more than once I have fancied that a Beetle of
-this species had escaped from the aquarium, when all the time it was
-hidden in a thick patch of water-moss. They are practically vegetable
-feeders, though Dallas says that they are not such strict vegetarians
-as to deny themselves a meal of animal food when they meet with a dead
-mollusc or larva in the course of their wanderings. I have never known
-them to indulge in animal food, dead or living, but I have known them
-refuse it.
-
-Hydrophilus is the largest British Water Beetle, and, with the sole
-exception of the Stag-Beetle, the largest British member of the Order.
-Its total length is very little less than two inches, and across the
-middle of the back it measures about half as much. It is more slenderly
-built than Dytiscus, and the contrast in the size and armature of the
-legs is very striking (Fig. 29). There is also a great difference in
-their method of progression through the water. Dytiscus moves both legs
-simultaneously, while Hydrophilus walks rather than swims, moving one
-leg after the other.
-
-If we cannot collect this Beetle for ourselves--which we should
-endeavour to do, if possible--it may be bought of almost any dealer
-in what are called ‘aquarium requisites.’ But prices rule higher
-for Hydrophilus than for Dytiscus. Bateman says that this species
-is rarer than formerly, and that specimens cost from 1_s._ to
-2_s._ 6_d._ a pair, ‘according to the dealer and the season.’
-From this I gather that I must have gone to a shop where the prices
-were reasonable, for I have never paid more than 6_d._ for a
-Hydrophilus, and then have been allowed to pick out a male. At the same
-shop I have paid 2_d._ for Dytiscus.
-
-  [Illustration: FIG. 29.--Great Water Beetle. _a_,
-  male; _b_, female; _c_, larva; _d_, pupa.]
-
-In keeping this Beetle we shall need a larger vessel than was required
-for Dytiscus. (In both cases the aquarium should be covered, for if
-food be scarce, and sometimes for other reasons, both these Beetles
-may take to flight.) The aquarium should be well supplied with growing
-water-weed, but none that is choice or valuable should be put in, for
-in moving about over the weed the animal will damage almost if not
-quite as much as it eats. This difficulty can be easily got over by
-supplying it with anacharis, water-crowfoot, milfoil, or any other
-common plant that grows rapidly and is easily procurable.
-
-The only specimen that I have taken myself was captured a few miles
-north of London. It exhibited a strange instance of depraved appetite.
-In the large tank into which it was put were growing vallisneria,
-frog-bit, and water-crowfoot in plenty. These it was never seen to
-touch. The tank, at one time, had been used for newts, and floating
-on the surface was a piece of virgin cork. It had served the former
-inmates as a kind of island continent, and had never been removed. To
-the under side of this the Beetle would moor himself, head downwards,
-and nibble away, as if cork were the natural diet of a British Water
-Beetle.
-
-In a few days the Beetle died. It was put into spirit, and soon after
-became the subject of a post-mortem. But its strange diet was not the
-cause of its death, which was sufficiently accounted for by injuries
-inflicted before its capture, probably by a larval or an adult Dytiscus.
-
-It would be mere waste of time to go over this Beetle and describe it
-point by point, as was done with Dytiscus. If what was there written
-was of any value, readers will be able to apply for themselves the
-method laid down. There are, however, some points of difference to
-which it will be well to invite attention.
-
-It is a good plan to lay specimens of these Beetles side by side
-for comparison. Hydrophilus is the larger of the two; and differs in
-colour as well as in size. Its hue is black with an olive tinge; and
-in certain lights a blue-black metallic gloss may be seen on the outer
-margins of the wing-cases. These are marked with faint longitudinal
-lines, and each bears three rows of dots running in the same direction.
-
-The greater length and more slender build of the legs of Hydrophilus
-are at once apparent. There is also a marked difference in the tarsal
-joints of the fore-legs of the male. The disks and cup-like hairs of
-Dytiscus are absent in Hydrophilus, but in their stead the last joint
-bears a sub-triangular plate, studded on the inner surface with spines,
-which probably serve a similar purpose. A great deal of valuable
-information about organs of this kind and their functions will be
-found in chapter X of Darwin’s _Descent of Man_. Simmermacher’s
-paper[13] should be consulted by all who have the opportunity. Our inch
-magnifier will show us these spines quite clearly; and also a curious
-little bunch of bristles, which Simmermacher says are probably organs
-of touch.
-
-It is a good plan to take Hydrophilus out of the water, and lay it upon
-its back, so that the difference between it and Dytiscus may be clearly
-seen. The Beetle should be handled carefully, for on the thorax is a
-kind of keel, ending in a sharp spine, which extends over part of the
-abdomen. This spine is free, and may easily wound the hands of those
-who do not watch the motions of the creature pretty carefully. The fore
-part of the abdomen and the thorax are covered with short close hairs,
-and when the Beetle is in the water these parts entangle a layer of
-air, which gives it the appearance of being covered with quicksilver.
-
-The two Beetles differ also in their method of exchanging impure for
-pure air. Dytiscus, as we have seen, takes in a fresh supply under
-its wing-covers behind; Hydrophilus takes in a fresh supply in front,
-employing for this purpose the antennae, which apparently do not
-function as feelers, as is generally the case.
-
-When Hydrophilus wants to take in a supply of pure air, it rises to
-the top of the water, slowly and deliberately. Unlike Dytiscus, it
-is never in a hurry. Then one of the antennae is pushed through the
-surface film, thus communicating with the air, which descends to the
-hair-covered thorax, whence it reaches the spiracles on the upper
-surface of the abdomen. To allow of this the wing-cases are slightly
-raised in front. The spiracles in Dytiscus are larger at the posterior
-end of the abdomen: in Hydrophilus the largest spiracles are in front.
-This is what might be expected, from the method adopted in each case
-for procuring a fresh supply of air.
-
-These Beetles have frequently bred in confinement; but no better
-account than that of Lyonnet has ever been given of the operation of
-the female in making her cocoon and depositing her eggs. As his account
-is not generally available, a condensed translation of it is inserted
-with his illustration.
-
-  [Illustration: FIG. 30.--Female Hydrophilus constructing
-  a cocoon. (After Lyonnet.)]
-
-Lyonnet[14] wanted to find out how the female made the cocoons (Fig.
-30), and this is how he set to work. He put some of these Beetles into
-a large aquarium, with a good quantity of water and some duckweed.
-On May 31 and the following day he noticed that one of the females
-was swimming about in every direction, as if in search of something.
-Thinking that this was because she had not the proper materials for her
-work, he then put into the aquarium some thread-like alga of a kind
-which he had seen attached to some cocoons, and on June 3 the Beetle
-began to make a cocoon, but soon gave up the task, apparently because
-she was troubled by other aquatic insects which had made a home in this
-weed. These intruders were removed, and the Beetle set to work once
-more. Lyonnet then noticed that, like a spider, she had her spinning
-apparatus at the posterior end of the body. She extended the last
-segments slightly, and opened the hindmost one, when he saw a nearly
-circular opening, in which was a whitish disk (Fig. 30A,
-_a_). On this disk were two little brown tubercles side by side,
-nearly at right angles to the longitudinal axis of the body. From each
-there projected a blackish-brown conical tube, about a line long, stiff
-towards the base, but flexible and elastic towards the tip. These tubes
-were the spinnerets, which acted together with a parallel movement, and
-from each proceeded a separate thread.
-
-And this is how she made her cocoon. She lay near the surface of the
-water back downwards, the under part of the body and the second and
-third pair of legs buried in the thread-like weed. The front legs were
-free, and with these she shaped the weed over her abdomen. Then she
-spun a covering of white silk against the under side of the weed. While
-she was spinning, from time to time she used her front legs to press
-and flatten the work against her body (Fig. 30B), giving it
-the shape of a flattened arch, to which her body gave the requisite
-curve. This, forming the top of the cocoon, was finished in about half
-an hour. Then she turned (Fig. 30C), and spun the bottom of
-the cocoon, moulding this, like the top, on the curve of her abdomen,
-and uniting the top and bottom with silk which she spun. The work
-occupied about an hour and a quarter.
-
-The Beetle then remained nearly in that position for some two hours. At
-first she was hidden in the cocoon quite up to the thorax. The body,
-however, was withdrawn almost imperceptibly. During this time she was
-busy laying her eggs in regular order, with the pointed ends upwards.
-
-After this she came out of the cocoon, and closed the mouth (Fig.
-30D), making the opening smaller by degrees. Then she made a
-little mast (Fig. 30D, _b_), of the use of which Lyonnet
-admits his ignorance, suggesting, however, that its construction may
-serve to use up the silky matter remaining after the work is finished,
-lest it should acquire harmful qualities in the body of the Beetle. The
-true explanation seems to be that it serves to convey air to the eggs
-inside the cocoon.
-
-On July 17 Lyonnet was rewarded for his patient watching by seeing
-a larva come out of the cocoon, and the next day some fifty more
-appeared. What he saw and recorded it is in the power of others to see,
-if they will imitate his patient observation.
-
-The Cocktail Beetle, or Devil’s Coach Horse (_Ocypus olens_), is
-an excellent specimen of a Land Beetle to examine, for it is of fairly
-large size and extremely common. Moreover it does well in captivity, so
-that there will be no difficulty in watching its habits in life, and
-pickling it for closer examination when dead.
-
-During the day these animals usually lie concealed under stones or
-pieces of earth, coming forth at dusk and during the night in search
-of food. Occasionally, however, they may be met with in daylight,
-leisurely stalking a smaller beetle or a fly; then with a dash seizing
-the victim in their powerful mandibles, which are quite capable of
-making an impression on the human skin, as those who handle these
-Beetles unwarily will discover for themselves.
-
-  [Illustration: FIG. 31.--Cocktail Beetle. _a_,
-  larva; _b_, pupa.]
-
-Nothing of an animal nature comes amiss to them, and if they cannot
-capture living prey, they will make a hearty meal off carrion. This is
-an advantage to us, for we may feed our captives with dead insects or
-with small pieces of meat.
-
-This Beetle is about an inch long, and of a deep dull black colour.
-The head is joined to the thorax by a distinct neck, and the abdomen
-is naked, owing to the fact that the wing-cases are very short. Its
-wing-cases bear about the same proportion to those of the Margined
-Water Beetle that a man’s frock-coat bears to a boy’s Eton jacket. And
-this Beetle may be taken as a good type of a group--the Beetles with
-short wing-cases (_Brachel´ytra_).
-
-The attitude of this animal when irritated or alarmed is well depicted
-in Fig. 31. It raises its head menacingly and opens its strong
-mandibles to their full extent, at the same time turning up the end of
-the abdomen, like a scorpion about to sting. From the last segment it
-will often put forth a pair of white vesicles, from which is discharged
-a volatile liquid of disagreeable odour, that probably acts as a
-defence against insect-eating creatures.
-
-The best way to capture one of these Beetles is to pick it up with what
-Kirby calls the ‘natural forceps’--the finger and thumb. It may be
-dropped into any convenient receptacle; the small metal boxes in which
-vestas are sold will answer the purpose very well.
-
-My specimen was given me by a friend, who kept it with another in a
-round tin box. It lived with me for about three months in a four-ounce
-bottle, that measured three inches in height, to the neck, and two
-inches in diameter. The bottom was covered to the depth of about an
-inch with garden soil, and the top tightly corked, to prevent the
-prisoner’s escape. This precaution was necessary; for the inside of
-the bottle, though cleaned from time to time, soon became covered with
-a coating of earthy particles, which afforded the Beetle a pretty firm
-foothold.
-
-It was an extremely interesting pet, and its struggles to escape
-by climbing up the sides of the bottle often afforded me much
-entertainment. It seemed to have a glimmering notion that the only
-way out was by the top, and knowing nothing of the cork it would rear
-itself up against the side, and try to climb up by vigorous movements
-of its fore-legs. It would also take advantage of any little lump of
-earth projecting about the rest. It had not intelligence enough to make
-anything like a mound for itself, though the inequalities were probably
-the result of its burrowing under the surface. Its temper was none of
-the best, for if it was disturbed with the forceps it would resent it
-fiercely. The mandibles would be opened, the abdomen curled up, and out
-would come the two vesicles as a means of defence. If the forceps were
-put near the mandibles, they would be seized, and the Beetle would hold
-on so tenaciously that it has often been lifted out of its bottle in
-this fashion.
-
-It was exceedingly voracious, and was generally fed on garden worms.
-After a full meal its increase in size was very evident. This is not to
-be taken to mean that insects grow after they have attained the perfect
-or imago state, for this is not the case. But when they have had a long
-fast, the segments approach each other, and are forced apart when the
-creature is gorged with food. If a Beetle of this species were kept
-fasting for some days, and then carefully measured, and measured again
-after being plentifully supplied with worms or flies, there would be a
-difference of some millimetres between the results.
-
-Dallas has an interesting passage in his _Elements of Entomology_
-respecting the boldness of the larval form, which is worth quoting.
-‘I have seen one engaged in a struggle, which lasted about twenty
-minutes, with a worm of some five inches in length, the larva being
-scarcely more than an inch long. During this contest the little savage
-crept under the worm, fixing his mandibles into the creature’s body in
-various places, each bite apparently producing a considerable swelling.
-Sometimes he would fasten upon the head of the worm, and retain his
-hold with the pertinacity of a thoroughbred bulldog, although twisted
-about in every direction by the struggles of his intended victim. At
-last, however, he seemed to come to the conclusion that he had been
-too ambitious in his desires, and went quietly off amongst the grass,
-rather prematurely, as it seemed to me, for when the worm began slowly
-to leave the field of battle, about an inch of his tail was attached to
-the rest of his body solely by the intestine, a union which the jaws of
-the larva would easily have dissolved.’
-
-I have never seen a fight between a larva and a worm, for the few larva
-I have kept have been fed on flies. But the adult Beetle which has once
-fastened on a worm cannot be shaken off. It will grip its prey with the
-first pair of legs, fixing the claws in the skin, and will finish a
-worm three inches long at a meal.
-
-A dead specimen should be looked over in the way recommended for
-Dytiscus, raising the small wing-covers and unfolding the wings. The
-spiracles are to be looked for at the sides of the abdomen, in the
-groove formed by the meeting of the upper and under plates of each
-segment. The short downy hair with which the body is covered should
-be noticed, and the front legs are well worth examination. The tibia
-or shank is armed with a strong spine, and between this part of the
-leg and that which follows it is a notch, through which the Beetle
-passes its antennae to clean them from dirt. The peculiar shape of
-the joints of the tarsus or foot is very plainly discernible with the
-appliances at our command, and by a careful management we may make out
-the different kinds of hairs with which four out of the five of these
-joints are furnished; some stout and spine-like, others finer, ending
-in a pear-shaped bulb. These last probably serve the same purpose as
-the sucking-disks of Dytiscus and the tarsal plates of Hydrophilus.
-
-
-
-
-                              CHAPTER III
-
-        COCKROACHES; EARWIGS; THE GREAT GREEN GRASSHOPPER; THE
-                  WATER SCORPION; THE WATER BOATMAN;
-                                CORIXA.
-
-
-The next insect to come within range of our pocket lens is the Common
-Cockroach (_Blatta orienta´lis_[15]), popularly misnamed the
-Black Beetle. We shall have no difficulty in procuring material for
-examination. Housekeepers will tell us that these creatures are only
-too plentiful.
-
-In the last chapter we dealt with Sheath-winged Insects--the
-Coleop´tera. Cockroaches belong to the Orthop´tera, or Insects with
-Straight Wings. The mouth-parts resemble those of Beetles. The chief
-differences that mark off the Cockroaches and their kin from the
-Beetles are the incomplete metamorphosis which the former undergo, and
-the character of the wings. Straight-winged Insects, when they leave
-the egg, differ little in shape from the adult, except in the fact that
-they have no wings; and these appendages are absent, or so small as
-to be useless for flight in many species. When wings are present the
-first pair are of little or no use for flight. They are not, however,
-hard chitinous sheaths, meeting in the middle line--that is, straight
-down the centre of the back--but of a flexible leathery or membranous
-substance, and they usually overlap each other at the tips. The hinder
-wings are large and nearly semicircular. The principal veins radiate
-from the centre to the circumference, like the sticks of a fan, and
-when the wings are folded up they lie straight along the upper surface
-of the abdomen. It is from this fact that the Order derives its name.
-
-There are two great groups, or sections, of Straight-winged
-Insects--those that run, like the Cockroaches, and those that leap,
-like the Grasshoppers. No Straight-winged Insect is aquatic.
-
-The Common Cockroach, now so abundant, is not a native, but an
-importation from Asia; though how it reached this country is not quite
-certain, probably by way of Holland. It seems to have established
-itself in London by the end of the sixteenth century, and some two
-hundred years later we find Gilbert White recording (in or before 1790)
-that ‘a neighbour complained that her house was overrun with a kind of
-black beetle, or, as she expressed herself, with a kind of black-bob,
-when they got up in the morning before daybreak. Soon after this
-account I observed an unusual insect in one of my dark chimney closets,
-and find since, that in the night they swarm also in my kitchen....
-The male is winged, the female is not, but shows something like the
-rudiments of wings, as if in the pupa state.... They are altogether
-night insects, _lucifugae_, never coming forth till the rooms are
-dark and still, and escaping away nimbly at the approach of a candle.’
-
-This description leaves no doubt as to what the ‘black-bobs’ really
-were. This name seems to have dropped out of use, and it would be well
-if ‘black beetle,’ in the sense of Cockroach, were also allowed to
-drop, for the term contains just as many errors as words.
-
-We may make our first acquaintance with these insects by keeping some
-specimens in confinement. A tin box, with a glass lid, will make a
-capital dwelling for them. Some paper should be put in, for them
-to hide in away from the light, and there can be no difficulty in
-providing them with food. ‘Bark, leaves, the pith of living cycads,
-paper, woollen clothes, sugar, cheese, bread, blacking, oil, lemons,
-ink, flesh, fish, leather, the dead bodies of other cockroaches,
-their own cast skins and empty egg-capsules, all are greedily
-consumed. Cucumbers, too, they will eat, though it disagrees with them
-horribly[16].’
-
-We have Dr. Sharp’s authority for the statement that in confinement
-these insects are rather amusing pets, as they ‘occasionally assume
-most comical attitudes, especially when cleaning their limbs. This they
-do somewhat after the fashion of cats, extending the head as far as
-they can in the desired direction, and then passing a leg or an antenna
-through the mouth; or they comb other parts of the body with the spines
-on the legs, sometimes twisting and distorting themselves considerably
-in order to reach some not very accessible part of the body[17].’
-
-The prejudice against these insects is, however, so strong, that most
-people will prefer to examine dead rather than living specimens, on
-account of the disagreeable odour of the latter. This odour is due to
-a fetid excretion from the mouth, and if the specimens are killed by
-dropping them into boiling water, this will be discharged, and after a
-little while they may be taken out with a pair of forceps, and put into
-spirit for preservation. If they are dropped alive into spirit, the
-excretion will communicate its strong scent to the preserving medium,
-and this should be changed before the insects are examined.
-
-From Fig. 32 we may get a general idea of the appearance presented by
-a male or female, lying back upwards in a small glass dish, ready for
-examination with the pocket lens. The female may be distinguished at a
-glance by her wingless condition--only rudiments of wing-cases being
-present, and no wings--and her broader abdomen. In life she does not
-stand so high upon her legs as does the male, and her abdomen trails
-along the ground. The male does not acquire his wings till the last
-moult.
-
-  [Illustration:
-
-    _Female._      _Male._
-
-    FIG. 32.--Cockroaches.]
-
-As the Cockroach lies back uppermost in a glass dish, the head is
-almost concealed. This is especially the case, unless the insect is
-flattened out in some way, or pinned down to a piece of weighted cork.
-There will thus be, apparently, two, instead of three main divisions.
-This arises partly from the fact that the head is deflexed, or bent
-down so that the mouth is turned towards the rear, and partly because
-the first segment of the thorax bears a chitinous shield, roughly
-semicircular, which covers so much of the head as would otherwise be
-visible.
-
-The difficulty, however, may be easily got over, by reversing the
-position of the insect, and raising the head with a needle. The
-antennae will attract attention by their great length. In the male
-insect they exceed, while in the female they fall a little short of,
-the total length of the body. They are well worth examination. Even a
-low power will show that they consist of a number of joints--usually
-from seventy-five to ninety. The three basal joints are much larger
-than the rest, and in the female the third basal is nearly as long as
-the first. All these joints are thickly set with stiff hairs directed
-forwards. At the outer side of each antenna is a compound eye, and on
-the inner side is a pale spot, the _fenestra_, which in the males
-of some foreign Cockroaches is replaced by a simple eye.
-
-If Cockroaches are kept in confinement, and forced out into the light,
-the constant motion of the antennae will satisfy the observer that they
-are of great use to their owners. By means of these organs they not
-only discover their food, but become by some means, probably by the
-motion of air-waves, aware of danger that threatens them. Belt, in his
-_Naturalist in Nicaragua_ (p. 110), speaking of the Cockroaches
-that infest houses in the tropics, says, ‘They are very wary, as they
-have numerous enemies--birds, rats, scorpions, and spiders; their long,
-trembling antennae are ever stretched out, vibrating as if feeling the
-very texture of the air around them; and their long legs quickly take
-them out of danger.’ It is not given to every one to visit the tropics,
-but we may all use our eyes in observing the common insects that abound
-in our country, and in doing this we shall strengthen the habit of
-observation, and very often find confirmation of what we read of the
-habits of insects in distant lands.
-
-Sir John Lubbock[18], in treating of the sense of smell in Insects,
-says that ‘Plateau put some food of which cockroaches are fond on a
-table, and surrounded it with a low circular wall of cardboard. He then
-put some cockroaches on the table: they evidently scented the food,
-and made straight for it. He then removed their antennae, after which,
-as long as they could not see the food, they failed to find it, even
-though they wandered about quite close to it.’
-
-The large kidney-shaped compound eyes are sure to attract attention.
-It is worth while to take out and break up an eye, gently washing out
-the pigment. If we do this, and then examine it with the pocket lens,
-we shall have some idea of the multiplicity of lenses in the eye of a
-Cockroach, each of the six-sided facets being a lens.
-
-Next come the mouth parts, which may be run over very quickly, for
-those of Beetles are formed upon the same plan, and from this primitive
-plan are derived the mouth parts of all other Insects, of whatever
-character they may be. To examine the mouth organs the insect must be
-turned on its back, and the _labrum_ (_a_), or upper lip,
-raised with a needle, so as to allow of a general view of the rest.
-Then the jaws or mandibles (_b_) may be picked out with a needle.
-These jaws are strongly toothed, and work from side to side, and it
-is easy to see that they are very efficient organs. The lower jaws
-(_c_), or _maxillae_, lie below, and are compound organs,
-each being made up of several parts--the base, called the _cardo_
-or hinge (not shown in the illustration, but connected at right angles
-by a joint with the lower part, the _stipes_). From the stipes
-rise the _galea_, or helmet, on the outer side; and, on the
-inner side, the _lacinia_, to which the name maxilla is often
-applied, though it properly belongs to the whole. At the base of the
-_galea_ is inserted the five-jointed maxillary palp, thickly set
-with hairs, and probably an organ of touch.
-
-  [Illustration: FIG. 33.--Mouth parts of a Cockroach.]
-
-By examining the maxillae (_c_) before they are separated, and
-comparing them with the _labium_ (_c_) or under lip, which closes the
-mouth from below, it will be evident that there is no slight similarity
-between them. Nor is this strange: for the under lip consists of the
-second maxillae joined at their bases, which form the _submentum_ (_s_)
-and _mentum_ (_m_). (The former is the small, the latter the large
-white basal portion; the vertical line in the illustration shows the
-mental suture, and should be traced in the dead insect.) The organs in
-the centre constitute the _ligula_; and on each side of the labium is a
-three-jointed palp (_labial_), like that on the maxillae, thickly set
-with hairs, and with a similar function. It is well to work over the
-mouth parts a few times till the relation between the maxillae and the
-labium is seen and understood. The internal tongue (_d_) is attached to
-the inner side of the labium.
-
-Now, still working on the under side of the insect, the three segments
-of the thorax are to be made out, and one cannot fail to notice the
-great size of the first joint (the _coxa_) in all the legs, and
-that these joints seem to serve as shields to protect the under side
-of the thorax. Then the different parts of the legs should be traced,
-and compared with Fig. 23 on p. 44. The spiny armature of the tibiae is
-to be noticed, as are the claws, between which is a projecting lobe,
-though this is absent in immature specimens. We shall find that the
-appendages of the thorax are the same as in the Margined Water Beetle.
-It is well to take as little as possible on trust, and to verify
-everything that we possibly can.
-
-Now we may reverse the position of our subject, and having cut off
-the wing-cases, which are technically called _teg´mina_, examine
-the wings. These may be gently unfolded with a needle or a camel’s
-hair brush, when the longitudinal method of folding will be clearly
-seen, and the difference of the veining from that of the wings of
-the Margined Water Beetle will be apparent. A female should also be
-examined, and the small tegmina cut off, so as to see that not even the
-rudiments of wings are present.
-
-The Cockroach breathes like other adult Insects, and the spiracles
-are ten in number--two on the thorax and eight on the abdomen. The
-thoracic spiracles may be pretty readily seen, but those on the abdomen
-are not so easy to make out. But by cutting away, with a fine pair
-of scissors, the edges of the plates that cover the upper and under
-surfaces of the abdomen and the membrane that unites them (Fig. 34), we
-may discover them as the open ends of small tubes. While dealing with
-the insect in this fashion, it will be easy to take out a piece of the
-tracheal tube, which may be compared with Fig. 28.
-
-  [Illustration: FIG. 34.--Cockroach, showing Spiracles.]
-
-The abdomen consists of a series of rings or segments, the exact number
-of which is rather difficult to decide, from the fact that some are
-concealed and others altered in form. Dr. Sharp[19] says that ‘it is
-considered that ten dorsal and ten ventral plates exist, though the
-latter are not so easily demonstrated as the former.’ In the male, ten
-above (dorsal) and nine below (ventral), and in the female two less in
-each case, may be made out without dissection.
-
-From the sides of the tenth segment two organs, the _cerci_
-(Fig. 35, _a_), are given off, one on each side. These may be
-distinguished from the styles of the males by their presence in both
-sexes. Our inch lens will show that each cercus consists of sixteen
-rings. If we use the half-inch, we shall see that each ring is set with
-hairs of different lengths.
-
-When we have got so far it may be well to compare the structure of
-a _cercus_ with that of an antenna (p. 67). In each we have a
-succession of jointed rings giving flexibility to the organ, and the
-rings in each case are studded with hairs. It has been shown pretty
-conclusively--and we may verify the experiments--that the antennae are
-sense-organs. Are we not justified in coming to the conclusion that,
-since the antennae and the cerci resemble each other in structure,
-they also resemble each other in function? If the Cockroach receives
-sensations by means of the antennae, is it not probable that it also
-receives sensations by means of the cerci?
-
-Having worked over the Cockroach from the outside, it will be
-advantageous to get some acquaintance with its internal anatomy.
-This is not a difficult matter. The specimen is to be pinned down,
-under water, with its back uppermost. The wings having been removed,
-a longitudinal cut is to be made down the centre from the posterior
-part of the abdomen to the back of the head, and the two sides of the
-integument turned back. Or the junction between the upper and lower
-plates on each side may be cut through with a cutting needle, and the
-whole integument removed.
-
-The first task is to clear away the fat-body, a whitish substance
-which overlies the chief organs of the body. When this is picked to
-pieces and floated off the digestive system will be exposed. After
-this has been worked over a few times there should be no difficulty in
-dealing with similar parts in other Insects. At the back of the head
-lies the gullet or oesophagus leading into the crop (_c_), at the
-base of which lies the gizzard (_g_). The interior of this organ
-is furnished with six strong chitinous teeth, with small ridges of
-the same substance between them. Towards the posterior end are six
-cushions, all set with fine bristles. Behind this comes the stomach
-(_v_), into which open seven or eight tubes, closed at one end,
-and between it are the Malpighian tubes, which are concerned in the
-process of excretion. The small intestine (_co_) succeeds, and
-behind this is the rectum (_r_).
-
-  [Illustration: FIG. 35.--Alimentary Canal of Cockroach.]
-
-It will be interesting to separate the gizzard from the crop (_c_)
-and stomach (_v_) and break it open with a couple of needles, so
-as to examine the teeth, which will be more easily made out if the
-opened organ be allowed to soak for a time in a solution of caustic
-potash.
-
-Similar teeth-like processes are found in the gizzards of many other
-Insects, and their presence has given rise to some strange ideas.
-Swammerdam[20] says, ‘I preserve also the threefold stomach of a
-locust, which is very like the stomach of animals that chew the cud,
-and particularly has that part of the stomach called Echinus[21] very
-distinctly visible. I do not, therefore, doubt but locusts chew the
-cud, as well as the animals just mentioned. Indeed, I persuade myself
-that I have seen this.’
-
-Somewhat similar teeth-like processes exist in the Lobster, the Crab,
-and the Crayfish. ‘Professor Plateau has expressed a strong opinion
-that neither in the stomach of Crustacea nor in the gizzard of Insects
-have the so-called teeth any masticatory character.’ He adopts
-Swammerdam’s comparison, but considers them strainers, not dividers of
-the food[22].
-
-We may be fortunate enough to meet with some specimens of the American
-Cockroach (_Periplane´ta america´na_, Fig. 36), a much larger
-species, which has established itself in some few places in this
-country. At the Zoological Gardens, Regent’s Park, it is abundant, and
-has almost, if not entirely, driven out the common form. Mr. Bartlett
-believes that it was introduced in cases in which animals have been
-sent over from America. Both sexes are winged. They not only possess
-organs of flight, but use them. If one visits the Gardens, there will
-be no difficulty in getting specimens; and it is interesting to compare
-the points of agreement in and of difference between this animal and
-our common form.
-
-  [Illustration: FIG. 36.--American Cockroach (male).]
-
-The Earwig (_Forfic´ula auricula´ria_) is common enough to furnish
-us with plenty of specimens on which we may employ our pocket lens. Any
-garden in the summer months will yield an ample supply. Earwigs, like
-Cockroaches, are light-shunning insects, and love to hide themselves in
-the corollas of flowers; and it is probably from their habit of seeking
-to conceal themselves that they have acquired their bad reputation--by
-no means confined to our own country--of creeping into the ears of
-persons lying asleep, and causing death by getting into the brain. Such
-an occurrence is beyond the bounds of possibility. No insect of this
-size could pass the drum of the ear.
-
-We may easily keep these insects and observe their movements, if we
-put them into a wide-mouthed glass bottle and supply them with food.
-They are extremely fond of the flowers of the dahlia; but a dahlia
-would offer too many hiding-places, so we will put into the bottle some
-nasturtium flowers, or any others with a bell-shaped corolla.
-
-If we get a colony in spring we may watch the care of the female for
-her eggs. According to Kirby and Spence[23], ‘she absolutely sits
-upon her eggs, as if to hatch them--a fact which Frisch appears first
-to have noticed--and guards them with the greatest care. De Geer
-(_Mémoires_, iii. 548) having found an earwig thus occupied,
-removed her into a box where was some earth, and scattered the eggs in
-all directions. She soon, however, collected them one by one, with her
-jaws, into a heap, and assiduously sat upon them as before. The young
-ones, which resemble the parents, except in wanting elytra and wings,
-... immediately upon being hatched creep like a brood of chickens
-under the belly of the mother, who very quietly suffers them to push
-between her feet, and will often, as De Geer found, sit over them in
-this posture for some hours.’ Mr. Kirby adds: ‘This remarkable fact I
-have myself witnessed, having found an earwig under a stone which I
-accidentally turned over, sitting upon a cluster of young ones, just as
-this celebrated naturalist has described.’
-
-Like the Cockroaches, Earwigs undergo an incomplete metamorphosis.
-When the young leave the egg they resemble their parents, as may be
-seen from the immature forms represented in Fig. 37. The resemblance
-becomes greater at each successive moult.
-
-  [Illustration: FIG. 37.--Larva and Pupa of Earwig.]
-
-In working over these insects, the forceps, or pincers, at the end
-of the abdomen will attract attention. They are found throughout the
-family, but little is known of their function. It is said that they
-are used to aid in folding the wings, and tucking them under the
-wing-covers. This can scarcely be their only function, for they are
-found in species that have no wings. Probably they serve as organs
-of defence and, to some slight extent, of offence. When the abdomen
-is curled up, these forceps certainly give the insect a threatening
-appearance. They cannot, however, do much harm.
-
-These forceps differ in shape in the male (Fig. 38) and female, the
-blades being almost close together in the latter. In the males they
-differ considerably in size. Of 583 mature males taken in one day in
-the Farne Islands, and examined by Messrs. Bateson and Brindley, the
-forceps varied in length from 2·5 mm. to 9 mm.[24] These are called
-respectively ‘low’ males and ‘high’ males. The latter are in all points
-larger than the former, and have been described as a separate species,
-‘but it was impossible to get reliable measurements of the total
-length, owing to the fact that the abdominal segments telescope into
-each other’ (cf. p. 30).
-
-After examining the antennae and dissecting out the mouth organs, the
-peculiar overlapping or imbrication of the plates of the abdomen
-should be looked for; and on the membrane that connects them the
-spiracles may be detected.
-
-The wings and the complex method of folding have led some systematists
-to rank the Earwigs as an Order, while some others rank them as a
-Sub-order. For the present, at any rate, we need not concern ourselves
-about this. It is enough for us to know that they are closely related
-to the Orthop´tera.
-
-As we look at the Earwig from above, the wing-cases recall to our mind
-those of the Devil’s Coach Horse (Fig. 31), though there is one great
-difference. From beneath those of the Earwig project two small leathery
-pieces which are absent in the Beetle. These pieces are not, as one
-might imagine, at the tips of the wings, but on the front margin, about
-halfway down, and is indicated in the illustration by the shading
-between the extremity of the wing-case and the crease-mark at _a_.
-
-  [Illustration: FIG. 38.--Earwig (male).]
-
-From the illustration we may understand how the Earwig opens and closes
-its wings. From the point _a_ veins, which are thickened about
-halfway down, radiate to the hinder edge of the wing, and a little
-beyond the thickening they are connected by a vein which runs parallel
-with the hinder edge. These radiating veins are brought together, so
-that there is a fan-like closing, like that of the Cockroach, but from
-a different centre. The wing is then folded back at the place where the
-veins are thickened, and then there is a second transverse fold at the
-point _a_, so that the only part of the wing now visible is the
-leathery patch, which projects beyond the wing-case when the wing is
-tucked away.
-
-It is not difficult to unfold the wing of a dead specimen, under water,
-using a needle and fine brush. Mr. E. A. Butler[25] recommends a simple
-but excellent plan for unfolding and preserving the wing, by gumming
-it, with the upper surface downwards, to a piece of card, and gradually
-unfolding it and fastening it down. This is not so easy as it may seem,
-but with patience and perseverance success will be obtained; and a
-similar method may be adopted with the wings of other Insects, which
-may be mounted in this way without any trouble. Thus they may be easily
-preserved for examination at a future time, or for comparison with the
-wings of other Insects.
-
-It is rather remarkable that an insect like the Common Earwig, which
-very rarely takes to flight, should have such a complex method of
-folding its wings. Dr. Sharp says that though the Earwig ‘is scarcely
-surpassed in numbers by any British insect, yet it is rarely seen on
-the wing. It is probable that the majority of individuals of this
-species may never make use of their organs of flight, or go through the
-complex process of folding and unfolding them.’
-
-Let us choose our next example from the Leaping Orthop´tera. They may
-be distinguished at a glance from their relatives that run, but do not
-leap, by the peculiar structure of the third pair of legs. These are
-much longer and stouter than the other two pairs, and the thigh is very
-muscular. This insect is a very good type of the family Locus´tidae, to
-which, however, none of the insects popularly called ‘locusts’ belong.
-They are included in another family (_Acridi´idae_), where the
-common British Grasshoppers are also placed. The Locustids and the true
-locusts may be distinguished by the difference in their antennae: in
-the latter these organs are short, in the former they are very long and
-delicate.
-
-The Great Green Grasshopper (_Locus´ta viridis´sima_) (Fig. 39) is
-fairly common all over the country, but often escapes observation from
-the fact that its hue corresponds so nearly to that of the foliage on
-or among which it lives. One specimen taken in a Devonshire lane gave
-me a great deal of trouble before it was secured and transferred to
-a small tube. It was perched on a leaf when I first saw it, and as I
-approached it leaped away. Though I was certain it had not gone far,
-it was some little time before I discovered it, and got near enough
-to grasp leaf and insect, in time to prevent the latter from taking
-another jump.
-
-This insect may be kept alive in confinement for a considerable time,
-and will do fairly well on a diet of leaves and fruit, though it will
-not refuse an occasional meal of flesh. Dr. Sharp says that a specimen
-in confinement ‘mastered a humble-bee, extracted with its mandibles
-the honey-bag, and ate this dainty, leaving the other parts of the
-bee untouched.’ It is said that if two be placed together in a box
-they will fight most desperately, and that the victor will make a meal
-off the body of its victim. De Geer witnessed a case of this kind in
-a closely allied species that is found in Sweden. Its specific name
-signifies ‘wart-eater,’ and commemorates the fact that the peasants
-incite these insects to bite their warts, firmly believing that warts
-once bitten speedily disappear, and do not grow again. Westwood says
-that one of these insects actually devoured part of its own leg that
-had been broken off accidentally. When the creature was seen at night
-the detached leg was whole; in the morning about half of it had been
-eaten.
-
-  [Illustration: FIG. 39.--Great Green Grasshopper
-  (female).]
-
-It is well to get specimens of male and female insects. We shall
-require the former in order to examine the sound-producing apparatus,
-which the females do not possess; and the latter for the sake of the
-ovipositor--a long scimitar-like organ by means of which the eggs are
-deposited. Let us take the female first. The length, including the
-ovipositor, is a little under two inches, and the antennae will measure
-about as much more. The wing-cases do not lie flat upon the back, as do
-those of the Cockroach, but in a slanting position, like the sides of
-a roof, forming a ridge in the centre. The head is not bent back, as
-in the Cockroach, nor does it project in front, as in the Beetles, but
-the front is almost vertical. The armature of the mouth is strong, and
-of the same pattern as that of the Cockroach. The hood--so the upper
-covering of the thorax is called--is of a peculiar shape, somewhat like
-that of a saddle. The wing-cases and wings, with their folding, will
-offer little difficulty. Next we may examine the cerci, and contrast
-them with those of the Cockroach and with the forceps of the Earwig.
-Last of all, the ovipositor must be examined, and its structure made
-out, so far as the means at our command will allow.
-
-Apparatus of this kind for placing eggs in positions favourable to
-their development is by no means confined to these insects, for
-examples may be found in other Orders. Sirex, the so-called Tailed
-Wasp, has a long straight one, which is often supposed to be a sting,
-and the insect itself is not unfrequently taken for a gigantic wasp or
-hornet.
-
-When the ovipositor of our subject is looked at with the unassisted
-eye, it appears to consist of two curved blades placed side by side,
-with an internal groove on each. The apparatus, however, is not quite
-so simple: it is made up of six chitinous rods, of which four--the two
-above, and the two central ones--are developed from the ninth segment
-of the abdomen, while the two lower ones spring from the eighth. It is
-not difficult to test these statements. Specimens are plentiful; and as
-the ovipositor in this insect is large, and easily broken up into its
-component parts, it may well serve as an introduction to the study of
-these organs in other Insects--the Saw-flies, for example.
-
-When the insect is about to deposit her eggs, she selects a spot where
-the soil is light, and bending the ovipositor nearly at a right angle
-to her body, thrusts it into the ground as far as possible. Then, by
-a muscular effort, the plates of the ovipositor are separated, and
-several eggs travel down the passage formed by the central pair of rods
-into the hole. This is repeated time after time, till the operation of
-egg-laying is completed. This takes place in the autumn, and the young
-emerge from the eggs in the spring. When they come out they are tiny
-copies of the adults; but they do not acquire wings till after several
-months. The ovipositor of the female appears after the second moult,
-and till this organ is developed no difference is apparent between the
-young insects.
-
-The chief interest of the male insect lies in its wings, for the first
-pair (the _teg´mina_) are the organs with which it produces its
-‘love-songs.’ Kirby comments on the fact that Lichtenstein, in the
-_Linnaean Transactions_ (iv. 51), ‘draws attention to the eye-like
-area in the right wing-case of the males of this genus,’ adding that
-that author seemed ‘not to be aware that De Geer had noticed it before
-him, as a sexual character; and also, with good reason, supposed that
-it assists these animals in the sounds they produce.’
-
-This is how De Geer (_Mémoires_, iii. 429) describes the
-sound-producing apparatus of the Great Green Grasshopper: ‘In our
-male grasshoppers, in that part of the right elytron which is folded
-horizontally over the trunk, there is a round plate of very fine
-transparent membrane, resembling a little mirror or piece of talc, of
-the tension of a drum. This membrane is surrounded by a strong and
-prominent nervure, and is concealed under the fold of the left elytron,
-which has also several prominent nervures answering to the margin of
-the membrane or ocellus. There is every reason to believe that the
-brisk movement with which the grasshopper rubs these nervures against
-each other produces a vibration in the membrane, augmenting the sound.
-The males in question sing continually in the hedges in the months of
-July and August, especially towards sunset, and part of the night. When
-any one approaches they immediately cease their “song.”’
-
-It is probably unnecessary to do more than remark that the noises made
-by Insects do not correspond to the voices of the higher animals. ‘For
-no insect, like the larger animals, uses its mouth for utterance of
-any kind: in this respect they are all perfectly mute; and, though
-incessantly noisy, are everlastingly silent[26].’
-
-Our plan with these wings is to first verify the fact of their bearing
-these talc-like spots, the serrated nervures on the right and the
-rudimentary file on the left elytron. The sound is produced by rubbing
-the base of the left elytron against that of the right. A recent author
-compares this insect to a fiddler, and says that the left tegmen is the
-bow and the right the fiddle.
-
-The last point to examine is the ear. It seems strange to say that
-these insects have ears in their legs; but though some of the older
-entomologists regarded these structures in the tibiae of the first pair
-of legs as nothing more than resonators or sound-boards to intensify
-their chirping, there is no doubt that they are really organs of
-hearing. Much interesting information on this subject will be found in
-Sir John Lubbock’s _Senses of Animals_.
-
-  [Illustration:
-
-   FIG. 40.--Tibial ear of Great Green Grasshopper.]
-
-These oval patches are plainly distinguishable by the unassisted eye,
-and correspond in function to the tympanum or drum of the human ear.
-The air-supply to the tibiae is distinct from that of the rest of the
-body, and is derived from a large orifice on each side of the first
-segment of the thorax. These orifices may be seen by removing the
-‘hood.’ Indeed, they cannot escape observation. From these orifices an
-air-tube passes to each leg, dividing into two branches in the tibia
-and reuniting below the drums.
-
-Dr. Sharp[27] says that ‘although the tibial ears of the Locus´tidae
-are very perfect organs, there is great difficulty in deciding on the
-exact nature of their functions. They would appear to be admirably
-adapted to determine the precise locality from which a sound proceeds
-... for the legs can be moved in the freest manner in every direction,
-so as to bring the drum into the most direct line of the vibrations.
-But as to what kinds of vibrations may be perceived, and the manner
-in which they may be transmitted to the nerves, there is but little
-evidence.’
-
-The next Order from which we shall choose examples will be the
-Hemip´tera, containing the Land and Water Bugs and some other forms.
-Our chief concern, however, is with the Water Bugs. In this Order the
-metamorphosis is incomplete; the mouth is adapted for sucking the
-juices of plants and animals; and there are usually four wings. In the
-Land and Water Bugs, part of the fore wings is harder than the hind
-wings; in the other winged members of the Order both pairs of wings are
-membranous. The front wings are called hemel´ytra or halfel´ytra, to
-distinguish them from the el´ytra or wing-cases of Beetles, which are
-chitinous throughout. Fig. 41 shows the hemel´ytron and hind wing of a
-Land Bug, and the names given to the different parts of the front wing.
-
-  [Illustration: FIG. 41.--A Land Bug (magnified).
-  _a_, corium; _b_, clavus; _c_, membrane.]
-
-The Water Scorpion (_Nepa cine´rea_) is not difficult to procure,
-or to keep in confinement when it is caught. It would be straining
-language to call it a handsome creature, yet it well deserves careful
-study, on account of the wonderful modification of the first pair of
-legs, and it is from the resemblance of these to the pedipalps of the
-scorpion that the insect derives its popular name. Its length is about
-an inch and a quarter, from the tip of the beak, or rostrum, to the end
-of the breathing-tube. Its greatest width is a little over a quarter of
-an inch (Fig. 42). The general hue harmonizes well with the mud, but
-the upper surface of the abdomen is a warm red, ‘and is thick set with
-hair, so as to afford a very agreeable sight.’
-
-  [Illustration: FIG. 42.--Water Scorpion.]
-
-It is extremely common in shallow pools, and its favourite haunt is
-near the shore, where it will lie, almost buried in the mud, with its
-raptorial legs elevated, ready to seize on any passing insect, and its
-breathing-tube just pushed through the surface-film. I learnt this
-habit of the insect on the first occasion on which I tried to collect
-specimens of it. I had been told that a certain piece of water swarmed
-with Water Scorpions. This, I afterwards found, was quite correct;
-but though I worked the pond from end to end, a single specimen was
-all that rewarded my labour. Whilst transferring the insect from the
-net-tube to the bottle for transport, a stranger joined me, and kindly
-volunteered his assistance. He had no collecting tackle, but in about
-a quarter of an hour he brought at least a dozen good specimens in the
-bottle he had borrowed.
-
-It was natural to inquire to what his success was due. He told me that
-it was his first attempt at collecting, but that just before joining
-me he had noticed the ends of the breathing-tubes sticking out of the
-water. This excited his curiosity, and on moving the mud with his
-walking-stick, the insects were seen to crawl away slowly. When he
-saw me transfer the Water Scorpion from the net-tube to the bottle, he
-immediately recognized it. Then he courteously offered his help, for
-which, of course, I was grateful.
-
-We may keep the Water Scorpion alive for a considerable time in a small
-bottle of water, in which is some growing weed. If we watch it moving
-about, we shall see that the front legs are used for locomotion as well
-as for seizing prey. Some authors doubt this. Any one may settle the
-question for himself, if he will put one of these insects into a small
-bottle with plenty of weed. Generally, however, the insect uses only
-the second and third pairs for walking, the first pair being raised and
-directed forward, with the tarsus bent at an angle (Fig. 42). Even when
-it does use its front legs for locomotion, the action is not that of
-walking; the insect employs these limbs to pull itself along in a sort
-of ‘hand-over-hand’ fashion, but on a level surface it uses the first
-pair in the same way as it does the other two pairs.
-
-Its habit of burying itself in the mud may also be watched with very
-little trouble. A common pudding-basin will make an excellent aquarium
-for this purpose. The bottom is to be covered with garden mould and
-vegetable _débris_, mixed with a few stones. The whole mass should
-be arranged unevenly, so that when water is added it may not form one
-sheet, but a series of small shallow pools. Very little duckweed will
-serve to keep it sweet. It only remains to drop in the Water Scorpion.
-Before long it will accommodate itself to its new surroundings, and so
-bury itself that it will be no easy task to discover it.
-
-An aquarium of the kind described stands at present on my
-writing-table. Many have been the inquiries as to what kind of creature
-lived therein; and more than one old hand at collecting has failed to
-find the insect. It is always safe to look round the sides of the basin
-for the breathing-tube; if it is not detected in this situation, a
-glance along the surface of the tiny pools will probably show a break
-in the film. The Water Scorpion will not be far off.
-
-That the insect really does cover itself with mud may be demonstrated
-by transferring it from the aquarium described to any shallow vessel,
-and allowing a fine stream of water--say, from a dipping-tube--to fall
-gently on it. The mud will be washed away, and in a few seconds will
-settle at the bottom.
-
-It is well to keep such an aquarium covered, for the Water Scorpion has
-no mean power of flight. A circular plate of glass, which may be bought
-for a few pence, makes the best cover, but a piece of fine muslin
-fastened round the rim of the basin will do. Swammerdam says, ‘These
-Water Scorpions live all the day in the water, out of which they rise
-about the dusk of evening into the air, and so flying from place to
-place, often betake themselves in quest of food to other waters.’ Then
-follows a deduction which shows how far he was in advance of his time:
-‘This affords us a satisfactory reason for the great number of insects
-that immediately appear in the smallest collections of water, since
-they may very well get thither when it is dark, so that the opinion
-which ascribes to putrefaction the power of forming insects, &c., must,
-by this instance of the Water Scorpion’s nocturnal transmigrations,
-appear more and more frivolous and unnecessary.’
-
-  [Illustration:
-
-   FIG. 43.--_A._ Water Scorpion. _a_, rostrum;
-   _b_, wing-cases; _c_, wings; _d_ _d_,
-   second and third pairs of legs; _e_, raptorial legs (the
-   first pair); _f_, spine forming breathing-tube; _g_,
-   parasitic mite. _B._ Portion of an oviduct containing eggs
-   (magnified). _C._ An egg (magnified). _D._ Parasitic
-   mite. _a_, head; _b_, eyes; _c_, legs; _d_
-   _d_, legs (seen from under surface). (After Swammerdam.)]
-
-No larva or other animal that is of any value should be kept in the
-same aquarium with the Water Scorpion. Dr. Hill, who annotated the
-English edition of Swammerdam, says, ‘There is not perhaps in all the
-animal creation so outrageous or fierce a creature against those weaker
-than itself as the Water Scorpion. It destroys, like the wolf among
-sheep, twenty times as many as its hunger requires.’ The Rev. G. C.
-Bateman placed one in a saucer with a tiny minnow; ‘but no sooner did
-the little fish swim within reach of the fore-legs of the scorpion
-than it was seized by them, and pressed against the hungry creature’s
-rostrum.’ It seems to be particularly fond of Asellus, the water
-woodlouse. I have often taken dead specimens of this crustacean, sucked
-completely dry, from between the raptorial legs of the insect. One
-specimen was so thoroughly cleaned out that it was mounted just as it
-was, the only preparation being a brief soaking in spirit.
-
-In examining the head the eyes may be readily distinguished, and on
-pressing the rostrum or beak with a needle, the proboscis will be
-forced out, just as one may force out the sting by pressing the abdomen
-of a bee or a wasp. In this group the antennae are three-jointed and
-concealed. When one begins to look for these organs he will probably
-come to the conclusion that the concealment is highly effectual.
-
-A very simple method of finding them in a spirit specimen is to take
-the insect between the thumb and index finger of the left hand, holding
-it up to the light in such fashion as to keep the first pair of legs
-well clear of the head. Then, with a needle held in the right hand,
-raise the thorax till it lies in the same plane as the body. Each
-antenna lies in a groove beneath the eye. Gentle manipulation with the
-needle will lift them out, so that they may be clearly seen, not only
-with the hand magnifier, but with the unassisted eye. Or the insect may
-be pinned down under water instead of being held in the hand, and the
-antennae lifted or brushed out of the groove.
-
-It will greatly simplify matters if, before attempting to raise the
-wings, the fact is borne in mind that the tip of the right wing-case
-lies over that of the left. It is perhaps as well to remove the
-wing-case altogether by inserting a needle under it, and gently raising
-it, using a little pressure in an outward direction. It will then be
-quite time to raise the wing and to see the method of folding and
-unfolding.
-
-  [Illustration: FIG. 44.--Raptorial leg of Water
-  Scorpion.]
-
-In Fig. 44 we have a representation of the raptorial (front) leg
-of this insect. This leg should be compared with the legs of other
-Insects--not in pictures only, but in actual specimens--that we may see
-how, while the general plan is preserved, different joints are modified
-to suit the special function of this limb--that of taking prey. (See
-also Fig. 43.)
-
-The thigh (_f_) is the largest joint, for the obvious reason that
-it contains the muscles that work the tibia and tarsus, which together
-form a kind of knife-blade, shutting down into a groove in the thigh,
-which may very well be compared to the handle of a pocket-knife. This
-description, however, is not to be taken on trust. It is not enough
-to read about the groove: we must see it for ourselves, raise the
-‘knife-blade’ from the groove, and press it down again, and pass the
-needle along the groove. If we examine the interior of the groove, we
-shall find that there is a projection along the bottom, so that a cross
-section would appear like this--W[image]. The inner portion of the
-tibia is also grooved; so that when once the prey is seized by this
-powerful limb, it has no chance of escape. The tarsus (_tar_)
-is not clearly distinguished from the tibia (_tib_) in the
-engraving, but it may be distinctly seen as a claw-like appendage in a
-living or dead specimen.
-
-The breathing-tube remains to be examined. It may be detached from the
-body for more convenient manipulation. When this is done, the tube will
-be seen to consist of two pieces, each grooved on the inner side and
-set with hairs, which, as they interlock, prevent the entrance of water.
-
-A somewhat similar arrangement occurs in the proboscis or tongue of
-butterflies. There is perhaps a closer parallel in the antennae of
-the masked crab, which, under certain conditions, form a kind of
-breathing-tube, each antenna being joined to its fellow by the hairs
-with which it is set.
-
-There are two other Water Bugs which lend themselves to our purpose
-very well. Each is popularly called Water Boatman, though that name is
-better confined to Notonecta, because the insects of this genus ‘row
-themselves about on their backs with their long feathered legs.’ In the
-United States they are called Water Cicadae, from the shrill noise they
-make, probably by rubbing the fore-legs together.
-
-  [Illustration: FIG. 45.--Water Boatman.]
-
-In Fig. 45 the Water Boatman (_Notonec´ta glauca_) is represented
-as seen from above--a position in which we shall rarely discover it,
-if we keep it in a small aquarium. In Fig. 46 the same insect is shown
-swimming on its back, or in the position it assumes when taking in a
-supply of air. The end of the abdomen and the tips of the feet rest
-against the surface-film; and at the slightest alarm a vigorous stroke
-of the last pair of legs sends the insect to a place of safety. From
-the way in which these insects habitually swim, Mouffet came to the
-conclusion that it was probable men learned the art of swimming on
-their backs from them.
-
-  [Illustration: FIG. 46.--Water Boatman swimming.]
-
-Active as the Water Boatman is, it often falls a victim to the Water
-Scorpion, if both are kept in the same aquarium. I learnt this fact by
-experience, for having put two Water Boatmen into a small tank in which
-was a Water Scorpion, I found both the former dead in the morning. It
-was evident that their destroyer had had a good meal.
-
-The only point to which attention need be called in examining the Water
-Boatman is its method of taking in a supply of air. In looking at a
-dead specimen we shall see a ridge or keel running down the middle of
-the under side of the abdomen, and fringed with hair on each side.
-A similar fringe runs along each side of the abdomen, thus forming
-two passages along which the air taken in at the end of the body is
-conveyed to the spiracles, the largest of which are on the thorax.
-
-Corixa (Fig. 47) swims with its back uppermost, and when kept in the
-aquarium may generally be seen foraging for small creatures--larvae or
-worms--among the sediment at the bottom. Bateman, who kept a number
-of these insects, says that he fed his specimens on garden worms and
-pieces of raw meat. Mine have always foraged for themselves, and done
-very well without feeding. They may often be seen to rub the short
-fore-legs alternately across the front of the head, probably for the
-purpose of producing a call-note. I have often watched them at this
-practice, but have never been able to detect any sound. The defect is
-evidently in my sense of hearing, for the sounds rest on undoubted
-authority, and are coincident with the rubbing of the fore-legs across
-the head.
-
-  [Illustration: FIG. 47.--Corixa, with wings expanded.]
-
-Where sound-producing organs exist it is more than probable the
-capacity for receiving sound-impressions also exists. Graber made some
-interesting experiments to test the sense of hearing in Corixa. His
-results are thus summarized by Sir John Lubbock[28]: ‘He placed some
-Water Boatmen (Corixa) in a deep jar full of water, at the bottom
-of which was a layer of mud. He dropped a stone on the mud, but the
-insects, which were reposing quietly on some weeds, took no notice. He
-then put a piece of glass on the mud, and dropped the stone on to it,
-thus making a noise, though the disturbance of the water was the same.
-The Water Boatmen, however, at once took to flight.’
-
-
-
-
-                              CHAPTER IV
-
-                     SPIDERS, MITES, AND MYRIAPODS
-
-
-In this chapter we shall take examples from two Classes--the
-Arachnoi´dea and the Myriap´oda. To the first-named Class belong also
-the Scorpions, which, with the Book Scorpions, the Harvestmen, and some
-others, may be neglected here. This will leave us only the Spiders and
-Mites to deal with.
-
-Every one knows a Spider when he sees one, though not every one can
-give offhand a definition that shall include the whole Order. Let us
-endeavour to express their characters in simple terms, keeping in mind
-the definition of head, thorax, and abdomen in Chapter II. In Spiders
-the head and thorax are joined together in one unsegmented portion,
-called the cephalothorax, and this is connected with the abdomen, which
-is also unsegmented, by a more or less slender stalk or peduncle. So
-that while Insects have three regions, Spiders have but two. We may
-express the difference thus:
-
-    Insects      head, thorax      abdomen.
-                  \---v---/[image]
-    Spider      cephalothorax      abdomen.
-
-The cephalothorax bears six pairs of appendages (Fig. 48A).
-Taking these in order, there are--
-
-   1. A pair of falces (_an_), representing the antennae of
-   insects. These have a movable claw-like joint at the extremity,
-   perforated so as to convey into a wound the secretion from the
-   poison-glands.
-
-   2. A pair of five-jointed pedipalps (_p_), sometimes called
-   maxillary palpi, from the fact that the parts whence they spring
-   correspond to the maxillae of insects (Fig. 21A,
-   _d_). In the female the last joint terminates in a claw; in
-   the male this joint is specially modified for sexual purposes
-   (Fig. 48B).
-
-   3. Four pairs of walking legs, of which only the coxae
-   (_c_) are shown in the diagram. The two front legs are
-   often used as organs of touch.
-
-Breathing is carried on by chambered air-tubes or lung-sacs, and in all
-our British Spiders (with the single exception of the native Trap-door
-Spider, which, by the way, does not make a trap-door) there are also
-air-tubes resembling those of Insects. The lung-sacs open to the
-external air by stigmata (_st_) on the abdomen, while the ordinary
-air-tubes open near the spinnerets (_sp_), the organs employed in
-the production of the silky threads from which are formed webs, nests,
-egg-bags, and ropes. By means of these threads, spiders drop from their
-webs to the ground, construct flying bridges from one point to another,
-and even in some sort travel through the air.
-
-Spiders live upon the juices of their prey, which are drawn up into the
-stomach by means of a suctorial apparatus at the end of the gullet.
-The young, when they leave the egg, resemble their parents in all
-respects but size--that is, they undergo no metamorphosis.
-
-The eyes of spiders are simple, and six or eight in number. These vary
-much in size and relative position, and furnish characters of great
-importance in classifying species. Those of the Hunting Spiders, which
-make no web, but pursue or spring upon their prey, are usually arranged
-in three rows; while those which make webs for the capture of prey have
-the eyes in a double row. In all cases they are on the front part of
-the upper surface of the cephalothorax.
-
-  [Illustration:
-
-   FIG. 48.--_A._ Scheme of under surface of Wolf
-   Spider (female). _B._ Pedipalp of male (enlarged). For
-   other references, see text.]
-
-The Common Garden Spider (_Epei´ra diade´ma_) is a very good
-subject, and there can be no difficulty in procuring any number of
-specimens. The smallest garden will be sure to yield a plentiful
-supply; and even if we have no garden, a very superficial search
-among the hedgerows will give us as many as we can possibly want.
-Every one knows this spider, and the beautifully regular web which
-it makes. First of all, what one may call the outline of the web
-is spun--strong threads stretching from point to point, to which
-are attached lines radiating from a common centre. This may be
-represented diagrammatically by drawing a circle and producing radii
-from the centre to the circumference in all directions, or by making a
-rectangular figure and drawing lines to the boundaries from the point
-where the diagonals intersect. It must not, however, be supposed that
-the outline of the web is of a regular form. In this respect the spider
-adapts itself to circumstances, and spins a greater or less number of
-supporting threads, as may be necessary.
-
-  [Illustration: FIG. 49.--Garden Spider and Web.]
-
-Then the spiral is made (Fig. 49) from the centre to the circumference.
-The first few turns are of the same character as the radial lines; but
-all the rest of the short lines forming the spiral, and connecting
-the radial lines, are coated with a viscid secretion, which is the
-essential part of the snare; for the victims are really limed like
-birds on a twig, not entangled in the threads. It is well to test the
-character of the different parts of the spiral, not only by touch,
-which is convincing enough, but with pocket lens. Our low powers will
-not give such results as are shown in Fig. 50, but we shall have no
-difficulty in distinguishing the sticky parts from those not coated
-with the secretion.
-
-  [Illustration: FIG. 50.--_A_ Adhesive Threads of
-  Spiral. _B._ Non-adhesive Radial Threads.]
-
-It may be doubted whether all the Spiders of this genus make the
-spiral in the same way, for observers differ in their description of
-what they have seen. Some say that a non-adhesive spiral from centre
-to circumference is first made, and that the spider then moves ‘in a
-closer spiral from the circumference inwards, biting away the former
-spiral, replacing it by another, which is viscid and adhesive[29].’ Dr.
-Butler, on the other hand, who ‘watched spiders for months together,
-petting, feeding, and trying experiments with them every morning,’
-after describing the making of the first and non-adhesive part of the
-spiral, says, ‘This line is not carried to the boundary, but at some
-distance from the centre a second is commenced, formed of extremely
-viscid silk, upon which the gummy secretion is distinctly visible,
-with the aid of a lens, in the form of closely approximated globules
-of amber-coloured glue. It is said that when the viscid lines are
-completed the spider cuts away the unadhesive lines, but this I have
-never observed[30].’ My own observations lead me to believe that Dr.
-Butler is correct in his description. Though I have often watched,
-I have never seen a spider ‘biting’ away any part of its web, nor
-would the falces appear to be adapted for such an operation. They are
-piercing, not cutting, weapons.
-
-The spider may be watched at leisure, if put into a bottle of moderate
-size, the top of which should be covered with muslin or calico to
-prevent escape. Here it is fairly easy to bring the pocket lens into
-play, and to distinguish the different parts of the animal. The eyes,
-and their arrangement, should be particularly noticed.
-
-  [Illustration: FIG. 51.--Anchorage of Web.]
-
-Blackwall, in support of the position that in making their webs
-spiders are guided by touch rather than sight, says, ‘Various species,
-when confined in spacious glass jars placed in situations absolutely
-impervious to light, construct nets which do not exhibit the slightest
-irregularity of plan or defect of structure[31].’ My specimens have
-always been kept in the light, and in small bottles rather than
-spacious jars, but I have never seen spiders attempt to make a
-geometrical web under such conditions.
-
-A bottle which for some months served as a prison-house for a Garden
-Spider now stands on my writing-table. Its sides are marked by hundreds
-of ‘anchorages’--but the threads cross and recross, forming in some
-parts a kind of sheet, and in others a tangled mass. Some of these
-threads must have been covered with viscid secretion, for flies were
-limed, and so fell a prey to the spider. Their dried skins are dotted
-about among the threads, and the spider itself perished long ago from
-cold. But I keep the bottle as a curiosity, to show that these spiders
-do not always make geometrical webs.
-
-When one has a Garden Spider in a bottle, it may be observed to
-practise a curious and very effective method of disabling its prey.
-If a bluebottle or any other large fly be dropped and entangled among
-the threads, the spider will envelop it in a sheet of web. This is
-how Blackwall describes the operation: ‘Causing the victim to rotate
-by the action of the third pair of legs and the palps, the first pair
-of legs also being frequently employed in a similar manner, they
-extend the spinners laterally, and applying to them alternately the
-_sustentaculum_ of each posterior leg, they seize and draw out
-numerous fine lines in the form of a fillet, which they attach to their
-revolving prey, and thus involve it in a dense covering of silk from
-one extremity to the other. By means of this stratagem they are capable
-of overcoming formidable and powerful insects, such as wasps, bees, and
-even large beetles[32].’
-
-The operation does not occupy much time; in a very few minutes the fly
-is swathed in a silky covering as completely as an Egyptian mummy in
-its linen folds. Of course resistance, much less attack, is out of the
-question, and when it is thus rendered powerless for harm the spider
-proceeds with its meal.
-
-The _sustentac´ulum_--or support--is a strong movable spine near
-the end of the tarsus, on the under side of each of the last pair of
-legs. These spines act in opposition to the claws, and thus these
-animals are enabled to hold with a firm grasp such lines as they have
-occasion to draw from their spinners with the feet of the hind legs,
-and such also as they design to attach themselves to.
-
-With regard to this method of swathing prey, Hudson[33] says of
-an Argentine spider, ‘that its intelligence has supplemented this
-instinctive procedure with a very curious and unique habit. The
-Pholcus, in spite of its size, is a weak creature, possessing
-little venom to dispatch its prey with, so that it makes a long and
-laborious task of killing a fly. A fly, when caught in a web, is a
-noisy creature, and it thus happens that when the Daddy longlegs--as
-Anglo-Argentines have dubbed this species--succeeds in snaring a
-captive, the shrill outrageous cries of the victim are heard for a
-long time--often for ten or twelve minutes. This noise greatly excites
-other spiders in the vicinity, and presently they are seen quitting
-their webs and hurrying to the scene of conflict. Sometimes the captor
-is driven off, and then the strongest or most daring spider carries
-away the fly. But where a large colony are allowed to continue for a
-long time in undisturbed possession of a ceiling, when one has caught
-a fly he proceeds rapidly to throw a covering of web over it, then,
-cutting it away, drops it down and lets it hang suspended by a line at
-a distance of two or three feet from the ceiling. The other spiders
-arrive on the scene, and after a short investigation retreat to their
-own webs, and when the coast is clear our spider proceeds to draw up
-the captive fly, which is by this time exhausted with its struggles.’
-
-In this connexion Hudson notes that spiders are attracted by the sound
-of the vibration of a string or wire, thinking it made by an insect
-that has been caught; and he says that the stories of tame spiders
-are founded on a misunderstanding of the motive that brings the
-animal down. We may well doubt if spiders are attracted by music, but
-that some spiders possess a sense of hearing, or something analogous
-thereto, seems to be proved by the existence of stridulating organs in
-certain members of the group.
-
-  [Illustration: FIG. 52.--Foot of Garden Spider.]
-
-  [Illustration: FIG. 53.--Spinnerets of Garden Spider.]
-
-Two other points remain to be noted. The feet should be examined,
-for their structure throws some light on the way in which the Garden
-Spider runs so securely to and fro on the radial lines. One of the
-legs of a dead specimen should be detached, and its armature of spines
-and hairs noted. The foot is armed with three stout claws, which
-are pectinated--that is, toothed like a comb, and beneath them are
-smaller ones, sometimes described as toothed hairs. It will be easy
-to understand what a secure foothold these claws give the animal as it
-runs backwards and forwards over the radial lines; for if the web be
-shaken by the wind or designedly its owner can take a firm hold with
-each foot, and thus have eight separate points of attachment. An inch
-hand lens is quite sufficient to give a general idea of the hairy and
-spinous clothing of the legs and the position of the claws; but to see
-the teeth a higher power--a half-inch--will be necessary.
-
-It is a good plan to choose a freshly killed specimen for the
-examination of its spinnerets. If the spider is laid on its back in a
-glass dish, gentle pressure on the abdomen away from the cephalothorax
-will cause the material secreted by the spinning-glands to ooze out.
-This, however, cannot be done if the specimen has been for some time
-in spirit. We shall be able to make out six tubes (four of them larger
-than the other two) grouped round the anal aperture; but, for the
-present, we must take for granted the fact that these are made up of
-a number of smaller tubes, so that the end of each spinneret is not
-unlike the rose of a watering-can. A good half-inch will give some
-indications of this rose-like appearance.
-
-The Jumping Spider (_Sal´ticus sce´nicus_) belongs to a family
-the members of which make no web or snare for the capture of prey, but
-trust for their food-supply to their skill in stalking flies and other
-insects, which they capture by a sudden spring. It is from this habit
-that the type-genus and the family have received their scientific and
-popular names.
-
-The common British species is extremely abundant, and wherever flies
-are plentiful these spiders will not be very far off. This is the case
-not only in the country, but also in London and other large towns. It
-is a noticeable spider from its coloration--black marked with white.
-The eyes are eight in number; though the artist in our illustration
-has only represented four. The centre two of the front are the largest
-of all, and have been compared not inaptly to bull’s eyes. Two others
-are placed on each side of the cephalothorax, so that the eyes form,
-roughly, three sides of a square, and the central eyes in the lateral
-lines are the smallest. We may represent them thus [image], while the
-eyes of the Garden Spider are disposed in this fashion [image].
-
-  [Illustration: FIG. 54.--Jumping Spider. (Line shows
-  natural size.)]
-
-  [Illustration: FIG. 55.--Falces of Male Jumping Spider.]
-
-It requires some little practice to detect the eyes of spiders and to
-remember their position in the different genera, but by examining every
-spider met with, and consulting some handbook to the group, one will
-soon be able to determine the commoner British species.
-
-With a couple of needles we may remove the falces (Fig. 55) for
-examination; and there is no difficulty in mounting them, as shown in
-the cut, on a piece of card, so that they may be compared with the same
-weapons in other species. For example, the falces of the Garden Spider
-differ from those of the Jumping Spider in that they are short and
-stout, and the teeth on the basal joint are more in number.
-
-The following account of the habit of this spider in capturing prey is
-from Kirby and Spence’s _Introduction to Entomology_ (ed. 1870, p.
-453):--‘When these insects spy a small gnat or fly upon a wall, they
-creep very gently towards it with short steps, till they come within a
-convenient distance, when they spring upon it suddenly like a tiger.
-Bartram observed one of these spiders that jumped two feet upon a
-humble-bee. The most amusing account, however, of the motions of these
-animals is given by the celebrated Evelyn in his _Travels_. When
-at Rome, he often observed a spider of this kind hunting the flies
-which alighted upon a rail on which was its station. It kept crawling
-under the rail till it arrived at the part opposite to the fly, when
-stealing up it would attempt to leap upon it. If it discovered that
-it was not perfectly opposite, it would immediately slide down again
-unobserved, and at the next attempt would come directly upon the
-fly’s back. Did the fly happen not to be within a leap, it would move
-towards it so softly, that its motion seemed not more perceptible
-than that of the shadow of the gnomon of a dial. If the intended prey
-moved, the spider would keep pace with it as exactly as if they were
-actuated by one spirit, moving backwards, forwards, or on each side
-without turning. When the fly took wing, and pitched itself behind the
-huntress, she turned round with the swiftness of thought, and always
-kept her head towards it, though to all appearance as immovable as one
-of the nails driven into the wood on which was her station: till at
-last, being arrived within due distance, swift as lightning she made
-the fatal leap and secured her prey.’
-
-This spider employs a clever precaution against falling, when about to
-spring upon its prey. It applies the end of the abdomen to the surface
-on which it stands, and opening its spinnerets, makes an ‘anchorage’
-(Fig. 56). Then, by the act of springing, it draws from the spinnerets
-a line attached to the spot from which it started. This line is strong
-enough to support the spider in case it misses its prey.
-
-  [Illustration:
-
-   FIG. 56.--_A._ Foot or Jumping Spider. _B._
-   Scopula. (Much enlarged.)]
-
-The foot of the Jumping Spider is extremely interesting, and shows
-a very ingenious arrangement, by means of which the animal can run
-with difficulty on smooth polished upright surfaces, or retain its
-footing when it alights on such surfaces after a spring. We can see
-this arrangement in Fig. 56. Just behind the claws is a bundle of
-coarse hairs, technically called a _scop´ula_, or little brush.
-From these hairs adhesive matter flows, and in this fashion the spider
-literally sticks on. With this brush of hairs may be compared the
-tarsal cushions of many flies, and the adhesive hairs of Dytiscus
-and other beetles (see Chap. II)--though these last have a different
-function.
-
-Diving Spiders (_Argyrone´ta aquat´ica_) are especially suitable
-for our purpose. They are very common in most ponds, and in some
-places are so abundant as to be almost a nuisance to the collector who
-is in search of other things. Three of them are represented in Fig. 57.
-One is swimming; another is just entering the bell-shaped web under
-water; and the third is just climbing out of the water on to the broad
-floating leaves of the water crowfoot.
-
-  [Illustration: FIG. 57.--Diving Spiders.]
-
-De Geer’s account of these spiders is extremely interesting[34], and
-we may verify it for ourselves, for these creatures may be kept without
-any trouble. They certainly agree, when a number are kept in captivity,
-much better than do other spiders. De Geer kept several in the same
-aquarium, and says that when they met they felt each other with their
-palps, and opened their falces, but he never saw them do any harm to
-each other. I have kept them under similar conditions with the same
-result.
-
-He tells us that these spiders spin under water a cell of strong,
-close, white silk, the shape of which he compares to a skull-cap, the
-half of a pigeon’s egg, or a diving-bell. In September, 1736, he first
-became acquainted with these creatures, and kept one in an aquarium for
-four months. It made its cell against the side of the aquarium, and the
-top of it rose above the surface of the water. (This was due to its
-being inflated. The web was not spun above the surface.) The walls of
-the cell were very thin, but it was filled with air, and the spider was
-resting inside, head uppermost, with its legs pressed against the body.
-
-About three months later he found that the mouth of the cell was
-closed, and the spider was comfortably settled in its winter quarters.
-When pressure was applied the cell burst and the air escaped, mounting
-up to the top in bubbles. The spider made its way out, and took an
-Asellus that was offered, and made a meal of it.
-
-De Geer then came to the conclusion that these cells under water were
-constructed for the purpose of affording the spider a retreat when the
-water was frozen over, so that they could not come to the surface
-for a supply of air. He found, however, by observation, that they
-were also made in summer by both sexes. In a cell of this kind the
-female deposits her eggs--from eighty to a hundred in number, enclosed
-in a cocoon of white silk--and keeps guard over them, with her head
-defending the entrance to the cell.
-
-He succeeded in finding out the method by which the Diving Spider fills
-its cell with air. He noticed that when the creature was moving about
-in the water, its body was covered with a layer of air, and that this
-air was renewed from time to time when the animal came to the surface
-and raised its abdomen above the water. Loaded, so to speak, with air
-in this fashion, the spider descended, and entered the cell backwards,
-leaving an air-bubble. Having repeated this several times, at last she
-removed all the water from the cell, introducing in its place an equal
-quantity of air.
-
-It is very easy to watch the Diving Spider making its dwelling under
-water, and filling it with air. First of all the web is woven in a
-bell or thimble shape between the sprays of water-weed, or against the
-bottom or side of the aquarium. It is curious to notice how practices
-that must be necessary when the creature is at liberty are continued
-in captivity where they are useless. A web constructed in running
-water, or even in a pond or ditch, is liable to be swept away or to be
-emptied of air by a very slight current, so its owner has recourse to
-a system of guys and supporting threads, which are not required when
-the spider is safely housed in a small aquarium. Nevertheless, the guys
-are made. In an eight-ounce bottle I have now a male Diving Spider,
-which has lived there for about seven months. Its cell is made between
-the whorls of a spray of milfoil, and guy threads have been carried to
-no less than five whorls--two above and three below the opening. Now
-that it is filled with air, the cell gleams in the water like a great
-bubble of quicksilver. The air may be expelled by shaking or tilting
-the bottle, and if the web be not damaged the spider will generally
-refill it with air, though sometimes it prefers to make a new dwelling.
-Fig. 58 shows the cell of a Diving Spider; the white lines represent
-supporting threads attached to the water plants.
-
-In examining dead specimens we shall find that, contrary to what is
-usual, the male exceeds the female in size. I have a slide of a male,
-with the legs spread out before and behind, and the measurement from
-the claws of the first pair of legs to those of the fourth pair is 1¾
-inches. The body is ¾ inch long. The whole surface is more thickly
-clothed with hair than is the case with other spiders, and the reason
-for this is obvious. This hairy body-covering serves to carry down into
-the water a layer of air, and the fringe of hair on the legs makes them
-efficient swimming organs.
-
-  [Illustration: FIG. 58.--Cell of Diving Spider.]
-
-The Order of Mites will yield us subjects for our pocket lens. Mites
-are related to Spiders, but form a distinct Order. Like the Spiders,
-some are aquatic, though the most of them live on land. Many are
-parasitic, during the whole or part of their lives subsisting on
-the juices of their hosts: the food of others consists of organic
-_débris_, and these seem to be of benefit to man, since they act
-as scavengers. If we turn to page 96 we shall there find noted the
-points of difference in the arrangement of the main divisions of the
-body in Insects and in Spiders. In Mites the distinction between the
-cephalothorax and abdomen is lost, and the body is more or less oval or
-globular. In the perfect forms there are eight legs; but some, in their
-earlier stages, have only six. The mouth may be adapted for biting,
-though it is usually suctorial. In the Cheese Mites and some others
-breathing seems to be carried on through the skin, for there are no
-air-tubes; but in most Mites air-tubes, with two stigmata, are present.
-
-If we take a dip with the collecting-net in almost any pond we shall
-be pretty sure to capture some specimens of Water Mites of the genus
-Hydrach´na, easily recognizable by their bright coloration, their eight
-swimming legs thickly fringed with hair, and their unceasing activity.
-They may be kept in a bottle, or other small vessel, with some
-water-weed, and will forage for themselves. In Fig. 59 we shall see
-the points we have to look for in examining a Water Mite with a pocket
-lens. There should be no difficulty in making out in the specimen all
-the details shown in the cut.
-
-It may be that they will breed: if so we should avail ourselves of
-the opportunity of watching their development. Their life-history is
-somewhat curious, and is specially interesting from the fact that
-while Swammerdam had some faint perception of the true meaning of what
-he saw, De Geer, writing a hundred years later, drew entirely wrong
-conclusions from similar observations. It was left for Dugès to clear
-up the matter in the _Annales des Sciences Naturelles_, 1834.
-Before summarizing the account of the French naturalist it may be well
-to quote what Swammerdam and De Geer have said on the subject:--
-
-‘There is nothing more remarkable in this insect [the Water Scorpion]
-than that it constantly appears covered with a prodigious number of
-nits of different sorts and sizes, though perhaps we may with more
-reason consider them as so many little creatures, which live and grow
-by sucking the Scorpion’s blood. These are somewhat of an oblong
-figure, approaching to round, and have a shining, and as it were
-bloated, surface, without any of the rings observable in most insects.
-The neck is oblong and shaped like a pear, with the small end sticking
-in the Scorpion’s body. The colour of this insect is a mean between
-that of vermilion and purple; and when it is pretty well grown there
-appears within it an elegant transparent spot or particle (Fig. 59).
-
-  [Illustration: FIG. 59.--Red Water Mite (nat. size, and
-  under surface magnified).]
-
-‘This spot or particle induced me to consider with more attention
-this minute and hitherto unregarded insect, and even to undertake the
-dissection of it. But who would imagine that on this examination it
-should prove a perfect and surprising insect? This is, however, a
-certain fact; and thus in that infinite variety of works, by means of
-which God is pleased to make Himself known to us, we ever meet with new
-matter of admiration and astonishment.
-
-‘This little creature being extracted from the shell that covered it,
-looks like a young spider before it has left its egg. On the fore part
-is the head (Fig. 43D, _a_) and on its head are the eyes, _b_: under
-the eyes are placed its little legs elegantly coiled and folded, _c_
-_c_; but they appear much more distinctly on turning the insect on its
-back, _d_ _d_; and in this situation also it best appears with what art
-these legs are laid up in the shell, and all are covered with hair.
-The colour of this little creature is, as I have already observed, a
-mean between that of vermilion and purple; and this colour shows itself
-through the coat or shell, which is transparent. I cannot determine to
-what species of insects this is to be referred; nor can I say to what
-size it grows, or by what kind of creature it is thus deposited on the
-Water Scorpion in the form of an egg, there to receive life and growth.
-Nevertheless, I cannot but look on the discovery I have made as very
-interesting, since it proves that there are in the nature of things
-eggs which acquire a sensible growth by an entraneous nourishment,
-unless perhaps some naturalist should choose to consider this as a
-complete insect, rather than as an egg; nor shall I strenuously oppose
-his opinion, seeing that, in all cases, the egg is in reality no
-other than the insect itself, which remains in that state till it has
-acquired sufficient strength to break its prison, and live without such
-a covering[35].’
-
-Having quoted Swammerdam, let us see what De Geer has to say on the
-subject:--
-
-‘On the body and legs of many aquatic insects, such as Dytiscus and
-Water Scorpions, may be frequently seen little oval, seed-like bodies,
-of a bright red colour, firmly attached, and, as it were, implanted
-in the skin, by a little stalk. I have had Water Scorpions with the
-upper surface so covered with these red bodies that there was scarcely
-a vacant space on the skin. They are most frequently to be seen in
-the spring; but the insects on which there was such a great number
-did not live long with me. Having crushed some of these seed-like
-bodies, I found them filled with red liquid matter. I am convinced, by
-experiment, that they are the eggs of Water Mites, since there came out
-of them little red Mites with round bodies and long legs, which swam
-about with great swiftness.
-
-‘These red Water Mites, then, attach their eggs to the bodies and legs
-of larger aquatic insects, and there they remain till the young are
-hatched. And since we find eggs of many different sizes, we may be
-sure that they grow and increase in size, doubtless owing to a certain
-nutritive juice which passes from the body of the insect into the egg.
-Hence it is, as I have seen myself, that Water Scorpions loaded with
-these eggs become weak and feeble, because they are obliged to furnish
-their hangers-on with nourishment from their own bodies. Moreover,
-these eggs appear to cause the Water Scorpions some irritation or
-uneasiness, since I have often seen them rub with their feet those
-parts of the body where the eggs were; and perhaps they did this with
-the view of rubbing them off, but they were too securely fastened[36].’
-
-Dugès watched the development of the common Red Water Mite (Fig. 59),
-and tells us that towards the end of May the females deposit their eggs
-in the leaves of pondweed, which they puncture with their beaks. The
-larva (Fig. 60), red in colour, with six legs, is free-swimming, and
-has a large beak, which looks like a great head, and terminates in a
-narrow mouth. It is not known how long this larval stage continues;
-but in the next stage (Fig. 61) the Mite becomes parasitic on aquatic
-beetles and bugs, fastening its beak into the body of its host,
-from which it derives its nourishment. The legs and palps are often
-retracted or absorbed, so that it is not difficult to understand
-how it was Swammerdam and De Geer took these parasitic nymphs to
-be the eggs of the Mite. During their parasitic condition they
-increase considerably in size, at last emerging as adult eight-legged
-free-swimming Mites. It was just before the emergence of the Mite
-that Swammerdam examined the parasitic nymph, for he figures the
-‘insect,’ which he extracted from the egg, as having eight legs (Fig.
-43D).
-
-  [Illustration: FIG. 60.--Larva of Water Mite.]
-
-  [Illustration: FIG. 61.--Nymph of Water Mite.]
-
-I once found a Water Mite in the body of a Dytiscus[37]. I was
-breaking up the beetle, and had removed the elytra and the wings. I
-only wanted the external skeleton; so a slit was made between the
-plates of the dorsal and ventral surface, and the intestines removed.
-The Mite was embedded in the fat-body. I could find no mention in the
-literature of Beetles or Mites of any similar occurrence; and should
-scarcely have mentioned it here, had I not been unexpectedly confirmed
-by my friend Mr. G. E. Mainland, F.R.M.S., who once had a similar
-experience, and who kindly allows me to quote from a letter he sent me
-on the subject:--
-
-‘I am sorry to say I can find no documentary evidence as to the
-Arachnid I found embedded in the tissues of Dytiscus, but a good deal
-has come back to my recollection. On removing the right elytron and
-slitting up the dorsal surface, I found it in the tissue close up to
-the thorax. I cannot recollect what ultimately became of it, after I
-had shown it to friends at the Hackney Microscopical Society.... I know
-that I carefully measured the Hydrachna (which was abnormally large)
-and its relative size to that of its host, and made a comparison in a
-lecture (to the Senior Band of Hope at St. Michael’s, Hackney) of a man
-with a creature as large as a guinea-pig under his shoulder-blade.’
-
-The occurrence of the Mite _inside_ the Beetle was, of course,
-quite exceptional. It probably found its way in through one of the
-abdominal spiracles.
-
-The Beetle Mite (_Gam´asus coleoptrato´rum_) (Fig. 62) is
-extremely common, and is parasitic on the Dung Beetle and on the Humble
-Bee, so that in order to examine the parasite we must capture the host.
-There can be no difficulty about this, for Dung Beetles and Humble Bees
-are plentiful enough. This Beetle Mite, apparently, does not infest
-other species of beetles. I have kept the Devil’s Coach Horse in a
-bottle with the common Dung Beetle for some months, and though the
-latter swarmed with these parasites, they never left their host for
-the other beetle. Even when removed by means of a small brush from one
-beetle to the other, they left the Devil’s Coach Horse of their own
-accord, and soon made their way back to the Dung Beetle.
-
-  [Illustration: FIG. 62.--Beetle Mite.]
-
-These parasites, with their host, came into my possession in a strange
-way. A friend, who knew my hobbies, told me that he had managed to
-procure for me some young beetles just born. I ventured to suggest that
-beetles were not born as beetles, but in quite a different shape. My
-suggestion was received unsympathetically, and I was told that I should
-alter my opinion when the creatures were sent me. But I did not. The
-box contained a Dung Beetle, over which were swarming scores of these
-little Mites, and I had some difficulty in convincing the gentleman
-who sent them to me that these Mites were not the young of the beetle.
-
-We should compare this Beetle Mite with the Water Mite, and notice the
-difference in the mouth parts and the legs, which have a large pad
-between the claws.
-
-We may find another Beetle Mite, closely allied to this species, on the
-Devil’s Coach Horse, and some of its near relations. This Mite was also
-known to De Geer[38], whose remarks upon it are worth quoting, in a
-condensed form.
-
-He found a beetle covered with these Mites, and on examining them with
-a hand lens saw that they were attached to their host by a long thread
-or stalk, which came from the posterior end of the body. Several Mites,
-he tells us, were joined together by one thread which fastened them all
-to the beetle; and he came to the conclusion that the parasites were
-nourished at the expense of the beetle, the thread serving to convey
-the juices of its body to them.
-
-‘It is very singular,’ he says, ‘to see living insects planted on the
-body of larger insects, from which they draw their subsistence by means
-of a thread or stalk.’ And then he goes on to compare these ‘vegetative
-Mites,’ as he calls them, with the ‘eggs’ of the Water Mites, which
-he found on Dytiscus and the Water Scorpion. The thread exists, and
-the Mites are attached by it to their host, but they do not draw
-nourishment through it from the beetle, for it is composed of their
-excrements.
-
-The Myriapods are worm-shaped creatures, breathing by means of
-air-tubes, and furnished with a number of limbs closely resembling
-each other. There are two groups: the Centipedes and the Millepedes.
-The former have the body flattened, with one pair of appendages to each
-segment, the first pair being modified into piercing poison-organs, and
-they feed on living prey. The body of the Millepedes is round, with two
-pairs of appendages to each segment; they have no poison-organs, and
-their food consists chiefly, if not entirely, of vegetable matter.
-
-There seems to be some doubt, however, as to whether _Ju´lus_, one
-of the commonest Millepedes, does not occasionally indulge in animal
-food. In _Nature Notes_ (Jan. 1896) there was a review of the
-_Cambridge Natural History_ (vol. v). The reviewer, in a brief
-summary of Mr. Sinclair’s part of the book (the Myriapods), said,
-after describing the Centipedes: ‘The millepedes, on the contrary, are
-sluggish vegetarians, with hard, cylindrical bodies, &c.’ On this a
-correspondent wrote in the March number: ‘Some time ago my attention
-was attracted to a large earthworm, writhing and twisting about on
-the garden path, as though in pain, or through having received some
-injury. On examining it more closely to ascertain the cause of its
-unusual movements, I found that a millepede had fastened itself to the
-side of the worm, and appeared to be boring or eating its way into
-the body, whilst the most violent efforts on the part of the worm
-were ineffectual in shaking off its antagonist. If the millepede is
-a vegetarian, what could be its object in attacking so harmless and
-defenceless a creature as the earthworm? The above, which I take to
-be a millepede, is the black or dark-coloured creature “with hard,
-cylindrical body” ordinarily found coiled up in a spiral under stones
-or rubbish.’
-
-The editor, as a matter of course, referred the matter to the writer
-of the review. His reply was as follows: ‘If there is no mistake
-about the identity of the aggressor in the account cited above, the
-observation is one of considerable interest; for, so far as we are
-aware, it is the only case on record of a millepede being guilty
-of such conduct. But were it not for the positive statement that
-the species was the dark-coloured creature with a hard, cylindrical
-body, which is ordinarily found coiled up in a spiral under stones
-or rubbish--a description which exactly applies to the millepedes of
-the genus _Julus_--we should have concluded without hesitation
-that the struggle in question was merely one of those that habitually
-takes place between the centipedes of the genera _Litho´bius_ or
-_Geoph´ilus_ and the earthworms upon which they feed.’
-
-Both the Centipedes and Millepedes are shy, light-shunning animals,
-and if we turn over some stones in the garden or in a walk through the
-fields we shall probably find specimens enough to serve us in getting
-some idea of both groups.
-
-The Centipedes are sometimes called ‘Hundred-legs,’ but this implies
-the possession of many more legs than the creatures really have. In
-Norfolk and Suffolk the people call them ‘Forty-legs,’ and this is much
-nearer the mark.
-
-_Litho´bius forfica´tus_, about an inch long and rufous brown in
-colour, is extremely abundant under stones and the bark of trees, and
-in cellars and outhouses. These animals run with great rapidity when
-disturbed, so that one needs to be on the alert to seize them when
-they are driven from the places in which they lurk. The body has nine
-principal and six subsidiary or smaller rings, and there are fifteen
-pairs of walking legs, besides the first pair, which are modified to
-serve as poison-organs. De Geer says that he never dared to pick up
-these Centipedes with ungloved hands, because he had seen a fly, which
-had been bitten by one, die on the spot, ‘which seems to be a sign that
-their bite is venomous.’ He examined their modified legs with a good
-microscope, but could not distinguish any opening. There is, however,
-an opening, as De Geer suspected, though he could not distinguish it;
-it lies near the point, and we may also trace the canal through the
-claw down to the poison-glands which lie, one on each side, at the base
-of the claws. The mouth parts resemble those of insects, and may be
-dissected out in the same way. When this Centipede walks, says De Geer,
-it does not use the last four pairs of legs, but drags them after it;
-but when it walks backwards, which it does as well as forwards, it then
-makes use of these four pairs of legs in the same way as the others. If
-we keep Lithobius alive we shall see that it can walk backwards, though
-it can scarcely be said to go as well one way as the other. From the
-same old writer some useful hints as to the method of keeping these
-animals may be gathered. Those that he kept in a vessel without any
-moisture soon died, and were quite dried up in twenty-four hours, which
-will teach us to keep them in a vessel with damp earth, shaded from
-light and heat.
-
-Dr. Sharp[39] gives some interesting details about the breeding habits
-of Lithobius, and describes, for the first time, the uses of the two
-hooks on the under surface of the body of the female.
-
-He experimented with Centipedes and Millepedes. Keeping them in large
-shallow glass vessels, the bottom of which was covered with a layer
-of earth, he fed the specimens of Lithobius on insects and worms, and
-sometimes on raw chopped meat, but they did not thrive on this as they
-did on prey which they could kill for themselves.
-
-  [Illustration: FIG. 63.--_A._ _Lithobius
-  forficatus._ _B._ Mouth parts seen from below (After
-  Graber.)]
-
-Lithobius, he tells us, lays but few eggs compared with the number
-deposited by Julus. Each egg, as it leaves the oviduct, is received
-by the hooks mentioned above, and by means of them it is rolled on
-the soil till a covering of earth adheres to the viscous material
-with which the egg is coated. The male considers the eggs special
-delicacies, and devours them whenever he has the opportunity. It is to
-prevent this that the female covers them with earth, so that the male
-may not recognize them.
-
-Geophilus is a much longer animal than Lithobius, for its body may
-consist of from 80 to 180 rings. The species have no eyes. Several of
-them are common, especially in the south of England, and possess, as
-do many genera of the same family, the property of phosphorescence,
-whence have arisen the stories of ‘luminous earthworms’ current from
-time to time. _Geophilus crassipes_ is the form most frequently
-captured when displaying its light. It is from one inch to two inches
-long, of a reddish-orange colour, and somewhat worm-like in shape. Mr.
-Pocock, of the British Museum (Natural History), says: ‘The property
-of luminosity lies in an adhesive fluid secreted by glands which open
-upon the lower surface of the body, and the power of discharging or
-retaining the fluid appears to be entirely under the centipede’s
-control. The phenomenon is observable during the autumn months, from
-about the middle of September to the end of November, and although its
-significance is not clearly understood, it is generally believed to be
-connected with the pairing of the sexes[40].’
-
-During a visit to the seaside it is well to look out for specimens of
-a marine Centipede, which is, apparently, not very common. It is said
-to occur ‘under stones and sea-weeds on the shore at or near Plymouth’;
-and in 1895 I had the good fortune to meet with one at Bexhill.
-This Centipede does not live in the sea, but will survive prolonged
-immersion in salt water. It is far too valuable for us to pick to
-pieces, so that, if we should have the good fortune to meet with one,
-we should carefully examine it, making what notes are necessary, and
-then pickle the specimen and send it to the British Museum, Cromwell
-Road, S.W. The tube should be labelled with the place and date of
-capture, and it should be stated on the label whether the animal was
-taken above or below high-water mark.
-
-The Common Millepede--often miscalled the wireworm--is readily
-distinguished by the absence of poison-claws, and its cylindrical
-worm-like appearance. De Geer, who of course adopted the Linnaean
-definition of ‘Insects,’ says of the Millepedes of the genus Julus, to
-which our Common Millepede (_Ju´lus terres´tris_) belongs: ‘They
-form, as it were, the last link of the chain which unites the class of
-Insects to that of Worms, for the body is elongated and cylindrical;
-and though they have a great number of feet, these are so short, that
-when these animals walk, they seem rather to glide along after the
-fashion of legless worms[41].’
-
-  [Illustration: FIG. 64.--The Common Millepede.]
-
-Dr. Sharp says that these animals do very well in confinement, and he
-found that sliced apples and grass formed the best food for them. He
-watched the process of nest-making and egg-laying, and these creatures
-are so abundant, and the necessary appliances so simple, that we may
-follow his example and see it for ourselves. His arrangements were the
-same as for Lithobius, and he saw the female make a hollow sphere of a
-bit of earth, stuck together by the secretion from the salivary glands,
-and smooth on the inside. A small hole was left on the top, and through
-this she passed in from 60 to 100 eggs, closing the aperture with earth
-moistened with the salivary secretion. The eggs were hatched in about
-twelve days. The young of all the Myriapods when they leave the egg
-have but three pairs of legs, but the number of limbs and segments is
-increased at each successive moult.
-
-Having watched our Millepedes in confinement, it will be well to take a
-preserved specimen and examine it carefully with the pocket lens, so as
-to compare it with the Centipede; then to compare both with the common
-earthworm, and to note the points of likeness and of difference. The
-dark spots on each segment in the illustration show the stigmata.
-
-  [Illustration: FIG. 65.--Segments of Millepede
-  (magnified).]
-
-
-
-
-                               CHAPTER V
-
-              CRUSTACEANS.--PRAWN, SHRIMP, MYSIS, CRABS;
-                          AMPHIPODS; ISOPODS
-
-
-The next group of Arthropod animals with which we have to deal is that
-of the Crusta´cea. Some or other of the members of this class are
-well known to everybody, if only in the shape of toothsome food--the
-Prawn, the Shrimp, the Lobster, the Crayfish, and the Crab. The great
-characteristic of this class of the Arthropod phylum is the so-called
-‘shell,’ which differs greatly from true shell in being composed of
-chitine, hardened with salts of lime. Most of the species live in the
-water and breathe by means of gills or through the skin. In dealing
-with these creatures, some long words must be employed, if our present
-work on them is to be a stepping-stone to something more advanced. The
-difficulty is more apparent than real, and if boldly faced will soon be
-overcome.
-
-Our first division, or sub-class, of the Crusta´cea is that of the
-Malacos´traca, or animals with soft shells--a name originally adopted,
-as Mr. Stebbing tells us[42], ‘to distinguish such creatures as crabs
-and crawfish and prawns from such others as oysters and clams; not
-because of the absolute, but because of the comparative softness
-of their shells.’ Under this sub-class are grouped two Orders--the
-Stalked-eyed and the Sessile-eyed Crustaceans, the technical names for
-which are the Podophthal´ma and the Edriophthal´ma.
-
-To the Stalked-eyed Crustaceans belong the Prawn, the Shrimp, Mysis,
-or the Opossum Shrimp, and the Crabs, to mention only those forms with
-which we are dealing here. The reason for scientific and popular names
-will be evident if living or spirit specimens are examined, for it will
-be seen that the eyes are elevated on stalks. Mr. Stebbing[43] relates
-an amusing story of a very intelligent student, who, on being told that
-the eyes (of the shrimp) were stalked, candidly confessed to having
-always thought that this appearance was due to their having been forced
-out of the head by boiling.
-
-The general shape of a Prawn (_Palaemon serratus_) is fairly familiar
-to everybody. The body is divided into two principal regions--the
-carapace, or cephalothorax, as it used to be called (formed by the
-union of the head and thorax), and the pleon, or swimming part. The
-carapace has a projecting beak or rostrum, and is unsegmented; the
-pleon is divided into segments, and the whole may be represented thus:--
-
-    ----  -- -- -- -- -- --  )
-     _c_   1  2  3  4  5  6 _t_
-
-where the long stroke (_c_) stands for the carapace, the shorter ones
-(1–6) for the segments of the pleon, and the ) for the telson or tail.
-The carapace consists of fourteen united segments, and this will give
-twenty or twenty-one segments in all, according as we reckon the telson
-an appendage of the sixth segment of the abdomen, or as a distinct
-segment. The carapace bears the eyes, two pairs of antennae, six pairs
-of mouth appendages, and five pairs of walking legs or perei´opods,
-normally with seven joints--in all, fourteen pairs of appendages, that
-is, one pair for each of the fourteen segments of which the carapace
-is composed. The segments 1–5 of the ple´on bear swimming feet, or
-ple´opods, and the female uses these for retaining the eggs, which she
-bears about with her. In this fashion the ‘hen’ lobster carries her
-‘berries.’
-
-The Prawn is a capital inmate of the aquarium, and as it does well
-in confinement, specimens should be kept in order to get a general
-acquaintance with their form and external anatomy, and to watch their
-habits. The Common Prawn will answer the purpose, but still better is
-_Palaemone´tes varians_, an exceedingly common species. It has
-this advantage, that it ‘seems to be equally at home in salt water
-and fresh.’ The only condition necessary is a good supply of food,
-and this may be furnished by putting into the aquarium from time to
-time a quantity of water-fleas. If these Prawns are well fed they will
-shed their skins at frequent intervals, and this operation will give
-us material for examination, for the cast skin will serve our purpose
-almost as well as a spirit specimen.
-
-Some of these Prawns are now living in one of my aquaria. They were
-taken in a brackish dyke or cut near Newhaven, in Sussex, and in
-the mud which was brought back with them were a number of small
-bivalves of the genus _Sphaerium_. Most people know Mr. Kew’s
-exceedingly interesting book, _The Dispersal of Shells_[44].
-In it he relates some extraordinary instances of the way in which
-species of shells are carried short distances, and may be carried
-from one district or country to another. These Prawns offered a good
-illustration of this, and practically confirmed some of the statements
-in his book, for on several occasions they were seen with the bivalve
-shells attached to their walking legs. The molluscs lay half buried
-in the mud and vegetable _débris_ at the bottom of the tank,
-and as the Prawns walked about they sometimes trod between the open
-valves, which, as they closed, fastened on to the intruding limb. On
-one occasion the molluscs did not relax their grasp for days; and had
-this incident occurred when the creatures were at liberty the molluscs
-might have been carried for a considerable distance. If specimens of
-_Sphaerium_ are put into an aquarium containing Prawns of this
-kind, it is probable that before very long the crustaceans will have
-one or two attached to some of their limbs.
-
-Prawns are exceedingly beautiful, and if we get hold of live specimens,
-from salt water or fresh, they should be put into an aquarium--the
-smaller, in reason, the better--so that their motions may be watched
-with the hand lens. If much weed be put in, the Prawns will use their
-walking legs in preference, while if there is little vegetation the
-powerful tail-fan will be employed for motion backwards, while the five
-pairs of limbs on the abdomen enable their owners to move forwards
-through the water.
-
-From Fig. 66 one may get a good notion of a Prawn, and of the points
-in which Prawns, in the zoological sense of the word, differ from
-Shrimps. The head of the Prawn is armed in front with a long blade-like
-beak, studded along its upper and lower edges with a series of teeth
-like those of a saw, and the second leg is chelate, that is, armed with
-pincers, resembling, in miniature, that of a lobster or crab. In the
-Shrimp, on the contrary, there is scarcely a trace of the beak, and
-the first leg is incompletely chelate, or sub-chelate[45] (Fig. 67),
-its last joint folding back upon the one that supports it, just as the
-blade of a pocket-knife closes on its handle. These two distinctions
-hold good between all Prawns and all true Shrimps.
-
-  [Illustration: FIG. 66.--Prawn.]
-
-Now let us go over our Prawn--a spirit specimen--in detail. The
-antennae may be separated, and examined, and the appendages of the
-inner pair distinguished, for at first it may be thought that there
-are more than two pairs. This, however, is not the case, as should be
-ascertained by actual investigation. A needle inserted at the base of
-the outer antennae will separate the first three segments, bearing
-respectively the eyes, and the first and second pairs of antennae.
-The eye should be carefully looked at to make out that it is really
-compound. Then the joints of the antennae, each with its circle of
-sense-hairs, are to be noticed. Last of all, the inner pair of antennae
-deserve attention, for these carry in the basal joint an organ of
-hearing. This joint is large and sac-like, and contains an opening
-through which grains of sand are introduced by the animal itself. The
-grains serve to transmit the vibrations of the water in the sac to the
-auditory hairs, to each of which a branch is sent off from the auditory
-nerve. If the joint is opened the sand will be found. The first
-antennae of a lobster or crayfish may also be examined and compared.
-
-The mouth organs, of which there are six pairs, will offer some
-difficulty, and for this reason it may be well to pass them over in
-this case and to deal with these organs generally when treating of the
-Crab.
-
-Beneath the outer foot-jaws are the first pair of walking feet, which
-are used as cleansing organs. Gosse describes them as ‘beset with hairs
-which stand out at right angles to the length of the limb, radiating in
-all directions like the bristles of a bottle-brush.’ If we watch our
-Prawn in life, we shall frequently see these limbs in active operation.
-They are brought to bear on every part of the body within reach.
-Sowerby says[46]: ‘The prawn loves to be clean, and he takes surprising
-pains to keep himself so. Drawing up his tail and abdomen, he subjects
-their under surface to the most careful revision, scrubbing and poking
-between the lappets of the shell and body, diving into every crevice,
-and with the pincer-hand picking out every speck too large to brush
-away.’ The next pair of legs are also chelate; but the three following
-pairs are armed with claws, and it is upon the points of these that the
-animal walks on the bottom. The pincers of the second pair of legs are
-used to pick up food and bring it up to the mouth organs, where it is
-taken by the outer foot-jaws, and passed into the mouth. The swimming
-feet carry two branches, finely fringed with hairs.
-
-  [Illustration: FIG. 67. First walking leg of Shrimp
-  (enlarged).]
-
-If the carapace be removed the gills at the base of the walking feet
-will be exposed. These consist of thin leaf-like plates attached to a
-central stalk, and they are aërated by water passing in behind and out
-in front.
-
-After what has been said of the Prawn, little space need be devoted
-to the Shrimp, for it may be gone over in precisely the same way. It
-will be sufficient to call attention to the difference in the antennae,
-to the rudimentary rostrum or beak, and to emphasize the distinction
-between the terminal joints of the first leg in the two creatures. The
-leg shown in Fig. 67 corresponds to the limb used for cleansing by the
-Prawn.
-
-There is a great difference in their habits, for Shrimps burrow in the
-sand for concealment. In doing this the swimming feet, as well as the
-walking legs, are brought into action, and when the Shrimp is settling
-down, sand is swept over its back by the antennae, to render the
-concealment complete.
-
-In many of the rock-pools round the coast, and also in brackish water,
-Mysis, or the Opossum Shrimp, may be met with. It is not, so far as my
-experience goes, a good inmate of the aquarium, but it is extremely
-interesting from the fact that, unlike its higher relations, the
-auditory apparatus is not situated in the antennae, but in the plates
-of the telson (Fig. 68E).
-
-  [Illustration: FIG. 68.--Mysis, or the Opossum Shrimp.]
-
-Mysis is shrimp-like in general appearance but differs from Shrimps
-in the structure of the legs, in the absence of gills, and in other
-particulars.
-
-The telson consists of five pieces. In each of the two inner and
-smaller pieces is an oval sac, like that described in the basal joints
-of the first antennae of the Prawn, containing a single lens-shaped
-otolith, consisting of chalky matter embedded in some organic substance.
-
-‘The vibration of the hairs [in this sac] is mechanical, not depending
-on the life of the animal. Hensen took a Mysis, and fixed it in such
-a position that he could watch particular hairs with a microscope. He
-then sounded a scale; to most of the notes the hairs remained entirely
-passive, but to some one it responded so violently and vibrated so
-rapidly as to become invisible. When the note ceased the hair became
-quiet; as soon as it was re-sounded, the hair at once began to vibrate
-again. Other hairs, in the same way, responded to other notes. The
-relation of the hairs to particular notes is probably determined by
-various conditions; for instance, by the length, thickness, &c.[47]’
-
-We shall not be able at present to repeat Hensen’s experiment, but we
-may break up the sac and extract the otolith, which may be seen with
-the lenses at our command.
-
-Small specimens of the Shore Crab (_Car´cinus mae´nas_) are fair
-game for us. They will interest us while living in the aquarium, and
-when dead we can put them into pickle, and break them up at our leisure.
-
-The broad shell of the Crab--the crab-cart of children--corresponds
-to the carapace of the Lobster, the Prawn, and the Shrimp, and bears
-the same number of appendages--fourteen pairs. To make out the pleon
-or swimming part, it is only necessary to lay the crab on its back,
-and, with a needle, or small knife, turn back the flap--or ‘apron,’
-as fishermen call it--which lies in a groove on the under surface.
-Here we shall find the pleopods, or swimming feet, though they are not
-really used for that purpose. The eyes, the two pairs of antennae,
-and the five pairs of walking legs will offer no difficulty. It is
-only necessary to remark that the terminal joints of the last pair of
-walking legs are flattened and fringed with hair, showing some approach
-to the swimming crabs, which use those organs to swim with.
-
-Now we may examine the mouth organs, of which there are six pairs.
-To do this, the crab may be fixed, with the back downwards, or held
-lightly but firmly in the left hand. The latter plan is perhaps the
-more convenient. The index and middle fingers should support the
-carapace, and the thumb should be placed on the pleon. The outer pair
-of mouth organs are the third maxillipedes, or jaw-feet. These close
-the area of the mouth, somewhat after the fashion of the double-doors
-of a cupboard, though the hinging, of course, is different. To open
-these jaw-feet, a needle should be inserted at the top, with a gentle
-pressure downwards and outwards. The back of the crab is turned away
-from us, so that the left jaw-foot should be pressed outwards to the
-right, and the right jaw-foot to the left.
-
-Theoretically these limbs consist of the same number of joints as
-the perei´opods or walking legs; and this is to be borne in mind,
-even if we do not succeed--and we probably shall not--in tracing the
-full number of seven joints. But we may notice and count the terminal
-joints, and observe the fringing of the limb with hair.
-
-A similar method of using the needle will enable us to raise the second
-and first pairs of maxillipedes, which are of smaller size and softer
-structure.
-
-Having raised these organs, it is well to replace them--to close the
-doors, as it were--and then to raise them again, to observe how they
-work. They may then be detached and fastened to a small piece of card,
-for comparison with similar organs in the lobster and the crayfish, and
-with the mouth organs of insects.
-
-Beneath the maxillipedes are the second and first maxillae--thin,
-leaf-like organs. The first-named are furnished with spoon-like scoops,
-which serve to carry out from the gill-chamber the water that has
-parted with its oxygen in aërating the gills.
-
-Immediately below the maxillae lie the mandibles, with hard, cutting
-edges, by means of which the food is broken up. Each carries a palp.
-
-  [Illustration: FIG. 69.--Maxillipedes and Maxilla
-  (_b_) of Shore Crab. (_d_) First maxillipede. (After
-  Savigny.)]
-
-These inner three pairs should also be detached, and the whole of the
-mouth organs arranged on a card thus:--
-
-    MANDIBLES.
-    FIRST MAXILLAE.
-    SECOND MAXILLAE.
-    FIRST MAXILLIPEDES.
-    SECOND MAXILLIPEDES.
-    THIRD MAXILLIPEDES.
-
-The first attempt will certainly be unsuccessful; and the first few
-attempts will probably be unsatisfactory; but we shall gain knowledge
-with each successive trial. And knowledge is worth the winning.
-
-The stomach is interesting, and the gastric mill may be easily
-examined. When the mouth organs are removed, there will be no
-difficulty in taking out the stomach. This should be cut open with a
-needle, and then we shall see the gastric teeth (_g_ _g_)
-which grind up the food against the fixed calcareous plate (_b_
-_b_). The lower end of the stomach is set with fine hairs, which
-prevent the passage of food into the intestines until it has been
-ground fine between these living millstones. A similar arrangement is
-found in all the higher Crustacea. The time spent in comparing the
-gastric mill of the Crab with the ‘gizzard’ of the Cockroach will not
-be thrown away.
-
-The Broad-clawed Porcelain Crab (_Porcella´na platyche´les_) is
-also worth keeping, for it is a droll little creature. These crabs
-are generally to be found clinging to the under surface of stones or
-of ledges of rocks overhanging small pools. The chief interest of
-these crabs, for us, lies in the exceedingly beautiful arrangement for
-procuring food with which the outer pair of foot-jaws is furnished.
-
-  [Illustration:
-
-   FIG. 70.--Stomach of Crab laid open. _b_ _b_
-   _b_, fixed plate, against which the gastric teeth _g_
-   _g_ are opposed; _b´_ _b´_, gastric teeth
-   enlarged.]
-
-‘Watching a Broad-claw beneath a stone close to the side of my tank, I
-noticed that his long antennae were continually flirted about; these
-are doubtless sensitive organs of touch, or some analogous sense,
-which inform the animal of the presence, and perhaps of the nature,
-of objects within reach. At the same time I remarked that the outer
-foot-jaws (pedipalps) were employed alternately in making casts, being
-thrown out deliberately, but without intermission, and drawn in,
-exactly in the manner of the fringed hand of a Barnacle, of which both
-the organ and the action strongly reminded me. I looked at this more
-closely with the aid of a lens: each foot-jaw formed a perfect spoon
-of hairs, which at every cast expanded and partly closed. That you may
-understand this better, I must say that the foot-jaw resembles a sickle
-in form, being composed of five joints, of which the last four are
-curved like the blade of that implement. Each of these joints is set
-along its inner edge with a row of parallel bristles, of which those
-of the last joint arch out in a semicircle, continuing the curve of
-the limb; the rest of the bristles are curved parallel or concentrical
-with these, but diminish in length as they recede downwards. It will be
-seen, therefore, that when the joints of the foot-jaw are thrown out,
-approaching to a straight line, the curved hairs are made to diverge;
-but as the cast is made they resume their parallelism, and sweep in, as
-with a net, the atoms of the embraced water[48].’
-
-All this description may be verified from a spirit specimen, if the
-foot-jaws be carefully removed. And the examination with the lens will
-also show that these hairs are plumose, that is, set with smaller hair,
-like the barbs of a feather.
-
-At this point we may conveniently take leave of the Stalk-eyed, and
-pass on to the Sessile-eyed, Crustacea. Leaving the Cuma´cea out
-of the question, we have two Sub-orders from which to choose our
-subjects--the Amphip´oda and the Isop´oda--conveniently Englished,
-Am´phipods and I´sopods. We learn from Mr. Stebbing[49] that ‘the
-Amphip´oda, which are common in fresh as well as in salt water, were
-so named by the French naturalist Latreille, as having feet extending
-in all directions, their limbs at the same time having much diversity
-of form, in correspondence with diversity of function. The Isop´oda,
-or equalfooted animals, besides being found both in fresh and salt
-water, have more decidedly than the Amphip´oda extended their range
-to the dry land. The name was invented by Latreille in ignorance of
-the great number of species, since investigated, in which the feet are
-strikingly unlike and unequal. Nevertheless, the name may stand, just
-as a rose remains a rose even when it is not rose-coloured.’ These last
-two sentences must be borne in mind, for they throw great light on a
-subject that may give us some trouble--the question of priority in
-nomenclature.
-
-The majority of the Amphipods live in salt water, but a few are found
-in ponds and streams, and some dwell on the shore, near, but not in,
-the sea. The animals of this Sub-order are distinctly segmented, and
-three regions may be distinguished thus [image], where C stands for
-the Cephalon, or head, Per. for the Perei´on, or body, and Pl. for
-the Ple´on (literally, the swimming part), or tail. On the head we
-shall find two pairs of antennae, the eyes, and the mouth appendages.
-Each segment of the perei´on bears a pair of appendages; the first
-two pairs are called respectively the first and second gnath´opods
-(or jaw-feet), and the other five pairs perei´opods, or walking feet.
-The pleon carries three pairs of ple´opods, or swimming feet, on the
-first three segments, and each of the following three has a pair of
-uropods or tail appendages. It is well to make out these parts in every
-specimen that comes in our way. More is learnt by breaking up one
-specimen than by reading the clearest description so often that one
-knows it by heart.
-
-  [Illustration: FIG. 71.--Gammarus. (After Sars.)]
-
-We may begin with the Fresh-water Shrimp (_Gam´marus pulex_),
-which may be taken abundantly in running water where there is plenty
-of vegetation. Willow-moss affords these Crustaceans a favourite
-hiding-place. It is an excellent plan to gather a quantity of
-weed and shake it over a newspaper or a piece of mackintosh. The
-‘Shrimps’--which, by the way, are not really Shrimps--will be dislodged
-from the weed, and we shall see them wriggling along on their sides,
-from which habit they and their near relatives are often called
-‘Scuds,’ and ‘Screws.’ They are useful inmates of an aquarium, because
-they feed on decaying animal matter, and so keep the water pure and
-sweet. Opinions are divided as to whether these animals feed on
-water-plants; it is probable that when their natural food fails them,
-they take what comes in their way. I have kept marine and fresh-water
-species of Gammarus (the genus to which the Fresh-water Shrimp belongs)
-in tanks which contained no other animals, but plenty of vegetation,
-and both lived and did well for a considerable time. They are by no
-means unwilling to make a meal off the dead body of one of their own
-species; but it is exceedingly doubtful if they prey on each other, as
-some old writers have asserted. This notion probably arose from the
-fact that the male carries the female, which is much smaller, about
-with him, during the period of courtship, holding her tightly beneath
-his body by means of the fingers of its first two pairs of hands. The
-habit is not confined to this genus, nor even to this Sub-order; for
-some, if not all, the species of Idotea carry on their courtship in
-similar fashion, as does also the Water Woodlouse. For the verification
-of statements such as these, a small aquarium is necessary, but the
-animals will not be under observation long before the observer will be
-convinced of their truth.
-
-All species of Gammarus, whether living in the sea or fresh water,
-may be readily distinguished by the rows of small spines on the three
-hinder segments of the pleon, for this is one of the characteristic
-marks of the genus. After we have kept specimens in the aquarium for
-a time, so as to become familiar with their general appearance and
-habits, we will put them to practical use by breaking them up.
-
-Our first task is to work over the animal as a whole, and to make
-out the three regions--ceph´alon, or head; pereī´on, or body; and
-plē´on, or swimming part, or tail--into which it is divisible. It
-will not be sufficient to do this once, and then to imagine we have
-the whole matter fixed in our memory. It should be repeated over and
-over again, with every specimen that comes into our hands, till we know
-these regions practically, and the number and kind of appendages they
-carry. And then the three rows of spines are to be looked for. For all
-this the inch lens will be quite sufficient.
-
-Now let us separate the head. When this is done, and if we use the
-lens, we shall at once be able to account for the name ‘Sessile-eyed
-Crustacea,’ for the difference between the eyes of our specimen and
-those of a shrimp or a crab will be evident. Nor can there be any doubt
-that they are compound eyes, though the outer integument is not divided
-into facets. The antennae are next to be considered. Of these there
-are two pairs, the superior, or inner, pair being the longer. These
-antennae consist of three basal joints and a many-jointed flagellum,
-or lash, and on each of the inner pair is a secondary appendage,
-arising from the distal (or outer) end of the third basal joint. We
-may represent one of the superior antennae thus: [image]. The dashes
-represent the three basal joints, the long row of dots the many-jointed
-flagellum, and the slanting row of dots stands for the secondary
-appendage. The sensory-hairs on the joints of the flagellum should be
-looked for, and may be made out with the inch lens. The same power will
-show the denticle, or tooth-like projection at the base of the lower
-antennae.
-
-Next come the mouth parts. As compared with Crabs, Amphipods seem badly
-off in this respect; for the second and third maxillipedes of the
-former become the first and second gnathopods of the latter, so that
-instead of six pairs of mouth organs the Amphipods have only four.
-
-It is not an easy matter for a beginner to separate the mouth parts
-of an Amphipod, but the difficulty is not insuperable, and will grow
-‘small by degrees and beautifully less’ with practice. We have to make
-out four pairs of organs arranged in the order given at the side of the
-page, the mandibles being the innermost.
-
-    MANDIBLES.
-    FIRST MAXILLAE.
-    SECOND MAXILLAE.
-    MAXILLIPEDES.
-
-Of course we must begin with the maxillipedes (Fig. 72). The specimen
-may be held between the finger and thumb, and the parts picked out with
-a needle. It is, however, better and easier to make the dissection
-under water. Then we can remove the second and first maxillae, the
-latter easily recognizable by its palp or feeler. Last of all come the
-mandibles, also bearing a palp. We shall _feel_ these under the
-needle, because of their hardened cutting edges. These are distinctly
-toothed. When practice has made the separation of these parts fairly
-easy, they should be compared with the mouth parts of other members of
-the group, so as to utilize the knowledge we have gained.
-
-  [Illustration: FIG. 72.--Maxillipedes of _Gammarus
-  marinus_ (in centre). _A._ First maxilla. _B._
-  Second maxilla (magnified).]
-
-Next come the two pairs of gnathopods, and in these we have to find
-seven joints--which may be denoted by the numbers 1, 2, 3, 4, 5, 6, 7;
-1 being the basal joint, or that nearest the body. The sixth joint is
-often called the ‘hand,’ and the seventh, the ‘finger.’ The joints vary
-greatly in different genera. The walking legs are next to be examined,
-and we may notice that the first and second pairs are turned forwards,
-and the third, fourth, and fifth pairs backwards. At the bases of these
-legs are the breathing apparatus, and the females have leaf-like plates
-on the anterior four pairs, forming a pouch in which the eggs are
-hatched, and here she shelters her young, and carries them about with
-her.
-
-The following account of this habit is taken from Bate and Westwood’s
-_Sessile-eyed Crustaceae_ (i. pp. 380, 381), and was furnished to
-the authors of that book by Dr. James Salter: ‘On catching a female
-with live larvae, nothing is seen of the progeny till the parent has
-become at home in the aquarium, when the little creatures leave her
-and swim about in her immediate neighbourhood. The plan I have adopted
-to watch this curious habit of maternal protection, has been to place
-a single individual in a bottle of sea water. After a time, and that
-soon, the little crustacean seems at ease and swims slowly about,
-when the young fry leave her and swarm around her in a perfect cloud;
-they never leave her for more than half or three-quarters of an inch,
-and as she slowly moves about they accompany her. If now one taps the
-side of the bottle with one’s finger-nail, the swarm of larvae rush
-under their parent, and in a second are out of sight. The parent now
-becomes excited, and swims about quickly, as if trying to escape;
-but by letting the bottle containing her rest quite still she soon
-gets composed, when out come the young larvae again and swim about
-as before. This may be repeated as often as the observer wishes, and
-always with the same result. I have only seen this in one species, but
-it is quite a common species in Poole Harbour, and I have watched the
-interesting habit many times.’
-
-The swimming legs are, roughly speaking, [image]-shaped--that is, they
-consist of a stem, carrying two many-jointed filaments, fringed with
-fine plumose hairs. A hair is said to be plumose when it bears smaller
-and finer hairs on each side. ‘By folding the tail beneath the body,
-and suddenly striking it out again, those animals which exist in the
-water, as well as those which live on the shore, are enabled to dart or
-leap to a considerable distance[50].’
-
-  [Illustration: FIG. 73.--Nest-building Amphipod. (From
-  life.)]
-
-Our hand lens may be well employed in watching some of the
-nest-building Amphipods at work in the aquarium. There can be no
-difficulty in keeping these creatures in captivity, and under
-observation, as they build their tubes and rear their families. They
-are plentiful in every rock pool round the coast, and it would be a
-hard matter to dip the net into any such pool without getting a few
-specimens.
-
-They need absolutely no care. The aquarium of the specimen figured
-was a four-ounce bottle, tightly corked; and in it was a spray of
-Cladophora, on which the animal fed, and the growth of which broke up
-the carbon dioxide and set free good store of oxygen. Here it lived for
-some months, and built more than one tube for itself against the side
-of the bottle.
-
-It is easy enough through the pocket lens to watch the Amphipod at
-work. Like other builders, the first thing it does is to get its
-materials ready. Lying on its side, with its back against the glass,
-it will rake together with its antennae and jaw-feet a good store of
-vegetable _débris_, or if there be no supply of this, will break
-off branches from the growing weed.
-
-But gathering vegetable _débris_, or even filaments of living
-weed, is very far from being tube-building. Something more is needed
-to bind the mass into a coherent structure. This the animal itself
-supplies. The bases of the first two pairs of walking feet are large,
-and contain glands which secrete a glutinous cement, that can be spread
-like mortar, or spun out into threads.
-
-An American observer devoted much time to the observation of these
-animals. He says[51]: ‘When captured and placed in a small zoophyte
-trough, with small branching algae, the individuals almost always
-proceeded at once to construct a tube, and could very readily be
-observed under the microscope.... The branches were not usually at once
-brought near enough together to serve as the framework of the tube, but
-were gradually brought together by pulling them in and fastening them
-a little at a time until they were brought into the proper position,
-where they were firmly held by means of a thick network of fine threads
-of cement spun from branch to branch. After the tube had assumed
-very nearly its completed form, it was still usually nothing but a
-transparent network of cement-threads woven among the branches of the
-weed.’
-
-Then he describes the method in which the Amphipod works up bits
-of weed and its own droppings into the framework of the tube. In
-putting its foecal pellets to this use, it reminds one of a species of
-Melicerta (_Melicerta janus_)[52], which employs the same material
-to coat its gelatinous sheath.
-
-In breaking up weed and pellets with its foot-jaws and (probably) its
-mandibles, the Amphipod recalls the practice of some of the Masking
-Crabs, which have been seen to apply to the mouth the material they
-were using to deck themselves. Dr. Aurivillius suggests that in the
-case of the Crabs there may be an adhesive secretion from the mouth,
-as there is possibly in the Amphipods. ‘The spinning was done wholly
-with the first and second pereiopods, the tips of which were touched,
-from point to point over the inside of the skeleton tube, in a way
-that recalled strongly the movements of the hands in playing upon a
-piano. The cement adhered at once to the points touched, and spun out
-between them in uniform delicate threads. The threads seemed to harden
-very quickly after they were spun, and did not seem, even from the
-first, to adhere to the animal itself. In one case, in which the entire
-construction of the tube was watched, the work was apparently very
-nearly or quite completed in little more than half an hour.’
-
-The species we are likely to meet with in rock-pools fashion their
-tubes in a similar way. The only difference to be noted is that they
-employ less cement, and a larger proportion of broken-down weed and
-other matters.
-
-The Sand-hopper (_Tali´trus locus´ta_) and the Shore-hopper
-(_Orches´tia littorea_) are so exceedingly plentiful that it may
-be well to collect and preserve some during any visit to the seaside.
-Both are of fairly large size, and present no great difficulty to us in
-making out their several parts. Let us take the Sand-hopper first.
-
-Sand-hoppers swarm on most sandy shores, where they perform the useful
-part of scavengers. They are always found above high-water mark, and
-do not enter the sea of their own accord. In hunting for them it is a
-good plan to turn over decaying masses of sea-weed, for under them the
-Sand-hoppers are sure to swarm.
-
-Strange tales have been told of their voracity. Bate and Westwood[53]
-record the story of a correspondent who says that at Whitsand he ‘saw
-“not millions, but cartloads,” of this species lying piled together
-along the margin of the sea. They hopped and leaped about, devouring
-each other, as if for very wantonness. A handkerchief, which a lady let
-fall amongst them, was soon reduced to a piece of open work by the
-minute jaws of these small creatures.’
-
-This statement has been copied into a good many books, without
-criticism. At last Mr. David Robertson tried various experiments with
-a view to discover if these creatures would feed on each other, or,
-failing other food, put up with cambric or muslin. The specimens upon
-which he made his observations did neither the one nor the other. Mr.
-Robertson embodied the results of his experiments in a paper which he
-read before the Natural History Society of Glasgow[54]. And the story
-may be read in an abbreviated form in the Rev. T. R. R. Stebbing’s
-_Naturalist of Cumbrae_, p. 329.
-
-In Gammarus we have a standard with which to compare our Sand-hopper.
-The first thing to notice is the difference in the antennae. Here the
-superior pair are very short, and carry no secondary appendage, and
-the lower pair have no denticle or tooth-like process. There is also
-considerable difference in the gnathopods, or jaw-feet, the sixth joint
-of which, in the Sand-hopper, does not form a ‘hand.’ The pleopods, or
-swimming feet, are small, and are used for leaping. We shall also find
-some difference in the details of the mouth parts, especially in the
-toothing of the mandibles.
-
-We now come naturally to the Isop´oda, which are distinguished by the
-nearly uniform size of the seven segments which constitute the trunk,
-and the seven pairs of limbs borne by these segments. The head is
-distinct, and the breathing apparatus is carried on the under side of
-the pleon--in these animals not the ‘swimming’ part--five pairs of
-plates lying one over another, sometimes covered by a larger outer pair.
-
-A normal I´sopod may be represented [image:--·······--], where the
-small dash will stand for the cephalon, or head; the seven dots for the
-segments of the perei´on, and the long dash for the pleon.
-
-The Common Asellus (_Asellus aquaticus_) of ponds and ditches
-is an excellent subject. It lives well in confinement, and if the
-conditions are fairly favourable, will increase and multiply. These
-animals will forage for themselves, and pick up a comfortable living
-from the vegetable _débris_ that always accumulates at the bottom
-of an aquarium, and they are not averse from an occasional meal of
-animal food.
-
-  [Illustration: FIG. 74. Water Woodlouse.]
-
-While our specimens of Asellus are moving about in any convenient
-vessel, we may verify with the hand lens what has been said about the
-general form. Then we may notice the antennae, the inner pair being
-much the smaller. There can be no difficulty in discriminating the head
-and the eyes; the seven segments of the perei´on, each bearing a pair
-of limbs; and the pleon with its two terminal appendages. These last
-consist of a stalk bearing two longer filaments, armed with spines, and
-ending in a small pencil of hairs.
-
-It is easy to see that the segments of the pleon have coalesced, so as
-to form a continuous plate or shield on the upper surface.
-
-If we now take our dissecting microscope and place an Asellus in some
-water in an excavated 3 in. by 1 in. slip on the stage, examination
-with an inch lens will show us a considerable amount of detail. With
-the half-inch Leitz lens (see p. 18) one may see quite clearly the
-beautifully annulated form of the flagella of the antennae, the sensory
-hairs with which these organs are set, and the circulation of the blood
-in the limbs and the antennae--the corpuscles moving in a continuous
-stream. More than this: we shall be able with the same power to
-distinguish tufts of Vorticellids that settle on the Asellus, and the
-commensal rotifers that roam about on the body of their host, generally
-on the limbs and under surface.
-
-Now we may turn the Asellus on its back, to examine the breathing
-apparatus more closely than we were able to do when the creature was
-moving about in the bottle. It will be easy to make out the opercular
-plates--modified tail appendages--that open and shut to admit water to,
-or allow it to flow out from, the true breathing-plates which function
-as gills, and correspond to the swimming feet of the Amphipods.
-
-In the female there is a pouch beneath the perei´on, in which the eggs
-are carried till they are hatched, and which serves as a nursery and
-refuge for the young.
-
-If a good number of these animals be collected they will probably
-breed, and then there will be the opportunity of seeing for ourselves
-the young carried about in the incubatory pouch.
-
-There are two other aquatic I´sopods which will make good subjects for
-us on account of their great abundance, and the ease with which they
-may be kept in any improvised aquarium, with a little weed. They may
-both be taken in brackish water, and will live and thrive in fresh
-water, without any admixture of salt. Indeed, both have lived for some
-months in a small bottle of New River water, in which the only weed is
-some willow moss. They feed on this and on the vegetable _débris_
-that accumulates at the bottom of the bottle, and both species have
-bred.
-
-The first is Idot´ea (_I. pelag´ica_), a long, narrow creature,
-with very short inner antennae. The last four segments of the pleon
-form a plate on the upper surface; and on the under surface the
-opercular plates may be opened like tiny folding-doors, to show the
-breathing plates.
-
-These vary greatly in colour. Of another species, Spence, Bate, and
-Westwood say: ‘According to our experience the colour of the animal is
-dependent upon that of the weed on which it lives. Those that live on
-the black fucus are generally very dark purple, while those that we
-find on the green algae are brightly verdant; and it has always been
-our opinion that this change was due to the food[55].’
-
-The other little creature is called Sphaero´ma--it has no English
-name--from the fact that it can roll itself into a ball. It is not
-difficult to identify, from the fact that all the segments of the pleon
-are joined into one plate, the hinder margin of which is entire, thus
-[image].
-
-The garden will afford us a hunting-ground for the last specimen of
-this group for which we have space--the Woodlice. Enough has been said
-of the method of looking over and breaking-up I´sopods generally to
-render detailed description unnecessary. The inner pair of antennae,
-however, are so small as to be readily overlooked: indeed, on first
-sight these creatures seem to have but a single pair. Some have, and
-others have not, the power of rolling themselves into a ball; and,
-concerning the former, Swammerdam tells the following story:--
-
-‘One of our maidservants had at one time found a great number of
-Woodlice in the garden, contracted into round balls ..., and thinking
-she had found a kind of coral beads, she began to put them one after
-another on a thread, but it soon happened that these little creatures,
-which roll themselves up in such a manner only for fear of harm, and
-appear as if they were dead, being obliged to throw off their mask,
-resumed their motions. On seeing which, the maidservant was so greatly
-astonished, that she threw away the Woodlice and the thread, and cried
-out, and ran away[56].’
-
-
-
-
-                              CHAPTER VI
-
-                         AQUATIC INSECT LARVAE
-
-
-In this chapter we shall deal with a few aquatic insect larvae. Of
-these, some are aquatic also in the perfect condition, while others
-emerge from the pupa stage as aërial insects. It requires no great
-amount of care to keep these creatures, and some hints on this subject
-and on collecting are given in the first chapter.
-
-The larva of Dytiscus is abundant during the greater part of the year,
-and is almost sure to be met with by the collector, who will find it
-an extremely interesting object for examination and study. No other
-creatures should be put in the same bottle with these larvae; and if
-there are several of them in one bottle, it is a good plan to put in
-plenty of pondweed, which will often keep them from attacking each
-other.
-
-When full grown, the Dytiscus larva may attain a length of two inches
-or rather more. Its colour is dingy brown, and its aspect forbidding
-enough to justify the uncomplimentary names that have been bestowed
-upon it--Water-devil and Water-tiger. It certainly rivals the tiger in
-fierceness, and its method of stealing up to its prey and attacking it
-from behind led Swammerdam to call it the Sicarius or Assassin Worm.
-
-One must not imagine that Swammerdam was ignorant of its nature; ‘worm’
-with him was a general term for any larval form. Indeed, he says,
-‘It is extremely probable that some peculiar species of the Water
-Beetle proceeds from this worm, when, having remained in the water a
-sufficient time, it betakes itself to the land to undergo its mutation;
-but this is mere conjecture.’ What was conjecture for him is fact for
-us.
-
-Now let us put our larva into a small tube, and examine it more
-closely. The head is large and joined to the first segment of the
-thorax by a distinct neck. There are twelve small eyes, six on each
-side, a pair of antennae, two pairs of palps, and a large pair of
-sickle-shaped mandibles, which Swammerdam calls ‘teeth,’ and says that
-‘it is perhaps to contain the muscles such teeth require that Nature
-has made the head so large.’ Behind the head come eleven segments, of
-which the first and last are the longest. They gradually increase in
-width till the sixth, the rest again decreasing, till the eleventh ends
-in a blunt point, from which diverge two appendages, thus [image],
-thickly fringed on both sides with hair, as are the tenth and eleventh
-segments.
-
-There are six legs, one pair to each of the first three segments.
-These also carry fringes of hair, thus increasing their power as
-swimming organs; and, in addition, they bear numerous spines, and end
-in strong double claws, which must be of service in climbing over
-aquatic vegetation, and may assist in holding a struggling victim or in
-striking it down, so as to bring it within reach of the mandibles.
-
-Spiracles will be found--seven on each side. These do not, however, in
-the larval condition, serve as breathing organs, though they fulfil
-their proper office in the pupa. The air-tubes of the larva open at the
-extremity of the last segment. When the larva wants to breathe it comes
-to the surface without an effort, for it is lighter than the water it
-displaces. The tail rises above the surface, and a fresh supply of air
-is taken in. When the larva wishes to descend, a stroke of the tail
-sends it downwards, and as it reaches the bottom of the tube it will
-cling with its claws to any weed we may have put in with it, or hold on
-with them to the glass itself.
-
-The chief interest of this animal lies in its mandibles, and the method
-in which they are employed. It was formerly believed that the mouth of
-this larva was closed, so that it could not take solid food, and that
-it lived entirely on the juices of its prey, which it sucked up through
-its hollow mandibles.
-
-Swammerdam says of this larva, ‘When about to eat he seizes with the
-two teeth (mandibles) the little creatures that come in his way, and
-pierces their body with the sharp crooked points. The teeth being
-perforated from the points to the roots, he in a surprising manner
-sucks through them into his mouth the blood of the unfortunate captive.
-This may be easily seen, especially when the blood of his prey is of a
-red colour, as the teeth are transparent.’
-
-He then describes how he watched one of these larvae feed, and saw the
-blood, mixed with air-bubbles, travel up the mandibles. After this he
-tells us how, if we have a Dytiscus larva, we may ‘procure ourselves
-a very entertaining and surprising sight, by throwing to it a small
-earthworm; for let this last move, twine, and otherwise bestir itself
-ever so much, the other keeps its hold, and very calmly sucks the blood
-of its prisoner.’
-
-We may, however, go to work in another fashion. We may dissect out the
-mandibles from a dead larva and pass a fine hair into the slit near the
-point, and it will come out at the orifice near the base. It is through
-this orifice that the nutritive juices of the prey are drawn into the
-true mouth. This practical proof that the mandibles are pierced is by
-no means so difficult as one might suppose.
-
-De Geer[57] seems to have been the first to suggest that there must
-be some kind of true mouth, and in support of his suggestion tells us
-that he saw this larva eating up the solid parts of a Water Woodlouse
-(_cloporte_), after having sucked up its juices. More than this,
-he places the mouth in what has proved to be the true position, though
-he did not solve the mystery as to why it is kept so firmly closed.
-This was done by Mr. Burgess, an American naturalist, from whose
-paper[58] the following particulars are condensed:--
-
-‘Authors have described this creature as mouthless; and if we examine
-the slit where we should expect the mouth to be, we find that this slit
-ends in a perfectly closed seam. The methods of microscopical research
-were brought into play, and a longitudinal section of the head cut and
-mounted. This showed that the upper and lower lips were locked together
-by a peculiar joint--the upper coming over and locking into the under
-lip (Fig. 75).’
-
-We may get some idea of this mouth-lock by placing the fingers of the
-right hand over those of the left, and then bending them.
-
-Mr. Burgess concludes his paper thus: ‘We find that the Water-tiger,
-far from being mouthless, as ordinarily assumed, has in fact a
-very wide mouth, though its lips are closely locked together by a
-dove-tailed grooved joint developed for this purpose. Whether this
-joint can be unlocked by the animal itself is another question, which
-I cannot answer, though De Geer’s observation above quoted makes this
-probable. It is, at all events, easy to open the mouth by manipulation
-with a pair of forceps.’
-
-  [Illustration: FIG. 75.--Mouth-lock. _m_, mouth ×
-  125. (After Burgess.)]
-
-Professor Miall[59] has verified Burgess’s observations, and carried
-them a step further. He found by actual experiment that ‘the mouth-lock
-acted automatically, opening when the mandibles opened, and closing
-when they closed.’
-
-Both these authorities stand very high. Yet, with all respect to them,
-it will be well to test these statements before accepting them.
-
-Something of this mouth-lock may be seen in any well-prepared slide
-of a Dytiscus larva. If we hold the slide up to the light and examine
-with a power of 10, we shall see a dark line--in some cases two nearly
-parallel thinner lines--running from the base of one mandible to the
-base of the other. The dark line is the closed mouth-lock. The two
-nearly parallel thinner lines are the edges of the lips drawn asunder
-in preparing the specimen or by the pressure of the cover-glass. If we
-get to see this much, we shall have advanced one step.
-
-  [Illustration: FIG. 76.--Dytiscus Larvae.]
-
-Next we may verify Professor Miall’s experiment, though not quite in
-his way, for such section-cutting as he speaks of is beyond our powers.
-Larvae as large as possible should be chosen, and killed by dropping
-them into boiling water. The mandibles of one should be allowed to
-remain closed, and those of the other plugged open with pith or a small
-piece of wood--a bit of a match will serve. By putting each in turn
-into an excavated slip with water, carefully covering this with a plain
-slip, and holding these slips together with an elastic band, we may
-examine the larvae as we did the slide.
-
-The result will be practically the same. Where the mandibles are
-closed, we shall see the dark line; and where they are open, we shall
-see the two thinner ones nearly parallel.
-
-One caution may be necessary. The mandibles bear at the base a
-rounded process, which fits into a chitinous cup. It is not difficult
-to mistake this for the mouth-lock, with which, however, it is not
-connected.
-
-There is still one other method which we may adopt to see the mouth.
-The head of one of these larvae may be cut off, dropped into a strong
-solution of caustic potash, where it should remain for a day or two.
-After washing it well in water, cut it in half lengthways, and turning
-either half upon its side, so as to expose the part cut, examine with
-the pocket lens.
-
-These experiments are by no means difficult. But if carried out step
-by step, it will be easy to understand how the larva can suck out the
-juices of its prey, and how it can open its mouth to swallow some of
-the solid parts.
-
-The larva does not readily change into a pupa in confinement. If,
-however, we wish to rear a beetle, the larva must be plentifully
-supplied with food, and removed from a bottle to a flat dish,
-where earth can be placed against the side so as to rise above the
-water-level. Fig. 77, where a pupa is represented in a bank by the side
-of a pond, will give us a hint how to go to work. The time occupied in
-pupation will vary according to the temperature of the room--but is
-never less than a fortnight. In the open it is probable that the winter
-is passed in the pupal condition, the perfect insect emerging in the
-spring. Like Land Beetles, it does not assume its dark hue for some
-days, but its pale skin darkens by degrees.
-
-  [Illustration: FIG. 77.--Pupa of Dytiscus.]
-
-The larva of Hydrophilus does not seem to be often taken in this
-country. It would make a capital subject for investigation, and the
-food-supply could be arranged easily enough. The repetition of the
-experiences of Lyonnet, who reared these larvae from the egg, would
-be of great interest. He says that he took about thirty larvae from
-the brood, and fed them with very small water-snails. These they
-devoured in the same way as the larger larvae do. Having seized the
-snail with their mandibles, they bent backwards, and supporting it
-on their back, which served them for a table, eat it there, without
-making any use of their legs to hold their prey. When the supply of
-small snails ran short, they did very well with large ones cut up into
-pieces, and with tadpoles. If, however, food was not supplied to them,
-they fed on each other. But, except when pressed by hunger, they lived
-together peaceably enough, and seemed to take pleasure in each other’s
-society[60].
-
-The larva of _Limnobia replicata_, a Crane-fly allied to, but
-smaller than, the well-known Daddy-longlegs, is another excellent
-subject for investigation. It is not very often taken; perhaps because
-it is not often looked for. But it is common enough, for all that.
-
-In general appearance these larvae resemble small caterpillars covered
-with spines. Some of these are simple and others forked, not much
-unlike the letter [image], with a short stem, and the arms slightly
-curved. There are no feet, and the last segment carries two pairs of
-hooks, one large and the other small. From their position they are
-called anal hooks.
-
-The dykes of the Sussex marshes are an excellent hunting-ground.
-Probably the channels of water-meadows, or any other shallow standing
-water in which aquatic moss grows, would serve the collector’s purpose
-quite as well. And such pieces of water abound all over the country.
-
-For taking these larvae the ordinary net and bottle are of little use,
-though a few may be captured by sweeping backwards and forwards among
-patches of aquatic moss.
-
-There is, however, a far easier and surer method. A good handful of
-the moss should be gathered, and put into a shallow vessel half full
-of water--a developing-dish answers capitally--and then shaken to and
-fro or gently stirred with a small piece of stick. The larvae will curl
-into a ring and fall to the bottom, whence they may be picked up and
-dropped into a bottle or other receptacle to be taken home. A fair
-quantity of moss should be gathered, for this is their favourite food,
-and all larvae are greedy feeders.
-
-Other water-plants, however, do not come amiss to them. Just before
-these lines were written I was examining a bottle in which some of
-these larvae were kept. It contained a few sprays of willow-moss and
-some ivy-leaved duckweed, which floated on the surface. One larva on a
-spray of moss was reaching upward, and it was distinctly seen to feed
-on the duckweed. This must have been from choice, for there was within
-reach plenty of what all observers consider to be its natural food.
-This, too, might have been more easily obtained; for, to reach the
-duckweed, the larva had to hold on to the moss by the anal hooks, and
-extend its body in a fashion analogous to that of the caterpillar of a
-geometer moth, which will hold on to a branch with its fore-legs and
-claspers and maintain the body at an angle of 45°, sometimes for hours
-together. I have also seen them feed on hornwort.
-
-The larva of this small Crane-fly is not at all difficult to keep. It
-is exceedingly hardy, and will survive a great deal of rough treatment.
-In November, 1895, I sent three in a tube--securely packed, as I
-thought--to a friend in Yorkshire. A few days afterwards I heard, with
-regret, ‘that the bottle was broken in transit, and that the larvae
-arrived dead.’ Three days later I was gratified by receiving a letter,
-from which the following is quoted: ‘The Limnobia larvae have come to
-life again. I put them into water as soon as they arrived, and after
-lying motionless for many hours they have begun to creep about and
-feed.’
-
-This is excellent testimony to their powers of endurance, but it is
-weak in comparison to that which De Geer supplies[61].
-
-He was Marshal of the Court of Sweden, and one November, before leaving
-his country house for his official duties at Stockholm, he put four
-of these larvae into a vessel of water, and left them to take their
-chance. The water froze into a solid mass. When he returned in the
-following May he found about half the water thawed, and two of the
-larvae dead. The others, though they had been enclosed in ice all the
-winter, were lively and in good condition. He put them into another
-vessel with fresh water and some aquatic moss, and at once they began
-to move about and commenced to feed. Both pupated by the fifteenth of
-the month, and the perfect fly emerged after six days in the pupal
-stage.
-
-  [Illustration: FIG. 78.--Larva of _Limnobia
-  replicata_.]
-
-The following description of this larva is principally condensed from
-De Geer, whence the figures are also taken. The body is long and
-cylindrical, and divided into eleven segments, of which the first and
-largest is sub-triangular. The second and third segments are shorter
-than the rest.
-
-The head (_t_) is very small and completely retractile within
-the first segment, the anterior margin of which completely closes
-the orifice, so that, in this condition, the creature appears to be
-headless. The body is covered with spines, some simple and others
-branched. On the first three segments there are only simple spines;
-but from the fourth to the tenth segment inclusive there are also on
-each segment two forked spines--that is, fourteen in all. On the last
-segment the spines are simple, and here are also four chitinous hooks,
-one pair much larger than the other. These simple spines carry a white
-vessel, which extends throughout their whole length; but in the forked
-spines there are two such vessels placed side by side in the stem, and
-diverging one to each branch.
-
-He comes to the conclusion that these spines are probably the breathing
-apparatus of the larva, for they are similar to those which he observed
-in an aquatic caterpillar. Walker[62] calls these spines ‘long
-filamentous processes, which appear to be internally supplied with
-air-tubes,’ but he does not seem to have taken the trouble to break up
-a specimen, or he would have been in no doubt as to their real nature.
-This is shown by the fact that the larva never comes to the surface to
-take in a supply of air, but contents itself with the oxygen dissolved
-in the water.
-
-  [Illustration:
-
-   FIG. 79.--Forked spine of Limnobia, enlarged; the dark
-   lines show air-tubes.]
-
-The pupa is quite as remarkable as the larva, though the breathing
-apparatus does not assume the form of spines, but consists of two
-‘trumpets,’ one on each side of the head, as is the case with the
-pupae of gnats, using that term in a wide sense. The colour is a
-greenish-brown, dotted with black. The abdomen is capable of a good
-deal of motion from side to side; and by this means the pupa can raise
-itself to the surface of the water to take in a supply of air.
-
-De Geer remarked that when the pupa rose for this purpose it lay with
-its body horizontal, having the lips of the trumpets a little above the
-surface. It appeared not to like being placed on its back, because in
-that position the trumpets cannot be raised above the surface. When he
-tried the experiment of putting the pupa back downwards, it wriggled
-over by bending the abdomen.
-
-  [Illustration: FIG. 80.--Pupa case of Limnobia.
-
-  (From a photograph taken at the Yorkshire College, Leeds.)]
-
-On the abdomen there are several chitinous hooks, which serve in some
-sort as substitutes for limbs. By their means the pupa can moor itself
-to the stems of aquatic plants; and this is necessary, since its
-specific gravity being less than that of the water it would be always
-at the surface, if it had no such means of anchorage. And of course,
-at the top of the water, it would be exposed to the danger of being
-snapped up by birds.
-
-De Geer’s specimen passed six days in the pupal state, and then emerged
-as a perfect Crane-fly. My specimens did not emerge till after ten and
-eleven days of pupahood, which seems strange, as they were plentifully
-supplied with food in their larval stage.
-
-The fly is a little more than half an inch long, and may be
-distinguished from the common Daddy-longlegs by the character of the
-wings, which are folded somewhat like those of a wasp, but with this
-difference: that the wings of this fly are folded outward, while those
-of the wasp are folded inwards. When the insect wishes to fly, it opens
-the fold so that the whole wing presents a plane surface, but the fold
-reappears directly the Crane-fly ceases its flight (Frontispiece).
-
-  [Illustration: FIG. 81.--Fore-wing of Bee, showing
-  marginal fold (× 7).]
-
-De Geer’s allusion to the wing of the wasp might have been extended
-to most of the Hymenoptera, as we may see by examining the fore and
-hind wings of a bee or a sawfly. Dr. Sharp[63] says, ‘The wings [of
-the Hymenoptera] are remarkable for the beautiful manner in which the
-hinder one is united to the anterior one, so that the two act in flight
-as a single organ. The hind wing is furnished with a series of hooks,
-and the hind margin of the front wing is curled over so that the hooks
-catch on to it. In some of the parasitic forms the wings ... have no
-hooks. The powers of flight, in these cases, are probably but small.’
-
-If we were taking our subjects in consecutive order, the larva of
-Ptychoptera would properly come here, as being that of a Crane-fly. But
-since it will be convenient to examine another larva which resemble
-Limnobia in its breathing apparatus, we will take next the larva of
-_Parap´onyx stratiota´ta_, one of the China Marks, for it is
-extremely interesting and by no means hard to come by.
-
-The China Marks are small moths, with white wings bearing dark
-markings, which have been supposed to resemble Chinese characters.
-Their larvae are aquatic in varying degree--that is, some breathe air
-in the usual way, by means of spiracles; while others, by means of
-gills, breathe the oxygen dissolved in the water.
-
-Many collectors have, no doubt, taken these larvae, and cast them away
-in the belief that they were caddis-worms. Such was the experience of
-the Rev. Gregory Bateman, the author of _Fresh-water Aquaria_,
-who says (p. 259): ‘While hunting for fresh-water animals, one not
-seldom comes across an insect wrapped up in two or more green leaves,
-or pieces of leaves, of some aquatic plant. The leaves and the animal
-have somewhat the appearance of a caddis-worm in its case; in fact, for
-a time, before I knew what it was, I mistook it (and I daresay others
-have done so also) for a caddis-worm.’
-
-The cases are usually, but not invariably, made from the food-plant
-of the insect. Mr. Bateman has noted that these larvae ‘do not
-always confine themselves to the same weed, either for food or for
-building material.’ This has also been my experience. A larva of the
-Brown China Mark, recently taken on the Norfolk Broads--an excellent
-collecting ground for aquatic larvae--was put into a tube. The case
-had been damaged, and the only vegetation in the tube was a spray of
-bladderwort. On examining the tube, after some days, I failed to find
-the larva. The reason was evident on removing the cork, a small part
-of which had been gnawed away to procure material for the repair of
-the larval case, which was affixed to the under side. The larva was
-dead and too much decayed to be put into pickle, a circumstance I much
-regret, as I should like to have preserved the larva in such a strange
-dwelling. As it is, I have only been able to keep the house without its
-tenant.
-
-Pondweed is the usual home of the larva of the Brown China Mark, and
-from the leaves of this plant the first larval case is generally
-fashioned. This was the species upon which Réaumur made his interesting
-observations, most of which have been confirmed by succeeding
-observers. In well-grown larvae the contrivance by which the animal
-is protected from contact with the water in which it lives should be
-noted, as it may be easily, with the hand lens. The skin is thickly set
-with tiny protuberances between which the water cannot penetrate, the
-surface film stretching from tip to tip of these prominences, just as
-it does over the hairs that cover the body of a water-spider.
-
-De Geer[64] describes an aquatic larva of one of the China Marks
-(_Paraponyx stratiotata_), which has its breathing apparatus
-fashioned on a similar plan to that of Limnobia, though there is some
-difference in the details. He found his specimens on the leaves of the
-Water Soldier, and his interesting account recalls the fact to memory
-that this remarkable plant was at one time called the Marsh Aloe--an
-exceedingly appropriate name.
-
-He describes the filaments on the body of the larva, and concluded
-that they were probably breathing-organs, because of the dark-coloured
-vessels within them. These he traced, as we will presently do, to their
-union in the stem of the gill, and thence to the air-vessels running
-down each side of the body of the larva. He fed them on leaves of the
-Water Soldier, and kept them through the winter. In the following June
-he found them preparing to undergo their transformation into the pupal
-stage, and at the end of the month the moths came out. He was gratified
-by seeing the congress of these insects. The females deposited their
-eggs on the floating vegetation and on the sides of his aquarium, a
-little below the surface of the water, and in about eight days the
-young larvae were seen.
-
-  [Illustration: FIG. 82.--Larva of _Paraponyx
-  stratiotata_ (enlarged).]
-
-These larvae must be very abundant, though they do not seem to be often
-taken by collectors. In describing an allied (American) species, which
-is found on Vallisneria and pondweed, Mr. Hart says[65], ‘They feed
-at first exposed on the leaf, but later two or even three leaves are
-loosely webbed together, face to face, by each larva, between which it
-remains concealed while feeding. They are, therefore, hard to discover
-unless their hiding-places are broken up by seining, or the like, when
-the larvae may be seen swimming about.’ This is, no doubt, the reason
-why these larvae are not more often taken. Anything like a seine net is
-of course out of the question for us; but masses of vegetation may be
-readily broken up by vigorously working the bottle and net backwards
-and forwards amongst them. Specimens I have seen were taken among
-duckweed; and Mr. Hart mentions one instance of part of the larval case
-being constructed of ivy-leaved duckweed, ‘which was abundant there at
-that time.’
-
-Now let us bring our lens to bear, so that we may make out the external
-structure, and recognize the similarity of the breathing-organs of this
-Moth-larva to those of the Crane-fly larva already treated of (p. 168).
-
-In order to make out the scheme of the gills, which is somewhat
-complicated, one should first of all distinguish the spiracles,
-remembering that they are not functional. And it is best to begin with
-those on the middle segments of the body. They may be detected as
-little dark spots, sometimes enclosed in a ring. The head, the first
-segment of the thorax, and the last segment of the body, bear no gills;
-the second segment of the thorax has but two pairs on each side; and
-there is but a single gill on each side of the ninth segment of the
-body. On the other (nine) body-segments there are the full number
-of five gills on each side, arranged two above, and three below the
-spiracle. The upper pair are called supra-stigmals, or gills which lie
-_above_ the spiracles; the lower pair are called infra-stigmals,
-or gills which lie _below_ the spiracles; and the single one, the
-lowest, is known as the pedal or foot gill. These technicalities need
-not give us any trouble here, in our examination of the larva; nor do
-they present any real difficulty. But it is worth while to master the
-arrangement as soon as we get hold of one of these larvae, and then we
-shall be able to take up and understand technical descriptions of this
-aquatic caterpillar and its allies, in so far, at least, as they refer
-to the breathing apparatus.
-
-The gills differ in their character: some few are simple, while most of
-them are more or less branched. In Limnobia the branching of the gills
-is into a simple fork; in Paraponyx this kind of division also occurs,
-and in others most of the gill branches are also given off from the
-main stem below one of the branches of the fork.
-
-In Fig. 84 we have a representation of one of these branched gills.
-It will not be difficult for us to make out the details as there
-shown. But the vessels that run down into the filaments, constituting
-them breathing-organs, are smaller than those of Limnobia, and will
-consequently require a little more care and patience before we can
-distinguish them.
-
-  [Illustration:
-
-    +---------------+
-    |  GILL    GILL |
-    |      SPIRACLE |
-    |  GILL    GILL |
-    |          GILL |
-    +---------------+
-
-   FIG. 83.--Diagram of segment of Paraponyx, showing
-   arrangements of tracheal gills.]
-
-  [Illustration:
-
-   FIG. 84.--Gill of Paraponyx larva. _a_, _b_,
-   stem; _c_, _d_, _e_, _f_, branches;
-   _g_, attachment of the air-vessel of the gill to the main
-   tracheae of the body. (After De Geer.)]
-
-One would think that, with such an array of gills, this larva ought
-to be in good case for its air-supply. It may, perhaps, be doubted
-whether this is so. At any rate, the creature adopts the same plan as
-the larva of Chironomus, which has no gills at all, for driving away
-from its case water that has parted with its oxygen. Water charged with
-oxygen pours into the case, and so the air-supply is renewed. This plan
-is nothing more than keeping the fore-part of the body in undulating
-motion, the tail in both the larvae serving as a point of attachment.
-One or two that I have kept made their cases against the side of the
-bottle, and so afforded an excellent opportunity of seeing them in this
-motion. The Tanypus larva does the same thing. Against the side of one
-of my small aquaria a Tanypus larva and a Chironomus larva have both
-made tubes; and as I look up from writing these lines I can see them
-both hard at this work.
-
-The larva of the Alder-fly (_Si´alis luta´rius_) is also furnished
-with tracheal gills, seven on each side. So little is known of the
-life-histories of common insects that it may be profitable to introduce
-the account of an observer who watched the deposition of the eggs and
-the emergence of the young larvae:
-
-‘On April 25 I found, on the rushes round the margin of a small pond,
-a great many patches of eggs, and shortly after observed many of the
-_Sialis lutarius_ depositing them.
-
-‘They form large patches of from two to three inches in length,
-generally encircling the whole rush near the top, but sometimes
-deposited on one side only, and extended to about a line in breadth.
-
-‘I counted 100 in a square line, so that each batch may be fairly
-considered to contain from 2,000 to 3,000 eggs; the greater portion of
-which must consequently perish either in the egg or larva state; as,
-common as the insect is, and widely distributed throughout the country,
-we should be perfectly overwhelmed with the swarms of the perfect
-insect if such were permitted, when it is considered that round this
-one small pond there could not have been less than 100 patches of them.
-
-‘The eggs are of a very singular form, and placed in a slanting
-position.
-
-‘The females, while depositing them, appeared perfectly motionless on
-the rush, and varied considerably in size, being from five lines to
-nearly double that in length. Some parts of the patches of eggs are of
-a much lighter colour than the rest.
-
-‘On May 3 I found many of the eggs hatching, the little larvae tumbling
-about in great numbers, with their bodies erected like [the larvae of]
-the _Staphylinidae_.
-
-‘On putting them into water they swam about with the greatest activity,
-wriggling and undulating their bodies about much like a serpent or the
-tadpoles, and working their legs at the same time[66].’
-
-The author draws attention to the disproportionately large head of the
-larvae, which, however, he did not describe, as he had ‘brought some of
-them alive, and some eggs for exhibition.’
-
-Sialis larvae occur in most ponds with muddy bottoms. They may be taken
-by scooping up some of the mud in a long-handled spoon--a most useful
-instrument for the collector--and washing it, or by throwing in the
-drag, and bringing to land a mass of water-weed, roots and all. A few
-may generally be detected near the roots. They may be picked up with a
-small pair of forceps, or with a brush, and dropped into a bottle; or,
-better still, into separate tubes; for they are fierce and voracious,
-and, failing other food, by no means indisposed to prey on each other.
-
-Their general appearance, and especially their powerful mandibles, give
-them some resemblance to the larvae of a water beetle, for which a
-celebrated naturalist not unnaturally took them, when he began to study
-them. And this would seem to be the opinion of some mounters, for I
-have a slide of the mouth parts of this larvae, labelled ‘Mouth parts
-of the larvae of a water beetle.’ It was not till I had broken up a
-good many Sialis larvae that I found out what the slide really was.
-
-These larvae may be kept alive in small bottles of water, if they
-are supplied with food. They will eat Chironomus larvae and those of
-Tanypus. Professor Miall has found that they will eat caddis-worms and
-May-fly larvae. Probably, no small aquatic creatures that they can
-overcome are safe from them.
-
-A larva that is full-fed, and ready to change to become a pupa, will
-measure about an inch in length or a little more (Fig. 85). The general
-colour is brownish, with dark markings. The legs are powerful, and our
-lens will show us that they end in two strong curved claws. From each
-of the first seven segments of the abdomen are given off a pair of
-jointed tracheal gills or breathing-organs, which are directed upwards
-and backwards when the larva is at rest--a rare occurrence--but which
-wave to and fro in the water when the creature is swimming.
-
-From this fact has arisen the statement found in most books that the
-larva uses these gills not only for respiration, but for locomotion.
-Professor Miall has come to a contrary conclusion, and, as he has
-kindly informed me, is confirmed in his opinion by the weakness of the
-muscles.
-
-  [Illustration:
-
-   FIG. 85.--Larva of Sialis (enlarged).]
-
-It will be well to make repeated observations till we are satisfied
-on the subject. When these larvae are kept, the conditions necessary
-to provide them with food and to keep the water aërated by means of
-growing vegetation are unfavourable to close observation. It will,
-therefore, be necessary to remove one or more of these larvae to a
-bottle in which there is nothing but pure water.
-
-The work is now rendered much easier. There is nothing to obstruct. As
-soon as the larvae reach the bottom they will walk round and round,
-giving us a good opportunity of watching them. In swimming--which may
-be backwards as well as forwards--the abdomen is waved from side to
-side. To see the backward motion one need only put a dipping-tube or a
-pencil, or the like, in front of the larva, so as to bar its progress.
-The creature will retreat a step or two, and then, with a flourish of
-the abdomen, dart back through the water. The larva will sometimes wave
-the abdomen up and down, just as one may see a Chironomus larva do when
-it has affixed its dwelling to the side of the glass, and this motion
-probably assists the process of respiration.
-
-When the larvae have been watched under the conditions above described,
-I have never been able to detect independent motion of the gills. But
-it is better that every one should observe for himself, and draw his
-own conclusions from what he sees.
-
-Now let us examine a specimen more closely with the lens, or under the
-dissecting microscope. The mouth parts may be broken up separately, or
-a little careful manipulation will enable us to see the chief features
-without injuring the specimen. The head is strong and massive, and
-the group of ocelli, or simple eyes, may be clearly made out. The
-antennae bear a small pencil of hairs, no doubt sensory in function,
-at the extremity, but careful management of the light will be required
-to distinguish them. The mandibles are extremely business-like
-instruments, and each bears two strong teeth on the inner side. Next
-come the maxillae, with their palps, each of which has an appendage,
-while each maxilla carries three strong spines. The labium, with its
-palps, and the mentum, with its saw-like notchings, may be plainly seen.
-
-The three segments of the thorax offer no difficulty. The legs are
-worth more than a cursory examination from their apparatus of spines
-and double fringe of hairs. Nine body-segments succeed to the thorax,
-and behind these is a long tail-like organ, which some authors consider
-represents a tenth segment.
-
-  [Illustration:
-
-    _h_  _t_  1  2  3  4  5  6  7  8  9    tail
-     -- ----- -- -- -- -- -- -- -- -- --  ------
-       |     |  |  |  |  |  |  |
-
-
-   FIG. 86.--Diagram of Sialis larva, showing arrangement
-   of gills (represented by vertical lines). _h_, head;
-   _t_, thorax; 1–9, segments of abdomen.]
-
-The gills are seven on each side, and are given off from the spaces
-in front of the first seven segments of the abdomen. Each gill is
-five-jointed--an unusual arrangement, for the gills of the larvae of
-Limnobia and Gyrinus are without joints. With the half-inch Leitz the
-branching tracheal tube in the gill may be seen, as well as the double
-fringe of hairs and the long hairs at the extremity. The tail-like
-organ, though without joints, bears a close resemblance to the gills.
-It has two tracheal tubes running through it, and it is fringed on both
-sides with hair. Indeed, Professor Miall, F.R.S., compares it to ‘two
-ordinary tracheal gills completely fused together.’ The first glance
-will convince the observer that the comparison is just.
-
-  [Illustration: FIG. 87.--Pupa of Sialis.]
-
-The pupa (Fig. 87) need not detain us, for the larva undergoes its
-transformation in the ground, not in the water, where it could be
-watched. But it is interesting to notice that the legs and wings are
-enclosed in separate cases, and that the segments of the abdomen bear
-spines. These spines are extremely serviceable to the pupa when making
-its way out of its cell to emerge as a perfect insect, which is well
-known, especially to fishermen, as the Alder-fly. It may be found near
-streams, and rarely uses its wings.
-
-_Ptychoptera paludosa_ is a small Crane-fly, with an aquatic larva
-which will repay observation. It is one of the group generally called
-‘rat-tailed maggots,’ from the peculiar character of the breathing
-apparatus, which consists of a retractile tube at the end of the
-abdomen. It is, I believe, better known to some dealers than the larva
-of the Drone-fly, the rat-tailed maggot of Réaumur. A few months ago I
-wanted some Drone-fly larvae, and asked a dealer to supply me. When the
-larvae arrived and were turned out for examination, they proved to be
-Ptychoptera larvae--which I did not want. I naturally wrote to point
-out the mistake; and was told, in reply, that the larvae sent were the
-only ‘rat-tails’ known to my correspondent.
-
-This larva is a mud-dweller, and is best captured by scooping up
-surface mud near the banks of pools and ditches, just where the water
-shallows on to the shore. This should be washed in a small dish or
-saucer, so as to carry away the mud and leave the larvae wriggling
-on the bottom. They may be picked up with a brush and dropped into a
-bottle for transport home.
-
-There is not the slightest difficulty about keeping them for
-observation. A bottle of the capacity of six or eight fluid ounces
-will make a good aquarium for a dozen or even twenty. The bottom should
-be covered to the depth of about an inch with mud fairly rich in
-organic matter. My own plan has been to use the accumulation from the
-bottom of a large aquarium. In this the larvae will bury the body, and
-feed, the tail protruding and thrust up to the surface of the water, of
-which there should be about two inches above the mud.
-
-This is a liberal allowance of space. A couple of these larvae lived
-with me for some months in a glass capsule two inches in diameter and
-three-quarters of an inch in height. The mud at the bottom and the
-water covering it together measured about half an inch. Both pupated,
-and in due time from the pupa cases a perfect insect came out.
-
-But that larvae may pupate, they require to be well fed. How shall
-we know when the bulk of the nourishment has been extracted from the
-mud? From the castings of the larvae; and these, though of a different
-shape, are as easy to be distinguished as the castings of the earthworm
-in the garden or those of the lobworm on the seashore. All the mud that
-passes through the bodies of the larvae is discharged in the form of
-tiny hard, cylindrical pellets; and when the mass consists of these
-pellets it should be changed, or the larvae will go short of food. They
-will, however, support long fasts.
-
-From Fig. 88 we may get a good idea of the appearance of the larvae
-when kept in confinement. The figures are rather less than natural
-size, and all the attitudes were sketched from life. One is seen
-extended on the bottom; two are partially buried in the mud, with the
-breathing-tube protruding. The larva on the mud, and bent into curves,
-is just about to rise to the surface; others are shown in the act of
-rising, while one has its breathing-tube raised above the surface, and
-another is attached by the breathing-tube to the side of the glass
-vessel. The larva with the star-like process at the end of the tail is
-that of Odontomyia, a large bee-like fly.
-
-  [Illustration: FIG. 88.--Larvae of _Ptychoptera
-  paludosa_ (from life).]
-
-A larva of good size, like that of Ptychoptera, is especially easy to
-examine; and by reason of its transparency the tracheal tubes may be
-clearly traced. The under surface of the larva should be first looked
-at, and its adaptation for existence in the mud of a pond-bottom will
-be evident. The creature is legless, but possesses three pairs of
-false legs armed with dark-coloured hooks, and each body-segment bears
-a circle of stiff hairs, which enable the larva to travel through
-the mud, in the same way that the earthworm moves through the soil.
-Moreover, the segments between these circles are pretty thickly set
-with hairs.
-
-The tracheal tubes run down on each side of the body, not in a direct
-line, for there is a most ingenious arrangement by which contraction
-and expansion of the larva, and the protrusion and retraction of
-the tail, are provided for. One can easily discern that in most of
-the segments the tubes are large, and that these large portions are
-connected by smaller tubes, whence others are given off into the body.
-These connecting-tubes are loop-like when the larva is of the normal
-length, but are straightened out, thus adding to their length, when the
-larva is extended.
-
-The opening and closing of these loops may be observed at leisure if
-a larva be put in a long excavated slip, with some water, and then
-covered with a plain glass slip. The two slips, fastened together with
-small elastic bands, should then be laid on the stage of the dissecting
-microscope for examination; or they may be held in the hands, and the
-movements of the larva watched with the hand lens.
-
-In the posterior segments of the body the tracheal tubes run side by
-side, while in the tail itself they are, so to speak, intertwined. When
-the tip of the tail pierces the surface-film a fresh supply of air is
-taken in.
-
-At the base of the extensile portion are two processes which diverge,
-one on each side, at an angle of 45 degrees. These, according to a
-German observer, are tracheal gills, and they are absorbed just before
-the larva enters the pupal condition.
-
-Réaumur found these larvae plentifully in the Bois de Boulogne, and
-gives a figure[67]. He was not, however, successful in rearing the fly.
-Lyonnet not only took the larvae and kept them in an aquarium, but
-watched their change into the pupal condition, and saw them emerge as
-perfect insects. An abstract of this description will probably be of
-interest.
-
-  [Illustration:
-
-   FIG. 89.--_A._ Ptychoptera larva (enlarged).
-   _B._ Tail, showing air-vessels (still more enlarged).
-   (After Lyonnet.)]
-
-He tells us that the larvae showed signs of changing into pupae in
-June. The change was made without the larvae leaving the water, and
-they underwent all their transformations in less than a fortnight.
-At the approach of the change the larvae became whiter in colour,
-but less transparent. Then they cast their skin, leaving therein the
-air-vessels, or rather their external covering. After this last moult
-was over, he was surprised to find that the tube which formed the tail
-of the larva, and by which it took in a supply of air, though it serves
-the same purpose in the pupa, is attached to the thorax, near the top
-of the head[68]. Lyonnet appears to have overlooked the fact that there
-was a second and shorter tube given off from the thorax, which most
-observers consider to be functionless (Fig. 90).
-
-  [Illustration: FIG. 90.--Pupa of Ptychoptera. (After
-  Lyonnet.)]
-
-Strange as is the larva, the pupa is stranger still, and seems even
-better adapted for existence in the mud. The hinder part of each
-segment of the abdomen is thickened and studded with chitinous
-projections. This thickening is more marked, and of greater extent in
-each succeeding segment, reaching its greatest development in the last
-segment, which is armed with hooks. The body part of each segment bears
-rows of smaller spines, so that this pupa should have little or no
-difficulty in moving through pretty thick mud.
-
-Several of these Crane-flies have passed through all their stages with
-me, and in nearly every case the transformation from pupa to perfect
-insect was made in water--in a tube three inches long, with a diameter
-of about an inch. The larvae were taken about the middle of September.
-My notes show that the first pupated on November 17, and the first fly
-came out on November 25.
-
-The long breathing-tube of the pupa was several times purposely
-displaced from its position on the surface. The creature was evidently
-incommoded, and twisted itself into strong curves; the head was thrown
-from side to side till part of the breathing-tube was raised above the
-surface and adhered to the side of the glass tube. Nor did the efforts
-cease till a considerable portion of the tube was in free communication
-with the air. This would seem to show that the air-supply is taken
-through the bladders which appear at irregular intervals in the
-breathing-tube, and not at the tip, where the keenest observers have
-failed to find an opening.
-
-
-
-
-                                 INDEX
-
-
-    Acridiidae, 80.
-
-    Alder-fly, larva of, 177;
-      pupa of, 182.
-
-    American Cockroach, 74.
-
-    Amphipods, 141;
-      Rev. T. R. R. Stebbing on, 141.
-
-    Aquaria, description of, 20.
-
-    Arachnoidea, 96.
-
-    _Argyroneta aquatica_, 108;
-      De Geer on, 109;
-      nest of, 110.
-
-    Arthropods, 27;
-      divisions of, 28;
-      description of, 29.
-
-    Ascidians, Darwin on, 13.
-
-    _Asellus aquaticus_, description of, 153.
-
-    Assassin Worm, 158.
-
-    Aurivillius, Dr., on Crabs, 150.
-
-
-    Bate and Westwood on Gammarus, 147;
-      on Talitrus, 151.
-
-    Bateman, Rev. G. C., on Hydrophilus, 50;
-      on Nepa, 91;
-      on China Marks, 171.
-
-    Beakers, 21.
-
-    Beetle Mite, 119.
-
-    Belt on Blatta, 67.
-
-    Black Beetle, 63.
-
-    Black-bobs, 64.
-
-    Blackwall on Spiders, 101, 102.
-
-    _Blatta orientalis_, description of, 63, 66;
-      Gilbert White on, 64;
-      Dr. Sharp on, 65;
-      Belt on, 67;
-      Sir J. Lubbock on, 68;
-      anatomy of, 68;
-      breathing of, 70;
-      Swammerdam on, 74;
-      Professor Plateau on, 74.
-
-    Book Scorpions, 96.
-
-    _Brachelytra_, 59.
-
-    Broad-clawed Porcelain Crab, 139.
-
-    Brown China Mark, 172.
-
-    Brushes, 23.
-
-    Bugs, 86.
-
-    Burgess, Mr., on larva of Dytiscus, 160.
-
-    Butler, Dr., on Spiders, 100.
-
-    Butler, Mr. E. A., on Forficula, 79.
-
-
-    Capsules, 21.
-
-    _Carcinus maenas_, description of, 136.
-
-    Centipedes, 122;
-      marine, 125.
-
-    Cerci, 47.
-
-    Chelate, meaning of word, 132 _n._
-
-    China Marks, 171;
-      Rev. G. C. Bateman on, 171;
-      De Geer on, 172.
-
-    Cockroach, 63.
-
-    Cocktail Beetle, 57.
-
-    Coleoptera, 32.
-
-    Collecting, method of, 25.
-
-    Corixa, 94;
-      Graber on, 95;
-      Sir J. Lubbock on, 95.
-
-    Crab, Shore, 136;
-      Porcelain, 139.
-
-    Crane-fly, 165.
-
-    Crustacea, 128.
-
-
-    Daddy-longlegs, 103.
-
-    Dallas on Ocypus, 61.
-
-    Darwin on microscopes, 12;
-      on Ascidians, 13.
-
-    Devil’s Coach Horse, 57.
-
-    Dipping-tubes, 23.
-
-    Dissecting microscope, 18.
-
-    Dissection, mode of, 37.
-
-    Diving Spiders, 108.
-
-    Dugès on Water Mites, 117.
-
-    Dung Beetle, 119.
-
-    _Dytiscus marginalis_, 31;
-      etymology of, 33 _n._;
-      breaking of shells by, 33;
-      Sowerby on, 34;
-      description of, 35;
-      food of, 36;
-      anatomy of, 37;
-      habits of, 41;
-      Kirby on, 41;
-      Sir J. Lubbock on, 42;
-      Professors Lowne and Miall on, 45;
-      Dr. Sharp on, 47;
-      abdomen of, 47;
-      breathing of, 48;
-      larva of, 157;
-      Swammerdam on, 158, 159;
-      Mr. Burgess on, 160.
-
-
-    Earwig, 75.
-
-    Edriophthalma, 129.
-
-    Elytra, 41.
-
-    _Epeira diadema_, description of, 98;
-      web of, 98;
-      J. A. Thomson on, 100;
-      Dr. Butler on, 100;
-      Blackwall on, 101, 102;
-      mode of taking its prey, 102;
-      Hudson on, 103;
-      feet of, 104;
-      spinnerets of, 105.
-
-    Evans, W., on Sialis, 177.
-
-
-    _Field_, the, quoted, 33, 35.
-
-    Forceps, 22.
-
-    _Forficula auricularia_, 75;
-      Kirby and Spence on, 76;
-      De Geer on, 76;
-      young of, 76;
-      forceps of, 77;
-      anatomy of, 77;
-      Butler on, 79;
-      Dr. Sharp on, 79.
-
-    Formalin, 24.
-
-    Forty-legs, 122.
-
-    Fresh-water Shrimp, 142.
-
-
-    _Gamasus coleoptratorum_, 119.
-
-    _Gammarus marinus_, 146;
-      Dr. J. Salter on, 147.
-
-    _Gammarus pulex_, 142;
-      anatomy of, 144.
-
-    Geer, De, on Forficula, 76;
-      on Locusta, 80;
-      on Water Mites, 116;
-      on Beetle Mites, 120;
-      on Lithobius, 123;
-      on Julus, 126;
-      on larva of Limnobia, 167;
-      on Paraponyx, 172.
-
-    Geophilus, 124.
-
-    _Geophilus crassipes_, 125;
-      Mr. Pocock on, 125.
-
-    Glass block, 22.
-
-    Glass box, 22.
-
-    Glass slips, 22.
-
-    Gosse on Prawns, 133.
-
-    Graber on Corixa, 95.
-
-    Grasshopper, Great Green, 80.
-
-    Great Water Beetle, 49.
-
-
-    Hart, Mr., on Paraponyx, 173.
-
-    Harvestmen, 96.
-
-    Hemiptera, 86.
-
-    Hill, Dr., on Nepa, 90.
-
-    Hudson on Spiders, 103.
-
-    Hundred-legs, 122.
-
-    Hunting Spiders, 98.
-
-    Hydrachna, 113.
-
-    _Hydrachna globula_, 118 _n._
-
-    Hydrophilus, larva of, 164;
-      Lyonnet on, 164.
-
-    _Hydrophilus piceus_, 49;
-      Bateman on, 50;
-      legs of, 53;
-      Simmermacher on, 53;
-      breathing of, 54;
-      cocoons of, 54;
-      Lyonnet on, 54.
-
-    Hymenoptera, wings of, 170.
-
-
-    Idotea, 143.
-
-    _Idotea pelagica_, 155.
-
-    Illinois State Laboratory, mode of collecting in, 25.
-
-    ‘Insects,’ 27;
-      divisions of, 32.
-
-    Invertebrates, 28.
-
-    Isopods, 152.
-
-
-    Julus, 121, 124.
-
-    _Julus terrestris_, 126;
-      De Geer on, 126;
-      Dr. Sharp on, 126.
-
-    Jumping Spiders, 105.
-
-
-    Kew, Mr., on dispersal of shells, 130.
-
-    Kirby on Dytiscus, 41;
-      on Ocypus, 59;
-      on Forficula, 76;
-      on Locusta, 83;
-      on insect noises, 84;
-      on Salticus, 107.
-
-    Knives, 24.
-
-
-    Land Bugs, 86.
-
-    Leaping Orthoptera, 79.
-
-    Leitz, lenses of, 16.
-
-    Lichtenstein on Locusta, 83.
-
-    Limnaea broken by Dytiscus, 33.
-
-    _Limnobia replicata_, larva of, 165;
-      De Geer on, 167;
-      pupa of, 168.
-
-    _Lithobius forficatus_, 122;
-      De Geer on, 123;
-      Dr. Sharp on, 123.
-
-    _Locusta viridissima_, 80;
-      Dr. Sharp on, 80, 85;
-      De Geer on, 80, 83;
-      Westwood on, 81;
-      Kirby on, 83;
-      Lichtenstein on, 83;
-      ear of, 85.
-
-    Locustidae, 80.
-
-    Lowne, Professor, on Dytiscus, 45.
-
-    Lubbock, Sir J., on Dytiscus, 42;
-      on Blatta, 68;
-      on Corixa, 95;
-      on Opossum Shrimp, 135.
-
-    Lyonnet on larva of Hydrophilus, 164;
-      on Ptychoptera, 186.
-
-
-    Magnification, power of, 15 _n._
-
-    Mainland, Mr. G. E., on Water Mites, 118.
-
-    Malacostraca, 128;
-      Rev. T. R. R. Stebbing on, 128.
-
-    Margined Water Beetle, 31.
-
-    Masking Crabs, 150.
-
-    _Melicerta janus_, 150.
-
-    Miall, Professor, on Dytiscus, 45;
-      on Sialis larvae, 179, 181.
-
-    Microscopes, use of, 11;
-      description of, 15.
-
-    Millepedes, 121, 125.
-
-    Mites, description of, 112.
-
-    Model, a calico, 30.
-
-    Myriapods, 96, 120.
-
-    Mysis, 135.
-
-
-    _Nature Notes_ on Millepedes, 121.
-
-    Needles, 23.
-
-    _Nepa cinerea_, 86;
-      mode of keeping, 88;
-      Swammerdam on, 89;
-      Dr. Hill on, 90;
-      Rev. G. C. Bateman on, 91;
-      anatomy of, 91.
-
-    Noises made by insects, 84.
-
-    _Notonecta glauca_, 93.
-
-
-    _Ocypus olens_, 57;
-      Kirby on, 59;
-      as a pet, 59;
-      Dallas on, 61;
-      larva of, 61.
-
-    Opossum Shrimp, 135;
-      Sir J. Lubbock on, 135.
-
-    _Orchestia littorea_, 151.
-
-    Orthoptera, 63.
-
-    Ovipositors, 82.
-
-
-    _Palaemon serratus_, 129.
-
-    _Palaemonetes varians_, 130.
-
-    _Paraponyx stratiotata_, 171;
-      De Geer on, 172;
-      Mr. Hart on, 173;
-      anatomy of, 174.
-
-    Peripatus, 30;
-      Professor Sedgwick on, 31.
-
-    _Periplaneta americana_, 74.
-
-    Pholcus, 103.
-
-    Phylum, definition of, 27.
-
-    Planorbis broken by Dytiscus, 33.
-
-    Plateau, Professor, on Blatta, 74.
-
-    Pocket lens, description of, 13.
-
-    Pocock, Mr., on Geophilus, 125.
-
-    Podophthalma, 129.
-
-    _Porcellana platycheles_, 139.
-
-    Prawns, 129;
-      Gosse on, 133;
-      Sowerby on, 133.
-
-    Ptychoptera, larva of, 182;
-      pupa of, 187;
-      Réaumur on, 185;
-      Lyonnet on, 186.
-
-
-    Quekett Microscopical Club, incident at, 20.
-
-
-    ‘Rat-tails,’ 182.
-
-    Réaumur on Ptychoptera, 185.
-
-    Robertson, Mr., on Talitrus, 151.
-
-
-    Salter, Dr. J., on Gammarus, 147.
-
-    _Salticus scenicus_, 105;
-      Kirby and Spence on, 107;
-      foot of, 108.
-
-    Sand-hopper, 151.
-
-    Scorpions, 96.
-
-    Sedgwick, Professor, on Peripatus, 31.
-
-    Sharp, Dr., on Dytiscus, 47;
-      on Blatta, 65;
-      on Forficula, 79;
-      on Locusta, 80, 85;
-      on Lithobius, 123;
-      on Julus, 126;
-      on wings of Hymenoptera, 170.
-
-    Shells broken by Dytiscus, 33;
-      Mr. Kew on dispersal of, 130.
-
-    Shore Crab, 136.
-
-    Shore-hopper, 151.
-
-    Shrimp, 132.
-
-    _Sialis lutarius_, larva of, 177;
-      W. Evans on, 177;
-      anatomy of, 180;
-      pupa of, 182.
-
-    Sicarius, 158.
-
-    Simmermacher on Hydrophilus, 53.
-
-    Sirex, 82.
-
-    Sowerby, G. B., on Dytiscus, 34.
-
-    Sphaerium, 130.
-
-    Sphaeroma, 155.
-
-    Spiders, general description of, 96;
-      Trap-door, 97;
-      Hunting, 98;
-      Garden, 98;
-      Jumping, 105;
-      Diving, 108.
-
-    Stebbing, Rev. T. R. R., on etymology of Dytiscus, 33 _n._;
-      on Malacostraca, 128;
-      on meaning of _chelate_ and _sub-chelate_, 132 _n._;
-      on Amphipods, 141.
-
-    Stewart, Professor, incident of, 20.
-
-    Stilopyga, 63.
-
-    Swammerdam on Blatta, 74;
-      on Nepa, 89;
-      on Water Mites, 114;
-      on Woodlice, 156;
-      on Dytiscus larva, 158, 159.
-
-
-    Tailed Wasp, 82.
-
-    _Talitrus locusta_, 151;
-      Bate and Westwood on, 151;
-      Mr. Robertson on, 152.
-
-    Tanypus, larva of, 176.
-
-    Tegetmeier, Mr. W. B., on destruction of shells, 34.
-
-    Thomson, J. A., on Spiders, 100.
-
-    Trap-door Spider, 97.
-
-
-    Vertebrates, 28.
-
-
-    Wart-eater, 81.
-
-    Water Beetle, Margined, 31;
-      the Great, 49.
-
-    Water Boatman, 93.
-
-    Water Bugs, 86.
-
-    Water-devil, 157.
-
-    Water Mites, 113;
-      Swammerdam on, 114;
-      De Geer on, 116;
-      Dugès on, 117;
-      Mainland on, 118.
-
-    Water Scorpion, 86.
-
-    Water-tiger, 157.
-
-    Westwood on Locusta, 81.
-
-    White, Gilbert, on Blatta, 64.
-
-    Wing-cases, 41.
-
-    Wireworm, 126.
-
-    Wood, Rev. J. G., on lens stand, 15.
-
-    Woodlice, 155;
-      Swammerdam on, 156.
-
-    Worms, 29.
-
-    Wright, Mr. L., on microscopes, 16.
-
-
-    Zeiss, lenses of, 15.
-
-
-                               THE END.
-
-
-FOOTNOTES:
-
-[1] Darwin, _Descent of Man_ (2nd ed.), p. 159, note 23.
-
-[2] The power of magnification of a lens is the ratio of its focal
-distance to 10 inches. Thus a lens of 1 inch focus (or focal distance)
-magnifies 10 times (written × 10, or ten diameters); one of ½ in. focal
-distance, 20 times, and so on.
-
-[3] _A Popular Handbook to the Microscope_, p. 39.
-
-[4] _Journal of the Quekett Microscopical Club_, v. 148.
-
-[5] _Ponds and Rock Pools_, p. 17.
-
-[6] _Bulletin of the Illinois State Laboratory of Natural
-History_, iv. 158.
-
-[7] ‘Dytiscus’ is written of set purpose. It is not, as some people
-tell us, a miswriting for Dyticus; but a properly formed diminutive,
-from the Greek _dutēs_ = a diver; like _paidiskos_ = a little boy.
-Linnaeus consistently calls the genus Dytiscus from 1735 onwards.
-Dyticus only dates from Geoffroy’s _Histoire Abrégée des Insectes_,
-first published anonymously in 1762. On this question of nomenclature I
-am glad to have the support of the Rev. T. R. R. Stebbing, F.R.S., who,
-in answer to my inquiries, kindly wrote, ‘Darwin uses “Dytiscus” in the
-_Origin of Species_, and I should decidedly recommend its being upheld.’
-
-[8] April 4, 1896.
-
-[9] _Popular History of the Aquarium_, p. 258.
-
-[10] May 2, 1896.
-
-[11] International Science Series, No. lxv.
-
-[12] _Aquatic Insects_, pp. 55, 56.
-
-[13] _Zeitschrift f. wiss. Zoologie_, Bd. xl. S. 481.
-
-[14] _Mémoires du Muséum d’histoire naturelle_, xviii. 454 sqq.
-
-[15] I have purposely given _Blatta_ as the generic name, rather
-than _Stilopyga_, which should properly be used, as the former is
-only employed in very recent literature.
-
-[16] Miall and Denny, _The Cockroach_, p. 20.
-
-[17] _Cambridge Natural History_, v. 231.
-
-[18] _The Senses of Animals_, p. 44.
-
-[19] _Cambridge Nat. Hist._ v. 223.
-
-[20] _Book of Nature_, p. 94.
-
-[21] This refers to the gizzard. _Echinus_ was used to denote the
-third stomach of Ruminants (now called the manyplies), because it was
-thought to resemble a hedgehog rolled up.
-
-[22] Miall and Denny, _The Cockroach_, p. 118 (note).
-
-[23] _Introduction to Entomology_, letter xi.
-
-[24] _Proceedings of the Zoological Society_, 1892, p. 586.
-
-[25] _Our Household Insects_, pp. 159–163.
-
-[26] Kirby and Spence, _Introd. to Entomology_, ed. 1870, p. 484.
-
-[27] _Cambridge Natural History_, v. 318.
-
-[28] _The Senses of Animals_, p. 75.
-
-[29] J. Arthur Thomson, _Outlines of Zoology_, p. 288.
-
-[30] _Science for All_, ii. 178.
-
-[31] _British Spiders_, p. 10.
-
-[32] _British Spiders_, p. 359.
-
-[33] _Naturalist in La Plata_, p. 188.
-
-[34] _Mémoires_, vii. p. 304 sqq.
-
-[35] _Book of Nature_, pp. 101, 102.
-
-[36] _Mémoires_, vii. 144, 145.
-
-[37] The specimen was kindly identified for me, by Dr. Trouessart of
-Paris, as a nymph of _Hydrachna globula_ (Dugès), and has been
-deposited in the British Museum (Natural History).
-
-[38] _Mémoires_, vii. 123–128.
-
-[39] _Cambridge Natural History_, vol. v. ch. ii.
-
-[40] _Nature_, Dec. 12, 1895.
-
-[41] _Mémoires_, vii. 569.
-
-[42] _Crustacea_, p. 7.
-
-[43] _Crustacea_, p. 225.
-
-[44] International Science Series, No. lxxv.
-
-[45] ‘A limb is _chelate_ when it has joints that will act
-together like a pair of tongs. Generally this character is produced by
-the hinging of the seventh joint a considerable way down on the side
-of the sixth. When the seventh joint, or finger, can be folded back
-upon the sixth, although the latter is not produced into any thumb-like
-process to oppose it, the limb is then said to be _sub-chelate_,
-the claw being in that case partial, though often extremely efficient.’
-Stebbing, _Crustacea_ (International Science Series, lxxiv), p. 45.
-
-[46] _Popular History of the Aquarium_, p. 223.
-
-[47] Lubbock, _Senses of Animals_ (International Science Series,
-lxv.), p. 93.
-
-[48] _Aquarium_ (ed. 1856), pp. 41, 42.
-
-[49] _Crustacea_ (International Science Series, lxxiv), pp. 8, 9.
-
-[50] Bate and Westwood, _British Sessile-eyed Crustacea_, i. 8.
-
-[51] _Trans. Connecticut Academy_ (1882), iv. 274, 275, note.
-
-[52] _Ponds and Rock Pools_, p. 118.
-
-[53] _British Sessile-eyed Crustacea_, i. 21.
-
-[54] _Proceedings Nat. Hist. Soc. Glasgow_, vol. i. pt. ii. n. s.
-pp. 130–132.
-
-[55] _British Sessile-eyed Crustacea_, ii. 381.
-
-[56] _Book of Nature_, i. 174.
-
-[57] _Mémoires_, iv. 386.
-
-[58] _Proceedings Boston Society of Natural History_, xxi. 223–228.
-
-[59] _Natural History of Aquatic Insects_, p. 47.
-
-[60] _Mémoires du Museum_, xviii. 442, 443.
-
-[61] _Mémoires_, vi. 352–55.
-
-[62] _Diptera_, iii. 281.
-
-[63] _Cambridge Natural History_, v. 494.
-
-[64] _Mémoires pour servir_, i. 577 sqq.
-
-[65] _Bulletin of the Illinois State Laboratory of Natural
-History_, iv. 167.
-
-[66] W. Evans, _Trans. Entomol. Soc._ (London), iv. 261.
-
-[67] _Mémoires pour servir_, t. vi. Plate 31.
-
-[68] _Mémoires du Muséum_, t. xix. pp. 103, 104.
-
-
-Transcriber’s Notes:
-
- 1. Obvious printers’, punctuation and spelling errors have been
-    corrected silently.
-
- 2. Some hyphenated and non-hyphenated versions of the same words have
-    been retained as in the original.
-
- 3. Superscripts are represented using the caret character, e.g. D^r.
-    or X^{xx}.
-
- 4. Italics are shown as _xxx_.
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-<body>
-<p style='text-align:center; font-size:1.2em; font-weight:bold'>The Project Gutenberg eBook of Through a pocket lens, by Henry Scherren</p>
-<div style='display:block; margin:1em 0'>
-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 <a href="https://www.gutenberg.org">www.gutenberg.org</a>. If you
-are not located in the United States, you will have to check the laws of the
-country where you are located before using this eBook.
-</div>
-
-<p style='display:block; margin-top:1em; margin-bottom:1em; margin-left:2em; text-indent:-2em'>Title: Through a pocket lens</p>
-<p style='display:block; margin-top:1em; margin-bottom:0; margin-left:2em; text-indent:-2em'>Author: Henry Scherren</p>
-<p style='display:block; text-indent:0; margin:1em 0'>Release Date: September 13, 2022 [eBook #68981]</p>
-<p style='display:block; text-indent:0; margin:1em 0'>Language: English</p>
-  <p style='display:block; margin-top:1em; margin-bottom:0; margin-left:2em; text-indent:-2em; text-align:left'>Produced by: deaurider, Karin Spence and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive)</p>
-<div style='margin-top:2em; margin-bottom:4em'>*** START OF THE PROJECT GUTENBERG EBOOK THROUGH A POCKET LENS ***</div>
-
-  <div class="figcenter" id="i_002" style="width: 650px">
-     <img
-    class="p2"
-    src="images/i_002.jpg"
-     alt="" />
-     <p class="p0 sm center">PTYCHOPTERA PALUDOSA<span style="margin-left: 3em">LIMNOBIA REPLICATA</span></p>
-     <p class="p0 sm center"><i>From enlarged photographs, made at the Yorkshire College, Leeds,
-from specimens bred by the Author, and mounted by Messrs. Watson &amp; Son,
-High Holborn, London</i></p>
-  </div>
-
-
-<h1>THROUGH<br />
-A POCKET LENS</h1>
-
-<p class="center xs p4">BY</p>
-
-<p class="center p2">HENRY SCHERREN, F.Z.S.</p>
-
-<p class="center xs">AUTHOR OF<br />
-‘PONDS AND ROCK POOLS,’ ‘A POPULAR HISTORY OF ANIMALS,’ ETC.</p>
-
-
-<p class="center p4"><i>WITH NINETY ILLUSTRATIONS</i></p>
-
-
-<p class="center sm p6">THE RELIGIOUS TRACT SOCIETY</p>
-
-<p class="center xs">56 PATERNOSTER ROW AND 65 ST. PAUL’S CHURCHYARD</p>
-
-<p class="center sm">1897</p>
-
-<p class="center p6 sm"><b>Oxford</b></p>
-
-<p class="center xs">HORACE HART, PRINTER TO THE UNIVERSITY</p>
-
-
-<div class="chapter">
-<h2 class="smaller">CONTENTS</h2>
-</div>
-
-  <div class="figcenter" id="line">
-    <img
-    class="p0"
-    src="images/line.jpg"
-    alt="" />
-  </div>
-
-
-<table summary="contents" class="smaller" style="max-width: 30em">
-  <tr>
-    <th class="pag">PAGE</th>
-    <th></th>
-  </tr>
-
-  <tr>
-    <td class="header" colspan="2">CHAPTER I.</td>
-  </tr>
-
-  <tr>
-    <td class="cht1">The Pocket Lens, the Dissecting Microscope, and
-some simple Appliances</td>
-    <td class="pag"><a href="#Page_11">11</a></td>
-  </tr>
-
-  <tr>
-    <td class="header" colspan="2">CHAPTER II.</td>
-  </tr>
-
-  <tr>
-    <td class="cht1">Arthropods and their Classes.&mdash;The Margined
-Water Beetle; the Great Water Beetle; the
-Cocktail Beetle</td>
-    <td class="pag"><a href="#Page_27">27</a></td>
-  </tr>
-
-  <tr>
-    <td class="header" colspan="2">CHAPTER III.</td>
-  </tr>
-
-  <tr>
-    <td class="cht1">Cockroaches; Earwigs; the Great Green Grasshopper;
-the Water Scorpion; the Water Boatman; Corixa</td>
-    <td class="pag"><a href="#Page_63">63</a></td>
-  </tr>
-
-  <tr>
-    <td class="header" colspan="2">CHAPTER IV.</td>
-  </tr>
-
-  <tr>
-    <td class="cht1">Spiders, Mites, and Myriapods</td>
-    <td class="pag"><a href="#Page_96">96</a></td>
-  </tr>
-
-  <tr>
-    <td class="header" colspan="2">CHAPTER V.</td>
-  </tr>
-
-  <tr>
-    <td class="cht1">Crustaceans.&mdash;Prawn, Shrimp, Mysis, Crabs; Amphipods; Isopods</td>
-    <td class="pag"><a href="#Page_128">128</a></td>
-  </tr>
-
-  <tr>
-    <td class="header" colspan="2">CHAPTER VI.</td>
-  </tr>
-
-  <tr>
-    <td class="cht1">Aquatic Insect Larvae</td>
-    <td class="pag"><a href="#Page_157">157</a></td>
-  </tr>
-
-  <tr>
-    <td class="cht1">Index</td>
-    <td class="pag"><a href="#Page_189">189</a></td>
-  </tr>
-
-</table>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_7">[7]</span></p>
-
-<h2>LIST OF ILLUSTRATIONS</h2>
-</div>
-
-<table summary="illos" class="smaller" style="max-width: 50em">
-  <tr>
-    <th class="chap">FIG.</th>
-    <th></th>
-    <th class="pag">PAGE</th>
-  </tr>
-
-  <tr>
-    <td class="chn"></td>
-    <td class="cht"><i>Ptychoptera paludosa. Limnobia replicata</i></td>
-    <td class="pag"><a href="#i_002"><i>Frontispiece</i></a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">1.</td>
-    <td class="cht">Hand Magnifier and Stand</td>
-    <td class="pag"><a href="#i_014">14</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">2.</td>
-    <td class="cht">Zeiss’s Dissecting Microscope</td>
-    <td class="pag"><a href="#i_016">16</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">3.</td>
-    <td class="cht">Leitz’s Dissecting Microscope</td>
-    <td class="pag"><a href="#i_017">17</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">4.</td>
-    <td class="cht">Two Leitz Lenses in holder (open)</td>
-    <td class="pag"><a href="#i_018a">18</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">5.</td>
-    <td class="cht">Two Leitz Lenses in holder (closed)</td>
-    <td class="pag"><a href="#i_018b">18</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">6.</td>
-    <td class="cht">Home-made Dissecting Microscope</td>
-    <td class="pag"><a href="#i_019">19</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">7.</td>
-    <td class="cht">Beakers</td>
-    <td class="pag"><a href="#i_021a">21</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">8.</td>
-    <td class="cht">Glass Capsule</td>
-    <td class="pag"><a href="#i_021b">21</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">9.</td>
-    <td class="cht">Glass Block, with cover</td>
-    <td class="pag"><a href="#i_022a">22</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">10.</td>
-    <td class="cht">Glass Box, with cover</td>
-    <td class="pag"><a href="#i_022b">22</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">11.</td>
-    <td class="cht">Forceps</td>
-    <td class="pag"><a href="#i_023">23</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">12.</td>
-    <td class="cht">Three forms of Dipping-tube. Method of using it</td>
-    <td class="pag"><a href="#i_024">24</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">13.</td>
-    <td class="cht">Mounted Needles</td>
-    <td class="pag"><a href="#i_025">25</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">14.</td>
-    <td class="cht">Cape Peripatus (natural size)</td>
-    <td class="pag"><a href="#i_030">30</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">15.</td>
-    <td class="cht">Margined Water Beetle (male)</td>
-    <td class="pag"><a href="#i_032">32</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">16.</td>
-    <td class="cht">Shells of Molluscs broken up by Dytiscus</td>
-    <td class="pag"><a href="#i_033">33</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">17.</td>
-    <td class="cht">Outline of Dytiscus</td>
-    <td class="pag"><a href="#i_038">38</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">18.</td>
-    <td class="cht">Male Dytiscus in flight</td>
-    <td class="pag"><a href="#i_039">39</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">19.</td>
-    <td class="cht">To show fold of (right) wing of Dytiscus</td>
-    <td class="pag"><a href="#i_040a">40</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">20.</td>
-    <td class="cht">To show fold of (right) wing of Dytiscus</td>
-    <td class="pag"><a href="#i_040b">40</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">21 and 21 <span class="allsmcap">A</span>.</td>
-    <td class="cht">Head of Dytiscus</td>
-    <td class="pag"><a href="#i_042a">42</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">22.</td>
-    <td class="cht">Disposition of mouth parts</td>
-    <td class="pag"><a href="#i_043">43</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">23.</td>
-    <td class="cht">Leg of Cockroach</td>
-    <td class="pag"><a href="#i_044">44</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">24.</td>
-    <td class="cht">Tarsus of Dytiscus (magnified)</td>
-    <td class="pag"><a href="#i_045">45</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">25.</td>
-    <td class="cht">Female Dytiscus swimming</td>
-    <td class="pag"><a href="#i_046">46</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">26.</td>
-    <td class="cht">Upper surface of abdomen of typical Beetle</td>
-    <td class="pag"><a href="#i_047">47</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">27.</td>
-    <td class="cht">Spiracle of Dytiscus (magnified)</td>
-    <td class="pag"><a href="#i_048a">48</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">28.</td>
-    <td class="cht">Tracheal tubes of Dytiscus (magnified)</td>
-    <td class="pag"><a href="#i_048b">48</a><span class="pagenum" id="Page_8">[8]</span></td>
-  </tr>
-
-  <tr>
-    <td class="chn">29.</td>
-    <td class="cht">Great Water Beetle</td>
-    <td class="pag"><a href="#i_051">51</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">30.</td>
-    <td class="cht">Female Hydrophilus constructing a cocoon. (After Lyonnet)</td>
-    <td class="pag"><a href="#i_055">55</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">31.</td>
-    <td class="cht">Cocktail Beetle</td>
-    <td class="pag"><a href="#i_058">58</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">32.</td>
-    <td class="cht">Cockroaches</td>
-    <td class="pag"><a href="#i_066">66</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">33.</td>
-    <td class="cht">Mouth parts of a Cockroach</td>
-    <td class="pag"><a href="#i_069">69</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">34.</td>
-    <td class="cht">Cockroach, showing Spiracles</td>
-    <td class="pag"><a href="#i_071">71</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">35.</td>
-    <td class="cht">Alimentary Canal of Cockroach</td>
-    <td class="pag"><a href="#i_073">73</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">36.</td>
-    <td class="cht">American Cockroach (male)</td>
-    <td class="pag"><a href="#i_075">75</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">37.</td>
-    <td class="cht">Larva and Pupa of Earwig</td>
-    <td class="pag"><a href="#i_077">77</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">38.</td>
-    <td class="cht">Earwig (male)</td>
-    <td class="pag"><a href="#i_078">78</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">39.</td>
-    <td class="cht">Great Green Grasshopper (female)</td>
-    <td class="pag"><a href="#i_081">81</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">40.</td>
-    <td class="cht">Tibial ear of Great Green Grasshopper</td>
-    <td class="pag"><a href="#i_085">85</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">41.</td>
-    <td class="cht">Land Bug (magnified)</td>
-    <td class="pag"><a href="#i_086">86</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">42.</td>
-    <td class="cht">Water Scorpion</td>
-    <td class="pag"><a href="#i_087">87</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">43.</td>
-    <td class="cht">Organs of Water Scorpion, Egg, and Parasitic Mite. (After Swammerdam)</td>
-    <td class="pag"><a href="#i_090">90</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">44.</td>
-    <td class="cht">Raptorial leg of Water Scorpion</td>
-    <td class="pag"><a href="#i_092">92</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">45.</td>
-    <td class="cht">Water Boatman</td>
-    <td class="pag"><a href="#i_093">93</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">46.</td>
-    <td class="cht">Water Boatman swimming</td>
-    <td class="pag"><a href="#i_094">94</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">47.</td>
-    <td class="cht">Corixa, with wings expanded</td>
-    <td class="pag"><a href="#i_095">95</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">48.</td>
-    <td class="cht">Scheme of under surface of Wolf Spider (female). Pedipalp of male (enlarged)</td>
-    <td class="pag"><a href="#i_098">98</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">49.</td>
-    <td class="cht">Garden Spider and Web</td>
-    <td class="pag"><a href="#i_099">99</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">50.</td>
-    <td class="cht">Threads of Spider’s Web</td>
-    <td class="pag"><a href="#i_100">100</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">51.</td>
-    <td class="cht">Anchorage of Web</td>
-    <td class="pag"><a href="#i_101">101</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">52.</td>
-    <td class="cht">Foot of Garden Spider</td>
-    <td class="pag"><a href="#i_104a">104</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">53.</td>
-    <td class="cht">Spinnerets of Garden Spider</td>
-    <td class="pag"><a href="#i_104b">104</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">54.</td>
-    <td class="cht">Jumping Spider</td>
-    <td class="pag"><a href="#i_106a">106</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">55.</td>
-    <td class="cht">Falces of Male Jumping Spider</td>
-    <td class="pag"><a href="#i_106b">106</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">56.</td>
-    <td class="cht">Foot of Jumping Spider. Scopula much enlarged</td>
-    <td class="pag"><a href="#i_108">108</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">57.</td>
-    <td class="cht">Diving Spiders</td>
-    <td class="pag"><a href="#i_109">109</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">58.</td>
-    <td class="cht">Cell of Diving Spider</td>
-    <td class="pag"><a href="#i_112">112</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">59.</td>
-    <td class="cht">Red Water Mite</td>
-    <td class="pag"><a href="#i_114">114</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">60.</td>
-    <td class="cht">Larva of Water Mite</td>
-    <td class="pag"><a href="#i_117a">117</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">61.</td>
-    <td class="cht">Nymph of Water Mite</td>
-    <td class="pag"><a href="#i_117b">117</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">62.</td>
-    <td class="cht">Beetle Mite</td>
-    <td class="pag"><a href="#i_119">119</a><span class="pagenum" id="Page_9">[9]</span></td>
-  </tr>
-
-  <tr>
-    <td class="chn">63.</td>
-    <td class="cht"><i>Lithobius forficatus.</i> Mouth parts seen from below. (After Graber)</td>
-    <td class="pag"><a href="#i_124">124</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">64.</td>
-    <td class="cht">The Common Millepede</td>
-    <td class="pag"><a href="#i_126">126</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">65.</td>
-    <td class="cht">Segments of Millepede (magnified)</td>
-    <td class="pag"><a href="#i_127">127</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">66.</td>
-    <td class="cht">Prawn</td>
-    <td class="pag"><a href="#i_132">132</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">67.</td>
-    <td class="cht">First walking leg of Shrimp (enlarged)</td>
-    <td class="pag"><a href="#i_134">134</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">68.</td>
-    <td class="cht">Mysis, or the Opossum Shrimp</td>
-    <td class="pag"><a href="#i_135">135</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">69.</td>
-    <td class="cht">Maxillipedes and Maxilla of Shore Crab. (After Savigny)</td>
-    <td class="pag"><a href="#i_138">138</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">70.</td>
-    <td class="cht">Stomach of Crab laid open</td>
-    <td class="pag"><a href="#i_139">139</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">71.</td>
-    <td class="cht">Gammarus. (After Sars)</td>
-    <td class="pag"><a href="#i_142">142</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">72.</td>
-    <td class="cht">Maxillipedes of <i>Gammarus marinus</i> (magnified)</td>
-    <td class="pag"><a href="#i_146">146</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">73.</td>
-    <td class="cht">Nest-building Amphipod (from life)</td>
-    <td class="pag"><a href="#i_148">148</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">74.</td>
-    <td class="cht">Water Woodlouse</td>
-    <td class="pag"><a href="#i_153">153</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">75.</td>
-    <td class="cht">Mouth-lock. (After Burgess)</td>
-    <td class="pag"><a href="#i_161">161</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">76.</td>
-    <td class="cht">Dytiscus Larvae</td>
-    <td class="pag"><a href="#i_162">162</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">77.</td>
-    <td class="cht">Pupa of Dytiscus</td>
-    <td class="pag"><a href="#i_164">164</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">78.</td>
-    <td class="cht">Larva of <i>Limnobia replicata</i></td>
-    <td class="pag"><a href="#i_167">167</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">79.</td>
-    <td class="cht">Forked spine of Limnobia (enlarged)</td>
-    <td class="pag"><a href="#i_168">168</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">80.</td>
-    <td class="cht">Pupa case of Limnobia</td>
-    <td class="pag"><a href="#i_169">169</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">81.</td>
-    <td class="cht">Fore wing of Bee, showing marginal fold (×7)</td>
-    <td class="pag"><a href="#i_170">170</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">82.</td>
-    <td class="cht">Larva of <i>Paraponyx stratiotata</i> (enlarged)</td>
-    <td class="pag"><a href="#i_173">173</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">83.</td>
-    <td class="cht">Diagram of segment of Paraponyx, showing arrangement of tracheal gills</td>
-    <td class="pag"><a href="#i_175">175</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">84.</td>
-    <td class="cht">Gill of Paraponyx larva. (After De Geer)</td>
-    <td class="pag"><a href="#i_176">176</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">85.</td>
-    <td class="cht">Larva of Sialis (enlarged)</td>
-    <td class="pag"><a href="#i_179">179</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">86.</td>
-    <td class="cht">Diagram of Sialis larva, showing arrangement of gills</td>
-    <td class="pag"><a href="#i_181a">181</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">87.</td>
-    <td class="cht">Pupa of Sialis</td>
-    <td class="pag"><a href="#i_181b">181</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">88.</td>
-    <td class="cht">Larvae of <i>Ptychoptera paludosa</i> (from life)</td>
-    <td class="pag"><a href="#i_184">184</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">89.</td>
-    <td class="cht">Ptychoptera Larva (enlarged). Tail. (After Lyonnet)</td>
-    <td class="pag"><a href="#i_186">186</a></td>
-  </tr>
-
-  <tr>
-    <td class="chn">90.</td>
-    <td class="cht">Pupa of Ptychoptera. (After Lyonnet)</td>
-    <td class="pag"><a href="#i_187">187</a></td>
-  </tr>
-</table>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_11">[11]</span></p>
-
-<p class="center xl">THROUGH A POCKET LENS</p>
-</div>
-
-<h2>CHAPTER I<br />
-<span class="subhed">THE POCKET LENS, THE DISSECTING MICROSCOPE, AND SOME SIMPLE APPLIANCES</span></h2>
-
-<div>
-<img class="drop-cap" src="images/i_011.jpg" width="51" alt="" />
-</div>
-
-<p class="drop-cap p-left">The object of this little book is to show how much may be seen
-with an ordinary pocket lens, and with a simple microscope; and,
-as far as possible, to dispel the idea, far too common, especially
-among beginners, that no real work can be done unless one has a
-compound microscope, with a large battery of lenses and an array of
-‘accessories.’</p>
-
-<p>It would be easy to multiply quotations, from high authorities, in
-support of the proposition implied in the foregoing paragraph. Two only
-must suffice.</p>
-
-<p>In a recent review of a very good book dealing with Butterflies and
-Moths (<i>Natural Science</i>, vol. vi. p. 293), the following passage
-occurs: ‘The only suggestion we should like to make is that a compound
-microscope is unnecessary for any of the details that the author
-mentions. A first-rate platyscopic hand lens is much more convenient<span class="pagenum" id="Page_12">[12]</span>
-and the young naturalist should train himself thoroughly in the use
-of it. There is no more common error than the undue use of the higher
-powers of a microscope. Except for the intimate details of histology, a
-low power or a hand lens is much more easy to use, and its employment
-gives a much better idea of the structure.’</p>
-
-<p>The next quotation is of greater interest, as it gives some insight
-into the way in which Darwin carried on his investigations. In the
-<i>Life and Letters of Charles Darwin</i> (vol. i. pp. 145, 146) we
-are told: ‘His natural tendency was to use simple methods and few
-instruments. The use of the compound microscope has much increased
-since his youth, and this at the expense of the simple one. It strikes
-us nowadays as extraordinary that he should have had no compound
-microscope when he went his Beagle voyage; but in this he followed
-the advice of Robert Brown, who was an authority in such matters. He
-always had a great liking for the simple microscope, and maintained
-that nowadays it was too much neglected, and that one ought always to
-see as much as possible with the simple before taking to the compound
-microscope. In one of his letters he speaks on this point, and remarks
-that he always suspects the work of a man who never uses the simple
-microscope.’</p>
-
-<p>It may be well here to verify the quotations, and also to consult
-Darwin’s <i>Naturalist’s Voyage</i>, to ascertain what kind of objects
-he examined with the simple appliances at his command. In the first
-chapter there is an interesting account of a curious limy deposit
-on the rocks of the island of St. Paul’s, and of the discoloration
-by confervae of the water, which, ‘under a weak lens, seemed as if
-covered by chopped bits of hay, with their ends jagged.’<span class="pagenum" id="Page_13">[13]</span> Then we have
-an account of the confervae in the Indian Ocean, and of infusoria so
-numerous as to tinge the water off the coast of Chile. In the second
-chapter we have observations and experiments on planarian worms.
-‘Having cut one of them transversely into two nearly equal parts, in
-the course of a fortnight both had the shape of perfect animals.’ In
-the next chapter he records some observations on the structure of
-vitrified tubes formed by lightning striking loose sand. In the fifth
-chapter is an elaborate description of a kind of sea-pen; and in the
-ninth chapter there are some remarks on the vast number of eggs in the
-egg-ribbon of a sea-slug, and on the ‘bird’s-head’ organs in certain
-Polyzoa. These remarks were, of course, founded on actual inspection
-with the simple microscope.</p>
-
-<p>To this instrument, also, we owe the discovery of the tadpole-like
-larvae of Ascidians, or Tunicates, as they are now generally called.
-‘At the Falkland Islands I had the satisfaction of seeing, in April,
-1833, and therefore some years before any other naturalist, the
-locomotive larvae of a compound ascidian.... The tail was about five
-times as long as the oblong head, and terminated in a very fine
-filament. It was, as sketched by me under a simple microscope, plainly
-divided by transverse opaque partitions, which I presume represent the
-great cells figured by Kovalevsky. At an early stage of development the
-tail was closely coiled round the head of the larva<a id="FNanchor_1" href="#Footnote_1" class="fnanchor">[1]</a>.’</p>
-
-<hr class="tb" />
-
-<p>We come now to our pocket lens, which may be purchased for a few
-shillings of any optician.<span class="pagenum" id="Page_14">[14]</span> One can buy a serviceable single lens,
-in an ebonite handle, for a shilling; and this cheap instrument is
-sufficiently powerful not only to give the worker a good general idea
-of the form and structure of objects, but to enable him to do real
-work. With it the habits of many of the inmates of his aquaria may
-conveniently be watched; he may see their development from stage to
-stage of their life-history; and with it, when they are broken up, he
-may make out a good deal of their external and internal anatomy.</p>
-
-  <div class="figcenter" id="i_014" style="width: 500px">
-     <img
-    class="p2"
-    src="images/i_014.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 1.</span>&mdash;Hand Magnifier and Stand.</p>
-  </div>
-
-<p>A very good form is shown at Fig. 1, which represents a hand magnifier,
-fitted with three lenses of different focus, generally 2 in., 1½
-in., and 1 in. Examination of the catalogues of the principal London
-opticians shows that such a set of lenses may be bought for about
-3<i>s.</i> In shape and construction there is sometimes a little
-variation; but the form figured is that most generally adopted, and is,
-on the whole, fairly convenient. It would, however, be an advantage if
-the hole by which the magnifier is mounted on the stand were drilled
-in the solid part of the handle. This would not only do away with the
-objection that the hole in the case permits dust to penetrate to the
-glasses, when carried in the pocket, but would give a longer reach, and
-thus obviate the necessity for moving the stand if the observer were
-examining a large object. The price of the stand figured is 2<i>s.</i>
-6<i>d.</i>;<span class="pagenum" id="Page_15">[15]</span> and one with a short adjusting arm ought not to cost much
-more.</p>
-
-<p>Any one with a mechanical turn may make a stand for himself, though it
-may be doubted whether this is quite worth while when these articles
-may be bought so cheaply. Nevertheless, there is great pleasure in
-making things for oneself; and a home-made stand will enable the
-observer to do quite as good work as one that came from the optician’s
-shop.</p>
-
-<p>A bill-file weighted at the foot may be bought for a few pence, and
-adapted to the purpose. For the slider a large cork cleanly pierced
-will answer admirably. This should carry a piece of stout wire, bent
-at the end thus __<img src="images/i_015.jpg" alt=""
-style="height:.8em; vertical-align: middle;" />
-, to serve as a holder for the magnifier,
-which should have a hole in the handle, for the reasons stated above.
-The only difficulty will be the attachment of the wire to the cork. The
-Rev. J. G. Wood advocated winding the wire round the cork in a spiral;
-and this is a very good plan. An increase of steadiness is secured, if
-a larger cork, or small bung, be used, and the wire inserted in the
-side.</p>
-
-<p>There are, of course, more expensive lenses, with which better
-definition can be obtained. Zeiss has an excellent magnifier consisting
-of two lenses, for use in the dissecting microscope (Fig. 2), and
-also as a hand lens, at the price of 6<i>s.</i>; one of the same
-construction, for use in the dissecting microscope alone, may be had
-for 4<i>s.</i> The Steinheil achromatic lenses are probably the best
-of all. These are made in powers ranging from 2 in. to ½ in. focus<a id="FNanchor_2" href="#Footnote_2" class="fnanchor">[2]</a>;
-and the price varies from 10<i>s.</i> up to £1, according to the maker.
-Those made by<span class="pagenum" id="Page_16">[16]</span> Leitz of Wetzlar cannot be surpassed; and they are sold
-in London at 10<i>s.</i> each, either mounted in a handle, for use
-as hand magnifiers, or with a collar for use in Leitz’s dissecting
-microscope (Fig. 3). Mr. Lewis Wright says that ‘the best plan is to
-combine both uses, and have two or three powers in collars, with a
-spring ring folding into a handle, which will carry any one of them in
-that manner. A Steinheil lens at this low price costs little more than
-a Coddington, while its performance is infinitely superior<a id="FNanchor_3" href="#Footnote_3" class="fnanchor">[3]</a>.’ It is
-a difficult thing to get makers to deviate from the beaten track, and
-so far as I have been able to learn, Mr. Wright’s wishes have not been
-fulfilled.</p>
-
-  <div class="figcenter" id="i_016" style="width: 294px">
-     <img
-    class="p2"
-    src="images/i_016.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 2.</span>&mdash;Zeiss’s Dissecting Microscope.</p>
-  </div>
-
-<p>The lenses and stand (Fig. 1) constitute a simple form of dissecting
-microscope. If the worker wishes for something more elaborate, he need
-only consult the catalogues of the principal makers to find something
-that will meet his requirements. Zeiss’s brass stand, with stage, above
-which a lens slides<span class="pagenum" id="Page_17">[17]</span> up and down in a holder (Fig. 2), is sold for
-9<i>s.</i>; with blocks for supporting the hands, at 10<i>s.</i> It is
-a useful instrument for small objects.</p>
-
-<p>My favourite instrument is shown at Fig. 3. Here the focussing of the
-lens is effected by rack and pinion work, by means of the screws on
-each side the upright pillar. The lens is shown fitted in the collar
-which carries it. The stage is of glass&mdash;roughly, 2½ in. long by 2
-in. wide, and the arm at the top of the pillar can be moved from side
-to side, so as to bring a fairly large object within range. The metal
-framework of the stage is furnished with nickelled clips (not shown),
-which serve to hold an excavated slip. The arm-rests are detachable,
-and the uprights are hinged for convenience of packing. The instrument
-(with the exception of these rests) packs into a neat, strong mahogany
-box, 7½ in. in length, and about 5 in. in height and width. With
-two powers&mdash;1 in. and ½ in. are very serviceable ones&mdash;the cost is
-38<i>s.</i></p>
-
-  <div class="figcenter" id="i_017" style="width: 500px">
-     <img
-    class="p2"
-    src="images/i_017.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 3.</span>&mdash;Leitz’s Dissecting Microscope.</p>
-  </div>
-
-<p>It is to be wished that the maker would devise some plan by which the
-admirable lenses sold with this instrument could be utilized for the
-pocket. Mr. C. Curties, of Baker &amp; Co., High Holborn,<span class="pagenum" id="Page_18">[18]</span> has kindly done
-something in the matter, and has made for me a metal holder. I have
-found this convenient, but should be glad to see something further done
-in the same direction, so that instrument, lenses, and holder could be
-sold for £2. This ought to be within the range of practical optics. The
-spring collar advocated by my friend Mr. Wright seems better, and would
-certainly be cheaper. The lenses would only need to be dropped in. To
-use my pocket holder one must unscrew the metal collar from the lenses
-before screwing them into the metal plates which carry them (Fig. 4).
-It is, however, something to have made a beginning: it is a step in the
-right direction.</p>
-
-  <div class="figcenter" id="i_018a" style="width: 450px">
-     <img
-    class="p2"
-    src="images/i_018a.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 4.</span>&mdash;Two Leitz Lenses in holder (open).</p>
-  </div>
-
-  <div class="figcenter" id="i_018b" style="width: 450px">
-     <img
-    class="p2"
-    src="images/i_018b.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 5.</span>&mdash;Two Leitz Lenses in holder (closed).</p>
-  </div>
-
-<p>A serviceable dissecting microscope&mdash;not a toy, but an instrument with
-which real work may be done&mdash;can be made at a cost of a few shillings.
-Such a one has been made for me by a friend with a positive genius
-for such work. The body is fashioned out of a parcel-post box 7 in.
-long, 3½ in. in height, and the same in width. From the centre of the
-sliding top a piece is cut away, leaving ledges to take a 3 in. by 1
-in. excavated slip for small dissections, or a mounted slide of a large
-object, such as a whole insect, for examination. A further portion is
-cut away on each side to take a small dissecting dish (Fig. 6). To
-admit the light, a hole<span class="pagenum" id="Page_19">[19]</span> is cut in the side of the box; and the mirror
-consists of a piece of silvered glass which was bought of a hawker in
-the street. This is placed in the box opposite the square hole, and
-sloped at an angle of 45°. The aid of a skilled mechanic was sought
-for a small rod carrying a thread, which works in a piece of brass
-bent at a right angle. This piece of brass is screwed on the box, just
-above the aperture by which light is admitted, and carries a pocket
-magnifier, similar to that shown at Fig. 1.</p>
-
-  <div class="figcenter" id="i_019" style="width: 450px">
-     <img
-    class="p2"
-    src="images/i_019.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 6.</span>&mdash;Home-made Dissecting Microscope.</p>
-  </div>
-
-<p>This modest little instrument generally stands on my work-table, and
-has provoked some remark and a little good-natured banter from friends
-who have seen it. Nevertheless, I should be sorry to part with it, for
-I have found it extremely serviceable in many ways. And more than one
-critic has had to confess that better results were obtained than one
-would expect from its appearance. The total cost out of pocket was,
-3<i>d.</i> for the box, 3<i>s.</i> for the lens, and 1<i>d.</i> for
-the plate-glass, while the man who made the pillar and ear-piece would
-take<span class="pagenum" id="Page_20">[20]</span> no more than 6<i>d.</i> for his work. This brings the total to
-3<i>s.</i> 10<i>d.</i> With a little ingenuity the pillar might be made
-to carry a collar, and so take a Steinheil lens. This would swell the
-total cost to about 11<i>s.</i></p>
-
-<p>Other apparatus need not be costly. An incident occurred at the meeting
-of the Quekett Microscopical Club on November 22, 1878, which shows
-how readily common objects may be utilized for our purpose. The late
-Right Hon. T. H. Huxley, who was at that time President, exhibited,
-and made some remarks on, the dissecting microscope which now bears
-his name. During the discussion which followed, Professor Charles
-Stewart exhibited some little saucers, which were admirably adapted
-for dissecting purposes. The President said that he should ‘be glad
-to know where these convenient little saucers could be obtained.’ The
-next paragraph of the minutes is interesting and instructive. ‘Mr.
-Stewart said they were to be found at the corners of the streets,
-containing three whelks or three mussels for a penny. He bought those
-he had brought to the meeting at a shop in the New Cut, where they were
-supplied to costermongers<a id="FNanchor_4" href="#Footnote_4" class="fnanchor">[4]</a>.’</p>
-
-<p>As very many of the objects with which we are concerned are aquatic,
-we shall want vessels of some sort to serve as aquaria. Any glass
-vessel will answer our purpose, provided it is clear, to allow of the
-examination of our captives; or shallow pie-dishes may be utilized.
-The glass pots in which preserves are sold will do admirably, and any
-glazier will cut us covers for a few pence. Within reasonable limits,
-the smaller the aquaria are the better. The inmates can be seen more<span class="pagenum" id="Page_21">[21]</span>
-easily, and picked out with less trouble when one wishes to examine
-them.</p>
-
-<p>The principles on which aquaria should be kept are now pretty generally
-understood. There should always be a small quantity of growing aquatic
-vegetation, and a supply of minute life to furnish food for the larger
-forms. Excess of light should be avoided, and the temperature should
-not be allowed to rise much above 50° F. Carnivorous beetles and their
-larvae may be fed with small pieces of meat, small garden worms, or
-tadpoles. Most of the smaller larvae treated of will be satisfied with
-vegetarian diet, varied with an occasional meal of water-fleas.</p>
-
-  <div class="figcenter" id="i_021a" style="width: 400px">
-     <img
-    class="p2"
-    src="images/i_021a.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 7.</span>&mdash;Beakers.</p>
-  </div>
-
-  <div class="figcenter" id="i_021b" style="width: 371px">
-     <img
-    class="p2"
-    src="images/i_021b.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 8.</span>&mdash;Glass Capsule.</p>
-  </div>
-
-<p>If one cannot lay the household stores under contribution for jam-pots,
-tumblers, and bottles, beakers (Fig. 7) make capital small aquaria.
-They are sold in nests, and may be had either rimmed or lipped&mdash;rimmed
-for choice. There is no difficulty in obtaining them of any optician or
-glass-merchant. Mine have been bought from Messrs. Beck, of Cornhill,
-as have the capsules, &amp;c., figured here.</p>
-
-<p>Glass capsules (Fig. 8) are made in different sizes, ranging from 1½
-in. to 3 in. in diameter, with<span class="pagenum" id="Page_22">[22]</span> a height of 1 in. or 2 in. The largest
-size, 3 in. by 2 in., costs 5<i>d.</i>, and a glass circle to cover it,
-1<i>d.</i> These capsules will be found useful for small aquaria, and
-for isolating aquatic larvae in order to keep them under observation
-during their change to perfect insects. It was in a capsule of this
-kind that some of my Ptychoptera larvae (p. 184) were kept, and changed
-into the pupal condition.</p>
-
-<p>The glass block, with cover (Fig. 9), is convenient for a number of
-purposes. In it small creatures may be examined in air or in water, and
-it makes an exceedingly convenient little dissecting dish for use with
-the mounted hand magnifier (Fig. 1), or with Leitz’s stand (Fig. 3), or
-the home-made stand (Fig. 6). The glass box, with cover (Fig. 10), is
-extremely good for keeping small creatures under observation.</p>
-
-  <div class="figcenter" id="i_022a" style="width: 300px">
-     <img
-    class="p2"
-    src="images/i_022a.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 9.</span>&mdash;Glass Block, with cover.</p>
-  </div>
-
-  <div class="figcenter" id="i_022b" style="width: 300px">
-     <img
-    class="p2"
-    src="images/i_022b.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 10.</span>&mdash;Glass Box, with cover.</p>
-  </div>
-
-<p>Excavated glass slips, 3 in. by 1 in., may be bought from any optician.
-They serve for the examination of objects in water, and also for
-dissection. The best I have been able to get have been supplied by Mr.
-J. Hornell, of the Biological Laboratory, Jersey, and they are very
-cheap.</p>
-
-<p>We shall need some forceps to pick up specimens from the vessels
-in which they are kept, and the same little instruments will be
-found convenient in collecting. Both forms have advantages of their
-own; if we are limited to one pair, they should be curved, and of
-brass. Forceps with ivory tips are<span class="pagenum" id="Page_23">[23]</span> very useful for handling aquatic
-vegetation. These articles are not usually sold by opticians, but
-are kept by the tradesmen in Clerkenwell who sell jewellers’ and
-watchmakers’ tools, and cost from 1<i>s.</i> to 1<i>s.</i> 6<i>d.</i> a
-pair.</p>
-
-  <div class="figcenter" id="i_023" style="width: 117px">
-     <img
-    class="p2"
-    src="images/i_023.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 11.</span>&mdash;Forceps.</p>
-  </div>
-
-<p>Dipping-tubes are used to take up small aquatic animals from the
-vessels in which they are kept. Very little practice will render the
-use of this instrument easy. The tube is held firmly between the thumb
-and the third and fourth fingers of either hand, while the index finger
-is pressed firmly on the top. Most people naturally prefer the right
-hand, but it is well to accustom oneself to use the right or left
-indifferently. The open end is then put into the water, just over the
-object to be secured, and the index finger lifted. The rush of water
-into the tube will carry the object into it, and if the finger be again
-applied to the top, the pressure of the atmosphere will prevent the
-water from escaping when the tube is lifted out<a id="FNanchor_5" href="#Footnote_5" class="fnanchor">[5]</a>.</p>
-
-<p>Small brushes are useful for taking up specimens from the water or from
-pickle; common ones will do very well for large objects, but for small
-objects and parts it is advisable to have one or two sable brushes, as
-these form a better point.</p>
-
-<p>Some needles fixed in handles will also be necessary. These may be
-bought, or made by fixing ordinary needles of requisite sizes into the
-handles sold for small brushes. The needles must be kept free from
-rust, and should always be carefully wiped after use. A good plan to
-keep<span class="pagenum" id="Page_24">[24]</span> them clean is to stick them in a gallipot in which has been
-melted a mixture of lard and paraffin in equal proportions.</p>
-
-<p>Small dissecting-knives are useful, but all the work described here may
-be done with an ordinary pocket-knife in good trim.</p>
-
-  <div class="figcenter" id="i_024" style="width: 282px">
-     <img
-    class="p2"
-    src="images/i_024.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 12.</span>&mdash;Three forms of Dipping-tube. Method
-of using it.</p>
-  </div>
-
-<p>The best preservative for our purpose is formalin, which is sold in
-a forty per cent. solution. This should be treated as absolute, and
-a five per cent. solution made. This will really be a two per cent.
-solution, and is sufficiently strong for general use.</p>
-
-<p>The most profitable use we can make of specimens is to watch their
-habits while living, and to break them up and learn as much as we can
-about their structure when they are dead. For<span class="pagenum" id="Page_25">[25]</span> us to make a collection
-of specimens in tubes would be a waste of material.</p>
-
-  <div class="figcenter" id="i_025" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_025.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 13.</span>&mdash;Mounted Needles.</p>
-  </div>
-
-<p>Little need be said about collecting. The objects treated of are
-so plentiful that no great skill, nor any wealth of appliances, is
-needed to secure an ample supply. The following remarks on the methods
-employed at the Illinois State Laboratory for the capture of aquatic
-insects and larvae are, however, worth quoting:&mdash;</p>
-
-<p>‘Insects in vegetation, and on or in the bottom, were taken by means of
-a dip-net&mdash;a net of about equal depth and width attached to a strong
-semicircular ring, firmly fixed to a long handle, the straight side of
-the ring being opposite the point of attachment. For the larger and
-more active forms, a coarser net was used, and for smaller forms one
-made of finer net proved most durable and satisfactory. To collect from
-the mud of the bottom, the water immediately over it was violently
-stirred and then swept with the net. The surface layer of mud was also
-scooped up in the fine dip-net, and then allowed to wash through,
-leaving the coarser contents in the net. Insects on the bottom in deep
-water were secured by using a dredge, and washing its contents through
-net sieves. The aquatic vegetation, when free from mud, was violently
-washed in a large pan, many smaller forms being thus dislodged and
-coming to the surface. Insects occurring in open water were taken in
-drawing an ordinary towing-net<a id="FNanchor_6" href="#Footnote_6" class="fnanchor">[6]</a>.’</p>
-
-<p><span class="pagenum" id="Page_26">[26]</span></p>
-
-<p>Here we have, so to speak, the general principles of collecting. It
-will be easy to adapt them to particular cases.</p>
-
-<p>In choosing the subjects to be treated of in this little book, some
-difficulty has been experienced in deciding what to select from the
-multitude that lay ready to hand. It was felt necessary that the
-subjects should be connected, since choosing them at random would
-lead to purposeless work, and so to waste of time and opportunity.
-After some consideration, the author has decided to take all the
-examples from the Arthrop´oda&mdash;that great sub-kingdom of backboneless
-animals which includes the Lobster, the Crab, the Sand-hopper and the
-Woodlouse, the Spider and the Mite, the whole world of Insects and the
-Centipedes. One cogent reason that influenced this decision was the
-fact that these objects are exceedingly common, so that there can be no
-difficulty in procuring material on which to work. There is, perhaps,
-no other sub-kingdom so full of interest, on account of the many widely
-different forms, which may be referred to one common plan.</p>
-
-<p>It may possibly appear to some readers that the powers of the pocket
-lens have been exaggerated. As a matter of fact the material for the
-book has been gathered by actual observation. The author has seen, with
-an ordinary pocket lens, the objects here described. If some are shown
-as they would appear under greater magnification than such a lens would
-give, this is chiefly for the sake of emphasizing points of interest
-which might otherwise be overlooked, but which can readily be made out
-with a hand magnifier, when attention has been drawn to them, and the
-observer knows what to look for.</p>
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_27">[27]</span></p>
-
-<h2>CHAPTER II<br />
-<span class="subhed">ARTHROPODS AND THEIR CLASSES.&mdash;THE MARGINED WATER BEETLE; THE
-GREAT WATER BEETLE; THE COCKTAIL BEETLE</span></h2></div>
-
-<div>
-<img class="drop-cap" src="images/i_027.jpg" width="50" alt="" />
-</div>
-
-<p class="drop-cap p-left">Having got together our apparatus, which, as we have seen, need be
-neither costly nor complicated, the next step will be to acquire some
-knowledge of the group from which the examples here treated of will be
-taken&mdash;the Ar´thropods, or animals with hollow-jointed limbs. These
-are the ‘Insects’ of the Linnaean classification, and, for the matter
-of that, of popular phraseology; for though few people would now
-venture to call a Lobster an ‘insect,’ we still style some of its near
-relatives Water ‘Fleas,’ as Swammerdam did two hundred years ago.</p>
-
-<p>The Arthropods form a phylum, or main division of the Animal Kingdom.
-Above this phylum comes that of the Molluscs, or soft-bodied animals,
-such as the Oyster, the Snail, and the Cuttlefish. Still higher are the
-Lancelet, the Sea-squirts, and some few others, that bridge the chasm
-between the phyla without, and that phylum with, a backbone. And to
-this last Man himself belongs.</p>
-
-<p>Two reasons contributed to the selection of the Arthropods as a subject
-for work with the pocket lens: (1) the great interest which surrounds
-many of the group; and (2) the ease with which specimens may be
-procured and kept under observation.</p>
-
-<p><span class="pagenum" id="Page_28">[28]</span></p>
-
-<p>Every one has pretty clear notions as to the general ‘make’ of a
-Vertebrate or backboned animal. An Invertebrate animal has, of course,
-no backbone or the semblance of one; the nervecord, where present, lies
-on the under surface, and forms a ring round the gullet, and the heart
-lies on the upper surface or back. We may verify this by pulling to
-pieces a dead insect.</p>
-
-<p>But a phylum, or main division, is much too large to be considered as a
-whole. It must, therefore, be broken up into smaller groups, which are
-called Classes, generally reckoned as five in number. These, again, may
-be grouped into two divisions, according as their members breathe by
-means of air-tubes (<i>tracheae</i>) or by gills. Our scheme then will
-stand thus:&mdash;</p>
-
-<table summary="scheme" class="smaller">
- <tr>
-    <td class="cht2" rowspan="5">ARTHROPODS</td>
-    <td class="brckt" rowspan="5"><img src="images/big_left_bracket.png" alt="big left bracket"
-      style="height:8em; padding:0 1em 0 1em;" /></td>
-    <td class="cht2" rowspan="4">Breathing by air-tubes</td>
-    <td class="brckt" rowspan="4"><img src="images/big_left_bracket.png" alt="big left bracket"
-      style="height:6.5em; padding:0 1em 0 1em;" /></td>
-    <td class="cht">Peripatus.</td>
-  </tr>
-
-  <tr>
-    <td class="cht">Centipedes and Millipedes.</td>
-  </tr>
-
-  <tr>
-    <td class="cht">Insects.</td>
-  </tr>
-
-  <tr>
-    <td class="cht">Spiders and their kin.</td>
-  </tr>
-
-  <tr>
-    <td class="cht">Breathing by gills</td>
-    <td class="cht"></td>
-    <td class="cht">Lobsters, Crabs, Sand-hoppers, and Woodlice.</td>
-  </tr>
-</table>
-
-<p>This scheme looks well on paper; and on the whole is workable. But
-among our examples chosen from the Class of Insects, we shall find some
-that breathe by gills in their larval stage, and by air-tubes when
-adult. And among the Crabs are some, the gills of which have ceased
-to perform their normal function, so that these animals cannot live
-in water for a single day. And then there are the Sand-hoppers and
-Woodlice.</p>
-
-<p>The body of an Arthropod may be represented by a series of similar
-rings, thus:</p>
-
-  <div class="figcenter" id="i_028">
-     <img
-    class="p0"
-    src="images/i_028.jpg"
-     alt="" />
-  </div>
-
-<p>This similarity is clearly apparent in the Centipede, but is concealed
-in the Beetle, the Shrimp, and<span class="pagenum" id="Page_29">[29]</span> the Spider. It seems, at first sight,
-to be altogether lost in the Crab, and does really vanish in the adult
-stage of some parasitic Crustaceans.</p>
-
-<p>It may be plausibly objected that our ideal Arthropod resembles nothing
-so much as a worm. In many respects this is true. A primitive Arthropod
-was worm-like, as is a Centipede. And Arthropods and Worms were
-formerly classed together in one group, as Annulo´sa or ringed animals.
-The chief external difference lies in the nature of the appendages
-borne by the various rings or segments.</p>
-
-<p>We may represent those of the Worms thus <img src="images/i_029a.jpg" alt=""
-style="height:2em; vertical-align: middle;" />, for they are
-bristles, or groups, or modifications of bristles. Those of the
-Arthropods may be represented thus <img src="images/i_029b.jpg" alt=""
-style="height:2em; vertical-align: middle;" />, for the appendages are
-really jointed, though, of course, in a fashion different from those of
-a backboned animal.</p>
-
-<p>The jointed appendages of Arthropods may be modified to fulfil very
-different functions. They may serve as legs for walking, hands for
-climbing or seizing prey, jaws for masticating food, feelers or organs
-of touch and sense, and, strange as it may seem, in one group, as eyes.</p>
-
-<p>It is well to get some notion of how these joints are formed. To take
-the body first: the skin connecting the segments is much thinner than
-that of the segments themselves, which is thickened by the deposition
-of chitine, and, in some cases, also of carbonate and phosphate of
-lime. A portion of the body, then, may be represented thus,
-<img src="images/i_029c.jpg" alt=""
-style="height:2em; vertical-align: middle;" /> where the heavy lines denote the segments, and the thin ones the spaces
-between the segments. It will be seen that this arrangement<span class="pagenum" id="Page_30">[30]</span> allows
-of considerable play, and also of a telescopic movement by which the
-segments can be brought close together.</p>
-
-<p>It is easy to construct a kind of model that shall exemplify these
-movements. Make a tube of calico, some six inches long, and having
-stuffed it with cotton-wool, paste on it strips of brown paper one inch
-in width, leaving an interval between each, as in the last diagram.
-Then we shall be able to understand how Arthropods can bend the body or
-move it from side to side. And the limb joints are made on a similar
-plan.</p>
-
-  <div class="figcenter" id="i_030">
-     <img
-    class="p2"
-    src="images/i_030.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 14.</span>&mdash;Cape Peripatus (natural size).</p>
-  </div>
-
-<p>The most archaic Arthropod&mdash;Perip´atus&mdash;must be mentioned. It is not
-found in Britain, nor even in Europe; so that, unless we travel, we
-shall only know it from books, or from museum specimens. But it is an
-extremely interesting creature, for it is of worm-like aspect, and
-breathes by air-tubes, opening all over the body, which has no external
-segments. The limbs are imperfectly jointed, and each of them bears
-two claws. Most naturalists make this genus a Class by itself, while
-some put it with the Centipedes. There are about a dozen species, four
-of which are African, two Australian, and the rest are found in South
-America and the West Indies. Besides these there are some doubtful
-species.</p>
-
-<p>In habit they resemble the Centipedes, and they<span class="pagenum" id="Page_31">[31]</span> ensnare the insects on
-which they feed by ejecting sticky slime from the small processes near
-the mouth. The left process is shown in the illustration, just below
-the antenna of that side.</p>
-
-<p>Professor Sedgwick, who described these animals in the <i>Quarterly
-Journal of Microscopical Science</i> (1888), and, more popularly,
-in the <i>Cambridge Natural History</i>, says, that ‘the exquisite
-sensitiveness and changing form of the antennae, the well-rounded plump
-body, the eyes set like small diamonds on the side of the head, the
-delicate feet, and, above all, the rich colouring and velvety texture
-of the skin, all combine to give these animals an aspect of quite
-exceptional beauty.’</p>
-
-<p>Unfortunately, an illustration in black-and-white can only render
-form. We must take the beauty of the colouring for granted. One thing,
-however, cannot escape the most cursory examination of the picture&mdash;the
-resemblance of the creature, in some respects, to a worm, and, in
-others, to a caterpillar, which, as everybody knows, is the larval
-stage of a butterfly. If this resemblance sets us thinking how it came
-about, and what it means, Peripatus will, for the present, have done
-its work for us.</p>
-
-<hr class="tb" />
-
-<p>With these general notions of Arthropods, we may pass on to put our
-pocket lens to some practical use. Our first subject shall be the
-Margined Water Beetle (<i>Dytis´cus margina´lis</i>), which can be
-taken in almost any open pond in the country. Water covered with
-duckweed should be avoided in hunting for these beetles, which prefer
-ponds with a clear surface, so that they may easily come to the top to
-breathe.</p>
-
-<p>Every one has a good general notion of the principal Insect-groups,
-technically called Orders&mdash;Beetles,<span class="pagenum" id="Page_32">[32]</span> Cockroaches and Grasshoppers,
-Butterflies, Bees and Wasps, and Flies. Insects may be defined
-as animals with hollow-jointed limbs, and divided into three
-regions&mdash;head, thorax, and abdomen. The head bears a pair of antennae;
-the thorax carries three pairs of legs, and (generally) two pairs of
-wings; the abdomen is without appendages. Insects when adult breathe
-by tubes that open to admit air. In Chapter VI we shall see that many
-larvae obtain an air supply in different ways.</p>
-
-  <div class="figcenter" id="i_032" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_032.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 15.</span>&mdash;Margined Water Beetle (male).</p>
-  </div>
-
-<p>Beetles may be taken as very good types of true Insects. They
-constitute the Order Coleop´tera, or Insects with sheathed wings, only
-the hinder pair being used for flight (Fig. 18), and at other times
-they are folded under the wing-cases, or el´ytra, as in Fig. 15.</p>
-
-<p>We may advantageously compare our Beetle with Peripatus, and note the
-points of agreement and of difference.</p>
-
-<p>Now, if our captive Beetles are to yield us the greatest possible
-amount of profit, we shall keep them under observation for some time,
-so as to watch their habits.</p>
-
-<p>In keeping these Beetles we shall not require a large aquarium. A small
-gathering of aquatic weed will be necessary to keep the water in good
-condition and the aquarium ready for its tenants.</p>
-
-<p>My interest in these Beetles was quickened by<span class="pagenum" id="Page_33">[33]</span> a letter in the
-<i>Field</i> (Oct. 28, 1893), in which a correspondent at Weybridge
-asked ‘for information as to what animal or bird bisects so neatly the
-shells of the Water Snail (<i>Planorbis</i>).’ I thought then, and
-know now, that the shells were ‘bisected,’ if that is the proper word,
-by Water Beetles. From that time I have had, and still have, several
-living in small aquaria, but for a long time was unable to get direct
-evidence on the subject.</p>
-
-  <div class="figcenter" id="i_033" style="width: 400px">
-     <img
-    class="p2"
-    src="images/i_033.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 16.</span>&mdash;Shells of Molluscs broken up by
-Dytiscus.</p>
-     <p class="p0 sm center">(From a photograph by Cherry Kearton.)</p>
-  </div>
-
-<p>Many experiments were tried, and at last these proved successful.
-Several specimens of Dytiscus<a id="FNanchor_7" href="#Footnote_7" class="fnanchor">[7]</a><span class="pagenum" id="Page_34">[34]</span> were obtained, and put into a small
-aquarium in which was no other food for them than some snails and other
-molluscs. The Beetles were carefully watched, and were several times
-seen trying the snails. In crawling along the inner surface of the
-glass, Planorbis and Limnaea both protrude the foot to a considerable
-extent, and pieces were ripped out by the strong mandibles of the
-Beetles before the shells were actually broken up.</p>
-
-<p>All the shells represented in Fig. 16 were taken from this aquarium,
-so that there is good evidence as to what creatures broke them up and
-devoured their inmates. In these, as in the specimen kindly sent me by
-Mr. Tegetmeier, the Natural History Editor of the <i>Field</i>, the
-bisection is not complete, though in all cases it is carried far enough
-to allow of the extraction of the mollusc. The large Limnaea shell in
-the centre has been attacked, but it seems to have been left when the
-beetles discovered it was empty. (The empty shell was noted before the
-Beetles were put into the tank.) Another Limnaea shell is figured, from
-which the snail has been picked out, and that of a fresh-water mollusc.</p>
-
-<p>After these observations had been recorded in the <i>Field</i><a id="FNanchor_8" href="#Footnote_8" class="fnanchor">[8]</a>, I
-found that I had been anticipated by about forty years. I picked up,
-at a bookstall, a copy of G. B. Sowerby’s <i>Popular History of the
-Aquarium</i>, and there I found that the author had distinctly seen
-Dytiscus at this kind of work. He says<a id="FNanchor_9" href="#Footnote_9" class="fnanchor">[9]</a>: ‘I have only once witnessed
-him in the act of seizing an unfortunate Planorbis or Flat-coiled Water
-Snail. At first, the Dytiscus seemed to be roaming about in quest
-of something, first under,<span class="pagenum" id="Page_35">[35]</span> then over, the leaves of a water-lily.
-At last, in a rather dark corner, he seemed to perceive suddenly a
-Planorbis which was browsing upon the stem of a plant just under the
-shade of a broad leaf. He darted at this, seized it, and then, putting
-his tail out of water, for the purpose of taking in a fresh supply of
-air, moved slowly down, bearing the snail with him. He held it by his
-fore-feet, turning round the coil until the aperture of the shell was
-opposite his mandibles, then he began nibbling away at the animal. In
-vain did the poor mollusc try to withdraw within its shelly fortress,
-for the beetle picked off the edges of the shell bit by bit, so as to
-expose the body as fast as it was withdrawn. All the way down to the
-bottom of the tank was this process continued, air-bubbles rising to
-the top, and bits of broken shell falling, till the beetle with his
-burden reached a stone near the bottom, where I left him still busy at
-his work.’</p>
-
-<p>This puts the matter beyond doubt, if any before existed. I at once
-wrote to Mr. Tegetmeier to let him know that my experiments had,
-unknown to me, been anticipated, long ago, by Mr. Sowerby. Had
-he rescued his Planorbis shell, it would have compared very well
-with those forwarded to the <i>Field</i> office in 1893. They had
-been exhibited at the Malacological Society, and no one was able
-to solve the mystery of their mutilation. This shows, to quote the
-<i>Field</i><a id="FNanchor_10" href="#Footnote_10" class="fnanchor">[10]</a> on the subject, ‘how easily statements that have been
-recorded may subsequently be overlooked and entirely forgotten.’</p>
-
-<p>To return to our Beetle. The male is a handsome creature, from an inch
-to an inch and a<span class="pagenum" id="Page_36">[36]</span> quarter long, clad in olive-green, bordered with
-yellow, and exceedingly active. His mate is smaller, more soberly clad
-in brown, without the yellow markings, and the wing-cases are more or
-less furrowed.</p>
-
-<p>The first thing to notice is the shape of the body, oval and smooth,
-offering no resistance to the water. The hind pair of legs are
-flattened and fringed with hairs, so as to make capital paddles. In
-swimming the right and left legs are moved together.</p>
-
-<p>Now, though this Beetle lives in the water, it is made, so far as
-concerns its breathing apparatus, after the fashion of a Land Beetle,
-and consequently is compelled to come to the surface pretty frequently
-for a supply of air, which it obtains in this wise. Directly it ceases
-paddling it floats to the top of the water; and as the head is heavier
-than the tail the latter projects a little above the surface. Then the
-wing-cases are raised, and air flows in under them to the breathing
-holes on each side. The operation is not a long one, and as soon as it
-is over the Beetle is ready for another ramble round his dwelling-house.</p>
-
-<p>But if we do not supply our captive with food that he may take for
-himself, it is only right that we should feed him, which may be done at
-intervals&mdash;say, every other day. ‘Little, and often,’ is an excellent
-motto to guide us in our feeding; and though its adoption may entail
-some trouble, it will be more than compensated by the success that
-will attend our endeavours to keep the inmates of our aquarium in good
-condition. And the operation of feeding our Beetle will show us that he
-has some capital sense-organs, which are of as much, if not of more,
-use to him than his eyes.</p>
-
-<p><span class="pagenum" id="Page_37">[37]</span></p>
-
-<p>He is a flesh-eater. Let us take a small piece of meat or fish in a
-pair of forceps, or stuck on a pointed stick, and hold it at a little
-distance from his great eyes. The chances are that he will not see it.
-Even if we put it in front of him, he is quite likely to disregard it,
-for he has nothing corresponding to a nose, with which he may smell.
-From his head there spring a pair of long feelers&mdash;the antennae&mdash;and by
-means of these we will let him know that his dinner is ready. That is
-effected by drawing the food along the side of one of the antennae. The
-creature undergoes a sudden change. Till the antenna was touched with
-the food he was resting on his swimming legs. But in a moment down goes
-his tail and up goes his head, he stretches out his raptorial legs, and
-clutches wildly at the forceps or stick, as the case may be, holding so
-tight that he may be dragged round and round the glass vessel. Let go
-he will not, of his own accord; and it would be a difficult matter to
-shake him off. Similar experiments may be tried with other Beetles, and
-the result will be to impress on the mind the fact that the feelers are
-capital sense-organs.</p>
-
-<p>If we are to turn our Beetle to the best account, we shall need to
-handle him. It may be inconvenient to wait till he dies, so we will
-kill him quickly and painlessly by plunging him into boiling water, and
-he may be preserved by putting him into a tube containing about equal
-parts of water and spirit, or a five per cent. solution of formalin.</p>
-
-<p>Dissections should properly be made under water. The Beetle should be
-fastened, back upwards, to a piece of cork weighted with lead, and
-placed in a deep saucer, or dissecting dish, and covered with<span class="pagenum" id="Page_38">[38]</span> water.
-But a good deal of rough dissection, as is ours, may be done in air,
-and the Beetle may be fastened to any convenient piece of board, or
-even held in the palm of the left hand. Very little practice is needed
-to run over the external parts of a large Beetle in this manner.</p>
-
-  <div class="figcenter" id="i_038" style="width: 459px">
-     <img
-    class="p2"
-    src="images/i_038.jpg"
-     alt="" />
-     <p class="p0 sm hangingindent"><span class="smcap">Fig. 17.</span>&mdash;Outline of Dytiscus (male). <i>a</i>,
-antenna; <i>b</i>, maxillary palp; <i>c</i>, eye; <i>d</i>,
-fore-leg; <i>e</i>, thorax; <i>f</i>, middle leg; <i>g</i>,
-elytron; <i>h</i>, suture; <i>i</i>, hind leg; <i>j</i>, claw;
-<i>k</i>, tarsus or foot; <i>l</i>, tibia or shank; <i>m</i>,
-femur or thigh; <i>n</i>, first three joints of foot, widened
-into a plate with suckers beneath.</p>
-  </div>
-
-<p>First, let us look over our Beetle, and get some general notions of
-its make. As it lies, back upwards, it is clear that it consists of
-three parts or regions&nbsp;&mdash;&nbsp;&mdash;&mdash;&nbsp;&mdash;&mdash;&mdash;, the first of which is the
-head, the second the thorax, and the third the abdomen. Not only in our
-Beetle, but in Insects generally, these parts correspond to the words
-that denote them, in that the thorax is longer than the<span class="pagenum" id="Page_39">[39]</span> head, and the
-abdomen longer than the thorax, as shown by the three dashes, a few
-lines above.</p>
-
-<p>These divisions are well shown in Fig. 17, where other parts are also
-marked. It will pay to go over our own specimen with this figure before
-us, and so make acquaintance with the several parts, to some of which
-we shall return in greater detail.</p>
-
-  <div class="figcenter" id="i_039" style="width: 300px">
-     <img
-    class="p2"
-    src="images/i_039.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 18.</span>&mdash;Male Dytiscus in flight.</p>
-  </div>
-
-<p>At this point, if we have not done so before, it will be convenient
-to fasten our Beetle, in the position figured, by a stout pin driven
-between the thorax and the abdomen, just above the suture (<i>h</i>).
-We want to raise one of the wing-cases.</p>
-
-<p>If a needle be taken in each hand, between the thumb and first two
-fingers, and that in the left hand be used to steady the creature, the
-wing-case on the right may be raised with the needle in the right hand,
-and then cut off. The small filmy membrane, of somewhat triangular
-shape, which<span class="pagenum" id="Page_40">[40]</span> comes off with the wing-case, is the winglet. There is
-one on each side; and their vibration causes the humming noise made by
-these insects in flight. When the water dries up in one pond, or food
-becomes scarce, they will leave and fly off to another.</p>
-
-<p>The wing lies folded upon the abdomen. A good deal of very interesting
-matter has been written on the way in which Insects fold their wings,
-but we can see for ourselves how this Beetle folds them. All we have to
-do is to take the wing, and draw it gently away from us, and so unfold
-it. We may use finger and thumb, or a small pair of forceps. When let
-go, it will spring back to its old position. Reference to the expanded
-wing in Fig. 18, and to the diagrams Figs. 19 and 20, will show how the
-wing is folded.</p>
-
-  <div class="figcenter" id="i_040a" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_040a.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 19.</span>&mdash;To show fold of (right) wing of
-Dytiscus.</p>
-  </div>
-
-  <div class="figcenter" id="i_040b" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_040b.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 20.</span>&mdash;To show fold of (right) wing of
-Dytiscus.</p>
-  </div>
-
-<p>The cross-mark in the diagram represents a joint in the chitinous rod
-that forms the wings. This lies just above the cell (which is left
-white in Fig. 18). The shorter part of the rod is bent down, forming an
-acute angle (Fig. 20); of course, carrying with it the membranous part
-of the wing.</p>
-
-<p>This may seem a little difficult. But if it be tried on a specimen, no
-real difficulty will be experienced. When the wing has been unfolded,
-it will, if let go, spring back to its old position, the shorter part
-lying underneath, and the chitinous rod fitting into a groove formed by
-the projecting sides of the segments of the abdomen.</p>
-
-<p>To this point the sum of our knowledge about<span class="pagenum" id="Page_41">[41]</span> Dytiscus amounts
-to this: It is aquatic in habits; its body is divided into three
-regions; and it has a pair of membranous wings, covered by chitinous
-wing-cases, or sheaths, technically called <i>el´ytra</i> (each being
-an <i>el´ytron</i>). Wing-cases of this kind are the distinguishing
-mark of the Beetles, or <i>Coleop´tera</i>, though they are not always
-so well developed as in the specimen with which we are dealing. This we
-can discover for ourselves by examining all the Land Beetles met with
-in a country ramble or in a stroll round the garden.</p>
-
-<p>Now let us unpin our Beetle, turn it on its back, and examine it from
-the under side. Head, thorax, and abdomen may be made out more clearly
-than before, and we can see that the last two regions are divided into
-segments.</p>
-
-<p>Let us deal with the head first. This may be easily separated from the
-thorax with a dissecting needle, or with a pocket-knife&mdash;an exceedingly
-handy tool. The huge goggle-eyes cannot escape observation; and, even
-without a magnifier, they may be seen to be compound&mdash;that is, made up
-of a number of facets, which show like a fine network.</p>
-
-<p>Just in front of the eyes are the antennae, which serve as organs of
-touch and perhaps also of other senses.</p>
-
-<p>Kirby has recorded facts which seem to show that the antennae (in
-some cases) are also organs of hearing. Other authorities, after many
-observations, have come to the same conclusion. The matter, however,
-is beset with difficulty. It is certain that some Insects have their
-ears in their legs; and for the present, at any rate, we may be
-satisfied to know that the antennae are sense-organs, certainly of
-touch, probably of smell, and,<span class="pagenum" id="Page_42">[42]</span> in some cases, of hearing. An excellent
-authority on the subject is Sir John Lubbock’s book, <i>The Senses of
-Animals</i><a id="FNanchor_11" href="#Footnote_11" class="fnanchor">[11]</a>, which contains references to very many original papers.</p>
-
-  <div class="figcenter" id="i_042a" style="width: 433px">
-     <img
-    class="p2"
-    src="images/i_042a.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 21.</span></p>
-     <p class="p0 sm hangingindent"><span class="smcap">Fig. 21.</span>&mdash;Upper surface of head of Dytiscus. <i>a</i>,
-labrum, or upper lip; <i>b</i>, clypeus or shield; <i>c</i>,
-mandible dissected out, and (<i>d</i>) reversed; <i>e</i>, eye;
-<i>f</i>, antennae.</p>
-  </div>
-
-  <div class="figcenter" id="i_042b" style="width: 450px">
-     <img
-    class="p2"
-    src="images/i_042b.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 21<span class="allsmcap">a</span>.</span></p>
-     <p class="p0 sm hangingindent"><span class="smcap">Fig. 21 a.</span>&mdash;Under surface.
-<i>a</i>, mentum or chin; <i>b</i>, ligula or tongue; <i>c</i>,
-labial palp; these three together forming the labium, or lower lip;
-<i>e</i>, eye; <i>f</i>, antennae. Above the maxillae, or lower jaws
-(<i>d</i> <i>d</i>), are shown dissected out: <i>d<sup>1</sup></i>,
-inner or palpiform lobe; <i>d<sup>2</sup></i>, maxillary palp;
-<i>d<sup>3</sup></i>, lacinia or blade; <i>d<sup>4</sup></i>, the
-palpifer or piece that bears the palp (<i>d<sup>2</sup></i>);
-<i>d<sup>5</sup></i>, stipes or stalk; <i>d<sup>6</sup></i>, the cardo
-or hinge.</p>
-  </div>
-
-<p>Now we may pass to the mouth parts. It will be good practice to dissect
-these out, either in air or in water. We may hold a Beetle between the
-finger and thumb of the left hand, and separate all the parts with a
-needle held in the right. It is a good plan to gum these parts on a
-card, for comparison with the figures in our favourite book&mdash;whatever
-that may be&mdash;on Natural History, and also with the mouth parts of
-insects of other Orders. For however much these may differ in form,
-and<span class="pagenum" id="Page_43">[43]</span> in the uses to which they are put, they are really modifications
-of the same parts.</p>
-
-<p>In Fig. 21 we have the upper side and in Fig. 21<span class="allsmcap">A</span> the under
-side of the head represented, so that we may easily get acquainted
-with the different parts, and the names given to them. The cut should
-be gone over several times, and the parts in the picture compared with
-those in the specimen under consideration. It is good practice to
-endeavour to draw what is seen from the specimen itself, and then to
-compare the result with the work of the trained artist. And the mouth
-parts of Dytiscus may be compared with the mouth parts of the Cockroach
-(Fig. 33).</p>
-
-  <div class="figcenter" id="i_043" style="width: 210px">
-     <img
-    class="p2"
-    src="images/i_043.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 22.</span>&mdash;Disposition of mouth parts.</p>
-  </div>
-
-<p>Returning to practical work, the first thing is to separate
-the <i>labrum</i>, or upper lip, from the head. Then the large
-<i>mandibles</i> should be dissected out, and cleaned (by soaking in
-caustic potash) from the muscles which will come away with them. Behind
-these are a smaller pair of jaws, the <i>maxillae</i>, furnished with
-a pair of palps, called maxillary palps from their position. These are
-to be dissected out; and then the lower lip, or <i>labium</i>, may be
-separated by passing a sharpened needle along the line where it joins
-the chin. The palps on the lower lip are called labial palps.</p>
-
-<p>When these parts are cleaned and dried, they should be gummed on card,
-as shown in Fig. 22, where the long lines represent the upper and lower
-lips respectively, and the shorter ones the mandible and maxilla of
-each side.</p>
-
-<p>So much for the head. Now we discover that what appeared to be the
-thorax, when we were looking at the upper surface of the Beetle, and<span class="pagenum" id="Page_44">[44]</span>
-what is called the thorax in descriptions of Beetles, is really but
-a portion of that region, which is seen to be divided into segments.
-The covering on the upper surface protects only the first segment,
-the middle and hinder ones being covered by the wing-cases and the
-<i>scutellum</i> (a triangular piece jutting backward from the second
-segment, and meeting the suture). This is not represented in Fig. 17;
-but we may put in with our pen a tiny triangle, with its base towards
-the head, and its apex towards the tail&mdash;this will meet the case.</p>
-
-<p>The first segment bears no appendage above, but to the under side is
-attached the first pair of legs. The middle segment also carries a pair
-of legs, and on its upper surface are the wing-cases, to the under side
-of which, and to the body, the winglets are joined. The last segment
-bears the wings above, and the last pair of legs below, these being
-placed very far back, so as to give them greater power in propelling
-the animal through the water.</p>
-
-<p>It will be convenient to examine the legs next. First, however, it
-will be well to look at a normal leg of an Insect (the Cockroach), and
-learn the names of the different parts. First comes the <i>coxa</i>
-(<i>a</i>) or haunch, next the <i>trochanter</i> (<i>b</i>), then the
-<i>femur</i> (<i>c</i>) or thigh, the <i>tibia</i> (<i>d</i>) or shank,
-and the <i>tarsus</i> (<i>e</i>) or foot, ending in a pair of claws.
-There are three pairs of legs in perfect Insects, and usually the same
-number in larval forms, though in some of these legs are entirely
-wanting.</p>
-
-  <div class="figcenter" id="i_044">
-     <img
-    class="p2"
-    src="images/i_044.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 23.</span>&mdash;Leg of Cockroach.</p>
-  </div>
-
-<p>In the males of the Margined Water Beetle and many of its near
-relations the first pair of legs<span class="pagenum" id="Page_45">[45]</span> deserve special attention. The first
-three joints of the tarsus have coalesced to form a disk or cup, which
-in our specimen bears two smaller ones on its inner surface. A power
-of 20 will show the disk nearly as well as it appears in Fig. 24.
-The purpose of this disk, or clasper, which is absent in females, is
-obvious. It was formerly supposed to act as a sucker, but Professor
-Lowne and Professor Miall<a id="FNanchor_12" href="#Footnote_12" class="fnanchor">[12]</a> have shown that it does not act by
-atmospheric pressure, but by a viscid secretion discharged from the
-cup-like hairs with which the inner surface is set.</p>
-
-  <div class="figcenter" id="i_045" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_045.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 24.</span>&mdash;Tarsus of Dytiscus (magnified).</p>
-  </div>
-
-<p>The middle pair of legs in the male also bear cup-like hairs on the
-corresponding joints of the tarsus, and in very much greater number.
-Professor Miall quotes Simmermacher to the effect that while the large
-disk on the fore-leg has 170 sucking-hairs, the enlarged joints of
-the tarsus of the middle leg bear no less than 1590. These hairs are
-plainly discernible with the half-inch Steinheil, and I have made them
-out with the inch, and think that I could show them to anybody else
-with that power. I have not looked for these sucking-hairs on the
-middle leg of other Beetles of the same family which have disks on<span class="pagenum" id="Page_46">[46]</span>
-their fore-legs, but they do exist in some other genera.</p>
-
-<p>If we watch a male Dytiscus in life, in a small aquarium, we shall soon
-be convinced that Lowne and Miall are correct in their statement that
-the cup-hairs discharge an adhesive substance. We shall see this all
-the more plainly if there is much floating vegetation. For, in swimming
-about, the Beetle will often come in contact with some of this, and it
-will adhere to the cup-hairs. His struggles to free himself from the
-encumbrance will show that the attachment is not altogether under his
-control. The offending weed is rubbed against the spines of one of the
-other legs till it is removed.</p>
-
-  <div class="figcenter" id="i_046" style="width: 350px">
-     <img
-    class="p2"
-    src="images/i_046.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 25.</span>&mdash;Female Dytiscus swimming.</p>
-  </div>
-
-<p>The spines with which the legs are set are worthy of a good deal of
-attention, and, like the adhesive cup-like hairs, though in different
-fashion, they doubtless assist the animal in holding its prey. The
-first and middle legs end in strong claws; those of the last pair are
-not so well developed.</p>
-
-<p>The last pair of legs are the swimming organs. The tibia and tarsus
-are fringed with long stiff hair<span class="pagenum" id="Page_47">[47]</span> behind, so as to hold the water
-when the Beetle swims. A peculiar arrangement of the first joint of
-the tarsus allows the edge to be presented to the water when the limb
-is carried forward for the return stroke, thus offering the least
-possible resistance. This Dr. Sharp has compared to the action of a
-rower in feathering his oar. There is, however, this difference, which
-it is well to note. The oar is feathered after the stroke; the Beetle
-feathers its legs before the stroke. It is the first motion when it
-begins to swim, and the action is not peculiar to the male.</p>
-
-<p>We now come to the third region, the abdomen. Like the thorax it is
-visibly divided into segments, though the division between them is
-not so great. Much difference of opinion exists as to the number of
-segments in the abdomen of a typical insect. Some authorities maintain
-there are eleven, while others put the number as low as five. This,
-however, is theoretical rather than practical. It is enough for us
-to know that the number apparently varies greatly, owing to the
-coalescence of two or more of the segments.</p>
-
-  <div class="figcenter" id="i_047" style="width: 208px">
-     <img
-    class="p2"
-    src="images/i_047.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 26.</span>&mdash;Upper surface of abdomen of typical Beetle.</p>
-  </div>
-
-<p>The head in Insects, we have seen, carries the eyes, antennae, and
-feeding organs. The thorax bears the legs and wings. The abdomen bears
-no appendages, except in some cases, on the last segment; these are
-called <i>cerci</i>. It may be, however, that the stings of bees and
-the ovipositors of saw-flies and other insects are modified appendages.</p>
-
-<p>On examining the abdomen of Dytiscus we shall probably be struck with
-the difference in appearance<span class="pagenum" id="Page_48">[48]</span> between the upper and the under surfaces.
-The latter is hard, smooth, and shiny; the former, when the wings are
-removed, is seen to be covered with felt-like hair.</p>
-
-<p>Our interest is with the upper surface. Along the abdomen on each
-side lie spiracles, stigmata, or openings to the breathing tubes. The
-first and last are larger than the rest, and their general form can be
-readily made out with an inch magnifier, and with the half-inch we may
-get some idea of the detail shown in Fig. 27.</p>
-
-  <div class="figcenter" id="i_048a" style="width: 223px">
-     <img
-    class="p2"
-    src="images/i_048a.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 27.</span>&mdash;Spiracle of Dytiscus (magnified).</p>
-  </div>
-
-<p>Dytiscus breathes in this way. Floating up to the top of the water,
-the end of the abdomen projects above the surface. If one watches the
-Beetle the wing-cases will be seen to rise a little. The air retained
-by the felted hairs is given off, and a further supply taken in. Then
-the wing-cases are lowered again; the Beetle gives two or three strokes
-with its swimming legs, and descends below the surface to ramble round
-the tank in search of food.</p>
-
-  <div class="figcenter" id="i_048b" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_048b.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 28.</span>&mdash;Tracheal tubes (magnified).</p>
-  </div>
-
-<p>This air-supply between the wing-cases and the abdomen is taken in at
-the spiracles<span class="pagenum" id="Page_49">[49]</span> and distributed through the tracheal tubes throughout
-the body. These tubes branch and subdivide till they end in small
-twig-like vessels comparable to the capillaries of the human body.
-They consist of two layers&mdash;the inner strengthened by what probably is
-a spiral fibre, though Packard believes that, in some cases at least,
-it consists of similar rings. But we must not pursue this subject. It
-would lead us beyond our appointed limits.</p>
-
-<hr class="tb" />
-
-<p>Another Beetle fairly common in stagnant waters round London and in
-the southern counties is that to which the name Great Water Beetle
-(<i>Hydroph´ilus pic´eus</i>) of right belongs. This name is sometimes
-wrongly applied to Dytiscus, with which its rightful owner has
-little in common, except its aquatic habitat. Its scientific name is
-<i>Hydrophilus piceus</i>; but we shall speak of it as Hydrophilus.</p>
-
-<p>It is not a very easy matter to take this Beetle with a net, by
-sweeping in the ordinary way, for it likes to get into the middle of
-a mass of vegetation, where it is sure of a good food supply, and is
-probably safe from the attacks of Dytiscus, who not unfrequently makes
-a meal of his larger relation. A good plan is to pass the net under a
-mass of weed and then shake it to and fro in the water. By this means
-any Beetles in the weed will be dislodged from their hiding-places, and
-fall down into the bottle.</p>
-
-<p>They have, in confinement, the same habit of making a snug place
-for themselves; and more than once I have fancied that a Beetle of
-this species had escaped from the aquarium, when all the time it was
-hidden in a thick patch of water-moss. They are practically vegetable<span class="pagenum" id="Page_50">[50]</span>
-feeders, though Dallas says that they are not such strict vegetarians
-as to deny themselves a meal of animal food when they meet with a dead
-mollusc or larva in the course of their wanderings. I have never known
-them to indulge in animal food, dead or living, but I have known them
-refuse it.</p>
-
-<p>Hydrophilus is the largest British Water Beetle, and, with the sole
-exception of the Stag-Beetle, the largest British member of the Order.
-Its total length is very little less than two inches, and across the
-middle of the back it measures about half as much. It is more slenderly
-built than Dytiscus, and the contrast in the size and armature of the
-legs is very striking (Fig. 29). There is also a great difference in
-their method of progression through the water. Dytiscus moves both legs
-simultaneously, while Hydrophilus walks rather than swims, moving one
-leg after the other.</p>
-
-<p>If we cannot collect this Beetle for ourselves&mdash;which we should
-endeavour to do, if possible&mdash;it may be bought of almost any dealer
-in what are called ‘aquarium requisites.’ But prices rule higher
-for Hydrophilus than for Dytiscus. Bateman says that this species
-is rarer than formerly, and that specimens cost from 1<i>s.</i> to
-2<i>s.</i> 6<i>d.</i> a pair, ‘according to the dealer and the season.’
-From this I gather that I must have gone to a shop where the prices
-were reasonable, for I have never paid more than 6<i>d.</i> for a
-Hydrophilus, and then have been allowed to pick out a male. At the same
-shop I have paid 2<i>d.</i> for Dytiscus.</p>
-
-  <div class="figcenter" id="i_051" style="width: 502px">
-     <img
-    class="p2"
-    src="images/i_051.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 29.</span>&mdash;Great Water Beetle. <i>a</i>, male;
-<i>b</i>, female; <i>c</i>, larva; <i>d</i>, pupa.</p>
-  </div>
-
-<p>In keeping this Beetle we shall need a larger vessel than was required
-for Dytiscus. (In both cases the aquarium should be covered, for if
-food be scarce, and sometimes for other reasons, both these<span class="pagenum" id="Page_52">[52]</span> Beetles
-may take to flight.) The aquarium should be well supplied with growing
-water-weed, but none that is choice or valuable should be put in, for
-in moving about over the weed the animal will damage almost if not
-quite as much as it eats. This difficulty can be easily got over by
-supplying it with anacharis, water-crowfoot, milfoil, or any other
-common plant that grows rapidly and is easily procurable.</p>
-
-<p>The only specimen that I have taken myself was captured a few miles
-north of London. It exhibited a strange instance of depraved appetite.
-In the large tank into which it was put were growing vallisneria,
-frog-bit, and water-crowfoot in plenty. These it was never seen to
-touch. The tank, at one time, had been used for newts, and floating
-on the surface was a piece of virgin cork. It had served the former
-inmates as a kind of island continent, and had never been removed. To
-the under side of this the Beetle would moor himself, head downwards,
-and nibble away, as if cork were the natural diet of a British Water
-Beetle.</p>
-
-<p>In a few days the Beetle died. It was put into spirit, and soon after
-became the subject of a post-mortem. But its strange diet was not the
-cause of its death, which was sufficiently accounted for by injuries
-inflicted before its capture, probably by a larval or an adult Dytiscus.</p>
-
-<p>It would be mere waste of time to go over this Beetle and describe it
-point by point, as was done with Dytiscus. If what was there written
-was of any value, readers will be able to apply for themselves the
-method laid down. There are, however, some points of difference to
-which it will be well to invite attention.</p>
-
-<p>It is a good plan to lay specimens of these Beetles<span class="pagenum" id="Page_53">[53]</span> side by side
-for comparison. Hydrophilus is the larger of the two; and differs in
-colour as well as in size. Its hue is black with an olive tinge; and
-in certain lights a blue-black metallic gloss may be seen on the outer
-margins of the wing-cases. These are marked with faint longitudinal
-lines, and each bears three rows of dots running in the same direction.</p>
-
-<p>The greater length and more slender build of the legs of Hydrophilus
-are at once apparent. There is also a marked difference in the tarsal
-joints of the fore-legs of the male. The disks and cup-like hairs of
-Dytiscus are absent in Hydrophilus, but in their stead the last joint
-bears a sub-triangular plate, studded on the inner surface with spines,
-which probably serve a similar purpose. A great deal of valuable
-information about organs of this kind and their functions will be
-found in chapter X of Darwin’s <i>Descent of Man</i>. Simmermacher’s
-paper<a id="FNanchor_13" href="#Footnote_13" class="fnanchor">[13]</a> should be consulted by all who have the opportunity. Our inch
-magnifier will show us these spines quite clearly; and also a curious
-little bunch of bristles, which Simmermacher says are probably organs
-of touch.</p>
-
-<p>It is a good plan to take Hydrophilus out of the water, and lay it upon
-its back, so that the difference between it and Dytiscus may be clearly
-seen. The Beetle should be handled carefully, for on the thorax is a
-kind of keel, ending in a sharp spine, which extends over part of the
-abdomen. This spine is free, and may easily wound the hands of those
-who do not watch the motions of the creature pretty carefully. The fore
-part of the abdomen and the thorax are covered with short<span class="pagenum" id="Page_54">[54]</span> close hairs,
-and when the Beetle is in the water these parts entangle a layer of
-air, which gives it the appearance of being covered with quicksilver.</p>
-
-<p>The two Beetles differ also in their method of exchanging impure for
-pure air. Dytiscus, as we have seen, takes in a fresh supply under
-its wing-covers behind; Hydrophilus takes in a fresh supply in front,
-employing for this purpose the antennae, which apparently do not
-function as feelers, as is generally the case.</p>
-
-<p>When Hydrophilus wants to take in a supply of pure air, it rises to
-the top of the water, slowly and deliberately. Unlike Dytiscus, it
-is never in a hurry. Then one of the antennae is pushed through the
-surface film, thus communicating with the air, which descends to the
-hair-covered thorax, whence it reaches the spiracles on the upper
-surface of the abdomen. To allow of this the wing-cases are slightly
-raised in front. The spiracles in Dytiscus are larger at the posterior
-end of the abdomen: in Hydrophilus the largest spiracles are in front.
-This is what might be expected, from the method adopted in each case
-for procuring a fresh supply of air.</p>
-
-<p>These Beetles have frequently bred in confinement; but no better
-account than that of Lyonnet has ever been given of the operation of
-the female in making her cocoon and depositing her eggs. As his account
-is not generally available, a condensed translation of it is inserted
-with his illustration.</p>
-
-  <div class="figcenter" id="i_055" style="width: 530px">
-     <img
-    class="p2"
-    src="images/i_055.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 30.</span>&mdash;Female Hydrophilus constructing a
-cocoon. (After Lyonnet.)</p>
-  </div>
-
-<p>Lyonnet<a id="FNanchor_14" href="#Footnote_14" class="fnanchor">[14]</a> wanted to find out how the female made the cocoons (Fig.
-30), and this is how he set to work. He put some of these Beetles into
-a<span class="pagenum" id="Page_55">[55]</span> large aquarium, with a good quantity of water and some duckweed.
-On May 31 and the following day he noticed that one of the females
-was swimming about in every direction, as if in search of<span class="pagenum" id="Page_56">[56]</span> something.
-Thinking that this was because she had not the proper materials for her
-work, he then put into the aquarium some thread-like alga of a kind
-which he had seen attached to some cocoons, and on June 3 the Beetle
-began to make a cocoon, but soon gave up the task, apparently because
-she was troubled by other aquatic insects which had made a home in this
-weed. These intruders were removed, and the Beetle set to work once
-more. Lyonnet then noticed that, like a spider, she had her spinning
-apparatus at the posterior end of the body. She extended the last
-segments slightly, and opened the hindmost one, when he saw a nearly
-circular opening, in which was a whitish disk (Fig. 30<span class="allsmcap">A</span>,
-<i>a</i>). On this disk were two little brown tubercles side by side,
-nearly at right angles to the longitudinal axis of the body. From each
-there projected a blackish-brown conical tube, about a line long, stiff
-towards the base, but flexible and elastic towards the tip. These tubes
-were the spinnerets, which acted together with a parallel movement, and
-from each proceeded a separate thread.</p>
-
-<p>And this is how she made her cocoon. She lay near the surface of the
-water back downwards, the under part of the body and the second and
-third pair of legs buried in the thread-like weed. The front legs were
-free, and with these she shaped the weed over her abdomen. Then she
-spun a covering of white silk against the under side of the weed. While
-she was spinning, from time to time she used her front legs to press
-and flatten the work against her body (Fig. 30<span class="allsmcap">B</span>), giving it
-the shape of a flattened arch, to which her body gave the requisite
-curve. This, forming the top of the cocoon, was finished in about half
-an hour. Then she turned (Fig. 30<span class="allsmcap">C</span>), and spun<span class="pagenum" id="Page_57">[57]</span> the bottom of
-the cocoon, moulding this, like the top, on the curve of her abdomen,
-and uniting the top and bottom with silk which she spun. The work
-occupied about an hour and a quarter.</p>
-
-<p>The Beetle then remained nearly in that position for some two hours. At
-first she was hidden in the cocoon quite up to the thorax. The body,
-however, was withdrawn almost imperceptibly. During this time she was
-busy laying her eggs in regular order, with the pointed ends upwards.</p>
-
-<p>After this she came out of the cocoon, and closed the mouth (Fig.
-30<span class="allsmcap">D</span>), making the opening smaller by degrees. Then she made a
-little mast (Fig. 30<span class="allsmcap">D</span>, <i>b</i>), of the use of which Lyonnet
-admits his ignorance, suggesting, however, that its construction may
-serve to use up the silky matter remaining after the work is finished,
-lest it should acquire harmful qualities in the body of the Beetle. The
-true explanation seems to be that it serves to convey air to the eggs
-inside the cocoon.</p>
-
-<p>On July 17 Lyonnet was rewarded for his patient watching by seeing
-a larva come out of the cocoon, and the next day some fifty more
-appeared. What he saw and recorded it is in the power of others to see,
-if they will imitate his patient observation.</p>
-
-<p>The Cocktail Beetle, or Devil’s Coach Horse (<i>Ocypus olens</i>), is
-an excellent specimen of a Land Beetle to examine, for it is of fairly
-large size and extremely common. Moreover it does well in captivity, so
-that there will be no difficulty in watching its habits in life, and
-pickling it for closer examination when dead.</p>
-
-<p>During the day these animals usually lie concealed under stones or
-pieces of earth, coming forth at dusk and during the night in search
-of<span class="pagenum" id="Page_58">[58]</span> food. Occasionally, however, they may be met with in daylight,
-leisurely stalking a smaller beetle or a fly; then with a dash seizing
-the victim in their powerful mandibles, which are quite capable of
-making an impression on the human skin, as those who handle these
-Beetles unwarily will discover for themselves.</p>
-
-  <div class="figcenter" id="i_058" style="width: 550px">
-     <img
-    class="p2"
-    src="images/i_058.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 31.</span>&mdash;Cocktail Beetle. <i>a</i>, larva;
-<i>b</i>, pupa.</p>
-  </div>
-
-<p>Nothing of an animal nature comes amiss to them, and if they cannot
-capture living prey, they will make a hearty meal off carrion. This is
-an<span class="pagenum" id="Page_59">[59]</span> advantage to us, for we may feed our captives with dead insects or
-with small pieces of meat.</p>
-
-<p>This Beetle is about an inch long, and of a deep dull black colour.
-The head is joined to the thorax by a distinct neck, and the abdomen
-is naked, owing to the fact that the wing-cases are very short. Its
-wing-cases bear about the same proportion to those of the Margined
-Water Beetle that a man’s frock-coat bears to a boy’s Eton jacket. And
-this Beetle may be taken as a good type of a group&mdash;the Beetles with
-short wing-cases (<i>Brachel´ytra</i>).</p>
-
-<p>The attitude of this animal when irritated or alarmed is well depicted
-in Fig. 31. It raises its head menacingly and opens its strong
-mandibles to their full extent, at the same time turning up the end of
-the abdomen, like a scorpion about to sting. From the last segment it
-will often put forth a pair of white vesicles, from which is discharged
-a volatile liquid of disagreeable odour, that probably acts as a
-defence against insect-eating creatures.</p>
-
-<p>The best way to capture one of these Beetles is to pick it up with what
-Kirby calls the ‘natural forceps’&mdash;the finger and thumb. It may be
-dropped into any convenient receptacle; the small metal boxes in which
-vestas are sold will answer the purpose very well.</p>
-
-<p>My specimen was given me by a friend, who kept it with another in a
-round tin box. It lived with me for about three months in a four-ounce
-bottle, that measured three inches in height, to the neck, and two
-inches in diameter. The bottom was covered to the depth of about an
-inch with garden soil, and the top tightly corked, to prevent the
-prisoner’s escape. This precaution was necessary;<span class="pagenum" id="Page_60">[60]</span> for the inside of
-the bottle, though cleaned from time to time, soon became covered with
-a coating of earthy particles, which afforded the Beetle a pretty firm
-foothold.</p>
-
-<p>It was an extremely interesting pet, and its struggles to escape
-by climbing up the sides of the bottle often afforded me much
-entertainment. It seemed to have a glimmering notion that the only
-way out was by the top, and knowing nothing of the cork it would rear
-itself up against the side, and try to climb up by vigorous movements
-of its fore-legs. It would also take advantage of any little lump of
-earth projecting about the rest. It had not intelligence enough to make
-anything like a mound for itself, though the inequalities were probably
-the result of its burrowing under the surface. Its temper was none of
-the best, for if it was disturbed with the forceps it would resent it
-fiercely. The mandibles would be opened, the abdomen curled up, and out
-would come the two vesicles as a means of defence. If the forceps were
-put near the mandibles, they would be seized, and the Beetle would hold
-on so tenaciously that it has often been lifted out of its bottle in
-this fashion.</p>
-
-<p>It was exceedingly voracious, and was generally fed on garden worms.
-After a full meal its increase in size was very evident. This is not to
-be taken to mean that insects grow after they have attained the perfect
-or imago state, for this is not the case. But when they have had a long
-fast, the segments approach each other, and are forced apart when the
-creature is gorged with food. If a Beetle of this species were kept
-fasting for some days, and then carefully measured, and measured again
-after being plentifully supplied with worms or flies, there<span class="pagenum" id="Page_61">[61]</span> would be a
-difference of some millimetres between the results.</p>
-
-<p>Dallas has an interesting passage in his <i>Elements of Entomology</i>
-respecting the boldness of the larval form, which is worth quoting.
-‘I have seen one engaged in a struggle, which lasted about twenty
-minutes, with a worm of some five inches in length, the larva being
-scarcely more than an inch long. During this contest the little savage
-crept under the worm, fixing his mandibles into the creature’s body in
-various places, each bite apparently producing a considerable swelling.
-Sometimes he would fasten upon the head of the worm, and retain his
-hold with the pertinacity of a thoroughbred bulldog, although twisted
-about in every direction by the struggles of his intended victim. At
-last, however, he seemed to come to the conclusion that he had been
-too ambitious in his desires, and went quietly off amongst the grass,
-rather prematurely, as it seemed to me, for when the worm began slowly
-to leave the field of battle, about an inch of his tail was attached to
-the rest of his body solely by the intestine, a union which the jaws of
-the larva would easily have dissolved.’</p>
-
-<p>I have never seen a fight between a larva and a worm, for the few larva
-I have kept have been fed on flies. But the adult Beetle which has once
-fastened on a worm cannot be shaken off. It will grip its prey with the
-first pair of legs, fixing the claws in the skin, and will finish a
-worm three inches long at a meal.</p>
-
-<p>A dead specimen should be looked over in the way recommended for
-Dytiscus, raising the small wing-covers and unfolding the wings. The
-spiracles are to be looked for at the sides of the abdomen, in the
-groove formed by the meeting of the upper<span class="pagenum" id="Page_62">[62]</span> and under plates of each
-segment. The short downy hair with which the body is covered should
-be noticed, and the front legs are well worth examination. The tibia
-or shank is armed with a strong spine, and between this part of the
-leg and that which follows it is a notch, through which the Beetle
-passes its antennae to clean them from dirt. The peculiar shape of
-the joints of the tarsus or foot is very plainly discernible with the
-appliances at our command, and by a careful management we may make out
-the different kinds of hairs with which four out of the five of these
-joints are furnished; some stout and spine-like, others finer, ending
-in a pear-shaped bulb. These last probably serve the same purpose as
-the sucking-disks of Dytiscus and the tarsal plates of Hydrophilus.</p>
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_63">[63]</span></p>
-
-<h2>CHAPTER III<br />
-<span class="subhed">COCKROACHES; EARWIGS; THE GREAT GREEN GRASSHOPPER; THE WATER
-SCORPION; THE WATER BOATMAN; CORIXA.</span></h2></div>
-
-<div>
-<img class="drop-cap" src="images/i_063.jpg" width="50" alt=""  />
-</div>
-
-<p class="drop-cap p-left">The next insect to come within range of our pocket lens is the Common
-Cockroach (<i>Blatta orienta´lis</i><a id="FNanchor_15" href="#Footnote_15" class="fnanchor">[15]</a>), popularly misnamed the
-Black Beetle. We shall have no difficulty in procuring material for
-examination. Housekeepers will tell us that these creatures are only
-too plentiful.</p>
-
-<p>In the last chapter we dealt with Sheath-winged Insects&mdash;the
-Coleop´tera. Cockroaches belong to the Orthop´tera, or Insects with
-Straight Wings. The mouth-parts resemble those of Beetles. The chief
-differences that mark off the Cockroaches and their kin from the
-Beetles are the incomplete metamorphosis which the former undergo, and
-the character of the wings. Straight-winged Insects, when they leave
-the egg, differ little in shape from the adult, except in the fact that
-they have no wings; and these appendages are absent, or so small as
-to be useless for flight in many species. When wings are present the
-first pair are of little or no use for flight. They are not, however,
-hard<span class="pagenum" id="Page_64">[64]</span> chitinous sheaths, meeting in the middle line&mdash;that is, straight
-down the centre of the back&mdash;but of a flexible leathery or membranous
-substance, and they usually overlap each other at the tips. The hinder
-wings are large and nearly semicircular. The principal veins radiate
-from the centre to the circumference, like the sticks of a fan, and
-when the wings are folded up they lie straight along the upper surface
-of the abdomen. It is from this fact that the Order derives its name.</p>
-
-<p>There are two great groups, or sections, of Straight-winged
-Insects&mdash;those that run, like the Cockroaches, and those that leap,
-like the Grasshoppers. No Straight-winged Insect is aquatic.</p>
-
-<p>The Common Cockroach, now so abundant, is not a native, but an
-importation from Asia; though how it reached this country is not quite
-certain, probably by way of Holland. It seems to have established
-itself in London by the end of the sixteenth century, and some two
-hundred years later we find Gilbert White recording (in or before 1790)
-that ‘a neighbour complained that her house was overrun with a kind of
-black beetle, or, as she expressed herself, with a kind of black-bob,
-when they got up in the morning before daybreak. Soon after this
-account I observed an unusual insect in one of my dark chimney closets,
-and find since, that in the night they swarm also in my kitchen....
-The male is winged, the female is not, but shows something like the
-rudiments of wings, as if in the pupa state.... They are altogether
-night insects, <i>lucifugae</i>, never coming forth till the rooms are
-dark and still, and escaping away nimbly at the approach of a candle.’</p>
-
-<p>This description leaves no doubt as to what the ‘black-bobs’ really
-were. This name seems to<span class="pagenum" id="Page_65">[65]</span> have dropped out of use, and it would be well
-if ‘black beetle,’ in the sense of Cockroach, were also allowed to
-drop, for the term contains just as many errors as words.</p>
-
-<p>We may make our first acquaintance with these insects by keeping some
-specimens in confinement. A tin box, with a glass lid, will make a
-capital dwelling for them. Some paper should be put in, for them
-to hide in away from the light, and there can be no difficulty in
-providing them with food. ‘Bark, leaves, the pith of living cycads,
-paper, woollen clothes, sugar, cheese, bread, blacking, oil, lemons,
-ink, flesh, fish, leather, the dead bodies of other cockroaches,
-their own cast skins and empty egg-capsules, all are greedily
-consumed. Cucumbers, too, they will eat, though it disagrees with them
-horribly<a id="FNanchor_16" href="#Footnote_16" class="fnanchor">[16]</a>.’</p>
-
-<p>We have Dr. Sharp’s authority for the statement that in confinement
-these insects are rather amusing pets, as they ‘occasionally assume
-most comical attitudes, especially when cleaning their limbs. This they
-do somewhat after the fashion of cats, extending the head as far as
-they can in the desired direction, and then passing a leg or an antenna
-through the mouth; or they comb other parts of the body with the spines
-on the legs, sometimes twisting and distorting themselves considerably
-in order to reach some not very accessible part of the body<a id="FNanchor_17" href="#Footnote_17" class="fnanchor">[17]</a>.’</p>
-
-<p>The prejudice against these insects is, however, so strong, that most
-people will prefer to examine dead rather than living specimens, on
-account of the disagreeable odour of the latter. This odour is due to
-a fetid excretion from the mouth, and if<span class="pagenum" id="Page_66">[66]</span> the specimens are killed by
-dropping them into boiling water, this will be discharged, and after a
-little while they may be taken out with a pair of forceps, and put into
-spirit for preservation. If they are dropped alive into spirit, the
-excretion will communicate its strong scent to the preserving medium,
-and this should be changed before the insects are examined.</p>
-
-<p>From Fig. 32 we may get a general idea of the appearance presented by
-a male or female, lying back upwards in a small glass dish, ready for
-examination with the pocket lens. The female may be distinguished at a
-glance by her wingless condition&mdash;only rudiments of wing-cases being
-present, and no wings&mdash;and her broader abdomen. In life she does not
-stand so high upon her legs as does the male, and her abdomen trails
-along the ground. The male does not acquire his wings till the last
-moult.</p>
-
-  <div class="figcenter" id="i_066" style="width: 550px">
-     <img
-    class="p2"
-    src="images/i_066.jpg"
-     alt="" />
-     <p class="p0 sm center"><i>Female.</i><span style="margin-left: 12em"><i>Male.</i></span></p>
-     <p class="p0 sm center"><span class="smcap">Fig. 32.</span>&mdash;Cockroaches.</p>
-  </div>
-
-<p>As the Cockroach lies back uppermost in a glass dish, the head is
-almost concealed. This is<span class="pagenum" id="Page_67">[67]</span> especially the case, unless the insect is
-flattened out in some way, or pinned down to a piece of weighted cork.
-There will thus be, apparently, two, instead of three main divisions.
-This arises partly from the fact that the head is deflexed, or bent
-down so that the mouth is turned towards the rear, and partly because
-the first segment of the thorax bears a chitinous shield, roughly
-semicircular, which covers so much of the head as would otherwise be
-visible.</p>
-
-<p>The difficulty, however, may be easily got over, by reversing the
-position of the insect, and raising the head with a needle. The
-antennae will attract attention by their great length. In the male
-insect they exceed, while in the female they fall a little short of,
-the total length of the body. They are well worth examination. Even a
-low power will show that they consist of a number of joints&mdash;usually
-from seventy-five to ninety. The three basal joints are much larger
-than the rest, and in the female the third basal is nearly as long as
-the first. All these joints are thickly set with stiff hairs directed
-forwards. At the outer side of each antenna is a compound eye, and on
-the inner side is a pale spot, the <i>fenestra</i>, which in the males
-of some foreign Cockroaches is replaced by a simple eye.</p>
-
-<p>If Cockroaches are kept in confinement, and forced out into the light,
-the constant motion of the antennae will satisfy the observer that they
-are of great use to their owners. By means of these organs they not
-only discover their food, but become by some means, probably by the
-motion of air-waves, aware of danger that threatens them. Belt, in his
-<i>Naturalist in Nicaragua</i> (p. 110), speaking of the Cockroaches
-that infest houses in<span class="pagenum" id="Page_68">[68]</span> the tropics, says, ‘They are very wary, as they
-have numerous enemies&mdash;birds, rats, scorpions, and spiders; their long,
-trembling antennae are ever stretched out, vibrating as if feeling the
-very texture of the air around them; and their long legs quickly take
-them out of danger.’ It is not given to every one to visit the tropics,
-but we may all use our eyes in observing the common insects that abound
-in our country, and in doing this we shall strengthen the habit of
-observation, and very often find confirmation of what we read of the
-habits of insects in distant lands.</p>
-
-<p>Sir John Lubbock<a id="FNanchor_18" href="#Footnote_18" class="fnanchor">[18]</a>, in treating of the sense of smell in Insects,
-says that ‘Plateau put some food of which cockroaches are fond on a
-table, and surrounded it with a low circular wall of cardboard. He then
-put some cockroaches on the table: they evidently scented the food,
-and made straight for it. He then removed their antennae, after which,
-as long as they could not see the food, they failed to find it, even
-though they wandered about quite close to it.’</p>
-
-<p>The large kidney-shaped compound eyes are sure to attract attention.
-It is worth while to take out and break up an eye, gently washing out
-the pigment. If we do this, and then examine it with the pocket lens,
-we shall have some idea of the multiplicity of lenses in the eye of a
-Cockroach, each of the six-sided facets being a lens.</p>
-
-<p>Next come the mouth parts, which may be run over very quickly, for
-those of Beetles are formed upon the same plan, and from this primitive
-plan are derived the mouth parts of all other Insects, of whatever
-character they may be. To examine the<span class="pagenum" id="Page_69">[69]</span> mouth organs the insect must be
-turned on its back, and the <i>labrum</i> (<i>a</i>), or upper lip,
-raised with a needle, so as to allow of a general view of the rest.
-Then the jaws or mandibles (<i>b</i>) may be picked out with a needle.
-These jaws are strongly toothed, and work from side to side, and it
-is easy to see that they are very efficient organs. The lower jaws
-(<i>c</i>), or <i>maxillae</i>, lie below, and are compound organs,
-each being made up of several parts&mdash;the base, called the <i>cardo</i>
-or hinge (not shown in the illustration, but connected at right angles
-by a joint with the lower part, the <i>stipes</i>). From the stipes
-rise the <i>galea</i>, or helmet, on the outer side; and, on the
-inner side, the <i>lacinia</i>, to which the name maxilla is often
-applied, though it properly belongs to the whole. At the base of the
-<i>galea</i> is inserted the five-jointed maxillary palp, thickly set
-with hairs, and probably an organ of touch.</p>
-
-  <div class="figcenter" id="i_069" style="width: 428px">
-     <img
-    class="p2"
-    src="images/i_069.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 33.</span>&mdash;Mouth parts of a Cockroach.</p>
-  </div>
-
-<p>By examining the maxillae (<i>c</i>) before they are separated, and
-comparing them with the <i>labium</i> (<i>c</i>) or under lip, which
-closes the mouth from below, it will be evident that there is no
-slight similarity between them. Nor is this strange: for the under lip
-consists of the second maxillae joined at their bases, which form the
-<i>submentum</i> (<i>s</i>) and <i>mentum</i> (<i>m</i>). (The former
-is the small, the latter the large white basal portion; the vertical
-line in the illustration shows the mental suture, and should be<span class="pagenum" id="Page_70">[70]</span>
-traced in the dead insect.) The organs in the centre constitute the
-<i>ligula</i>; and on each side of the labium is a three-jointed palp
-(<i>labial</i>), like that on the maxillae, thickly set with hairs, and
-with a similar function. It is well to work over the mouth parts a few
-times till the relation between the maxillae and the labium is seen and
-understood. The internal tongue (<i>d</i>) is attached to the inner
-side of the labium.</p>
-
-<p>Now, still working on the under side of the insect, the three segments
-of the thorax are to be made out, and one cannot fail to notice the
-great size of the first joint (the <i>coxa</i>) in all the legs, and
-that these joints seem to serve as shields to protect the under side
-of the thorax. Then the different parts of the legs should be traced,
-and compared with Fig. 23 on p. 44. The spiny armature of the tibiae is
-to be noticed, as are the claws, between which is a projecting lobe,
-though this is absent in immature specimens. We shall find that the
-appendages of the thorax are the same as in the Margined Water Beetle.
-It is well to take as little as possible on trust, and to verify
-everything that we possibly can.</p>
-
-<p>Now we may reverse the position of our subject, and having cut off
-the wing-cases, which are technically called <i>teg´mina</i>, examine
-the wings. These may be gently unfolded with a needle or a camel’s
-hair brush, when the longitudinal method of folding will be clearly
-seen, and the difference of the veining from that of the wings of
-the Margined Water Beetle will be apparent. A female should also be
-examined, and the small tegmina cut off, so as to see that not even the
-rudiments of wings are present.</p>
-
-<p>The Cockroach breathes like other adult Insects, and the spiracles
-are ten in number&mdash;two on the<span class="pagenum" id="Page_71">[71]</span> thorax and eight on the abdomen. The
-thoracic spiracles may be pretty readily seen, but those on the abdomen
-are not so easy to make out. But by cutting away, with a fine pair
-of scissors, the edges of the plates that cover the upper and under
-surfaces of the abdomen and the membrane that unites them (Fig. 34), we
-may discover them as the open ends of small tubes. While dealing with
-the insect in this fashion, it will be easy to take out a piece of the
-tracheal tube, which may be compared with Fig. 28.</p>
-
-  <div class="figcenter" id="i_071" style="width: 350px">
-     <img
-    class="p2"
-    src="images/i_071.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 34.</span>&mdash;Cockroach, showing Spiracles.</p>
-  </div>
-
-<p>The abdomen consists of a series of rings or segments, the exact number
-of which is rather difficult to decide, from the fact that some are
-concealed and others altered in form. Dr. Sharp<a id="FNanchor_19" href="#Footnote_19" class="fnanchor">[19]</a> says that ‘it is
-considered that ten dorsal and ten ventral plates exist, though the
-latter are not so easily demonstrated as the former.’ In the male, ten
-above (dorsal) and nine below (ventral), and in the female two less in
-each case, may be made out without dissection.</p>
-
-<p>From the sides of the tenth segment two organs, the <i>cerci</i>
-(Fig. 35, <i>a</i>), are given off, one on each side. These may be
-distinguished from the styles of the males by their presence in both
-sexes. Our inch lens will show that each cercus consists of sixteen
-rings. If we use the half-inch, we shall see that each ring is set with
-hairs of different lengths.</p>
-
-<p>When we have got so far it may be well to compare the structure of
-a <i>cercus</i> with that of an<span class="pagenum" id="Page_72">[72]</span> antenna (p. 67). In each we have a
-succession of jointed rings giving flexibility to the organ, and the
-rings in each case are studded with hairs. It has been shown pretty
-conclusively&mdash;and we may verify the experiments&mdash;that the antennae are
-sense-organs. Are we not justified in coming to the conclusion that,
-since the antennae and the cerci resemble each other in structure,
-they also resemble each other in function? If the Cockroach receives
-sensations by means of the antennae, is it not probable that it also
-receives sensations by means of the cerci?</p>
-
-<p>Having worked over the Cockroach from the outside, it will be
-advantageous to get some acquaintance with its internal anatomy.
-This is not a difficult matter. The specimen is to be pinned down,
-under water, with its back uppermost. The wings having been removed,
-a longitudinal cut is to be made down the centre from the posterior
-part of the abdomen to the back of the head, and the two sides of the
-integument turned back. Or the junction between the upper and lower
-plates on each side may be cut through with a cutting needle, and the
-whole integument removed.</p>
-
-<p>The first task is to clear away the fat-body, a whitish substance
-which overlies the chief organs of the body. When this is picked to
-pieces and floated off the digestive system will be exposed. After
-this has been worked over a few times there should be no difficulty in
-dealing with similar parts in other Insects. At the back of the head
-lies the gullet or oesophagus leading into the crop (<i>c</i>), at the
-base of which lies the gizzard (<i>g</i>). The interior of this organ
-is furnished with six strong chitinous teeth, with small ridges of
-the same substance between them. Towards the posterior end<span class="pagenum" id="Page_73">[73]</span> are six
-cushions, all set with fine bristles. Behind this comes the stomach
-(<i>v</i>), into which open seven or eight tubes, closed at one end,
-and between it are the Malpighian tubes, which are concerned in the
-process of excretion. The small intestine (<i>co</i>) succeeds, and
-behind this is the rectum (<i>r</i>).</p>
-
-  <div class="figcenter" id="i_073" style="width: 246px">
-     <img
-    class="p2"
-    src="images/i_073.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 35.</span>&mdash;Alimentary Canal of Cockroach.</p>
-  </div>
-
-<p>It will be interesting to separate the gizzard from the crop (<i>c</i>)
-and stomach (<i>v</i>) and break it open with a couple of needles, so
-as to examine the teeth, which will be more easily made out if the
-opened organ be allowed to soak for a time in a solution of caustic
-potash.</p>
-
-<p>Similar teeth-like<span class="pagenum" id="Page_74">[74]</span> processes are found in the gizzards of many other
-Insects, and their presence has given rise to some strange ideas.
-Swammerdam<a id="FNanchor_20" href="#Footnote_20" class="fnanchor">[20]</a> says, ‘I preserve also the threefold stomach of a
-locust, which is very like the stomach of animals that chew the cud,
-and particularly has that part of the stomach called Echinus<a id="FNanchor_21" href="#Footnote_21" class="fnanchor">[21]</a> very
-distinctly visible. I do not, therefore, doubt but locusts chew the
-cud, as well as the animals just mentioned. Indeed, I persuade myself
-that I have seen this.’</p>
-
-<p>Somewhat similar teeth-like processes exist in the Lobster, the Crab,
-and the Crayfish. ‘Professor Plateau has expressed a strong opinion
-that neither in the stomach of Crustacea nor in the gizzard of Insects
-have the so-called teeth any masticatory character.’ He adopts
-Swammerdam’s comparison, but considers them strainers, not dividers of
-the food<a id="FNanchor_22" href="#Footnote_22" class="fnanchor">[22]</a>.</p>
-
-<p>We may be fortunate enough to meet with some specimens of the American
-Cockroach (<i>Periplane´ta america´na</i>, Fig. 36), a much larger
-species, which has established itself in some few places in this
-country. At the Zoological Gardens, Regent’s Park, it is abundant, and
-has almost, if not entirely, driven out the common form. Mr. Bartlett
-believes that it was introduced in cases in which animals have been
-sent over from America. Both sexes are winged. They not only possess
-organs of flight, but use them. If one visits the Gardens, there will
-be no difficulty in getting specimens; and it is interesting to compare
-the points of<span class="pagenum" id="Page_75">[75]</span> agreement in and of difference between this animal and
-our common form.</p>
-
-  <div class="figcenter" id="i_075" style="width: 472px">
-     <img
-    class="p2"
-    src="images/i_075.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 36.</span>&mdash;American Cockroach (male).</p>
-  </div>
-
-<p>The Earwig (<i>Forfic´ula auricula´ria</i>) is common enough to furnish
-us with plenty of specimens on which we may employ our pocket lens. Any
-garden in the summer months will yield an ample supply. Earwigs, like
-Cockroaches, are light-shunning insects, and love to hide themselves in
-the corollas of flowers; and it is probably from their habit of seeking
-to conceal themselves that they have acquired their bad reputation&mdash;by
-no means confined to our own country&mdash;of creeping into the ears of
-persons lying asleep, and causing death by getting into the brain. Such
-an occurrence is beyond the bounds of possibility. No insect of this
-size could pass the drum of the ear.</p>
-
-<p><span class="pagenum" id="Page_76">[76]</span></p>
-
-<p>We may easily keep these insects and observe their movements, if we
-put them into a wide-mouthed glass bottle and supply them with food.
-They are extremely fond of the flowers of the dahlia; but a dahlia
-would offer too many hiding-places, so we will put into the bottle some
-nasturtium flowers, or any others with a bell-shaped corolla.</p>
-
-<p>If we get a colony in spring we may watch the care of the female for
-her eggs. According to Kirby and Spence<a id="FNanchor_23" href="#Footnote_23" class="fnanchor">[23]</a>, ‘she absolutely sits
-upon her eggs, as if to hatch them&mdash;a fact which Frisch appears first
-to have noticed&mdash;and guards them with the greatest care. De Geer
-(<i>Mémoires</i>, iii. 548) having found an earwig thus occupied,
-removed her into a box where was some earth, and scattered the eggs in
-all directions. She soon, however, collected them one by one, with her
-jaws, into a heap, and assiduously sat upon them as before. The young
-ones, which resemble the parents, except in wanting elytra and wings,
-... immediately upon being hatched creep like a brood of chickens
-under the belly of the mother, who very quietly suffers them to push
-between her feet, and will often, as De Geer found, sit over them in
-this posture for some hours.’ Mr. Kirby adds: ‘This remarkable fact I
-have myself witnessed, having found an earwig under a stone which I
-accidentally turned over, sitting upon a cluster of young ones, just as
-this celebrated naturalist has described.’</p>
-
-<p>Like the Cockroaches, Earwigs undergo an incomplete metamorphosis.
-When the young leave the egg they resemble their parents, as may be
-seen from the immature forms represented in<span class="pagenum" id="Page_77">[77]</span> Fig. 37. The resemblance
-becomes greater at each successive moult.</p>
-
-  <div class="figcenter" id="i_077" style="width: 322px">
-     <img
-    class="p2"
-    src="images/i_077.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 37.</span>&mdash;Larva and Pupa of Earwig.</p>
-  </div>
-
-<p>In working over these insects, the forceps, or pincers, at the end
-of the abdomen will attract attention. They are found throughout the
-family, but little is known of their function. It is said that they
-are used to aid in folding the wings, and tucking them under the
-wing-covers. This can scarcely be their only function, for they are
-found in species that have no wings. Probably they serve as organs
-of defence and, to some slight extent, of offence. When the abdomen
-is curled up, these forceps certainly give the insect a threatening
-appearance. They cannot, however, do much harm.</p>
-
-<p>These forceps differ in shape in the male (Fig. 38) and female, the
-blades being almost close together in the latter. In the males they
-differ considerably in size. Of 583 mature males taken in one day in
-the Farne Islands, and examined by Messrs. Bateson and Brindley, the
-forceps varied in length from 2·5 mm. to 9 mm.<a id="FNanchor_24" href="#Footnote_24" class="fnanchor">[24]</a> These are called
-respectively ‘low’ males and ‘high’ males. The latter are in all points
-larger than the former, and have been described as a separate species,
-‘but it was impossible to get reliable measurements of the total
-length, owing to the fact that the abdominal segments telescope into
-each other’ (cf. p. 30).</p>
-
-<p>After examining the antennae and dissecting out the mouth organs, the
-peculiar overlapping or imbrication<span class="pagenum" id="Page_78">[78]</span> of the plates of the abdomen
-should be looked for; and on the membrane that connects them the
-spiracles may be detected.</p>
-
-<p>The wings and the complex method of folding have led some systematists
-to rank the Earwigs as an Order, while some others rank them as a
-Sub-order. For the present, at any rate, we need not concern ourselves
-about this. It is enough for us to know that they are closely related
-to the Orthop´tera.</p>
-
-<p>As we look at the Earwig from above, the wing-cases recall to our mind
-those of the Devil’s Coach Horse (Fig. 31), though there is one great
-difference. From beneath those of the Earwig project two small leathery
-pieces which are absent in the Beetle. These pieces are not, as one
-might imagine, at the tips of the wings, but on the front margin, about
-halfway down, and is indicated in the illustration by the shading
-between the extremity of the wing-case and the crease-mark at <i>a</i>.</p>
-
-  <div class="figcenter" id="i_078" style="width: 350px">
-     <img
-    class="p2"
-    src="images/i_078.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 38.</span>&mdash;Earwig (male).</p>
-  </div>
-
-<p>From the illustration we may understand how the Earwig opens and closes
-its wings. From the point <i>a</i> veins, which are thickened about
-halfway down, radiate to the hinder edge of the wing, and a little
-beyond the thickening they are connected by a vein which runs parallel
-with the hinder edge. These radiating veins are brought together, so
-that there is a fan-like closing, like<span class="pagenum" id="Page_79">[79]</span> that of the Cockroach, but from
-a different centre. The wing is then folded back at the place where the
-veins are thickened, and then there is a second transverse fold at the
-point <i>a</i>, so that the only part of the wing now visible is the
-leathery patch, which projects beyond the wing-case when the wing is
-tucked away.</p>
-
-<p>It is not difficult to unfold the wing of a dead specimen, under water,
-using a needle and fine brush. Mr. E. A. Butler<a id="FNanchor_25" href="#Footnote_25" class="fnanchor">[25]</a> recommends a simple
-but excellent plan for unfolding and preserving the wing, by gumming
-it, with the upper surface downwards, to a piece of card, and gradually
-unfolding it and fastening it down. This is not so easy as it may seem,
-but with patience and perseverance success will be obtained; and a
-similar method may be adopted with the wings of other Insects, which
-may be mounted in this way without any trouble. Thus they may be easily
-preserved for examination at a future time, or for comparison with the
-wings of other Insects.</p>
-
-<p>It is rather remarkable that an insect like the Common Earwig, which
-very rarely takes to flight, should have such a complex method of
-folding its wings. Dr. Sharp says that though the Earwig ‘is scarcely
-surpassed in numbers by any British insect, yet it is rarely seen on
-the wing. It is probable that the majority of individuals of this
-species may never make use of their organs of flight, or go through the
-complex process of folding and unfolding them.’</p>
-
-<p>Let us choose our next example from the Leaping Orthop´tera. They may
-be distinguished at a glance from their relatives that run, but do not<span class="pagenum" id="Page_80">[80]</span>
-leap, by the peculiar structure of the third pair of legs. These are
-much longer and stouter than the other two pairs, and the thigh is very
-muscular. This insect is a very good type of the family Locus´tidae, to
-which, however, none of the insects popularly called ‘locusts’ belong.
-They are included in another family (<i>Acridi´idae</i>), where the
-common British Grasshoppers are also placed. The Locustids and the true
-locusts may be distinguished by the difference in their antennae: in
-the latter these organs are short, in the former they are very long and
-delicate.</p>
-
-<p>The Great Green Grasshopper (<i>Locus´ta viridis´sima</i>) (Fig. 39) is
-fairly common all over the country, but often escapes observation from
-the fact that its hue corresponds so nearly to that of the foliage on
-or among which it lives. One specimen taken in a Devonshire lane gave
-me a great deal of trouble before it was secured and transferred to
-a small tube. It was perched on a leaf when I first saw it, and as I
-approached it leaped away. Though I was certain it had not gone far,
-it was some little time before I discovered it, and got near enough
-to grasp leaf and insect, in time to prevent the latter from taking
-another jump.</p>
-
-<p>This insect may be kept alive in confinement for a considerable time,
-and will do fairly well on a diet of leaves and fruit, though it will
-not refuse an occasional meal of flesh. Dr. Sharp says that a specimen
-in confinement ‘mastered a humble-bee, extracted with its mandibles
-the honey-bag, and ate this dainty, leaving the other parts of the
-bee untouched.’ It is said that if two be placed together in a box
-they will fight most desperately, and that the victor will make a meal
-off the body of its victim. De Geer witnessed a case of this<span class="pagenum" id="Page_81">[81]</span> kind in
-a closely allied species that is found in Sweden. Its specific name
-signifies ‘wart-eater,’ and commemorates the fact that the peasants
-incite these insects to bite their warts, firmly believing that warts
-once bitten speedily disappear, and do not grow again. Westwood says
-that one of these insects actually devoured part of its own leg that
-had been broken off accidentally. When the creature was seen at night
-the detached leg was whole; in the morning about half of it had been
-eaten.</p>
-
-  <div class="figcenter" id="i_081" style="width: 500px">
-     <img
-    class="p2"
-    src="images/i_081.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 39.</span>&mdash;Great Green Grasshopper (female).</p>
-  </div>
-
-<p>It is well to get specimens of male and female insects. We shall
-require the former in order to examine the sound-producing apparatus,
-which the females do not possess; and the latter for the sake<span class="pagenum" id="Page_82">[82]</span> of the
-ovipositor&mdash;a long scimitar-like organ by means of which the eggs are
-deposited. Let us take the female first. The length, including the
-ovipositor, is a little under two inches, and the antennae will measure
-about as much more. The wing-cases do not lie flat upon the back, as do
-those of the Cockroach, but in a slanting position, like the sides of
-a roof, forming a ridge in the centre. The head is not bent back, as
-in the Cockroach, nor does it project in front, as in the Beetles, but
-the front is almost vertical. The armature of the mouth is strong, and
-of the same pattern as that of the Cockroach. The hood&mdash;so the upper
-covering of the thorax is called&mdash;is of a peculiar shape, somewhat like
-that of a saddle. The wing-cases and wings, with their folding, will
-offer little difficulty. Next we may examine the cerci, and contrast
-them with those of the Cockroach and with the forceps of the Earwig.
-Last of all, the ovipositor must be examined, and its structure made
-out, so far as the means at our command will allow.</p>
-
-<p>Apparatus of this kind for placing eggs in positions favourable to
-their development is by no means confined to these insects, for
-examples may be found in other Orders. Sirex, the so-called Tailed
-Wasp, has a long straight one, which is often supposed to be a sting,
-and the insect itself is not unfrequently taken for a gigantic wasp or
-hornet.</p>
-
-<p>When the ovipositor of our subject is looked at with the unassisted
-eye, it appears to consist of two curved blades placed side by side,
-with an internal groove on each. The apparatus, however, is not quite
-so simple: it is made up of six chitinous rods, of which four&mdash;the two
-above, and the<span class="pagenum" id="Page_83">[83]</span> two central ones&mdash;are developed from the ninth segment
-of the abdomen, while the two lower ones spring from the eighth. It is
-not difficult to test these statements. Specimens are plentiful; and as
-the ovipositor in this insect is large, and easily broken up into its
-component parts, it may well serve as an introduction to the study of
-these organs in other Insects&mdash;the Saw-flies, for example.</p>
-
-<p>When the insect is about to deposit her eggs, she selects a spot where
-the soil is light, and bending the ovipositor nearly at a right angle
-to her body, thrusts it into the ground as far as possible. Then, by
-a muscular effort, the plates of the ovipositor are separated, and
-several eggs travel down the passage formed by the central pair of rods
-into the hole. This is repeated time after time, till the operation of
-egg-laying is completed. This takes place in the autumn, and the young
-emerge from the eggs in the spring. When they come out they are tiny
-copies of the adults; but they do not acquire wings till after several
-months. The ovipositor of the female appears after the second moult,
-and till this organ is developed no difference is apparent between the
-young insects.</p>
-
-<p>The chief interest of the male insect lies in its wings, for the first
-pair (the <i>teg´mina</i>) are the organs with which it produces its
-‘love-songs.’ Kirby comments on the fact that Lichtenstein, in the
-<i>Linnaean Transactions</i> (iv. 51), ‘draws attention to the eye-like
-area in the right wing-case of the males of this genus,’ adding that
-that author seemed ‘not to be aware that De Geer had noticed it before
-him, as a sexual character; and also, with good reason, supposed that
-it assists these animals in the sounds they produce.’</p>
-
-<p>This is how De Geer (<i>Mémoires</i>, iii. 429) describes<span class="pagenum" id="Page_84">[84]</span> the
-sound-producing apparatus of the Great Green Grasshopper: ‘In our
-male grasshoppers, in that part of the right elytron which is folded
-horizontally over the trunk, there is a round plate of very fine
-transparent membrane, resembling a little mirror or piece of talc, of
-the tension of a drum. This membrane is surrounded by a strong and
-prominent nervure, and is concealed under the fold of the left elytron,
-which has also several prominent nervures answering to the margin of
-the membrane or ocellus. There is every reason to believe that the
-brisk movement with which the grasshopper rubs these nervures against
-each other produces a vibration in the membrane, augmenting the sound.
-The males in question sing continually in the hedges in the months of
-July and August, especially towards sunset, and part of the night. When
-any one approaches they immediately cease their “song.”’</p>
-
-<p>It is probably unnecessary to do more than remark that the noises made
-by Insects do not correspond to the voices of the higher animals. ‘For
-no insect, like the larger animals, uses its mouth for utterance of
-any kind: in this respect they are all perfectly mute; and, though
-incessantly noisy, are everlastingly silent<a id="FNanchor_26" href="#Footnote_26" class="fnanchor">[26]</a>.’</p>
-
-<p>Our plan with these wings is to first verify the fact of their bearing
-these talc-like spots, the serrated nervures on the right and the
-rudimentary file on the left elytron. The sound is produced by rubbing
-the base of the left elytron against that of the right. A recent author
-compares this insect to a fiddler, and says that the left tegmen is the
-bow and the right the fiddle.</p>
-
-<p><span class="pagenum" id="Page_85">[85]</span></p>
-
-<p>The last point to examine is the ear. It seems strange to say that
-these insects have ears in their legs; but though some of the older
-entomologists regarded these structures in the tibiae of the first pair
-of legs as nothing more than resonators or sound-boards to intensify
-their chirping, there is no doubt that they are really organs of
-hearing. Much interesting information on this subject will be found in
-Sir John Lubbock’s <i>Senses of Animals</i>.</p>
-
-  <div class="figcenter" id="i_085" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_085.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 40.</span>&mdash;Tibial ear of Great Green Grasshopper.</p>
-  </div>
-
-<p>These oval patches are plainly distinguishable by the unassisted eye,
-and correspond in function to the tympanum or drum of the human ear.
-The air-supply to the tibiae is distinct from that of the rest of the
-body, and is derived from a large orifice on each side of the first
-segment of the thorax. These orifices may be seen by removing the
-‘hood.’ Indeed, they cannot escape observation. From these orifices an
-air-tube passes to each leg, dividing into two branches in the tibia
-and reuniting below the drums.</p>
-
-<p>Dr. Sharp<a id="FNanchor_27" href="#Footnote_27" class="fnanchor">[27]</a> says that ‘although the tibial ears of the Locus´tidae
-are very perfect organs, there is great difficulty in deciding on the
-exact nature of their functions. They would appear to be admirably
-adapted to determine the precise locality from which a sound proceeds
-... for the legs can be moved in the freest manner in every direction,
-so as to bring the drum into the most direct line of the vibrations.
-But as to what kinds of vibrations may be perceived, and the manner
-in which they<span class="pagenum" id="Page_86">[86]</span> may be transmitted to the nerves, there is but little
-evidence.’</p>
-
-<p>The next Order from which we shall choose examples will be the
-Hemip´tera, containing the Land and Water Bugs and some other forms.
-Our chief concern, however, is with the Water Bugs. In this Order the
-metamorphosis is incomplete; the mouth is adapted for sucking the
-juices of plants and animals; and there are usually four wings. In the
-Land and Water Bugs, part of the fore wings is harder than the hind
-wings; in the other winged members of the Order both pairs of wings are
-membranous. The front wings are called hemel´ytra or halfel´ytra, to
-distinguish them from the el´ytra or wing-cases of Beetles, which are
-chitinous throughout. Fig. 41 shows the hemel´ytron and hind wing of a
-Land Bug, and the names given to the different parts of the front wing.</p>
-
-  <div class="figcenter" id="i_086" style="width: 450px">
-     <img
-    class="p2"
-    src="images/i_086.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 41.</span>&mdash;A Land Bug (magnified). <i>a</i>,
-corium; <i>b</i>, clavus; <i>c</i>, membrane.</p>
-  </div>
-
-<p>The Water Scorpion (<i>Nepa cine´rea</i>) is not difficult to procure,
-or to keep in confinement when it is caught. It would be straining
-language to call it a handsome creature, yet it well deserves careful
-study, on account of the wonderful modification of the first pair of
-legs, and it is from the resemblance of these to the pedipalps of the
-scorpion that the insect derives its popular name. Its length is<span class="pagenum" id="Page_87">[87]</span> about
-an inch and a quarter, from the tip of the beak, or rostrum, to the end
-of the breathing-tube. Its greatest width is a little over a quarter of
-an inch (Fig. 42). The general hue harmonizes well with the mud, but
-the upper surface of the abdomen is a warm red, ‘and is thick set with
-hair, so as to afford a very agreeable sight.’</p>
-
-  <div class="figcenter" id="i_087" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_087.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 42.</span>&mdash;Water Scorpion.</p>
-  </div>
-
-<p>It is extremely common in shallow pools, and its favourite haunt is
-near the shore, where it will lie, almost buried in the mud, with its
-raptorial legs elevated, ready to seize on any passing insect, and its
-breathing-tube just pushed through the surface-film. I learnt this
-habit of the insect on the first occasion on which I tried to collect
-specimens of it. I had been told that a certain piece of water swarmed
-with Water Scorpions. This, I afterwards found, was quite correct;
-but though I worked the pond from end to end, a single specimen was
-all that rewarded my labour. Whilst transferring the insect from the
-net-tube to the bottle for transport, a stranger joined me, and kindly
-volunteered his assistance. He had no collecting tackle, but in about
-a quarter of an hour he brought at least a dozen good specimens in the
-bottle he had borrowed.</p>
-
-<p>It was natural to inquire to what his success was due. He told me that
-it was his first attempt at collecting, but that just before joining
-me he had noticed the ends of the breathing-tubes sticking out of the
-water. This excited his curiosity, and on moving the mud with his
-walking-stick, the insects were seen to crawl away<span class="pagenum" id="Page_88">[88]</span> slowly. When he
-saw me transfer the Water Scorpion from the net-tube to the bottle, he
-immediately recognized it. Then he courteously offered his help, for
-which, of course, I was grateful.</p>
-
-<p>We may keep the Water Scorpion alive for a considerable time in a small
-bottle of water, in which is some growing weed. If we watch it moving
-about, we shall see that the front legs are used for locomotion as well
-as for seizing prey. Some authors doubt this. Any one may settle the
-question for himself, if he will put one of these insects into a small
-bottle with plenty of weed. Generally, however, the insect uses only
-the second and third pairs for walking, the first pair being raised and
-directed forward, with the tarsus bent at an angle (Fig. 42). Even when
-it does use its front legs for locomotion, the action is not that of
-walking; the insect employs these limbs to pull itself along in a sort
-of ‘hand-over-hand’ fashion, but on a level surface it uses the first
-pair in the same way as it does the other two pairs.</p>
-
-<p>Its habit of burying itself in the mud may also be watched with very
-little trouble. A common pudding-basin will make an excellent aquarium
-for this purpose. The bottom is to be covered with garden mould and
-vegetable <i>débris</i>, mixed with a few stones. The whole mass should
-be arranged unevenly, so that when water is added it may not form one
-sheet, but a series of small shallow pools. Very little duckweed will
-serve to keep it sweet. It only remains to drop in the Water Scorpion.
-Before long it will accommodate itself to its new surroundings, and so
-bury itself that it will be no easy task to discover it.</p>
-
-<p>An aquarium of the kind described stands at<span class="pagenum" id="Page_89">[89]</span> present on my
-writing-table. Many have been the inquiries as to what kind of creature
-lived therein; and more than one old hand at collecting has failed to
-find the insect. It is always safe to look round the sides of the basin
-for the breathing-tube; if it is not detected in this situation, a
-glance along the surface of the tiny pools will probably show a break
-in the film. The Water Scorpion will not be far off.</p>
-
-<p>That the insect really does cover itself with mud may be demonstrated
-by transferring it from the aquarium described to any shallow vessel,
-and allowing a fine stream of water&mdash;say, from a dipping-tube&mdash;to fall
-gently on it. The mud will be washed away, and in a few seconds will
-settle at the bottom.</p>
-
-<p>It is well to keep such an aquarium covered, for the Water Scorpion has
-no mean power of flight. A circular plate of glass, which may be bought
-for a few pence, makes the best cover, but a piece of fine muslin
-fastened round the rim of the basin will do. Swammerdam says, ‘These
-Water Scorpions live all the day in the water, out of which they rise
-about the dusk of evening into the air, and so flying from place to
-place, often betake themselves in quest of food to other waters.’ Then
-follows a deduction which shows how far he was in advance of his time:
-‘This affords us a satisfactory reason for the great number of insects
-that immediately appear in the smallest collections of water, since
-they may very well get thither when it is dark, so that the opinion
-which ascribes to putrefaction the power of forming insects, &amp;c., must,
-by this instance of the Water Scorpion’s nocturnal transmigrations,
-appear more and more frivolous and unnecessary.’</p>
-
-<p><span class="pagenum" id="Page_90">[90]</span></p>
-
-  <div class="figcenter" id="i_090" style="width: 394px">
-     <img
-    class="p2"
-    src="images/i_090.jpg"
-     alt="" />
-     <p class="p0 sm"><span class="smcap">Fig. 43.</span>&mdash;<i>A.</i> Water Scorpion. <i>a</i>, rostrum;
-<i>b</i>, wing-cases; <i>c</i>, wings; <i>d</i> <i>d</i>,
-second and third pairs of legs; <i>e</i>, raptorial legs (the
-first pair); <i>f</i>, spine forming breathing-tube; <i>g</i>,
-parasitic mite. <i>B.</i> Portion of an oviduct containing eggs
-(magnified). <i>C.</i> An egg (magnified). <i>D.</i> Parasitic
-mite. <i>a</i>, head; <i>b</i>, eyes; <i>c</i>, legs; <i>d</i>
-<i>d</i>, legs (seen from under surface). (After Swammerdam.)</p>
-  </div>
-
-<p>No larva or other animal that is of any value should be kept in the
-same aquarium with the Water Scorpion. Dr. Hill, who annotated the
-English edition of Swammerdam, says, ‘There is not perhaps in all the
-animal creation so outrageous or fierce a creature against those weaker
-than itself as the Water Scorpion. It destroys, like the wolf among
-sheep, twenty times as many<span class="pagenum" id="Page_91">[91]</span> as its hunger requires.’ The Rev. G. C.
-Bateman placed one in a saucer with a tiny minnow; ‘but no sooner did
-the little fish swim within reach of the fore-legs of the scorpion
-than it was seized by them, and pressed against the hungry creature’s
-rostrum.’ It seems to be particularly fond of Asellus, the water
-woodlouse. I have often taken dead specimens of this crustacean, sucked
-completely dry, from between the raptorial legs of the insect. One
-specimen was so thoroughly cleaned out that it was mounted just as it
-was, the only preparation being a brief soaking in spirit.</p>
-
-<p>In examining the head the eyes may be readily distinguished, and on
-pressing the rostrum or beak with a needle, the proboscis will be
-forced out, just as one may force out the sting by pressing the abdomen
-of a bee or a wasp. In this group the antennae are three-jointed and
-concealed. When one begins to look for these organs he will probably
-come to the conclusion that the concealment is highly effectual.</p>
-
-<p>A very simple method of finding them in a spirit specimen is to take
-the insect between the thumb and index finger of the left hand, holding
-it up to the light in such fashion as to keep the first pair of legs
-well clear of the head. Then, with a needle held in the right hand,
-raise the thorax till it lies in the same plane as the body. Each
-antenna lies in a groove beneath the eye. Gentle manipulation with the
-needle will lift them out, so that they may be clearly seen, not only
-with the hand magnifier, but with the unassisted eye. Or the insect may
-be pinned down under water instead of being held in the hand, and the
-antennae lifted or brushed out of the groove.</p>
-
-<p>It will greatly simplify matters if, before attempting<span class="pagenum" id="Page_92">[92]</span> to raise the
-wings, the fact is borne in mind that the tip of the right wing-case
-lies over that of the left. It is perhaps as well to remove the
-wing-case altogether by inserting a needle under it, and gently raising
-it, using a little pressure in an outward direction. It will then be
-quite time to raise the wing and to see the method of folding and
-unfolding.</p>
-
-  <div class="figcenter" id="i_092" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_092.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 44.</span>&mdash;Raptorial leg of Water Scorpion.</p>
-  </div>
-
-<p>In Fig. 44 we have a representation of the raptorial (front) leg
-of this insect. This leg should be compared with the legs of other
-Insects&mdash;not in pictures only, but in actual specimens&mdash;that we may see
-how, while the general plan is preserved, different joints are modified
-to suit the special function of this limb&mdash;that of taking prey. (See
-also Fig. 43.)</p>
-
-<p>The thigh (<i>f</i>) is the largest joint, for the obvious reason that
-it contains the muscles that work the tibia and tarsus, which together
-form a kind of knife-blade, shutting down into a groove in the thigh,
-which may very well be compared to the handle of a pocket-knife. This
-description, however, is not to be taken on trust. It is not enough
-to read about the groove: we must see it for ourselves, raise the
-‘knife-blade’ from the groove, and press it down again, and pass the
-needle along the groove. If we examine the interior of the groove, we
-shall find that there is a projection along the bottom, so that a cross
-section would appear like this&mdash;<img src="images/i_092a.jpg" alt=""
-style="height:1em; vertical-align: middle;" />. The inner portion of the
-tibia is also grooved; so that when once the prey is seized by this
-powerful limb, it has no chance of escape. The tarsus (<i>tar</i>)
-is not clearly distinguished from the<span class="pagenum" id="Page_93">[93]</span> tibia (<i>tib</i>) in the
-engraving, but it may be distinctly seen as a claw-like appendage in a
-living or dead specimen.</p>
-
-<p>The breathing-tube remains to be examined. It may be detached from the
-body for more convenient manipulation. When this is done, the tube will
-be seen to consist of two pieces, each grooved on the inner side and
-set with hairs, which, as they interlock, prevent the entrance of water.</p>
-
-<p>A somewhat similar arrangement occurs in the proboscis or tongue of
-butterflies. There is perhaps a closer parallel in the antennae of
-the masked crab, which, under certain conditions, form a kind of
-breathing-tube, each antenna being joined to its fellow by the hairs
-with which it is set.</p>
-
-<p>There are two other Water Bugs which lend themselves to our purpose
-very well. Each is popularly called Water Boatman, though that name is
-better confined to Notonecta, because the insects of this genus ‘row
-themselves about on their backs with their long feathered legs.’ In the
-United States they are called Water Cicadae, from the shrill noise they
-make, probably by rubbing the fore-legs together.</p>
-
-  <div class="figcenter" id="i_093" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_093.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 45.</span>&mdash;Water Boatman.</p>
-  </div>
-
-<p>In Fig. 45 the Water Boatman (<i>Notonec´ta glauca</i>) is represented
-as seen from above&mdash;a position in which we shall rarely discover it,
-if we keep it in a small aquarium. In Fig. 46 the same insect is shown
-swimming on its back, or in the position it assumes when taking in a
-supply of air. The end of the abdomen and the tips of the<span class="pagenum" id="Page_94">[94]</span> feet rest
-against the surface-film; and at the slightest alarm a vigorous stroke
-of the last pair of legs sends the insect to a place of safety. From
-the way in which these insects habitually swim, Mouffet came to the
-conclusion that it was probable men learned the art of swimming on
-their backs from them.</p>
-
-  <div class="figcenter" id="i_094" style="width: 300px">
-     <img
-    class="p2"
-    src="images/i_094.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 46.</span>&mdash;Water Boatman swimming.</p>
-  </div>
-
-<p>Active as the Water Boatman is, it often falls a victim to the Water
-Scorpion, if both are kept in the same aquarium. I learnt this fact by
-experience, for having put two Water Boatmen into a small tank in which
-was a Water Scorpion, I found both the former dead in the morning. It
-was evident that their destroyer had had a good meal.</p>
-
-<p>The only point to which attention need be called in examining the Water
-Boatman is its method of taking in a supply of air. In looking at a
-dead specimen we shall see a ridge or keel running down the middle of
-the under side of the abdomen, and fringed with hair on each side.
-A similar fringe runs along each side of the abdomen, thus forming
-two passages along which the air taken in at the end of the body is
-conveyed to the spiracles, the largest of which are on the thorax.</p>
-
-<p>Corixa (Fig. 47) swims with its back uppermost, and when kept in the
-aquarium may generally be seen foraging for small creatures&mdash;larvae or
-worms&mdash;among the sediment at the bottom. Bateman, who<span class="pagenum" id="Page_95">[95]</span> kept a number
-of these insects, says that he fed his specimens on garden worms and
-pieces of raw meat. Mine have always foraged for themselves, and done
-very well without feeding. They may often be seen to rub the short
-fore-legs alternately across the front of the head, probably for the
-purpose of producing a call-note. I have often watched them at this
-practice, but have never been able to detect any sound. The defect is
-evidently in my sense of hearing, for the sounds rest on undoubted
-authority, and are coincident with the rubbing of the fore-legs across
-the head.</p>
-
-  <div class="figcenter" id="i_095" style="width: 300px">
-     <img
-    class="p2"
-    src="images/i_095.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 47.</span>&mdash;Corixa, with wings expanded.</p>
-  </div>
-
-<p>Where sound-producing organs exist it is more than probable the
-capacity for receiving sound-impressions also exists. Graber made some
-interesting experiments to test the sense of hearing in Corixa. His
-results are thus summarized by Sir John Lubbock<a id="FNanchor_28" href="#Footnote_28" class="fnanchor">[28]</a>: ‘He placed some
-Water Boatmen (Corixa) in a deep jar full of water, at the bottom
-of which was a layer of mud. He dropped a stone on the mud, but the
-insects, which were reposing quietly on some weeds, took no notice. He
-then put a piece of glass on the mud, and dropped the stone on to it,
-thus making a noise, though the disturbance of the water was the same.
-The Water Boatmen, however, at once took to flight.’</p>
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_96">[96]</span></p>
-
-<h2>CHAPTER IV<br />
-<span class="subhed">SPIDERS, MITES, AND MYRIAPODS</span></h2></div>
-
-<div>
-<img class="drop-cap" src="images/i_096a.jpg" width="50" alt=""  />
-</div>
-
-<p class="drop-cap p-left">In this chapter we shall take examples from two Classes&mdash;the
-Arachnoi´dea and the Myriap´oda. To the first-named Class belong also
-the Scorpions, which, with the Book Scorpions, the Harvestmen, and some
-others, may be neglected here. This will leave us only the Spiders and
-Mites to deal with.</p>
-
-<p>Every one knows a Spider when he sees one, though not every one can
-give offhand a definition that shall include the whole Order. Let us
-endeavour to express their characters in simple terms, keeping in mind
-the definition of head, thorax, and abdomen in Chapter II. In Spiders
-the head and thorax are joined together in one unsegmented portion,
-called the cephalothorax, and this is connected with the abdomen, which
-is also unsegmented, by a more or less slender stalk or peduncle. So
-that while Insects have three regions, Spiders have but two. We may
-express the difference thus:</p>
-
-<table summary="dates" class="smaller">
-  <tr>
-    <td class="cht">Insects</td>
-    <td class="cht3">head, thorax</td>
-    <td class="cht3">abdomen.</td>
-  </tr>
-
-  <tr>
-    <td class="cht"></td>
-    <td class="cht3"><img src="images/i_096b.jpg" alt=""
-style="height:.5em; vertical-align: middle;" />
-</td>
-    <td class="cht3"></td>
-  </tr>
-
-  <tr>
-    <td class="cht">Spider</td>
-    <td class="cht3">cephalothorax</td>
-    <td class="cht3">abdomen.</td>
-  </tr>
-</table>
-
-<p><span class="pagenum" id="Page_97">[97]</span></p>
-
-<p>The cephalothorax bears six pairs of appendages (Fig. 48<span class="allsmcap">A</span>).
-Taking these in order, there are&mdash;</p>
-
-<div class="blockquot">
-
-<p>1. A pair of falces (<i>an</i>), representing the antennae of
-insects. These have a movable claw-like joint at the extremity,
-perforated so as to convey into a wound the secretion from the
-poison-glands.</p>
-
-<p>2. A pair of five-jointed pedipalps (<i>p</i>), sometimes called
-maxillary palpi, from the fact that the parts whence they spring
-correspond to the maxillae of insects (Fig. 21<span class="allsmcap">A</span>,
-<i>d</i>). In the female the last joint terminates in a claw; in
-the male this joint is specially modified for sexual purposes
-(Fig. 48<span class="allsmcap">B</span>).</p>
-
-<p>3. Four pairs of walking legs, of which only the coxae
-(<i>c</i>) are shown in the diagram. The two front legs are
-often used as organs of touch.</p>
-</div>
-
-<p>Breathing is carried on by chambered air-tubes or lung-sacs, and in all
-our British Spiders (with the single exception of the native Trap-door
-Spider, which, by the way, does not make a trap-door) there are also
-air-tubes resembling those of Insects. The lung-sacs open to the
-external air by stigmata (<i>st</i>) on the abdomen, while the ordinary
-air-tubes open near the spinnerets (<i>sp</i>), the organs employed in
-the production of the silky threads from which are formed webs, nests,
-egg-bags, and ropes. By means of these threads, spiders drop from their
-webs to the ground, construct flying bridges from one point to another,
-and even in some sort travel through the air.</p>
-
-<p>Spiders live upon the juices of their prey, which are drawn up into the
-stomach by means of a suctorial apparatus at the end of the gullet.<span class="pagenum" id="Page_98">[98]</span>
-The young, when they leave the egg, resemble their parents in all
-respects but size&mdash;that is, they undergo no metamorphosis.</p>
-
-<p>The eyes of spiders are simple, and six or eight in number. These vary
-much in size and relative position, and furnish characters of great
-importance in classifying species. Those of the Hunting Spiders, which
-make no web, but pursue or spring upon their prey, are usually arranged
-in three rows; while those which make webs for the capture of prey have
-the eyes in a double row. In all cases they are on the front part of
-the upper surface of the cephalothorax.</p>
-
-  <div class="figcenter" id="i_098" style="width: 332px">
-     <img
-    class="p2"
-    src="images/i_098.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 48.</span>&mdash;<i>A.</i> Scheme of under surface of Wolf
-Spider (female). <i>B.</i> Pedipalp of male (enlarged). For
-other references, see text.</p>
-  </div>
-
-<p>The Common Garden Spider (<i>Epei´ra diade´ma</i>) is a very good
-subject, and there can be no difficulty in procuring any number of
-specimens. The smallest garden will be sure to yield a plentiful
-supply; and even if we have no garden, a very superficial search
-among the hedgerows will give us as many as we can possibly want.
-Every one knows this spider, and the beautifully regular web which
-it makes. First of all, what one may call the outline of the web
-is spun&mdash;strong threads stretching from<span class="pagenum" id="Page_99">[99]</span> point to point, to which
-are attached lines radiating from a common centre. This may be
-represented diagrammatically by drawing a circle and producing radii
-from the centre to the circumference in all directions, or by making a
-rectangular figure and drawing lines to the boundaries from the point
-where the diagonals intersect. It must not, however, be supposed that
-the outline of the web is of a regular form. In this respect the spider
-adapts itself to circumstances, and spins a greater or less number of
-supporting threads, as may be necessary.</p>
-
-  <div class="figcenter" id="i_099" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_099.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 49.</span>&mdash;Garden Spider and Web.</p>
-  </div>
-
-<p>Then the spiral is made (Fig. 49) from the centre to the circumference.
-The first few turns are of the same character as the radial lines; but
-all the rest of the short lines forming the spiral, and connecting
-the radial lines, are coated with a viscid secretion, which is the
-essential part of the snare; for the victims are really limed like
-birds on a twig, not entangled in the threads. It is well to test the
-character of the different parts of the spiral, not only by touch,
-which is convincing enough, but with pocket lens. Our low powers will
-not give such results as are shown in Fig. 50, but we shall have no
-difficulty in distinguishing the sticky parts from those not coated
-with the secretion.</p>
-
-  <div class="figcenter" id="i_100" style="width: 350px">
-     <img
-    class="p2"
-    src="images/i_100.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 50.</span>&mdash;<i>A</i> Adhesive Threads of Spiral.
-<i>B.</i> Non-adhesive Radial Threads.</p>
-  </div>
-
-<p>It may be doubted whether all the Spiders of this genus make the
-spiral in the same way, for<span class="pagenum" id="Page_100">[100]</span> observers differ in their description of
-what they have seen. Some say that a non-adhesive spiral from centre
-to circumference is first made, and that the spider then moves ‘in a
-closer spiral from the circumference inwards, biting away the former
-spiral, replacing it by another, which is viscid and adhesive<a id="FNanchor_29" href="#Footnote_29" class="fnanchor">[29]</a>.’ Dr.
-Butler, on the other hand, who ‘watched spiders for months together,
-petting, feeding, and trying experiments with them every morning,’
-after describing the making of the first and non-adhesive part of the
-spiral, says, ‘This line is not carried to the boundary, but at some
-distance from the centre a second is commenced, formed of extremely
-viscid silk, upon which the gummy secretion is distinctly visible,
-with the aid of a lens, in the form of closely approximated globules
-of amber-coloured glue. It is said that when the viscid lines are
-completed the spider cuts away the unadhesive lines, but this I have
-never observed<a id="FNanchor_30" href="#Footnote_30" class="fnanchor">[30]</a>.’ My own observations lead me to believe that Dr.
-Butler is correct in his description. Though I have often watched,
-I have never<span class="pagenum" id="Page_101">[101]</span> seen a spider ‘biting’ away any part of its web, nor
-would the falces appear to be adapted for such an operation. They are
-piercing, not cutting, weapons.</p>
-
-<p>The spider may be watched at leisure, if put into a bottle of moderate
-size, the top of which should be covered with muslin or calico to
-prevent escape. Here it is fairly easy to bring the pocket lens into
-play, and to distinguish the different parts of the animal. The eyes,
-and their arrangement, should be particularly noticed.</p>
-
-  <div class="figcenter" id="i_101" style="width: 242px">
-     <img
-    class="p2"
-    src="images/i_101.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 51.</span>&mdash;Anchorage of Web.</p>
-  </div>
-
-<p>Blackwall, in support of the position that in making their webs
-spiders are guided by touch rather than sight, says, ‘Various species,
-when confined in spacious glass jars placed in situations absolutely
-impervious to light, construct nets which do not exhibit the slightest
-irregularity of plan or defect of structure<a id="FNanchor_31" href="#Footnote_31" class="fnanchor">[31]</a>.’ My specimens have
-always been kept in the light, and in small bottles rather than
-spacious jars, but I have never seen spiders attempt to make a
-geometrical web under such conditions.</p>
-
-<p>A bottle which for some months served as a prison-house for a Garden
-Spider now stands on my writing-table. Its sides are marked by hundreds
-of ‘anchorages’&mdash;but the threads cross and recross, forming in some
-parts a kind of sheet, and in others a tangled mass. Some of these<span class="pagenum" id="Page_102">[102]</span>
-threads must have been covered with viscid secretion, for flies were
-limed, and so fell a prey to the spider. Their dried skins are dotted
-about among the threads, and the spider itself perished long ago from
-cold. But I keep the bottle as a curiosity, to show that these spiders
-do not always make geometrical webs.</p>
-
-<p>When one has a Garden Spider in a bottle, it may be observed to
-practise a curious and very effective method of disabling its prey.
-If a bluebottle or any other large fly be dropped and entangled among
-the threads, the spider will envelop it in a sheet of web. This is
-how Blackwall describes the operation: ‘Causing the victim to rotate
-by the action of the third pair of legs and the palps, the first pair
-of legs also being frequently employed in a similar manner, they
-extend the spinners laterally, and applying to them alternately the
-<i>sustentaculum</i> of each posterior leg, they seize and draw out
-numerous fine lines in the form of a fillet, which they attach to their
-revolving prey, and thus involve it in a dense covering of silk from
-one extremity to the other. By means of this stratagem they are capable
-of overcoming formidable and powerful insects, such as wasps, bees, and
-even large beetles<a id="FNanchor_32" href="#Footnote_32" class="fnanchor">[32]</a>.’</p>
-
-<p>The operation does not occupy much time; in a very few minutes the fly
-is swathed in a silky covering as completely as an Egyptian mummy in
-its linen folds. Of course resistance, much less attack, is out of the
-question, and when it is thus rendered powerless for harm the spider
-proceeds with its meal.</p>
-
-<p>The <i>sustentac´ulum</i>&mdash;or support&mdash;is a strong<span class="pagenum" id="Page_103">[103]</span> movable spine near
-the end of the tarsus, on the under side of each of the last pair of
-legs. These spines act in opposition to the claws, and thus these
-animals are enabled to hold with a firm grasp such lines as they have
-occasion to draw from their spinners with the feet of the hind legs,
-and such also as they design to attach themselves to.</p>
-
-<p>With regard to this method of swathing prey, Hudson<a id="FNanchor_33" href="#Footnote_33" class="fnanchor">[33]</a> says of
-an Argentine spider, ‘that its intelligence has supplemented this
-instinctive procedure with a very curious and unique habit. The
-Pholcus, in spite of its size, is a weak creature, possessing
-little venom to dispatch its prey with, so that it makes a long and
-laborious task of killing a fly. A fly, when caught in a web, is a
-noisy creature, and it thus happens that when the Daddy longlegs&mdash;as
-Anglo-Argentines have dubbed this species&mdash;succeeds in snaring a
-captive, the shrill outrageous cries of the victim are heard for a
-long time&mdash;often for ten or twelve minutes. This noise greatly excites
-other spiders in the vicinity, and presently they are seen quitting
-their webs and hurrying to the scene of conflict. Sometimes the captor
-is driven off, and then the strongest or most daring spider carries
-away the fly. But where a large colony are allowed to continue for a
-long time in undisturbed possession of a ceiling, when one has caught
-a fly he proceeds rapidly to throw a covering of web over it, then,
-cutting it away, drops it down and lets it hang suspended by a line at
-a distance of two or three feet from the ceiling. The other spiders
-arrive on the scene, and after a short investigation retreat to their
-own<span class="pagenum" id="Page_104">[104]</span> webs, and when the coast is clear our spider proceeds to draw up
-the captive fly, which is by this time exhausted with its struggles.’</p>
-
-<p>In this connexion Hudson notes that spiders are attracted by the sound
-of the vibration of a string or wire, thinking it made by an insect
-that has been caught; and he says that the stories of tame spiders
-are founded on a misunderstanding of the motive that brings the
-animal down. We may well doubt if spiders are attracted by music, but
-that some spiders possess a sense of hearing, or something analogous
-thereto, seems to be proved by the existence of stridulating organs in
-certain members of the group.</p>
-
-  <div class="figcenter" id="i_104a" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_104a.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 52.</span>&mdash;Foot of Garden Spider.</p>
-  </div>
-
-  <div class="figcenter" id="i_104b" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_104b.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 53.</span>&mdash;Spinnerets of Garden Spider.</p>
-  </div>
-
-<p>Two other points remain to be noted. The feet should be examined,
-for their structure throws some light on the way in which the Garden
-Spider runs so securely to and fro on the radial lines. One of the
-legs of a dead specimen should be detached, and its armature of spines
-and hairs noted. The foot is armed with three stout claws, which
-are pectinated&mdash;that is, toothed like a comb, and beneath them are
-smaller ones, sometimes described<span class="pagenum" id="Page_105">[105]</span> as toothed hairs. It will be easy
-to understand what a secure foothold these claws give the animal as it
-runs backwards and forwards over the radial lines; for if the web be
-shaken by the wind or designedly its owner can take a firm hold with
-each foot, and thus have eight separate points of attachment. An inch
-hand lens is quite sufficient to give a general idea of the hairy and
-spinous clothing of the legs and the position of the claws; but to see
-the teeth a higher power&mdash;a half-inch&mdash;will be necessary.</p>
-
-<p>It is a good plan to choose a freshly killed specimen for the
-examination of its spinnerets. If the spider is laid on its back in a
-glass dish, gentle pressure on the abdomen away from the cephalothorax
-will cause the material secreted by the spinning-glands to ooze out.
-This, however, cannot be done if the specimen has been for some time
-in spirit. We shall be able to make out six tubes (four of them larger
-than the other two) grouped round the anal aperture; but, for the
-present, we must take for granted the fact that these are made up of
-a number of smaller tubes, so that the end of each spinneret is not
-unlike the rose of a watering-can. A good half-inch will give some
-indications of this rose-like appearance.</p>
-
-<p>The Jumping Spider (<i>Sal´ticus sce´nicus</i>) belongs to a family
-the members of which make no web or snare for the capture of prey, but
-trust for their food-supply to their skill in stalking flies and other
-insects, which they capture by a sudden spring. It is from this habit
-that the type-genus and the family have received their scientific and
-popular names.</p>
-
-<p>The common British species is extremely abundant, and wherever flies
-are plentiful these<span class="pagenum" id="Page_106">[106]</span> spiders will not be very far off. This is the case
-not only in the country, but also in London and other large towns. It
-is a noticeable spider from its coloration&mdash;black marked with white.
-The eyes are eight in number; though the artist in our illustration
-has only represented four. The centre two of the front are the largest
-of all, and have been compared not inaptly to bull’s eyes. Two others
-are placed on each side of the cephalothorax, so that the eyes form,
-roughly, three sides of a square, and the central eyes in the lateral
-lines are the smallest. We may represent them thus <img src="images/i_106c.jpg" alt=""
-style="height:1.5em; vertical-align: middle;" />, while the
-eyes of the Garden Spider are disposed in this fashion <img src="images/i_106d.jpg" alt=""
-style="height:1.5em; vertical-align: middle;" />.</p>
-
-  <div class="figcenter" id="i_106a" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_106a.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 54.</span>&mdash;Jumping Spider. (Line shows natural
-size.)</p>
-  </div>
-
-  <div class="figcenter" id="i_106b" style="width: 194px">
-     <img
-    class="p2"
-    src="images/i_106b.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 55.</span>&mdash;Falces of Male Jumping Spider.</p>
-  </div>
-
-<p>It requires some little practice to detect the eyes of spiders and to
-remember their position in the different genera, but by examining every
-spider met with, and consulting some handbook to the group, one will
-soon be able to determine the commoner British species.</p>
-
-<p>With a couple of needles we may remove the<span class="pagenum" id="Page_107">[107]</span> falces (Fig. 55) for
-examination; and there is no difficulty in mounting them, as shown in
-the cut, on a piece of card, so that they may be compared with the same
-weapons in other species. For example, the falces of the Garden Spider
-differ from those of the Jumping Spider in that they are short and
-stout, and the teeth on the basal joint are more in number.</p>
-
-<p>The following account of the habit of this spider in capturing prey is
-from Kirby and Spence’s <i>Introduction to Entomology</i> (ed. 1870, p.
-453):&mdash;‘When these insects spy a small gnat or fly upon a wall, they
-creep very gently towards it with short steps, till they come within a
-convenient distance, when they spring upon it suddenly like a tiger.
-Bartram observed one of these spiders that jumped two feet upon a
-humble-bee. The most amusing account, however, of the motions of these
-animals is given by the celebrated Evelyn in his <i>Travels</i>. When
-at Rome, he often observed a spider of this kind hunting the flies
-which alighted upon a rail on which was its station. It kept crawling
-under the rail till it arrived at the part opposite to the fly, when
-stealing up it would attempt to leap upon it. If it discovered that
-it was not perfectly opposite, it would immediately slide down again
-unobserved, and at the next attempt would come directly upon the
-fly’s back. Did the fly happen not to be within a leap, it would move
-towards it so softly, that its motion seemed not more perceptible
-than that of the shadow of the gnomon of a dial. If the intended prey
-moved, the spider would keep pace with it as exactly as if they were
-actuated by one spirit, moving backwards, forwards, or on each side
-without turning. When the fly took wing, and pitched<span class="pagenum" id="Page_108">[108]</span> itself behind the
-huntress, she turned round with the swiftness of thought, and always
-kept her head towards it, though to all appearance as immovable as one
-of the nails driven into the wood on which was her station: till at
-last, being arrived within due distance, swift as lightning she made
-the fatal leap and secured her prey.’</p>
-
-<p>This spider employs a clever precaution against falling, when about to
-spring upon its prey. It applies the end of the abdomen to the surface
-on which it stands, and opening its spinnerets, makes an ‘anchorage’
-(Fig. 56). Then, by the act of springing, it draws from the spinnerets
-a line attached to the spot from which it started. This line is strong
-enough to support the spider in case it misses its prey.</p>
-
-  <div class="figcenter" id="i_108" style="width: 300px">
-     <img
-    class="p2"
-    src="images/i_108.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 56.</span>&mdash;<i>A.</i> Foot or Jumping Spider. <i>B.</i>
-Scopula. (Much enlarged.)</p>
-  </div>
-
-<p>The foot of the Jumping Spider is extremely interesting, and shows
-a very ingenious arrangement, by means of which the animal can run
-with difficulty on smooth polished upright surfaces, or retain its
-footing when it alights on such surfaces after a spring. We can see
-this arrangement in Fig. 56. Just behind the claws is a bundle of
-coarse hairs, technically called a <i>scop´ula</i>, or little brush.
-From these hairs adhesive matter flows, and in this fashion the spider
-literally sticks on. With this brush of hairs may be compared the
-tarsal cushions of many flies, and the adhesive hairs of Dytiscus
-and other beetles (see Chap. II)&mdash;though these last have a different
-function.</p>
-
-<p>Diving Spiders (<i>Argyrone´ta aquat´ica</i>) are especially suitable
-for our purpose. They are very<span class="pagenum" id="Page_109">[109]</span> common in most ponds, and in some
-places are so abundant as to be almost a nuisance to the collector who
-is in search of other things. Three of them are represented in Fig. 57.
-One is swimming; another is just entering the bell-shaped web under
-water; and the third is just climbing out of the water on to the broad
-floating leaves of the water crowfoot.</p>
-
-  <div class="figcenter" id="i_109" style="width: 361px">
-     <img
-    class="p2"
-    src="images/i_109.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 57.</span>&mdash;Diving Spiders.</p>
-  </div>
-
-<p>De Geer’s account of these spiders is extremely<span class="pagenum" id="Page_110">[110]</span> interesting<a id="FNanchor_34" href="#Footnote_34" class="fnanchor">[34]</a>, and
-we may verify it for ourselves, for these creatures may be kept without
-any trouble. They certainly agree, when a number are kept in captivity,
-much better than do other spiders. De Geer kept several in the same
-aquarium, and says that when they met they felt each other with their
-palps, and opened their falces, but he never saw them do any harm to
-each other. I have kept them under similar conditions with the same
-result.</p>
-
-<p>He tells us that these spiders spin under water a cell of strong,
-close, white silk, the shape of which he compares to a skull-cap, the
-half of a pigeon’s egg, or a diving-bell. In September, 1736, he first
-became acquainted with these creatures, and kept one in an aquarium for
-four months. It made its cell against the side of the aquarium, and the
-top of it rose above the surface of the water. (This was due to its
-being inflated. The web was not spun above the surface.) The walls of
-the cell were very thin, but it was filled with air, and the spider was
-resting inside, head uppermost, with its legs pressed against the body.</p>
-
-<p>About three months later he found that the mouth of the cell was
-closed, and the spider was comfortably settled in its winter quarters.
-When pressure was applied the cell burst and the air escaped, mounting
-up to the top in bubbles. The spider made its way out, and took an
-Asellus that was offered, and made a meal of it.</p>
-
-<p>De Geer then came to the conclusion that these cells under water were
-constructed for the purpose of affording the spider a retreat when the
-water was frozen over, so that they could not come to<span class="pagenum" id="Page_111">[111]</span> the surface
-for a supply of air. He found, however, by observation, that they
-were also made in summer by both sexes. In a cell of this kind the
-female deposits her eggs&mdash;from eighty to a hundred in number, enclosed
-in a cocoon of white silk&mdash;and keeps guard over them, with her head
-defending the entrance to the cell.</p>
-
-<p>He succeeded in finding out the method by which the Diving Spider fills
-its cell with air. He noticed that when the creature was moving about
-in the water, its body was covered with a layer of air, and that this
-air was renewed from time to time when the animal came to the surface
-and raised its abdomen above the water. Loaded, so to speak, with air
-in this fashion, the spider descended, and entered the cell backwards,
-leaving an air-bubble. Having repeated this several times, at last she
-removed all the water from the cell, introducing in its place an equal
-quantity of air.</p>
-
-<p>It is very easy to watch the Diving Spider making its dwelling under
-water, and filling it with air. First of all the web is woven in a
-bell or thimble shape between the sprays of water-weed, or against the
-bottom or side of the aquarium. It is curious to notice how practices
-that must be necessary when the creature is at liberty are continued
-in captivity where they are useless. A web constructed in running
-water, or even in a pond or ditch, is liable to be swept away or to be
-emptied of air by a very slight current, so its owner has recourse to
-a system of guys and supporting threads, which are not required when
-the spider is safely housed in a small aquarium. Nevertheless, the guys
-are made. In an eight-ounce bottle I have now a male Diving Spider,
-which has lived there for about seven months. Its<span class="pagenum" id="Page_112">[112]</span> cell is made between
-the whorls of a spray of milfoil, and guy threads have been carried to
-no less than five whorls&mdash;two above and three below the opening. Now
-that it is filled with air, the cell gleams in the water like a great
-bubble of quicksilver. The air may be expelled by shaking or tilting
-the bottle, and if the web be not damaged the spider will generally
-refill it with air, though sometimes it prefers to make a new dwelling.
-Fig. 58 shows the cell of a Diving Spider; the white lines represent
-supporting threads attached to the water plants.</p>
-
-<p>In examining dead specimens we shall find that, contrary to what is
-usual, the male exceeds the female in size. I have a slide of a male,
-with the legs spread out before and behind, and the measurement from
-the claws of the first pair of legs to those of the fourth pair is 1¾
-inches. The body is ¾ inch long. The whole surface is more thickly
-clothed with hair than is the case with other spiders, and the reason
-for this is obvious. This hairy body-covering serves to carry down into
-the water a layer of air, and the fringe of hair on the legs makes them
-efficient swimming organs.</p>
-
-  <div class="figcenter" id="i_112" style="width: 338px">
-     <img
-    class="p2"
-    src="images/i_112.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 58.</span>&mdash;Cell of Diving Spider.</p>
-  </div>
-
-<p>The Order of Mites will yield us subjects for our pocket lens. Mites
-are related to Spiders, but form a distinct Order. Like the Spiders,
-some<span class="pagenum" id="Page_113">[113]</span> are aquatic, though the most of them live on land. Many are
-parasitic, during the whole or part of their lives subsisting on
-the juices of their hosts: the food of others consists of organic
-<i>débris</i>, and these seem to be of benefit to man, since they act
-as scavengers. If we turn to page 96 we shall there find noted the
-points of difference in the arrangement of the main divisions of the
-body in Insects and in Spiders. In Mites the distinction between the
-cephalothorax and abdomen is lost, and the body is more or less oval or
-globular. In the perfect forms there are eight legs; but some, in their
-earlier stages, have only six. The mouth may be adapted for biting,
-though it is usually suctorial. In the Cheese Mites and some others
-breathing seems to be carried on through the skin, for there are no
-air-tubes; but in most Mites air-tubes, with two stigmata, are present.</p>
-
-<p>If we take a dip with the collecting-net in almost any pond we shall
-be pretty sure to capture some specimens of Water Mites of the genus
-Hydrach´na, easily recognizable by their bright coloration, their eight
-swimming legs thickly fringed with hair, and their unceasing activity.
-They may be kept in a bottle, or other small vessel, with some
-water-weed, and will forage for themselves. In Fig. 59 we shall see
-the points we have to look for in examining a Water Mite with a pocket
-lens. There should be no difficulty in making out in the specimen all
-the details shown in the cut.</p>
-
-<p>It may be that they will breed: if so we should avail ourselves of
-the opportunity of watching their development. Their life-history is
-somewhat curious, and is specially interesting from the fact that
-while Swammerdam had some faint perception of the true meaning of what
-he saw,<span class="pagenum" id="Page_114">[114]</span> De Geer, writing a hundred years later, drew entirely wrong
-conclusions from similar observations. It was left for Dugès to clear
-up the matter in the <i>Annales des Sciences Naturelles</i>, 1834.
-Before summarizing the account of the French naturalist it may be well
-to quote what Swammerdam and De Geer have said on the subject:&mdash;</p>
-
-<p>‘There is nothing more remarkable in this insect [the Water Scorpion]
-than that it constantly appears covered with a prodigious number of
-nits of different sorts and sizes, though perhaps we may with more
-reason consider them as so many little creatures, which live and grow
-by sucking the Scorpion’s blood. These are somewhat of an oblong
-figure, approaching to round, and have a shining, and as it were
-bloated, surface, without any of the rings observable in most insects.
-The neck is oblong and shaped like a pear, with the small end sticking
-in the Scorpion’s body. The colour of this insect is a mean between
-that of vermilion and purple; and when it is pretty well grown there
-appears within it an elegant transparent spot or particle (Fig. 59).</p>
-
-  <div class="figcenter" id="i_114" style="width: 297px">
-     <img
-    class="p2"
-    src="images/i_114.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 59.</span>&mdash;Red Water Mite (nat. size, and under
-surface magnified).</p>
-  </div>
-
-<p>‘This spot or particle induced me to consider with more attention
-this minute and hitherto unregarded insect, and even to undertake the
-dissection of it. But who would imagine that on this<span class="pagenum" id="Page_115">[115]</span> examination it
-should prove a perfect and surprising insect? This is, however, a
-certain fact; and thus in that infinite variety of works, by means of
-which God is pleased to make Himself known to us, we ever meet with new
-matter of admiration and astonishment.</p>
-
-<p>‘This little creature being extracted from the shell that covered it,
-looks like a young spider before it has left its egg. On the fore part
-is the head (Fig. 43<span class="allsmcap">D</span>, <i>a</i>) and on its head are the eyes,
-<i>b</i>: under the eyes are placed its little legs elegantly coiled
-and folded, <i>c</i> <i>c</i>; but they appear much more distinctly
-on turning the insect on its back, <i>d</i> <i>d</i>; and in this
-situation also it best appears with what art these legs are laid
-up in the shell, and all are covered with hair. The colour of this
-little creature is, as I have already observed, a mean between that of
-vermilion and purple; and this colour shows itself through the coat
-or shell, which is transparent. I cannot determine to what species of
-insects this is to be referred; nor can I say to what size it grows, or
-by what kind of creature it is thus deposited on the Water Scorpion in
-the form of an egg, there to receive life and growth. Nevertheless, I
-cannot but look on the discovery I have made as very interesting, since
-it proves that there are in the nature of things eggs which acquire
-a sensible growth by an entraneous nourishment, unless perhaps some
-naturalist should choose to consider this as a complete insect, rather
-than as an egg; nor shall I strenuously oppose his opinion, seeing
-that, in all cases, the egg is in reality no other than the insect
-itself, which remains in that state till it has acquired sufficient
-strength to break its prison, and live without such a covering<a id="FNanchor_35" href="#Footnote_35" class="fnanchor">[35]</a>.’</p>
-
-<p><span class="pagenum" id="Page_116">[116]</span></p>
-
-<p>Having quoted Swammerdam, let us see what De Geer has to say on the
-subject:&mdash;</p>
-
-<p>‘On the body and legs of many aquatic insects, such as Dytiscus and
-Water Scorpions, may be frequently seen little oval, seed-like bodies,
-of a bright red colour, firmly attached, and, as it were, implanted
-in the skin, by a little stalk. I have had Water Scorpions with the
-upper surface so covered with these red bodies that there was scarcely
-a vacant space on the skin. They are most frequently to be seen in
-the spring; but the insects on which there was such a great number
-did not live long with me. Having crushed some of these seed-like
-bodies, I found them filled with red liquid matter. I am convinced, by
-experiment, that they are the eggs of Water Mites, since there came out
-of them little red Mites with round bodies and long legs, which swam
-about with great swiftness.</p>
-
-<p>‘These red Water Mites, then, attach their eggs to the bodies and legs
-of larger aquatic insects, and there they remain till the young are
-hatched. And since we find eggs of many different sizes, we may be
-sure that they grow and increase in size, doubtless owing to a certain
-nutritive juice which passes from the body of the insect into the egg.
-Hence it is, as I have seen myself, that Water Scorpions loaded with
-these eggs become weak and feeble, because they are obliged to furnish
-their hangers-on with nourishment from their own bodies. Moreover,
-these eggs appear to cause the Water Scorpions some irritation or
-uneasiness, since I have often seen them rub with their feet those
-parts of the body where the eggs were; and perhaps they did this with
-the view of rubbing them off, but they were too securely fastened<a id="FNanchor_36" href="#Footnote_36" class="fnanchor">[36]</a>.’</p>
-
-<p><span class="pagenum" id="Page_117">[117]</span></p>
-
-<p>Dugès watched the development of the common Red Water Mite (Fig. 59),
-and tells us that towards the end of May the females deposit their eggs
-in the leaves of pondweed, which they puncture with their beaks. The
-larva (Fig. 60), red in colour, with six legs, is free-swimming, and
-has a large beak, which looks like a great head, and terminates in a
-narrow mouth. It is not known how long this larval stage continues;
-but in the next stage (Fig. 61) the Mite becomes parasitic on aquatic
-beetles and bugs, fastening its beak into the body of its host,
-from which it derives its nourishment. The legs and palps are often
-retracted or absorbed, so that it is not difficult to understand
-how it was Swammerdam and De Geer took these parasitic nymphs to
-be the eggs of the Mite. During their parasitic condition they
-increase considerably in size, at last emerging as adult eight-legged
-free-swimming Mites. It was just before the emergence of the Mite
-that Swammerdam examined the parasitic nymph, for he figures the
-‘insect,’ which he extracted from the egg, as having eight legs (Fig.
-43<span class="allsmcap">D</span>).</p>
-
-  <div class="figcenter" id="i_117a" style="width: 270px">
-     <img
-    class="p2"
-    src="images/i_117a.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 60.</span>&mdash;Larva of Water Mite.</p>
-  </div>
-
-  <div class="figcenter" id="i_117b" style="width: 150px">
-     <img
-    class="p2"
-    src="images/i_117b.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 61.</span>&mdash;Nymph of Water Mite.</p>
-  </div>
-
-<p>I once found a Water Mite in the body of a<span class="pagenum" id="Page_118">[118]</span> Dytiscus<a id="FNanchor_37" href="#Footnote_37" class="fnanchor">[37]</a>. I was
-breaking up the beetle, and had removed the elytra and the wings. I
-only wanted the external skeleton; so a slit was made between the
-plates of the dorsal and ventral surface, and the intestines removed.
-The Mite was embedded in the fat-body. I could find no mention in the
-literature of Beetles or Mites of any similar occurrence; and should
-scarcely have mentioned it here, had I not been unexpectedly confirmed
-by my friend Mr. G. E. Mainland, F.R.M.S., who once had a similar
-experience, and who kindly allows me to quote from a letter he sent me
-on the subject:&mdash;</p>
-
-<p>‘I am sorry to say I can find no documentary evidence as to the
-Arachnid I found embedded in the tissues of Dytiscus, but a good deal
-has come back to my recollection. On removing the right elytron and
-slitting up the dorsal surface, I found it in the tissue close up to
-the thorax. I cannot recollect what ultimately became of it, after I
-had shown it to friends at the Hackney Microscopical Society.... I know
-that I carefully measured the Hydrachna (which was abnormally large)
-and its relative size to that of its host, and made a comparison in a
-lecture (to the Senior Band of Hope at St. Michael’s, Hackney) of a man
-with a creature as large as a guinea-pig under his shoulder-blade.’</p>
-
-<p>The occurrence of the Mite <i>inside</i> the Beetle was, of course,
-quite exceptional. It probably found its way in through one of the
-abdominal spiracles.</p>
-
-<p><span class="pagenum" id="Page_119">[119]</span></p>
-
-<p>The Beetle Mite (<i>Gam´asus coleoptrato´rum</i>) (Fig. 62) is
-extremely common, and is parasitic on the Dung Beetle and on the Humble
-Bee, so that in order to examine the parasite we must capture the host.
-There can be no difficulty about this, for Dung Beetles and Humble Bees
-are plentiful enough. This Beetle Mite, apparently, does not infest
-other species of beetles. I have kept the Devil’s Coach Horse in a
-bottle with the common Dung Beetle for some months, and though the
-latter swarmed with these parasites, they never left their host for
-the other beetle. Even when removed by means of a small brush from one
-beetle to the other, they left the Devil’s Coach Horse of their own
-accord, and soon made their way back to the Dung Beetle.</p>
-
-  <div class="figcenter" id="i_119" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_119.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 62.</span>&mdash;Beetle Mite.</p>
-  </div>
-
-<p>These parasites, with their host, came into my possession in a strange
-way. A friend, who knew my hobbies, told me that he had managed to
-procure for me some young beetles just born. I ventured to suggest that
-beetles were not born as beetles, but in quite a different shape. My
-suggestion was received unsympathetically, and I was told that I should
-alter my opinion when the creatures were sent me. But I did not. The
-box contained a Dung Beetle, over which were swarming scores of these
-little Mites, and I had some difficulty in convincing the gentleman
-who<span class="pagenum" id="Page_120">[120]</span> sent them to me that these Mites were not the young of the beetle.</p>
-
-<p>We should compare this Beetle Mite with the Water Mite, and notice the
-difference in the mouth parts and the legs, which have a large pad
-between the claws.</p>
-
-<p>We may find another Beetle Mite, closely allied to this species, on the
-Devil’s Coach Horse, and some of its near relations. This Mite was also
-known to De Geer<a id="FNanchor_38" href="#Footnote_38" class="fnanchor">[38]</a>, whose remarks upon it are worth quoting, in a
-condensed form.</p>
-
-<p>He found a beetle covered with these Mites, and on examining them with
-a hand lens saw that they were attached to their host by a long thread
-or stalk, which came from the posterior end of the body. Several Mites,
-he tells us, were joined together by one thread which fastened them all
-to the beetle; and he came to the conclusion that the parasites were
-nourished at the expense of the beetle, the thread serving to convey
-the juices of its body to them.</p>
-
-<p>‘It is very singular,’ he says, ‘to see living insects planted on the
-body of larger insects, from which they draw their subsistence by means
-of a thread or stalk.’ And then he goes on to compare these ‘vegetative
-Mites,’ as he calls them, with the ‘eggs’ of the Water Mites, which
-he found on Dytiscus and the Water Scorpion. The thread exists, and
-the Mites are attached by it to their host, but they do not draw
-nourishment through it from the beetle, for it is composed of their
-excrements.</p>
-
-<p>The Myriapods are worm-shaped creatures, breathing by means of
-air-tubes, and furnished with a number of limbs closely resembling
-each<span class="pagenum" id="Page_121">[121]</span> other. There are two groups: the Centipedes and the Millepedes.
-The former have the body flattened, with one pair of appendages to each
-segment, the first pair being modified into piercing poison-organs, and
-they feed on living prey. The body of the Millepedes is round, with two
-pairs of appendages to each segment; they have no poison-organs, and
-their food consists chiefly, if not entirely, of vegetable matter.</p>
-
-<p>There seems to be some doubt, however, as to whether <i>Ju´lus</i>, one
-of the commonest Millepedes, does not occasionally indulge in animal
-food. In <i>Nature Notes</i> (Jan. 1896) there was a review of the
-<i>Cambridge Natural History</i> (vol. v). The reviewer, in a brief
-summary of Mr. Sinclair’s part of the book (the Myriapods), said,
-after describing the Centipedes: ‘The millepedes, on the contrary, are
-sluggish vegetarians, with hard, cylindrical bodies, &amp;c.’ On this a
-correspondent wrote in the March number: ‘Some time ago my attention
-was attracted to a large earthworm, writhing and twisting about on
-the garden path, as though in pain, or through having received some
-injury. On examining it more closely to ascertain the cause of its
-unusual movements, I found that a millepede had fastened itself to the
-side of the worm, and appeared to be boring or eating its way into
-the body, whilst the most violent efforts on the part of the worm
-were ineffectual in shaking off its antagonist. If the millepede is
-a vegetarian, what could be its object in attacking so harmless and
-defenceless a creature as the earthworm? The above, which I take to
-be a millepede, is the black or dark-coloured creature “with hard,
-cylindrical body” ordinarily found coiled up in a spiral under stones
-or rubbish.’</p>
-
-<p><span class="pagenum" id="Page_122">[122]</span></p>
-
-<p>The editor, as a matter of course, referred the matter to the writer
-of the review. His reply was as follows: ‘If there is no mistake
-about the identity of the aggressor in the account cited above, the
-observation is one of considerable interest; for, so far as we are
-aware, it is the only case on record of a millepede being guilty
-of such conduct. But were it not for the positive statement that
-the species was the dark-coloured creature with a hard, cylindrical
-body, which is ordinarily found coiled up in a spiral under stones
-or rubbish&mdash;a description which exactly applies to the millepedes of
-the genus <i>Julus</i>&mdash;we should have concluded without hesitation
-that the struggle in question was merely one of those that habitually
-takes place between the centipedes of the genera <i>Litho´bius</i> or
-<i>Geoph´ilus</i> and the earthworms upon which they feed.’</p>
-
-<p>Both the Centipedes and Millepedes are shy, light-shunning animals,
-and if we turn over some stones in the garden or in a walk through the
-fields we shall probably find specimens enough to serve us in getting
-some idea of both groups.</p>
-
-<p>The Centipedes are sometimes called ‘Hundred-legs,’ but this implies
-the possession of many more legs than the creatures really have. In
-Norfolk and Suffolk the people call them ‘Forty-legs,’ and this is much
-nearer the mark.</p>
-
-<p><i>Litho´bius forfica´tus</i>, about an inch long and rufous brown in
-colour, is extremely abundant under stones and the bark of trees, and
-in cellars and outhouses. These animals run with great rapidity when
-disturbed, so that one needs to be on the alert to seize them when
-they are driven from the places in which they lurk. The body has nine
-principal and six subsidiary or smaller rings,<span class="pagenum" id="Page_123">[123]</span> and there are fifteen
-pairs of walking legs, besides the first pair, which are modified to
-serve as poison-organs. De Geer says that he never dared to pick up
-these Centipedes with ungloved hands, because he had seen a fly, which
-had been bitten by one, die on the spot, ‘which seems to be a sign that
-their bite is venomous.’ He examined their modified legs with a good
-microscope, but could not distinguish any opening. There is, however,
-an opening, as De Geer suspected, though he could not distinguish it;
-it lies near the point, and we may also trace the canal through the
-claw down to the poison-glands which lie, one on each side, at the base
-of the claws. The mouth parts resemble those of insects, and may be
-dissected out in the same way. When this Centipede walks, says De Geer,
-it does not use the last four pairs of legs, but drags them after it;
-but when it walks backwards, which it does as well as forwards, it then
-makes use of these four pairs of legs in the same way as the others. If
-we keep Lithobius alive we shall see that it can walk backwards, though
-it can scarcely be said to go as well one way as the other. From the
-same old writer some useful hints as to the method of keeping these
-animals may be gathered. Those that he kept in a vessel without any
-moisture soon died, and were quite dried up in twenty-four hours, which
-will teach us to keep them in a vessel with damp earth, shaded from
-light and heat.</p>
-
-<p>Dr. Sharp<a id="FNanchor_39" href="#Footnote_39" class="fnanchor">[39]</a> gives some interesting details about the breeding habits
-of Lithobius, and describes, for the first time, the uses of the two
-hooks on the under surface of the body of the female.</p>
-
-<p><span class="pagenum" id="Page_124">[124]</span></p>
-
-<p>He experimented with Centipedes and Millepedes. Keeping them in large
-shallow glass vessels, the bottom of which was covered with a layer
-of earth, he fed the specimens of Lithobius on insects and worms, and
-sometimes on raw chopped meat, but they did not thrive on this as they
-did on prey which they could kill for themselves.</p>
-
-  <div class="figcenter" id="i_124" style="width: 500px">
-     <img
-    class="p2"
-    src="images/i_124.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 63.</span>&mdash;<i>A.</i> <i>Lithobius
-forficatus.</i> <i>B.</i> Mouth parts seen from below (After Graber.)</p>
-  </div>
-
-<p>Lithobius, he tells us, lays but few eggs compared with the number
-deposited by Julus. Each egg, as it leaves the oviduct, is received
-by the hooks mentioned above, and by means of them it is rolled on
-the soil till a covering of earth adheres to the viscous material
-with which the egg is coated. The male considers the eggs special
-delicacies, and devours them whenever he has the opportunity. It is to
-prevent this that the female covers them with earth, so that the male
-may not recognize them.</p>
-
-<p>Geophilus is a much longer animal than Lithobius, for its body may
-consist of from 80 to 180 rings. The species have no eyes. Several of
-them are common, especially in the south of England, and possess, as
-do many genera of the same family, the property of phosphorescence,
-whence have<span class="pagenum" id="Page_125">[125]</span> arisen the stories of ‘luminous earthworms’ current from
-time to time. <i>Geophilus crassipes</i> is the form most frequently
-captured when displaying its light. It is from one inch to two inches
-long, of a reddish-orange colour, and somewhat worm-like in shape. Mr.
-Pocock, of the British Museum (Natural History), says: ‘The property
-of luminosity lies in an adhesive fluid secreted by glands which open
-upon the lower surface of the body, and the power of discharging or
-retaining the fluid appears to be entirely under the centipede’s
-control. The phenomenon is observable during the autumn months, from
-about the middle of September to the end of November, and although its
-significance is not clearly understood, it is generally believed to be
-connected with the pairing of the sexes<a id="FNanchor_40" href="#Footnote_40" class="fnanchor">[40]</a>.’</p>
-
-<p>During a visit to the seaside it is well to look out for specimens of
-a marine Centipede, which is, apparently, not very common. It is said
-to occur ‘under stones and sea-weeds on the shore at or near Plymouth’;
-and in 1895 I had the good fortune to meet with one at Bexhill.
-This Centipede does not live in the sea, but will survive prolonged
-immersion in salt water. It is far too valuable for us to pick to
-pieces, so that, if we should have the good fortune to meet with one,
-we should carefully examine it, making what notes are necessary, and
-then pickle the specimen and send it to the British Museum, Cromwell
-Road, S.W. The tube should be labelled with the place and date of
-capture, and it should be stated on the label whether the animal was
-taken above or below high-water mark.</p>
-
-<p>The Common Millepede&mdash;often miscalled the<span class="pagenum" id="Page_126">[126]</span> wireworm&mdash;is readily
-distinguished by the absence of poison-claws, and its cylindrical
-worm-like appearance. De Geer, who of course adopted the Linnaean
-definition of ‘Insects,’ says of the Millepedes of the genus Julus, to
-which our Common Millepede (<i>Ju´lus terres´tris</i>) belongs: ‘They
-form, as it were, the last link of the chain which unites the class of
-Insects to that of Worms, for the body is elongated and cylindrical;
-and though they have a great number of feet, these are so short, that
-when these animals walk, they seem rather to glide along after the
-fashion of legless worms<a id="FNanchor_41" href="#Footnote_41" class="fnanchor">[41]</a>.’</p>
-
-  <div class="figcenter" id="i_126" style="width: 400px">
-     <img
-    class="p2"
-    src="images/i_126.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 64.</span>&mdash;The Common Millepede.</p>
-  </div>
-
-<p>Dr. Sharp says that these animals do very well in confinement, and he
-found that sliced apples and grass formed the best food for them. He
-watched the process of nest-making and egg-laying, and these creatures
-are so abundant, and the necessary appliances so simple, that we may
-follow his<span class="pagenum" id="Page_127">[127]</span> example and see it for ourselves. His arrangements were the
-same as for Lithobius, and he saw the female make a hollow sphere of a
-bit of earth, stuck together by the secretion from the salivary glands,
-and smooth on the inside. A small hole was left on the top, and through
-this she passed in from 60 to 100 eggs, closing the aperture with earth
-moistened with the salivary secretion. The eggs were hatched in about
-twelve days. The young of all the Myriapods when they leave the egg
-have but three pairs of legs, but the number of limbs and segments is
-increased at each successive moult.</p>
-
-<p>Having watched our Millepedes in confinement, it will be well to take a
-preserved specimen and examine it carefully with the pocket lens, so as
-to compare it with the Centipede; then to compare both with the common
-earthworm, and to note the points of likeness and of difference. The
-dark spots on each segment in the illustration show the stigmata.</p>
-
-  <div class="figcenter" id="i_127" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_127.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 65.</span>&mdash;Segments of Millepede (magnified).</p>
-  </div>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_128">[128]</span></p>
-
-<h2>CHAPTER V<br />
-<span class="subhed">CRUSTACEANS.&mdash;PRAWN, SHRIMP, MYSIS, CRABS; AMPHIPODS; ISOPODS</span></h2></div>
-
-<div>
-<img class="drop-cap" src="images/i_128.jpg" width="50" alt=""  />
-</div>
-
-<p class="drop-cap p-left">The next group of Arthropod animals with which we have to deal is that
-of the Crusta´cea. Some or other of the members of this class are
-well known to everybody, if only in the shape of toothsome food&mdash;the
-Prawn, the Shrimp, the Lobster, the Crayfish, and the Crab. The great
-characteristic of this class of the Arthropod phylum is the so-called
-‘shell,’ which differs greatly from true shell in being composed of
-chitine, hardened with salts of lime. Most of the species live in the
-water and breathe by means of gills or through the skin. In dealing
-with these creatures, some long words must be employed, if our present
-work on them is to be a stepping-stone to something more advanced. The
-difficulty is more apparent than real, and if boldly faced will soon be
-overcome.</p>
-
-<p>Our first division, or sub-class, of the Crusta´cea is that of the
-Malacos´traca, or animals with soft shells&mdash;a name originally adopted,
-as Mr. Stebbing tells us<a id="FNanchor_42" href="#Footnote_42" class="fnanchor">[42]</a>, ‘to distinguish such creatures as crabs
-and crawfish and prawns from such others as oysters and clams; not
-because of the absolute,<span class="pagenum" id="Page_129">[129]</span> but because of the comparative softness
-of their shells.’ Under this sub-class are grouped two Orders&mdash;the
-Stalked-eyed and the Sessile-eyed Crustaceans, the technical names for
-which are the Podophthal´ma and the Edriophthal´ma.</p>
-
-<p>To the Stalked-eyed Crustaceans belong the Prawn, the Shrimp, Mysis,
-or the Opossum Shrimp, and the Crabs, to mention only those forms with
-which we are dealing here. The reason for scientific and popular names
-will be evident if living or spirit specimens are examined, for it will
-be seen that the eyes are elevated on stalks. Mr. Stebbing<a id="FNanchor_43" href="#Footnote_43" class="fnanchor">[43]</a> relates
-an amusing story of a very intelligent student, who, on being told that
-the eyes (of the shrimp) were stalked, candidly confessed to having
-always thought that this appearance was due to their having been forced
-out of the head by boiling.</p>
-
-<p>The general shape of a Prawn (<i>Palaemon serratus</i>) is fairly
-familiar to everybody. The body is divided into two principal
-regions&mdash;the carapace, or cephalothorax, as it used to be called
-(formed by the union of the head and thorax), and the pleon, or
-swimming part. The carapace has a projecting beak or rostrum, and is
-unsegmented; the pleon is divided into segments, and the whole may be
-represented thus:&mdash;</p>
-
-  <div class="figcenter" id="i_129">
-    <img
-    class="p0"
-    src="images/i_129.jpg"
-    alt="" />
-  </div>
-
-<p class="p-left">where the long stroke (<i>c</i>) stands for the carapace,
-the shorter ones (1–6) for the segments of the pleon, and the ) for the
-telson or tail. The carapace consists of fourteen united segments, and
-this<span class="pagenum" id="Page_130">[130]</span> will give twenty or twenty-one segments in all, according as we
-reckon the telson an appendage of the sixth segment of the abdomen,
-or as a distinct segment. The carapace bears the eyes, two pairs of
-antennae, six pairs of mouth appendages, and five pairs of walking legs
-or perei´opods, normally with seven joints&mdash;in all, fourteen pairs of
-appendages, that is, one pair for each of the fourteen segments of
-which the carapace is composed. The segments 1–5 of the ple´on bear
-swimming feet, or ple´opods, and the female uses these for retaining
-the eggs, which she bears about with her. In this fashion the ‘hen’
-lobster carries her ‘berries.’</p>
-
-<p>The Prawn is a capital inmate of the aquarium, and as it does well
-in confinement, specimens should be kept in order to get a general
-acquaintance with their form and external anatomy, and to watch their
-habits. The Common Prawn will answer the purpose, but still better is
-<i>Palaemone´tes varians</i>, an exceedingly common species. It has
-this advantage, that it ‘seems to be equally at home in salt water
-and fresh.’ The only condition necessary is a good supply of food,
-and this may be furnished by putting into the aquarium from time to
-time a quantity of water-fleas. If these Prawns are well fed they will
-shed their skins at frequent intervals, and this operation will give
-us material for examination, for the cast skin will serve our purpose
-almost as well as a spirit specimen.</p>
-
-<p>Some of these Prawns are now living in one of my aquaria. They were
-taken in a brackish dyke or cut near Newhaven, in Sussex, and in
-the mud which was brought back with them were a number of small
-bivalves of the genus <i>Sphaerium</i>. Most people know Mr. Kew’s
-exceedingly interesting<span class="pagenum" id="Page_131">[131]</span> book, <i>The Dispersal of Shells</i><a id="FNanchor_44" href="#Footnote_44" class="fnanchor">[44]</a>.
-In it he relates some extraordinary instances of the way in which
-species of shells are carried short distances, and may be carried
-from one district or country to another. These Prawns offered a good
-illustration of this, and practically confirmed some of the statements
-in his book, for on several occasions they were seen with the bivalve
-shells attached to their walking legs. The molluscs lay half buried
-in the mud and vegetable <i>débris</i> at the bottom of the tank,
-and as the Prawns walked about they sometimes trod between the open
-valves, which, as they closed, fastened on to the intruding limb. On
-one occasion the molluscs did not relax their grasp for days; and had
-this incident occurred when the creatures were at liberty the molluscs
-might have been carried for a considerable distance. If specimens of
-<i>Sphaerium</i> are put into an aquarium containing Prawns of this
-kind, it is probable that before very long the crustaceans will have
-one or two attached to some of their limbs.</p>
-
-<p>Prawns are exceedingly beautiful, and if we get hold of live specimens,
-from salt water or fresh, they should be put into an aquarium&mdash;the
-smaller, in reason, the better&mdash;so that their motions may be watched
-with the hand lens. If much weed be put in, the Prawns will use their
-walking legs in preference, while if there is little vegetation the
-powerful tail-fan will be employed for motion backwards, while the five
-pairs of limbs on the abdomen enable their owners to move forwards
-through the water.</p>
-
-<p>From Fig. 66 one may get a good notion of a Prawn, and of the points
-in which Prawns, in<span class="pagenum" id="Page_132">[132]</span> the zoological sense of the word, differ from
-Shrimps. The head of the Prawn is armed in front with a long blade-like
-beak, studded along its upper and lower edges with a series of teeth
-like those of a saw, and the second leg is chelate, that is, armed with
-pincers, resembling, in miniature, that of a lobster or crab. In the
-Shrimp, on the contrary, there is scarcely a trace of the beak, and
-the first leg is incompletely chelate, or sub-chelate<a id="FNanchor_45" href="#Footnote_45" class="fnanchor">[45]</a> (Fig. 67),
-its last joint folding back upon the one that supports it, just as the
-blade of a pocket-knife closes on its handle. These two distinctions
-hold good between all Prawns and all true Shrimps.</p>
-
-  <div class="figcenter" id="i_132" style="width: 350px">
-     <img
-    class="p2"
-    src="images/i_132.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 66.</span>&mdash;Prawn.</p>
-  </div>
-
-<p>Now let us go over our Prawn&mdash;a spirit specimen&mdash;in detail. The
-antennae may be separated, and examined, and the appendages of the
-inner pair distinguished, for at first it may be thought that there
-are more than two pairs. This, however, is not the case, as should be
-ascertained by actual investigation. A needle inserted at the base of
-the outer antennae will separate the first three<span class="pagenum" id="Page_133">[133]</span> segments, bearing
-respectively the eyes, and the first and second pairs of antennae.
-The eye should be carefully looked at to make out that it is really
-compound. Then the joints of the antennae, each with its circle of
-sense-hairs, are to be noticed. Last of all, the inner pair of antennae
-deserve attention, for these carry in the basal joint an organ of
-hearing. This joint is large and sac-like, and contains an opening
-through which grains of sand are introduced by the animal itself. The
-grains serve to transmit the vibrations of the water in the sac to the
-auditory hairs, to each of which a branch is sent off from the auditory
-nerve. If the joint is opened the sand will be found. The first
-antennae of a lobster or crayfish may also be examined and compared.</p>
-
-<p>The mouth organs, of which there are six pairs, will offer some
-difficulty, and for this reason it may be well to pass them over in
-this case and to deal with these organs generally when treating of the
-Crab.</p>
-
-<p>Beneath the outer foot-jaws are the first pair of walking feet, which
-are used as cleansing organs. Gosse describes them as ‘beset with hairs
-which stand out at right angles to the length of the limb, radiating in
-all directions like the bristles of a bottle-brush.’ If we watch our
-Prawn in life, we shall frequently see these limbs in active operation.
-They are brought to bear on every part of the body within reach.
-Sowerby says<a id="FNanchor_46" href="#Footnote_46" class="fnanchor">[46]</a>: ‘The prawn loves to be clean, and he takes surprising
-pains to keep himself so. Drawing up his tail and abdomen, he subjects
-their under surface to the most careful revision, scrubbing and poking
-between the lappets<span class="pagenum" id="Page_134">[134]</span> of the shell and body, diving into every crevice,
-and with the pincer-hand picking out every speck too large to brush
-away.’ The next pair of legs are also chelate; but the three following
-pairs are armed with claws, and it is upon the points of these that the
-animal walks on the bottom. The pincers of the second pair of legs are
-used to pick up food and bring it up to the mouth organs, where it is
-taken by the outer foot-jaws, and passed into the mouth. The swimming
-feet carry two branches, finely fringed with hairs.</p>
-
-  <div class="figcenter" id="i_134" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_134.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 67.</span> First walking leg of Shrimp
-(enlarged).</p>
-  </div>
-
-<p>If the carapace be removed the gills at the base of the walking feet
-will be exposed. These consist of thin leaf-like plates attached to a
-central stalk, and they are aërated by water passing in behind and out
-in front.</p>
-
-<p>After what has been said of the Prawn, little space need be devoted
-to the Shrimp, for it may be gone over in precisely the same way. It
-will be sufficient to call attention to the difference in the antennae,
-to the rudimentary rostrum or beak, and to emphasize the distinction
-between the terminal joints of the first leg in the two creatures. The
-leg shown in Fig. 67 corresponds to the limb used for cleansing by the
-Prawn.</p>
-
-<p>There is a great difference in their habits, for Shrimps burrow in the
-sand for concealment. In doing this the swimming feet, as well as the
-walking legs, are brought into action, and when the Shrimp is settling
-down, sand is swept over its back by the antennae, to render the
-concealment complete.</p>
-
-<p><span class="pagenum" id="Page_135">[135]</span></p>
-
-<p>In many of the rock-pools round the coast, and also in brackish water,
-Mysis, or the Opossum Shrimp, may be met with. It is not, so far as my
-experience goes, a good inmate of the aquarium, but it is extremely
-interesting from the fact that, unlike its higher relations, the
-auditory apparatus is not situated in the antennae, but in the plates
-of the telson (Fig. 68<span class="allsmcap">E</span>).</p>
-
-  <div class="figcenter" id="i_135" style="width: 450px">
-     <img
-    class="p2"
-    src="images/i_135.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 68.</span>&mdash;Mysis, or the Opossum Shrimp.</p>
-  </div>
-
-<p>Mysis is shrimp-like in general appearance but differs from Shrimps
-in the structure of the legs, in the absence of gills, and in other
-particulars.</p>
-
-<p>The telson consists of five pieces. In each of the two inner and
-smaller pieces is an oval sac, like that described in the basal joints
-of the first antennae of the Prawn, containing a single lens-shaped
-otolith, consisting of chalky matter embedded in some organic substance.</p>
-
-<p>‘The vibration of the hairs [in this sac] is mechanical, not depending
-on the life of the<span class="pagenum" id="Page_136">[136]</span> animal. Hensen took a Mysis, and fixed it in such
-a position that he could watch particular hairs with a microscope. He
-then sounded a scale; to most of the notes the hairs remained entirely
-passive, but to some one it responded so violently and vibrated so
-rapidly as to become invisible. When the note ceased the hair became
-quiet; as soon as it was re-sounded, the hair at once began to vibrate
-again. Other hairs, in the same way, responded to other notes. The
-relation of the hairs to particular notes is probably determined by
-various conditions; for instance, by the length, thickness, &amp;c.<a id="FNanchor_47" href="#Footnote_47" class="fnanchor">[47]</a>’</p>
-
-<p>We shall not be able at present to repeat Hensen’s experiment, but we
-may break up the sac and extract the otolith, which may be seen with
-the lenses at our command.</p>
-
-<p>Small specimens of the Shore Crab (<i>Car´cinus mae´nas</i>) are fair
-game for us. They will interest us while living in the aquarium, and
-when dead we can put them into pickle, and break them up at our leisure.</p>
-
-<p>The broad shell of the Crab&mdash;the crab-cart of children&mdash;corresponds
-to the carapace of the Lobster, the Prawn, and the Shrimp, and bears
-the same number of appendages&mdash;fourteen pairs. To make out the pleon
-or swimming part, it is only necessary to lay the crab on its back,
-and, with a needle, or small knife, turn back the flap&mdash;or ‘apron,’
-as fishermen call it&mdash;which lies in a groove on the under surface.
-Here we shall find the pleopods, or swimming feet, though they are not
-really used for that purpose. The eyes, the two pairs of antennae,
-and the five pairs of walking legs<span class="pagenum" id="Page_137">[137]</span> will offer no difficulty. It is
-only necessary to remark that the terminal joints of the last pair of
-walking legs are flattened and fringed with hair, showing some approach
-to the swimming crabs, which use those organs to swim with.</p>
-
-<p>Now we may examine the mouth organs, of which there are six pairs.
-To do this, the crab may be fixed, with the back downwards, or held
-lightly but firmly in the left hand. The latter plan is perhaps the
-more convenient. The index and middle fingers should support the
-carapace, and the thumb should be placed on the pleon. The outer pair
-of mouth organs are the third maxillipedes, or jaw-feet. These close
-the area of the mouth, somewhat after the fashion of the double-doors
-of a cupboard, though the hinging, of course, is different. To open
-these jaw-feet, a needle should be inserted at the top, with a gentle
-pressure downwards and outwards. The back of the crab is turned away
-from us, so that the left jaw-foot should be pressed outwards to the
-right, and the right jaw-foot to the left.</p>
-
-<p>Theoretically these limbs consist of the same number of joints as
-the perei´opods or walking legs; and this is to be borne in mind,
-even if we do not succeed&mdash;and we probably shall not&mdash;in tracing the
-full number of seven joints. But we may notice and count the terminal
-joints, and observe the fringing of the limb with hair.</p>
-
-<p>A similar method of using the needle will enable us to raise the second
-and first pairs of maxillipedes, which are of smaller size and softer
-structure.</p>
-
-<p>Having raised these organs, it is well to replace them&mdash;to close the
-doors, as it were&mdash;and then to raise them again, to observe how they
-work. They<span class="pagenum" id="Page_138">[138]</span> may then be detached and fastened to a small piece of card,
-for comparison with similar organs in the lobster and the crayfish, and
-with the mouth organs of insects.</p>
-
-<p>Beneath the maxillipedes are the second and first maxillae&mdash;thin,
-leaf-like organs. The first-named are furnished with spoon-like scoops,
-which serve to carry out from the gill-chamber the water that has
-parted with its oxygen in aërating the gills.</p>
-
-<p>Immediately below the maxillae lie the mandibles, with hard, cutting
-edges, by means of which the food is broken up. Each carries a palp.</p>
-
-  <div class="figcenter" id="i_138" style="width: 450px">
-     <img
-    class="p2"
-    src="images/i_138.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 69.</span>&mdash;Maxillipedes and Maxilla (<i>b</i>)
-of Shore Crab. (<i>d</i>) First maxillipede. (After Savigny.)</p>
-  </div>
-
-<p>These inner three pairs should also be detached, and the whole of the
-mouth organs arranged on a card thus:&mdash;</p>
-
-<div class="parent">
-<ul class="left">
-  <li class="smcap">Mandibles.</li>
-  <li class="smcap">First Maxillae.</li>
-  <li class="smcap">Second Maxillae.</li>
-  <li class="smcap">First Maxillipedes.</li>
-  <li class="smcap">Second Maxillipedes.</li>
-  <li class="smcap">Third Maxillipedes.</li>
-</ul>
-</div>
-
-<p>The first attempt will certainly be unsuccessful; and the first few
-attempts will probably be unsatisfactory; but we shall gain knowledge
-with each successive trial. And knowledge is worth the winning.</p>
-
-<p><span class="pagenum" id="Page_139">[139]</span></p>
-
-<p>The stomach is interesting, and the gastric mill may be easily
-examined. When the mouth organs are removed, there will be no
-difficulty in taking out the stomach. This should be cut open with a
-needle, and then we shall see the gastric teeth (<i>g</i> <i>g</i>)
-which grind up the food against the fixed calcareous plate (<i>b</i>
-<i>b</i>). The lower end of the stomach is set with fine hairs, which
-prevent the passage of food into the intestines until it has been
-ground fine between these living millstones. A similar arrangement is
-found in all the higher Crustacea. The time spent in comparing the
-gastric mill of the Crab with the ‘gizzard’ of the Cockroach will not
-be thrown away.</p>
-
-<p>The Broad-clawed Porcelain Crab (<i>Porcella´na platyche´les</i>) is
-also worth keeping, for it is a droll little creature. These crabs
-are generally to be found clinging to the under surface of stones or
-of ledges of rocks overhanging small pools. The chief interest of
-these crabs, for us, lies in the exceedingly beautiful arrangement for
-procuring food with which the outer pair of foot-jaws is furnished.</p>
-
-  <div class="figcenter" id="i_139" style="width: 408px">
-     <img
-    class="p2"
-    src="images/i_139.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 70.</span>&mdash;Stomach of Crab laid open. <i>b</i> <i>b</i>
-<i>b</i>, fixed plate, against which the gastric teeth <i>g</i>
-<i>g</i> are opposed; <i>b´</i> <i>b´</i>, gastric teeth
-enlarged.</p>
-  </div>
-
-<p>‘Watching a Broad-claw beneath a stone close to the side of my tank, I
-noticed that his long antennae were continually flirted about; these
-are doubtless sensitive organs of touch, or some analogous sense,
-which inform the animal of the presence, and perhaps of the nature,
-of objects<span class="pagenum" id="Page_140">[140]</span> within reach. At the same time I remarked that the outer
-foot-jaws (pedipalps) were employed alternately in making casts, being
-thrown out deliberately, but without intermission, and drawn in,
-exactly in the manner of the fringed hand of a Barnacle, of which both
-the organ and the action strongly reminded me. I looked at this more
-closely with the aid of a lens: each foot-jaw formed a perfect spoon
-of hairs, which at every cast expanded and partly closed. That you may
-understand this better, I must say that the foot-jaw resembles a sickle
-in form, being composed of five joints, of which the last four are
-curved like the blade of that implement. Each of these joints is set
-along its inner edge with a row of parallel bristles, of which those
-of the last joint arch out in a semicircle, continuing the curve of
-the limb; the rest of the bristles are curved parallel or concentrical
-with these, but diminish in length as they recede downwards. It will be
-seen, therefore, that when the joints of the foot-jaw are thrown out,
-approaching to a straight line, the curved hairs are made to diverge;
-but as the cast is made they resume their parallelism, and sweep in, as
-with a net, the atoms of the embraced water<a id="FNanchor_48" href="#Footnote_48" class="fnanchor">[48]</a>.’</p>
-
-<p>All this description may be verified from a spirit specimen, if the
-foot-jaws be carefully removed. And the examination with the lens will
-also show that these hairs are plumose, that is, set with smaller hair,
-like the barbs of a feather.</p>
-
-<p>At this point we may conveniently take leave of the Stalk-eyed, and
-pass on to the Sessile-eyed, Crustacea. Leaving the Cuma´cea out
-of the<span class="pagenum" id="Page_141">[141]</span> question, we have two Sub-orders from which to choose our
-subjects&mdash;the Amphip´oda and the Isop´oda&mdash;conveniently Englished,
-Am´phipods and I´sopods. We learn from Mr. Stebbing<a id="FNanchor_49" href="#Footnote_49" class="fnanchor">[49]</a> that ‘the
-Amphip´oda, which are common in fresh as well as in salt water, were
-so named by the French naturalist Latreille, as having feet extending
-in all directions, their limbs at the same time having much diversity
-of form, in correspondence with diversity of function. The Isop´oda,
-or equalfooted animals, besides being found both in fresh and salt
-water, have more decidedly than the Amphip´oda extended their range
-to the dry land. The name was invented by Latreille in ignorance of
-the great number of species, since investigated, in which the feet are
-strikingly unlike and unequal. Nevertheless, the name may stand, just
-as a rose remains a rose even when it is not rose-coloured.’ These last
-two sentences must be borne in mind, for they throw great light on a
-subject that may give us some trouble&mdash;the question of priority in
-nomenclature.</p>
-
-<p>The majority of the Amphipods live in salt water, but a few are found
-in ponds and streams, and some dwell on the shore, near, but not in,
-the sea. The animals of this Sub-order are distinctly segmented, and
-three regions may be distinguished thus <img src="images/i_141.jpg" alt=""
-style="height:2em; vertical-align: middle;" /> where C stands for
-the Cephalon, or head, Per. for the Perei´on, or body, and Pl. for
-the Ple´on (literally, the swimming part), or tail. On the head we
-shall find two pairs of antennae, the eyes, and the mouth appendages.
-Each segment of the perei´on bears<span class="pagenum" id="Page_142">[142]</span> a pair of appendages; the first
-two pairs are called respectively the first and second gnath´opods
-(or jaw-feet), and the other five pairs perei´opods, or walking feet.
-The pleon carries three pairs of ple´opods, or swimming feet, on the
-first three segments, and each of the following three has a pair of
-uropods or tail appendages. It is well to make out these parts in every
-specimen that comes in our way. More is learnt by breaking up one
-specimen than by reading the clearest description so often that one
-knows it by heart.</p>
-
-  <div class="figcenter" id="i_142" style="width: 350px">
-     <img
-    class="p2"
-    src="images/i_142.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 71.</span>&mdash;Gammarus. (After Sars.)</p>
-  </div>
-
-<p>We may begin with the Fresh-water Shrimp (<i>Gam´marus pulex</i>),
-which may be taken abundantly in running water where there is plenty
-of vegetation. Willow-moss affords these Crustaceans<span class="pagenum" id="Page_143">[143]</span> a favourite
-hiding-place. It is an excellent plan to gather a quantity of
-weed and shake it over a newspaper or a piece of mackintosh. The
-‘Shrimps’&mdash;which, by the way, are not really Shrimps&mdash;will be dislodged
-from the weed, and we shall see them wriggling along on their sides,
-from which habit they and their near relatives are often called
-‘Scuds,’ and ‘Screws.’ They are useful inmates of an aquarium, because
-they feed on decaying animal matter, and so keep the water pure and
-sweet. Opinions are divided as to whether these animals feed on
-water-plants; it is probable that when their natural food fails them,
-they take what comes in their way. I have kept marine and fresh-water
-species of Gammarus (the genus to which the Fresh-water Shrimp belongs)
-in tanks which contained no other animals, but plenty of vegetation,
-and both lived and did well for a considerable time. They are by no
-means unwilling to make a meal off the dead body of one of their own
-species; but it is exceedingly doubtful if they prey on each other, as
-some old writers have asserted. This notion probably arose from the
-fact that the male carries the female, which is much smaller, about
-with him, during the period of courtship, holding her tightly beneath
-his body by means of the fingers of its first two pairs of hands. The
-habit is not confined to this genus, nor even to this Sub-order; for
-some, if not all, the species of Idotea carry on their courtship in
-similar fashion, as does also the Water Woodlouse. For the verification
-of statements such as these, a small aquarium is necessary, but the
-animals will not be under observation long before the observer will be
-convinced of their truth.</p>
-
-<p><span class="pagenum" id="Page_144">[144]</span></p>
-
-<p>All species of Gammarus, whether living in the sea or fresh water,
-may be readily distinguished by the rows of small spines on the three
-hinder segments of the pleon, for this is one of the characteristic
-marks of the genus. After we have kept specimens in the aquarium for
-a time, so as to become familiar with their general appearance and
-habits, we will put them to practical use by breaking them up.</p>
-
-<p>Our first task is to work over the animal as a whole, and to make
-out the three regions&mdash;ceph´alon, or head; pereī´on, or body; and
-plē´on, or swimming part, or tail&mdash;into which it is divisible. It
-will not be sufficient to do this once, and then to imagine we have
-the whole matter fixed in our memory. It should be repeated over and
-over again, with every specimen that comes into our hands, till we know
-these regions practically, and the number and kind of appendages they
-carry. And then the three rows of spines are to be looked for. For all
-this the inch lens will be quite sufficient.</p>
-
-<p>Now let us separate the head. When this is done, and if we use the
-lens, we shall at once be able to account for the name ‘Sessile-eyed
-Crustacea,’ for the difference between the eyes of our specimen and
-those of a shrimp or a crab will be evident. Nor can there be any doubt
-that they are compound eyes, though the outer integument is not divided
-into facets. The antennae are next to be considered. Of these there
-are two pairs, the superior, or inner, pair being the longer. These
-antennae consist of three basal joints and a many-jointed flagellum,
-or lash, and on each of the inner pair is a secondary appendage,
-arising from the distal (or outer) end of the third basal joint. We<span class="pagenum" id="Page_145">[145]</span>
-may represent one of the superior antennae thus: <img src="images/i_145.jpg" alt=""
-style="height:1em; vertical-align: middle;" />. The dashes
-represent the three basal joints, the long row of dots the many-jointed
-flagellum, and the slanting row of dots stands for the secondary
-appendage. The sensory-hairs on the joints of the flagellum should be
-looked for, and may be made out with the inch lens. The same power will
-show the denticle, or tooth-like projection at the base of the lower
-antennae.</p>
-
-<p>Next come the mouth parts. As compared with Crabs, Amphipods seem badly
-off in this respect; for the second and third maxillipedes of the
-former become the first and second gnathopods of the latter, so that
-instead of six pairs of mouth organs the Amphipods have only four.</p>
-
-<p>It is not an easy matter for a beginner to separate the mouth parts
-of an Amphipod, but the difficulty is not insuperable, and will grow
-‘small by degrees and beautifully less’ with practice. We have to make
-out four pairs of organs arranged in the order given at the side of the
-page, the mandibles being the innermost.</p>
-
-<div class="parent">
-<ul class="left">
-  <li class="smcap">Mandibles.</li>
-  <li class="smcap">First Maxillae.</li>
-  <li class="smcap">Second Maxillae.</li>
-  <li class="smcap">Maxillipedes.</li>
-</ul>
-</div>
-
-<p>Of course we must begin with the maxillipedes (Fig. 72). The specimen
-may be held between the finger and thumb, and the parts picked out with
-a needle. It is, however, better and easier to make the dissection
-under water. Then we can remove the second and first maxillae, the
-latter easily recognizable by its palp or feeler. Last of all come the
-mandibles, also bearing a palp. We shall <i>feel</i> these under the
-needle, because of their hardened cutting edges. These are distinctly<span class="pagenum" id="Page_146">[146]</span>
-toothed. When practice has made the separation of these parts fairly
-easy, they should be compared with the mouth parts of other members of
-the group, so as to utilize the knowledge we have gained.</p>
-
-  <div class="figcenter" id="i_146" style="width: 300px">
-     <img
-    class="p2"
-    src="images/i_146.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 72.</span>&mdash;Maxillipedes of <i>Gammarus
-marinus</i> (in centre). <i>A.</i> First maxilla. <i>B.</i> Second
-maxilla (magnified).</p>
-  </div>
-
-<p>Next come the two pairs of gnathopods, and in these we have to find
-seven joints&mdash;which may be denoted by the numbers 1, 2, 3, 4, 5, 6, 7;
-1 being the basal joint, or that nearest the body. The sixth joint is
-often called the ‘hand,’ and the seventh, the ‘finger.’ The joints vary
-greatly in different genera. The walking legs are next to be examined,
-and we may notice that the first and<span class="pagenum" id="Page_147">[147]</span> second pairs are turned forwards,
-and the third, fourth, and fifth pairs backwards. At the bases of these
-legs are the breathing apparatus, and the females have leaf-like plates
-on the anterior four pairs, forming a pouch in which the eggs are
-hatched, and here she shelters her young, and carries them about with
-her.</p>
-
-<p>The following account of this habit is taken from Bate and Westwood’s
-<i>Sessile-eyed Crustaceae</i> (i. pp. 380, 381), and was furnished to
-the authors of that book by Dr. James Salter: ‘On catching a female
-with live larvae, nothing is seen of the progeny till the parent has
-become at home in the aquarium, when the little creatures leave her
-and swim about in her immediate neighbourhood. The plan I have adopted
-to watch this curious habit of maternal protection, has been to place
-a single individual in a bottle of sea water. After a time, and that
-soon, the little crustacean seems at ease and swims slowly about,
-when the young fry leave her and swarm around her in a perfect cloud;
-they never leave her for more than half or three-quarters of an inch,
-and as she slowly moves about they accompany her. If now one taps the
-side of the bottle with one’s finger-nail, the swarm of larvae rush
-under their parent, and in a second are out of sight. The parent now
-becomes excited, and swims about quickly, as if trying to escape;
-but by letting the bottle containing her rest quite still she soon
-gets composed, when out come the young larvae again and swim about
-as before. This may be repeated as often as the observer wishes, and
-always with the same result. I have only seen this in one species, but
-it is quite a common species in Poole Harbour, and I have watched the
-interesting habit many times.’</p>
-
-<p><span class="pagenum" id="Page_148">[148]</span></p>
-
-<p>The swimming legs are, roughly speaking, <img src="images/i_148a.jpg" alt=""
-style="height:1em; vertical-align: middle;" />shaped&mdash;that is, they
-consist of a stem, carrying two many-jointed filaments, fringed with
-fine plumose hairs. A hair is said to be plumose when it bears smaller
-and finer hairs on each side. ‘By folding the tail beneath the body,
-and suddenly striking it out again, those animals which exist in the
-water, as well as those which live on the shore, are enabled to dart or
-leap to a considerable distance<a id="FNanchor_50" href="#Footnote_50" class="fnanchor">[50]</a>.’</p>
-
-  <div class="figcenter" id="i_148" style="width: 400px">
-     <img
-    class="p2"
-    src="images/i_148.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 73.</span>&mdash;Nest-building Amphipod. (From life.)</p>
-  </div>
-
-<p>Our hand lens may be well employed in watching some of the
-nest-building Amphipods at work in the aquarium. There can be no
-difficulty in keeping these creatures in captivity, and under<span class="pagenum" id="Page_149">[149]</span>
-observation, as they build their tubes and rear their families. They
-are plentiful in every rock pool round the coast, and it would be a
-hard matter to dip the net into any such pool without getting a few
-specimens.</p>
-
-<p>They need absolutely no care. The aquarium of the specimen figured
-was a four-ounce bottle, tightly corked; and in it was a spray of
-Cladophora, on which the animal fed, and the growth of which broke up
-the carbon dioxide and set free good store of oxygen. Here it lived for
-some months, and built more than one tube for itself against the side
-of the bottle.</p>
-
-<p>It is easy enough through the pocket lens to watch the Amphipod at
-work. Like other builders, the first thing it does is to get its
-materials ready. Lying on its side, with its back against the glass,
-it will rake together with its antennae and jaw-feet a good store of
-vegetable <i>débris</i>, or if there be no supply of this, will break
-off branches from the growing weed.</p>
-
-<p>But gathering vegetable <i>débris</i>, or even filaments of living
-weed, is very far from being tube-building. Something more is needed
-to bind the mass into a coherent structure. This the animal itself
-supplies. The bases of the first two pairs of walking feet are large,
-and contain glands which secrete a glutinous cement, that can be spread
-like mortar, or spun out into threads.</p>
-
-<p>An American observer devoted much time to the observation of these
-animals. He says<a id="FNanchor_51" href="#Footnote_51" class="fnanchor">[51]</a>: ‘When captured and placed in a small zoophyte
-trough, with small branching algae, the individuals almost always
-proceeded at once to construct a tube, and<span class="pagenum" id="Page_150">[150]</span> could very readily be
-observed under the microscope.... The branches were not usually at once
-brought near enough together to serve as the framework of the tube, but
-were gradually brought together by pulling them in and fastening them
-a little at a time until they were brought into the proper position,
-where they were firmly held by means of a thick network of fine threads
-of cement spun from branch to branch. After the tube had assumed
-very nearly its completed form, it was still usually nothing but a
-transparent network of cement-threads woven among the branches of the
-weed.’</p>
-
-<p>Then he describes the method in which the Amphipod works up bits
-of weed and its own droppings into the framework of the tube. In
-putting its foecal pellets to this use, it reminds one of a species of
-Melicerta (<i>Melicerta janus</i>)<a id="FNanchor_52" href="#Footnote_52" class="fnanchor">[52]</a>, which employs the same material
-to coat its gelatinous sheath.</p>
-
-<p>In breaking up weed and pellets with its foot-jaws and (probably) its
-mandibles, the Amphipod recalls the practice of some of the Masking
-Crabs, which have been seen to apply to the mouth the material they
-were using to deck themselves. Dr. Aurivillius suggests that in the
-case of the Crabs there may be an adhesive secretion from the mouth,
-as there is possibly in the Amphipods. ‘The spinning was done wholly
-with the first and second pereiopods, the tips of which were touched,
-from point to point over the inside of the skeleton tube, in a way
-that recalled strongly the movements of the hands in playing upon a
-piano. The cement adhered at once to the points touched, and<span class="pagenum" id="Page_151">[151]</span> spun out
-between them in uniform delicate threads. The threads seemed to harden
-very quickly after they were spun, and did not seem, even from the
-first, to adhere to the animal itself. In one case, in which the entire
-construction of the tube was watched, the work was apparently very
-nearly or quite completed in little more than half an hour.’</p>
-
-<p>The species we are likely to meet with in rock-pools fashion their
-tubes in a similar way. The only difference to be noted is that they
-employ less cement, and a larger proportion of broken-down weed and
-other matters.</p>
-
-<p>The Sand-hopper (<i>Tali´trus locus´ta</i>) and the Shore-hopper
-(<i>Orches´tia littorea</i>) are so exceedingly plentiful that it may
-be well to collect and preserve some during any visit to the seaside.
-Both are of fairly large size, and present no great difficulty to us in
-making out their several parts. Let us take the Sand-hopper first.</p>
-
-<p>Sand-hoppers swarm on most sandy shores, where they perform the useful
-part of scavengers. They are always found above high-water mark, and
-do not enter the sea of their own accord. In hunting for them it is a
-good plan to turn over decaying masses of sea-weed, for under them the
-Sand-hoppers are sure to swarm.</p>
-
-<p>Strange tales have been told of their voracity. Bate and Westwood<a id="FNanchor_53" href="#Footnote_53" class="fnanchor">[53]</a>
-record the story of a correspondent who says that at Whitsand he ‘saw
-“not millions, but cartloads,” of this species lying piled together
-along the margin of the sea. They hopped and leaped about, devouring
-each other, as if for very wantonness. A handkerchief, which a lady let
-fall amongst them, was soon reduced to a piece<span class="pagenum" id="Page_152">[152]</span> of open work by the
-minute jaws of these small creatures.’</p>
-
-<p>This statement has been copied into a good many books, without
-criticism. At last Mr. David Robertson tried various experiments with
-a view to discover if these creatures would feed on each other, or,
-failing other food, put up with cambric or muslin. The specimens upon
-which he made his observations did neither the one nor the other. Mr.
-Robertson embodied the results of his experiments in a paper which he
-read before the Natural History Society of Glasgow<a id="FNanchor_54" href="#Footnote_54" class="fnanchor">[54]</a>. And the story
-may be read in an abbreviated form in the Rev. T. R. R. Stebbing’s
-<i>Naturalist of Cumbrae</i>, p. 329.</p>
-
-<p>In Gammarus we have a standard with which to compare our Sand-hopper.
-The first thing to notice is the difference in the antennae. Here the
-superior pair are very short, and carry no secondary appendage, and
-the lower pair have no denticle or tooth-like process. There is also
-considerable difference in the gnathopods, or jaw-feet, the sixth joint
-of which, in the Sand-hopper, does not form a ‘hand.’ The pleopods, or
-swimming feet, are small, and are used for leaping. We shall also find
-some difference in the details of the mouth parts, especially in the
-toothing of the mandibles.</p>
-
-<p>We now come naturally to the Isop´oda, which are distinguished by the
-nearly uniform size of the seven segments which constitute the trunk,
-and the seven pairs of limbs borne by these segments. The head is
-distinct, and the breathing apparatus is carried on the under side of
-the pleon&mdash;in these animals not the ‘swimming’ part&mdash;five pairs of<span class="pagenum" id="Page_153">[153]</span>
-plates lying one over another, sometimes covered by a larger outer pair.</p>
-
-<p>A normal I´sopod may be represented <img src="images/i_153a.jpg" alt=""
-style="height:.5em; vertical-align: middle;" />, where the
-small dash will stand for the cephalon, or head; the seven dots for the
-segments of the perei´on, and the long dash for the pleon.</p>
-
-<p>The Common Asellus (<i>Asellus aquaticus</i>) of ponds and ditches
-is an excellent subject. It lives well in confinement, and if the
-conditions are fairly favourable, will increase and multiply. These
-animals will forage for themselves, and pick up a comfortable living
-from the vegetable <i>débris</i> that always accumulates at the bottom
-of an aquarium, and they are not averse from an occasional meal of
-animal food.</p>
-
-  <div class="figcenter" id="i_153" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_153.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 74.</span> Water Woodlouse.</p>
-  </div>
-
-<p>While our specimens of Asellus are moving about in any convenient
-vessel, we may verify with the hand lens what has been said about the
-general form. Then we may notice the antennae, the inner pair being
-much the smaller. There can be no difficulty in discriminating the head
-and the eyes; the seven segments of the perei´on, each bearing a pair
-of limbs; and the pleon with its two terminal appendages. These last
-consist of a stalk bearing two longer filaments, armed with spines, and
-ending in a small pencil of hairs.</p>
-
-<p>It is easy to see that the segments of the pleon have coalesced, so as
-to form a continuous plate or shield on the upper surface.</p>
-
-<p>If we now take our dissecting microscope and place an Asellus in some
-water in an excavated 3 in. by 1 in. slip on the stage, examination
-with an<span class="pagenum" id="Page_154">[154]</span> inch lens will show us a considerable amount of detail. With
-the half-inch Leitz lens (see p. 18) one may see quite clearly the
-beautifully annulated form of the flagella of the antennae, the sensory
-hairs with which these organs are set, and the circulation of the blood
-in the limbs and the antennae&mdash;the corpuscles moving in a continuous
-stream. More than this: we shall be able with the same power to
-distinguish tufts of Vorticellids that settle on the Asellus, and the
-commensal rotifers that roam about on the body of their host, generally
-on the limbs and under surface.</p>
-
-<p>Now we may turn the Asellus on its back, to examine the breathing
-apparatus more closely than we were able to do when the creature was
-moving about in the bottle. It will be easy to make out the opercular
-plates&mdash;modified tail appendages&mdash;that open and shut to admit water to,
-or allow it to flow out from, the true breathing-plates which function
-as gills, and correspond to the swimming feet of the Amphipods.</p>
-
-<p>In the female there is a pouch beneath the perei´on, in which the eggs
-are carried till they are hatched, and which serves as a nursery and
-refuge for the young.</p>
-
-<p>If a good number of these animals be collected they will probably
-breed, and then there will be the opportunity of seeing for ourselves
-the young carried about in the incubatory pouch.</p>
-
-<p>There are two other aquatic I´sopods which will make good subjects for
-us on account of their great abundance, and the ease with which they
-may be kept in any improvised aquarium, with a little weed. They may
-both be taken in brackish water, and will live and thrive in fresh
-water, without any admixture of salt. Indeed, both have<span class="pagenum" id="Page_155">[155]</span> lived for some
-months in a small bottle of New River water, in which the only weed is
-some willow moss. They feed on this and on the vegetable <i>débris</i>
-that accumulates at the bottom of the bottle, and both species have
-bred.</p>
-
-<p>The first is Idot´ea (<i>I. pelag´ica</i>), a long, narrow creature,
-with very short inner antennae. The last four segments of the pleon
-form a plate on the upper surface; and on the under surface the
-opercular plates may be opened like tiny folding-doors, to show the
-breathing plates.</p>
-
-<p>These vary greatly in colour. Of another species, Spence, Bate, and
-Westwood say: ‘According to our experience the colour of the animal is
-dependent upon that of the weed on which it lives. Those that live on
-the black fucus are generally very dark purple, while those that we
-find on the green algae are brightly verdant; and it has always been
-our opinion that this change was due to the food<a id="FNanchor_55" href="#Footnote_55" class="fnanchor">[55]</a>.’</p>
-
-<p>The other little creature is called Sphaero´ma&mdash;it has no English
-name&mdash;from the fact that it can roll itself into a ball. It is not
-difficult to identify, from the fact that all the segments of the pleon
-are joined into one plate, the hinder margin of which is entire, thus
-<img src="images/i_155.jpg" alt=""
-style="height:.5em; vertical-align: middle;" />.</p>
-
-<p>The garden will afford us a hunting-ground for the last specimen of
-this group for which we have space&mdash;the Woodlice. Enough has been said
-of the method of looking over and breaking-up I´sopods generally to
-render detailed description unnecessary. The inner pair of antennae,
-however, are so small as to be readily overlooked: indeed, on first
-sight these creatures seem to have but<span class="pagenum" id="Page_156">[156]</span> a single pair. Some have, and
-others have not, the power of rolling themselves into a ball; and,
-concerning the former, Swammerdam tells the following story:&mdash;</p>
-
-<p>‘One of our maidservants had at one time found a great number of
-Woodlice in the garden, contracted into round balls ..., and thinking
-she had found a kind of coral beads, she began to put them one after
-another on a thread, but it soon happened that these little creatures,
-which roll themselves up in such a manner only for fear of harm, and
-appear as if they were dead, being obliged to throw off their mask,
-resumed their motions. On seeing which, the maidservant was so greatly
-astonished, that she threw away the Woodlice and the thread, and cried
-out, and ran away<a id="FNanchor_56" href="#Footnote_56" class="fnanchor">[56]</a>.’</p>
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_157">[157]</span></p>
-
-<h2>CHAPTER VI<br />
-<span class="subhed">AQUATIC INSECT LARVAE</span></h2></div>
-
-<div>
-<img class="drop-cap" src="images/i_157.jpg" width="50" alt=""  />
-</div>
-
-<p class="drop-cap p-left">In this chapter we shall deal with a few aquatic insect larvae. Of
-these, some are aquatic also in the perfect condition, while others
-emerge from the pupa stage as aërial insects. It requires no great
-amount of care to keep these creatures, and some hints on this subject
-and on collecting are given in the first chapter.</p>
-
-<p>The larva of Dytiscus is abundant during the greater part of the year,
-and is almost sure to be met with by the collector, who will find it
-an extremely interesting object for examination and study. No other
-creatures should be put in the same bottle with these larvae; and if
-there are several of them in one bottle, it is a good plan to put in
-plenty of pondweed, which will often keep them from attacking each
-other.</p>
-
-<p>When full grown, the Dytiscus larva may attain a length of two inches
-or rather more. Its colour is dingy brown, and its aspect forbidding
-enough to justify the uncomplimentary names that have been bestowed
-upon it&mdash;Water-devil and Water-tiger. It certainly rivals the tiger in
-fierceness, and its method of stealing up to its prey and attacking<span class="pagenum" id="Page_158">[158]</span> it
-from behind led Swammerdam to call it the Sicarius or Assassin Worm.</p>
-
-<p>One must not imagine that Swammerdam was ignorant of its nature; ‘worm’
-with him was a general term for any larval form. Indeed, he says,
-‘It is extremely probable that some peculiar species of the Water
-Beetle proceeds from this worm, when, having remained in the water a
-sufficient time, it betakes itself to the land to undergo its mutation;
-but this is mere conjecture.’ What was conjecture for him is fact for
-us.</p>
-
-<p>Now let us put our larva into a small tube, and examine it more
-closely. The head is large and joined to the first segment of the
-thorax by a distinct neck. There are twelve small eyes, six on each
-side, a pair of antennae, two pairs of palps, and a large pair of
-sickle-shaped mandibles, which Swammerdam calls ‘teeth,’ and says that
-‘it is perhaps to contain the muscles such teeth require that Nature
-has made the head so large.’ Behind the head come eleven segments, of
-which the first and last are the longest. They gradually increase in
-width till the sixth, the rest again decreasing, till the eleventh ends
-in a blunt point, from which diverge two appendages, thus <img src="images/i_158.jpg" alt=""
-style="height:1em; vertical-align: middle;" />
-,
-thickly fringed on both sides with hair, as are the tenth and eleventh
-segments.</p>
-
-<p>There are six legs, one pair to each of the first three segments.
-These also carry fringes of hair, thus increasing their power as
-swimming organs; and, in addition, they bear numerous spines, and end
-in strong double claws, which must be of service in climbing over
-aquatic vegetation, and may assist in holding a struggling victim or in
-striking it down, so as to bring it within reach of the mandibles.</p>
-
-<p><span class="pagenum" id="Page_159">[159]</span></p>
-
-<p>Spiracles will be found&mdash;seven on each side. These do not, however, in
-the larval condition, serve as breathing organs, though they fulfil
-their proper office in the pupa. The air-tubes of the larva open at the
-extremity of the last segment. When the larva wants to breathe it comes
-to the surface without an effort, for it is lighter than the water it
-displaces. The tail rises above the surface, and a fresh supply of air
-is taken in. When the larva wishes to descend, a stroke of the tail
-sends it downwards, and as it reaches the bottom of the tube it will
-cling with its claws to any weed we may have put in with it, or hold on
-with them to the glass itself.</p>
-
-<p>The chief interest of this animal lies in its mandibles, and the method
-in which they are employed. It was formerly believed that the mouth of
-this larva was closed, so that it could not take solid food, and that
-it lived entirely on the juices of its prey, which it sucked up through
-its hollow mandibles.</p>
-
-<p>Swammerdam says of this larva, ‘When about to eat he seizes with the
-two teeth (mandibles) the little creatures that come in his way, and
-pierces their body with the sharp crooked points. The teeth being
-perforated from the points to the roots, he in a surprising manner
-sucks through them into his mouth the blood of the unfortunate captive.
-This may be easily seen, especially when the blood of his prey is of a
-red colour, as the teeth are transparent.’</p>
-
-<p>He then describes how he watched one of these larvae feed, and saw the
-blood, mixed with air-bubbles, travel up the mandibles. After this he
-tells us how, if we have a Dytiscus larva, we may ‘procure ourselves
-a very entertaining and surprising<span class="pagenum" id="Page_160">[160]</span> sight, by throwing to it a small
-earthworm; for let this last move, twine, and otherwise bestir itself
-ever so much, the other keeps its hold, and very calmly sucks the blood
-of its prisoner.’</p>
-
-<p>We may, however, go to work in another fashion. We may dissect out the
-mandibles from a dead larva and pass a fine hair into the slit near the
-point, and it will come out at the orifice near the base. It is through
-this orifice that the nutritive juices of the prey are drawn into the
-true mouth. This practical proof that the mandibles are pierced is by
-no means so difficult as one might suppose.</p>
-
-<p>De Geer<a id="FNanchor_57" href="#Footnote_57" class="fnanchor">[57]</a> seems to have been the first to suggest that there must
-be some kind of true mouth, and in support of his suggestion tells us
-that he saw this larva eating up the solid parts of a Water Woodlouse
-(<i>cloporte</i>), after having sucked up its juices. More than this,
-he places the mouth in what has proved to be the true position, though
-he did not solve the mystery as to why it is kept so firmly closed.
-This was done by Mr. Burgess, an American naturalist, from whose
-paper<a id="FNanchor_58" href="#Footnote_58" class="fnanchor">[58]</a> the following particulars are condensed:&mdash;</p>
-
-<p>‘Authors have described this creature as mouthless; and if we examine
-the slit where we should expect the mouth to be, we find that this slit
-ends in a perfectly closed seam. The methods of microscopical research
-were brought into play, and a longitudinal section of the head cut and
-mounted. This showed that the upper and lower lips were locked together
-by a peculiar joint&mdash;the upper coming over and locking into the under
-lip (Fig. 75).’</p>
-
-<p>We may get some idea of this mouth-lock by<span class="pagenum" id="Page_161">[161]</span> placing the fingers of the
-right hand over those of the left, and then bending them.</p>
-
-<p>Mr. Burgess concludes his paper thus: ‘We find that the Water-tiger,
-far from being mouthless, as ordinarily assumed, has in fact a
-very wide mouth, though its lips are closely locked together by a
-dove-tailed grooved joint developed for this purpose. Whether this
-joint can be unlocked by the animal itself is another question, which
-I cannot answer, though De Geer’s observation above quoted makes this
-probable. It is, at all events, easy to open the mouth by manipulation
-with a pair of forceps.’</p>
-
-  <div class="figcenter" id="i_161" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_161.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 75.</span>&mdash;Mouth-lock. <i>m</i>, mouth × 125.
-(After Burgess.)</p>
-  </div>
-
-<p>Professor Miall<a id="FNanchor_59" href="#Footnote_59" class="fnanchor">[59]</a> has verified Burgess’s observations, and carried
-them a step further. He found by actual experiment that ‘the mouth-lock
-acted automatically, opening when the mandibles opened, and closing
-when they closed.’</p>
-
-<p>Both these authorities stand very high. Yet, with all respect to them,
-it will be well to test these statements before accepting them.</p>
-
-<p>Something of this mouth-lock may be seen in any well-prepared slide
-of a Dytiscus larva. If we hold the slide up to the light and examine
-with<span class="pagenum" id="Page_162">[162]</span> a power of 10, we shall see a dark line&mdash;in some cases two nearly
-parallel thinner lines&mdash;running from the base of one mandible to the
-base of the other. The dark line is the closed mouth-lock. The two
-nearly parallel thinner lines are the edges of the lips drawn asunder
-in preparing the specimen or by the pressure of the cover-glass. If we
-get to see this much, we shall have advanced one step.</p>
-
-  <div class="figcenter" id="i_162" style="width: 400px">
-     <img
-    class="p2"
-    src="images/i_162.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 76.</span>&mdash;Dytiscus Larvae.</p>
-  </div>
-
-<p>Next we may verify Professor Miall’s experiment, though not quite in
-his way, for such section-cutting as he speaks of is beyond our powers.
-Larvae as large as possible should be chosen, and killed by dropping
-them into boiling water. The mandibles of one should be allowed to
-remain closed, and those of the other plugged open with pith or a small
-piece of wood&mdash;a bit of a match will serve. By putting each in turn
-into an excavated slip with water, carefully covering this with a plain
-slip, and holding these slips together with an elastic band, we may
-examine the larvae as we did the slide.</p>
-
-<p><span class="pagenum" id="Page_163">[163]</span></p>
-
-<p>The result will be practically the same. Where the mandibles are
-closed, we shall see the dark line; and where they are open, we shall
-see the two thinner ones nearly parallel.</p>
-
-<p>One caution may be necessary. The mandibles bear at the base a
-rounded process, which fits into a chitinous cup. It is not difficult
-to mistake this for the mouth-lock, with which, however, it is not
-connected.</p>
-
-<p>There is still one other method which we may adopt to see the mouth.
-The head of one of these larvae may be cut off, dropped into a strong
-solution of caustic potash, where it should remain for a day or two.
-After washing it well in water, cut it in half lengthways, and turning
-either half upon its side, so as to expose the part cut, examine with
-the pocket lens.</p>
-
-<p>These experiments are by no means difficult. But if carried out step
-by step, it will be easy to understand how the larva can suck out the
-juices of its prey, and how it can open its mouth to swallow some of
-the solid parts.</p>
-
-<p>The larva does not readily change into a pupa in confinement. If,
-however, we wish to rear a beetle, the larva must be plentifully
-supplied with food, and removed from a bottle to a flat dish,
-where earth can be placed against the side so as to rise above the
-water-level. Fig. 77, where a pupa is represented in a bank by the side
-of a pond, will give us a hint how to go to work. The time occupied in
-pupation will vary according to the temperature of the room&mdash;but is
-never less than a fortnight. In the open it is probable that the winter
-is passed in the pupal condition, the perfect insect emerging in the
-spring. Like Land Beetles, it does not assume its dark hue<span class="pagenum" id="Page_164">[164]</span> for some
-days, but its pale skin darkens by degrees.</p>
-
-  <div class="figcenter" id="i_164" style="width: 400px">
-     <img
-    class="p2"
-    src="images/i_164.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 77.</span>&mdash;Pupa of Dytiscus.</p>
-  </div>
-
-<p>The larva of Hydrophilus does not seem to be often taken in this
-country. It would make a capital subject for investigation, and the
-food-supply could be arranged easily enough. The repetition of the
-experiences of Lyonnet, who reared these larvae from the egg, would
-be of great interest. He says that he took about thirty larvae from
-the brood, and fed them with very small water-snails. These they
-devoured in the same way as the larger larvae do. Having seized the
-snail with their mandibles, they bent backwards, and supporting it
-on their back, which served them for a table, eat it there, without
-making any use of their legs to hold their prey. When the supply of
-small snails ran short, they did very well with large ones cut up into
-pieces, and with tadpoles. If, however, food was not supplied to them,
-they fed on each other. But, except when pressed by hunger, they lived
-together peaceably<span class="pagenum" id="Page_165">[165]</span> enough, and seemed to take pleasure in each other’s
-society<a id="FNanchor_60" href="#Footnote_60" class="fnanchor">[60]</a>.</p>
-
-<p>The larva of <i>Limnobia replicata</i>, a Crane-fly allied to, but
-smaller than, the well-known Daddy-longlegs, is another excellent
-subject for investigation. It is not very often taken; perhaps because
-it is not often looked for. But it is common enough, for all that.</p>
-
-<p>In general appearance these larvae resemble small caterpillars covered
-with spines. Some of these are simple and others forked, not much
-unlike the letter <img src="images/i_165.jpg" alt=""
-style="height:1em; vertical-align: middle;" />, with a short stem, and the arms slightly
-curved. There are no feet, and the last segment carries two pairs of
-hooks, one large and the other small. From their position they are
-called anal hooks.</p>
-
-<p>The dykes of the Sussex marshes are an excellent hunting-ground.
-Probably the channels of water-meadows, or any other shallow standing
-water in which aquatic moss grows, would serve the collector’s purpose
-quite as well. And such pieces of water abound all over the country.</p>
-
-<p>For taking these larvae the ordinary net and bottle are of little use,
-though a few may be captured by sweeping backwards and forwards among
-patches of aquatic moss.</p>
-
-<p>There is, however, a far easier and surer method. A good handful of
-the moss should be gathered, and put into a shallow vessel half full
-of water&mdash;a developing-dish answers capitally&mdash;and then shaken to and
-fro or gently stirred with a small piece of stick. The larvae will curl
-into a ring and fall to the bottom, whence they may be picked up and
-dropped into a bottle or other receptacle<span class="pagenum" id="Page_166">[166]</span> to be taken home. A fair
-quantity of moss should be gathered, for this is their favourite food,
-and all larvae are greedy feeders.</p>
-
-<p>Other water-plants, however, do not come amiss to them. Just before
-these lines were written I was examining a bottle in which some of
-these larvae were kept. It contained a few sprays of willow-moss and
-some ivy-leaved duckweed, which floated on the surface. One larva on a
-spray of moss was reaching upward, and it was distinctly seen to feed
-on the duckweed. This must have been from choice, for there was within
-reach plenty of what all observers consider to be its natural food.
-This, too, might have been more easily obtained; for, to reach the
-duckweed, the larva had to hold on to the moss by the anal hooks, and
-extend its body in a fashion analogous to that of the caterpillar of a
-geometer moth, which will hold on to a branch with its fore-legs and
-claspers and maintain the body at an angle of 45°, sometimes for hours
-together. I have also seen them feed on hornwort.</p>
-
-<p>The larva of this small Crane-fly is not at all difficult to keep. It
-is exceedingly hardy, and will survive a great deal of rough treatment.
-In November, 1895, I sent three in a tube&mdash;securely packed, as I
-thought&mdash;to a friend in Yorkshire. A few days afterwards I heard, with
-regret, ‘that the bottle was broken in transit, and that the larvae
-arrived dead.’ Three days later I was gratified by receiving a letter,
-from which the following is quoted: ‘The Limnobia larvae have come to
-life again. I put them into water as soon as they arrived, and after
-lying motionless for many hours they have begun to creep about and
-feed.’</p>
-
-<p><span class="pagenum" id="Page_167">[167]</span></p>
-
-<p>This is excellent testimony to their powers of endurance, but it is
-weak in comparison to that which De Geer supplies<a id="FNanchor_61" href="#Footnote_61" class="fnanchor">[61]</a>.</p>
-
-<p>He was Marshal of the Court of Sweden, and one November, before leaving
-his country house for his official duties at Stockholm, he put four
-of these larvae into a vessel of water, and left them to take their
-chance. The water froze into a solid mass. When he returned in the
-following May he found about half the water thawed, and two of the
-larvae dead. The others, though they had been enclosed in ice all the
-winter, were lively and in good condition. He put them into another
-vessel with fresh water and some aquatic moss, and at once they began
-to move about and commenced to feed. Both pupated by the fifteenth of
-the month, and the perfect fly emerged after six days in the pupal
-stage.</p>
-
-  <div class="figcenter" id="i_167" style="width: 250px">
-     <img
-    class="p2"
-    src="images/i_167.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 78.</span>&mdash;Larva of <i>Limnobia replicata</i>.</p>
-  </div>
-
-<p>The following description of this larva is principally condensed from
-De Geer, whence the figures are also taken. The body is long and
-cylindrical, and divided into eleven segments, of which the first and
-largest is sub-triangular. The second and third segments are shorter
-than the rest.</p>
-
-<p>The head (<i>t</i>) is very small and completely retractile within
-the first segment, the anterior margin of which completely closes
-the orifice, so that, in this condition, the creature appears to be
-headless. The body is covered with spines, some simple and<span class="pagenum" id="Page_168">[168]</span> others
-branched. On the first three segments there are only simple spines;
-but from the fourth to the tenth segment inclusive there are also on
-each segment two forked spines&mdash;that is, fourteen in all. On the last
-segment the spines are simple, and here are also four chitinous hooks,
-one pair much larger than the other. These simple spines carry a white
-vessel, which extends throughout their whole length; but in the forked
-spines there are two such vessels placed side by side in the stem, and
-diverging one to each branch.</p>
-
-<p>He comes to the conclusion that these spines are probably the breathing
-apparatus of the larva, for they are similar to those which he observed
-in an aquatic caterpillar. Walker<a id="FNanchor_62" href="#Footnote_62" class="fnanchor">[62]</a> calls these spines ‘long
-filamentous processes, which appear to be internally supplied with
-air-tubes,’ but he does not seem to have taken the trouble to break up
-a specimen, or he would have been in no doubt as to their real nature.
-This is shown by the fact that the larva never comes to the surface to
-take in a supply of air, but contents itself with the oxygen dissolved
-in the water.</p>
-
-  <div class="figcenter" id="i_168" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_168.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 79.</span>&mdash;Forked spine of Limnobia, enlarged; the dark
-lines show air-tubes.</p>
-  </div>
-
-<p>The pupa is quite as remarkable as the larva, though the breathing
-apparatus does not assume the form of spines, but consists of two
-‘trumpets,’<span class="pagenum" id="Page_169">[169]</span> one on each side of the head, as is the case with the
-pupae of gnats, using that term in a wide sense. The colour is a
-greenish-brown, dotted with black. The abdomen is capable of a good
-deal of motion from side to side; and by this means the pupa can raise
-itself to the surface of the water to take in a supply of air.</p>
-
-<p>De Geer remarked that when the pupa rose for this purpose it lay with
-its body horizontal, having the lips of the trumpets a little above the
-surface. It appeared not to like being placed on its back, because in
-that position the trumpets cannot be raised above the surface. When he
-tried the experiment of putting the pupa back downwards, it wriggled
-over by bending the abdomen.</p>
-
-  <div class="figcenter" id="i_169" style="width: 300px">
-     <img
-    class="p2"
-    src="images/i_169.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 80.</span>&mdash;Pupa case of Limnobia.</p>
-     <p class="p0 sm center">(From a photograph taken at the Yorkshire College, Leeds.)</p>
-  </div>
-
-<p>On the abdomen there are several chitinous hooks, which serve in some
-sort as substitutes for limbs. By their means the pupa can moor itself
-to the stems of aquatic plants; and this is necessary, since its
-specific gravity being less than that of the water it would be always
-at the surface, if it had no such means of anchorage. And of course,
-at the top of the water, it would be exposed to the danger of being
-snapped up by birds.</p>
-
-<p>De Geer’s specimen passed six days in the pupal state, and then emerged
-as a perfect Crane-fly.<span class="pagenum" id="Page_170">[170]</span> My specimens did not emerge till after ten and
-eleven days of pupahood, which seems strange, as they were plentifully
-supplied with food in their larval stage.</p>
-
-<p>The fly is a little more than half an inch long, and may be
-distinguished from the common Daddy-longlegs by the character of the
-wings, which are folded somewhat like those of a wasp, but with this
-difference: that the wings of this fly are folded outward, while those
-of the wasp are folded inwards. When the insect wishes to fly, it opens
-the fold so that the whole wing presents a plane surface, but the fold
-reappears directly the Crane-fly ceases its flight (Frontispiece).</p>
-
-  <div class="figcenter" id="i_170" style="width: 300px">
-     <img
-    class="p2"
-    src="images/i_170.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 81.</span>&mdash;Fore-wing of Bee, showing marginal
-fold (× 7).</p>
-  </div>
-
-<p>De Geer’s allusion to the wing of the wasp might have been extended
-to most of the Hymenoptera, as we may see by examining the fore and
-hind wings of a bee or a sawfly. Dr. Sharp<a id="FNanchor_63" href="#Footnote_63" class="fnanchor">[63]</a> says, ‘The wings [of
-the Hymenoptera] are remarkable for the beautiful manner in which the
-hinder one is united to the anterior one, so that the two act in flight
-as a single organ. The hind wing is furnished with a series of hooks,
-and the hind margin of the front wing is curled over so that the<span class="pagenum" id="Page_171">[171]</span> hooks
-catch on to it. In some of the parasitic forms the wings ... have no
-hooks. The powers of flight, in these cases, are probably but small.’</p>
-
-<p>If we were taking our subjects in consecutive order, the larva of
-Ptychoptera would properly come here, as being that of a Crane-fly. But
-since it will be convenient to examine another larva which resemble
-Limnobia in its breathing apparatus, we will take next the larva of
-<i>Parap´onyx stratiota´ta</i>, one of the China Marks, for it is
-extremely interesting and by no means hard to come by.</p>
-
-<p>The China Marks are small moths, with white wings bearing dark
-markings, which have been supposed to resemble Chinese characters.
-Their larvae are aquatic in varying degree&mdash;that is, some breathe air
-in the usual way, by means of spiracles; while others, by means of
-gills, breathe the oxygen dissolved in the water.</p>
-
-<p>Many collectors have, no doubt, taken these larvae, and cast them away
-in the belief that they were caddis-worms. Such was the experience of
-the Rev. Gregory Bateman, the author of <i>Fresh-water Aquaria</i>,
-who says (p. 259): ‘While hunting for fresh-water animals, one not
-seldom comes across an insect wrapped up in two or more green leaves,
-or pieces of leaves, of some aquatic plant. The leaves and the animal
-have somewhat the appearance of a caddis-worm in its case; in fact, for
-a time, before I knew what it was, I mistook it (and I daresay others
-have done so also) for a caddis-worm.’</p>
-
-<p>The cases are usually, but not invariably, made from the food-plant
-of the insect. Mr. Bateman has noted that these larvae ‘do not
-always confine themselves to the same weed, either for food or<span class="pagenum" id="Page_172">[172]</span> for
-building material.’ This has also been my experience. A larva of the
-Brown China Mark, recently taken on the Norfolk Broads&mdash;an excellent
-collecting ground for aquatic larvae&mdash;was put into a tube. The case
-had been damaged, and the only vegetation in the tube was a spray of
-bladderwort. On examining the tube, after some days, I failed to find
-the larva. The reason was evident on removing the cork, a small part
-of which had been gnawed away to procure material for the repair of
-the larval case, which was affixed to the under side. The larva was
-dead and too much decayed to be put into pickle, a circumstance I much
-regret, as I should like to have preserved the larva in such a strange
-dwelling. As it is, I have only been able to keep the house without its
-tenant.</p>
-
-<p>Pondweed is the usual home of the larva of the Brown China Mark, and
-from the leaves of this plant the first larval case is generally
-fashioned. This was the species upon which Réaumur made his interesting
-observations, most of which have been confirmed by succeeding
-observers. In well-grown larvae the contrivance by which the animal
-is protected from contact with the water in which it lives should be
-noted, as it may be easily, with the hand lens. The skin is thickly set
-with tiny protuberances between which the water cannot penetrate, the
-surface film stretching from tip to tip of these prominences, just as
-it does over the hairs that cover the body of a water-spider.</p>
-
-<p>De Geer<a id="FNanchor_64" href="#Footnote_64" class="fnanchor">[64]</a> describes an aquatic larva of one of the China Marks
-(<i>Paraponyx stratiotata</i>), which has its breathing apparatus
-fashioned on a similar plan to that of Limnobia, though there is some<span class="pagenum" id="Page_173">[173]</span>
-difference in the details. He found his specimens on the leaves of the
-Water Soldier, and his interesting account recalls the fact to memory
-that this remarkable plant was at one time called the Marsh Aloe&mdash;an
-exceedingly appropriate name.</p>
-
-<p>He describes the filaments on the body of the larva, and concluded
-that they were probably breathing-organs, because of the dark-coloured
-vessels within them. These he traced, as we will presently do, to their
-union in the stem of the gill, and thence to the air-vessels running
-down each side of the body of the larva. He fed them on leaves of the
-Water Soldier, and kept them through the winter. In the following June
-he found them preparing to undergo their transformation into the pupal
-stage, and at the end of the month the moths came out. He was gratified
-by seeing the congress of these insects. The females deposited their
-eggs on the floating vegetation and on the sides of his aquarium, a
-little below the surface of the water, and in about eight days the
-young larvae were seen.</p>
-
-  <div class="figcenter" id="i_173" style="width: 350px">
-     <img
-    class="p2"
-    src="images/i_173.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 82</span>.&mdash;Larva of <i>Paraponyx stratiotata</i>
-(enlarged).</p>
-  </div>
-
-<p>These larvae must be very abundant, though they do not seem to be often
-taken by collectors. In describing an allied (American) species, which
-is found on Vallisneria and pondweed, Mr. Hart<span class="pagenum" id="Page_174">[174]</span> says<a id="FNanchor_65" href="#Footnote_65" class="fnanchor">[65]</a>, ‘They feed
-at first exposed on the leaf, but later two or even three leaves are
-loosely webbed together, face to face, by each larva, between which it
-remains concealed while feeding. They are, therefore, hard to discover
-unless their hiding-places are broken up by seining, or the like, when
-the larvae may be seen swimming about.’ This is, no doubt, the reason
-why these larvae are not more often taken. Anything like a seine net is
-of course out of the question for us; but masses of vegetation may be
-readily broken up by vigorously working the bottle and net backwards
-and forwards amongst them. Specimens I have seen were taken among
-duckweed; and Mr. Hart mentions one instance of part of the larval case
-being constructed of ivy-leaved duckweed, ‘which was abundant there at
-that time.’</p>
-
-<p>Now let us bring our lens to bear, so that we may make out the external
-structure, and recognize the similarity of the breathing-organs of this
-Moth-larva to those of the Crane-fly larva already treated of (p. 168).</p>
-
-<p>In order to make out the scheme of the gills, which is somewhat
-complicated, one should first of all distinguish the spiracles,
-remembering that they are not functional. And it is best to begin with
-those on the middle segments of the body. They may be detected as
-little dark spots, sometimes enclosed in a ring. The head, the first
-segment of the thorax, and the last segment of the body, bear no gills;
-the second segment of the thorax has but two pairs on each side; and
-there is but a single gill on each side of the ninth<span class="pagenum" id="Page_175">[175]</span> segment of the
-body. On the other (nine) body-segments there are the full number
-of five gills on each side, arranged two above, and three below the
-spiracle. The upper pair are called supra-stigmals, or gills which lie
-<i>above</i> the spiracles; the lower pair are called infra-stigmals,
-or gills which lie <i>below</i> the spiracles; and the single one, the
-lowest, is known as the pedal or foot gill. These technicalities need
-not give us any trouble here, in our examination of the larva; nor do
-they present any real difficulty. But it is worth while to master the
-arrangement as soon as we get hold of one of these larvae, and then we
-shall be able to take up and understand technical descriptions of this
-aquatic caterpillar and its allies, in so far, at least, as they refer
-to the breathing apparatus.</p>
-
-<p>The gills differ in their character: some few are simple, while most of
-them are more or less branched. In Limnobia the branching of the gills
-is into a simple fork; in Paraponyx this kind of division also occurs,
-and in others most of the gill branches are also given off from the
-main stem below one of the branches of the fork.</p>
-
-<p>In Fig. 84 we have a representation of one of these branched gills.
-It will not be difficult for us to make out the details as there
-shown. But the vessels that run down into the filaments, constituting
-them breathing-organs, are smaller than those of Limnobia, and will
-consequently require a little more care and patience before we can
-distinguish them.</p>
-
-  <div class="figcenter" id="i_175" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_175.jpg"
-     alt="" />
-     <p class="p0 sm"><span class="smcap">Fig. 83.</span>&mdash;Diagram of segment of Paraponyx, showing
-arrangements of tracheal gills.</p>
-  </div>
-
-  <div class="figcenter" id="i_176" style="width: 294px">
-     <img
-    class="p2"
-    src="images/i_176.jpg"
-     alt="" />
-     <p class="p0 sm"><span class="smcap">Fig. 84.</span>&mdash;Gill of Paraponyx larva. <i>a</i>, <i>b</i>,
-stem; <i>c</i>, <i>d</i>, <i>e</i>, <i>f</i>, branches;
-<i>g</i>, attachment of the air-vessel of the gill to the main
-tracheae of the body. (After De Geer.)</p>
-  </div>
-
-<p>One would think that, with such an array of<span class="pagenum" id="Page_176">[176]</span> gills, this larva ought
-to be in good case for its air-supply. It may, perhaps, be doubted
-whether this is so. At any rate, the creature adopts the same plan as
-the larva of Chironomus, which has no gills at all, for driving away
-from its case water that has parted with its oxygen. Water charged with
-oxygen pours into the case, and so the air-supply is renewed. This plan
-is nothing more than keeping the fore-part of the body in undulating
-motion, the tail in both the larvae serving as a point of attachment.
-One or two that I have kept made their cases against the side of the
-bottle, and so afforded an excellent opportunity of seeing them in this
-motion. The Tanypus larva does the same thing. Against the side of one
-of my small aquaria a Tanypus larva and a Chironomus<span class="pagenum" id="Page_177">[177]</span> larva have both
-made tubes; and as I look up from writing these lines I can see them
-both hard at this work.</p>
-
-<p>The larva of the Alder-fly (<i>Si´alis luta´rius</i>) is also furnished
-with tracheal gills, seven on each side. So little is known of the
-life-histories of common insects that it may be profitable to introduce
-the account of an observer who watched the deposition of the eggs and
-the emergence of the young larvae:</p>
-
-<p>‘On April 25 I found, on the rushes round the margin of a small pond,
-a great many patches of eggs, and shortly after observed many of the
-<i>Sialis lutarius</i> depositing them.</p>
-
-<p>‘They form large patches of from two to three inches in length,
-generally encircling the whole rush near the top, but sometimes
-deposited on one side only, and extended to about a line in breadth.</p>
-
-<p>‘I counted 100 in a square line, so that each batch may be fairly
-considered to contain from 2,000 to 3,000 eggs; the greater portion of
-which must consequently perish either in the egg or larva state; as,
-common as the insect is, and widely distributed throughout the country,
-we should be perfectly overwhelmed with the swarms of the perfect
-insect if such were permitted, when it is considered that round this
-one small pond there could not have been less than 100 patches of them.</p>
-
-<p>‘The eggs are of a very singular form, and placed in a slanting
-position.</p>
-
-<p>‘The females, while depositing them, appeared perfectly motionless on
-the rush, and varied considerably in size, being from five lines to
-nearly double that in length. Some parts of the patches of eggs are of
-a much lighter colour than the rest.</p>
-
-<p><span class="pagenum" id="Page_178">[178]</span></p>
-
-<p>‘On May 3 I found many of the eggs hatching, the little larvae tumbling
-about in great numbers, with their bodies erected like [the larvae of]
-the <i>Staphylinidae</i>.</p>
-
-<p>‘On putting them into water they swam about with the greatest activity,
-wriggling and undulating their bodies about much like a serpent or the
-tadpoles, and working their legs at the same time<a id="FNanchor_66" href="#Footnote_66" class="fnanchor">[66]</a>.’</p>
-
-<p>The author draws attention to the disproportionately large head of the
-larvae, which, however, he did not describe, as he had ‘brought some of
-them alive, and some eggs for exhibition.’</p>
-
-<p>Sialis larvae occur in most ponds with muddy bottoms. They may be taken
-by scooping up some of the mud in a long-handled spoon&mdash;a most useful
-instrument for the collector&mdash;and washing it, or by throwing in the
-drag, and bringing to land a mass of water-weed, roots and all. A few
-may generally be detected near the roots. They may be picked up with a
-small pair of forceps, or with a brush, and dropped into a bottle; or,
-better still, into separate tubes; for they are fierce and voracious,
-and, failing other food, by no means indisposed to prey on each other.</p>
-
-<p>Their general appearance, and especially their powerful mandibles, give
-them some resemblance to the larvae of a water beetle, for which a
-celebrated naturalist not unnaturally took them, when he began to study
-them. And this would seem to be the opinion of some mounters, for I
-have a slide of the mouth parts of this larvae, labelled ‘Mouth parts
-of the larvae of a water beetle.’ It was not till I had broken up a
-good many Sialis larvae that I found out what the slide really was.</p>
-
-<p><span class="pagenum" id="Page_179">[179]</span></p>
-
-<p>These larvae may be kept alive in small bottles of water, if they
-are supplied with food. They will eat Chironomus larvae and those of
-Tanypus. Professor Miall has found that they will eat caddis-worms and
-May-fly larvae. Probably, no small aquatic creatures that they can
-overcome are safe from them.</p>
-
-<p>A larva that is full-fed, and ready to change to become a pupa, will
-measure about an inch in length or a little more (Fig. 85). The general
-colour is brownish, with dark markings. The legs are powerful, and our
-lens will show us that they end in two strong curved claws. From each
-of the first seven segments of the abdomen are given off a pair of
-jointed tracheal gills or breathing-organs, which are directed upwards
-and backwards when the larva is at rest&mdash;a rare occurrence&mdash;but which
-wave to and fro in the water when the creature is swimming.</p>
-
-<p>From this fact has arisen the statement found in most books that the
-larva uses these gills not only for respiration, but for locomotion.
-Professor Miall has come to a contrary conclusion, and, as he has
-kindly informed me, is confirmed in his opinion by the weakness of the
-muscles.</p>
-
-  <div class="figcenter" id="i_179" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_179.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 85.</span>&mdash;Larva of Sialis (enlarged).</p>
-  </div>
-
-<p>It will be well to make repeated observations till we are satisfied
-on the subject. When these larvae are kept, the conditions necessary
-to provide them with food and to keep the water aërated by means of
-growing vegetation are unfavourable to close observation. It will,
-therefore, be necessary to remove one or more of these<span class="pagenum" id="Page_180">[180]</span> larvae to a
-bottle in which there is nothing but pure water.</p>
-
-<p>The work is now rendered much easier. There is nothing to obstruct. As
-soon as the larvae reach the bottom they will walk round and round,
-giving us a good opportunity of watching them. In swimming&mdash;which may
-be backwards as well as forwards&mdash;the abdomen is waved from side to
-side. To see the backward motion one need only put a dipping-tube or a
-pencil, or the like, in front of the larva, so as to bar its progress.
-The creature will retreat a step or two, and then, with a flourish of
-the abdomen, dart back through the water. The larva will sometimes wave
-the abdomen up and down, just as one may see a Chironomus larva do when
-it has affixed its dwelling to the side of the glass, and this motion
-probably assists the process of respiration.</p>
-
-<p>When the larvae have been watched under the conditions above described,
-I have never been able to detect independent motion of the gills. But
-it is better that every one should observe for himself, and draw his
-own conclusions from what he sees.</p>
-
-<p>Now let us examine a specimen more closely with the lens, or under the
-dissecting microscope. The mouth parts may be broken up separately, or
-a little careful manipulation will enable us to see the chief features
-without injuring the specimen. The head is strong and massive, and
-the group of ocelli, or simple eyes, may be clearly made out. The
-antennae bear a small pencil of hairs, no doubt sensory in function,
-at the extremity, but careful management of the light will be required
-to distinguish them. The mandibles are extremely business-like
-instruments, and each bears two strong<span class="pagenum" id="Page_181">[181]</span> teeth on the inner side. Next
-come the maxillae, with their palps, each of which has an appendage,
-while each maxilla carries three strong spines. The labium, with its
-palps, and the mentum, with its saw-like notchings, may be plainly seen.</p>
-
-<p>The three segments of the thorax offer no difficulty. The legs are
-worth more than a cursory examination from their apparatus of spines
-and double fringe of hairs. Nine body-segments succeed to the thorax,
-and behind these is a long tail-like organ, which some authors consider
-represents a tenth segment.</p>
-
-  <div class="figcenter" id="i_181a" style="width: 350px">
-     <img
-    class="p2"
-    src="images/i_181a.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 86.</span>&mdash;Diagram of Sialis larva, showing arrangement
-of gills (represented by vertical lines). <i>h</i>, head;
-<i>t</i>, thorax; 1–9, segments of abdomen.</p>
-  </div>
-
-<p>The gills are seven on each side, and are given off from the spaces
-in front of the first seven segments of the abdomen. Each gill is
-five-jointed&mdash;an unusual arrangement, for the gills of the larvae of
-Limnobia and Gyrinus are without joints. With the half-inch Leitz the
-branching tracheal tube in the gill may be seen, as well as the double
-fringe of hairs and the long hairs at the extremity. The tail-like
-organ, though without joints, bears a close resemblance to the gills.
-It has two tracheal tubes running through it, and it is fringed on both
-sides with hair. Indeed, Professor Miall, F.R.S., compares it to ‘two
-ordinary tracheal gills completely fused together.’ The first glance
-will convince the observer that the comparison is just.</p>
-
-  <div class="figcenter" id="i_181b" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_181b.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 87.</span>&mdash;Pupa of Sialis.</p>
-  </div>
-
-<p><span class="pagenum" id="Page_182">[182]</span></p>
-
-<p>The pupa (Fig. 87) need not detain us, for the larva undergoes its
-transformation in the ground, not in the water, where it could be
-watched. But it is interesting to notice that the legs and wings are
-enclosed in separate cases, and that the segments of the abdomen bear
-spines. These spines are extremely serviceable to the pupa when making
-its way out of its cell to emerge as a perfect insect, which is well
-known, especially to fishermen, as the Alder-fly. It may be found near
-streams, and rarely uses its wings.</p>
-
-<p><i>Ptychoptera paludosa</i> is a small Crane-fly, with an aquatic larva
-which will repay observation. It is one of the group generally called
-‘rat-tailed maggots,’ from the peculiar character of the breathing
-apparatus, which consists of a retractile tube at the end of the
-abdomen. It is, I believe, better known to some dealers than the larva
-of the Drone-fly, the rat-tailed maggot of Réaumur. A few months ago I
-wanted some Drone-fly larvae, and asked a dealer to supply me. When the
-larvae arrived and were turned out for examination, they proved to be
-Ptychoptera larvae&mdash;which I did not want. I naturally wrote to point
-out the mistake; and was told, in reply, that the larvae sent were the
-only ‘rat-tails’ known to my correspondent.</p>
-
-<p>This larva is a mud-dweller, and is best captured by scooping up
-surface mud near the banks of pools and ditches, just where the water
-shallows on to the shore. This should be washed in a small dish or
-saucer, so as to carry away the mud and leave the larvae wriggling
-on the bottom. They may be picked up with a brush and dropped into a
-bottle for transport home.</p>
-
-<p>There is not the slightest difficulty about keeping them for
-observation. A bottle of the capacity of<span class="pagenum" id="Page_183">[183]</span> six or eight fluid ounces
-will make a good aquarium for a dozen or even twenty. The bottom should
-be covered to the depth of about an inch with mud fairly rich in
-organic matter. My own plan has been to use the accumulation from the
-bottom of a large aquarium. In this the larvae will bury the body, and
-feed, the tail protruding and thrust up to the surface of the water, of
-which there should be about two inches above the mud.</p>
-
-<p>This is a liberal allowance of space. A couple of these larvae lived
-with me for some months in a glass capsule two inches in diameter and
-three-quarters of an inch in height. The mud at the bottom and the
-water covering it together measured about half an inch. Both pupated,
-and in due time from the pupa cases a perfect insect came out.</p>
-
-<p>But that larvae may pupate, they require to be well fed. How shall
-we know when the bulk of the nourishment has been extracted from the
-mud? From the castings of the larvae; and these, though of a different
-shape, are as easy to be distinguished as the castings of the earthworm
-in the garden or those of the lobworm on the seashore. All the mud that
-passes through the bodies of the larvae is discharged in the form of
-tiny hard, cylindrical pellets; and when the mass consists of these
-pellets it should be changed, or the larvae will go short of food. They
-will, however, support long fasts.</p>
-
-<p>From Fig. 88 we may get a good idea of the appearance of the larvae
-when kept in confinement. The figures are rather less than natural
-size, and all the attitudes were sketched from life. One is seen
-extended on the bottom; two are partially buried in the mud, with the
-breathing-tube protruding. The larva on the mud, and bent into<span class="pagenum" id="Page_184">[184]</span> curves,
-is just about to rise to the surface; others are shown in the act of
-rising, while one has its breathing-tube raised above the surface, and
-another is attached by the breathing-tube to the side of the glass
-vessel. The larva with the star-like process at the end of the tail is
-that of Odontomyia, a large bee-like fly.</p>
-
-  <div class="figcenter" id="i_184" style="width: 400px">
-     <img
-    class="p2"
-    src="images/i_184.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 88.</span>&mdash;Larvae of <i>Ptychoptera paludosa</i>
-(from life).</p>
-  </div>
-
-<p>A larva of good size, like that of Ptychoptera, is especially easy to
-examine; and by reason of its transparency the tracheal tubes may be
-clearly traced. The under surface of the larva should be first looked
-at, and its adaptation for existence in the mud of a pond-bottom will
-be evident. The creature is legless, but possesses three pairs of
-false legs armed with dark-coloured hooks, and each body-segment bears
-a circle of stiff hairs, which<span class="pagenum" id="Page_185">[185]</span> enable the larva to travel through
-the mud, in the same way that the earthworm moves through the soil.
-Moreover, the segments between these circles are pretty thickly set
-with hairs.</p>
-
-<p>The tracheal tubes run down on each side of the body, not in a direct
-line, for there is a most ingenious arrangement by which contraction
-and expansion of the larva, and the protrusion and retraction of
-the tail, are provided for. One can easily discern that in most of
-the segments the tubes are large, and that these large portions are
-connected by smaller tubes, whence others are given off into the body.
-These connecting-tubes are loop-like when the larva is of the normal
-length, but are straightened out, thus adding to their length, when the
-larva is extended.</p>
-
-<p>The opening and closing of these loops may be observed at leisure if
-a larva be put in a long excavated slip, with some water, and then
-covered with a plain glass slip. The two slips, fastened together with
-small elastic bands, should then be laid on the stage of the dissecting
-microscope for examination; or they may be held in the hands, and the
-movements of the larva watched with the hand lens.</p>
-
-<p>In the posterior segments of the body the tracheal tubes run side by
-side, while in the tail itself they are, so to speak, intertwined. When
-the tip of the tail pierces the surface-film a fresh supply of air is
-taken in.</p>
-
-<p>At the base of the extensile portion are two processes which diverge,
-one on each side, at an angle of 45 degrees. These, according to a
-German observer, are tracheal gills, and they are absorbed just before
-the larva enters the pupal condition.</p>
-
-<p>Réaumur found these larvae plentifully in the<span class="pagenum" id="Page_186">[186]</span> Bois de Boulogne, and
-gives a figure<a id="FNanchor_67" href="#Footnote_67" class="fnanchor">[67]</a>. He was not, however, successful in rearing the fly.
-Lyonnet not only took the larvae and kept them in an aquarium, but
-watched their change into the pupal condition, and saw them emerge as
-perfect insects. An abstract of this description will probably be of
-interest.</p>
-
-  <div class="figcenter" id="i_186" style="width: 200px">
-     <img
-    class="p2"
-    src="images/i_186.jpg"
-     alt="" />
-     <p class="p0 sm"><span class="smcap">Fig. 89.</span>&mdash;<i>A.</i> Ptychoptera larva (enlarged).
-<i>B.</i> Tail, showing air-vessels (still more enlarged).
-(After Lyonnet.)</p>
-  </div>
-
-<p>He tells us that the larvae showed signs of changing into pupae in
-June. The change was made without the larvae leaving the water, and
-they underwent all their transformations in less than a fortnight.
-At the approach of the change the larvae became whiter in colour,
-but less transparent. Then they cast their skin, leaving therein the
-air-vessels, or rather their external covering. After this last moult
-was over, he was surprised to find that the tube which formed the tail
-of the larva, and by which it took in a supply of air, though it serves
-the same purpose in the pupa, is<span class="pagenum" id="Page_187">[187]</span> attached to the thorax, near the top
-of the head<a id="FNanchor_68" href="#Footnote_68" class="fnanchor">[68]</a>. Lyonnet appears to have overlooked the fact that there
-was a second and shorter tube given off from the thorax, which most
-observers consider to be functionless (Fig. 90).</p>
-
-  <div class="figcenter" id="i_187" style="width: 300px">
-     <img
-    class="p2"
-    src="images/i_187.jpg"
-     alt="" />
-     <p class="p0 sm center"><span class="smcap">Fig. 90.</span>&mdash;Pupa of Ptychoptera. (After Lyonnet.)</p>
-  </div>
-
-<p>Strange as is the larva, the pupa is stranger still, and seems even
-better adapted for existence in the mud. The hinder part of each
-segment of the abdomen is thickened and studded with chitinous
-projections. This thickening is more marked, and of greater extent in
-each succeeding segment, reaching its greatest development in the last
-segment, which is armed with hooks. The body part of each segment bears
-rows of smaller spines, so that this pupa should have little or no
-difficulty in moving through pretty thick mud.</p>
-
-<p>Several of these Crane-flies have passed through<span class="pagenum" id="Page_188">[188]</span> all their stages with
-me, and in nearly every case the transformation from pupa to perfect
-insect was made in water&mdash;in a tube three inches long, with a diameter
-of about an inch. The larvae were taken about the middle of September.
-My notes show that the first pupated on November 17, and the first fly
-came out on November 25.</p>
-
-<p>The long breathing-tube of the pupa was several times purposely
-displaced from its position on the surface. The creature was evidently
-incommoded, and twisted itself into strong curves; the head was thrown
-from side to side till part of the breathing-tube was raised above the
-surface and adhered to the side of the glass tube. Nor did the efforts
-cease till a considerable portion of the tube was in free communication
-with the air. This would seem to show that the air-supply is taken
-through the bladders which appear at irregular intervals in the
-breathing-tube, and not at the tip, where the keenest observers have
-failed to find an opening.</p>
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_189">[189]</span></p>
-
-<h2>INDEX</h2>
-</div>
-
-<ul>
-  <li>Acridiidae,
-    <a href="#Page_80">80</a>.</li>
-
-  <li>Alder-fly, larva of,
-    <a href="#Page_177">177</a>;</li>
-  <li class="i1">pupa of,
-    <a href="#Page_182">182</a>.</li>
-
-  <li>American Cockroach,
-    <a href="#Page_74">74</a>.</li>
-
-  <li>Amphipods,
-    <a href="#Page_141">141</a>;</li>
-  <li class="i1">Rev. T. R. R. Stebbing on,
-    <a href="#Page_141">141</a>.</li>
-
-  <li>Aquaria, description of,
-    <a href="#Page_20">20</a>.</li>
-
-  <li>Arachnoidea,
-    <a href="#Page_96">96</a>.</li>
-
-  <li><i>Argyroneta aquatica</i>,
-    <a href="#Page_108">108</a>;</li>
-  <li class="i1">De Geer on,
-    <a href="#Page_109">109</a>;</li>
-  <li class="i1">nest of,
-    <a href="#Page_110">110</a>.</li>
-
-  <li>Arthropods,
-    <a href="#Page_27">27</a>;</li>
-  <li class="i1">divisions of,
-    <a href="#Page_28">28</a>;</li>
-  <li class="i1">description of,
-    <a href="#Page_29">29</a>.</li>
-
-  <li>Ascidians, Darwin on,
-    <a href="#Page_13">13</a>.</li>
-
-  <li><i>Asellus aquaticus</i>, description of,
-    <a href="#Page_153">153</a>.</li>
-
-  <li>Assassin Worm,
-    <a href="#Page_158">158</a>.</li>
-
-  <li>Aurivillius, Dr., on Crabs,
-    <a href="#Page_150">150</a>.</li>
-</ul>
-
-<ul>
-  <li>Bate and Westwood on Gammarus,
-    <a href="#Page_147">147</a>;</li>
-  <li class="i1">on Talitrus,
-    <a href="#Page_151">151</a>.</li>
-
-  <li>Bateman, Rev. G. C., on Hydrophilus,
-    <a href="#Page_50">50</a>;</li>
-  <li class="i1">on Nepa,
-    <a href="#Page_91">91</a>;</li>
-  <li class="i1">on China Marks,
-    <a href="#Page_171">171</a>.</li>
-
-  <li>Beakers,
-    <a href="#Page_21">21</a>.</li>
-
-  <li>Beetle Mite,
-    <a href="#Page_119">119</a>.</li>
-
-  <li>Belt on Blatta,
-    <a href="#Page_67">67</a>.</li>
-
-  <li>Black Beetle,
-    <a href="#Page_63">63</a>.</li>
-
-  <li>Black-bobs,
-    <a href="#Page_64">64</a>.</li>
-
-  <li>Blackwall on Spiders,
-    <a href="#Page_101">101</a>,
-    <a href="#Page_102">102</a>.</li>
-
-  <li><i>Blatta orientalis</i>, description of,
-    <a href="#Page_63">63</a>,
-    <a href="#Page_66">66</a>;</li>
-  <li class="i1">Gilbert White on,
-    <a href="#Page_64">64</a>;</li>
-  <li class="i1">Dr. Sharp on,
-    <a href="#Page_65">65</a>;</li>
-  <li class="i1">Belt on,
-    <a href="#Page_67">67</a>;</li>
-  <li class="i1">Sir J. Lubbock on,
-    <a href="#Page_68">68</a>;</li>
-  <li class="i1">anatomy of,
-    <a href="#Page_68">68</a>;</li>
-  <li class="i1">breathing of,
-    <a href="#Page_70">70</a>;</li>
-  <li class="i1">Swammerdam on,
-    <a href="#Page_74">74</a>;</li>
-  <li class="i1">Professor Plateau on,
-    <a href="#Page_74">74</a>.</li>
-
-  <li>Book Scorpions,
-    <a href="#Page_96">96</a>.</li>
-
-  <li><i>Brachelytra</i>,
-    <a href="#Page_59">59</a>.</li>
-
-  <li>Broad-clawed Porcelain Crab,
-    <a href="#Page_139">139</a>.</li>
-
-  <li>Brown China Mark,
-    <a href="#Page_172">172</a>.</li>
-
-  <li>Brushes,
-    <a href="#Page_23">23</a>.</li>
-
-  <li>Bugs,
-    <a href="#Page_86">86</a>.</li>
-
-  <li>Burgess, Mr., on larva of Dytiscus,
-    <a href="#Page_160">160</a>.</li>
-
-  <li>Butler, Dr., on Spiders,
-    <a href="#Page_100">100</a>.</li>
-
-  <li>Butler, Mr. E. A., on Forficula,
-    <a href="#Page_79">79</a>.</li>
-</ul>
-
-<ul>
-  <li>Capsules,
-    <a href="#Page_21">21</a>.</li>
-
-  <li><i>Carcinus maenas</i>, description of,
-    <a href="#Page_136">136</a>.</li>
-
-  <li>Centipedes,
-    <a href="#Page_122">122</a>;</li>
-  <li class="i1">marine,
-    <a href="#Page_125">125</a>.</li>
-
-  <li>Cerci,
-    <a href="#Page_47">47</a>.</li>
-
-  <li>Chelate, meaning of word,
-    <a href="#Footnote_45">132 <i>n.</i></a></li>
-
-  <li>China Marks,
-    <a href="#Page_171">171</a>;</li>
-  <li class="i1">Rev. G. C. Bateman on,
-    <a href="#Page_171">171</a>;</li>
-  <li class="i1">De Geer on,
-    <a href="#Page_172">172</a>.</li>
-
-  <li>Cockroach,
-    <a href="#Page_63">63</a>.</li>
-
-  <li>Cocktail Beetle,
-    <a href="#Page_57">57</a>.</li>
-
-  <li>Coleoptera,
-    <a href="#Page_32">32</a>.</li>
-
-  <li>Collecting, method of,
-    <a href="#Page_25">25</a>.</li>
-
-  <li>Corixa,
-    <a href="#Page_94">94</a>;</li>
-  <li class="i1">Graber on,
-    <a href="#Page_95">95</a>;</li>
-  <li class="i1">Sir J. Lubbock on,
-    <a href="#Page_95">95</a>.</li>
-
-  <li>Crab, Shore,
-    <a href="#Page_136">136</a>;</li>
-  <li class="i1">Porcelain,
-    <a href="#Page_139">139</a>.</li>
-
-  <li>Crane-fly,
-    <a href="#Page_165">165</a>.</li>
-
-  <li>Crustacea,
-    <a href="#Page_128">128</a>.</li>
-</ul>
-
-<ul>
-  <li>Daddy-longlegs,
-    <a href="#Page_103">103</a>.</li>
-
-  <li>Dallas on Ocypus,
-    <a href="#Page_61">61</a>.<span class="pagenum" id="Page_190">[190]</span></li>
-
-  <li>Darwin on microscopes,
-    <a href="#Page_12">12</a>;</li>
-  <li class="i1">on Ascidians,
-    <a href="#Page_13">13</a>.</li>
-
-  <li>Devil’s Coach Horse,
-    <a href="#Page_57">57</a>.</li>
-
-  <li>Dipping-tubes,
-    <a href="#Page_23">23</a>.</li>
-
-  <li>Dissecting microscope,
-    <a href="#Page_18">18</a>.</li>
-
-  <li>Dissection, mode of,
-    <a href="#Page_37">37</a>.</li>
-
-  <li>Diving Spiders,
-    <a href="#Page_108">108</a>.</li>
-
-  <li>Dugès on Water Mites,
-    <a href="#Page_117">117</a>.</li>
-
-  <li>Dung Beetle,
-    <a href="#Page_119">119</a>.</li>
-
-  <li><i>Dytiscus marginalis</i>,
-    <a href="#Page_31">31</a>;</li>
-  <li class="i1">etymology of,
-    <a href="#Footnote_7">33 <i>n.</i></a>;</li>
-  <li class="i1">breaking of shells by,
-    <a href="#Page_33">33</a>;</li>
-  <li class="i1">Sowerby on,
-    <a href="#Page_34">34</a>;</li>
-  <li class="i1">description of,
-    <a href="#Page_35">35</a>;</li>
-  <li class="i1">food of,
-    <a href="#Page_36">36</a>;</li>
-  <li class="i1">anatomy of,
-    <a href="#Page_37">37</a>;</li>
-  <li class="i1">habits of,
-    <a href="#Page_41">41</a>;</li>
-  <li class="i1">Kirby on,
-    <a href="#Page_41">41</a>;</li>
-  <li class="i1">Sir J. Lubbock on,
-    <a href="#Page_42">42</a>;</li>
-  <li class="i1">Professors Lowne and Miall on,
-    <a href="#Page_45">45</a>;</li>
-  <li class="i1">Dr. Sharp on,
-    <a href="#Page_47">47</a>;</li>
-  <li class="i1">abdomen of,
-    <a href="#Page_47">47</a>;</li>
-  <li class="i1">breathing of,
-    <a href="#Page_48">48</a>;</li>
-  <li class="i1">larva of,
-    <a href="#Page_157">157</a>;</li>
-  <li class="i1">Swammerdam on,
-    <a href="#Page_158">158</a>,
-    <a href="#Page_159">159</a>;</li>
-  <li class="i1">Mr. Burgess on,
-    <a href="#Page_160">160</a>.</li>
-</ul>
-
-<ul>
-  <li>Earwig,
-    <a href="#Page_75">75</a>.</li>
-
-  <li>Edriophthalma,
-    <a href="#Page_129">129</a>.</li>
-
-  <li>Elytra,
-    <a href="#Page_41">41</a>.</li>
-
-  <li><i>Epeira diadema</i>, description of,
-    <a href="#Page_98">98</a>;</li>
-  <li class="i1">web of,
-    <a href="#Page_98">98</a>;</li>
-  <li class="i1">J. A. Thomson on,
-    <a href="#Page_100">100</a>;</li>
-  <li class="i1">Dr. Butler on,
-    <a href="#Page_100">100</a>;</li>
-  <li class="i1">Blackwall on,
-    <a href="#Page_101">101</a>,
-    <a href="#Page_102">102</a>;</li>
-  <li class="i1">mode of taking its prey,
-    <a href="#Page_102">102</a>;</li>
-  <li class="i1">Hudson on,
-    <a href="#Page_103">103</a>;</li>
-  <li class="i1">feet of,
-    <a href="#Page_104">104</a>;</li>
-  <li class="i1">spinnerets of,
-    <a href="#Page_105">105</a>.</li>
-
-  <li>Evans, W., on Sialis,
-    <a href="#Page_177">177</a>.</li>
-</ul>
-
-<ul>
-  <li><i>Field</i>, the, quoted,
-    <a href="#Page_33">33</a>,
-    <a href="#Page_35">35</a>.</li>
-
-  <li>Forceps,
-    <a href="#Page_22">22</a>.</li>
-
-  <li><i>Forficula auricularia</i>,
-    <a href="#Page_75">75</a>;</li>
-  <li class="i1">Kirby and Spence on,
-    <a href="#Page_76">76</a>;</li>
-  <li class="i1">De Geer on,
-    <a href="#Page_76">76</a>;</li>
-  <li class="i1">young of,
-    <a href="#Page_76">76</a>;</li>
-  <li class="i1">forceps of,
-    <a href="#Page_77">77</a>;</li>
-  <li class="i1">anatomy of,
-    <a href="#Page_77">77</a>;</li>
-  <li class="i1">Butler on,
-    <a href="#Page_79">79</a>;</li>
-  <li class="i1">Dr. Sharp on,
-    <a href="#Page_79">79</a>.</li>
-
-  <li>Formalin,
-    <a href="#Page_24">24</a>.</li>
-
-  <li>Forty-legs,
-    <a href="#Page_122">122</a>.</li>
-
-  <li>Fresh-water Shrimp,
-    <a href="#Page_142">142</a>.</li>
-</ul>
-
-<ul>
-  <li><i>Gamasus coleoptratorum</i>,
-    <a href="#Page_119">119</a>.</li>
-
-  <li><i>Gammarus marinus</i>,
-    <a href="#Page_146">146</a>;</li>
-  <li class="i1">Dr. J. Salter on,
-    <a href="#Page_147">147</a>.</li>
-
-  <li><i>Gammarus pulex</i>,
-    <a href="#Page_142">142</a>;</li>
-  <li class="i1">anatomy of,
-    <a href="#Page_144">144</a>.</li>
-
-  <li>Geer, De, on Forficula,
-    <a href="#Page_76">76</a>;</li>
-  <li class="i1">on Locusta,
-    <a href="#Page_80">80</a>;</li>
-  <li class="i1">on Water Mites,
-    <a href="#Page_116">116</a>;</li>
-  <li class="i1">on Beetle Mites,
-    <a href="#Page_120">120</a>;</li>
-  <li class="i1">on Lithobius,
-    <a href="#Page_123">123</a>;</li>
-  <li class="i1">on Julus,
-    <a href="#Page_126">126</a>;</li>
-  <li class="i1">on larva of Limnobia,
-    <a href="#Page_167">167</a>;</li>
-  <li class="i1">on Paraponyx,
-    <a href="#Page_172">172</a>.</li>
-
-  <li>Geophilus,
-    <a href="#Page_124">124</a>.</li>
-
-  <li><i>Geophilus crassipes</i>,
-    <a href="#Page_125">125</a>;</li>
-  <li class="i1">Mr. Pocock on,
-    <a href="#Page_125">125</a>.</li>
-
-  <li>Glass block,
-    <a href="#Page_22">22</a>.</li>
-
-  <li>Glass box,
-    <a href="#Page_22">22</a>.</li>
-
-  <li>Glass slips,
-    <a href="#Page_22">22</a>.</li>
-
-  <li>Gosse on Prawns,
-    <a href="#Page_133">133</a>.</li>
-
-  <li>Graber on Corixa,
-    <a href="#Page_95">95</a>.</li>
-
-  <li>Grasshopper, Great Green,
-    <a href="#Page_80">80</a>.</li>
-
-  <li>Great Water Beetle,
-    <a href="#Page_49">49</a>.</li>
-</ul>
-
-<ul>
-  <li>Hart, Mr., on Paraponyx,
-    <a href="#Page_173">173</a>.</li>
-
-  <li>Harvestmen,
-    <a href="#Page_96">96</a>.</li>
-
-  <li>Hemiptera,
-    <a href="#Page_86">86</a>.</li>
-
-  <li>Hill, Dr., on Nepa,
-    <a href="#Page_90">90</a>.</li>
-
-  <li>Hudson on Spiders,
-    <a href="#Page_103">103</a>.</li>
-
-  <li>Hundred-legs,
-    <a href="#Page_122">122</a>.</li>
-
-  <li>Hunting Spiders,
-    <a href="#Page_98">98</a>.</li>
-
-  <li>Hydrachna,
-    <a href="#Page_113">113</a>.</li>
-
-  <li><i>Hydrachna globula</i>,
-    <a href="#Footnote_37">118 <i>n.</i></a></li>
-
-  <li>Hydrophilus, larva of,
-    <a href="#Page_164">164</a>;</li>
-  <li class="i1">Lyonnet on,
-    <a href="#Page_164">164</a>.</li>
-
-  <li><i>Hydrophilus piceus</i>,
-    <a href="#Page_49">49</a>;</li>
-  <li class="i1">Bateman on,
-    <a href="#Page_50">50</a>;</li>
-  <li class="i1">legs of,
-    <a href="#Page_53">53</a>;</li>
-  <li class="i1">Simmermacher on,
-    <a href="#Page_53">53</a>;</li>
-  <li class="i1">breathing of,
-    <a href="#Page_54">54</a>;</li>
-  <li class="i1">cocoons of,
-    <a href="#Page_54">54</a>;</li>
-  <li class="i1">Lyonnet on,
-    <a href="#Page_54">54</a>.</li>
-
-  <li>Hymenoptera, wings of,
-    <a href="#Page_170">170</a>.</li>
-</ul>
-
-<ul>
-  <li>Idotea,
-    <a href="#Page_143">143</a>.</li>
-
-  <li><i>Idotea pelagica</i>,
-    <a href="#Page_155">155</a>.</li>
-
-  <li>Illinois State Laboratory, mode of collecting in,
-    <a href="#Page_25">25</a>.</li>
-
-  <li>‘Insects,’
-    <a href="#Page_27">27</a>;</li>
-  <li class="i1">divisions of,
-    <a href="#Page_32">32</a>.</li>
-
-  <li>Invertebrates,
-    <a href="#Page_28">28</a>.</li>
-
-  <li>Isopods,
-    <a href="#Page_152">152</a>.</li>
-</ul>
-
-<ul>
-  <li>Julus,
-    <a href="#Page_121">121</a>,
-    <a href="#Page_124">124</a>.</li>
-
-  <li><i>Julus terrestris</i>,
-    <a href="#Page_126">126</a>;</li>
-  <li class="i1">De Geer on,
-    <a href="#Page_126">126</a>;</li>
-  <li class="i1">Dr. Sharp on,
-    <a href="#Page_126">126</a>.</li>
-
-  <li>Jumping Spiders,
-    <a href="#Page_105">105</a>.<span class="pagenum" id="Page_191">[191]</span></li>
-</ul>
-
-<ul>
-  <li>Kew, Mr., on dispersal of shells,
-    <a href="#Page_130">130</a>.</li>
-
-  <li>Kirby on Dytiscus,
-    <a href="#Page_41">41</a>;</li>
-  <li class="i1">on Ocypus,
-    <a href="#Page_59">59</a>;</li>
-  <li class="i1">on Forficula,
-    <a href="#Page_76">76</a>;</li>
-  <li class="i1">on Locusta,
-    <a href="#Page_83">83</a>;</li>
-  <li class="i1">on insect noises,
-    <a href="#Page_84">84</a>;</li>
-  <li class="i1">on Salticus,
-    <a href="#Page_107">107</a>.</li>
-
-  <li>Knives,
-    <a href="#Page_24">24</a>.</li>
-</ul>
-
-<ul>
-  <li>Land Bugs,
-    <a href="#Page_86">86</a>.</li>
-
-  <li>Leaping Orthoptera,
-    <a href="#Page_79">79</a>.</li>
-
-  <li>Leitz, lenses of,
-    <a href="#Page_16">16</a>.</li>
-
-  <li>Lichtenstein on Locusta,
-    <a href="#Page_83">83</a>.</li>
-
-  <li>Limnaea broken by Dytiscus,
-    <a href="#Page_33">33</a>.</li>
-
-  <li><i>Limnobia replicata</i>, larva of,
-    <a href="#Page_165">165</a>;</li>
-  <li class="i1">De Geer on,
-    <a href="#Page_167">167</a>;</li>
-  <li class="i1">pupa of,
-    <a href="#Page_168">168</a>.</li>
-
-  <li><i>Lithobius forficatus</i>,
-    <a href="#Page_122">122</a>;</li>
-  <li class="i1">De Geer on,
-    <a href="#Page_123">123</a>;</li>
-  <li class="i1">Dr. Sharp on,
-    <a href="#Page_123">123</a>.</li>
-
-  <li><i>Locusta viridissima</i>,
-    <a href="#Page_80">80</a>;</li>
-  <li class="i1">Dr. Sharp on,
-    <a href="#Page_80">80</a>,
-    <a href="#Page_85">85</a>;</li>
-  <li class="i1">De Geer on,
-    <a href="#Page_80">80</a>,
-    <a href="#Page_83">83</a>;</li>
-  <li class="i1">Westwood on,
-    <a href="#Page_81">81</a>;</li>
-  <li class="i1">Kirby on,
-    <a href="#Page_83">83</a>;</li>
-  <li class="i1">Lichtenstein on,
-    <a href="#Page_83">83</a>;</li>
-  <li class="i1">ear of,
-    <a href="#Page_85">85</a>.</li>
-
-  <li>Locustidae,
-    <a href="#Page_80">80</a>.</li>
-
-  <li>Lowne, Professor, on Dytiscus,
-    <a href="#Page_45">45</a>.</li>
-
-  <li>Lubbock, Sir J., on Dytiscus,
-    <a href="#Page_42">42</a>;</li>
-  <li class="i1">on Blatta,
-    <a href="#Page_68">68</a>;</li>
-  <li class="i1">on Corixa,
-    <a href="#Page_95">95</a>;</li>
-  <li class="i1">on Opossum Shrimp,
-    <a href="#Page_135">135</a>.</li>
-
-  <li>Lyonnet on larva of Hydrophilus,
-    <a href="#Page_164">164</a>;</li>
-  <li class="i1">on Ptychoptera,
-    <a href="#Page_186">186</a>.</li>
-</ul>
-
-<ul>
-  <li>Magnification, power of,
-    <a href="#Footnote_2">15 <i>n.</i></a></li>
-
-  <li>Mainland, Mr. G. E., on Water Mites,
-    <a href="#Page_118">118</a>.</li>
-
-  <li>Malacostraca,
-    <a href="#Page_128">128</a>;</li>
-  <li class="i1">Rev. T. R. R. Stebbing on,
-    <a href="#Page_128">128</a>.</li>
-
-  <li>Margined Water Beetle,
-    <a href="#Page_31">31</a>.</li>
-
-  <li>Masking Crabs,
-    <a href="#Page_150">150</a>.</li>
-
-  <li><i>Melicerta janus</i>,
-    <a href="#Page_150">150</a>.</li>
-
-  <li>Miall, Professor, on Dytiscus,
-    <a href="#Page_45">45</a>;</li>
-  <li class="i1">on Sialis larvae,
-    <a href="#Page_179">179</a>,
-    <a href="#Page_181">181</a>.</li>
-
-  <li>Microscopes, use of,
-    <a href="#Page_11">11</a>;</li>
-  <li class="i1">description of,
-    <a href="#Page_15">15</a>.</li>
-
-  <li>Millepedes,
-    <a href="#Page_121">121</a>,
-    <a href="#Page_125">125</a>.</li>
-
-  <li>Mites, description of,
-    <a href="#Page_112">112</a>.</li>
-
-  <li>Model, a calico,
-    <a href="#Page_30">30</a>.</li>
-
-  <li>Myriapods,
-    <a href="#Page_96">96</a>,
-    <a href="#Page_120">120</a>.</li>
-
-  <li>Mysis,
-    <a href="#Page_135">135</a>.</li>
-</ul>
-
-<ul>
-  <li><i>Nature Notes</i> on Millepedes,
-    <a href="#Page_121">121</a>.</li>
-
-  <li>Needles,
-    <a href="#Page_23">23</a>.</li>
-
-  <li><i>Nepa cinerea</i>,
-    <a href="#Page_86">86</a>;</li>
-  <li class="i1">mode of keeping,
-    <a href="#Page_88">88</a>;</li>
-  <li class="i1">Swammerdam on,
-    <a href="#Page_89">89</a>;</li>
-  <li class="i1">Dr. Hill on,
-    <a href="#Page_90">90</a>;</li>
-  <li class="i1">Rev. G. C. Bateman on,
-    <a href="#Page_91">91</a>;</li>
-  <li class="i1">anatomy of,
-    <a href="#Page_91">91</a>.</li>
-
-  <li>Noises made by insects,
-    <a href="#Page_84">84</a>.</li>
-
-  <li><i>Notonecta glauca</i>,
-    <a href="#Page_93">93</a>.</li>
-</ul>
-
-<ul>
-  <li><i>Ocypus olens</i>,
-    <a href="#Page_57">57</a>;</li>
-  <li class="i1">Kirby on,
-    <a href="#Page_59">59</a>;</li>
-  <li class="i1">as a pet,
-    <a href="#Page_59">59</a>;</li>
-  <li class="i1">Dallas on,
-    <a href="#Page_61">61</a>;</li>
-  <li class="i1">larva of,
-    <a href="#Page_61">61</a>.</li>
-
-  <li>Opossum Shrimp,
-    <a href="#Page_135">135</a>;</li>
-  <li class="i1">Sir J. Lubbock on,
-    <a href="#Page_135">135</a>.</li>
-
-  <li><i>Orchestia littorea</i>,
-    <a href="#Page_151">151</a>.</li>
-
-  <li>Orthoptera,
-    <a href="#Page_63">63</a>.</li>
-
-  <li>Ovipositors,
-    <a href="#Page_82">82</a>.</li>
-</ul>
-
-<ul>
-  <li><i>Palaemon serratus</i>,
-    <a href="#Page_129">129</a>.</li>
-
-  <li><i>Palaemonetes varians</i>,
-    <a href="#Page_130">130</a>.</li>
-
-  <li><i>Paraponyx stratiotata</i>,
-    <a href="#Page_171">171</a>;</li>
-  <li class="i1">De Geer on,
-    <a href="#Page_172">172</a>;</li>
-  <li class="i1">Mr. Hart on,
-    <a href="#Page_173">173</a>;</li>
-  <li class="i1">anatomy of,
-    <a href="#Page_174">174</a>.</li>
-
-  <li>Peripatus,
-    <a href="#Page_30">30</a>;</li>
-  <li class="i1">Professor Sedgwick on,
-    <a href="#Page_31">31</a>.</li>
-
-  <li><i>Periplaneta americana</i>,
-    <a href="#Page_74">74</a>.</li>
-
-  <li>Pholcus,
-    <a href="#Page_103">103</a>.</li>
-
-  <li>Phylum, definition of,
-    <a href="#Page_27">27</a>.</li>
-
-  <li>Planorbis broken by Dytiscus,
-    <a href="#Page_33">33</a>.</li>
-
-  <li>Plateau, Professor, on Blatta,
-    <a href="#Page_74">74</a>.</li>
-
-  <li>Pocket lens, description of,
-    <a href="#Page_13">13</a>.</li>
-
-  <li>Pocock, Mr., on Geophilus,
-    <a href="#Page_125">125</a>.</li>
-
-  <li>Podophthalma,
-    <a href="#Page_129">129</a>.</li>
-
-  <li><i>Porcellana platycheles</i>,
-    <a href="#Page_139">139</a>.</li>
-
-  <li>Prawns,
-    <a href="#Page_129">129</a>;</li>
-  <li class="i1">Gosse on,
-    <a href="#Page_133">133</a>;</li>
-  <li class="i1">Sowerby on,
-    <a href="#Page_133">133</a>.</li>
-
-  <li>Ptychoptera, larva of,
-    <a href="#Page_182">182</a>;</li>
-  <li class="i1">pupa of,
-    <a href="#Page_187">187</a>;</li>
-  <li class="i1">Réaumur on,
-    <a href="#Page_185">185</a>;</li>
-  <li class="i1">Lyonnet on,
-    <a href="#Page_186">186</a>.</li>
-</ul>
-
-<ul>
-  <li>Quekett Microscopical Club, incident at,
-    <a href="#Page_20">20</a>.<span class="pagenum" id="Page_192">[192]</span></li>
-</ul>
-
-<ul>
-  <li>‘Rat-tails,’
-    <a href="#Page_182">182</a>.</li>
-
-  <li>Réaumur on Ptychoptera,
-    <a href="#Page_185">185</a>.</li>
-
-  <li>Robertson, Mr., on Talitrus,
-    <a href="#Page_151">151</a>.</li>
-</ul>
-
-<ul>
-  <li>Salter, Dr. J., on Gammarus,
-    <a href="#Page_147">147</a>.</li>
-
-  <li><i>Salticus scenicus</i>,
-    <a href="#Page_105">105</a>;</li>
-  <li class="i1">Kirby and Spence on,
-    <a href="#Page_107">107</a>;</li>
-  <li class="i1">foot of,
-    <a href="#Page_108">108</a>.</li>
-
-  <li>Sand-hopper,
-    <a href="#Page_151">151</a>.</li>
-
-  <li>Scorpions,
-    <a href="#Page_96">96</a>.</li>
-
-  <li>Sedgwick, Professor, on Peripatus,
-    <a href="#Page_31">31</a>.</li>
-
-  <li>Sharp, Dr., on Dytiscus,
-    <a href="#Page_47">47</a>;</li>
-  <li class="i1">on Blatta,
-    <a href="#Page_65">65</a>;</li>
-  <li class="i1">on Forficula,
-    <a href="#Page_79">79</a>;</li>
-  <li class="i1">on Locusta,
-    <a href="#Page_80">80</a>,
-    <a href="#Page_85">85</a>;</li>
-  <li class="i1">on Lithobius,
-    <a href="#Page_123">123</a>;</li>
-  <li class="i1">on Julus,
-    <a href="#Page_126">126</a>;</li>
-  <li class="i1">on wings of Hymenoptera,
-    <a href="#Page_170">170</a>.</li>
-
-  <li>Shells broken by Dytiscus,
-    <a href="#Page_33">33</a>;</li>
-  <li class="i1">Mr. Kew on dispersal of,
-    <a href="#Page_130">130</a>.</li>
-
-  <li>Shore Crab,
-    <a href="#Page_136">136</a>.</li>
-
-  <li>Shore-hopper,
-    <a href="#Page_151">151</a>.</li>
-
-  <li>Shrimp,
-    <a href="#Page_132">132</a>.</li>
-
-  <li><i>Sialis lutarius</i>, larva of,
-    <a href="#Page_177">177</a>;</li>
-  <li class="i1">W. Evans on,
-    <a href="#Page_177">177</a>;</li>
-  <li class="i1">anatomy of,
-    <a href="#Page_180">180</a>;</li>
-  <li class="i1">pupa of,
-    <a href="#Page_182">182</a>.</li>
-
-  <li>Sicarius,
-    <a href="#Page_158">158</a>.</li>
-
-  <li>Simmermacher on Hydrophilus,
-    <a href="#Page_53">53</a>.</li>
-
-  <li>Sirex,
-    <a href="#Page_82">82</a>.</li>
-
-  <li>Sowerby, G. B., on Dytiscus,
-    <a href="#Page_34">34</a>.</li>
-
-  <li>Sphaerium,
-    <a href="#Page_130">130</a>.</li>
-
-  <li>Sphaeroma,
-    <a href="#Page_155">155</a>.</li>
-
-  <li>Spiders, general description of,
-    <a href="#Page_96">96</a>;</li>
-  <li class="i1">Trap-door,
-    <a href="#Page_97">97</a>;</li>
-  <li class="i1">Hunting,
-    <a href="#Page_98">98</a>;</li>
-  <li class="i1">Garden,
-    <a href="#Page_98">98</a>;</li>
-  <li class="i1">Jumping,
-    <a href="#Page_105">105</a>;</li>
-  <li class="i1">Diving,
-    <a href="#Page_108">108</a>.</li>
-
-  <li class="hangingindent">Stebbing, Rev. T. R. R., on etymology of Dytiscus,
-    <a href="#Footnote_7">33 <i>n.</i></a>;</li>
-  <li class="i1">on Malacostraca,
-    <a href="#Page_128">128</a>;</li>
-  <li class="hangingindent1">on meaning of <i>chelate</i> and <i>sub-chelate</i>,
-    <a href="#Footnote_45">132 <i>n.</i></a>;</li>
-  <li class="i1">on Amphipods,
-    <a href="#Page_141">141</a>.</li>
-
-  <li>Stewart, Professor, incident of,
-    <a href="#Page_20">20</a>.</li>
-
-  <li>Stilopyga,
-    <a href="#Page_63">63</a>.</li>
-
-  <li>Swammerdam on Blatta,
-    <a href="#Page_74">74</a>;</li>
-  <li class="i1">on Nepa,
-    <a href="#Page_89">89</a>;</li>
-  <li class="i1">on Water Mites,
-    <a href="#Page_114">114</a>;</li>
-  <li class="i1">on Woodlice,
-    <a href="#Page_156">156</a>;</li>
-  <li class="i1">on Dytiscus larva,
-    <a href="#Page_158">158</a>,
-    <a href="#Page_159">159</a>.</li>
-</ul>
-
-<ul>
-  <li>Tailed Wasp,
-    <a href="#Page_82">82</a>.</li>
-
-  <li><i>Talitrus locusta</i>,
-    <a href="#Page_151">151</a>;</li>
-  <li class="i1">Bate and Westwood on,
-    <a href="#Page_151">151</a>;</li>
-  <li class="i1">Mr. Robertson on,
-    <a href="#Page_152">152</a>.</li>
-
-  <li>Tanypus, larva of,
-    <a href="#Page_176">176</a>.</li>
-
-  <li>Tegetmeier, Mr. W. B., on destruction of shells,
-    <a href="#Page_34">34</a>.</li>
-
-  <li>Thomson, J. A., on Spiders,
-    <a href="#Page_100">100</a>.</li>
-
-  <li>Trap-door Spider,
-    <a href="#Page_97">97</a>.</li>
-</ul>
-
-<ul>
-  <li>Vertebrates,
-    <a href="#Page_28">28</a>.</li>
-</ul>
-
-<ul>
-  <li>Wart-eater,
-    <a href="#Page_81">81</a>.</li>
-
-  <li>Water Beetle, Margined,
-    <a href="#Page_31">31</a>;</li>
-  <li class="i1">the Great,
-    <a href="#Page_49">49</a>.</li>
-
-  <li>Water Boatman,
-    <a href="#Page_93">93</a>.</li>
-
-  <li>Water Bugs,
-    <a href="#Page_86">86</a>.</li>
-
-  <li>Water-devil,
-    <a href="#Page_157">157</a>.</li>
-
-  <li>Water Mites,
-    <a href="#Page_113">113</a>;</li>
-  <li class="i1">Swammerdam on,
-    <a href="#Page_114">114</a>;</li>
-  <li class="i1">De Geer on,
-    <a href="#Page_116">116</a>;</li>
-  <li class="i1">Dugès on,
-    <a href="#Page_117">117</a>;</li>
-  <li class="i1">Mainland on,
-    <a href="#Page_118">118</a>.</li>
-
-  <li>Water Scorpion,
-    <a href="#Page_86">86</a>.</li>
-
-  <li>Water-tiger,
-    <a href="#Page_157">157</a>.</li>
-
-  <li>Westwood on Locusta,
-    <a href="#Page_81">81</a>.</li>
-
-  <li>White, Gilbert, on Blatta,
-    <a href="#Page_64">64</a>.</li>
-
-  <li>Wing-cases,
-    <a href="#Page_41">41</a>.</li>
-
-  <li>Wireworm,
-    <a href="#Page_126">126</a>.</li>
-
-  <li>Wood, Rev. J. G., on lens stand,
-    <a href="#Page_15">15</a>.</li>
-
-  <li>Woodlice,
-    <a href="#Page_155">155</a>;</li>
-  <li class="i1">Swammerdam on,
-    <a href="#Page_156">156</a>.</li>
-
-  <li>Worms,
-    <a href="#Page_29">29</a>.</li>
-
-  <li>Wright, Mr. L., on microscopes,
-    <a href="#Page_16">16</a>.</li>
-</ul>
-
-<ul>
-  <li>Zeiss, lenses of,
-    <a href="#Page_15">15</a>.</li>
-</ul>
-
-<p class="center xs">THE END.</p>
-
-
-<div class="footnotes"><h3>FOOTNOTES:</h3>
-
-<div class="footnote">
-
-<p><a id="Footnote_1" href="#FNanchor_1" class="label">[1]</a> Darwin, <i>Descent of Man</i> (2nd ed.), p. 159, note 23.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_2" href="#FNanchor_2" class="label">[2]</a> The power of magnification of a lens is the ratio of its
-focal distance to 10 inches. Thus a lens of 1 inch focus (or focal
-distance) magnifies 10 times (written × 10, or ten diameters); one of ½
-in. focal distance, 20 times, and so on.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_3" href="#FNanchor_3" class="label">[3]</a> <i>A Popular Handbook to the Microscope</i>, p. 39.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_4" href="#FNanchor_4" class="label">[4]</a> <i>Journal of the Quekett Microscopical Club</i>, v. 148.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_5" href="#FNanchor_5" class="label">[5]</a> <i>Ponds and Rock Pools</i>, p. 17.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_6" href="#FNanchor_6" class="label">[6]</a> <i>Bulletin of the Illinois State Laboratory of Natural
-History</i>, iv. 158.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_7" href="#FNanchor_7" class="label">[7]</a> ‘Dytiscus’ is written of set purpose. It is not, as
-some people tell us, a miswriting for Dyticus; but a properly
-formed diminutive, from the Greek <i>dutēs</i> = a diver; like
-<i>paidiskos</i> = a little boy. Linnaeus consistently calls the
-genus Dytiscus from 1735 onwards. Dyticus only dates from Geoffroy’s
-<i>Histoire Abrégée des Insectes</i>, first published anonymously in
-1762. On this question of nomenclature I am glad to have the support
-of the Rev. T. R. R. Stebbing, F.R.S., who, in answer to my inquiries,
-kindly wrote, ‘Darwin uses “Dytiscus” in the <i>Origin of Species</i>,
-and I should decidedly recommend its being upheld.’</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_8" href="#FNanchor_8" class="label">[8]</a> April 4, 1896.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_9" href="#FNanchor_9" class="label">[9]</a> <i>Popular History of the Aquarium</i>, p. 258.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_10" href="#FNanchor_10" class="label">[10]</a> May 2, 1896.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_11" href="#FNanchor_11" class="label">[11]</a> International Science Series, No. lxv.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_12" href="#FNanchor_12" class="label">[12]</a> <i>Aquatic Insects</i>, pp. 55, 56.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_13" href="#FNanchor_13" class="label">[13]</a> <i>Zeitschrift f. wiss. Zoologie</i>, Bd. xl. S. 481.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_14" href="#FNanchor_14" class="label">[14]</a> <i>Mémoires du Muséum d’histoire naturelle</i>, xviii.
-454 sqq.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_15" href="#FNanchor_15" class="label">[15]</a> I have purposely given <i>Blatta</i> as the generic name,
-rather than <i>Stilopyga</i>, which should properly be used, as the
-former is only employed in very recent literature.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_16" href="#FNanchor_16" class="label">[16]</a> Miall and Denny, <i>The Cockroach</i>, p. 20.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_17" href="#FNanchor_17" class="label">[17]</a> <i>Cambridge Natural History</i>, v. 231.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_18" href="#FNanchor_18" class="label">[18]</a> <i>The Senses of Animals</i>, p. 44.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_19" href="#FNanchor_19" class="label">[19]</a> <i>Cambridge Nat. Hist.</i> v. 223.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_20" href="#FNanchor_20" class="label">[20]</a> <i>Book of Nature</i>, p. 94.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_21" href="#FNanchor_21" class="label">[21]</a> This refers to the gizzard. <i>Echinus</i> was used to
-denote the third stomach of Ruminants (now called the manyplies),
-because it was thought to resemble a hedgehog rolled up.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_22" href="#FNanchor_22" class="label">[22]</a> Miall and Denny, <i>The Cockroach</i>, p. 118 (note).</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_23" href="#FNanchor_23" class="label">[23]</a> <i>Introduction to Entomology</i>, letter xi.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_24" href="#FNanchor_24" class="label">[24]</a> <i>Proceedings of the Zoological Society</i>, 1892, p.
-586.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_25" href="#FNanchor_25" class="label">[25]</a> <i>Our Household Insects</i>, pp. 159–163.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_26" href="#FNanchor_26" class="label">[26]</a> Kirby and Spence, <i>Introd. to Entomology</i>, ed. 1870,
-p. 484.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_27" href="#FNanchor_27" class="label">[27]</a> <i>Cambridge Natural History</i>, v. 318.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_28" href="#FNanchor_28" class="label">[28]</a> <i>The Senses of Animals</i>, p. 75.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_29" href="#FNanchor_29" class="label">[29]</a> J. Arthur Thomson, <i>Outlines of Zoology</i>, p. 288.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_30" href="#FNanchor_30" class="label">[30]</a> <i>Science for All</i>, ii. 178.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_31" href="#FNanchor_31" class="label">[31]</a> <i>British Spiders</i>, p. 10.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_32" href="#FNanchor_32" class="label">[32]</a> <i>British Spiders</i>, p. 359.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_33" href="#FNanchor_33" class="label">[33]</a> <i>Naturalist in La Plata</i>, p. 188.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_34" href="#FNanchor_34" class="label">[34]</a> <i>Mémoires</i>, vii. p. 304 sqq.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_35" href="#FNanchor_35" class="label">[35]</a> <i>Book of Nature</i>, pp. 101, 102.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_36" href="#FNanchor_36" class="label">[36]</a> <i>Mémoires</i>, vii. 144, 145.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_37" href="#FNanchor_37" class="label">[37]</a> The specimen was kindly identified for me, by Dr.
-Trouessart of Paris, as a nymph of <i>Hydrachna globula</i> (Dugès),
-and has been deposited in the British Museum (Natural History).</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_38" href="#FNanchor_38" class="label">[38]</a> <i>Mémoires</i>, vii. 123–128.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_39" href="#FNanchor_39" class="label">[39]</a> <i>Cambridge Natural History</i>, vol. v. ch. ii.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_40" href="#FNanchor_40" class="label">[40]</a> <i>Nature</i>, Dec. 12, 1895.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_41" href="#FNanchor_41" class="label">[41]</a> <i>Mémoires</i>, vii. 569.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_42" href="#FNanchor_42" class="label">[42]</a> <i>Crustacea</i>, p. 7.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_43" href="#FNanchor_43" class="label">[43]</a> <i>Crustacea</i>, p. 225.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_44" href="#FNanchor_44" class="label">[44]</a> International Science Series, No. lxxv.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_45" href="#FNanchor_45" class="label">[45]</a> ‘A limb is <i>chelate</i> when it has joints that will
-act together like a pair of tongs. Generally this character is produced
-by the hinging of the seventh joint a considerable way down on the side
-of the sixth. When the seventh joint, or finger, can be folded back
-upon the sixth, although the latter is not produced into any thumb-like
-process to oppose it, the limb is then said to be <i>sub-chelate</i>,
-the claw being in that case partial, though often extremely efficient.’
-Stebbing, <i>Crustacea</i> (International Science Series, lxxiv), p.
-45.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_46" href="#FNanchor_46" class="label">[46]</a> <i>Popular History of the Aquarium</i>, p. 223.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_47" href="#FNanchor_47" class="label">[47]</a> Lubbock, <i>Senses of Animals</i> (International Science
-Series, lxv.), p. 93.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_48" href="#FNanchor_48" class="label">[48]</a> <i>Aquarium</i> (ed. 1856), pp. 41, 42.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_49" href="#FNanchor_49" class="label">[49]</a> <i>Crustacea</i> (International Science Series, lxxiv),
-pp. 8, 9.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_50" href="#FNanchor_50" class="label">[50]</a> Bate and Westwood, <i>British Sessile-eyed Crustacea</i>,
-i. 8.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_51" href="#FNanchor_51" class="label">[51]</a> <i>Trans. Connecticut Academy</i> (1882), iv. 274, 275,
-note.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_52" href="#FNanchor_52" class="label">[52]</a> <i>Ponds and Rock Pools</i>, p. 118.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_53" href="#FNanchor_53" class="label">[53]</a> <i>British Sessile-eyed Crustacea</i>, i. 21.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_54" href="#FNanchor_54" class="label">[54]</a> <i>Proceedings Nat. Hist. Soc. Glasgow</i>, vol. i. pt.
-ii. n. s. pp. 130–132.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_55" href="#FNanchor_55" class="label">[55]</a> <i>British Sessile-eyed Crustacea</i>, ii. 381.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_56" href="#FNanchor_56" class="label">[56]</a> <i>Book of Nature</i>, i. 174.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_57" href="#FNanchor_57" class="label">[57]</a> <i>Mémoires</i>, iv. 386.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_58" href="#FNanchor_58" class="label">[58]</a> <i>Proceedings Boston Society of Natural History</i>,
-xxi. 223–228.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_59" href="#FNanchor_59" class="label">[59]</a> <i>Natural History of Aquatic Insects</i>, p. 47.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_60" href="#FNanchor_60" class="label">[60]</a> <i>Mémoires du Museum</i>, xviii. 442, 443.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_61" href="#FNanchor_61" class="label">[61]</a> <i>Mémoires</i>, vi. 352–55.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_62" href="#FNanchor_62" class="label">[62]</a> <i>Diptera</i>, iii. 281.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_63" href="#FNanchor_63" class="label">[63]</a> <i>Cambridge Natural History</i>, v. 494.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_64" href="#FNanchor_64" class="label">[64]</a> <i>Mémoires pour servir</i>, i. 577 sqq.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_65" href="#FNanchor_65" class="label">[65]</a> <i>Bulletin of the Illinois State Laboratory of Natural
-History</i>, iv. 167.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_66" href="#FNanchor_66" class="label">[66]</a> W. Evans, <i>Trans. Entomol. Soc.</i> (London), iv. 261.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_67" href="#FNanchor_67" class="label">[67]</a> <i>Mémoires pour servir</i>, t. vi. Plate 31.</p>
-
-</div>
-
-<div class="footnote">
-
-<p><a id="Footnote_68" href="#FNanchor_68" class="label">[68]</a> <i>Mémoires du Muséum</i>, t. xix. pp. 103, 104.</p>
-
-</div>
-</div>
-
-<p class="transnote">Transcriber’s Notes:<br />
-
-1. Obvious printers’, punctuation and spelling errors have been
-   corrected silently.<br />
-
-2. Some hyphenated and non-hyphenated versions of the same words have
-   been retained as in the original.</p>
-
-
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