THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 PRESENTED BY 
 
 PROF. CHARLES A. KOFOID AND 
 MRS. PRUDENCE W. KOFOID 
 
THE "SHOWN TO THE CHILDREN" SERIES 
 EDITED BY LOUEY CHISHOLM 
 
 THE MICROSCOPE 
 
The 
 44 Shown to the Children " Scries 
 
 i. BEASTS. 
 
 With 48 Coloured Plates by PERCY J. BILLING- 
 HURST. Letterpress by LENA DALKEITH. 
 a. FLpWERS. 
 
 With 48 Coloured Plates showing 1 50 flowers, by J ANET 
 HARVEY KELMAN. Letterpress by C. E. SMITH. 
 
 3. BIRDS. 
 
 With 48 Coloured Plates by M. K. C. SCOTT. 
 Letterpress by J. A. HENDERSON. 
 
 4. THE SEA-SHORE. 
 
 With 48 Coloured Plates by JANET HARVEY KELMAN. 
 Letterpress by Rev. THEODORE WOOD. 
 
 5. THE FARM. 
 
 With 48 Coloured Plates by F. M. B. and A. H. 
 BLAIKIB. Letterpress by FOSTER MEADOW. 
 
 6. TREES. 
 
 With 32 Coloured Plates by JANET HARVEY KELMAN. 
 Letterpress by C. E. SMITH. 
 
 7. NESTS AND EGGS. 
 
 With 48 Coloured Plates by A. H. BLAIKIE. Letter- 
 press by J. A. HENDERSON. 
 
 8. BUTTERFLIES AND MOTHS. 
 
 With 48 Coloured Plates by JANET HARVEY KELMAN. 
 Letterpress by Rev. THEODORE WOOD. 
 
 9. STARS. 
 
 By ELLISON HAWKS. 
 
 10. GARDENS. 
 
 With 32 Coloured Plates by J. H. KELMAN. Letter- 
 press by J. A. HENDERSON. 
 
 xi. BEES. 
 
 By ELLISON HAWKS. Illustrated in Colour and 
 Black and White. 
 
 . ARCHITECTURE. 
 
 By GLADYS WYNNE. Profusely Illustrated. 
 
 13. THE EARTH. 
 
 By ELLISON HAWKS. Profusely Illustrated. 
 
 14. THE NAVY. 
 
 By PERCIVAL A. HISLAM. 48 Two-colour Plates. 
 
 15. THE ARMY. 
 
 By A. H. ATTERIDGE. 16 Colour and 32 Black Plates. 
 
 16. WORK AND WORKERS. 
 
 By ARTHUR O. COOKE. 48 Illustrations. 
 
 17. THE MICROSCOPE. 
 
 By ELLISON HAWKS. Illustrated in Colour and 
 Black and White. 
 
drawing by 
 
 Volvox 
 
 [G. Fisher-Jones 
 
The Microscope 
 
 BY 
 
 CAPTAIN ELLISON HAWKS 
 
 Author of "Stars," "Bees," "The Earth," Shown to the Children 
 
 "The Boy's Book of Astronomy," "The Romance of Water 
 
 in Nature," etc.; and Editor of Messrs. Jack's 
 
 "Romance of Reality" Series 
 
 THOMAS NELSON AND SONS 
 
 NEW YORK 
 
TO 
 MY YOUNG FRIEND 
 
 JOHN 
 
 THIS BOOK IS AFFECTIONATELY 
 DEDICATED 
 
CONTENTS. 
 
 I THE STORY OF THE MICROSCOPE . . n 
 
 II. THE PRINCIPLE OF THE COMPOUND MICRO- 
 SCOPE . . . . . 16 
 
 III. WORKING WITH THE MICROSCOPE . ' . 30 
 
 IV. MICROSCOPIC PLANTS . . . . . . 40 
 
 V. MICROSCOPIC ANIMALS . . . . . 53 
 
 VI. DAPHNIA AND CYCLOPS . . . . 65 
 
 VII. PLANT LIFE . . . . ... 73 
 
 VIII. FLOWERS V. 87 
 
 IX. FUNGI AND MOULDS ..... 95 
 
 X. MARINE LIFE . . . . . . . 104 
 
 XL AN INSECT LABORATORY AND WORKSHOP : 
 
 THE HONEY-BEE . . . ; . 115 
 
 XII. OTHER INSECTS . . . . * 130 
 
 XIII. MINIATURE ENGINEERS : SPIDERS . i 147 
 
ABOUT THIS BOOK. 
 
 DEAR JOHN, 
 
 Many years ago I remember reading a fairy 
 tale called, I think, The Rose-Coloured Spectacles. It 
 told of a wonderful pair of spectacles which caused 
 everything to appear different to the person who was 
 wearing them. Things looked so very changed as seen 
 through these rose-coloured spectacles and so many 
 new features were discerned, that people came from far 
 and wide to look through them. 
 
 Unfortunately the secret of the manufacture of the 
 rose-coloured spectacles has never been discovered. 
 An instrument has been made, however, which nearly 
 approaches them, and actually surpasses them in the 
 wonderful things it shows. This instrument is the 
 Microscope, and in this little book I shall endeavour 
 to help you to look through it and to see some of the 
 wonderful things it reveals in the great realm of Nature. 
 
 Almost any object, no matter how commonplace, will 
 show new features of interest when magnified. You will 
 readily understand, therefore, that in this little book 
 I cannot attempt to tell you how everything looks, as 
 seen with the microscope in fact, no one could write 
 
 (2,084) 9 2 
 
io ABOUT THIS BOOK. 
 
 such a book. There are so many interesting objects tc 
 write about, indeed, that it has been difficult for me to 
 decide what was to be included and what was to be left 
 out. I felt, however, that you would like most of all 
 to hear of what the microscope reveals in objects of 
 everyday interest ; that you want to know what such 
 things as pollen and plant cells look like, and to learn 
 exactly by what means a spider spins its web and a bee 
 stings. Therefore, practically all the objects I have 
 described are such as any one may see if he or she be 
 the fortunate possessor of a microscope even though 
 it may not be a very powerful one. Not only may you 
 see these objects, but from the little I have told you 
 about them, you will be able to understand them, to 
 know something of their life-history and of the part 
 they play in Nature. 
 
 I feel sure you will join me in giving thanks to 
 my friends who have kindly assisted me with some of 
 the illustrations. To Mr. G. Fisher-Jones, F.R.M.S., 
 for the very beautiful coloured plates so accurately and 
 artistically drawn. To Mr. Chas. D. Holmes, Mr. A. E. 
 Smith, Mr. E. A. Pinchin, Mr. W. Brough-Randles, B.Sc., 
 Mr. W. Coles-Finch, Mr. J. Holmes ; and to Messrs. 
 Flatters, Ltd., and to Messrs. Pathe Freres. My in- 
 debtedness to Captain W. R. Booth and Mr. Chas. D. 
 Holmes for reading over the proofs must also be 
 mentioned. 
 
 Yours truly, 
 
 ELLISON HAWKS. 
 
 io GRANGE TERRACE, LEEDS, 
 November 1919. 
 
THE MICROSCOPE. 
 
 CHAPTER I. 
 THE STORY OF THE MICROSCOPE. 
 
 I. 
 
 THE microscope derives its name from two Greek 
 words, mikros, " small," and skopeo, " to see or 
 observe." A microscope presents to the eye of its user a 
 magnified image of the object under examination. The 
 simplest form of microscope is an ordinary lens, such as a 
 reading glass or pocket magnifier. With the help of a low- 
 powered microscope we are able to magnify objects so 
 that there become visible details which cannot be seen 
 with the naked eye. By means of a more powerful 
 instrument we are able to see objects which are other- 
 wise quite invisible, and of the existence of which we 
 should probably remain in complete ignorance but for 
 the microscope. 
 
 The microscope may thus be likened to a window 
 through which we are able to look upon a new and 
 wonderful Fairyland. Here objects measuring no more 
 
 than a quarter of a millionth part of an inch in size are 
 
 11 
 
12 THE MICROSCOPE. 
 
 revealed to us, and made to record themselves on the 
 photographic plate. A drop of water from a pond may 
 be so magnified that we find it is almost a world in itself, 
 containing specimens of minute vegetable and animal 
 life. The very construction and origin of these minute 
 forms of life are often such as to present to us the most 
 difficult problems, which even our cleverest scientists 
 and chemists are unable to successfully and completely 
 solve. 
 
 Again, a pinch of knife polish may contain microscopic 
 shells, which are really the skeletons of minute creatures 
 which lived ages ago. These shells are so delicate and 
 beautiful in appearance that our greatest artists would 
 gladly use them as patterns for designs if they could. 
 So I might go on, pointing out to you the wonders which 
 the invention of the microscope has laid bare to the gaze 
 of all who care to look. 
 
 II. 
 
 The actual date of the invention of the microscope 
 and the name of its inventor are unknown. It has been 
 said that magnifying glasses were known to the ancient 
 Egyptians, but whether this was so or not now appears 
 uncertain. In the first century, Seneca the tutor of 
 the infamous Roman Emperor Nero noticed that if a 
 globe of glass be filled with water, writing seen through 
 it appeared larger than it really was. Galen, the learned 
 Greek physician, tells us definitely that magnifying 
 glasses were certainly not known to the Greeks and 
 Romans in the first and second centuries. Much later 
 in the eleventh century the Arabians seemed to have 
 
PLATE II 
 
 From a water-colour drawing by] [G. Fisher-Jones 
 
 1. Desmida 
 
 (a) Arthrodesm-us, (l>) Closteriutn, (c) Desmidium, (d) Euasirnm, (e) Pediastritin, 
 (/) Scenedesiiius, (^-) Tetaieniorus, (/i) Xantliidium. 
 
 2. Stages of division of a Desmid 
 Afic.rasterias, forming two individuals. 
 
ROGER BACON. 13 
 
 known and used some form of magnifying glass. Beyond 
 these few facts nothing of importance has been discovered 
 of any early evidences of magnifying glasses, and until 
 the thirteenth century very little appears to have been 
 known about them. 
 
 In 1276, however, Roger Bacon a Franciscan monk 
 of Ilchester presented his Opus Majus to Pope 
 Clement IV. In this interesting volume Roger Bacon 
 showed how crystal lenses could be used to make objects 
 appear larger. " With these lenses," he said, " an instru- 
 ment could be made, useful to old men and to those whose 
 sight is weakened, for by means of it they would be able 
 to see letters, however small they are, made large and 
 clear. . . ." 
 
 In the days when Roger Bacon lived people did not 
 understand science as we do to-day, believing in sorcery 
 and witchcraft. They thought that any one who had 
 discovered lenses such as those described by Roger 
 Bacon must indeed have gone to the devil himself for 
 assistance ! It was ordered, therefore, that he should be 
 cast into prison. His Opus Majus was hidden away 
 perhaps by some of his friends, but this we do not know 
 and remained lost until discovered in 1733, nearly five 
 hundred years later. By this time a form of microscope 
 had been in use for over one hundred years, and Roger 
 Bacon was thus robbed of the credit of the discovery, 
 as well as, perhaps, of the discovery of the telescope. 
 
 Many careful investigations have been made in the 
 attempt to find who constructed the first microscope. 
 It is now believed that it was made at some date between 
 1590 and 1609, and that the credit for the invention 
 
14 THE MICROSCOPE. 
 
 must be given to one of three spectacle makers of Middel- 
 burg in Holland Hans Janssen, his son Zacharias, or 
 Hans Lippershey. 
 
 One of the earliest accounts of the microscope and of 
 observations with the instrument was given in 1665, by 
 the celebrated Dr. Robert Hooke. It was published 
 in a large volume called Micrographia, a copy of which 
 is to be seen in the British Museum. Dr. Hooke 
 describes his microscope as having a tube : "... for 
 the most part not above six or seven inches long, though 
 by reason that it had four drawers it could easily be 
 lengthened as occasion required. . . ." 
 
 We shall shortly learn that microscopes are of two 
 kinds, called simple and compound. The instrument 
 used by Dr. Hooke was of the compound type, and is the 
 same in principle as most of the microscopes of the 
 present day. 
 
 Some few years after Dr. Hooke published his Micro- 
 graphia another worker, named Leeuwenhoek, made a 
 simple microscope, and in 1673 communicated some 
 of his discoveries to the Royal Society. He did not 
 describe his instrument, however, but when he died he 
 left to the Royal Society a cabinet containing twenty-six 
 of his microscopes. His work is of importance because 
 it then came to be believed that the form of microscope 
 he used that is, the simple type was better than the 
 compound type advocated by Dr. Hooke. Because of 
 Leeuwenhoek's work the compound microscope fell into 
 disrepute, and no improvements in it were effected for a 
 considerable time. 
 
BENJAMIN MARTIN. 15 
 
 To Benjamin Martin is due the credit for many advances 
 on the earlier models. In 1742 he made an ingenious 
 microscope and gave it to George III., and this instru- 
 ment is now in the possession of the Royal Microscopical 
 Society. It was, perhaps, the best microscope of any 
 made up to that time. Professor Quekett, a well-known 
 microscopist, has described it, saying that it is about 
 two feet high, and is supported on a tripod base. The 
 body, three inches in diameter, is composed of two tubes, 
 which can be raised or lowered. There are twenty-four 
 lenses, and these have been very carefully constructed. 
 
 Martin was quickly followed by numerous other workers, 
 and during the ensuing years the microscope rapidly 
 developed. These early microscopes were very crude 
 and imperfect, and were you able to see one you would 
 probably be very puzzled to know what kind of an 
 instrument it could be, even though you knew what a 
 modern microscope looks like. As time went on, how- 
 ever, and the manufacture of glass lenses gradually 
 became more perfect, microscopists were able to improve 
 on the early ideas, and little by little the wonderful 
 microscope of to-day was perfected. 
 
 The microscope may be said to be one of our most 
 recent instruments, for its true principles were not 
 generally known until about 1881. 
 
CHAPTER II. 
 
 THE PRINCIPLE OF THE COMPOUND 
 MICROSCOPE. 
 
 I. 
 
 THE microscope or indeed any magnifying glass 
 acts in the same way as the crystalline lens of our 
 eyes and depends upon refraction. Refraction may be 
 thus explained. When a ray of light passes through 
 one substance or medium, as it is called into another 
 of different density, the path of the ray is bent or re- 
 fracted. Thus, a ray of light passing from air into water 
 is refracted, because water is of different density to air. 
 This may be clearly seen by putting a pencil or other 
 object into a basin of water. The pencil appears to 
 be bent or broken at the point where it enters the water 
 (see a, Fig. i). Why this should be so is shown in 
 b, Fig. i, where we see indicated the path of a ray of light 
 coming from the end of the pencil to the eye. At the 
 point where the ray comes out of the water it is bent ; 
 but the eye does not see this, and instead of our being 
 able to perceive the true position of the end of the pencil, 
 we seem to see it lying on an imaginary line. A ray of 
 light passing through a lens is refracted in a similar 
 
 16 
 
PLATE III 
 
 From photo-micrographs by] 
 
 [E. Cuzner, F.R.M.S. 
 
 DISC-SHAPED DIATOMS 
 (a) Craspedodiscus. (b) Heliopelta 
 
REFRACTION. 17 
 
 manner, the amount of the refraction depending upon 
 the nature and curvature of the lens. 
 
 Seneca did not try to understand why writing looked 
 larger through a glass globe filled with water. Had he 
 
 &y 
 
 FIG. i. Experiment to illustrate refraction of rays. 
 
 done so he would have discovered that the curved surface 
 of a globe bends inward the rays of light, because glass 
 and water are more dense than air. It was by using this 
 principle that the microscope was thought of. 
 
 A lens refracts the rays from the object under examina- 
 tion to an eyepiece, and it is here that the eye is placed. 
 The point at which the rays from the lens gather is 
 called the focus. At this point is formed an image of 
 the object, and this is magnified by the eyepiece. 
 
 The principle may be explained in a rough way by 
 comparing the lens to a funnel placed in a bottle. If placed 
 in the rain the bottle is filled more quickly than would 
 be the case if no funnel were used. A lens collects not 
 raindrops but rays of light, and directs them to the eye 
 of the observer (Fig. 2). By these means the eye is 
 
 (2,084) 3 
 
18 THE MICROSCOPE. 
 
 enabled to grasp more rays than it would do if a lens 
 were not used in other words, the object appears mag- 
 nified. 
 
 The same principle is the basis of opera-glasses, tele- 
 
 lens 
 
 FIG. 2. Lens collecting rays of light. 
 
 scopes, and spectacles. The latter were at first (about 
 1285) called " magic glasses," because the ignorant people 
 did not know of the simple principle upon which they 
 are based. 
 
 II. 
 
 I have already mentioned that microscopes are of two 
 kinds, simple and compound. A simple microscope con- 
 sists of a single lens, or sometimes of two such lenses 
 placed close together. It will magnify an object ten or 
 
 (a) XX "- (I/) 
 
 FIG. 3. Pocket lenses. 
 
 (c) 
 
 twenty times. Simple microscopes are in everyday use 
 as reading glasses and similar appliances. A more com- 
 pact form is the pocket lens, three types of which are 
 shown in Fig. 3. The form which is most useful is that 
 shown at b, being fitted with three lenses and a " stop," 
 
THE COMPOUND MICROSCOPE. 19 
 
 or small hole, which enables a clearer image to be obtained. 
 Different magnifications may be obtained by using the 
 various lenses separately, and still greater magnification 
 is possible by using a combination of two or of all three 
 lenses. Leeuwenhoek's microscope was an improvement 
 
 Eye Lens 
 
 Field Lens 
 
 T, 
 
 r ~\ [ 
 
 >l 
 
 BodgTube ... 
 Draw Tube 
 
 
 i 
 
 !l 
 
 S&. ~flM 
 
 Exje Piece 
 
 JDrmu Tube 
 
 Objective 
 Cover Glaff 
 
 Glass Slide 
 FIG. 4. Section of a microscope showing the principal parts. 
 
 on a simple lens, for sometimes it magnified the object 
 under examination 270 times. 
 
 The compound microscope, in which we are more par- 
 ticularly interested, consists of two sets of lenses (Fig. 4). 
 The first set is placed at that end of the tube which is 
 nearest the object to be examined, and is therefore called 
 
20 THE MICROSCOPE. 
 
 the " objective." The second set of lenses is situated 
 at the other end of the tube and is called the " eyepiece," 
 because it is nearest to the observer's eye. The objective 
 collects the rays of light from the object under examina- 
 tion, bends them inward, and sends them to the focus. 
 Here they form a minute image of the object. At the 
 focus they cross each other and diverge into a broadening 
 stream. Soon they reach the eyepiece, which further 
 
 Lenses 
 
 FIG. 5. Microscope objective. 
 
 magnifies the image and again bends the rays and directs 
 them to the eye of the observer. 
 
 The objective (Fig. 5) is detachable and can be un- 
 screwed easily from the microscope, so that another 
 objective of lower or higher power may be put on in its 
 place. The objective is the most powerful and the most 
 expensive part of a microscope. In a very good instru- 
 ment this one part alone may cost up to 25. An 
 advanced worker with the microscope will probably 
 require six, or more, objectives. 
 
PLATE IV 
 
 \ 
 
 r 
 s t 
 
 
 
 I 
 
THE BINOCULAR MICROSCOPE. 
 
 21 
 
 In most microscopes to-day there is only one tube, 
 and therefore only one eye can be used for observing. 
 To some people this is often very fatiguing and causes 
 a great strain upon the observer. In 1860 Wenham 
 invented the binocular microscope, 
 consisting of two tubes and two eye- 
 pieces (Fig. 6). By an ingenious 
 device two images are formed from 
 one object, and it is thus made 
 possible to employ both eyes for 
 observing. The binocular micro- 
 scope is not generally used, however, 
 most people finding the single tube 
 instrument satisfactory. 
 
 III. 
 
 From the description I have just 
 given of the principles of the micro- 
 scope you will readily understand 
 that the glass from which the lenses 
 are made plays an all-important 
 part in its construction. It was be- 
 cause of a defect in the lenses that 
 the microscopes of earlier days could 
 not be developed beyond a certain point. To understand 
 the reason of this, and the clever manner in which the 
 difficulty was overcome, it is necessary to learn some- 
 thing of the two forms of lenses used. These are called 
 " convex " and " concave " (Fig. 7). A convex lens is 
 thicker in the middle than at the edges, and may be said 
 to bulge outwards. A concave lens is just the opposite, 
 
 FIG. 6. Section of 
 Binocular Micro- 
 scope. 
 
22 THE MICROSCOPE. 
 
 for it is thicker at the edges, has a saucer-like hollow in 
 the centre, sinking inwards. A convex lens bends or 
 refracts rays inwards, but a concave lens refracts them 
 outwards. 
 
 Because of the peculiar shape of a lens, and the conse- 
 
 CONVKX CONCAVE 
 
 ACHROMATIC 
 
 FIG. 7. Three types of lenses. 
 
 quent difference in density of various parts where it is 
 thicker or thinner, the rays are not all refracted to a 
 similar amount. For instance, those rays which fall 
 near the edge of a convex lens have not to pass through 
 so much glass as those rays which fall on or near the centre 
 of the lens. Consequently, on passing through a lens the 
 rays follow different paths and do not all meet together 
 exactly at the focus. A distorted and blurred image is 
 then formed. This fault is called " spherical aberration." 
 It can be overcome by fitting into the uncorrected lens 
 a second lens, of a different shape from the original. 
 When this is done all the rays are brought exactly to the 
 same focus. 
 
 A second and more troublesome defect is a peculiar 
 colouring called " chromatic aberration " caused by 
 the lenses. We have been speaking of rays of light for 
 the sake of clearness and as though they formed a simple 
 stream of light. White light passing through a prism 
 
THE SPECTRUM. 23 
 
 of glass issues from it as a coloured band. No doubt you 
 have often noticed this when sunlight falls on a cut glass 
 pendant of a chandelier or similar object. This band of 
 coloured light is called the spectrum (Fig. 8). It con- 
 tains certain colours which merge gradually into one 
 another. They are always found in the spectrum in 
 the following order : red, orange, yellow, green, blue, 
 indigo, and violet. These colours are combined in white 
 
 FIG. 8. How the spectrum is formed. 
 
 light and are therefore invisible to us in ordinary circum- 
 stances. 
 
 When a ray of light passes through a concave or convex 
 lens the same occurrence takes place as in the case of the 
 prism. The white light is broken up into the above- 
 mentioned colours. Each of these colours has what is 
 called a different wave-length, that of red being much 
 longer than that of violet. The consequence of this, in 
 regard to the microscope, was that on passing through 
 the lenses light was broken up into its component colours 
 of varying wave-lengths, and each colour gave a faint 
 but separate image of the object under examination. 
 This was a great drawback, of course, because instead 
 of the observer seeing a clear, well-focused image he saw 
 
24 THE MICROSCOPE. 
 
 a blurred image looking like " all the colours of the 
 rainbow." 
 
 For many years opticians regarded it as impossible 
 to overcome chromatic aberration. Clearly the remedy 
 was to bring all the coloured images together at one focus 
 in other words, to make the rays all of the same wave- 
 length. It was realized that unless this seemingly im- 
 possible task could be effected, the compound microscope 
 could never be perfect. If several kinds of glass of differ- 
 ent densities could have been used, the difficulty might 
 have been overcome. This seemed a forlorn hope, how- 
 ever, for only two kinds of glass were known, crown 
 and flint glass. The latter kind is denser than the former, 
 and with a lens made partly of each it was possible to 
 correct two colours ; but as the light-waves of the other 
 colours remained unconnected, there was still formed a 
 series of confusing faint images. 
 
 IV. 
 
 About 1881 two Germans Abbe, Professor of Mathe- 
 matics at Jena, and Dr. Schott, who was interested in 
 glass-making began a series of researches and experi- 
 ments, aided by their Government. Professor Abbe had 
 studied optics since 1873 and worked on lines which were 
 quite original. He was able to decide on paper the 
 density he required the glass for his lenses, and also exactly 
 the curve the surfaces needed. In 1884 a microscope 
 was made which was not only constructed on new prin- 
 ciples, but had lenses of a new kind of glass, called fluor- 
 glass. 
 
 To understand more fully the value of this advance 
 
PLATE V 
 
THE INVISIBLE RAYS. 25 
 
 in the construction of the microscope we must learn 
 something more of the varying lengths of the light rays. 
 We have already mentioned that violet rays are shorter 
 than red rays. It is found that by employing the shorter 
 rays more details in a minute object become visible. 
 In fact, so much is this the case that by violet rays objects 
 may be distinguished which are twice as small as those 
 which can be seen by the longer red rays. 
 
 The violet rays are not the shortest of all known waves 
 of light, for beyond them in the spectrum are the ultra- 
 violet rays (see Fig. 8) . These ultra-violet rays are most 
 curious, for, no matter how long we may look at the 
 coloured band of light from a prism, we cannot discern 
 them. They are invisible to the human eye and have 
 never been seen, for their length is so short that they 
 make no impression upon our retina. The ultra-violet 
 rays can, however, be photographed or rather photo- 
 graphs can be taken by them and so we know of their 
 existence. 
 
 We can now better understand the next problem which 
 confronted Professor Abbe. He knew that by means 
 of the short violet rays objects which could not be seen 
 with the long red rays might be made visible. He 
 believed from this that if he could use the ultra-violet 
 rays he would be able to make the microscope many 
 times more powerful than it was, even with the violet 
 rays. To attain his object he had to deal with rays he 
 could not see, and there was no known kind of glass which 
 was capable of refracting the ultra-violet rays in the 
 same way in which crown and flint glass refract the 
 ordinary rays. 
 
 (2,084) * 
 
26 THE MICROSCOPE. 
 
 Professor Abbe was not dismayed by such difficulties 
 as these. After many experiments, the firm of opticians 
 with whom he was associated succeeded in making lenses 
 of molten quartz. These lenses could be used to refract 
 the ultra-violet rays as required, but of course the image 
 formed still remained invisible to the human eye. Even 
 Professor Abbe could not render the ultra-violet rays 
 optically visible, and so it is that objects can only be 
 examined by these rays by photography. 
 
 Through the invention of quartz-glass lenses it is some- 
 times possible to examine objects which are only anrsuTT 
 inch hi size. 
 
 V. 
 
 A microscope consists of the following important parts, 
 all of which are clearly indicated in Fig. 9. 
 
 (i) The body, generally a brass tube which carries, at 
 the bottom, (2) the objective, and, at the top nearest the 
 observer's eye, (3) the eyepiece. These parts are mounted 
 on (4) the limb, as is also (5) the stage, which may be fitted 
 with spring clips for holding the slide or object to be 
 examined. In more expensive instruments a mechanical 
 stage is fitted, which is easily moved from side to side or 
 upwards and downwards by milled-head spindles and 
 rackwork. Focusing is accomplished by (6) coarse 
 and fine adjustments, and a light is reflected on to the 
 object by (7) a mirror, fitted by a sliding clip to (8) the 
 tailpiece. All these parts are mounted on (9) the foot or 
 base. 
 
 If the object we are examining is thin and sufficiently 
 transparent to enable light to pass through it, it is 
 
PARTS OF A MICROSCOPE. 
 Eyepiece 
 
 27 
 
 Draw tube 
 
 Mi/led head for 
 coarse adjustment 
 
 Moscpiece 
 on JBody 
 for Objective 
 
 . SfirintfC/ipa 
 
 fornofdind 
 
 Object 
 
 Miffedhcad 
 for moving 
 Mechanical 
 
 Under-fitting 
 Miffed Avert 
 for raising 
 Sub stage 
 
 S 
 
 Mirror' 
 
 FIG. 9. Illustration distinguishing the various component parts 
 of a Compound Microscope. 
 
 placed upon the stage on a glass slip called a slide, and 
 light is reflected to it by the mirror (Fig. 10). If the 
 object is opaque, however, and it is impossible for light 
 
FIG. 10. Illuminating a specimen by means of transmitted light. 
 
 FIG. n. Illuminating a specimen by reflected light. 
 
PLATE VI 
 
THE CONDENSER. 29 
 
 to pass through it, a condenser must be used instead of 
 the mirror. The condenser consists of a lens generally 
 mounted on a separate stand which throws a beam of 
 concentrated light on to the object from above the 
 stage (Fig. n). 
 
CHAPTER III. 
 WORKING WITH THE MICROSCOPE. 
 
 I. 
 
 OME people think that it is of no use studying any 
 subject unless they can use the latest and most 
 costly instruments. It is true that a really good micro- 
 scope is expensive, costing anything from 5 to 50 or 
 even more. It is not necessary, however, to expend 
 even 5 on a microscope, for one could obtain much 
 entertainment and do really useful work with a " home- 
 made " microscope, which does not cost much more 
 than 55. Microscopes very suitable for studying the 
 objects described in these pages are to be purchased from 
 i to 5 second-hand. There are, of course, many objects 
 such as blood corpuscles and bacteria for the study 
 of which more powerful objectives are required ; but we 
 shall find that a simple form of microscope will reveal 
 sufficient wonders to our gaze to employ us for many 
 long evenings. 
 
 Galileo's telescope would be classed as a very crude 
 instrument in these days indeed, for a few shillings any 
 one can make an equally powerful instrument. But in 
 the hands of Galileo, this little " optick tube " explored 
 
USING A POCKET LENS. 31 
 
 the heavens, discovered the mountains on the Moon, the 
 spots on the Sun, and changed man's ideas of the con- 
 struction of the universe. 
 
 In his Life and Letters the famous scientist, Charles 
 Darwin, says the student should always see what he 
 can with a simple microscope before using a compound 
 instrument. He further says that he would be inclined 
 to suspect the work of a man who never used the simple 
 instruments. When he set out on his celebrated voyage 
 in the Beagle, Darwin took with him only a simple micro- 
 scope, for it was his custom to use simple methods and 
 few instruments in his work. 
 
 II. 
 
 It is a good plan to spend the fine days of summer in 
 collecting objects. After examining these, put away 
 those which will keep, until the dark nights of winter, 
 when sufficient time may be given to a lengthy and 
 detailed study of each. For examination purposes the 
 pocket lens will be found a valuable acquisition, espe- 
 cially if it is used correctly. It may seem unnecessary 
 for me to tell you how to use a pocket lens, but for those 
 unaccustomed to handling them it may be said that the 
 best way to look at an object is first to put the lens 
 close to the eye and then to bring it down, with your 
 head following it at the same time, to meet the object 
 under examination. When using a pocket lens it is 
 sometimes desirable to have one hand free for dissecting, 
 and the difficulty of working in these circumstances has 
 been overcome by a simple device, called the " focostat " 
 (Fig. 12). A single lens is mounted by a movable clip 
 
32 THE MICROSCOPE. 
 
 to the handle of the dissecting needle, and when once 
 the lens has been moved to the correct focus, it is quite 
 
 FIG. 12. The Focostat. This is fixed to the dissecting needle, 
 and leaves one hand free. 
 
 easy for us to see what we are doing with the needle 
 point. Another way of working so that one hand is free 
 
 FIG. 13. The " Third Hand " Magnifier. 
 
 is the " third-hand " magnifier, as it is called (Fig. 13). 
 This consists of a lens which is attached to the thumb 
 
PLATE VII 
 
 From a photo-micrograph byj 
 
 [A. H. Smith 
 
 A GROUP OF DIATOMS 
 
RECORDING OBSERVATIONS. 33 
 
 of the left hand by a clip, similar to the kind which are 
 used for attaching shades to candles. 
 
 A notebook should be kept, and may include some 
 record of where and how the specimens were obtained, 
 and later on, when they have been thoroughly examined 
 with the microscope an account of what is noticed 
 about them. It is a good plan, too, to make as many 
 sketches of the specimens as possible. It does not 
 matter if you cannot draw or paint, for even the roughest 
 sketch is better than none at all. It is found that by 
 sketching an object we notice details which might other- 
 wise escape our observation. For instance, could you 
 describe to me exactly the kind of chimney-pot on your 
 house ? Perhaps some of you could, but many could not. 
 Had you made a sketch of your house at some previous 
 time you would be able to say at once just what kind 
 of a chimney the house had, because in making your 
 sketch you would have had to study the detail of the 
 chimney-pots in order to draw them accurately. 
 
 When using a lens or a microscope, it is best not to 
 shut the eye which is not being used, as if this is done it 
 will soon become tired with being screwed up for any 
 length of time. With a little practice it is easy to train 
 the mind to see only with the eye at the lens, even though 
 the other eye is open. 
 
 III. 
 
 When collecting specimens it is useful to take two or 
 three glass tubes the kind in which cachous are sold 
 and if possible a glass-topped box. If we are collecting 
 specimens from a pond we take a small glass jar or a 
 
 (2,084) 5 
 
34 
 
 THE MICROSCOPE. 
 
 muslin net mounted on a stick (Fig. 14), and a little 
 drag, made by inserting three or four wire hooks in a 
 
 FIG. 14. (a) Glass jar wired to stick. 
 (b) Muslin net mounted on stick. 
 
 FIG. 15. Drag for obtaining 
 pond weeds. 
 
 piece of lead fastened to the end of a string (Fig. 15). 
 
 With this we can pull to the side of the pond pieces of 
 
 floating twig or weed. 
 
 A large bottle should also be taken, and if possible a 
 
 second one, known as a " concentrating bottle." This is 
 best made by obtaining one of those bottles 
 with a metal screw-top, such as contain 
 honey. Punch a number of small holes in 
 the metal top and solder a tin funnel in 
 the centre, the end of the funnel-pipe being 
 a few inches from the bottom of the bottle 
 (Fig. 16). Before screwing on the lid, 
 
 FIG. 16. Con- stret ch a piece of fine muslin over the top 
 
 bottL rating of the bottle< Water poured through the 
 funnel in the bottle will now overflow 
 through the holes in the lid, but the specimens it con- 
 tains are prevented from leaving the bottle by the muslin. 
 
COLLECTING SPECIMENS. 35 
 
 Thus the more water we pour into the bottle the more 
 numerous become the specimens it contains, so that we 
 take home with us in our bottle specimens contained in 
 bucketfuls of water. 
 
 Another useful instrument is a piece of glass tubing, 
 about | inch or one inch in diameter. One end is 
 left open, but at the other a piece of fine muslin is 
 fastened with an elastic band. The tube may be im- 
 mersed in the pond and the water allowed to flow through 
 it. The water passes down the tube and out at the end 
 where the muslin is fastened. The muslin acts as a 
 strainer, and retains minute specimens which may be 
 easily transferred to a bottle by removing the elastic 
 band. 
 
 Single specimens may be obtained by using a piece of 
 glass tube open at both ends. Place one finger over one 
 end of the tube and lower the other into the water so 
 that the end comes over the specimen to be captured. 
 If we take away our finger at the top of the tube, the 
 water rushes up, carrying the specimen with it. By 
 placing the finger at the top of the tube again, the tube 
 may be lifted and its contents released into a jar. 
 
 IV. 
 
 Objects for observation under the microscope may be 
 divided into two classes. The first are those which do 
 not require any preparation and may be observed at 
 once, such as simple plants. The greater number of 
 objects fall into the second class, however, and are 
 those which must be prepared and treated before all 
 the details of their structure may be made out. We can 
 
36 THE MICROSCOPE. 
 
 illustrate what is meant by this by taking the leg of 
 some insect and, without previous preparation, observing 
 it under the microscope. We see nothing but a dark 
 opaque body, looking like a silhouette, with possibly a 
 few hairs or specks of dust attached. If the leg be 
 correctly prepared, however, a very different aspect is 
 presented. In the first place, it is cleaned and rendered 
 transparent ; it is then seen to be beautifully coloured, 
 and every detail becomes visible. The delicate muscles 
 and membranes of the joints, the sharp claws and soft 
 pads are now clearly seen. 
 
 For the observation of the first class of objects a live 
 box is the best. This consists of a brass cell something 
 
 FIG. 17. A live box. 
 
 like a pill-box with brass sides (Fig. 17). The bottom 
 of the cell is formed by a piece of glass ; over it is a lid 
 or cover with a glass top which can be raised or lowered, 
 so as to press on the bottom glass if required. This 
 adjustment is very useful if we have a lively insect under 
 observation, for we can gently press down the cover 
 until the insect is trapped and held secure between the 
 two glasses. 
 
 In observing an unprepared section of some fruit or 
 plant it is best to place it on a glass slide and cover it 
 with a drop of water, placing over it one of the thin 
 cover-glasses used for the purpose. By doing so not only 
 are particles of dust and dirt kept from the object, but 
 
PLATE VIII 
 
 
DISSECTING. 37 
 
 also the microscope may be tilted to any angle re- 
 quired, without fear that the object will fall off the stage. 
 
 V. 
 
 Although requiring patience and perseverance, the 
 dissecting or cutting up of insects and small animals 
 reveals many interesting objects and teaches us much 
 about their internal structure. One of the first things 
 to remember is, never to kill any creature unless you 
 really intend to learn something from examination of 
 its body. Secondly, always make quite sure that your 
 victim is dead before you start operating. 
 
 Dissecting under the compound microscope is at first 
 somewhat difficult. Not only do we feel awkward in 
 dealing with minute objects such as the hairs or scales 
 of insects, but also the objects become inverted, and 
 changed from left to right when seen in the microscope. 
 After a little practice, however, this state of affairs 
 becomes quite natural. Dissections should be carried 
 out under water, contained in a shallow trough. A 
 porcelain dish, such as is used for mixing water-colour 
 paints, or a watch-glass will do admirably for the pur- 
 pose. More delicate work may be accomplished in a 
 drop of water placed on a glass slide. 
 
 If we are anxious to learn what is inside an insect, 
 such as a bee or a fly, and the object is too large to be 
 dissected under even the lowest power of our microscope, 
 we may carry out the first part of the operation under a 
 simple magnifying glass. This should be firmly mounted 
 in a temporary stand, thus leaving both hands free for 
 operating. Having cut the insect open, extracted its 
 
38 THE MICROSCOPE. 
 
 internal organs and separated the limbs from its body, 
 we may proceed to examine them with the higher powered 
 microscope. 
 
 When insects have been killed for any length of time 
 their bodies become hard and brittle. They may be 
 softened by steeping them in a dilute solution of caustic 
 potash (liquor potass a), which may be obtained from a 
 chemist. 
 
 Instruments for dissecting may be purchased from 
 almost any firm of opticians, but the 
 simple ones required by the beginner 
 may be easily made at home, with 
 the exception of a pair of tweezers 
 which must be purchased (Fig. 18). 
 It is only waste of money for us to 
 purchase an expensive outfit of " tools " 
 before we see if we like dissecting work ; 
 because, as I have already mentioned, it 
 requires a good deal of patience and per- 
 severance. 
 
 For simple dissections we shall require 
 three dipping-tubes, somewhat similar to 
 those used in collecting objects (Fig. 19). 
 These may be made by obtaining some glass 
 tubing from a chemist. The first is simply 
 a length of about six inches, and may be 
 cut to size by filing a groove around the 
 tubing with a nail file. On giving the tubing 
 a sharp blow the required length will break 
 off. The second is made by heating the centre of a length 
 of tubing until it becomes soft. Take a firm hold of 
 
 \ 
 
 FIG. 19. 
 Glass tubes. 
 
DISSECTING INSTRUMENTS. 39 
 
 both ends and draw them out, allow the tube to cool, 
 file around the centre as in the previous case, and break 
 off. The third tube is made similarly to the second, 
 except that while hot, and after being drawn out, the 
 tube is bent to the required curvature. 
 
 Three needles should now be mounted in wooden 
 handles ordinary sewing needles pushed 
 into wooden penholders will do very well 
 (Fig. 20). The first should be left straight, 
 the second bent in a flame to a right angle, 
 the third curved to a similar shape to the 
 third dipping -tube. The joint where the 
 needles enter the handle may be bound 
 round with thread, and the whole varnished 
 over with shellac. 
 
 With this modest equipment, a pair of 
 sharp nail scissors, and a good penknife . 
 sharpened and ground to a razor-like edge, Dissecting 
 we can find sufficient work before us to 
 employ all the spare hours of many a winter's night. 
 
CHAPTER IV. 
 MICROSCOPIC PLANTS. 
 
 I. 
 
 IN almost any pond will be seen an abundant supply 
 of minute life, both plants and animals. In some 
 ponds, especially those in which the water is green and 
 stagnant, life abounds in every drop of water. Each 
 object examined under the microscope will afford us a 
 fund of knowledge. Even from the lowliest forms of 
 pond life we can learn a great deal which will help us 
 when we come to study the higher and more complicated 
 forms of vegetable and animal life. 
 
 Microscopic objects may be found either floating on 
 the surface or swimming in the water, while a large 
 number are to be found only at the bottom of the pond, 
 embedded in the sand or mud. We have already seen 
 how to collect such objects, and we will assume that we 
 have paid a visit to a suitable pond and returned with 
 a good " bag " or rather, in this case, a full bottle. 
 After allowing the water to stand a short time and the 
 contents to settle, we may commence to examine it, 
 taking up a little at a time in the pipette or dipping-tube 
 already described and placing it in the live box. An 
 
 40 
 
PLATE IX 
 
 ^--colour clrawing by] 
 
 A swarm of Euglena viridis near the surface 
 of a stagnant pond 
 
 10. Fisher-Jones 
 
DESMIDS. 41 
 
 easy way to quickly examine a quantity of water is to 
 employ one of the small syringes used in filling fountain 
 pens. 
 
 One of the first things we are sure to see are bright 
 green objects of various shapes. These are called desmids, 
 and they are well-known microscopic plants. When 
 plants are mentioned some people at once think of the 
 flowering plants in our gardens, or the plants which we 
 have in pots and vases in our homes. These kinds of 
 plants form only a small proportion of the plant life 
 of the world, however, for there are many other speci- 
 mens of plants of the existence of which most people are 
 quite ignorant. Some of these plants are to be found 
 in the most unlikely places. Would you ever think, 
 for instance, of expecting to find interesting forms of 
 plant life in a rotting wooden fence or an old tree trunk ? 
 Yet it is probably no exaggeration to say that in such 
 a place it is possible to find more varieties of microscopic 
 plant life than there are examples of the higher orders 
 in the Botanical Gardens at Kew. 
 
 II. 
 
 The Desmids are an extensive family of plants 
 composed only of a single cell. They are placed at 
 the bottom rung of the ladder of botanical classifica- 
 tion. Desmids live in fresh water ; in some ponds they 
 are so numerous as to cause the water to assume a decided 
 greenish colour. 
 
 In addition to presenting a very beautiful appearance 
 the presence of this bright green colour is useful to the 
 microscopist, for it enables the desmids to be rapidly 
 
 (2,084) 6 
 
42 THE MICROSCOPE. 
 
 distinguished from most other one-celled plants. The 
 green colouring matter in desmids, and in all other plants 
 also, is called chlorophyll. This name comes from the 
 Greek word chloros, meaning "green," and by the pres- 
 ence of chlorophyll members of the vegetable kingdom 
 are easily distinguished. How important this aid is we 
 shall see later, for it is sometimes almost impossible to 
 say whether a minute object is a vegetable or an animal 
 from its shape alone. 
 
 Desmids are found in all manner of shapes, and there 
 are so many varieties of them that they have been 
 divided into groups to help in their identification. They 
 present so many interesting problems, indeed, that books 
 have been written on them alone. 
 
 Some desmids are more or less irregular in form, like 
 Euastrum, which consists of two main portions of a 
 bright green colour, joined together by a narrow waist- 
 like piece. Its edges are notched and indented, and 
 it is covered with dark green spots (d, Plate II.). An- 
 other variety is the crescent-shaped Closterium, of which 
 there are several species, although all are of the same 
 general shape (b, Plate II.). Sometimes the green cells 
 are surrounded by a transparent substance like gelatine ; 
 occasionally this is so indistinct as to be almost invisible. 
 
 Often several of these minute plants are found joined 
 together, forming what looks something like part of a 
 bamboo cane with notched edges (c, Plate II.). This 
 type is called Desmidium, and from it the desmids take 
 their name. The variety called Scenedesmus also consists 
 of several cells joined together, the last two cells having 
 hair-like projections (/, Plate II.). Another desmid of 
 
DESMIDS. 43 
 
 a somewhat similar kind is Pediastrum ; here the cells 
 unite and form a rounded mass. Each cell has pro- 
 jections, and the whole colony presents a beautiful 
 appearance (e, Plate II.). 
 
 A peculiar feature of the desmids is their constant 
 movement through the water in which they live. How 
 this movement is accomplished is as yet undecided. 
 It may be that each cell has a large number of very 
 fine hair-like organs which, like the oars of a boat, row 
 the plant along, as is known in the case of some other 
 minute plants which we shall consider later. Or perhaps 
 the explanation is to be found in the fact that the cells 
 give off some sort of exudation or discharge, and that 
 this act causes them to move through the water. 
 
 When a desmid is fully grown it breaks up into two 
 portions, and these commence to grow ; later they them- 
 selves divide. It is in this way that these minute plants 
 multiply. They illustrate for us the simplest mode of 
 reproduction in Nature, that of cell-division. Often we 
 may watch this division taking place, or see different 
 desmids in various stages of breaking up. 
 
 Take, for instance, Closterium, several specimens of 
 which we are almost sure to find in a bottleful of water 
 from some pond. Here is a young plant exhibiting 
 a peculiar marking like a faint belt across its centre 
 (a, Fig. 21). As the tiny desmid grows this marking 
 becomes more and more pronounced and soon becomes 
 a notch, or " waist," so that it would seem almost as 
 though some one had tied an invisible rope around the 
 centre and that this rope is being drawn tighter and 
 tighter as time goes on (b, Fig. 21). The waist becomes 
 
44 
 
 THE MICROSCOPE. 
 
 narrower and narrower until at last the plant divides 
 completely in half and we find we have two new speci- 
 
 FIG. 21. Closterium, a microscopic plant, (a) Natural view. 
 (6) Dividing, (c) Two plants. 
 
 mens of Closterium (c, Fig. 21). If we examine the two 
 halves carefully we can already see signs of the formation 
 of another waist-belt, ready for the time when the two 
 halves will themselves again divide. 
 
 III. 
 
 Another family of one-celled plants is the Diatoms. 
 They are even more numerous and more common than 
 the desmids, which they resemble in many ways. There 
 is, however, one great difference. When a desmid dies 
 its substance becomes decomposed and perishes. On 
 the other hand, a diatom is almost indestructible, for it 
 is surrounded by a hard, flinty shell. This shell, or 
 outer skeleton as it is sometimes called, is constructed 
 of silica, extracted by the diatom from the water in 
 which it lives. Thus, though we are able only to examine 
 
PLATE X 
 
 From a water-colour drawing byl [G. Fisher-J< 
 
 i. Mcliccrta ringens. 2. Rotifer vulgaris. 3. Parajticpciuin a?irelia. 
 
 4. A very young Mclicerta which lias been placed a second 
 
 time in water coloured by carmine. 
 
DIATOMS. 45 
 
 living or very recently dead desmids, it is possible to 
 examine the shell-cases of diatoms, the owners of which 
 have been dead some time. In fact, so successfully do 
 they resist the ravages of time and of the elements that 
 the skeletons of diatoms which lived thousands of years 
 ago are still perfectly preserved in some of the rocks of 
 the Earth. 
 
 The first known forms of diatoms were discovered 
 towards the close of the eighteenth century by Miiller. 
 In 1824 Agardh published his book, Sy sterna algarum, 
 describing nine varieties of diatoms. Now over 10,000 
 species are known, and about 1,200 of these are found in 
 the fresh waters and around the coasts of Great Britain 
 and Ireland. 
 
 Diatoms are found everywhere in all the known waters 
 of the Earth. We may safely say that, wherever there 
 is moisture and light, there too will diatoms be found 
 in ditches, ponds, and in mountain tarns ; on moist rocks, 
 and as a deposit of brownish mud in streams and pools. 
 They live in countless millions in our oceans, and in 
 some estuaries they are so abundant that they play an 
 important part in diminishing the depths of channels. 
 In some cases they have been known even to block up 
 harbours. 
 
 In the microscope a diatom looks like a fragment of a 
 beautifully engraved diamond, and no one can see these 
 objects without an expression of wonder at their delicate 
 beauty. Diatoms are of all imaginable shapes and, 
 unlike the bright green desmids, are of a golden-brown 
 colour. Some are disc-shaped, like Craspedodiscus, 
 which is beautifully marked (a, Plate III.). Others 
 
46 THE MICROSCOPE. 
 
 resemble squares joined together, like Melosira. Some, 
 again, are triangular, like Triceratium (b, Plate IV.). 
 Perhaps the commonest variety is the oval or boat- 
 shaped diatom, of which Pinnularia and Navicula are 
 examples (Plate V.). 
 
 Diatoms are of all sizes, a " giant " measuring as much 
 as -g^ inch in length ; but the majority are less than TTr V^ 
 inch in size. Their shells are often of most exquisite 
 design, and are covered with delicate markings, and minute 
 holes or pores. The fine lines of the diatoms will illustrate 
 for us the power of a microscope. If we were to draw two 
 lines very carefully only T -^ inch apart, the space between 
 them would only just be visible as a white line. To 
 represent the lines on some diatoms we should have to 
 divide this space of T ^ inch into over 500 spaces. 
 The lines on some diatoms are even finer, and to repre- 
 sent them correctly the T ^ inch space would require 
 to be divided into over 900 spaces ! These lines are often 
 used as objects with which to test the power and quality 
 of microscopic objectives. 
 
 The markings on diatom shells have been the sub- 
 ject of endless discussion. The most expert workers and 
 the finest lenses have been employed in the endeavour 
 to find out what exactly is the meaning of the numerous 
 lines and pores with which diatoms are covered. So 
 fascinating is their study, indeed, that some scientists 
 have been influenced to put aside all other microscopical 
 work in order that the whole of their time might be de- 
 voted to diatoms. Because of this, and because these 
 scientists so often talk and write about these beauti- 
 ful little creatures, they have sometimes been called 
 
DIATOMS. 47 
 
 " diatomaniacs " by rude and ignorant people who do 
 not understand these things. 
 
 Diatoms derive their name from two Greek words, 
 dia, " across," and tome, " cut," because each shell is cut 
 or divided into two parts, called the frustules. One of 
 these frustules overlaps the other, fitting on it like the lid 
 of a pill-box. 
 
 Like the desmids, diatoms reproduce themselves by 
 simple cell-division, a single diatom dividing into two. 
 So quickly can they multiply in this way that it has 
 been calculated over 1,000,000,000 diatoms may be 
 produced from a single parent in a month, under favour- 
 able conditions. 
 
 When a diatom dies its shell sinks through the water 
 and falls to the bottom of the pond or ocean. So numer- 
 ous do these shell-cases or skeletons become that they 
 form a kind of mud or sediment, called diatomaceous 
 ooze. Deep-sea soundings have shown that some of 
 these deposits are of very great extent. Off the shores 
 of Victoria Land, for instance, in 70 south latitude, at 
 a depth of between 200 and 400 feet, is a deposit of mud. 
 This extends not less than 400 miles in length and 120 
 miles in breadth, and is chiefly composed of the shell- 
 cases of diatoms. In the course of ages thousands 
 upon thousands of years, perhaps this mud may be 
 hardened into a solid rock, which may be lifted above 
 the ocean by movement of the Earth's crust. This is 
 actually what has happened in the case of some rocks 
 which are found to-day high and dry above the ocean in 
 many parts of the world. 
 
 In Bohemia, rocks composed of the fossil shells of 
 
48 THE MICROSCOPE. 
 
 diatoms which lived years ago are found in beds which 
 are fourteen feet thick. More wonderful still are the 
 deposits at Richmond, Virginia, U.S.A. They are re- 
 markable both on account of their extent and because 
 of the number and beauty of the specimens of diatoms 
 they contain. Here the skeletons of long-dead diatoms 
 form a bed extending over many miles, and at some 
 places the rock is at least forty feet in thickness. It is 
 impossible for us to imagine the number of minute 
 diatom shells required to form a deposit so great. We 
 may obtain some idea of the immense numbers from 
 particulars of a block of diatom deposit to be seen in 
 the botanical section of the British Museum. This 
 block measures only two cubic feet in bulk, and was 
 obtained from a fresh-water lake in Australia. It is 
 estimated that it contains more than twelve billions 
 of fossil diatoms ! 
 
 IV. 
 
 One of the most beautiful objects found in pond water 
 is Volvox globator. Through the microscope Volvox 
 resembles a beautiful lace-like tracery, more delicate 
 than a spider's web (see Frontispiece). This covering 
 is studded with minute green spots, each of which ter- 
 minates in two long cilia, or gossamer-like hairs. It is 
 believed that it is by the aid of these cilia that Volvox 
 is able to swim, for they are constantly in movement, 
 thrashing the water. Healthy specimens are always 
 in motion, gliding gracefully along, and resembling at 
 tunes minute revolving worlds. It was this extraor- 
 dinary power of moving from place to place which at 
 
PLATE XI 
 
VOLVOX. 49 
 
 one time led microscopists to think that Volvox was an 
 animal, and controversy raged over the question for a 
 long time. Volvox was first classified in the animal 
 kingdom, but at last it was definitely described as being 
 a true plant. 
 
 The green spots, already referred to, give Volvox the 
 appearance of a minute knitted ball of orange-tinted 
 green silk, and very exquisite it looks. It is possible to 
 see through the outer lace-like sphere, and often smaller 
 green globes are visible within the network. These tiny 
 globes are really young Volvoces. Sometimes they are 
 six or eight in number, but in some cases as many as 
 twenty have been counted. Occasionally even a third 
 generation may be seen inside the young Volvoces them- 
 selves. 
 
 As time goes on, the young Volvoces develop until 
 there comes a day when they are sufficiently grown to 
 shift for themselves. They break through the sphere 
 in which they were born, the sides of their mother open- 
 ing to allow them to glide through. At first they are 
 attached to their parent by long filaments, but they soon 
 tire of being tied by these " apron-strings." They 
 break away, commence life on their own account, and 
 soon grow to the size of the parent Volvox. 
 
 Volvox is not a single cell, like the desmids and diatoms, 
 although it is included in the same botanical classifica- 
 tion. It really belongs to a higher organization, being 
 a colony or assemblage of minute cells, just as a daisy 
 is a composite flower. It is to be found in those clear, 
 fresh-water pools which are open to sunlight, for like 
 most plants it is fond of sunshine. The water of some 
 
 (2,084) 7 
 
50 THE MICROSCOPE. 
 
 ponds is so full of Volvoces that when held up to the 
 light in a glass jar it seems to be of a semi-transparent 
 green colour. 
 
 Volvo x measures from about ^ to ^ mc ^ i* 1 s i ze - 
 The larger specimens may be seen easily with the naked 
 eye, looking like minute specks of green matter. Be- 
 cause of its incessant movement, already mentioned, 
 Volvox is often a difficult object to photograph or draw 
 correctly in detail (Plate VIII.). 
 
 V. 
 
 In pond water we often find, in addition to desmids and 
 diatoms, several other forms of vegetable life. Some- 
 times we may come across long, green filaments of a 
 variety of forms. These are the fronds of conferva, and 
 they are composed of a number of cells growing together 
 and looking somewhat like a bamboo cane. As in the 
 case of the desmids and other plants, they too owe their 
 green colour to the chlorophyll they contain. In some 
 species, as in Zygnema, the chlorophyll is found formed 
 in spirals (Fig. 22). 
 
 Often two specimens of these plants may be seen to 
 join or fuse together and the contents of one are trans- 
 ferred to the other, bead-like objects called spores 
 being formed (b, Fig. 22). Spores are the first stage in the 
 life-history of the lower plants such as seaweed, fungi, 
 mosses, and ferns. Just as flowering plants grow from 
 seeds, so do the lower plants spring from spores. 
 Perhaps the most familiar spores are the masses of 
 brown powder on the under-side of the frond of a fern. 
 Spores are very minute, and when ripe are scattered by 
 
ZOOSPORES. 51 
 
 the wind or water. The spores of some fungi and sea- 
 weeds disperse themselves by being able to swim in the 
 water, and afford examples of free movement in the 
 plant world. Because of this resemblance to animals 
 
 if 
 
 a is c a 
 
 FIG. 22. Zygnema, a microscopic plant, (a) Showing the chlorophyll 
 spirals. (6) Formation of spores, (c) Zoospores leaving the plant. 
 (d) A zoospore, showing cilia. 
 
 their being able to move about these spores are called 
 zoospores. 
 
 In the case of Zygnema, which we have already men- 
 tioned, zoospores are sometimes formed instead of the 
 ordinary spores. When this occurs, the contents of the 
 cells draw together and form the zoospores (c, Fig. 22), 
 which then break away from the parent cell and move 
 rapidly about through the water in all directions, by 
 means of cilia, or fine hair-like appendages. 
 
 Occasionally zoospores gather together and move 
 rapidly about in a sphere. A common example of this 
 
52 THE MICROSCOPE. 
 
 class of object is Pandorina Morum (Fig. 23), each spore 
 
 in the colony of which possesses two cilia. 
 
 Sometimes in our examination of pond 
 water we come across a queer-looking 
 object, called Euglena viridis (Plate IX.). 
 In some ponds they exist in such large 
 
 FIG. 23. Pan- numbers as to make the water look like 
 
 donna Morum. _ t , J . . 
 
 pea-soup. The appearance of this minute 
 plant in the microscope is remarkable, for it resembles 
 nothing so much as a sole or similar fish. It is of a 
 green colour, with a red spot, which we may imagine 
 to be its eye, at one end and a kind of drawn-out tail 
 at the other. Its appearance is deceptive, and it may 
 easily be mistaken for a member of the animal kingdom, 
 although it is really a plant with extraordinary powers 
 of locomotion, like Volvox or Pandorina Morum. 
 
PLATE XII 
 
 From a w&'er-cr>lnnr drawing by] 
 
 [G. Fisher-Jones 
 
 Stephanoceros Eichorni! 
 
XJ 
 
CHAPTER V. 
 MICROSCOPIC ANIMALS. 
 
 I. 
 
 IF I were to ask if you could always distinguish 
 between an animal and a vegetable, you would 
 possibly think that I did not give you credit for possess- 
 ing much intelligence. It is true that when we have in 
 mind some of the more highly developed members of 
 either kingdom, say a cat and a cabbage, the difference 
 is very pronounced. But among the more lowly members 
 of these kingdoms, members which interest us more at 
 present because they are to be seen in detail only with 
 a microscope, the difference is not so apparent. For 
 instance, could you tell me without referring to books 
 whether a sponge is of an animal or a vegetable nature ? 
 As a matter of fact, it represents a colony of animals 
 which are more highly developed than many animals 
 having bodies with heads, mouths, and tails, and which 
 are not as the sponge generally is fastened to a 
 re * but swim freely about in the waters of the ocean. 
 Appear; ices are deceptive, however, for many vegetable 
 organisms seem to bear a closer resemblance to animals 
 than does a sponge. 
 
34 THE MICROSCOPE. 
 
 The problem of deciding whether certain microscopic 
 organisms belong to the animal or the vegetable king- 
 dom has occupied the attention of some of our most 
 distinguished scientists, and given rise to endless discus- 
 sions. At one time it was thought that we could be 
 guided in deciding if an organism was an animal or a 
 vegetable by the green colouring matter called chloro- 
 phyll, the presence of which was believed to indicate 
 that an organism was certainly a true plant. Distinc- 
 tion by these means became difficult, however, when 
 later on it was found that chlorophyll existed in some 
 of the minute forms of animal life, called animalcules. 
 On the other hand, it was found that the substance 
 called cellulose, of which the walls of plant cells are 
 composed, enters into the composition of certain 
 animalcules found in the sea. 
 
 Nor are we helped in distinguishing between plants 
 and animals according to whether or not the organism 
 has powers of locomotion. We generally imagine an 
 animal as being able to move from place to place, and 
 a plant as being permanently stationary. As we have 
 already seen, however, the plant Volvox is provided 
 with organs which enable it to move about. On the 
 other hand, there are forms of animals which are always 
 fixed to one place. To add to the uncertainty, some 
 organisms seem almost to have an animal form of exist- 
 ence at one period of their life-history, and a vegetable 
 form at another. A well-known instance of this is the 
 yellow fungus which is found in tan-pits, called jEthalium, 
 or " flowers of tan." Not only does it move about from 
 place to place, but it also actually feeds upon solids. 
 
SIMPLE PLANTS AND ANIMALS. 55 
 
 One of the most certain methods of distinguishing 
 between one-celled plants and one-celled animals is the 
 difference in the method of obtaining food or nutrition, 
 as it is called. A green plant is able to live independently 
 of other organisms, by the help of light, heat, and mois- 
 ture. It builds up its substance from simple gases con- 
 tained in the air and from solutions of inorganic salts, 
 found in the soil or water. On the other hand, an animal 
 can live practically independently of sunlight, but it 
 cannot exist apart from other living organisms, for it 
 depends upon them for its sustenance. It is unable to 
 build up its structure from simple chemical constituents, 
 as a plant does, but must be supplied with ready-made 
 proteids. By remembering these facts we are some- 
 times able to say to which kingdom some microscopic 
 form of life belongs, when otherwise we might have to 
 admit a doubt. 
 
 From what I have just said you will easily understand 
 that it has become very clear that the distinction be- 
 tween some of the simplest forms of plant and animal 
 life is occasionally so obscure and indefinite that it does 
 seem as though no definite dividing line can be drawn 
 between the two kingdoms. It seems probable, indeed, 
 that the two kingdoms do actually merge into each other 
 by imperceptible degrees. 
 
 II. 
 
 Wherever we find one-celled plants we may be almost 
 certain to find also animals to feed upon them. Just as 
 there are one-celled plants at the bottom of the ladder 
 of botanical classification, so, too, there are one-celled 
 
56 THE MICROSCOPE. 
 
 animals which occupy a similar position in the classifica- 
 tion of their kingdom. They belong to a class called 
 the Protozoa, from the Greek word proton, " first," and 
 zoon, " living thing." They are among the lowest forms 
 of animal life. Each is composed of a single cell of 
 living matter, a minute speck of jelly-like substance, 
 without limbs of any sort. Each cell is complete in 
 
 Fie. 24. Amoeba, (a) and (c) Showing nuclei, vacuoles and 
 pseudopodia. (&) Formation of two amoeba?. 
 
 itself, however, and can move, feed, breathe, and re- 
 produce others of its kind. 
 
 One of the best known is the Amaba, found both in 
 fresh and in salt water, but more often in the sediment 
 of ponds and rivers (Fig. 24). Amoeba looks like a 
 speck of jelly, for it is almost transparent. Sometimes 
 it seems to be merged in the water in which it floats, so 
 that it is difficult to say where the little creature begins 
 or ends. The animalcule may be actually under the 
 microscope, and yet the observer may not be aware of 
 
PLATE XIII 
 
 (a) 
 
 From photo-micrographs by] 
 
 (b) 
 
 [Messrs. Path6 Fr6res 
 
 (C) 
 
 DAPHNIA PULEX, (a) female, (b) male ; AND (c) CYCLOPS WITH YOUNG 
 HATCHING OUT 
 
AMCEBA. 57 
 
 it. If the insignificant speck be watched, however, it 
 will be found to move about and constantly change in 
 appearance, assuming some of the most grotesque forms 
 and fantastic shapes. These changes have become so 
 well known that when masses of cells of higher animals 
 exhibit similar variations of form they are called amce- 
 boids. Among the amceboids are the leucocytes, or white 
 corpuscles of the human blood. 
 
 It is because the Amoeba changes its shape so often and 
 assumes so many varieties of form that it was named 
 Proteus animalcule by Rozel von Rosenhof, who dis- 
 covered it in 1755. In Greek mythology, Proteus 
 was an " old man of the sea," who looked after the seal 
 flocks of Neptune. He had a great reputation as a 
 prophet, and possessed the gift of endless transformation, 
 adopting all manner of shapes and disguises in order to 
 escape from those inquiring people who wished to make 
 him prophesy for them. The name Proteus animalcule 
 was changed to Amibe by Bury St. Vincent ; and the 
 present name, Amceba, is the corresponding name in 
 Greek, and means " change." 
 
 Towards the centre of the Amceba is a nucleus, filled 
 with granular particles, and often showing one or more 
 bubble-like objects, called the vacuoles. Although this 
 nucleus does not, as a rule, alter in appearance, it moves 
 with every change of shape in the Amceba (c, Fig. 24). 
 Amceba reproduces itself by division, one cell dividing 
 into two (b, Fig. 24). Before this division takes place, 
 however, the nucleus splits up into two portions, each 
 ot which contains half the parent nucleus. In some 
 cases it takes only fifteen minutes for this to be accom- 
 
 (2,084) 8 
 
58 THE MICROSCOPE. 
 
 plished, and it is thus possible to watch the entire process 
 in the microscope. 
 
 Amcebce move about in a curious way, for they are not 
 provided with limbs, and have therefore to press them- 
 selves along. This they do by putting forth pseudopodia, 
 a word derived from the Greek pseudos, " false," and 
 pous, " foot." A protrusion, like a minute finger, is 
 first pushed out from some part of the body of the 
 Amoeba. Substance from the body is then transferred 
 to it. As soon as the transfer is completed, another 
 protrusion is put out, and the Amoeba is thus able to 
 draw its body forward or backward, moving in any 
 direction. 
 
 As it moves thus from place to place the tiny crea- 
 ture picks up its food, encountering small particles of 
 vegetable matter, or occasionally a diatom. These enter 
 through any part of its body and mix with its sub- 
 stance (a, Fig. 24). 
 
 Amoeba may rightly be counted among our most 
 wonderful animals, for, as Professor Huxley has said, it 
 walks without legs, eats without a mouth, and digests 
 without a stomach ! 
 
 III. 
 
 Some animalcules exist in many kinds of vegetable 
 infusions, and are therefore called infusory animalcules. 
 The great microscopist, Ehrenberg, divided them all 
 into two kinds : Poly gastric (" many-stomached ") and 
 Rotifer ous. 
 
 Of the Polygastrica a typical example is the beautiful 
 Paramcecium Aurelia, which moves through the water 
 
PARAMOECIUM. 59 
 
 in constant search for its prey (3, Plate X.). It is 
 strange that this magnificent animalcule should be 
 found in the dirtiest and filthiest of ponds, but it is a 
 fact that it loves best the kind of pond which is a recep- 
 tacle for the bodies of dead cats and dogs. Here it does 
 great work in clearing away the filth and refuse, and so 
 prevents it destroying the life of higher animals and 
 human beings. Paramcecium is of an oblong shape and 
 covered all over with cilia. It is very active indeed, 
 darting rapidly backward and forward, here and there, 
 or suddenly turning round and, by a quick move- 
 ment, changing direction altogether. In its inside we 
 can see several spots, and an interesting experiment 
 may be performed. If we mix a little colouring matter, 
 say carmine or indigo, with the water in which Para- 
 mcecium is confined, we shall soon see that the spots 
 in its inside become similarly coloured. This is due 
 to the animalcule taking in the coloured water, and 
 its inside becoming stained with it. From this" experi- 
 ment Ehrenberg came to the conclusion that the spots 
 were stomachs; and as similar spots are very common 
 amongst these animalcules, that is the reason he called 
 the species " the many-stomached." It is now thought, 
 however, that these spots are not true stomachs, but 
 spaces, or vacuoles, in the animalcule's body. 
 
 The second kind of infusory animalcule, the Rotifera, 
 are so called because with the microscope they appear 
 to have little wheels on the upper part of their bodies. 
 Their name comes from the Latin rota, " a wheel," and 
 few, " I bear." For this reason they are sometimes 
 called " wheel animalcules." The so-called wheels are 
 
60 THE MICROSCOPE. 
 
 really two extended portions of the animalcule's body, 
 the edges of which are covered with a large number of 
 cilia. These cilia are moving incessantly, and thus 
 cause the impression of a tiny wheel rotating on an axis. 
 
 One of the commonest wheel animalcules is Rotifer 
 vulgaris, found on the leaves and stems of almost any 
 common water plant (2, Plate X.). A more interest- 
 ing member of the family is Melicerta, the brick-building 
 Rotifer (i, Plate X.). It is also found on water 
 plants, and to the unaided eye looks like a little twig 
 or stump about ^j- inch in length, fixed to the plant 
 stem by one end of its body. In the microscope, the 
 little stump is seen to consist of numbers of rounded 
 pellets like minute bricks, and placed in regular rows 
 one above the other. As we watch the little tube of 
 bricks, we are sure to see before very long the head of 
 Melicerta peep cautiously above the edge. Suddenly, 
 as though assured that the coast is clear, Melicerta 
 fearlessly thrusts out its head, which then expands and 
 looks not unlike a minute silver pansy. The edges of 
 the petal-like lobes of the head are surrounded with 
 innumerable cilia, always in rhythmical motion. When 
 watching it under the microscope, it is most difficult 
 to believe that the lobes are not actually two minute 
 toothed cog-wheels, rapidly rotating. 
 
 On further study, Melicerta is seen to be composed of 
 transparent, fleshy matter with many folds. At one 
 side is a pair of hooked spines, while at the other are two 
 slender projections. Below the four petal-like lobes is 
 a kind of chin, immediately beneath which is the ap- 
 paratus with which Melicerta makes the bricks for its 
 
PLATE XIV 
 
 from a photo-micrograph by] 
 
 (a) 
 
 [A. E. Smith 
 
 From phucoimcrographs by] 
 
 [E. Cuzner, F.K.M.S. 
 
 (0 
 
 SECTIONS OF PLANTS 
 (a) Rattan cane. (b) Stem of Ruscus. ( c ) Marram grass 
 
THE BRICK-MAKING ROTIFER. 61 
 
 " house." The material for the bricks consists of 
 matter gathered from the surrounding water and brought 
 within reach of the brick-making apparatus in currents 
 set up in the water by the vibrating cilia. The particles 
 so gathered may be seen whirling around the petal-like 
 lobes in the currents they set up. They are passed 
 down narrow grooves on each side of the chin, already 
 referred to, until they reach the brick-making apparatus. 
 This is in the form of a minute hemispherical cup, which 
 acts as both mixing chamber and mould. The particles 
 are here welded together and form a tiny brick, which 
 is then placed on the rim of the tower by Melicerta 
 bending forward its head and depositing the brick there. 
 Brick after brick is thus placed in position, and the 
 tower rapidly increases in height. 
 
 An interesting and beautiful experiment may be 
 performed with Melicerta by adding to the water in 
 which it is working a little carmine colouring matter. 
 This is taken in with the particles, and the resulting 
 brick is of a red colour. The colouring matter in the 
 water may be changed at will, and it is thus possible 
 to cause Melicerta to build a tower of different coloured 
 bands, the width of each band depending on the length 
 of time during which Melicerta is allowed to work in the 
 water containing any particular colouring (4, Plate X.). 
 
 IV. 
 
 If some hay be steeped in a glass of water for a few 
 days, a number of beautiful little animalcules, called 
 Vorticellce, will be almost certain to appear. Some are 
 large enough to be seen with the unaided eye, but others 
 
62 THE MICROSCOPE. 
 
 can only be examined with the microscope. You may 
 easily distinguish Vorticella, because they have tiny, 
 cup-shaped bodies on a long stalk, and look more like a 
 cluster of beautiful microscopic lilies-of-the-valley than 
 a group of minute animals. If the slide on which they 
 are placed be jarred, or if the little creatures be otherwise 
 disturbed, the stalk contracts into a spiral, drawing the 
 cup-shaped body down to its base (4, Plate XL). 
 
 Vorticellce draw their food into their mouths by setting 
 up currents in the water. These currents are caused by 
 the constant movements of the cilia, with which the 
 mouth of the tiny cup is surrounded. The currents of 
 water pass into the body of the animalcule by means of 
 a minute aperture, and pass out again by a similar but 
 different aperture. Many interesting changes may be 
 noticed in the Vorticella, which sometimes become de- 
 tached from their stalks, the cup-like body rolling about 
 free in the water with contracted mouth (7, Plate XL). 
 
 Another common and well-known infusory animalcule 
 is Stentor, the " Trumpet-animalcule," found attached to 
 the under-side of duckweed in fresh water (i, Plate XL). 
 It is generally of a brilliant green colour, and is com- 
 paratively large. When fully extended it may measure ^ 
 inch in length. In appearance it resembles the mouth of 
 a cornet, or bugle, and is a very beautiful object. Its 
 wide, trumpet-like mouth is fringed with long cilia. It 
 reproduces by dividing into two. 
 
 V. 
 
 Another interesting Rotifer which, like Melicerta, is also 
 a tube-dweller, is Stephanoceros Eichwnii (Plate XII.)- 
 
STEPHANOCEROS. 63 
 
 It has a transparent tube, or body, resembling gelatine, 
 inside which may be seen differently coloured objects. 
 Some of these are the internal organs, and others, per- 
 haps, are animalcules which have been swallowed 
 and upon which Stephanoceros feeds. Occasionally 
 clusters of eggs may be seen, for these Rotifers multiply 
 in a similar way to Daphnias described in the next 
 chapter the eggs being hatched before leaving the body 
 of the parent. It is most interesting to watch the 
 development of the young Stephanoceros, which, from 
 the time of its birth to full growth, occupies from five 
 to ten days. 
 
 You will readily understand that Stephanoceros is an 
 exceedingly difficult object to draw, when I tell you that 
 most of the existing illustrations of it are incorrect. Mr. 
 Martin Duncan, F.R.M.S., searched the library of the 
 Zoological Society for illustrations for this book, and he 
 believes that no good illustration exists. Some years 
 ago Mr. Duncan succeeded in taking an instantaneous 
 photo-micrograph of it, however, and this photograph 
 he kindly placed at the disposal of my friend Mr. Fisher- 
 Jones, who has made the very beautiful drawing shown in 
 Plate X., the details of which may be taken as being 
 substantially correct. 
 
 The magnificent appearance of Stephanoceros is due 
 to the five curved arms which protrude above it, forming 
 a figure resembling a delicate arch or dome. These 
 curved arms may be likened to the tentacles of an 
 octopus, for with them Stephanoceros catches and retains 
 its prey. They are furnished with fifteen rows of short, 
 vibrating cilia, and may be withdrawn into the tube at 
 
64 THE MICROSCOPE. 
 
 will. This generally happens if the creature receives a 
 shock from the jarring of the microscope stage or the 
 plant-stem to which it clings. 
 
 Unfortunately, Stephanoceros is not very common. It 
 should be looked for on the under-surface of aquatic 
 plants, such as the water-lily. Specimens once having 
 been obtained may be kept alive in the aquarium, and 
 under favourable circumstances will thrive and multiply. 
 They should be kept in water obtained from the pond in 
 which they were found. 
 
PLATE XV 
 
 o 
 
 
 
 
 
 
 
 
 
 
 
 
 s 
 
CHAPTER VI. 
 DAPHNIA AND CYCLOPS. 
 
 I. 
 
 A LTHOUGH the subjects of this chapter are micro- 
 /Iscopic animals and therefore, strictly speaking, 
 should have been included in the previous chapter, I am 
 sure you will not mind me giving them a chapter to them- 
 selves, for they are sufficiently interesting to warrant it, 
 as I think you will agree after you have studied them. 
 If we have spent any length of time collecting desmids 
 and other similar objects at a pond, we cannot fail to 
 have noticed some of the comparatively large forms of 
 animal life there. I do not mean frogs and newts, but 
 the microscopic crabs, or water-fleas, and that curious 
 looking object called Cyclops, the one-eyed. 
 
 The celebrated Dr. Johnson once defined the word 
 " insect " as meaning " anything small and contempt- 
 ible," but this is by no means the definition of the word 
 to-day. Science has stepped in, and an insect is now more 
 definitely denned. At the first glance we might almost 
 assert that the water-flea (Fig. 25) is an insect, but it is 
 not truly so, for it does not conform to those characteristic 
 features by which insects are recognized. Although it 
 
 (2,084) 66 9 
 
66 THE MICROSCOPE. 
 
 may seem very similar in appearance to a flea, Daphnia 
 pulex, the water-flea, belongs to that class of animals 
 called Crustaceans. These have their soft bodies pro- 
 tected by an outer crust or shell, and the crab and the 
 lobster are larger specimens of the same order. There 
 
 itennae 
 
 Heart 
 
 Ovary 
 
 -Brood. Chamber 
 
 Maxillary 
 Gland 
 
 FIG. 25. Daphnia, the water-flea. 
 
 are many other members of this interesting family, 
 some of the members of the lower orders living only as 
 parasites. These are in many cases so different from the 
 higher members that they do not appear to bear any 
 resemblance to them. It is, nevertheless, a fact that 
 whether they live on land as do the centipedes and the 
 
THE WATER-FLEA. 67 
 
 multipedes or live in water as the water-flea and the 
 brine-shrimps all once belonged to the same original 
 stock. 
 
 Daphnia belongs to a sub-division of Crustacea with the 
 rather long name of Entomostracans, meaning shelled 
 insects. This name is likely to be confusing unless we 
 keep well before us the fact that these creatures are not 
 truly insects. The true flea is an insect having head, 
 thorax, and abdomen, but Daphnia has its head 
 encased in a shell and has no neck, so that its head 
 and thorax are not separate but run into one another. 
 The difference will be clearly seen by comparing to- 
 gether a and b, Plate XIIL, and Plate XXXIV. It 
 does not breathe through tracheae or breathing tubes, 
 but has numerous legs with gill-like appendages. 
 Because these leg-appendages are to Daphnia what 
 lungs are to us or gills to a fish this tiny water- 
 flea may be said to breathe through its toes ! Water- 
 fleas have an ancient line of ancestors, for they have 
 been traced back to the Coal Age that period of 
 the Earth's history during which our coal was formed. 
 In those far-off times water-fleas must have lived in 
 large numbers in the great standing pools of the coal 
 forests. 
 
 Daphnia has a body covered with an almost trans- 
 parent casing, like that of a shrimp. Although the name 
 of their sub-division means shelled insects, their covering 
 cannot be truly described as a shell. It is composed of 
 chitine (pronounced " ki-tin "), a name which comes 
 from a Greek word meaning " a tunic or outer dress." 
 Chitine is indeed a wonderful substance, for it is found 
 
68 THE MICROSCOPE. 
 
 in the insect world in an endless variety of forms and 
 shapes. The hard black bodies of beetles are composed 
 of it ; as are the downy wings of the butterfly ; the facets 
 of insects' eyes ; the tendons, legs, hair, membranes, and 
 many other parts of their bodies. 
 
 Through the transparent shell of the water-flea may be 
 seen the internal organs at work. They furnish a wonder- 
 fully interesting sight, including a curious organ which 
 pumps like a heart, and many canal-like veins and 
 arteries. If the specimen is a female it may be possible 
 to see also numerous eggs. If one has sufficient patience 
 these may be watched until they hatch out. 
 
 Unlike birds, which first lay and then hatch their eggs 
 in their nests, Daphnia both lays and hatches her eggs 
 inside her body, and for this a special receptacle is pro- 
 vided by Nature, called the brood-pouch. Here the 
 eggs remain until the little animals are hatched. Even 
 then they are not cast out into the waters to fend for 
 themselves, but are kept inside until they have grown 
 old enough to swim about and obtain an independent 
 livelihood. The brood-pouch is open to the surrounding 
 water, which enters through a slit in the shell, behind 
 the tail. The eggs are prevented from floating out before 
 their time by a slender tongue-like projection, fixed to the 
 back of the mother. When the young are sufficiently 
 grown to take their place in the world their mother has 
 only to depress her body a little more than ordinarily, and 
 the door is open, the young sliding from the brood-pouch 
 into the open water, like little ships just launched. As 
 is often the case with crustaceans, the young Daphnias 
 are quite unlike the parent. At first their body appears 
 
PLATE XVI 
 
 From photo-micrographs by] 
 
 SECTIONS OF MAHOGANY 
 (a) Longitudinal section. (b) Transverse section 
 
THE WATER-FLEA. 69 
 
 like the bowl of a miniature spoon, being transparent and 
 ending in two points carrying many bristle-like hairs. 
 The large dark eye can be clearly seen in front, and three 
 pairs of swimming feet, jointed and bristled, project 
 stiffly on either side. 
 
 The body of Daphnia is divided into five segments, 
 each of which has attached to it a pair of leaf-like swim- 
 ming feet. From the head there branch two pairs of 
 plumed appendages, which are the antennae. This 
 word comes from the Latin, and means " horns or 
 feelers." Daphnia has only one eye, which, looking 
 very bright and inquisitive, is really a single cluster of 
 ocelli, or insect eyes. 
 
 Daphnias may be found in large numbers in many pools 
 and ditches, coming to the surface in the mornings and 
 evenings or in cloudy weather, but seeking the depths of 
 the .water during the heat of the day. They swim by 
 taking short springs, darting through the water in a 
 succession of jerks, and this is another reason why they 
 have been called water-fleas. The males are usually 
 smaller than the females and certainly much more scarce, 
 being rarely met with before the end of summer. 
 
 Daphnias have many enemies, for they are tasty food 
 for several other inhabitants of the water in which they 
 live. It has been said on good authority that Loch 
 Leven trout owe their superior sweetness and richness 
 of flavour to their food, which consists of small shell- 
 fish and these Entomostracea. 
 
70 THE MICROSCOPE. 
 
 II. 
 
 Another interesting species of this same order is Cyclops 
 (Fig. 26). Cyclops is not at all particular as to whether 
 it lives in the clearest streams or in the muddiest and 
 most stagnant pools. It may be seen like an animated 
 atom it is not much more than T V 
 inch in length scuttling here and there 
 by a rapid succession of short leaps 
 among the water weeds. Cyclops has 
 only one eye, and that is how it gets its 
 name, for in classical mythology the 
 Cyclops were a wild race of giants led by 
 their one-eyed chief Polyphemus, whose 
 
 FIG. '^.-Cyclops. sin g le e y e WaS P laced ^ the middle f 
 
 his forehead. You have perhaps read the 
 story of how Ulysses was wrecked off the coast of Sicily, 
 and confined in a cave by Polyphemus, and of how he 
 contrived to escape by making the monster drunk and 
 burning out his single eye so large that it required five 
 heroes to " grind the pupil out " by a red-hot stake of 
 olive wood. 
 
 The eye of tiny Cyclops is placed similarly in the middle 
 of its forehead and glares like a minute ruby. It is so 
 small, however, that it cannot be touched with the point 
 of the finest needle ; it is nevertheless of very elaborate 
 construction, consisting of a number of simple eyes. 
 
 Cyclops has four pairs of swimming feet, and one 
 rudimentary pair. It also has two pairs of antenna. 
 Both feet and antenna are covered at each of their many 
 joints with tufts of feathery plumes. Its body is pear- 
 
CYCLOPS. 7i 
 
 shaped, broad in front and tapering behind, and is soft 
 and gelatinous. This body is divided into two distinct 
 parts, the thorax and abdomen. A jointed shell forms 
 a buckler which almost entirely encloses the head and 
 thorax. The abdomen is slender and might be mistaken 
 for the tiny creature's tail. The tail is at the extremity 
 of the abdomen, however, and has numerous plume- 
 like tufts. 
 
 On either side of the abdomen of the female is an oval 
 bag or sac, joined to the body by a very slender thread, 
 reminding one of John Gilpin, when, as the poem says, 
 
 " He hung a bottle on each side 
 To keep his balance true." 
 
 These oval bags are packed very full with clear and 
 transparent globules, which are the eggs. Not only are 
 the eggs thus exposed to the action of the water as neces- 
 sary, but they are also protected from being destroyed 
 by the enemies of Cyclops. The eggs are first developed 
 in the body of the mother, in a gland called the ovary. 
 When they are sufficiently matured they are transferred 
 into the oval sacs, through the exceedingly slender tube 
 connecting them to the body. They are then carried 
 about by the mother until they are hatched, when the 
 young Cyclops emerge in dozens (c, Plate XIII.). The 
 sacs, being no longer required, become detached and 
 decay. 
 
 Cyclops, while not so much of an acrobat as Daphnia, 
 is nevertheless a very active creature. It swims not only 
 with its legs and tail, but also strikes the water vigorously 
 with all its limbs and antenna. By rapidly moving 
 
72 THE MICROSCOPE. 
 
 its feet a whirlpool is created in the surrounding water 
 and minute animals of various kinds are thus brought 
 to its mouth. Cyclops is sometimes a cannibal, however, 
 for it has been known to devour even its own young 
 brought in by the whirlpool. 
 
 Both Daphnia and Cyclops belong to the Branchio- 
 poda, or " gill-footed " order. There are several other 
 interesting members which you may sometimes find in 
 ponds and streams. These include Artemia salina, 
 or the brine-shrimp, found in salt marshes and in reser- 
 voirs at places such as Lymington, where brine is de- 
 posited previous to boiling. It has peculiar movements, 
 for in addition to being able to swim in the correct 
 position it can also swim on its back or sides by means 
 of its tail, its feet being also in constant motion. 
 
PLATE XVTT 
 
 g?pB^- 
 
 From photo-micrographs by] (b) [A. Flatters 
 
 LONGITUDINAL SECTIONS OF WOOD 
 (a) Common pine. (b) Vascular bundle of Pteris Aquilina 
 
CHAPTER VII. 
 PLANT LIFE. 
 
 I. 
 
 NO objects for microscopic examination are more 
 easily obtained than plants. A few minutes in the 
 fields or meadows will enable us to gather material 
 sufficient for many hours' observations at home. The 
 study of plant life, or Botany, is a very extensive 
 one, and includes the study of vegetable cells and 
 tissues. We have already seen that all living things, 
 whether animals or plants, consist of cells, and that 
 some consist only of a single cell, like the desmids, while 
 others in a higher stage of development consist of a 
 collection or assemblage of cells, joined together (see 
 Plate XIV.), just as a house consists of a number of 
 separate bricks cemented together with mortar. An 
 elaborately formed tree is composed of exactly the same 
 kind of material as the simplest plant. Those objects 
 which consist of only a single cell are said to be uni- 
 cellular, while those consisting of many cells are multi- 
 cellular in composition. In studying the plant cell we 
 are beginning at the lowest rung in the study of life itself. 
 Plant cells were discovered about a hundred years 
 
 (2,084) 73 10 
 
74 THE MICROSCOPE. 
 
 ago. The early workers had some peculiar theories about 
 their behaviour. For instance, it was at one time be- 
 lieved that the walls of the cell were its most important 
 part that they were indeed the cell itself. It was also 
 thought that the cell contents were merely food for the 
 cell walls, and that in those cases where the cells were 
 empty the contents had been digested or assimilated by 
 the cell walls. Later it was discovered that the contents 
 of the cell are actually of far greater importance than 
 the walls, and that the cell walls did not feed on the cell 
 contents. It was also found that the cause of some cells 
 being empty was due to the fact that the contents of 
 the cell had dropped out, or had been accidentally shaken 
 out, when the specimen was being prepared for observa- 
 tion under the microscope. 
 
 The contents of vegetable cells was first recognized in 
 *835 by the French naturalist Dujardin, who described 
 the substance as being formed of a greyish, semi-trans- 
 parent material of a slimy nature. In 1846 this jelly-like 
 substance was named " protoplasm " by the botanist 
 Hugo von Mohl. The word protoplasm comes from the 
 Greek proton, meaning " first/' and plasma, " formed 
 substance/' Protoplasm is often stained by different 
 coloured dyes by microscopists, for by these means it is 
 rendered more easily visible. 
 
 II. 
 
 If we make a section of some plant, or vegetable by 
 cutting off a thin slice with a razor or sharp knife and 
 examine it with the microscope, we see at once that it is 
 composed of minute hollow bodies. Often their arrange- 
 
PLANT CELLS. 
 
 75 
 
 ment is symmetrical and very pleasing, as in the case of 
 rattan cane (a, Plate XIV.) and of many flower buds. 
 If the substance be placed in water for a few days until 
 it becomes decomposed, these hollow bodies will separate 
 and their different forms will then be clearly seen. They 
 are the plant cells of which we have been speaking, and 
 are generally of a round nature. They are also found 
 in other forms, such as oval or star- 
 shaped. Occasionally they lose their 
 cell-like shape entirely and appear as 
 spirals, and are thus difficult to recog- 
 nize as cells (Fig. 27). The cells of 
 some plants are pressed closely to- 
 gether, but others are loosely packed. 
 Cells of the latter kind are to be found 
 in most pulpy fruits. 
 
 If we examine the cells of a thin 
 section from some soft fruit like an 
 apple, we find that in the interior of 
 each is a central spot, or nucleus (a, 
 Fig. 28). It is from these nuclei that 
 the cells originate. New cells are born 
 from a similar nucleus, or by the divi- 
 sion of a thin membrane in the centre 
 of the cell. This membrane takes the place of the 
 nucleus and is called the " primordial cuticle." Cells 
 thus formed are either free like those in the illustration, 
 or are packed closely together. In the latter case they 
 are said to form a tissue. 
 
 When a section of a fruit is made in which the cells are 
 pressed together equally and on all sides, the cells are 
 
 a if c 
 
 FIG. 27. Plant ves- 
 sels, (a) Spiral, 
 from leaf-stalk of 
 rhubarb. (&) The 
 same, unrolled, (c) 
 Ring-like, from root 
 of wheat. 
 
76 THE MICROSCOPE. 
 
 seen to be hexagonal in shape. Such cells may be seen 
 in the pith of most plants and especially in the common 
 elder (b, Fig. 28). Another type of cell is the stellate or 
 star-shaped found in most water-plants, such as the com- 
 
 a C 
 
 FIG. 28. Vegetable-cells, (a) Apple, (b) Elder, (c) Rush. 
 
 mon rush or sedge (c, Fig. 28). As will at once be seen, 
 these stellate-shaped cells allow a large quantity of air 
 to be admitted in the spaces between the cells, and the 
 plant is thus made more buoyant and better adapted 
 for growth in water or marshy places. 
 
 III. 
 
 The skin or thin membrane covering our bodies and that 
 of the bodies of animals is called the epidermis. If the 
 leaf of any plant be examined, a similar thin layer or 
 outer skin will be seen ; this is also called the epidermis 
 or cuticle. It is made up of minute cells, and varies in 
 form in different plants. Scattered over the surface of 
 this epidermis are curious little apertures or pores. 
 These are the stomata, a Latin word meaning " little 
 mouths/' Through them the plant breathes for plants 
 require to breathe just as animals do, though the process 
 
PLATE XVIII 
 
 From a photo-micrograph by] 
 
 ! 
 
 From a photo-micrograph by] 
 
 (b) [A. E. Smith 
 
 (a) SPIRAL VESSELS FROM RHUBARB, (b) SECTION OF COAL, 
 SHOWING FOSSIL ROOTS AND STEMS 
 
STOMATA. 77 
 
 is not effected by the same means. When we " breathe 
 in " we inhale oxygen into our lungs, and when we 
 " breathe out " we exhale carbon dioxide. Our lungs 
 have extracted the oxygen they needed and sent back 
 the poisonous carbon dioxide, for which they have no 
 use. Plants are differently constituted, however, for 
 they actually need the carbon dioxide which we cannot 
 use. This is fortunate, as is also the fact that plants 
 give out oxygen during the hours of daylight, for they 
 thus help to purify the air. 
 
 The stomata are generally found to be minute oval 
 openings, having at each side a crescent or kidney- 
 shaped guard-cell which, by opening or closing, regulates 
 the amount of air admitted to the leaf (Plate XV.). 
 Stomata are well seen in the leaf of the hyacinth, for in 
 this plant the cells of the epidermis are transparent, and 
 the stomata filled with green colouring matter. Stomata 
 are found to be most abundant on the lower side of leaves ; 
 indeed, on some plants they are only found there. They 
 vary in size in different plants. In water-cress, for 
 instance, they are very small, and the cells of the epi- 
 dermis are not straight like those of the hyacinth but 
 sinuous, winding about like a river. 
 
 Just as the stomata vary in size, so too do they vary 
 in number in different plants. It has been estimated that 
 the under-surface of leaves of the hydrangea have 160,000 
 stomata to the square inch. In leaves which float on the 
 surface of the water the stomata are found on the upper 
 surfaces only. Those leaves which live entirely sub- 
 merged in water have no stomata. 
 
78 THE MICROSCOPE. 
 
 IV. 
 
 When cells retain their original shape the tissue they 
 form is called " cellular.'' But when the cells become 
 elongated, or unite together forming an elongated tube, 
 the tissue thus formed is called " vascular." The interior 
 of vascular tissue may be plain or marked by dots or 
 pores. 
 
 In the ribs of leaves and the stems of plants elongated 
 fibres are seen lying side by side. These may also be 
 observed in a longitudinal section of wood (a, Plate XVI.). 
 This appearance is called " ligneous or woody tissue," 
 and of it are composed nearly all wood and the more 
 woody parts of plants. The object of woody formation 
 in plants is to furnish a support for the plant. When 
 this support is once formed the cells of which it is com- 
 posed do not take any further share in the growth of 
 the plant. They do, however, help to convey fluid from 
 the roots upwards through the stem and branches to 
 the leaves. 
 
 Large open tubes are observed in the transverse sections 
 of most plants which look like circular openings in the 
 section and are called " ducts " (b, Plate XVI.). Those 
 which are marked with pores as in the case of deal, 
 for example are called " dotted ducts." They are 
 formed by deposits in the interior of the tube and are 
 found in great variety. 
 
 The cone-bearing or fir tribe of plants have a well- 
 known marking of the vascular tissue, called " glandular 
 woody tissue." In the case of the common pine tree, 
 for instance, little circular discs are seen, each having 
 
SPIRAL CELLS. 79 
 
 a black dot in its centre (a, Plate XVII.). These may 
 be observed easily by making a thin longitudinal section 
 of a piece of wood. If a drop of water be placed on the 
 section the circular discs will be more clearly seen. 
 
 V. 
 
 If we bend and break the stem of a strawberry leaf we 
 find that the two pieces are held together by a number of 
 delicate threads of a spiral nature. These spiral vessels 
 are found in the stems and leaves of many plants, and 
 resemble in some cases rhubarb, for instance long 
 compressed springs (a, Plate XVIII.). Occasionally 
 the continuity of the spiral is broken, or even only a ring 
 of thread remains to mark the place where the complete 
 spiral would have been. When this is the case the ring- 
 like vessels are called " annular." Annular vessels are 
 easily found in the leaves of garden rhubarb, or in the 
 roots of growing wheat (c, Fig. 27). Yet another form 
 of spiral vessels is that found in the roots and stems of 
 ferns. Here the vessel is found in a many-sided form, 
 and because of its ladder-like appearance is known as 
 " scalarif orm tissue" (b, Plate XVII.). Not only do 
 the spiral cells give lightness and elasticity to a leaf or a 
 stem, but they also act as trachea for the breathing organs, 
 keeping the air passages open, just as the spiral wire 
 inside a garden hose-pipe keeps it from " kinking." 
 
 If a thin transparent section of a piece of the bark of 
 a plant be examined under the microscope its structure 
 may be studied. Outside is the epidermis or cuticle 
 corresponding to the bark of a tree and below are two 
 layers of cellular tissue, the innermost layer of which 
 
8o THE MICROSCOPE. 
 
 is clearly seen to be woody tissue. The outer cellular 
 layer of some trees is very fully developed and is known 
 as cork. Cork is obtained from the bark of an oak tree 
 grown principally in the Levant and in Portugal. This 
 cellular structure of cork may be plainly seen in a very 
 thin section, the cells being of a square shape and often 
 pitted. 
 
 VI. 
 
 Ages ago, in what is called the Carboniferous period of 
 the Earth's history, the world was in a very different state 
 to that in which we know it to-day. The atmosphere was 
 saturated with water vapour, the rainfall was very heavy, 
 and the climate was a great deal warmer than at the 
 present time. The air contained a large amount of 
 the poisonous gas carbon dioxide, the plants and trees 
 grew very fast, and because of the great quantities of 
 water were soft and juicy. In this manner a sort of vast 
 swampy jungle came into existence, perhaps not unlike 
 the dense mangrove-swamps which now fringe the coast 
 of Florida. Pine trees, ferns, and giant horse-tails grew 
 alongside club mosses fifty feet in height, and six feet 
 in diameter. These masses of vegetation lived and died 
 and became covered with deposits of sand and mud. 
 The pressure of these deposits became so great that the 
 trees and leaves were pressed flat, forming layers of 
 material several feet thick. This pressure, coupled with 
 the internal heat of the Earth which partly baked this 
 material, continued until in due time the trees and 
 vegetation were transformed into coal. 
 
 Not only have we learned these facts concerning the 
 
PLATE XIX 
 
 Starch grains from a potato 
 
COAL. 81 
 
 origin of coal from the fossil trees and plants found in the 
 coal measures, but we know of them also because if a 
 thin section of coal be examined in the microscope it 
 shows the material to be of vegetable origin. (Notice 
 the similar appearance of b, Plate XVI., and b, Plate 
 XVIII.) 
 
 Coal is a somewhat difficult object to examine under 
 the microscope, and to enable us to see its construction 
 in detail we must have a very thin section. This may 
 be obtained by fastening a suitable piece to a glass slide 
 with Canada balsam, and when this has set firmly 
 rubbing the coal down on a fine stone, until it is thin 
 enough to be satisfactorily examined. From such a 
 section we find that coal shows both cellular and vascular 
 tissue. The latter tissue is of the glandular woody 
 variety, and from this fact we learn that the trees or 
 plants which formed the coal belonged to the cone- 
 bearing or fir family. This inference is fully borne out 
 by the remains of these trees and plants which have been 
 preserved in the coal measures. 
 
 VII. 
 
 We have dealt with the outside forms of plant tissues, 
 and we are now to learn something of the cell contents. 
 Here we find veritable store chambers where may be seen 
 secretions of starch, sugar, gum, oils, and of colouring 
 matter. If the cells of the growing parts and roots of 
 plants be examined under the microscope a number of 
 round grains are to be seen. These are particularly 
 abundant in the tubers of a potato and in wheat, corn, 
 and other cereals. In a section of a potato the grains 
 
 (2,084) 1 
 
82 THE MICROSCOPE. 
 
 may be seen lying in the cells of which the potato is 
 composed (a, Plate XIX.). If a solution of iodine be 
 made up by adding five grains of iodine and five grains 
 of iodide of potassium to an ounce of distilled water, and if 
 a drop be applied to the potato cells, the rounded granules 
 will at once become a beautiful deep blue in colour. This 
 proves that they are starch, for no other substance will 
 change to blue in this way when iodine is applied. 
 
 Granules of starch are found in some part or other of 
 most plants, and they are of many sizes and shapes. 
 The starch-grains of wheat are rounded and of different 
 sizes (b, Plate XIX.). Those of the oat may be recognized 
 by the fact that the small granules stick together in 
 globular forms, which when broken up give place to very 
 irregular grains (c, Plate XIX.). The largest known 
 starch-grains are those of arrowroot called Tous-les-Mois 
 (a, Plate XIX.). As in the case of the starch-grains of 
 the potato, these grains look as though they consisted 
 of numbers of plates, laid one upon the other, and 
 decreasing in size towards the top. Often a small black 
 irregular spot is seen towards the centre of the grains. 
 The starch of Indian corn has a peculiar marking like 
 a dark cross at the centre of each grain (b, Plate XIX.). 
 Sago and tapioca are good objects for examination, as 
 they consist almost entirely of starch (c, Plate XIX.). 
 
 Often in examining leaves and stems with the micro- 
 scope we come across numbers of minute objects em- 
 bedded in the plant. They are found in the cell cavities 
 of many plants, and also may be seen in the white milky 
 juice from the dandelion and in the juice of the common 
 hyacinth. These are raphides, a name derived from the 
 
RAPHIDES. 83 
 
 Greek word raphis, meaning " a needle/' Indeed the 
 raphides do look like bundles of minute needles, lying 
 side by side (a, Fig. 29). They vary in size from ^ to 
 ToViy inch, and are really deposits of insoluble salts in 
 the fluids of the plant. 
 
 Rhubarb raphides consist of oxalate of lime, a mineral 
 found in many other plants (c, Fig. 29). Raphides are 
 most abundant in rhubarb, especially in Turkey or 
 Russian rhubarb, and sometimes they are so numerous 
 that if the root be chewed it seems quite gritty. Raphides 
 
 a 
 
 FIG. 29. Raphides. (a) From hyacinth, (b) Bundle contained in a cell 
 from leaf of aloe, (c) From stalk of rhubarb, (d) From outer coat 
 of an onion. 
 
 are also found abundantly in the bulbs of the hyacinth 
 (a, Fig. 29), tulip and onion (d, Fig. 29), and in the 
 apple-tree, lime, ash, elm ; in the husks of rice, wheat, 
 and in other grains. Sometimes they occur in all parts 
 of the plant in the wood, pith, bark, root, leaves, 
 sepals, petals, fruit, and even in the pollen. Raphides 
 have been formed artificially by placing cells of rice- 
 paper which recently have been filled with lime-water in 
 a weak solution of oxalic acid. The artificial raphides 
 thus formed exactly resembled the natural raphides of 
 rhubarb. 
 
8 4 
 
 THE MICROSCOPE. 
 
 VIII. 
 
 In most plants the epidermis or cuticle is smooth, 
 and apart from the features already described has few 
 other points to interest us. In some plants, however, 
 the cuticle forms projections called papilla or warts 
 
 FIG. 30. Plant-hairs, (a) Rudimentary hair from pansy, (b) Simple 
 hair from common grass, (c) Star-shaped hair from hollyhock. 
 (d) Hair from throat of pansy, (e) Many jointed, tapering hair 
 from common groundsel. (/) Star-shaped hair from lavender leaf. 
 (g) Beaded hair from pimpernel, (h) Glandular hair from tobacco 
 leaf, (i) Warty-surfaced hair from verbena, (j) Hair from leaf of 
 chrysanthemum. 
 
 (*', Fig. 30). Sometimes also there are glands, prickles, 
 or hairs to be examined. Papilla are minute swellings, 
 and consist of one or two cells only. Warts are larger 
 and of a harder nature. The glands contain secretions ; 
 
PLATE XX 
 
 rrom a photo-micrograph byj 
 
 THE "STING" OF A NETTLE 
 
 [A. Flatters 
 
PLANT-HAIRS. 85 
 
 the prickles are stiff and sharp, and the hairs are long 
 and of numerous varieties. In the pansy is found an 
 example of papilla which may be considered to be a 
 rudimentary hair (a, Fig. 30). There are also in the 
 same flower others which are longer and more closely 
 resemble true hairs. Others again are yet longer, and 
 present the appearance of a knotted branch, due to the 
 sides of the hair having drawn together (d, Fig. 30). 
 Simple hairs may be found on many grasses, such as 
 wheat, barley, and oats (b, Fig. 30). The hairs of ground- 
 sel are composed of several cells, each of which has a 
 separate nucleus (e, Fig. 30). The pimpernel has hairs 
 resembling a string of beads (g, Fig. 30), while those of 
 the chrysanthemum leaf are branched and resemble 
 the letter T (/, Fig. 30). Star-like hairs are found on the 
 under-surface of the leaf of the hollyhock (c, Fig. 30), 
 and branched star-like hairs are found covering lavender 
 (/, Fig. 30). 
 
 Plants belonging to the same species have similar 
 kinds of hairs, so it is quite possible to identify a species 
 of plant by examining only the hairs of its leaves. For 
 instance, the hairs of the tobacco plant are very char- 
 acteristic, for they terminate in a knob (h, Fig. 30), 
 and the quality of tobacco may be tested by the presence 
 of these hairs. Though tobacco leaf may be imitated 
 and the mixture adulterated, it is impossible to imitate 
 the peculiarities of these microscopic hairs. 
 
 Some plants have hairs with glandular cells, which 
 secrete oily or resinous matter. The leaves of the stinging 
 nettle are a well-known example, for the hairs have glands 
 containing an irritant fluid at their roots. The ends of 
 
86 THE MICROSCOPE. 
 
 these hairs terminate in an extremely fine point, so 
 delicate that it is broken off by the slightest touch, and 
 the poisonous fluid flows out, entering our flesh and 
 causing the " sting " (Plate XX.). 
 
CHAPTER VIII. 
 FLOWERS. 
 
 I. 
 
 FLOWERS, beautiful though they always are even 
 without any optical aid, appear much more so in 
 the microscope. The wonders of their construction, the 
 marvellous delicacy of their minute parts, and their 
 gloriously beautiful colouring are a thousand times more 
 wonderful when magnified. Petals, sepals, stamens, and 
 pistils all have a story to tell, and only await the coming 
 of the botanist to lay this bare. 
 
 Grasses furnish us with many examples of minute 
 flowers, which are revealed in all their beauty under the 
 microscope. The tiny floret of the meadow-grass, for 
 instance, exhibits stamens covered with pollen, and 
 feathery stigmas attached to a minute ovary. The lily- 
 of-the-valley a larger flower than that of meadow-grass 
 is of triplet structure, and is of great beauty. The leaf, 
 even to the unaided eye, shows parallel veins, and the 
 single seed chamber, if examined carefully and in detail, 
 will furnish much interesting information. 
 
 Among the most interesting of flowers are the orchids, 
 of which many thousands of species are known. They 
 
 87 
 
88 THE MICROSCOPE. 
 
 are more common in the tropics than in our northern 
 latitudes, and many have been the exciting adventures 
 of orchid hunters. You may have read accounts of their 
 exploits in more than one book. Some of the exotic 
 or foreign orchids have been successfully cultivated in 
 England by imitating the natural conditions of heat 
 and moisture of the forests of the Amazon, of India, 
 and of other countries. We ourselves may not be so 
 fortunate as to be able to examine any of these exotic 
 species, but we may look for some of the more lowly 
 members of the great family which grow wild in this 
 country. For instance, in June and July the spotted 
 orchis is found in chalk and limestone districts. The bee 
 orchis and the fly orchis suggest the peculiar shape these 
 flowers take. 
 
 In the case of most flowers, the beautifully marked 
 tissue of which they are composed is worthy of examina- 
 tion. Spiral fibres, such as have already been described, 
 may be found also in these cells. The fibres are well seen 
 in the anthers of the furze, while in the dead white nettle 
 they are found growing in an irregular manner. In the 
 anthers of the narcissus the cells are almost completely 
 annular, and look like a number of disconnected rings. 
 Yet another form is that of the star-shaped fibres of the 
 crown imperial which radiate from a central point. 
 
 The cone-bearers, the pines and firs, also present many 
 objects of interest the peculiar fibre-like appearance 
 of the cones, the cellular construction of the " pine- 
 needles," and the resinous juices often found oozing from 
 their branches. The catkin-bearing trees such as the 
 willow, birch, and alder have curious flowers and seed 
 
PLATE XXI 
 
 . 
 
THE COMPOSITES. 89 
 
 vessels, which abound with microscopic objects. So too 
 do the members of the highest order of dicotyledons, the 
 Ranunculacea, or rose family. These include the fruit 
 trees such as plum, apple, cherry and all flowers 
 which resemble a rose in their structure. 
 
 Such flowers as the daisy and the dandelion are not 
 single flowers like the buttercup and the rose. When 
 magnified they are at once seen to be colonies of flowers, 
 that which we call the daisy being really made up of a 
 number of very small flowers. These flowers belong to 
 
 FIG. 31. Section of a daisy. 
 
 the Composite^, the composite or compound flowers. 
 Cut through the flower-head of a daisy and you will see 
 the yellow florets are quite separate and resemble small 
 bell-shaped tubes (Fig. 31). When matured or fully 
 grown they show two tiny stigmas outspread. Inside 
 the tube of the floret is a ring of stamens, with their 
 pollen cases or anthers lying side by side, forming a tube 
 enclosing the pistil and lying within the floral tube itself. 
 This anther tube is a distinctive feature of the flowers of 
 the family to which the daisy belongs. 
 
 The white florets outside the yellow are not so numerous 
 
 (2,084,1 12 
 
90 THE MICROSCOPE. 
 
 as the latter, but are more conspicuous by their shape and 
 size. They attract insects, just as do the markings and 
 similar features on other flowers, directing them to where 
 the nectar is secreted. The white floret has a short 
 tube with a long blade-like ending (Fig. 31). A pistil 
 with two stigmas may be seen in the tube, but no stamens 
 exist. The pistil is not affected by pollen, and therefore 
 does not produce any seeds, the work of reproduction 
 being accomplished by the yellow florets. 
 
 II. 
 
 Whenever possible collect and examine pollen grains 
 from different flowers, for they vary in shape and size, 
 
 PIG. 32. Pollen grains, i. Heath. 2. Hollyhock. 3. BuUercup. 4. 
 Mallow. 5. Tulip. 6. Rose. 7. Iris. 8. Clematis. 9. Passion-flower. 
 10. Anemone, u. Dandelion. 12. Auricula. 13. Primrose. 14. Hazel. 
 
 each species of plant having its own particular form. 
 It would be interesting for every possessor of a micro- 
 scope to study all these different appearances, recording 
 
POLLEN GRAINS. 91 
 
 in an observation book the varying features of each, 
 and perhaps giving a rough sketch of the pollen grains 
 described. 
 
 The pollen grains of many plants are oval (5, 6, etc., 
 Fig. 32). Those of the hazel are triangular (14, Fig. 32) ; 
 those of the heath, three-lobed (i, Fig. 32). Those of 
 the dandelion, and of many other plants of the Com- 
 positecz order, are beautifully sculptured (n, Fig. 32), 
 while the grains of the passion-flower are engraved with 
 three rings (9, Fig. 32). Those of the hollyhock and 
 mallow are covered with sharp-pointed spines and look 
 like miniature pin-cushions (2 and 4, Fig. 32). These 
 projections enable the minute grains to more easily 
 hold fast to surfaces on which they are cast. 
 
 All these pollen grains are actual plant cells, and their 
 purpose is to be carried to the pistil to fertilize the young 
 ovules which form the seeds of the plant and from which 
 young plants grow. 
 
 III. 
 
 The microscope has shown us exactly how the fertiliza- 
 tion of flowers takes place. In this great work insects, 
 and particularly bees, are prominently concerned. Some 
 flowers, like those of the grasses and the common hazel, 
 are fertilized by the wind, but the majority of flowers 
 depend upon insects for the accomplishment of this 
 all-important operation. 
 
 Let us try to understand exactly what takes place 
 in fertilization and why it is necessary. To enable us to 
 study this matter we will choose a daffodil about which 
 to speak, for this flower is both a good example and 
 
92 THE MICROSCOPE. 
 
 easily obtainable. We know that the daffodil is made up 
 of " flower-leaves " and that there is no calyx as in the 
 case of the primrose. The corolla is a deep yellow tube, 
 and to it the flower-leaves are joined. If we cut the flower 
 in two, down the centre, we find there is a long rod which 
 is called the style (b, Plate XXIIL). At the end of this 
 there is a sticky knob, the stigma. Six smaller rods 
 are grouped round the style, and these are called the 
 stamens. They are thickened at the end near the stigma, 
 these thickenings forming the anthers. The anthers are 
 the pollen-bearing parts of the flower, and though the 
 position of each often varies you will find both anthers 
 and stigma in nearly every kind of flower. 
 
 Below the corolla of the daffodil is the ovary, the 
 chamber where the seeds are formed. In the ovary we 
 can see, with the naked eye, a number of round objects 
 of a transparent nature. These are the ovules, and in the 
 course of time they may become seeds. There is, how- 
 ever, a remarkable difference between the ovule and the 
 seed. If we planted one of the former it would never 
 grow into a plant, but would simply wither away and 
 decay in the ground. On the other hand, if we set a 
 seed, sooner or later it would spring up and become 
 a plant resembling that from which the seed was 
 taken. 
 
 An ovule only becomes a seed after being fertilized, 
 and this is accomplished by some pollen being placed on 
 the stigma. The style is a kind of tube connected with 
 the ovary. When the grains of pollen reach the stigma 
 they adhere to it, because it is viscid, or sticky. The 
 viscid, sugary secretion with which it is covered stimulat- 
 
PLATE XXII 
 
 From a drawing by] ^Ellison Hawks 
 
 POLYCYSTINA 
 
FERTILIZATION. 
 
 93 
 
 ing the pollen grains to growth, causes them to sprout 
 and send out long shoots called pollen tubes. These 
 pollen tubes grow down the style, 
 forcing their way between its cells 
 (Fig. 33). They often attain an ex- 
 traordinary length, sometimes extend- 
 ing for several inches. 
 
 The cells of the style also contain 
 a sugary liquid, and these further 
 nourish the growth of the pollen 
 tubes, which ultimately reach the 
 ovary where the ovules are found. 
 Each ovule has a minute opening 
 called the micropyle, or " little gate," 
 and here the pollen tube enters. 
 Having done this it pours into the 
 ovule nutrition from the pollen grain 
 above, the ovule undergoes certain 
 important changes called fertiliza- 
 tion and then becomes a true seed. 
 
 tion of stigma. 
 
 IV. 
 
 Just as the pollen grains form an interesting study, so 
 too do the seeds of plants, and, as in the case of the former, 
 they vary in form and size in different plants. As we have 
 seen, after the ovule has been fertilized it becomes a seed, 
 containing the embryo or young plant. In many plants 
 the seed is sufficiently large to be seen by the unaided 
 eye, but the microscope will undoubtedly reveal new 
 features of interest. The seed is covered with an outer 
 membrane, called the "testa," and in some cases this 
 
94 
 
 THE MICROSCOPE. 
 
 is often curiously marked. The seed of a red poppy, for 
 instance, is kidney-shaped, and has peculiar reticular 
 markings (a, Fig. 34). The seed of black mustard is of 
 a more circular shape, and its surface is covered with a 
 delicate network of fine lines (b, Fig. 34). The seed of the 
 snap-dragon is covered with irregular ridges, and granular 
 markings (c, Fig. 34). A somewhat similar-looking seed 
 
 a 
 
 FIG. 34. Plant-seeds, (a) Red 
 (c) Snapdragon. ( 
 
 i (b) Black mustard, 
 ckweed. 
 
 to that of the mustard is the chickweed, which is covered 
 with numerous blunt projections and resembles a minute 
 clove-ball (d, Fig. 34). 
 
 In some plants the seeds adhere to the fruit, which is 
 often incorrectly called the seed. Among these are the 
 aniseed, dill, and carraway. Some of the fruits of these 
 plants are covered with minute hooks, 
 
CHAPTER IX. 
 FUNGI AND MOULDS. 
 
 I. 
 
 OFTEN when walking in the country we see mush- 
 rooms and toadstools ; sometimes, too, beautifully 
 coloured fungi are noticed on or near trees. Although 
 all these are well known to belong to the fungus family, 
 there are many other members of the same family which 
 are not so well known. It is not necessary to walk 
 into the country to find objects of this class, for mouldy 
 cheese will provide interesting examples, as also will 
 decayed portions of fruits and any other articles which 
 have " gone mouldy." 
 
 We have already seen something of one-celled plants. 
 By far the greater number of these are found living in 
 rivers, streams, or ponds. Some, however, exist on moist 
 rocks or on old walls. One of these is " Gory Dew " 
 (Palmella cruenta), which is of very simple structure 
 indeed, consisting simply of minute globular cells (/, Fig. 
 35). It causes a red stain to appear on the surface of 
 damp objects, and belongs to the same family as the 
 red snow plant. 
 
 Darwin tells us in The Voyage of the Beagle that during 
 
 96 
 
96 THE MICROSCOPE. 
 
 his passage of the Cordillera the footsteps of the mules 
 in the snow were stained pale red, and a little of the 
 snow rubbed on paper gave it a pale red tinge. The red 
 
 f 
 
 FlG. 35. Fungi, (a) Puccinia graminis. (b) Mucor mucedo, a fungus 
 from mouldy bread, (c) " Cholera-fungus." (<i) Yeast cells. 
 () Vinegar plant. (/) " Gory Dew " (Palmetto, cruenta). 
 
 colour was entirely due to the presence in large numbers 
 of the tiny plant Pwtococcus nivalis. The phenomenon, 
 of somewhat rare occurrence in this country, was noticed 
 in many places after a severe snowstorm in 1908. The 
 
PLATE XXIII 
 
FUNGI. 97 
 
 wonderful little plant Protococcus nivalis appears on the 
 surface of the snow, and so quickly do the cells reproduce 
 themselves that an Arctic or Alpine landscape may be 
 changed from white to red in a single night. This rapid 
 growth of Protococcus nivalis, and its peculiar red colour, 
 gave rise to many fearsome tales in olden days, for then 
 the true nature of the phenomenon was not understood, 
 it being thought that tlie snow was stained red with 
 blood. 
 
 Examined in the microscope, Protococcus nivalis is seen 
 to consist of numbers of spheres, in colourless cases, 
 each no more than T^^TT mcn in si 26 - When perfect, 
 the spherical cells are not unlike a red-currant berry. 
 Minute though they are, the cells perform all the functions 
 of growth and reproduction as completely as the larger 
 and more highly organized members of the vegetable 
 kingdom. 
 
 There are many other members of the same family, 
 one form attacking bread, and another potatoes. In each 
 case the bread and potatoes are given the appearance 
 of having been dipped in blood. 
 
 II. 
 
 Of similar structure is the yeast plant, or fungus, by 
 the aid of which bread is made. It belongs to a group 
 called Saccharomyces, or sugar fungi. Yeast cells furnish 
 us with an interesting and typical example of the con- 
 struction of cells, of their growth and of their method 
 of reproducing themselves. The cells commence their 
 life as a creamy foam, floating on the top of a brewer's 
 vat. Under the microscope they look like a crowd of 
 
 (2,084) 13 
 
98 THE MICROSCOPE. 
 
 yellowish grains. Most of them float about quite alone, 
 or isolated, but here and there are some which are joined 
 together in chains, like beads on a string. They resemble 
 oval globes in shape, and on an average are ^ws mcn 
 in size (d, Fig. 35). Each is filled with almost colourless 
 matter, in which are to be seen one or more bubble-like 
 objects, or vacuoles. 
 
 When yeast cells are placed in a suitable liquid or 
 fermentable fluid, as it is called they grow, or vegetate. 
 Each cell then commences to put out one or two pro- 
 jections or buds, and looks like a large potato with a 
 smaller one attached. These projections are the beginning 
 of the young cells, which are really offshoots. When they 
 are sufficiently developed they become detached and 
 break away from the parent, forming complete cells. 
 Later, they themselves become parent cells in their 
 turn, and in this manner a single yeast cell develops into 
 chains of four, five, or six cells in the space of only a few 
 hours. 
 
 If the fermentation of the liquid in which they are 
 placed is stopped, the cells composing these chains break 
 away and become detached. So long as the cells remain 
 in liquid from which they can extract food, or nutriment, 
 the birth of new cells will continue. If the liquid in which 
 the cells are placed becomes unsuitable if, for instance, 
 the sugar it contains be used up or if it becomes dried 
 up, the contents of the cells contract. The spores, or 
 seed germs, then become inactive for the time being. 
 Although they may become quite dry to all outward 
 appearance, they are not killed, but still contain the 
 mysterious element life. In fact, the cells are not easily 
 
FUNGI. 99 
 
 deprived of their living contents by being subjected to 
 either high or low temperatures, for as soon as conditions 
 are once more favourable they revive and recommence 
 reproducing themselves. 
 
 III. 
 
 A minute vinegar plant may be cultivated by simply 
 allowing vinegar to stand for a little time in a jar and 
 exposed to the air. At first the vinegar plant is seen to 
 be composed of elongated cells, looking like a collection 
 of pieces of finely chopped cotton or thread (e, Fig. 35). 
 
 More fully developed thread-like fungi are often found 
 in decomposing fluids. One of them is misnamed 
 " Cholera-fungus," which was at one time believed to 
 be the cause of cholera (c, Fig. 35). Sometimes specimens 
 of this fungus may be obtained by exposing a piece of 
 damp glass or similar substance to the air in a damp 
 and unwholesome cellar or room. 
 
 It is believed that all these simple fungi are really 
 different forms of the fungus which produces the common 
 mould known as Muccr mucedo. This mould which is 
 found almost everywhere attacks jam, fruit, and vege- 
 tables, especially those of a sugary or starchy nature. 
 Sometimes we see peaches and other delicate fruits 
 wrapped in cotton-wool or tissue paper. The wrap- 
 ping acts as a preventive against mould, which quickly 
 attacks bruised fruits, the spores obtaining an entrance 
 to the fruit through the openings in the skin caused by 
 the bruises. 
 
 If we carefully collect some common mould and examine 
 it with the microscope, we find that the main mass 
 
loo THE MICROSCOPE. 
 
 known as the " mycellium " is composed of a large 
 number of hyphce, or knob-like structures ; they stand 
 upright, and each one terminates in a round swelling 
 (b, Fig. 35). These round objects are the sporangium, 
 or seed cases, as they may be called, and contain thousands 
 of minute oval bodies, named the endo-spores. When 
 these are ripe they burst, and the spores are scattered in 
 all directions as a very fine, invisible dust. 
 
 Mould is found almost everywhere where there are 
 substances which are exposed to damp and decay. 
 We find moulds in our gardens, in our houses, in our 
 food, and in our clothes. A form of mould even is 
 often able to obtain a sufficient supply of nourishment 
 to exist in the paste of wall-paper and in old books. 
 Sometimes moulds look like spots or markings on the 
 leaves of plants. At others they appear as mildew, 
 smut, or rust. These latter names do not mean the 
 smut of the factory chimney, nor the rust of old iron ; 
 they are the names given to moulds because they closely 
 resemble these objects in appearance. The smut mould 
 on plants is a dirty-looking growth, and the rusts are 
 growths of a distinctly reddish colour. 
 
 IV. 
 
 One of the most troublesome of these moulds is that 
 called " corn mildew," although it sometimes attacks 
 wheat and other grasses as well as corn. It is caused by a 
 fungus called the Puccinia graminis. This particular form 
 of mould has been closely studied with the microscope, 
 and it is now believed that it commences its existence 
 in the berberry plant, the leaves of which when attacked 
 
PLATE XXIV 
 
FUNGI. 101 
 
 appear to be covered with a fine red rust. Under the 
 microscope these rust-like markings are seen to consist 
 of myriads of structures resembling minute cups in 
 shape, and filled with orange-coloured dust (Fig. 36). 
 This dust is the spores or microscopic 
 seeds of the fungi, and it is esti- 
 mated that each minute cup contains 
 no less than a quarter of a million 
 spores ! Later, the fungus passes 
 through different stages, at one time 
 having the appearance shown at a, 
 
 Fig. 35. FIG. 36. Cluster- 
 
 T-I M t i CUDS on underside 
 
 The corn mildew is so common, and of leaf, 
 its spores so numerous, that they 
 mingle with the seeds of the grain when ground into 
 flour. If carefully looked for they may be found in 
 almost any piece of bread, if it be examined under the 
 microscope. 
 
 V. 
 
 Fungi often attack plants and cause irregular spots to 
 appear on their leaves. These are generally seen in 
 summer and autumn, and may be of a yellow, red, or 
 black colour. A common form, and one much dreaded 
 in many parts of the country, is the potato disease as 
 it is commonly termed. There are several forms of this 
 disease, but that generally met with is Phytophthora 
 infestans, also called " the late blight." This fungus is 
 found wherever the potato is grown, and in this country 
 generally appears about July or August. The leaves of 
 the potato lose their brilliant green colouring, becom- 
 
102 THE MICROSCOPE. 
 
 ing mottled and patched with yellow. They gradually 
 change to dark brown and perhaps even to black. Some- 
 times the stems themselves are affected. 
 
 The tubers, as the potatoes are called, accumulate 
 starch and other matter. For the formation of this 
 starch they depend entirely upon the leaves, which form 
 it with the aid of sunshine. Thus, it is quite easy to 
 understand that if the leaves are attacked by the mould, 
 and die, the tubers do not grow to their full size. In- 
 stead of the potatoes being large and healthy they are 
 much smaller, and the crop is diminished. In countries 
 like Ireland, where the poorer people depend for their 
 food mainly upon potatoes, it may be a very serious 
 thing if the disease attacks the crops. 
 
 VI. 
 
 Many forms of fermentation are due to the action of 
 microscopic fungi. There is, for instance, that form 
 which takes place in wine-making. The fermentation of 
 the juices of the grape or whatever other fruit is used 
 commences with the development of a minute fungus, 
 the germs of which were already present in the fruit, or 
 in its skin, when it was gathered. 
 
 The common drink in Japan is a kind of beer called 
 saki, and this is made by fermenting rice. Another 
 drink made by the Japanese is soy, which is obtained by 
 mixing the beans of the soja with an equal quantity of 
 roughly ground wheat or barley, which is then placed in 
 a warm place to ferment. In both these cases the action 
 is due to a microscopic fungus which, by feeding on 
 certain substances in the mixture, causes a chemical 
 
LICHENS AND MOSSES. 103 
 
 change to take place. This change is called fermenta- 
 tion. 
 
 VII. 
 
 There are also numerous lichens, mosses, and ferns 
 which abound with interest to the microscopist. One 
 particular form of lichen, of a yellow colour, is often seen 
 on railings and on the bark of trees. It resembles pieces 
 of dried yellow paper, and is composed of scales which 
 show on their surface spots of deeper yellow colour. Cut- 
 ting through these, we find a number of cases, or asci, 
 containing the spores. 
 
 In marshy ground the bog-moss Sphagnum is often 
 found. This moss, during the War, was collected in 
 many parts of the country, for it forms a valuable 
 surgical dressing, better even than cotton-wool, and has 
 been largely used in the healing of wounds. The leaves 
 are a splendid example of fibre-tissue, and well illustrate 
 the development which takes place in tissue, if examined 
 day by day. 
 
CHAPTER X. 
 MARINE LIFE. 
 
 I. 
 
 IT is not all of us who are so fortunate as to live by the 
 sea ; but in normal times it is reasonable to suppose 
 that most of us may visit the seaside at some time 
 or other during our holidays. During such a visit we 
 may take the opportunity of collecting a quantity of 
 material for examination under the microscope, either 
 during some wet day of our holiday or to take home with 
 us for dealing with at leisure. 
 
 Living in sea water we find plants and animals closely 
 resembling those of fresh water. Indeed they belong to 
 the same families, although of entirely different species. 
 There are, for instance, many forms of minute seaweeds 
 which belong to the same families as the diatoms and 
 the Coniferce. The structure of the fruit-bearing organs 
 of the larger seaweeds are very interesting under the 
 microscope. A frond of " bladder-wrack " shows swollen 
 masses in certain places, covered with rough bodies of 
 yellow colour. These contain spores, which carry deli- 
 cate hairs of various forms. 
 
 104 
 
PLATE XXV 
 
SPONGES. 
 II. 
 
 105 
 
 There are also numbers of minute marine animals 
 which are of the greatest interest to us. Among the most 
 lovely forms are the sponges, which are composed of 
 animal matter combined with horn, chalky, or flinty 
 substance. This forms a network which may be seen by 
 cutting with a pair of sharp scissors a thin section from 
 a bathroom sponge (a, Fig. 37) . Other forms of sponges 
 
 FIG. 37. Sponge spicules. (a) Section of common sponge, (b) Spicu- 
 lum from fresh-water sponge, (c) Spiculum from Tetkea. (d) 
 Section of common British sponge, (e) Spiculum of (d) mag- 
 nified. (/) Pin-shaped spiculum from Cliona. 
 
 may be found with seaweed on the seashore, and these 
 show a network composed of sharp, needle-like objects, 
 or flinty spicules, as they are called (d, Fig. 37). These 
 spicules lie one over the other and differ in form and size 
 in various sponges. In fact, so pronounced and well 
 known are their differences that it soon becomes quite 
 easy to identify the species of a sponge from the shape 
 of its spicules. Some spicules are pin-headed, as in the 
 case of Cliona, a little boring sponge, found in the shells 
 
 (2,084) 14 
 
106 THE MICROSCOPE. 
 
 of old oysters (/, Fig. 37). Another well-known spicule 
 is one shaped like a delicate dumb-bell and belonging to 
 the fresh-water sponge (6, Fig. 37). Some spicules as 
 in the case of Tethea are round and covered with 
 pointed projections, reminding us of part of a mace, one 
 of the curious weapons of war in use in the olden days 
 (c, Fig. 37) . Sometimes sponge spicules are mounted along 
 with diatoms to make beautiful designs ; Plate XXI. 
 shows two of these slides. In a spicules resembling 
 minute pick-axes alternate with groups of three navicular 
 diatoms. In b the dumb-bell type of spicule is to be 
 seen, and there is also another kind, looking like a delicate 
 corkscrew, the whole forming a pleasing figure and a very 
 eloquent testimony of what patience can do in the ar- 
 ranging of microscopic objects. 
 
 III. 
 
 We must now leave the sponges and learn something of 
 another and equally interesting class of object found in 
 the sea. These are the Foraminifera, a name derived 
 from the Latin words foramen, " an aperture," and fero, 
 " to bear." The Foraminifera are simple animalcules, 
 like the Amoeba, but possessing the power to surround 
 themselves with a chalky or calcareous shell. These 
 shells have tiny holes in them, and hence their name, 
 which means " the hole-bearers." To form their shells, 
 the little creatures collect the carbonate of lime con- 
 tained in the sea water, and surround their bodies with 
 it. Some Foraminifera construct their shells of minute 
 sand grains, and these are called " tests/' Both kinds 
 of shells are almost indestructible, and, in the case of 
 
FORAMINIFERA. 107 
 
 fossil Foraminifera, have lasted through the ages. Dur- 
 ing this time they have often undergone great pressure 
 in the Earth's crust, still remaining unbroken and 
 perfect. 
 
 Foraminifera are larger in size in the waters of the 
 warmer oceans than they are in the waters of the polar 
 seas. As we have already mentioned, the shells vary 
 
 FIG. 38. Foraminifera. 
 
 greatly in design. Some (like the kind called Largena) 
 consist of a single chamber and resemble a small Indian 
 club (a, Fig. 38). Others, like Globigerina, are a cluster 
 of chambers arranged spirally (c, Fig. 38). The younger 
 Globigerina shells number from eight to twelve chambers, 
 and are thin and smooth ; but the older shells may con- 
 sist of sixteen or even more chambers, and are much 
 thicker. 
 
108 THE MICROSCOPE. 
 
 Often Foraminifera may be found alive among the 
 roots of the giant seaweeds generally found on the shore 
 after a storm. If the roots be washed, and the water 
 therefrom be allowed to stand, the Foraminifera will 
 sink to the bottom, and may then be picked out and 
 examined. 
 
 Some Foraminifera so closely resemble the nautilus, 
 that early naturalists did actually include them in the 
 same class of shell-fish. Now, however, it is well known 
 that the animal bodies of the two creatures are quite 
 distinct from each other. There is also an important 
 difference. The nautilus, although it forms chambered 
 cells, lives in the last formed chamber. It adds a larger 
 chamber when the size of its body so increases that it is 
 necessary to give more room, withdrawing from each 
 chamber in succession. The Foraminifera which so 
 closely resembles the nautilus in appearance is not a 
 single-bodied animal but has a composite body, consist- 
 ing of a number of segments connected one to the other 
 by a filament or membrane. It continues to increase 
 by " budding/' and as each new segment is formed a 
 new chamber is added to the shell. Thus unlike the 
 case of the nautilus each chamber of the Foraminifera 
 is occupied by a segment of the animal's body. 
 
 IV. 
 
 Until forty or fifty years ago very little was known 
 about the floor of the ocean. Some people knew that 
 our oceans were so deep in certain places that the depth 
 could be measured only in " miles," but that was about 
 the extent of our knowledge. Some scientists argued 
 
PLATE XXVI 
 
 ri 
 
 PQ 
 
 
 
 I 
 
 e a 
 
FORAMINIFERA. 109 
 
 that nothing could live in water so deep, where the sea 
 floor was in total darkness, and expressed the opinion 
 that the pressure of the water itself must be so great as 
 to forbid the existence of life of any kind. However, 
 a kind of net and basket called the deep-sea dredge 
 was invented, and with this the floor of the ocean 
 at its deepest places was explored. The dredge was 
 lowered from a ship, which meanwhile travelled 
 slowly along and dragged the dredge with it. The 
 dredge was then hauled to the surface and, to the wonder 
 of all, numerous delicate forms of life were found in it. 
 
 Among the multitude of interesting objects which 
 the deep-sea dredge reveals, is a light-coloured mud or 
 ooze. This ooze is nearly wholly composed of Foramin- 
 ifera shells, the largest of which are less than a pin's head 
 in size. The celebrated German naturalist Ehrenberg 
 estimated that one cubic inch of ooze contained over 
 1,000,000 of these shells. They are of all manner of 
 shapes, some having one chamber, others several. There 
 are straight shells, curved shells, flat shells, round shells, 
 coiled shells, and oblong shells. Some are white and 
 chalky looking, others resemble pearls, and others, yet 
 again, are clear and transparent like glass. All the shells 
 from the ocean floor are empty, for they are shell-cases 
 only. If we scoop up some of the tiny shells which 
 float on the surface of the ocean and in its waters, how- 
 ever, we find they have living creatures inside. 
 
 Foraminifera are found in greatest numbers in mud 
 or ooze dredged up from the bed of the Atlantic, but 
 many varieties may be obtained from the sands around 
 our own coasts. They also live in rock pools or attached 
 
no THE MICROSCOPE. 
 
 to seaweeds. If placed under the microscope in some 
 sea water, the curious action of the pseudopods may be 
 seen. When the shells are to be mounted on slides they 
 must first be boiled in a strong solution of potash ; this 
 destroys their animal contents, but does not injure the 
 shell. The shells may also be obtained from chalk 
 cliffs and separated by placing the chalk in water until 
 softened. 
 
 Foraminifera are divided into two groups, called 
 Imperforata and Perforate In the former group are 
 classed those shells which have one main opening (or 
 sometimes more), and in the latter group the shells 
 which, in addition to the main opening, have perfora- 
 tions through the walls. 
 
 V. 
 
 No doubt many of you have seen the chalk deposits 
 in one part or another of our Island. On the east coast 
 of Yorkshire, at Bempton and Flamborough, the cliffs 
 are several hundred feet high. The chalk cliffs near 
 Dover are known to the sailors as " the white walls of 
 old England." London is built on chalk, as is also 
 Paris; and similar rocks to these are found extending 
 over France, Denmark, and Central Europe. They 
 reach also from Northern Africa to the Crimea, and from 
 Syria to the Sea of Aral in Central Asia. 
 
 All these chalk deposits consist largely of the remains 
 of Foraminifera shells. When their inhabitants die, the 
 shells sink to the bottom of the ocean, and there form 
 the fine mud or ooze to which we have already referred. 
 The shells are always falling, as lightly as motes in a 
 
FORAMINIFERA. in 
 
 sunbeam, sometimes through thousands of feet of ocean 
 depth. It is just as if a continuous snowstorm was 
 taking place in the sea, the flakes of which are just 
 as beautiful when seen in the microscope as are snow- 
 flakes when similarly viewed. 
 
 This rain of shells is going on at the present time, 
 and exactly the same happened ages ago. Far back in 
 the Earth's history countless millions of these shells 
 fell day and night, century after century. Foraminifera 
 inhabited the prehistoric oceans, just as their descendants 
 live in our seas to-day. Every drop of water was alive 
 with them, and they were so numerous that the floors of 
 the oceans in which they lived soon became covered 
 with their shells. As they continued to fall, so did their 
 shells continue to accumulate, until after the passing 
 of many millions of years, perhaps they formed the 
 chalk deposits which we know to-day. These deposits 
 of chalk are called by geologists the cretaceous rocks, 
 from the Latin word creta, which means " chalk." The 
 deposits have been lifted high above the level at which 
 they were formed by Earth movements, and they show 
 us that in times gone by there must have existed great 
 seas where they occur. For instance, the cretaceous 
 rocks tells us that at one time South-East England, 
 France, Germany, Poland, Russia, Egypt, Arabia, and 
 Syria were all under the sea. 
 
 The stone of the Pyramids consists of the fossil shells 
 of a variety of Foraminifera called nummulites (Latin 
 nummulus, " a small coin "), a species which, as its name 
 implies, is coin-like in shape. 
 
112 THE MICROSCOPE. 
 
 VI. 
 
 Among the most; beautiful objects which the microscope 
 can show are the Polycystina, a group of Radiolaria 
 (Plate XXII.). The name is derived from the Greek 
 polus, " many," and kustis, " a cyst or box." They are 
 of all shapes, and are covered with minute perforations 
 through which the creature inside could thrust its 
 pseudopodia and capture food, or propel itself through the 
 water. If a, Plate XXIII., be examined with a magni- 
 fying glass, some of the more common varieties may be 
 seen. When seen on a dark background Polycystina 
 look like miniature jewels. They are obtained from the 
 chalky-looking Barbadoes earth, which is sometimes used 
 for polishing purposes. 
 
 VII. 
 
 Another interesting animal which lives in the sea is 
 Noctiluca miliaris, a name which means " thousands of 
 nightlights." To this minute animal is due the peculiar 
 phosphorescent appearance often seen in the sea. De- 
 scribing the phenomenon Darwin, in his famous book, 
 The Voyage of the 'Beagle, says : " While sailing a 
 little south of the Plata on one very dark night, the sea 
 presented a very wonderful and very beautiful spectacle. 
 There was a fresh breeze, and every part of the surface 
 which, during the day, is seen as foam, now glowed with 
 a pale light. The vessel drove before her bows two 
 billows of liquid phosphorus, and in her wake she was 
 followed by a milky train." 
 
 Another writer has described the phenomenon as 
 
PLATE XXVI I 
 
 HE E DIE fotNT 
 
 From photo-micrographs by] 
 
 (C) 
 
 (Ellison Hawks 
 
 (a) WING OF BEE. (b) STING OF WASP. (c) STING OF BEE 
 AND NEEDLE COMPARED 
 
" THOUSANDS OF NIGHT-LIGHTS." 113 
 
 follows : "In certain oceans and seas, in calm weather, 
 when the nights are dark, the wake of the passing ship 
 resembles a path of oscillating gold, increasing in bril- 
 liancy until it glistens in whiteness. The contrast with 
 the surrounding black waters becomes most impressive. 
 The boatman puts off from the shore, and as he dips his 
 oars and lifts them up the dripping waters sparkle as if 
 illuminated by thousands of microscopic arc-lamps, while 
 the prow of his boat cuts its way through liquid bril- 
 liants. A gentle ripple is sufficient at certain times to 
 cause the luminosity to appear, but when the sea is 
 absolutely smooth there is no observable display." 
 
 The peculiar phosphorescent light which Noctili4ca 
 miliaris emits may be seen even when only a com- 
 paratively small number of the creatures are contained 
 in a jar. If the >ar be gently shaken, or knocked, the 
 little captives instantly emit a soft light, of a beautiful 
 greenish hue. This is strong enough to be seen even by 
 lamplight. It only lasts for an instant, however, and 
 the animals require a short rest before it can be renewed. 
 
 Noctiluca miliaris belongs to a group of the Protozoa, 
 and is about F V inch in diameter. It can just be seen 
 by the naked eye if the water in which it is contained 
 is held up to the light. With a hand magnifying glass 
 its flagellum, or tail-like appendage, is visible. Flagellum 
 is a Latin word meaning " a little whip," and the presence 
 of this feature dis-.inguishes that group of Protozoa to 
 which Noctiluca miliaris belongs, from the group of 
 which Amoeba is a typical example. Flagella are long, 
 slender filaments, usually few in number, and are used 
 both for obtaining food and for moving about through 
 
 (2,084) 1 
 
H 4 THE MICROSCOPE. 
 
 the water. The former is accomplished by vibrating 
 the ftagella, which sets up currents and whirlpools ; 
 particles of food are thus drawn to the animal's mouth. 
 The motion of the animal through the water is accom- 
 plished by a peculiar lashing movement, which causes 
 the animal to be dragged along in jerks or leaps. 
 
CHAPTER XI. 
 
 AN INSECT LABORATORY AND WORKSHOP: 
 THE HONEY-BEE. 
 
 I. 
 
 IN this little book we have not sufficient space to 
 learn everything about the many kinds of insects 
 and their varying appearances in the microscope. In- 
 stead, I intend to tell you a little about only one insect, 
 so that you may learn from it something of what applies 
 to all insects generally. The insect which I have chosen 
 for the purpose is Apis mellifica, the honey-bee, because 
 not only is it well known to all, and sufficiently common 
 for specimens to be easily obtained, but it is one of the 
 most interesting of all the members of the insect world. 
 
 We cannot here consider the wonderful story of hive- 
 life that has already been told in another volume of 
 the series to which this book belongs.* In these pages 
 we are more concerned with the aspect of the bee as 
 shown by the microscope, and with an examination of the 
 wonderful limbs and the parts of its body which enable 
 it to turn nectar into honey, and to manufacture the 
 wax required for the comb. We must see something also 
 
 * Bees : Shown to the Children. By Ellison Hawks. 
 115 
 
n6 THE MICROSCOPE. 
 
 of the tools with which it collects the pollen, builds the 
 cells, and accomplishes the numerous other processes 
 required of it in its daily life. 
 
 II. 
 
 The bee is a typical insect, having head, thorax, and 
 abdomen. The head is something like half a split pea 
 in shape, with the rounded part turned to the front, and 
 is joined to the thorax by a thin neck. There are five 
 eyes, two compound and three simple, and it will be as 
 well if we note here the -difference between the two types 
 of eyes. Spiders possess only simple eyes, but the bee 
 has both compound and simple, as I have mentioned. 
 In the case of the bee, the compound eyes are placed 
 one on each side of the head, and are large and prominent, 
 like those of the house-fly. The simple eyes are to be 
 found at the top of the head, and are hidden away in the 
 fine golden hairs with which the head is covered (a, 
 Plate XXIV.). The compound eyes are of a deep, 
 purplish colour, and glisten like satin. They are made 
 up of a multitude of hexagonal, or six-sided, cells similar 
 in shape to those of the honeycomb. These cells are 
 called facets, which means little " windows," and each 
 one measures about ^-^ part of an inch in diameter. 
 Each facet is really a small eye in itself, and that is the 
 reason the eyes are called compound. In the eye of 
 the worker bee there are over 6,000 facets, each one 
 pointing in a slightly different direction. Large though 
 this number appears to be, it is less than half the number 
 possessed by the drone, whose facets number 13,000 in 
 each eye. The queen-bee has about 5,000. 
 
PLATE XXVIII 
 
 
 Froai photo-micrographs by) (fo) 
 
 HOOKS ON WING OF BE! 
 (a) Unlocked. (b) Locked 
 
 lEllison Hawks 
 
THE EYES OF THE BEE. 117 
 
 Each facet acts as a minute lens. With a camera 
 a photograph may be taken of any object at which it 
 is pointed, for the lens with which it is fitted throws an 
 image of the object on the photographic plate. Our 
 own eyes act as lenses, and throw an image of whatever 
 we look at, not upon a photographic plate, but upon a 
 sensitive surface called the retina, a Latin word meaning 
 " a small net." The retina catches the picture from the 
 crystalline lens of our eye and passes it on to the brain, 
 where we " translate " it, as it were, and understand it. 
 Each facet in the compound eye acts as a minute lens. 
 At one time it was believed that each facet made a 
 separate image of the object at which it was directed, 
 but this is not now generally believed to be the fact. 
 It is realized that it is unlikely that Nature would provide 
 an eye to show several thousands of flowers instead of 
 the one at which the eye was directed. It seems much 
 more probable that each facet forms an image of only 
 that part of the object which is exactly in front of it, all 
 the pictures combining to form a single image, just as 
 the small coloured bricks in a mosaic work combine to 
 form a pattern. 
 
 The simple eyes are arranged so as to form a triangle, 
 like this v In the case of the drone the compound 
 eyes are so large that they extend not only over all the 
 space at the side of his head but also right over the top, 
 covering the position occupied by the simple eyes in the 
 worker. On account of this the drone's simple eyes are 
 placed lower down on the front of his head, the position 
 approximating more to that of our own eyes. 
 
 The simple eyes are so called because they do not seem 
 
H8 THE MICROSCOPE. 
 
 to be nearly so complicated in their construction as the 
 compound eyes, but nevertheless they have an elaborate 
 structure. 
 
 Over the surface of the compound eye are distributed 
 numerous long, straight hairs. Their chief purpose is 
 to protect the facets, just as the eyelashes of our own 
 eyes protect them. The simple eyes have tufts of hair, 
 like eyebrows, surrounding them, but these are so placed 
 that they do not interfere with the range of vision. 
 Bees have no eyelids as we have, so they have to rely 
 upon these hairs to protect their eyes from dust and other 
 foreign bodies. 
 
 III. 
 
 In addition to the eyes, the head carries the antenna, 
 or " feelers," as they are commonly called. The antenna 
 of the worker bee each consists of a single long joint and 
 eleven small joints (b, Plate XXV.). The long joint is 
 called the " scape," meaning a shaft or stem, and the 
 smaller ones are said to form the flagellum, which, as 
 we have already seen, means " a little whip." The 
 antenna of the drone, whilst resembling those of the 
 worker, have one more small joint in the flagellum, 
 thus making the total number twelve. They are fixed 
 to the bee's head by a cup-and-ball joint, and can be 
 moved in practically any direction. In addition, each 
 of the joints of the flagellum can be moved separately. 
 
 The scape is covered with numerous hairs, which are 
 both long and fine. The first three joints of the flagellum 
 are also covered with hairs which, however, differ in 
 appearance from those of the scape, being much shorter 
 
THE ANTENNA OF THE BEE. 119 
 
 and thicker. They look more like bristles, and all point 
 in a downward direction. The remaining eight joints 
 are covered with multitudes of still smaller hairs, and 
 these again differ in their construction. The hairs on 
 the antenna of a drone number about 4,000, and on 
 those of a worker about 28,000. Each hair is connected 
 with a nerve so sensitive that the most delicate touch 
 can be perceived immediately. 
 
 The antenna serve many useful purposes, and are of 
 a wonderful and complicated structure. In the hive, 
 although it is dark, the bees are able to find their way 
 about by means of them. They build their combs with 
 their aid, and with them they communicate with each 
 other. Watch bees on the alighting board of a hive, 
 how they approach and gently cross their antenna, as 
 two duellists cross their swords before a fight. For a 
 fraction of a second one seems to lightly tap the antenna 
 of the other, and it is obvious that a communication is 
 passing between them. 
 
 In the antenna are the nerves with which bees smell. 
 The " smell hollows," as they are called, are exceedingly 
 numerous and minute. Each of the last eight joints of 
 some worker bee's antenna have fifteen rows of twenty 
 " smell hollows," a total of over 2,400 in each antenna. 
 The queen has only about 1,600, but the drone has 
 37,000 on each antenna. 
 
 Here also are found the ears of the bee. We generally 
 expect to find the ears of living creatures in their heads, 
 but Nature sometimes plays queer tricks in the animal 
 world. For instance, who would dream of looking for 
 the ears of a cricket in its legs ? Those of the grass- 
 
120 THE MICROSCOPE. 
 
 hopper are found in a similar place. Then there is a 
 kind of shrimp, called the Mysis, which actually has its 
 hearing apparatus in its tail ! Thus, when we remember 
 these peculiarities it is perhaps not quite so strange as 
 it at first seemed to find the bee's ears in its antenna. 
 The ears take the form of oval-shaped holes or depressions, 
 and are quite distinct from the " smell hollows " already 
 mentioned. They measure only about T^j-J^ P ar t of 
 an inch in size, and each is surrounded by a minute ring 
 of bright orange colour. 
 
 The central part of the antenna is hollow and contains 
 the nerves which run like a bundle of electric cables to 
 the ganglia. Ganglia comes from the Greek and means 
 " a knot," and it is really a knot or a bunch of nerves, 
 for they are the " nerve centres " situated in the body. 
 The chief ganglion is in the head, and corresponds to the 
 brain in animals. Other ganglia are found in the thorax 
 and in the abdomen. 
 
 IV. 
 
 The tongue of an insect is called the proboscis, a Greek 
 word meaning a " front feeder or trunk," and indeed the 
 bee's tongue is not unlike the trunk of an elephant in 
 appearance. The tongue itself is long and tapering, and 
 is composed of a number of ring-like structures, covered 
 with hairs, arranged in a regular manner, and pointing in 
 a downward direction (b, Plate XXIV.). In the tongue of 
 the queen and drone the rows of hairs number from sixty 
 to sixty-five, but in the case of a worker, which has a much 
 longer tongue, they number ninety, to a hundred rows. 
 Some of these hairs are used for feeling, but most of them 
 
PLATE XXIX 
 
 POISON BAG 
 
 
THE THORAX OF THE BEE. 121 
 
 are necessary for collecting the nectar from the flowers. 
 This adheres to the hairs when the bee pushes its head into 
 the corolla and sweeps from side to side with its tongue. 
 The tongue is extremely flexible and can be moved in 
 any direction. At the extreme end is the spoon, also 
 used in collecting nectar, and covered with delicate 
 branched hairs (b, Plate XXIV.). The front is composed 
 of maxilla, or inner jaws. The tongue, but not the pro- 
 tecting tube, can be drawn up into the bee's mouth at 
 will. The labial palpi each consist of four joints, of 
 which the two nearest the mouth are the largest. They 
 also have numerous hairs, used for feeling as well as pro- 
 tection. 
 
 The maxilla, or inner jaws, have already been men- 
 tioned. The outer jaws are very hard and have sharpened 
 edges. The action of most insects' jaws resembles a pair 
 of scissors in opening and closing. Those of the bee are 
 very powerful and are chiefly used in the making of honey- 
 comb, the wax of which is thinned out by their aid. 
 
 V. 
 
 The thorax, or chest, of an insect may be likened to the 
 engine-room of a ship, for it is the centre of all movement 
 so far as the wings and legs are concerned. It is divided 
 into three parts : the pro-thorax or forward division near- 
 est the head, the meso-thorax or middle division, and the 
 meta-thorax or after division. It contains several large 
 muscles, for the bee is a powerful flier, and is thickly 
 covered with fine, downy hairs. Among these hairs are 
 a number of other spike-like hairs, in which pollen is 
 entangled when the bee enters a flower. 
 
 (2,084) 16 
 
122 THE MICROSCOPE. 
 
 The thorax also contains the trachea, or air sacs. These 
 fill with air and make the body more buoyant, and thus 
 assist the flight of the insect. 
 
 VI. 
 
 The legs of the bee are very interesting, and nearly every 
 microscopist is sure to have slides of them, for they are 
 well known as " show objects/' There are, of course, three 
 pairs of legs, one pair being attached to each division of 
 the thorax. Each leg has nine joints and terminates in 
 two claws and a kind of soft pad (c, Plate XXVI.). The 
 claws are used in walking over rough surfaces, and when 
 wax-making the bees hang in chains or festoons from the 
 
 CLAW** PAD 
 
 FIG. 39. The claw and pad. 
 
 roof of the hive by hooking their feet together. The soft 
 pad is called the pulvillus and is used for walking on a 
 smooth surface or in positions in which the claws cannot 
 be used. When the claws fail to grip any surface they 
 slide down under the foot, and the pad is thus automatic- 
 ally brought into action, for it presses against the smooth 
 surface and adheres to it by means of the viscid moisture 
 with which it is covered (Fig. 39). 
 The legs nearest the head are the shortest pair, and 
 
A BEE'S BRUSH AND COMB. 
 
 123 
 
 their most interesting features are the brushes and comb 
 (Fig. 40). The brushes consist of hairs which serve two 
 purposes, one for cleaning the comb and the other for 
 freeing the hairs of the eye of pollen and dust. The 
 comb is a semi-circular notch around which are arranged 
 
 FIG. 40. The brush and comb. 
 
 about eighty teeth. Just above is the vellum, a kind of 
 hinge or lid, and so named because it " covers " the 
 antenna when it is drawn into the comb and holds it 
 there whilst it is being pulled through. This operation 
 is performed by the bee bringing its front leg to its head 
 and then moving the leg outwards. By this movement 
 
124 
 
 THE MICROSCOPE. 
 
 the antenna is drawn into and through the comb, the 
 teeth removing any dirt and pollen which may be adher- 
 ing to it. 
 
 The second pair of legs have a kind of stiff spike used 
 for cleaning the wings. The hindermost pair are the 
 longest, and are furnished with wax-pincers consisting 
 of a row of spikes at the joint (a, Plate XXVI., and 
 c, Plate XXIX.). The corbicula, or pollen basket, is 
 also found in the hindermost legs. In it pollen is carried 
 from the flowers to the hive. The large joints, or thighs 
 as it were, of this pair of legs are much broader than the 
 corresponding joints in the other legs. 
 They are also hollowed out and are fur- 
 nished at the edges with spikelike hairs, 
 which curve inwards over the hollow 
 (Fig. 41). This is on the outside of the 
 leg, and on the inside are several combs, 
 made up of rows of hairs. When the 
 thorax is covered with pollen it is combed 
 out by means of these hairs by the bee 
 crossing its legs beneath its body. The 
 pollen is then fashioned into a little 
 ball or pellet and passed into the pollen 
 basket, where it is held until the bee 
 reaches the hive. Pollen is mixed with 
 honey to make " bee-bread." This is 
 food for the young bees. 
 
 FIG. 41. Pollen 
 basket. 
 
 VII. 
 
 Bees belong to the Hymenoptera order of insects, and 
 have four wings a pair of large and a pair of small, 
 
PLATE XXX 
 
 
 (a) 
 
 From photo-inicrojjraphs by] 
 
 Co) 
 
 [K. Cuzner, KK.M.S. 
 
 SPIRACLES OF DYTISCUS 
 
 (a) Showing the spiracles on the side of the Water-Beetle, (b) A highly 
 magnified spiracle 
 
THE WINGS OF THE BEE. 125 
 
 called respectively the anterior and the posterior. The 
 name is derived from the Greek words hymen, " marriage," 
 and pteron, " a wing," and thus means " married wings." 
 The hymenoptera are so called because the upper and 
 under wings on each side of the body are " wedded " or 
 linked together when the insect is flying by a row of hooks 
 and a ledge, a device which is more fully explained in 
 the next paragraph. Like the legs, the wings are 
 joined to the thorax; they are composed of fine mem- 
 branes and are strengthened by a kind of framework. 
 The ribs of this are called the nervures (a, Plate XXVII.) 
 and are hollow ; like our veins they contain blood. 
 
 Along the top edge of the lower whig is a row of tiny 
 hooks, while the lower edge of the upper whig is curled 
 over, forming a kind of ridge (a, Plate XXVIII. ). There 
 is thus formed a " hook and eye " by which the two wings 
 are locked together for flight (6, Plate XXVIII.) . By 
 these means a large parr of wings is formed which are 
 more powerful for flying than would be the case if the 
 bee had only two small pairs of wings with no inter- 
 locking device. The bluebottle fly has only one pair 
 of large wings, but this arrangement would not be prac- 
 ticable in the case of the bee. If its wings were not 
 divided the worker bee would be unable to crawl into 
 the nursery cells to clean them out. These cells measure 
 inch in diameter. When the wings are folded over the 
 bee's back they take up only inch. There is thus just 
 sufficient space for the bee to enter the cell. The blue- 
 bottle does not need to fold its wings closely over its 
 back, for it has no cells to clean. 
 
 The action of the hook and eye is almost automatic, 
 
126 THE MICROSCOPE. 
 
 for when the bee takes to flight the front wing is stretched 
 out from over its back, and in this operation it passes over 
 the upper surface of the back wing. On the ridge reach- 
 ing the hooks it catches upon them and is held fast. 
 When the bee comes to rest the process is reversed, 
 for as the wings are folded the ridge slips away from the 
 hooks that hold it. 
 
 The number of hooks varies, and sometimes more are 
 found on one side of the body than the other. As a 
 general rule the worker bee has from eighteen to twenty- 
 three. The queen, who seldom flies, has not so many 
 sometimes as few as thirteen. The drone has large and 
 powerful wings, and the number of his hooks varies 
 between twenty-one and twenty-six. 
 
 VIII. 
 
 The abdomen, containing the stomach and intestines, 
 is joined to the thorax by a thin waist. The abdomen 
 of the queen and of the worker is divided into six rings 
 or segments, but the drone, having a somewhat larger 
 body, has seven. Each segment itself is divided into 
 two parts, known as the scelentes, and joined to one 
 another by a delicate membrane. 
 
 The bee has two stomachs, the honey-sac and the 
 stomach proper. The honey-sac is a kind of store cham- 
 ber in which the nectar is kept after it has been gathered 
 from the flower, until the bees return to the hive. Lead- 
 ing from it to the stomach is a very fine tube or duct, 
 at the end of which is a kind of stopper or valve, called 
 the " stomach mouth/' By opening or closing this the 
 supply of food to the stomach may be regulated. The 
 
THE BEE'S STOMACH. 127 
 
 honey-sac is relatively minute, and even when quite full 
 contains only about one-third of an ordinary sized drop 
 of honey. 
 
 The tube which leads from it to the stomach is lined 
 with minute hairs, very fine and pointing in a direction 
 away from the honey-sac. When nectar is taken in from 
 a flower, pollen grains may be unavoidably taken in also. 
 This is undesirable, and so the nectar is passed from the 
 honey-sac to the stomach by means of the tube. The 
 nectar is then made to return to the honey-sac, and in 
 this operation the hairs in the tube act as a strainer and 
 prevent the pollen grains returning with the nectar. 
 This operation is carried on while the bee is flying from 
 flower to flower or on the way back to the hive. 
 
 Bees do not actually collect what is called honey, but 
 they gather what the flowers secrete. This is nectar, 
 which may be described as a thin watery liquid, contain- 
 ing among other things a large proportion of cane sugar. 
 The honey-sac is filled with nectar gathered from flower 
 after flower, and while the bee flies a change takes place 
 in the nectar, and it becomes converted into honey. 
 Some juices secreted by glands in the abdomen are added 
 to it and the cane sugar is changed into another form, 
 called grape sugar. 
 
 IX. 
 
 Insects breathe through tiny air-holes called "spiracles," 
 from the Latin spirare, " to breathe " (Plate XXX.). 
 Crawling insects do not require so much air as flying 
 insects, and their breathing apparatus is therefore not so 
 large. In a bee the breathing tubes spread over almost 
 
128 THE MICROSCOPE. 
 
 the whole body, two of the largest extending along each 
 side of the abdomen. These air tubes branch off one 
 from another like the roots of a tree. The majority are 
 exceedingly minute, a bundle of a quarter of a million 
 being required, it is estimated, to equal in size a human 
 hair. The rings of the abdomen slightly overlap one 
 another, and as the bee draws in and then drives out the 
 air, in the act of breathing, these rings constantly slip 
 in and out. The spiracles are protected by a number of 
 tiny hairs which keep out dust and other foreign bodies 
 which would interfere with the breathing. 
 
 X. 
 
 The sting is situated at the tip of the abdomen and con- 
 sists of several parts. The sting itself is very smooth 
 and hard, and terminates in a delicate, lance-like point, 
 compared with which an ordinary fine sewing needle 
 looks like a bar of iron (c, Plate XXVII.). This sting 
 is really a sheath, in which are enclosed two needle-like 
 darts. On the outside of the sheath at the end are two 
 rows of three, or sometimes more, barbs pointing back- 
 wards. These prevent the sheath slipping out of the 
 flesh into which it has been forced, until the operation 
 of stinging is completed. The darts in the sheath can 
 be moved up and down by a powerful set of muscles at 
 the root of the sting. They act like drills, and come into 
 play as soon as the sheath has made an opening for them. 
 They move up and down at a great speed, piercing deeper 
 and deeper into the flesh of the victim each time. They, 
 too, have barbs (b, Plate XXVII.), and near each barb 
 is a minute hole leading to a central hollow in the dart. 
 
PLATE XX XT 
 
 Fr>m a water-colour drawing by] 
 
 [G. 1-ishcr-Jones 
 
 () Part of a Butterfly's wing. () Scales from the Diamond Beetle. 
 (c) Feather from Humming Bird. 
 
THE BEE'S STING. 129 
 
 Down this hollow and through the holes in the dart- 
 barbs a poisonous fluid is poured which causes the pain 
 of a sting. The poison is composed largely of formic 
 acid, and is secreted in a poison-bag near the root of the 
 sting (a, Plate XXIX.). It is forced down the central 
 hollow of the darts by two muscles acting as pumps. 
 The sting of a worker bee is quite straight, but that of 
 the queen is curved .like a scimitar. The drone has 
 no sting. 
 
 (2,084) 17 
 
CHAPTER XII. 
 
 OTHER INSECTS. 
 
 I. 
 
 AS in the case of plants, insects are full of interest 
 JLjL to the microscopist ; even the most common will 
 reveal points of interest when seen under the microscope, 
 and they will furnish unlimited material for months of 
 study during the long nights of winter. Specimens 
 should be collected during the summer, and may be 
 preserved in weak acetic acid for a very long time, for 
 examination at leisure. They may then be studied just 
 as they are, or if desired may be dissected, their internal 
 organs examined, and further interest added by mounting 
 all the parts on a card, neatly numbering and naming 
 them. Butterflies, spiders, flies, beetles, wasps, fleas, 
 ants, and the like, all are worthy of attention. 
 
 There is so much of interest that it is, of course, quite 
 impossible to describe fully even a fraction of the objects. 
 I can only mention a few, and those very briefly, so that 
 you may have an idea of what a wonderful storehouse of 
 interest awaits you. 
 
 Insects are sometimes divided into two groups, which 
 
INSECT "FRIENDS" AND "ENEMIES." 131 
 
 are called " friends " and " enemies." This distinction 
 is not, of course, a scientific one, but it may serve as 
 a guide and be of assistance to the memory to know 
 whether a certain insect is helpful or not to us. It is 
 very necessary that we should learn all we can about the 
 habits and life-history of the insects we are studying 
 before classifying them as friends or enemies, because 
 otherwise we might easily make a mistake. For instance, 
 a person who has just been stung by a bee will probably 
 be quite convinced that bees should be included among 
 the " enemy " insects. On the other hand, the bee-keeper 
 will show his hives and dozens of beautifully sealed 
 sections of honey he has obtained from each hive. He 
 will tell you that to say bees should be classed as enemy 
 insects, just because they can sting and hurt, is ridiculous. 
 
 Among useful insects may be classed those which fer- 
 tilize flowers and those which give us honey, silk, dyes, 
 and medicines. In the other group fall the insects which 
 destroy clothing, food, and similar materials, and also 
 those which spread disease. The study of insects, or 
 entomology as it is called, is indeed a fascinating one, 
 and one which presents a very wide field, for in Great 
 Britain alone there are tens of thousands of varieties of 
 insects. It is a study in which there are endless problems, 
 for sometimes the habits of association of the little crea' 
 tures and the exhibitions of their wonderful instinct 
 seem almost human. 
 
 Insects may be classified according to the manner in 
 which they feed either by biting or sucking or by the 
 presence or absence of wings. In the latter method the 
 following groups are commonly recognized : 
 
132 
 
 THE MICROSCOPE. 
 
 Classification. 
 
 Characteristic. 
 
 Example. 
 
 Aphaniptem 
 Coleoptera 
 Lepidoptera 
 Diptera 
 Orthoptera 
 Neuroptera 
 Hymenoptero, 
 Thysanoptera 
 Homoptera 
 Hekeroptera 
 
 wingless 
 sheath-winged 
 scale-winged 
 two-winged 
 straight-winged 
 nerve- winged 
 membrane- winged 
 tassel-winged 
 similar-winged 
 dissimilar- winged 
 
 Fleas 
 Beetles 
 Butterflies 
 Flies 
 Grasshoppers 
 Dragon-flies 
 Bees 
 Thrips 
 Aphides 
 Bugs 
 
 II. 
 
 The Drone Fly (Eristalis tenax) very closely resembles 
 a bee, and may easily be mistaken for one when on the 
 wing. It has a wonderful foot like a double claw, and 
 with this contrivance it is able to grasp very firmly any 
 object to which it wishes to cling. This is the reason it is 
 called tenax, because this word is derived from the Latin 
 meaning " to hold." Its larvae inhabit filth and mud, 
 devouring garbage and acting as scavengers. In these 
 surroundings breathing is often difficult, so Nature has 
 fitted the larvae with long, telescopic tails, through which 
 they can breathe. 
 
 The tongue of the drone fly is split up a little way, and 
 then again joined, and the mouth parts are converted into 
 lancet-shaped organs. Not only are these darts, with 
 which the skin of animals is pierced, but they also act 
 as tubes through which their blood may be sucked up. 
 Another part of this insect's mouth resembles in appear- 
 ance a two-edged sword, while yet another has pincer-like 
 cutting teeth at its extremity. It is a peculiar tool and 
 
PLATE XXXII 
 
THE ICHNEUMON FLY. 133 
 
 resembles an instrument used by a surgeon to enlarge 
 a wound. It is actually used for this same purpose by 
 the fly, so that the flow of blood may be increased. 
 
 III. 
 
 The Ichneumon fly helps to keep down caterpillars. The 
 caterpillar pest of 1917 and 1918 was attributed by some 
 naturalists partly to the fact that one cause and another 
 had killed off. the Ichneumon flies. The caterpillars had 
 thus obtained the upper hand, as it were, and multiplied 
 so profusely as to become a serious menace to fruit- 
 growers and farmers. The Ichneumon is equipped with 
 a sharp ovipositor, or egg-laying appendage. With this 
 it pierces the skin of the caterpillar and deposits its 
 minute eggs in the caterpillar's body. It is believed that 
 the caterpillar does not feel the operation, for it will even 
 go on eating while it is being performed. Later the eggs 
 hatch out into tiny grubs which feed on the fatty sub- 
 stances in the caterpillar's body. When the caterpillar 
 has finished eating and is ready to turn into a chrysalis, 
 the young Ichneumon grubs leave it and spin them- 
 selves bright yellow cocoons. The caterpillar not having 
 any store of fat to draw upon during its chrysalis state, 
 shrivels up and dies from lack of nutriment. 
 
 IV. 
 
 Like bees, ants may be either social or solitary insects. 
 That is to say, some species live in colonies, as do bees 
 in a hive, while others live by themselves, like the mason 
 bee, building their own little nests and leading a solitary 
 life. Those ants which live in colonies again resemble 
 
134 THE MICROSCOPE. 
 
 bees, there being a queen, males, and workers. The 
 commoner kind are the Formicida, the queen and males 
 of which sometimes have wings. This causes them to be 
 mistaken by some people for flies. Under the microscope 
 the ant is seen to have two large compound eyes, and 
 three simple eyes in front, like the bee. Some workers 
 are without eyes. The antenna are many jointed, and 
 the jaws sometimes larger than the head itself. Some 
 ants have minute sets of teeth, arranged like the edge 
 of a saw. 
 
 V. 
 
 The aphis, more commonly known as the " green-fly," 
 which often infests rose-trees, is a curious insect, as seen 
 under the microscope. It is sometimes called the plant 
 lice and has a beak-like mouth. With this it pierces the 
 tender shoots of a plant and sucks up the sap, thus 
 causing the plant to be damaged and sometimes killed. 
 The sap is partly given out again by the insect through 
 two protuberances on its hinder part. Ants know of 
 this fact and they domesticate aphides, keeping them 
 as we do cows, for the sake of the sweet fluid they exude. 
 This fluid, called honey-dew, is obtained from the aphides 
 by " milking," a process in their case which consists of 
 the ants stroking them tenderly with their antenna. 
 
 Aphides are reproduced at an alarming rate. It has 
 been calculated that the descendants or progeny of a 
 single aphis in one summer will number a quint illion. 
 At this rate the Earth would very soon become a mass of 
 aphides, if it were not for the fact that they are food for 
 many other insects. The larvae of the " lady-bird " 
 
A BUTTERFLY'S WING. 135 
 
 eat great quantities of aphides, for instance, and this helps 
 to keep the pest in check. 
 
 VI. 
 
 Butterflies and moths are very beautiful objects in 
 the microscope, and among them may be found some of 
 the most lovely sights revealed to us. The colours of 
 their wings, beautiful as they are to the naked eye, are 
 enhanced a hundred-fold even with a low power, and no 
 pen can adequately describe their beauty. The wings 
 are composed of membranes, covered with thousands 
 of tiny scales, and thus it is that these insects belong to 
 the order of Lepidoptem, for the word lepis means " a 
 scale/' These minute scales form the dust which is left 
 on our fingers should we take hold of a butterfly's wing. 
 If a little of this dust be shaken on to a slip of glass and 
 placed under the microscope the scales will be clearly seen. 
 Each scale is held to the wing by a tiny root. The scales 
 lie upon the wing membrane in rows, overlapping each 
 other like the slates on the roof of a house, and they pro 
 tect the delicate membrane against dew and rain. 
 
 In a, Plate XXXI., is shown a portion about T V inch 
 diameter of a tiny white dot in the " eye-spot " of the 
 fore-wing of a Peacock butterfly (Vanessa io). The 
 scales of butterflies are actually coloured, and therefore 
 differ from the scales of some insects, which are iridescent, 
 or rainbow-hued. To this latter class belong the scales 
 of the small Diamond Beetle (Curculis imperialis) shown 
 at b, Plate XXXI., which owe their colour to their ex- 
 treme thinness and their transparency, as in the case of 
 the soap-bubble or oil on water. There is still another 
 
136 THE MICROSCOPE. 
 
 class of scales which glow with colour caused by the 
 breaking-up of white light by numerous extremely narrow 
 lines or furrows with which their surface is covered. A 
 very good example of this type is afforded by the minute 
 brilliant feathers in the breast of a Humming Bird (c, 
 Plate XXXI.). Those of you who are interested in the 
 explanation of this beautiful iridescent colouring may 
 pursue the matter farther by studying some book on 
 Light, which deals with the interference of light caused 
 by thin films and with diffraction caused by fine surface 
 rulings or striated sui faces. 
 
 VII. 
 
 The proboscis or tongue of the butterfly often reaches 
 an enormous length in some species. By its aid the insect 
 is able to reach deep down into the corollas of flowers 
 to extract the nectar secreted there. When not in use 
 the tongue is curled up like the hair-spring of a watch. 
 
 We have already seen how flowers are fertilized by 
 insects, and how important it is that the pollen should be 
 carried to the stigma. Much of this work of fertilization 
 is done by bees, but there are some flowers which bees 
 cannot fertilize, owing to the shape of their corollas. 
 Honeysuckle and convolvulus, for instance, have" corollas 
 so long that the bee's tongue cannot possibly reach the 
 nectar stored at the base. Flowers such as these depend 
 on butterflies and moths for their fertilization, so we find 
 that these insects are provided with exceptionally long 
 tongues. As moths fly by night, it is then that the 
 flowers which wish to attract them put out their choicest 
 perfumes, for the sweet smell guides the moths to them. 
 
PLATE XXXIII 
 
 From a photo-micrograph by] 
 
 THE TONGUE OF A BLOW-PLY 
 
 [A. E. Smith 
 
THE SILKWORM. 137 
 
 VIII. 
 
 Among the useful insects must be included the silk- 
 worm (Bombyx mori). No doubt many of you have kept 
 silkworms, and studied their interesting habits. You 
 will therefore know that this insect is not a " worm " 
 at all, but a moth, which, like all moths and butterflies, 
 is first a caterpillar, hatched from a tiny egg. It feeds 
 on leaves and sheds its skin from time to time as it grows, 
 an operation which is made easier by the secretion of an 
 oily fluid between the new and the old skins. When fully 
 grown the caterpillar commences to spin a cocoon of 
 silk. The thread issues from a spinneret and is something 
 similar to the thread of a spider's web. In the silkworm, 
 however, the spinneret is not situated in the abdomen, 
 but in a nipple-like swelling on the caterpillar's lower 
 lip. As the fine thread issues from this spinneret it 
 hardens on exposure to the air. The spinning of the 
 cocoon takes about four or five days, and the amount 
 of thread spun is about 1,000 feet in length. When the 
 silkworm is kept for profit, this thread is subsequently 
 unwound by mechanical means, and is then spun into 
 silk proper. It is estimated that this little insect furnishes 
 employment to over 100,000 people in Great Britain and 
 America alone, while many fortunes have been made 
 and lost through it. 
 
 IX. 
 
 The eggs of butterflies, moths, and other insects furnish 
 a countless variety of objects for examination. To the 
 naked eye they sometimes appear as greyish spots on 
 
 (2,084) 1 j 
 
138 THE MICROSCOPE. 
 
 the leaves of plants, often occurring in clusters. In the 
 microscope we find them to have a beautiful pearly-white 
 appearance, often delicately coloured, with yellow, green, 
 or red. They are of all manner of shapes and designs 
 (b, Plate XXXII.) . Some are perfectly smooth, others 
 are fluted and ribbed, sculptured with rims and grooves 
 which run over their entire surface. So distinct are these 
 varieties that a microscopist should easily be able to name 
 the butterfly by seeing its egg. Some butterflies have 
 such beautiful eggs that they are even of more beautiful 
 design than the eggs of birds. 
 
 Butterflies' eggs are not surrounded by a shell of car- 
 bonate of lime, as are those of birds, but consist of a 
 tough, gelatinous substance which resists strong acids. 
 This so effectively protects the tiny germs within against 
 the elements, that the eggs even may be frozen in a block 
 of ice without killing them. They are thus able to with- 
 stand a severe winter and carry over butterfly life to the 
 following spring, the warm days of which hatch out the 
 tiny caterpillars. 
 
 Butterflies' eggs, as well as those of moths, are very 
 minute objects. They vary in size from less than -^ inch 
 to T V inch in diameter. The former would easily drop 
 through a hole made in a piece of paper by a pin. They 
 are generally of two kinds, " upright " and " flat," and 
 may be laid in large batches or singly. They are found in 
 all kinds of places on bark or twigs of trees in the winter, 
 and in grass or on leaves in the summer. As a rule the 
 mother butterfly takes care to lay the eggs on the leaves 
 of the tree on which the young caterpillar likes best to 
 feed, so that when it hatches out it will have plenty of 
 
 
BUTTERFLIES' EGGS. 139 
 
 food ready to hand. Sometimes the tiny caterpillar may 
 be seen inside the egg, which always changes colour 
 and appearance as the time for hatching approaches. 
 A caterpillar may take from five or six days to nine 
 months to hatch out from the egg, according to the 
 particular variety of butterfly or moth to which the 
 insect belongs. Some pass the winter in the egg, but 
 others hatch out in a few days, and in the course of time 
 become butterflies, the whole operation taking place 
 during the same summer in which their mother lived. 
 
 W 
 
 FIG. 42. Eggs of (a) Large White Butterfly. (6) Elephant Hawk Moth. 
 (c) Scalloped Oak Moth. 
 
 The eggs of the Large White Butterfly (Pieris bras- 
 sicce] are as remarkable as any. They are golden yellow, 
 upright, and have well-defined ribs which run longi- 
 tudinally (a, Fig. 42). They may be found in clusters 
 during June, generally in the leaves of cabbages, and 
 other similar plants, upon which the caterpillar feeds. 
 The eggs of the Painted Lady (Pyrameis cardui) are also 
 upright and of a pale green colour. They also have 
 longitudinal ribs, and are formed in June, singly, on 
 thistles and nettles. The eggs of the Elephant Hawk 
 Moth (Chcerocampa elpenor) are flat and oval-shaped 
 
I 4 o THE MICROSCOPE. 
 
 (b, Fig. 42). They are green in colour, smooth, and are 
 not decorated at all. They are laid in July on bedstraw, 
 willow-herb, and similar plants, usually those near some 
 stream or pond. 
 
 The Scalloped Oak Moth (Crocallis elinguaria) lays 
 flat eggs which are oblong and smooth (c, Fig. 42). 
 They are brownish white in colour, with patches of dark- 
 brown, and are usually found in straight rows, side by 
 side, along blackthorn twigs. They are laid in July and 
 August, and will not hatch until the following spring. 
 
 X. 
 
 At one time the house-fly was looked upon by some 
 people as being one of our insect friends, for it acts as a 
 scavenger, eating up refuse. Further investigations more 
 recently have shown that flies are very harmful to us, 
 for they carry disease, and it is because of this that we 
 have been requested by posters and public notices to 
 " kiU that fly." 
 
 The common house-fly (Musca domestica) has one pair 
 of wings, and is therefore classed among the diptera or 
 double-winged insects. Its wings consist of a double 
 membrane, strengthened by nervures like those of the 
 bee. It has also two appendages, the halteres or poisers, 
 and these are sometimes called undeveloped or rudi- 
 mentary wings. They seem to act as balances and enable 
 the fly to walk in difficult circumstances. 
 
 The house-fly's tongue is a common object in the 
 microscope, and the proboscis of the blow-fly is a well- 
 known object for testing the quality and defining the 
 power of lenses (Plate XXXIII.). The house-fly's tongue 
 
PLATE XXXIV 
 
 From a photo-micrograph by] 
 
 A GNAT 
 
 [A. E. Smith 
 
THE HOUSE-FLY. 141 
 
 consists of two parts, the pharynx and the mouth itself. 
 The pharynx is a kind of throat tube which extends 
 beyond the mouth when the fly is feeding, but when not 
 in use it lies in the head. The mouth itself is situated at 
 the end of the pharynx. The proboscis carries numerous 
 hairs of various shapes well seen in that of the blow-fly 
 some of which are thicker than others. Those at the end 
 are tubular, and when the tongue is extended in eating, 
 these hairs fill with air and stiffen, thus protecting the 
 delicate parts. When the insect has finished eating and 
 draws in its tongue, the hairs are emptied of air, and 
 become easily movable, so as not to interfere with the 
 folding of the proboscis in the head. 
 
 The fly eats in a curious manner. Watch a fly after it 
 has " settled " on some sugar. It first impels its pro- 
 boscis, and extending it out of its head, causes the two 
 broad fan-like appendages to appear from the top. 
 These act as files and suckers, and with them a little 
 sugar is filed off. The fly then pours some fluid upon 
 this from its mouth organs. This forms a kind of syrup, 
 which is at once sucked up. The tubes of the proboscis 
 are kept open by a spiral arrangement of hair-like fibre, 
 in a similar manner that the garden hose-pipe is kept 
 from bending, or " kinking," by an internal spiral wire. 
 A fly does not bite or sting, as we sometimes suppose, 
 but grates or files with the little tools at the end of its 
 proboscis. 
 
 The fly has three pairs of legs, and each is divided into 
 five parts. The tarsus, or foot, is fitted with two formid- 
 able claws, also a delicate pad, carrying many tubular 
 hairs, and covered with a sticky fluid. This enables 
 
142 THE MICROSCOPE. 
 
 the foot to adhere to slippery objects, and the fly is 
 thus able to walk up a pane of glass or similar smooth 
 surface. 
 
 The fly has a comparatively large " heart," or dorsal 
 vessel, as it is called, which beats. The blood flows 
 through the fly's body in the reverse way to that of ours, 
 being forced by the contraction of the heart from tail 
 to head. 
 
 When we speak of insects having blood, we do not 
 mean blood similar to that of human beings any more 
 than we mean their dorsal vessel is a true heart. The 
 blood of insects is transparent, nearly colourless, and 
 differs in other respects from our blood. It is kept pure 
 by aeration by trachea, which, as we have already seen, 
 are air-tubes running through the insect's body. 
 
 Flies are to a certain extent of use in the economy of 
 nature, for they consume decaying matter that would not 
 otherwise be removed, and which in hot weather would 
 perhaps harbour disease. Linnaeus, a celebrated natural- 
 ist, said that three flies would consume a dead horse as 
 quickly as a lion. He meant, of course, these flies and 
 their offspring. It has since been said that the saying 
 is probably quite correct, since the young begin to eat 
 as soon as they are hatched, and a female blow-fly will 
 produce 20,000 living larvae. In twenty-four hours each 
 will have increased in weight 200 times, in five days 
 attaining their full size, changing to the pupae, and 
 then to the perfect insect. 
 
 Although flies are, beyond doubt, of some value as 
 scavengers, they are the cause of much trouble in other 
 ways. The house-fly may carry germs of disease upon 
 
PLATE XXXV 
 
 From a photo-micrograph by] 
 
 A FLEA 
 
 [A. E. Smith 
 
THE GNAT. 143 
 
 its feet and proboscis and, by its dirty method of eat- 
 ing already described transfer these to human food. 
 The larvae of the Bott fly, or "horse-fly," often bore 
 into the skin of sheep and cause these animals great 
 irritation and pain, which sometimes results in death. 
 The Tse-tse fly is the carrier of the organisms which 
 cause the dreaded sleeping sickness in Africa and the 
 tropics. 
 
 XL 
 
 The ghat (Plate XXXIV.) has very graceful antenna, 
 and indeed, as we might well expect, it shows very 
 delicate structures when magnified. The male gnat has 
 plumed antenna, which are marked by their lightness 
 and grace. As in the case of the bee, the gnat's antenna 
 consist of many joints, generally about fourteen, and from 
 each of these spring hairs. In the case of the male, 
 these hairs are very numerous and of great length, thus 
 giving the plumed appearance already mentioned. 
 
 Gnat-grubs may be obtained in the summer from almost 
 any water-tub or pond, for they swarm on the surface 
 of the water. These grubs are partly transparent, and 
 through the outer covering may be seen the flat, rounded 
 head, the great swollen thorax, and finally the long, 
 slender, many-jointed body. The head shows a pair 
 of rod-like antenna, two black patches marking the place 
 of the eyes-to-be, and the jaws, covered with rows of 
 strong hairs and ever working with rapid vibrations. 
 The thorax is so transparent that as in the case of 
 Daphnia we may watch the gnat's heart, or dorsal 
 vessel, as we should call it, beating and pulsating with 
 
144 THE MICROSCOPE. 
 
 beautiful regularity. Sometimes we may discern a dark 
 pellet of food descending through the " throat," and this 
 explains the constant vibrations of the jaws, which collect 
 the food from the water in minute particles and form it 
 into a pellet to be passed into the stomach when suffici- 
 ently large. All these may be seen if the grub is young 
 enough, for then the tissues of the outer covering are 
 beautifully transparent and resemble amber. As the 
 insect grows older, however, the tissues become opaque 
 and the fine details cannot be made out. 
 
 To a certain extent the wings of the gnat resemble 
 those of the bee. Two transparent membranes are 
 strengthened by nervures. Both sides are covered with 
 numerous and minute short spine-like hairs, while along 
 the nervures and outer edges of the wings are set long 
 hair-like scales. When one of these scales is examined 
 with a high power it is seen to be a leaf-shaped plate of 
 transparent substance and of curious appearance. 
 
 XII. 
 
 Another common insect rightly classed among the 
 " enemies "is the flea (Plate XXXV.). This was a 
 favourite object for examination and show purposes with 
 early microscopists. The flea does not " bite/' although 
 its attentions are so-called. In its mouth-part is a fine, 
 sharp piercing organ like a lancet. With this it pricks 
 the skin of its victim and sucks out the blood. The 
 irritation is caused by the flea injecting into the wound 
 a drop of poisonous liquid, by which the blood of the 
 victim becomes more fluid and thus is more easily 
 sucked up. 
 
PLATE XXXVI 
 
 From photo-micrographs by] (b) [C. D. Holmes 
 
 <&) SPINNERETS OP THE SPIDER. (b) SPIDER'S CLAW 
 
MITES AND TICKS. 145 
 
 XIII. 
 
 Mites and ticks are not insects, but are really associated 
 with spiders. As they are " fleas " to animals and in- 
 sects, however, we may perhaps say a word or two about 
 them here. In the perfect state they resemble spiders 
 in the number of their legs, eight. Sometimes they are 
 found with only six legs, sometimes with even only four, 
 but when found thus they are in an immature state. 
 Some find their food in plants or decaying matter, but 
 others are parasites. 
 
 The Gramasida, or insect-mites, are perhaps the best 
 known. They may be found on beetles, flies, bees, and 
 other insects. They cling to the bodies of their hosts, 
 and a hand lens will often show their struggles in the 
 downy hairs which cover the bee's body. 
 
 Mites are also found in fresh and salt water, in the 
 latter case on seaweed in rock pools. Fresh-water mites 
 are often partly coloured with red or purple and have 
 an appearance like velvet. At the tip of their feelers, 
 or palpi, they have a tiny hook, and with this they hook 
 themselves to marine creatures. Over twenty species 
 of fresh-water mites have been discovered in ponds in 
 England alone. Mites may also be obtained from hanging 
 hams or flour which has been kept in a bin for any length 
 of time. The cheese mite (Acarus domesticus) is well 
 known, and examples may be obtained from cheese 
 which has been kept a long time. 
 
 Ticks are somewhat larger than mites, are oval in 
 shape, and have a sucking mouth. Some are blind, but 
 others have eyes. They live on herbage, as a rule. 
 
 (2,084) 19 * 
 
146 THE MICROSCOPE. 
 
 The female sometimes causes a great deal of trouble 
 by piercing the skin of some warm-blooded animal 
 and sucking its blood. Much pain and suffering is 
 thus caused to cattle. Sometimes when walking in the 
 fields you may have seen a starling pecking away in 
 a curious way at the fleece of some sheep. These birds 
 are really feeding upon the sheep's ticks entangled in 
 the wool. The sheep goes on eating its grass while the 
 operation is in progress, well pleased no doubt at the 
 efforts of these birds to free it from the painful pest. 
 The sheep tick, however, is an insect, and not really a 
 tick. It has only six legs, and is placed among the 
 lower flies diptera although it has no wings. It is 
 thought that the sheep tick is a descendant of some higher 
 type of insect, and that probably it has become a parasite 
 owing to its remote ancestors acquiring the habit of 
 feeding themselves at the expense of other animals. 
 Becoming too lazy to seek its food by hard work, it 
 obtained it easily and without much effort in the manner 
 already indicated. Now, Nature has decreed that 
 faculties which remain inactive and are not wanted 
 shall be done away with. Thus, seeing that the sheep 
 tick did not use its wings, they have gradually disappeared, 
 with the result that the sheep tick of to-day has none. 
 Not only is it absolutely dependent upon its host, there- 
 fore, but also it cannot fly away from the starling and 
 the crow, which pick it out of the sheep's tangled wool. 
 
PLATE XXXVII 
 
 From a photograph by] 
 
 1 
 
 [W. Coles-Finch 
 
 YOUNG SPIDERS HATCHING OUT 
 
CHAPTER XIII. 
 MINIATURE ENGINEERS: SPIDERS. 
 
 I. 
 
 THE spider, with its wonderful power of designing 
 and spinning webs, may indeed be called a minia- 
 ture engineer. Never was a gulf bridged more effectively 
 with iron and steel than is the space between branches 
 or leaves by the web of the spider. There is, however, 
 an important distinction between the two bridges, for 
 whereas that of human beings is used for traffic, the web 
 of the spider is a trap or snare by which the little blood- 
 sucker obtains its food. 
 
 The name " spider " is derived from the old English 
 word spinder, " a spinner." You have no doubt heard 
 some people speak of spiders as insects, but this is not 
 scientifically correct. They belong to a sub-class of 
 Anthropoda, called Arachnidce, and are related to scor- 
 pions and mites. They come between crustaceans like 
 the lobsters and true insects in their classification. 
 It is useful to remember that the highest forms of crus- 
 taceans have ten feet, Arachnidce eight, and insects six. 
 Also that Arachnidce have several simple eyes, are as a 
 
 147 
 
148 THE MICROSCOPE. 
 
 rule wingless, have no antenna, and breathe by tracheal 
 tubes and sacs. They are mostly carnivorous, or flesh- 
 eating, and because they live on insects they may be 
 regarded as friends by the gardener, for they destroy 
 many pests which might otherwise damage fruit and 
 flowers. They also help to keep down what would 
 otherwise assuredly be a plague of flies, for the whole 
 tribe of spiders are fly-butchers by profession. Just as 
 our butchers have their slaughter-houses, knives, pole- 
 axes, and hooks, so these little slaughterers have their 
 nets, traps, and caves, their fangs, hooks, and poison 
 bags. " No one/' wrote Professor Rymer Jones, " who 
 looks at the armament of a spider's jaws can mistake the 
 intention with which this terrible apparatus was planned. 
 ' Murder ' is engraved on every piece that enters into 
 his composition." 
 
 There are about 2,500 known species of spiders, of 
 which some 550 are to be found in the United Kingdom. 
 Many of them make most interesting pets and grow quite 
 tame. No doubt you have read of the poor prisoner 
 in the Bastille who whiled away the long hours of his 
 captivity by taming a spider which occupied his dungeon 
 with him. 
 
 II. 
 
 The spider's body is made up of three parts, the head, 
 thorax, and abdomen, but the head and thorax are almost 
 merged into one. As in the case of insects the legs are 
 attached to the thorax, and are so placed as to allow 
 great freedom of motion. The abdomen is of large size, 
 especially in female spiders, and is often beautifully 
 coloured and decorated with peculiar designs. Especially 
 
PLATE XXXVIII 
 
 From a photograph by] [W. Coles-Finch 
 
 GARDEN SPIDER REPAIRING WEB 
 
THE SPIDER'S WEB. 149 
 
 is this so in the case of the upper surface, where the 
 markings are like mosaic, and often take the form of a 
 cross. The legs are covered with stout bristles and are 
 provided with claws, of which we shall speak later. 
 
 The majority of spiders have very small mouths, and 
 can therefore consume only liquid food, which they suck 
 from their prey. In most cases spiders capture this prey 
 by spinning webs, and it is because they spin these webs 
 that the class to which they belong is called Arachnidce. 
 Arachne was a Lydian maiden, so skilful in needlework 
 that she challenged Minerva, the goddess of the art, 
 to a trial of skill. Although Arachne's hand-work was 
 exquisite, Minerva's was even more beautiful. In despair 
 at her work being surpassed Arachne hanged herself, 
 but was changed into a spider by the goddess. When 
 we see the beautiful work of the spider, it is interesting 
 to recall this old Greek legend. 
 
 III. 
 
 It is the spinning of these webs and the apparatus for 
 this work which is the most interesting part of the 
 spider's anatomy to the microscopist. The spinning 
 organs of these spiders which construct circular webs 
 are the most complicated. 
 
 The gossamer threads of which the webs are composed 
 are among the finest lines in creation. They issue from 
 the spinnerets, which are small teat-like swellings in the 
 under side of the abdomen (a, Plate XXXVL). Their 
 position is well seen in Plate XXXVIII., in which is 
 depicted a female garden spider repairing her damaged 
 web, at the same time holding a fly in her mandibles. 
 
150 THE MICROSCOPE. 
 
 These spinnerets vary in number in different spiders, some 
 having four, others six. Sometimes, but not often, there 
 may be as few as two or as many as eight. In those 
 spiders which have six spinnerets we have to look care- 
 fully for the extra two, as sometimes it would seem as 
 though there are only four. The spider can move the 
 spinnerets as it wishes, raising or lowering them, and 
 using one, many, or all of them, as it requires. Each 
 spinneret consists of a large number of silk tubes, which 
 in the common garden spider amount to 600. There 
 are also different kinds of spinning glands, and in this 
 same spider these are five in number. The silk of each 
 of these glands differs in nature, and is skilfully employed 
 as required by the spider. For instance, some of the 
 larger tubes in the teats give out a more sticky fluid than 
 the others. They are all combined to form one thread, 
 as various strands of hemp are combined to form a rope, 
 except that the spider's strands are not twisted in the 
 way that a rope is. 
 
 Nearly all spiders encase their eggs in a cocoon of 
 silken thread, and store them in a sheltered place. Here 
 they pass through the cold days of winter and await 
 the coming of spring and warm weather, which will 
 hatch out the young spiders. In the case of the Wolf 
 Spider, the female always carries the cocoon containing 
 the eggs with her, and vigorously resists any attempt 
 to separate her from it. 
 
 IV. 
 
 The spider does not undergo metamorphosis, or " change 
 of form," like many insects, such as butterflies and bees, 
 
PLATE XXXIX 
 
 From a photograph by] [W. Coles-Finch 
 
 WEB OF GARDEN SPIDER COVERED WITH DEW 
 
THE GARDEN SPIDER. 151 
 
 which are first eggs and then become grubs, before they 
 finally assume the perfect state of the fully developed 
 insect. Spiders resemble the cockroach and grasshopper, 
 assuming the adult form as soon as hatched, and thus 
 developing direct from an egg to a spider. The female 
 spider lays her eggs in the early autumn, producing 
 perhaps 200 or 300 in quick succession. She rolls them 
 into a kind of ball with her legs, encircles them with a 
 thick covering of web, and deposits them in some shel- 
 tered position. You may often find one of these nests 
 in some garden wall or fence, looking like a large chrysalis 
 of a pale yellow colour. Sometimes it is covered with 
 dirt and leaves which match the surroundings. These 
 the spider has woven into the outer layers for protection, 
 for the cocoon is a delicate morsel for hungry birds at a 
 time of the year when food is scarce. When the spring 
 comes, the eggs hatch and myriads of tiny spiders are 
 to be seen in some cases no larger than a pin's head 
 all busily occupied in exercising their legs as well as their 
 silken surroundings will allow (Plate XXXVII.). These 
 soon commence housekeeping on their own account, as 
 the numerous webs on surrounding plants and bushes 
 testify. 
 
 V. 
 
 One of the best-known spiders is the Garden Spider, 
 already mentioned (Plate XXXVIII.) . Its scientific 
 name is Epeira diademata, and it is the largest variety 
 found in this country. It may easily be recognized by 
 the white and yellow spots with which its body is covered, 
 and the dark bands and spines on its long legs. Its body 
 
152 THE MICROSCOPE. 
 
 is usually some shade of brown or grey, although some- 
 times it may be vivid green, or even, chameleon-like, 
 change colour with its surroundings. 
 
 It has four pair of eyes arranged in two rows ; the 
 male is much smaller than the female and is often in 
 danger of his life, especially after paying his attentions 
 to the female, for she frequently makes a meal of him ! 
 If he is wise the male spider will leave a line of web 
 hanging near by when he goes a-courting. He can then 
 rapidly escape from the side of the female if she attempts 
 to eat him, and as the hanging line is not strong enough 
 to bear the weight of the female the male will escape if 
 he is quick enough. Sometimes both male and female 
 will li ve together in . quite a friendly manner. One 
 particular pair I know of shared the same geranium leaf 
 day after day, huddling close together during the nights 
 in the same web. 
 
 The Garden Spider spins the beautiful geometrical web 
 which looks so exquisite in the early morning when covered 
 with thousands of dewdrops (Plate XXXIX.) . When spin- 
 ning its web, the spider first lays the foundations, or the 
 
 FIG. 43. Threads of spider's web. (a) Trapping lines. 
 (6) Web lines. 
 
 " spokes " of the wheel-design. These consist of a strong 
 and simple double thread, which hardens rapidly by 
 exposure to the air (b, Fig. 43). Then, lying across this 
 scaffolding, are placed the circular threads like the main- 
 
From a photograph by] [J. Holmes 
 
 TRANSPARENT NEST OP WATER SPIDER 
 
THE SPIDER'S LEGS. 153 
 
 spring of a watch. These threads are covered with a 
 sticky fluid from the larger tubes, and in the microscope 
 look like a thread strung with minute beads (a, Fig. 43). 
 It has been estimated that as many as 120,000 of these 
 globules are contained in a large web. 
 
 VI. 
 
 Spiders spin their webs as traps in which to catch 
 flies and other insects which they require for food. Some- 
 times a web may be completely spun in forty-five minutes, 
 or it may occupy as long as four or five hours. When it 
 is finished, Epeira will wait in the centre of the web, 
 or concealed close by in a den of leaves. If the latter is 
 the case she will generally lay a trap line from the hub, 
 or centre of the web, to her den, by means of which she 
 can instantly tell when a fly has touched the snare. 
 Spiders are largely dependent upon their sense of touch 
 for information as to what takes place in their web. 
 
 A spider has eight legs, each curiously constructed 
 and terminating in a strong, horny claw, having the 
 appearance of a small comb (b, Plate XXXVI.) . The 
 teeth of this comb are set close together and enable the 
 spider to obtain a firm foothold in its web, and thus she 
 is able to walk easily on a single strand. Her feet not 
 only regulate the issue of the silken threads and separate 
 them, but also they are sensitive to an exquisite degree. 
 It is by resting them on the trap line, already mentioned, 
 that the spider is able to feel when a fly has entered 
 her web. 
 
 It is believed that a spider resorts to a practice known 
 as " trolling the fly." She attaches a strand to her 
 
 '2,084) 20 
 
I 5 4 THE MICROSCOPE, 
 
 victim, already helplessly entangled in the meshes of her 
 web, and turns the fly round and round like a joint on 
 a spit. By these means the fly is soon completely en- 
 tangled in the silken strand and is left trussed up, hanging 
 like a ham from the ceiling of a farmhouse. If a wasp or 
 heavy insect blunders into the web, the spider is out at 
 once, drawing long threads around her struggling prey 
 from a safe distance. Once the prey is bound, it is soon 
 inflicted with a bite from the spider's poison fangs, 
 and its doom is sealed. 
 
 The water spider (Argyroneta aquatica) is an extremely 
 interesting pet, which can be kept in an aquarium. 
 It builds a dome-shaped nest, something like a thimble, 
 below the surface of the water (Plate XL.). This is a 
 curious habit, for the spider is only fitted out for air- 
 breathing. She overcomes the difficulty, however, by 
 carrying down to the nest each time she dives a bubble 
 of air which becomes entangled in the hairs of her body. 
 To see her carrying down the silver bubbles, and filling 
 her nest with air, converting it into a tiny diving bell, 
 is indeed a fascinating sight. 
 
 Space forbids my describing any more of the wonders 
 of spiderland, but if you wish to do so, you can learn 
 for yourself of the wonderful instinct of the mother spider 
 for her young, of the industry of spiders, of the ballooning 
 spiders, of the wonderful cave-dwellers, and of the cunning 
 of the trap-door spider. 
 
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 STORIES FROM SHAKESPEARE. 
 
 HANS ANDERSEN. 
 
 THE PILGRIM'S PROGRESS. 
 
 UNDINE. 
 
 NURSERY TALES. 
 
 STORIES OF ROBIN HOOD. 
 
 UNCLE TOM'S CABIN. 
 
 THE WATER BABIES. 
 
 OLD TESTAMENT STORIES. 
 
 STORIES FROM DON QUIXOTE. 
 
 STORIES OF ROLAND.