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® 


THE MICROSCOPE 


PRONTISPIECR, 


1 





THE 


MICROSCOPE 


ITS REVELATIONS 


BY THE LATE 


WILLIAM B. CARPENTER, C.B., M.D., LL.D., F.R.S. 


SEVENTH EDITION 


IN WHICH THE FIRST SEVEN CHAPTERS HAVE BEEN ENTIRELY REWRITTEN 
AND THE TEXT THROUGHOUT RECONSTRUCTED, ENLARGED, AND REVISED 
BY THE REY, 


W. H. DALLINGER, LL.D., F.R.S., &c. 


WITH TWENTY-ONE PLATES AND EIGHT HUNDRED Woub ENGRAVINGS 





LONDON 
J. & A. CHURCHILE 
1 NEW BURLINGTON STREET 
1891 
B 


AML rights reserved 


Crzsa 
133 


PREFACE 


Tax use of the Microscope, both as an instrument of scientific research 
and as a means of affording pleasure and recreative instruction, has 
become so widespread, and the instrument is now so frequently found 
in an expensive form capable of yielding in skilled hands good 
optical results, that it is eminently desirable that a treatise should 
be within the reach of the student and the tiro alike, which would 
provide both with the elements of the theory and principles involved 
in the construction of the instrument itself, the nature of its latest 
appliances, and the proper conditions on which they can be em- 
ployed with the best results. Beyond this it should provide an 
outline of the latest and best modes of preparing, examining, and 
mounting objects, and glance, with this purpose in view, at what is 
easily accessible for the requirements of the amateur in the entire 
organic and inorganic kingdoms. 

This need has been for many years met by this book, and 
its six preceding editions have been an extremely gratifying evidence 
of the industry and erudition of its Author. From the beginning 
it opened the right path, and afforded excellent aid to the earnest: 
amateur and the careful student. 

But the Microscope in its very highest form has become—so far 
at least as objectives of the most perfect construction and greatest 
useful magnifying power are concerned--so common that a much 
inure accurate account of the theoretical basis of the instrument 
itself and of the optical apparatus employed with it to obtain the 
best results with ‘1 powers’ is a want very widely felt. 

The advances in the mathematical opties involved in the con- 
struction of the most perfect form of the present Microscope have 
been very rapid during the last twenty years ; and the progress in 
the principles of practical construction and the application of theory 
have, even since the last edition of this book was published, been so 
marked as to produce « revolution in the instrument itself and in its 








REAM 





vi PREFACE 


application. The new dispensation was dimly indicated in the last 
edition ; but it has effected so radical a change in all that apper- 
tains to Microscopy that a thorough revision of the treatment of 
this treatise was required. The great principles involved in the 
use of the new objectives and the interpretation of the images pre- 
sented by their means, are distinct and unique ; and unless these be 
clearly understood the intelligent use of the finest optical appliances 
now produced by mathematical and practical optics cannot be 
brought about. They have not rendered the use of the instrument 
more difticult—they have rather simplified its employment, provided 
the operator understands the general nature and conditions on 
which his Microscope should he used. If the modern Microscope be, 
asa mechanical instrument with its accompanying optical apparatus, 
as good as it can be, a critical image—a picture of the object having 
the most delicately beautiful character—is attainable with ‘low 
powers’ and ‘high powers’ alike. Microscopists are no longer 
divisible into those who work with ‘high powers’ and those who 
work with ‘low powers.’ No one can work properly with either 
if he does not understand the theory of their construction and the 
principles upon which to interpret the results of their employment. 
If he is familiar with these the employment of any range of magni- 
fying power is simply a question of care, experiment, and practice ; 
the principles applicable to the one are involved in the other. Thus; 
for example, a proper understanding of the nature and mode of 
optical action of a ‘sub-stage condenser’ is as essential for the very 
finest results in the use of a I-inch object-glass as in the use of @ 
2 mm. with N.A. 1-40 or the 25 mm. with N.A. 1:60, while it 
gives advantages not otherwise realisable if the right class of con- 
denser_used_in_the right way be sluyed with the older Jyth inch 





PREFACE vit 


must be essentially a cyclopedic work. ‘This was far more possible 
toone man when Dr. Carpenter began his work than it was even 
when he issued his last edition. But it is practically impossible 
wow. It is with Microscopy as with every department of scientific 
vork—we must depend upon the specialist for accurate knowledge. 

In the following pages I have been most generously aided. In 
wo department, not even that in which for twenty years I have 
been specially at work, have I acted without the cordial interest, 
sggestion, and enlightenment afforded by kindred or similar workers. 
In every section experts have given me their unstinted help. 
To preserve the character of the book, however, and give it homo- 
geneity, it was essential that all should pass through one mind and 
be so presented. My work for many years has familiarised me, 
more or less, with every department of Mictoscopy, and with the 
great majority of branches to which it is applied. I have therefore 
given a common form, for which I take the sole responsibility, 
to the entire treatise. The subject might have been carried over 
ten such volumes as this; but we were of necessity limited as 
to space, and the specific aim has been to give such a condensed 
view of the whole range of subjects as would make this treatise 
at once a practical and a suggestive one. 

The first five chapters of the last edition are represented in this 
edition by seven chapters ; the whole matter of these seven chapters 
has heen re-written, and two of them are on subjects not treated in 
any former edition. These seven chapters represent the experience 
of a lifetime, contirmed and aided by the advice and practical help 
of some of the most experienced men in the world, and they may be 
real by anyone fatniliar with the use of algebraic symbols and the 
practice of the rule of three. They are not in any sense abstruse, 
and they are everywhere practical. 

In the second chapter, on ‘The Principles and Theory of Vision 
with the Coinpound Microscope, so much has been done during the 
past twenty years by Dr. Anne, of Jena, that my first desire was to 
induce him to summarise, for this treatise, the results of his twenty 
years of unremitting and marvellously productive labour. But the 
state of his health and his many obligations forbade this ; and at 
length it became apparent that if this most desirable end were to 
be secured, I must re-study with this object all the monographs of 
this author, I summarised them, not without anxiety ; but that was 
speedily removed, for Dr. Ane, with great generosity, consented to 
examine my results, and has been good enough to write that he has 
‘read [my] clear expositions with the greatest interest ; and, after 
words which show his cordial friendliness, he says: ‘I tind the whole 
... much more adequate to the purposes of the book than I should 














viii PREFACE 





have been able to write it. . I feel the greatest satisfaction in 
seeing my views represented in the book so extensively and inten- 
sively.’ 

These words are more than generous ; but I quote them here 
in order that the reader may be assured of the accuracy and 
efficiency of the account given in the following pages of the invalu- 
able demonstrations, theories, and explanations presented by Dr. 
Anne on the optical principles and practice upon which the recent 
improvement in the construction of microscopical lens systems has 
80 much depended. 

It will not be supposed that I implicitly coincide with every 
detail. Dr. Ape is too sincere a lover of independent judgment 
to even desire this. But it was important that his views as such 
should be found in an‘accessible English form ; in that form I have 
endeavoured to present them ; and in the main there can be no 
doubt whatever that these teachings are absolutely incident with 
fact and experience. In details, as may appear here and there in 
¢ pages, especially where it becomes a question of practice, I may 
differ ns to method, and even interpretation, from this distinguished 
master in Mathematical Optics. But our differences in no way affect 
the great principles he has enunciated or the comprehensive theory 
of microscopical vision he has with such keen insight laid down. 

In preparing the remainder of the seven new chapters of this 
ook T have sought and, without hesitancy, obtained advice and 
the advantage of the support of my own judgment and experience 
from many competent men of science, who have shown a sincere 
interest in my work and have aided me in my endeavours, But, 
first on the list, I must place my friend Mr. E. M. Netson, Our 
lines of experience with the Microscope have run parallel for many 














x PREFACE 


and pleasure will be greater in proportion as a knowledge of the- 
general principles on which the instrument is constructed are known, 
and as the principles of visual interpretation are understood. The- 
interests of these have been specially considered in the following 
pages ; but such an employment of the Microscope, if intelligently 
pursued, often leads to more or less of steady endeavour on the part 
of amateurs to understand the instrument and use it to a purpose 
in some special work, however modest. This is the reason of the 
great increase of ‘Clubs’ and Societies of various kinds, not only in 
London, and in the provinces, but throughout America ; and these 
are doing most valuable work. Their value consists not merely in the 
constant accumulation of new details concerning minute vegetable 
and animal life, and the minute details of larger forms, but in the 
constant improvement of the quality of the entire Microscope on its 
optical and mechanical sides. It is largely to Amateur Microscopy 
that the desire and motire for the greatimprovements in object-glasses 
and eye-pieces for the last twenty years are due. The men who have 
compared the qualities of respective lenses, and have had specific ideas 
as to how these could become possessed of still higher qualities, have 
been comparatively rarely those who have employed the Microscope 
for professional and educational purposes. They have the rather 
simply wed -employed in the execution of their professional work 
—the best with which the practical optician could supply them. 
It has been by amateur microscopists that the opticians have been 
incited to the production of new and improved objectives. But it 
is the men who work in our biological and medical schools that 
ultimately reap the immense advantage—not only of greatly im- 
proved, but in the end of greatly cheupened, object-glasses. It is 
on this account to the advantage of all that the amateur micro- 
scopist should have within his reach a handbook dealing with the 
principles of his instrument and his subject. 


EXPLANATION OF PLATES 


FRONTISPIECE 


Fig. 1. 6 diameters. Horizontal and transverse section of an orbitolite. 

Fig. 2. An imperfect or uncritical image of the minute hairs on the lining 
membrane of the extremity of the proboscis of the blow-fiy x 510 diams,, taken 
with a Zeiss apochromatic }-inch objective of ‘95 N.A. x 3 projection eye-piece ; 
but it was illuminated by a cone of small angle, viz. of 0-1 N.A., and illustrates 
the unadvisability of small cones for illumination. 

The first obvious feature in the picture is the doubling of the hairs which 
are out of focus; but the important difference lies in the bright line with a 
dark edge round the bairs which are precisely in focus. This is a diffraction 
effect which is always present round the oatlines of every object illuminated 
by a cone of insufficient angle. Experiment shows that this diffraction line 
always ceases to be visible when the aperture of the illuminating cone is equal 
to about two-thirds the aperture of the objective used; but it will become 
again distinctly apparent when the aperture of the cone is reduced lese than 
talf that of the objective. 

Fig. 3, x 510diams. A correct or critical image of the minute hairs on the 
lining membrane of the extremity of the blow-fly’s proboscis. In this picture 
the focus has been adjusted for the long central hair. It will be observed that 
this hair is very fin \1 spinous ; it has not the ring socket which is common 
to many hairs on insects, but grows from a very delicate membrane, which in 
the balsam mount is transparent. This photograph was taken with a Zeiss 
apechromatic } of ‘95 N.A. x3 projection cye-piece. ‘The illumination was 
that of a large solid axial cone of -65 N.A. from an achromatic condenser, the 
swurce of light being focussed on the object. 

Fig. 4. Section of cerebellum of a lamb, x 77 diams., by apochromatic l-inch 
aNA preparation was courteously supplied to the present Editor by Dr. 
Hijll, whose imbedding and staining processes for these tissues it beautifully 
illustrates. 

Fig. 5. Amphipleura pellucida x 1860 diams., by apochromatic 4 1-4 N.A. 
itluminated by a very cblique pencil in one azimuth along the valve. 

Fig. 6. A hair of Polysenus lagurus, a well-known and excellent test 
ct for medium powers x 490 diams. by apochromatic 4-95 N.A. 

Fig. 7, A small vessel in the bladder of a frog, prepared with nitrate of 
silver stain, showing endothelium-cells, x 40 diams., by Zeiss A. This 
ubject bas been photographed for the purpose of exposing the fallacy which 
unilerlies the generally accepted statement that ‘low-angled’ glasses are the 
most suitable for histological purposes. ‘The supposition that it is so has 
been founded on the fact that the penetration of a lens varies inversely as its 
aperture; therefore, it is said, a ‘low-angled’ glass is to be preferred to a 
wile-angled one, because ‘depth of focus, which is supposed to enable one 
the end in view. 

Onearefully éxamining this figure it will be noticed that it is almost 























obye 
























xii EXPLANATION OF PLATES 


impossible to trace the outline of any particular endothelium-cell because i# © 
image is confosed with that of the lower side of the pipe. In a monoct 
microscopical image a perspective view does not exist ; it is better, therefore, #2 
use a wide-angled lens, and so obtain a clear view of a thin plane at one tima> 
and educate the mind to appreciate solidity by means of focal adjustmen#® 
It will be admitted that unless one approaches fig. 7 with a preconceived ides 
of what an endothelium-cell is like, the knowledge gained of it will be 


8 represents the same structure, x 188 diama., by an apochromatic= 
“65 N.A. Here only the upper surface of the pipe is seen, so that the out- 

line of the endothelium-cells can be clearly traced. The circular elastic tissue 

is also displayed. ‘There is, moreover, an increased sharpness over the whole 

picture, due to the greater aperture of the objective. 





PLATE I 


1, The inside of a valve of Pleurosigma angulatum, showing a 
* postage stamp ' fracture, x 1750 diams., with an apochromatic 7 1-4 N.A. by 
Mr. T. F, Smith, and illustrating his view of the rature of the Pleurosigma 
valve. 

Fig. 2. The outside of a valve of Pleurosigma angulatum, showing a dif- 
ferent form of structure, x 1750 diams., with an apochromatic yy 1-4 N.A, by 
Mr. F. Smith. These two photo-micrographs demonstrate the existence of at 
least two layers in the angulatum. 

ig. 3. Coscinodiscus asteromphalus, x 110 diams., with an apochromatic 
J-inch -3 N.A. 

Fig. 4. A portion of the preceding, x 2000 diams. to show the lacework 
inside the areolations. This Iacework is believed to be a perforated stracture, 
ax a fracture passes through the markings. In the central areolation there 
are forty-six smaller perforations surrounded by a crown of fifteen larger ones.” 
Photographed with an apochromatic 4 1-4 N.A. 

ig. 5. Aulacodiscus Kittonii, x 270, by an apochromatic I-inch 8 N.A. 

Fig. 6. A small Portion. in the centre of an Aulacodiscus Sturtii, x 2000, 
by an apochromatic 4 1-4.N.A. Broadly speaking, the difference between the 
Coscinodisci and the Aulacodisci lies in the fact that in the former the 
secondary structure is inside the primary, while in the latter it is exterior to it. 
This definition, however, is not strictly accurate, as it is believed that the fine 
perforated structure covers the entire valve, it being only optically hidden by 
the primary structure. 

The whole of these demonstrations were photographed for the present 
Editor by his friend E. M. Nelson, Esq., and have been reproduced from the 
negatives by a process of photo-printing. 





EXPLANATION OF PLATES xiii 


PLATE V 


METHOD OF USING DIRECT TRANSMITTED LIGHT WITHOUT THE 
EMPLOYMENT OF THE MIRROR 


Puatss II. to V, are engraved from photographs, taken at the request of 
the Editor by Mr. E. Bf. Nelson, from the arranged instruments. 


PLATE VI 
SEXUAL GENERATION OF VOLVOX GLOBATOB. (After Cohn) 


Fig. 1. Sphere of Tolror globator at the epoch of sexual generation : a, 
-cell containing cluster of antherozoids; a*, sperm-cell showing side- 
tlew of discoldal cluster of antherozolds; a’, sperm-cell whose cluster has 
broken up into its component antherozoids; @', sperm-cell partly emptied by 
the escape of its antherozoids; 58, flask-shaped germ-cells showing great 
increase in size without subdivision ; B%, 6%, germ-cells with large vacuoles in 
their interior; #4, germ-cell whose shape has changed to the globular. 
Fig. 2. Sexual cell, a, distinguishable from sterile cells, 8, by its larger 
size. 
Fig. 8. Germ-cell, with antheroids swarming over its endochrome. 
4, Fertilised germ-cell, or odsphere, with dense envelope. 
He 5. Speram-cell, with its contained cluster of antherozoids, more 
enlarged. 
Figs. 6, 7. Liberated antherozoids, with their flagella. 








PLATE VIL 
OSCILLARIACE® AND SCYTONEMACEE, 


Fig. 1. Lyngbya estuarii, Lieb. x 160. 
Fig. 2. Spirulina Jenneri, Ktz. x 400. 
Fig. 3. Tolypothriz cirrhosa, Carm. 400. 
Fig. 4. Oscillaria insignis, Thww. x 400. 
Fig. 5. O. Frolichii, Ktz, x 400. 

Fig. 6. 0. tenerrima, Ktz. x 400. 

‘These figures are after Cooke. 





PLATE VIII 


DESMIDIACE#, KIVULARIAUEA:, AND SCL\TONEMACES 


. 1, Zygosperm of Miorasterias denticulata, Bréb. (After Ralfs.) 
. Cosmarinm Brebissonii, Men. (After Cooke.) 
. Buastrum pectinatum, Bréb. (After Ralfs.) 
4. Zygosperm of Stavrastrum hirutum, Bréb. (After Ralfs.) 
5. S. gracile, Ralfs. (After Cooke.) 
. Xanthidium aculeatum, Ehrb. (After Ralfe. 
7. Rirularia dura, Ktz, (After Cooke.) 
8. R. dura, Ktz. 400, (After Cooke.) 
. Scytonema natans, Bréb. x 400. (Atter Cooke.) 
0, Staurastrum hirsutum, Bréb. (After Cooke.) 





xiv EXPLANATION OF PLATES 


PLATE IX 
IMIDLACE 





. Miorasterias cruz-melitensis, Bhrb. (After Cooke.) 
. Closterinm sctaceum, Ehrb. | (After Cooke.) 
; Deamidium Swartzii, Ag. (After Cooke.) 
| Penium digitus, Ehrb. (After Cooke.) 
5. P. digitus, Ehrb. (transverse view). 
. Spiretenia condensata, Bréb. (After Cooke.) 
, Docidium baculum, Bréb. (After Cooke.) 
. Gonatozygon Brebissanii, De Bary, conjugating. (After Cooke.) 











PLATE X 
PLEUROSIGMA ANGULATUM 


This is a direct photo-micrograph, taken by Dr. R. Zeiss, as magnified 4900 
diameters, We direct attention specially to it as giving evidence of the pre- 








sence (however originated) of the intercostal markings, which may be seen 
with considerable clearness on the right-hand side of the midrib and in the 
iniddle of the valve. 


PLATE XI 


This plate has a twofold purpose. It is designed, first, to justify the 
opinions held by Dr. Henry van Heurck upon the structure of the valves of 
diatoms, and also to show how the usual microscopical tests present them- 

when examined with the new objective with N.A. 1-60, lately constracted 

» Firm of Zeiss. This objective is believed by Dr. van Heurck to realise 
what he considers the highest results of photographie optics, which in bis 
judgment could only be surpassed by finding a new immersion liquid of still 
higher refractive index presenting ali the necessary qualities, and which at the 
xime time would not affect the very delicate flint of which it is necessary to 
make the frontlens of thisobjective. This medinm he hopes may be some day 
realised. Unfortunately, up to this time, no indication permits us to foresee the 
discovery of the liquid desired. 
The following is the way in which Dr. Henry van Heurck summarises his 
ideas upon the structure of the valve 

1. The valve of diatoms’ is formed by two membranes or thin plates and 











EXPLANATION OF PLATES xv 


Such, in brief, is the view held by Dr. van Heurck as an interpretation of 
ar present knowledge of the structure of the valve of the diatoms. We give 
tor a description of the objects represented on the plate. 

Fen 1, 2,5. Amphiploure pellucida, Kits, 1 and 2, valve resolved into 
parls, Fig. 2 x Fig. 1 x 3000 diams. Fig. 3. Valve resolved 
Irate at Shout 2900 dias, 


Fig. 4. Amphipleura Lindheimeri, Gr., x 2500 diams. 

Fig. 5. Plewrevigma angulatum, in hexagons, x (about) 10,000 diams. 

Fig. 6. Idem x 2000 diams,, illusory pearls which are formed by the angles 
the hexagonal cells when the focussing is not perfect. 

Fig. 7. The nineteenth band of Nobert’s test plate. This photo-micro- 

has been made exceptionally with the apochromatic y, of 1-4 N.A. 

The lines being traced upon a cover in crown-glass, the objective of N.A. 1-6 
cannot be used here. 

Fig. 8. Surirella gemma, Ehrb. x (about) 1000 diams. 

_ Fig. 9. Fan Heurokia crassinervis, Bréb. (Frastulia saxonica, Rabh) x 2000 


All the photo-micrographs (except fig. 7) have been done with the new 7- 
inch N.A. 1-60 of MM. Zeiss. 

These micro-photographs have been produced by sunlight in a monochro- 
atic form, the special compensating eye-piece 12, and the Abbe condenser of 

Covers and slides in fiint of 1-72; diatoms in a medium 2-4. 

We are bound, however, to note that the condenser used is not corrected in 
uy way; ite aberrations are enormous. Although the highest admiration must 

be expressed for the skill exercised by Dr. van Heurck in these remarkable 
photo-micrographs, and the highest esteem for his courtesy to the present Editor 
in supplying them, it must not be forgotten that Dr. van Heurck was obliged 
toemploy an imperfect condenser—a condenser absolutely uiicorrected—and. 

rh we can testify to the high quality and fine corrections of at least one 

of the lenses of N.A. 1-6, we are convinced that much of its real perfection 
in image-forming is destroyed by uncorrected sub-stage illumination. Upon. 
the corrections and large aplanatic area presented by the condenser and its 
aefal and efficient employment depends entirely the nature of the image 
prevented by the finest objective ever constructed ; and as the perfection of the 
objective, with a high amplification and a great aperture, is more nearly 
approached, the more dependent are we upon perfect corrections in the con- 
denser to bring out the perfect image-forming power of the objective. No 
image formed by such an objective as that possessing N.A. 1-60 can he consi- 
‘ered reliable until a condenser corrected for all aberrations like the objective 
itself is produced ; and so convinced are we of the possible value of this objec- 
tive that we trust its distinguished devisor and maker may be soon induced to 
Proluce the condenser referred to. 

f, then, by the aid of the chemist we can discover media which will be 
tly high refractive index, and still tolerant of or non-injurious to 
organic tissues immersed in it, a new line of investigation may be open to 
histology and pathology.—W. H. D. 














PLATE XII 
ARACHNOIDISCUS JAPONICUS. (After R. Beck) 


The specimens attached to the surface of a sea-weed are represented as 
en onder a }th objective, with Lieberkiihn illumination: A, internal 
surface: B, external surface ; C, front view, showing incipient subdivision, 





PLATE XIII 


COMPLETE LIFE-HISTORIES OF TWO SAPROPHYTES 
(Drawn from nature by Dr. Dallinger) 


xvi EXPLANATION OF PLATES 


PLATE XIV 


The various stages of the development of the nucleus in two saprophytic 
organisms, as studied with recent homogeneous and apochromatic objectives, 
both in the several stages of fission and genetic fusion, indicating saryoki- 

and proving, as established in detail by the text, that all the steps in 
the cyclic changes of these unicellular forms are initiated in the nucleus before 
being participated in by the whole body of the organism. (Drawn from nature 
by Dr. Dallinger.) 





PLATE XV 


ROTIFERA 


. Floscularia campanwlata, 
. Stephanoceros Kichhornii. 
Melicerta ringens. 
. Pedalion mirum (side view). 
. P. mirum (dorsal view, showing muscles). 
Fig. 6. Copeus cerherus (side view). 
Fig. 7. Phtlodina aculeata (side view, corona expanded). 
Fig. 8. Male of Pedalion mirum. 
All these figures, save fig. 2, are reduced to scale from the beautifal plates 
in Hudson and Goss's Rotifera. 





PLATE XVI 
FORAMINIPERA 


Jum (a and b, lateral aspects). 
(a, lateral aspect ; 4, longitudinal section). 
Astrorhiza limicola (a, lateral aspect ; b, portion of the test more 
highly magnified, showing structure). 
Fig. 4. Haliphysema Tumanoni showing the pseudo-polythalamous 


ig. 5. Ibid. (group of specimens in situ). 
Fig. 6. Haplophragmium agglutinans (a, lateral aspect; }, longitudinal 


section). 

















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PLATE 4, 





x1750 








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THE MICROSCOPE 


CHAPTER I 
ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS 


To be the owner of a well-chosen and admirably equipped micro- 
sop, and even to have learnt the general purpose and relations 
of its parts and appliances, is by no means to be a master of the 
instrument, nor to be able to employ it to the full point of its 
efficiency even with moderate magnifying powers. It is an instru- 
ment of precision, and both on its mechanical and optical sides 
requires an intelligent understanding of principles before the best, 
optical results can be invariably obtained. 

We may be in a position, with equal facility, to buy a high-class 
microscope and a high-class harp; but the mere possession makes 
usno more a master of the instrument in the one case than the 
other, An intelligent understanding and experimental training are 
neelful to enable the owner to use either instrument. In the case 
uf the microscope, for the great majority of purposes to which it is 
applied in science, the amount of study and experimental training 
teded is by comparison incomparably less than in the case of the 
niusical instrument. But the amount required is absolutely essential, 
the neglect of it being the constant cause of loss of early enthusiasm 
and not infrequent total failure. 

In the following pages we propose to treat the elementary 
principles of the optics of the microscope in a practical manner, 
not merely laying down dogmatic statements, but endeavouring to 
show the student how to demonstrate and comprehend the applica- 
tion of each general principle. But in doing this we are bound to 
remember a large section of the readers who will employ this treatise, 
und to so treat the subject that all the examples given, or that nay 
le subsequently required by the ordinary microscopist, may be 
worked out with no heavier demand upon mathematics than the 
employment of vulgar fractions and decimals. 

In like manner, although we shall again and again employ the 
trigonometrical expression ‘sine,’ its use will not involve a mathe- 
matical knowledge of its meaning. The sines of angles may be found 

B 


| 


~| 


> 


2 ELEMENTARY PRINCIPLES OF MICROSCOPICAL oPrics 


Xa oa wi A table to quarter degrees is given in Appendix 
this book, which wl inthe majority of sams; en 
eer — sane dactatle teat ti the microscopist should 
ae more it 
have good mathematical knowledge ; but there are many men who- 
desire to obtain a useful knowledge of the principles of elementary 
who are without time or inclination, or both, to obtain the 
mathematical required. 
as a man who is without any accurate know! of 
mathematics may find time from a sun-dial by applying 
of taken from a tablo in an almanac, so by the 
table ofa ieee i Telomere and reliable» 
may have no. knowledge of trigonometry, 
rn wih np amon on wo 
peeaitiak ey! pen te arongt pene By 
AIRES through them. Re- 
i feiacoordanss wit Rheitwe fallow! Jaws, viz. :— 
1A ray which § in passing from a rare jum into a denser 
wd ciethpepry ats the normal, ic. the perpendicu- 
ithe eurtace or plane at which the two media join, will, on 
the denser medium, make a smaller with the normal. 
, a ray passing out from adense medium into a rarer one, 
tates umngis with the normal will, on emergence from the 
creatar with the normal. 
rin oe ium is the incident ray, and in the 


The Seat and her aae rays are always in the same plane. 
2, The sine of the angle of incidence divided by the sine of the 
ok of refraction is a constant quantity for any two particular 


iS 


i 


( 
ate 


pHa 
at 
Hu 


HI 


FE 
ta 


mason one of the media is air (accurately 4 vacuum) the ratio of 
these sines is called the absolute refractive index of the medium. 
known medium is denser than a vacuum it follows that 
the angle of the refracted ray in that medium will be less than the 
angle of the incident ray in a vacuum ; Pree ap the absolute 
refractive index of any medium is 

Farther, the absolute refractive index Hesse an: ie Pa substance 
will differ according to the colour of the ray of Tight employed. The 
refraction is least for the red, and greatest for the violet. The 
difference between these refractive values determines what is called 
the dispersive power of the substance. 

‘This will be understood by fig. 1. Let IC, a ray of light travel- 
ling in air, meet the surface A B of water at the point C. Through 
C draw N N’ at right angles to the surface of the water AB. The 
line NN’ is called the normal to the surface AB. The ray 1C will 
not continue ite | path throu; aoa the water in a straight line to Q ; but, 
because water is denser than air, it will be bent to R, that. is 
towards N’. The whole course of the ray will be IC R, of which 
the part IC is called the incident ray, and CR the rafracted ray. 


1 Vide Chambers's Mathematical Tabies. 


: 


4 ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS 


Now, aa sine TON =, and sine RON’ = tt, then, by 
Ligh 
Snollslaw, PO = 


FC 
As be taken in TC and RC if the points had been 
ioe jist we might he ret if 
expression. if we take two other points, K and E, such that 
KC=EG, and w the perpendiculars as before, we shall have 


ED 


a. KS * 1 
sine ICN = and sine RON'= 7.7, 


oS KC _ 

KC and therefore ee. = p- 
EC 

But SEES by construction, we can write KC for EC 


KS 


thus; EO — fe KC is cancelled, which leaves Ep™” 


ED 
KO 

As «can be experimentally determined for any two particular 
media, fe follows that if one of the other terms is Lissa eat the 
remaining term can be found, Thus, if « and the angle of incidence 
are known, the angle of refraction can be found ; and if » and the 
angle of refraction are known, the angle of incidence can be found. 
‘The unknown quantity can be found either geometrically or by cal- 
culation when the other two terms are given. 

It will, of course, be understood that, for the same medium in 
every case, a red ray would be bent or refracted less than a violet 
ray. The value therefore of p for a red ray will be less than that of 
yp! for a violet ray. As a practical illustration: The refractive in- 
dex for a red rey in erown glass is 1-5124 = p, and for a violet ray 
is 1/5288 = yp’, the difference being p’— =-0164. 

The refractive index for a red my in dense flint glass is 1-7030 
=" and for a violet ray is 17501 = p’, the difference being p!—p 
= 0471. 

Consequently there will be a tor difference between the bend- 
ing of the efrasted red and Siotatrayl in the case of dense flint than 
in the case of crown glass, the angle of the incident ray with the 
normal being the same in either case. 

here air (more correctly a vacuum) is not one of the media, 
then the refractive index is called the relative refractive index. 

The normal to a plane surface is always the perpendicular to it ; 
the normal to a spherical euxface is the radius of curvature, The 
angle of the incident ray and the angle of the refracted ray are 
always measured with the normal, and not with the surface. 

Fig. 2, a, 6, shows the normals A,B to both a plane and a 
‘spherical surface, C D. 

Inthe case of the spherical surface, B isthecentre of curvature,E F 


PROBLEMS ON REFRACTIVE INDEX 5 


is the incident ray in air, F G the refracted ray in crown glass. The 
angle A F Eis the angle of incidence, B F G the angle of refraction. 

Sine A F E divided by sine B F G is equal to the refractive index 
of air into crown glass, or, in other words, the absolute refractive 
index of crown glass, » ; thus in this particular case : 

(Problem) I. : 

sin AFE_ sin 45° -707_ 3 _ 
ain BFG sin 28°” 472 9 * 

This problem, however, is not actually needed by the reader of 
this book, for a table of 
absolute refractiveindices 
is given in Appendix B. 

It will be clear from 
the above that when the 
refractive index, absolute 
or relative, of a ray from 
any first medium is given, 
the refractive index from 
the second to the first may 
be found. 

Thus, the absolute re- 
fractive index p from air 
into glass being given as 
3 , find p’, the refractive 


index from glass into air. 





When the absolute — 
refractive indices of any 
two media are given, the 
relative refractive indices 
between the media can be 
found. 

‘Thus, the absolute re- 
fractive index p of crown 





glass is 13, and the ab. 7% ®—Thenormals tos plane and « curved 


solute refractive index y’ 
of flint glass is 1-6 ; find the relative refractive index yw” from crown 
to flint. 

(Problem) II. y _ yp’ _ 16 


The relative refractive index p:'”’ from flint to crown is determined 
by (problem) ii. : 


6 ELEMENTARY PRINCIPLES OF MIURDSCOPICAL OPTICS 


‘Let us now ee Se ee oe a 
posite direction. in the denser medium will now be the incid 
my, and FE in the rarer medium will be the refracted ray. N 
if the angle BF G be increased, the angle AP E will also be} 





Fi0, 8.—The phenomenon of total reflexion. (From the * Forces of Nature, 
poblikhed by Macmillan.) 


creased in a greater proportion, and the my F E will approach 
surface F D. 


‘When FE coincides with F D, GF js said to be incident at 
critical angle of the medium. When this critical angle is reac} 
none of the incident light will pass out of the denser medium, bu 





xviii EXPLANATION OF PLATES 


PLATE XIX 
ORIBATIDE 





Fig. 1. Leieroma palmiciactem | x about 40). eS 
Fig. 2. Nymph of same species. falls grown (x aboat 35). central 
ellipse with the innermost set of scales attached is the cast sarval dorsol 


abdominal skin. The other rows of scales belong to the successive nympha- * 
skins. 
Fig. 3. One of the scales more kighly magnitied. | 





CBEYLETIDE 1 
Fig. 4. Bostram and great raptorial palpi. with their appendages of Clsy-" 
Urtus renustissimus (x about 150). 
MYOBIID.E 


Fig. 5. Myobia chirnpteralis (female, x about 125). 


PLATE XX 
Claw of first leg of ame species, being an onsan for holding the hair of the 
bat. 
GAMASIDE 
Fig. 2. Gamasus terribilis (male. x 30). 4 species found in moles’ neste, ~ 


ANALGIN.E . 


Fig. 3. Freyana heteropus (male, x about 93, a parasiteof the cormorant). - 
Fig. 4. Sareoptes srabiei (the itch mite, x about 150, adult female). 





ACTION OF A PAIR OF PRISMS IL 





é 





Fro. 8.—Action of a pair of prisms with their bases in contact on 
parallel light. 








Fro, 9.—Action of a pair of priams with their apices in contact on 
parallel light. 





THE FOCI OF LENSES 13 


focus of a converging lens, the rays are brought to a focus beyond 
the principal focus on the other side of the lens, The nearer the 
radiant is to the principal focus, the farther away will be its conjugate 
focus from the other principal focus. In other words, there are two 
ants in the axis such that if the object is one point its focus will 
the other ; these are reciprocal one to the other. These points, 





Fu. 1t—Biconves, Plano-convex, Fia, 12.—Biconeave, plano-concave, 


converging meniscus 1d divergis i lenses. 
(From the "Forces of Nature.) (From the * Forces of Nature.) 


the focal distances of which can always be calculated, are known as 


Should the radiant be ata distance from the principal focus equal 
to the focal length of the lens (i.e. twice the focal length from the 
lens) then its conjugate will be at the same distance from the focus 








Fiu,18—A radiant at the principal focus of a biconvex lens makes the refracted 
Tays parallel. 








Fio. 14.—A radiant placed beyond the principal focus causes rays to converge 
beyond the principal focus on the other side of the lens. 


on the other side of the lens (i.e. twice the focal length from the lens). 
In other words, when the object and its image are equidistant on 
either side of the lens, they are equal to each other in size, and 
are four times the focal length of the lens apart. 


14 ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS 


This law forms a ready means of determining the focal length of 
alens. An object is Placed in front of alens and the distances 
between this object and the lens and a screen to receive the image 
of the object are so adjusted that the image of the object becomes equal 
in size to the object itself. The distance of the object from the screen 
divided by 4 gives the focal length of the lens. 

Tf a radiant be placed between a lens and its principal focus, the 
rays on the other side of the lens are still divergent, and will never 
meet in a focus on that side. This is seen in fig. 15 ; but if they are 
traced backwards, as in the dotted lines of fig. 15, they will then 





Fro. 15.—Rays diverge when a radiant is placed between a lens and its 
principal focus. Focus of divergent rays is virtual. 


meet in a point. This is called the virtual conjugate focus of the 
radiant. The principal focus of a concave (or diverging) lens is 
shown in fig. 16. It will be seen that the principal focus is not 
real but virtual. Parallel rays falling on a concave lens are rendered 


SO 





16 ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS h 


grasp of them, to draw such a lens, and trace the paths of two rays 
through it, one near the axis, the other near the edge ; then do = 
same with the lens reversed. 

Formula for spherical aberration : ' 


= ¥ e-1( dy (tl _ 1) (1_1)* ‘ 
sat eats NG at) hae 
whero f= principal focal length ; y= semi-aperture; = ref. 


indox ; und 7, —r’, radii. 





r= -9, 


In an oqui-convex of crown, where p= 5, 


yo. 
st ie Sa 


Ii a plano-convex of crown, where p= 3, —r' = @, + =f 


af=—1 . %. Here parallel mys are incident on the convex 


i 
xurface, But when parallel rays are incident on the plane surface, 
3 fy 9 yy, 

1 8F= — 9 + 95 consequently the sphe 





rient nberration is four times as great (see figs. 17 and 18). 
When —r's: ar, and j= 1°69, the plano-convex becomes the 
form of minimum aberration, 


In w crossed? biconvex lens, where —r =6r, and p = 3, 


In 
MW 
curved xurface, 
Vormula for finding the principal focus F of a lens equivalent 
to two other lenses whose foci are f; /” and their distance apart d: 


ee 


ifs 


‘ ", the parallel rays being incident on the more 








18 ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS 


tion of R and V would only be half ax great as that effected by the 
prism in the figure, 

Then if another prism were made of the same material as that 
assumed in fig. 5; but with only half the refracting angla, viz. 25°, 
the dispersion between R and V would also be but half that repre- 
sented. Also a prism having 50° of refracting angle gives the same 
amount of dispersion as that from a prism of 25° of refracting angle, 
but of twice its dispersive power. 

‘Under these conditions, when one prism, exactly like another in 
angle and dispersive power, is placed close to it in an inverted 
position, the dispersion of the first prism is entirely neutralised by 
that of the second because it is precisely equal in amount aud 
opposite in power. 
This will be under- 
stood by a glance at 
fig. 20, But it will 
be seen that not only 
isdispersion reversed, 
but refraction also 
is neutralised, the 
emergent ray being 
parallel “to the in- 
cident ray. Therefore 
theequaland inverted 
system of prisms can 
be of no possible use 

Fio, 20,—Becomposition of light by prisms, (Prom. ‘0 the practical opti- 

‘the ' Forees of Nature’) cian in the corree- 

tion of lenses because 

the convergence and divergence of rays are both essential to the 

construction of optical instruments, The dispersion, in fact, must 
be destroyed without neutralising the refraction. 

Suppose we take a prism with an angle of 50°, composed of glass 
having a certain dispersive power, and invert next it a prism of 25° 
angle, composed of glass having twice the dispersive power of the 
former. Dispersion will be manifestly destroyed, because it is equal 
in amount and opposite in nature to that possessed by the prism of 
50°; but the prism with an angle of 25° will not neutralise all the 
refraction effected by the prism of 50°. 

These conditions plainly suggest the solution of the problem, for 

rt of the convergence ix maintained while the whole of the 
ispersion is destroyed. 

The spherical lenses which answer to these prisms are a crown 
biconvex, fitting into a flint plano-concave of double the dispersive 

wer. 

It has been pointed out above that all the other colours lie in 
their proper order between the rays R and V (fig. 5). Let us select 
one, green, and represent it by G. Now if G lies midway between 
R and V in the prism of 50° of angle, and also between R and V in 
the prism of 25° of angle, its dispersion will also be neutralised. 
‘This means that when the dispersion between the three colours in 














20 ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS 


tinct points, Xand Y, If there were no cover-glass all the rays would 
diverge from O,and then the objective would require to be 
Splanutie, "This word (derived trom ae a sar 





Pa eh eae Sree eae ons Nha conrectionn of an 


thatall therays passing through a lenssystem are brought to an identi- 
ealcnjugte fon, as shown in fig. 22, But as affected by the cover- 
glass the marginal rays diverge, apparently, from a focus nearer the 
objective than the central rays ; therefore the objective, to meet this 
condition, must be what is called wnder-corrected ; n condition pre- 
sented in fig. 25, so as to focus both these points at once. Here the 


, 
Fro, 29—Aplanatic system, Fio. 98 —Under.corrected syxtam, 


curvature of the surface of the crown lens being increased, the flint 

plano-concave is not sufliciently powerful to neutralise nll the 
spherical aberration of the crown, As a consequence the peripheral 

rays are brought to a focus at F’, while the central rays pass on to 
F, This is what is meant by ‘under-correction’ in an object-glass, 

In fig. 24 the reverse condition 

is presented, for the incident curve 

a! of the crown lens has been flattened, 

while that of the flint has been 

deepened, which increases the cor- 

Fi. 2—Over-cormeted system.  Tective power of the flint, and thus 

destroys the balance af the com- 

bination in other directions, The rays passing through the periphery 

of the combination will be brought to a focus I’, while the central 
rays will be focussed at F. This is what is known as over-correction. 


22 ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS 


and B, the distance of its conjugate from F’, the other principal 
focus on the other side, then : 


AB=FF; 
or, in an equiconvex lens, 
AB=F*, 
In an equiconvex lens of crown glass p= 1:5 if F = radius of - 
curvature. But in a plano-convex lens of crown glass p=1°5 if 


F = twice the radius of curvature. 

In the above formula the thickness of the lens has been neglected. 
In thick lenses, however, its effect must not be disregarded, even if 
only approximate results are required. A very approximate determi- 
nation of the principal focal length of an equiconvex lens may be made 
hy subtracting from the result obtained by the foregoing formule 
one quarter of the thickness of the lens. 

Example.—Equiconvex lens of crown glass p=1-5, r= }4, thick- 
ness=}. By above formula F=4. Subtracting from this one- 
quarter of the thickness of the lens we get F=yy as the distance: 
letween the focus and the surface of the lens. This is only qs inch 
from the truth. Tf the lens were a sphere it would be accurate, 

Tn the case of a plano-convex lens the principal focus on the 
convex side is equal te twice the radius as above, but on the plane. 
side two-thirds of the thickness of the lens must be subtracted 
from it. 

Example.—Tn a hemispherical lens of crown glass «= 1-5, radius 
=1, thickness= }, the principal focus on the convex side will be 
one inch from the curved surface and on the plane side § inch from 
the plane surface, 

Similarly, in an equiconeave Jens subtract from the principal 
focal length, obtained by the above formula, half the thickness of 
the lens. In other words, measure the focal length from the centre 
of the lens. The focus is of course virtual. 

Buta plano-concave lens follows the plano-convex. 

















The principal 





24 ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS 


suing from every point along A B may be traced, and will be found 
to have each one its respective conjugate lying on C D, so the cos- 
jugute of Bis at D. Hence it is at once manifest that an inverted 
conjugate image of the object A B is formed at CD. Further, it 
will be noticed that, although the object is straight, the image of it 
is curved towands the lens. : 
Ig the object AB had been curved, so that it presented a conver 
aspect to the lens then its conjugate image CD would have bee 
more curved ; but if AB had been slightly concave towards the lens, 
then its conjugate would have been straight. 
ated, the point C has been determined by tracing 
the vefraction of two mys! AF and AH, through the lens. Another 
method is, however, often employed 
In every lens there i hich is called its optical centre. 
> point is sueh that any ray h in its refraction through the 
= paises through this point. in a directi 
its path before inmengence. 
cal purposes are often assumed to be of insensible thickness, it has 
become the prictice to dimw any ray passing through the optical 
centre of the lens a straight line. " Obviously, if the lens has sensible 
Ness the cannot be considered a straight line, and in the 
microscope, where the lenses are very thick in proportion to the 
length of their foci, this method will lead to much error. Of course, 
in those eases where it cain be taken as a straight line, it saves the 
trouble of computing a second ray to intersect the first, as any ray 
interseeting the straight line will determine a conjugate focal point. 
Ln the upper part of 6 the two rays, AF and AH, are 
ved through the lens to determine the point C, but in the lower 
of the tigure only the ray B K is traced, and the intersection of 
y by the straight line BD passing through the optical centre 








gives the point D, 

2. An image 1 to be virtuad when it cannot be received on 
W sereen, 27 shows how a virtual image is formed. The 
lottors are the same as in the preceding figure, so as to show the 





26. ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS 


In the formula N =! the amplification of one and the sama‘ 


system varies with the length of /, or the ‘distance of vision a 
an arbitrary conventional value of J (ie. 10 inches, or 250 mm)’ 
must be introduced in order to obtain comparable figures. The 
ctual ‘linear amplification’ of a system is, of course, different ix } 
the case of a short-shorted eye, which projects the image at a dis! 
tance of 100 mm., and a Tong-sighted one, which projects it s — 
1000 mm. Nevertheless, the ‘amplifying poteer’ of every system 
always the same for both, because the short-sighted and the long-sightod 
observers obtain the image of the same object under the same viewel 
angle, and consequently the same real diameter of the retinal image. j 
That this is so will be seen from fig. 28, where the thick lines show L 




















Fio. 28.—The amplifying power of a lens. 





28 ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS 


is found practically that ‘immersion’ objectives can be constructed 
with magnifying powers sufficiently high, and apertures sufficient 
large, for the majority of the ordinary purposes of scientific investi- 
gation, without any necessity for cover-adjustment ; being originally 
adapted to give the best results with « covering glass of suitable 
thinness, and small departures from this in either direction occasion- 
ing comparatively little deterioration in their performance, But 
beyond all these reasons for the superiority of the ‘immersion 
system’ is, as will be presently seen, the fact that it admits into the 
lens a larger number of ‘diffraction spectra’ than can be possibly 
admitted by a lens working in air; and upon this depends the 
perfect presentation of the image. 

‘The immeraion syrtem has still more recently been advanced upon 
by the application of a principle which lies at the root of the optical 
interpretation of the images which modern lenses present, and 
which has greatly increased the value of the microscope as a scientific 
instrument. It'is an improvement that primarily depends upon & 
correct theoretical understanding of the principles of the construction 
of microscopical lenses, and the interpretation of the manner in 
which the image is realised by the observer. The ‘late Mr. Tolles 
was the first to adopt this system, as we point out subsequently; 
but it was to Professor Abbe we are indebted for its practical appli- 
cation, through whom it is now known as the homogeneous system. 
‘The idea of realising the various advantages of such’ a system by 
constructing a certain class of homogeneous objectives had, Professor 
Abbe says,’ ‘for some time presented itself to his mind.’ ‘The 
matter assumed, however, subsequently, a different. shape in conse- 
quence of a suggestion made by Mr. John Ware Stephenson, . 


of London, who independently discovered the principle of homoge- 
neous immersion.” ? 

This method consists of the replacement of water between the 
covering glass of the mounted object and the front surface of the 
object-glass by a liquid having the same refractive and dispersive 








30 ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS > 


the object-glass and eye-piece. But this must also be aided in | 
endeavouring to secure the most perfect ‘critical images ’ by a body- 
tube provided with rack and pinion motion. When the two ar 


combined, if the object-glass is of perfect construction and of lates 


forin (apochromatic, results never before attainable can be 
with comparative ease. And this, be it observed, does not in the | 
least compromise our admission of the perfect accuracy of the 
theoretical principle of the homogeneous system. 

With such evidence of advance in the optical construction of 
microscopes, lependent apparently on such accessible conditions, the 
question of what is possible in the future of the instrument no doabt 
obtrudes itself ; that, however, can only be considered as having 
application to the area of our present knowledge and resources, It 
is impossible to forecast the future agencies which may be at the 
disposal of the practical optician. To photograph stars in the im- 
measurable amplitudes of space, absolutely invisible to the human 
eye, however aided, was hardly within the purview of the astronomers 
of a quarter of a century ago; that there may be energies and 
methods discoverable by man that will open up possibilities to the 
eager student of the minute in nature which will just as widely 
overstep our present methods of optical demonstration, there can be 
little reason to question. But it is no doubt true that with the in- 

nil media now at the disposal of the practical optician 
no indefinite and startling advance in microscopic optics is to be 
looked for. The ‘atom’ is infinitely inaccessible with any conceiv- 
able application of all the resources within our reach. But optical 
improvement of great value, bringing nature more and more nearly 
and accurately within our ken and reducing more and more certainly 
the interpretation of the most difficult textures and constructions in 


the minutest accessible tissue to an exact method, is certainly 
within our sight and reach. It is not a small matter that the homo- 
geneous lenses were, in a comparatively short period of time, carried 
from a N.A. of 1:25 to 1:50; and this carried with it the capacit 


32. ELEMENTARY PRINCIPLES OF MICROSCOPICAL OPTICS 











co-operation of the optical workshops of Zeiss, have undertaken the 
laborious and prolonged investigation into the improvement of 
optical glass, to which we have alluded ; the result has been the pro- 
duction of ‘crown ' and * tlint glass possessing exactly the qualities * 
forvshown as indispensable by Abbe. 

Ry chemical, physic . and optical research of a most laborious 
nature, and by Sererounet ¢ observations of numerous experimental — 
fusions systematically carried out with a large variety of chemical 

nts, the relation between the vitreous products and their 
chemical composition has been more closely investigated. 
In the crown and flint glass produced up to the time of these - 
investigations, the uniformity of property arose from the relatively 
small number of materials employed. Aluminium and thallium, 
with silica, alkali, lime. and lead. formed the limit. By the use of 
hemical elements, especially phosphoric and boric acid as the 
sutial constituent fluxes in the place of silica alone, fit 
and crown gliss have been produced in which the dispersion in the 
di rent partes ¢ rth trum is nearly proportional ; so that in 
chromatic combinations it is now a question of detail and practical 
optics to eliminate almost entirely the secondary spectrum. On the 
other hand, the kinds of hich can be used for optical purposes 
i ii it, while the mean index of re- 
tions can be given to the 
dispersion or to the refra < while the dispersion remains 
constant. A high index of refraction is no longer of necessity ae- 
companied by a high dispersion in flint glass, but may be retained 
i with a low degree of dispersion. 
consequence of this is that both the imperfections 
+ from an objective constructed of ordinary crown and 
flint glass ean be. and. ye been, eliminated, and the secondary 
spectrum annulled; it removed and reduced to a residue of 
ehromatism of a tertiary character, while the chromatic difference 
of spherical aberration can be eliminated or completely corrected 




































and therefore it allows of correction by the @ special con- 
struction g etwas eyo dierences ot i 
power for at 0 eye-piece is so constructed as to 
cmap pacers tbe dere sult, and, as we have 
ot colour are 
‘ The of the eye-pieces for this system of objectives 
hus been es by Abbe, and depends on the increase in the 
total magnifying power of the mi: obtained by means of the 
b ilieederl with that given by the objective alone. The 
which how many times an eye-piece increases the 
magnifying of the Sin ich ep rection nena eee 
tube, gives: measure ‘eye-piece magnification, and a 
in ape dina e for rational numeration.' 


From their properties these are known as ‘compensating eye- 


pieces.’ 
The ing is a fair typical selection of the objectives and 
pop nica from the workshops of Carl Zeiss, of Jena, on 


portant aystem, viz. ; 
Apochromatic Objectives. 
Apertare Foot Length English Equivalent 
030 240 mm, 2 inch. 


030 wo, 
Dy. © 6 © «fs 8 120, 


065 oD . 

005 oo. rf 

0-95 40) - 

Water Immersion... 125 25 5 . 
3 140 30 | a 

Homogeneous Immersion {i460 20 7 met 


Compensating Kye-yieees for English Bodies 
3 4 8 2 a8 27 


Tt _is of interest to note that Messrs. Powell and Lealand, on 
receiving the special glass from Germany proceeded immediately to 
the luction of a 'y-inch objective with compensating eye-piece 
on # formula devised by Mr. T, Powell, which were supposed to 
be apochromatic. The workmanship was of the high class for which, 
in the manufacture of lenses, that firm have become distinguished ; 
and this objective has, together with those subsequently produced, 
brought out admirably the quality of the work; for we now know 
that the perfect apochromatic objective requires fluorite lenses in 
its combinations to obtain the needful corrections, But without 
the use of these this firm came so near the earlier apochromatic 
objectives of Zeiss, for visual purposes, that it was not easy to discover 
their deficiency. This was due entirely to perfect workmanship. 
‘The same firm have since produced a eatin lens on the same 

tem, having a N.A. of 1°50, with a power of 4th of an inch. 

bject-glasses are also now made by other makers, English, Euro- 


1 ‘On Improvements of the Microscope with tho aid of new kinds of optical glass” 
(Abbe), Journ. 2.AL8. 1897, p. 25 et sey. 








FORMUL2 RELATING TO REAL IMAGES 35 


pean, and American, known as ‘apochromatic’; but we doubt, in 
the majority of cases, if the apochromatism is attained, for it has 
only recently been made known that, in addition to the special glass 
used in their construction, the Abbe apochromatic systems had in- 
serted also the fluorite lenses referred to above, which materially 
affects the result. It is remarkable, however, how near some makers 
have brought their results to those of Abbe without the advantages 
of the fluorite lens. With this material employed in their con- 
struction Messrs. Powell and Lealand are making beautiful object- 
glasses. We have recently used a new }-in. made by them, to which 
-we have seen no successful rival. 





CHAPTER If 


THE PRINCIPLES AND THEORY OF VISION WITH THE 
COMPOUND MICROSCOPE 


We are now to enter upon the ication of the optical’ 
which have been explained and illustrated in the foregoing 
Siests ai eomeiee each ‘ind hay ae ae ad: 
as it ing its i vant 
to the studentof nature, Their feenittal diftarenon consists in thi 
that in the former, the rays of light which enter the eye of the 
observer proceed directly from the object itself, after having been 
subjected only to a change in their course, as we have shown by 
fig. 26, which fully explains the action of the simple lens ; whilst in 
the peat microscope an enlarged image of the object is formed 
by one lens, which image is magnified to the observer by another, 
as if he were viewing the object itself. In the compound micro- 
scope not less than two lenses must be employed : one to form the 
enl image of the object, immediately over which it is placed, 
and hence called the olject-glass ; whilst the other ap magnifies 
that image, and, being interposed between it and the eye of the 
observer, is called the rye-glass, A perfect object-glass, as we have 
seen, must consist of m combination of lenses, and the eyeglass is 
‘best combined with another lens interposed between itself and the 
object-glass, the two together forming what is termed an eye-pieos, 
The compound microscope must be the subject of careful and de- 
tailed consideration ; but it must be remembered that the shorter 
the focus of the simple magnifying lens, the smaller must be the 
diameter of the sphere of which it forms part; and, unless its 
aperture be pi jonately reduced, the distinctness of the image 
will be destroyed by the spherical and chromatic aberrations neces: 
sarily resulting from its high curvature, Yet notwithstanding the 
loss of light and other drawbacks attendant on the use of single 
lenses of high power, they proved of great value to the older micro- 
scopists (among whom Lecuwenhock should be specially named), on 
account of their freedom from the errors to which the compound 
microscope of the old construction was necessarily subject ; and the 
amount of excellent work done by means of them surprises everyone 
who studies the history of microscopic inquiry. An important im- 
provement on the single lens was introduced by Dr. Wollaston, who 
devised the doublet, still known by his name, which consists of two 
plano-convex lenses, whose focal lengths are in the proportion of one 
to three or nearly so, having their convex sides directed towards 


Ci 





38 VISION WITH THE COMPOUND MICROSCOPE 


CO ON pee lena," ‘Dele i aeaky tuodly 
Saeed cient fot and mde jet which will readily 


a 
car ile piase ‘of the lens and then to hold it up to the 
ee tno hand lenses we have yet seen will compare with the 
‘inheil ‘loups’ of six and ten diameters made by Zeiss, and 
Reichart’s loups. 
For the oni i of ic dissection single lenses 


inch focus answer very well. But when hi 
powers are required, and when the use of even the lower powers is. 
continued for any length of time, great advantage is derived from 
the employment of achromatic combinations, now made expressly 
for this by several opticians. The Steinheil combinations. 
give much more light than single lenses, with much better definition,, 
a very flat field, longer working distance (which is very important 
in minute dissection), and, as a consequence, greater ‘focal depth” 
or ‘penetration,’ ic, a clearer view of those parts of the object 
which lie above or below the exact local plane. And only those 
who have carried on a piece of minute ond difficult dissection 
through several consecutive hours can appreciate the advantage in 
comfort and in diminished fatigue of eye which is gained by the 
substitution of one of these achromatic combinations for a single 

—— lens of equivalent focus, even where the use of the 
former reveals no detail that is not discernible by the 
latter. 

Although not strictly its position, it is convenient 
here to refer to what is known as the ‘ Briicke lens’ ; 
it is much used on the Continent, but does not ap- 
pear in any English treatise we have seen, It has 
two lenses for the objective, and a concave eye lens, 
It is illustrated in fig. 29. 

To remedy the inconvenience of the lens being too 
close to the object in all but low powers, Charles 
Chevalier, in his ‘Manuel du Micrographe’ (1839), 





*iptdcko lens, proposed to place above a doublet a concave achro- 


matic lens, the distance of which could be varied at 

pleasure. ‘The effect of this combination is to increase the magnifying 
[dra and lengthen the focus. Thus arranged, this instrument will 
the most powerful of all simple microscopes, and the space 
available for scalpels, needles, &c. will be much greater than 


40 VISION WITH THE COMPOUND MICROSCOPE 

much better to vary the power by omploying object-glasses of dif- 
ferent i of focus forming an which 
chara lee ese sae iat, Aer petra ee age 
SE, aed alas Calpe Seeger pa ary 
Sececieeiaial wis a nines: the object should 
be so nearly a) tulle the objet ands dimenns ae Pop 
auch eee ol dimensions are propor- 
smn mode increased may be 


eS eae foie result from the change = the pro- 
of the ol of which an imagecan be formed 
must be diminished, and poehananitiy ne gt spread over that 
image must be ly lessened. But, as we have stated, this 
independent ot te Pepe oe 


and total egrs 
upon :) the focal of the eye- 
Seo eons a by the brant ail 
tee i Mees taaitsbe onupoand ciovenra byl meant 
ion, is, the ol ive 
In this figure the optical portion, that is, the objective and 
piicaiiare ita 30 thai tall size, but the distance between these 


i “to the exigencies of been much curtailed. A low- 
Sieve sales i very tates ets = scm: 
pter V.) has been introduced to show 

feng epi peed 


‘The objective is a copy of an old Ross l-inch of 1856. The 
incident front (that is, 1 the lens on which the incident beams from 
the ic oe first strike) is a convex of long radius ; the incident sur- 

the flint lens of the back combination is ‘concave of very 


bo ear ae fact about twenty inches. 
‘he object F only rays drawn from one side in order that 


a clearer perception of the path of the rays may be seen, This pair 
of rays passes from the arrow (object) through the combination of 
tenses forming the objective, giving an inverted real image at AB, 
This i i » in fact, has a convex curve towards the eye-piece ; this 
« ‘4 position that will tend to increase the curvature of the virtual 
image CD given by the eye-picce. Three rays are drawn through 
the eye-piece, a gives a magnified virtual image of the real 
eee from the ‘objective, i in Cad to suggest that with the eye-piece 
is a commencement, as it were, de novo, the in’ image 
ae B) at the diaphragm of the eye-piece being the subject of still 
lurther and often great magnitication. 

Tn addition to the two lenses of which the compound microscope 
may be considered to essentially consist, it was soon found needful 
to introduce another lens, or a combination of lenses, between the 
object-glass and the image formed by it, the purpose of this being 
to change the course of the rays in such a manner that the image 
may be formed of dimensions not too great for the whole of it to 
come within the range of the eye-glass. As it thus allows more of 
the object to be seen at once, it has been called the field-glass ; but 
it is now usually considered as belonging to the ocular end of the 
A aera the eye-ylase and the field-glass being together termed 

or ocwar. Various forms of this eye-piece have been 
ages by ‘different opticians, and one or another will be preferred. 











compound microscope. 


Fro. 30,—Path of a ray of light through a modern combination of lenses for 


‘construction of the compensation eye- Abbe, 
the ale mierp i object- 
to the performance of which it is desired to give the greatest 
Sees ts nations tag Tiace he aoe 

ie 

Rel eatagea sink te testcase of 
This eye-piece, with others, will be considered in detail 
in the chapter (v.) given in part to their consideration ; but this 
eye-piece consists of two: Con’ with their plane sides 
towards the eye. A ‘stop’ or diap BB, must be placed 


8! 
corrected by it, With the apochromatic lenses of the highest and 
best ate, (see Chapter V.) no amount of obtainable eye-plecing, if 
it be of the ‘compensation * form, can break down the image. 
editor has tried in vain to break down the image formed by a 
24 mm., a 12mm., a 6 mm., and a 4 mm., all dry apochromaties by 
Zeiss, ancl especially with a }th by Powell and Lealand. It is, how- 
ever, & matter of moment and interest to note that with good objec- 
tives of the ordinary achromatic construction of large N.A. the com- 

‘ing eye-pieces give better results than Huyghenian, 

But of the old form of achromatic object-glass it is true of the 
majority that they will not bear high eye-piecing. ‘B’ isa con- 
venient and eye-piece. For viewing large flat objects, such as 
transverse sections of wood or of echinus-spines, under low magni- 
fying powers, the eye-piece known as Kellner’s may be employed, 
but there is little advantage to be gained. This construction will 

fully described in Chapter V. A flat, well-illuminated field of as 
much as fourteen inches in diameter may thus be obtained with very 
little loss of light; but, on the other hand, there is a very 
serious falling off of defining power, which renders the Kellner 
piece unsuitable for objects presenting minute structural details ; 
and it is an additional objection that the smallest speck or smear 
upon the surface of the field-glass is made so unpleasantly obvious 
that the most careful cleansing of that surface is required every 
time that this eye-piece is w Hence it is better fitted for the 
occasional display of objects of tho character already specified than 
for the scientific requirements of the working microscopist. 

A solid eye-piece made on the principle of the ‘Stanhope’ lens 
is sometimes used in place of the ordinary Huyghenian, when high 
magnifying power is required for testing the performance of objec- 
tives. The Sie surface, which has the lesser convexity, serves as 
a ‘tield-glass’ ; whilst the image formed by this is magnified by the 
highly convex upper surface to which the eye is applied, the advan- 

‘supposed to be derived from this construction lying in the 
abolition of the plane surfaces of the two lenses of the ordinary eye- 





VISION WITH THE COMPOUND MICROSCOPE 


receives, The apparent problem of is to be able, 
‘by means of lenses, to gat upg rng to as of the 

erases prenilie general manner in which lenses 
in this we have endeavoured in an elementary manner to 


& 


: ne 


i 
i 
i 
f 


¥ FE 

it 

fi 

pee 
t 

i 

Ht 

; 

: 

2 


Fesey unknown. _— re ew 
‘a8 we shall subsequently see), even with objectives employ: 
only with air, the angle of the radiant pencil did not afford a true 
-comparison ; when immersion objectives were introduced—objectives 
in which water or cedar oil the air between the objec- 
tive and the upper surface of the cover of the mounted object— 
the use of angles of aperture became in the utmost degree misleading; 
for different media with different refractive indices were cnploye, 
and the angle of the radiant pencil was supposed not only to H 
of a comparison of two apertures in the same medium, but also to 
be a standard of comparison when the media were different. It 
was, in short, believed that an angle of 180° in air represented a 
Jarge excess of aperture in comparison with 96° in water and 82° in 
balsam or oil, denoting, in reality, what was believed to. be the 
macimum aperture of any kind of objective, which could not, it 
was held, be exceeded, but only equalled, by 180° in water or oil ; 
in other words, that a radiant pencil has exactly the same value, 
when the angles are equal, no matter what the refractive index of 
the medium through which the pencil might be passing. 

But to a thorough physical and mathematical study of the ques- 
tion such as that in which Professor Abbe engaged, it soon became 
apparent that even in the same medium the only exact method of 
comparison for objectives—when the fundamental phenomena of 
optics (which the cule opticians had disregarded) were taken into 
account—was not a comparison by the angles of the radiant pencils 
only, but a comparison by their sines ; while, when the media are 
different, the indices of those media would be found to form an 
essential factor in the problem ; for an angle of 180° in air is equal 
to 96° in water or 82° in oil ; hence three angles might all have the 
same number of degrees and yet denote different values, according 
as they were in air, water, or oil 

Thus there might be large divergence of aperture in two or 
more cases while the angle was identical, and from this the greatest 
confusion was not only possible but was realised. 

Ac solution of the difficulty was (as we have indicated above) 
discovered by Professor Abbe; and it is to Mr. Frank Crisp’s 


the same linear opening, twice as many rays as the latter, 

‘beeause the ification of the image at one and the same distance 

is doubled, the same number of rays ently are admitted 

the higher power from a field of half the diameter. And this 

hold eitivonbee the medium around the object is the same 

in the case of both objectives or different ; for an immersion system 

and a dry system always give the same amplification when the focal 

iene it the 1 for all kinels of obj 

us we arrive at general proposition for all ki objec- 

tives, First, when the power is the same, the admission of rays 

varies with the diameter of the pencil at its emergence. Secondly, 

when the powers are different the same admission requires different 

ings in the paveostian of the focal lengths, or, conversely, with 

the same opening the admission ix in inverse proportion to the focal 

length—that is, the objective which has the wider pencil relatively 
to its focal length has the larger aperture. 

Thus we see that, just as in the telescope the absolute diameter 
of the object-glass defines the aperture, so in the microscope the 
ratio between the utilised diameter of the back lens and the focal 
ae of the objective defines its aperture, 

jis definition is clearly a definition of aperture in its primary 
and only legitimate meaning as ‘opening’—that is, the capacity of 
the objective for admitting rays from the object and transmitting 
them to the image ; and it at once solves the dithculty which has 
always been involved in the consideration of the apertures of 
‘immersion objectives. 

So as the angles were taken as the proper expression of 
aperture, it was difficult for those who were not well versed in 
optical matters to avoid regarding an angle of 180° in air as the 
maximum aperture that any objective could attain. Hence, water- 
immersion objectives of 96° and oil-immersion ctives of 82° 
were looked upon as being of much /exs aperture than a dry objective 
of 180°, whilst, in fact, they are all egua/, that is, they all transmit 
the same rays from the object to the image. Therefore, 180° in 
water and 180° in oil are unequal, and both are much larger aper- 
tures than the 180° which is the maximum that the air objective can 
transmit. 














43 ‘VISION WITH THE COMPOUND MICROSCOPE, 


— back “yer ratio of the semi-diameter 

ks take Sg Sie Peete pn be 
opentrar the medium (n) in front of the objective, 
Sten sean and 15 for oil or 





oe eos 


Let 0 and OF 32) be the conjugate aplanatic foci of a wide- 
Euchre Voce ‘eaten p pean ero 


cre pce ae ere ip pers of Professor Abbe from German 
English the ayzsbols have been Tetainae In the wanamuie or 
A 


BA. of objectivesn xia $=19 x-a73=36, wal wa t$ S73="80=N.A. of objoctire, 


Angular aperture of 
‘objective = 35° 





WA. of condoning =a* sini wE=10 x t= 08, pial p's 10 9080 86. =N.A, of condenser, 
B 
Yoo. At—idemity of «tue (Games 2 Lr feces with sing (English). Also NA, ond 


Abbe's thoorles and demonstrations presented in the following pages the Editor has 
searoely felt justiGod in altering thin, expecially ms the German form of symbol ob- 








i 


due appreciation 

however, ‘numerical’ aperture, which gives ‘60 for the dry 
ive, ‘90 for the water-immersion, and 1°30 for the oil-immersion, 
Saaneis spec esas iedintal iately a) psa nota, See 


instance, that the aperture of the water- somewhat 
than that of a dry objective of 180°, and that the erent tee 
ion exceeds that of the latter by 30 per cent. 


‘When these considerations have been appreciated, the advantage 
by immersion in comparison with dry objectives is no 
obscured, Instead of this advantage consisting merely in 

Le, absence of correction-collar, it is seen 


1. There exists then « definite ratio between the linear ing 
and the fies length Bs a system, which ees nosrelyaia S 
dent of composi armngement, © system, 
determined by tie above-mentioned aperture equivalent of the 
admitted cone of mys. When the equivalent is the same we have 
always the same proportion of ing to focal length, whatever may 
be the particular arrangement of refracting media in the system. 

2. If the objectives whose apertures are compared work in the 
sone medium, and admit angles of, say, 60°, 90°, 180°, their aper- 
tures are not in the ratios of those numbers, but are as ‘50, 70, and 
10. The 180°, for instance, does not represent three times the aper- 
ture of the 60°, but tivice only. 

3. If the objectives work in diffrent media, as air and oil, the 
latter may have an aperture exceeding that of a dry objective of 
180° angle. For with the dry objective the refractive index (n) and 
the sine of half the maximum angle (uv) both =1, so that m sin 
= 1also, whilst with the immersion objective n is greater than 1 (say 
15 for oil), and the angleu may therefore be much less than in the 
case of the dry objective, and yet the value of the expression » sin « 
(i.e. the aperture) may be greater than 1-0, 

The two latter deductions are so directly opposed to what was 

ited by the older opticians and microscopists that a closer if 
titled consi leration of some of the points which bear upon this branch 
of the subject may here be serviceably summarised, 

Take, first, the case of the medium being the same, 

Difference of aperture involves a different quantity of light ad- 
mitted to the objective provided all other circumstances are equal. 
Hence the question of aperture leads to the consideration of the photo- 
metrical equivalent of different apertures or aperture angles. It is 
not of the essence of the problem, but it affords an additional illus- 
tration of numerical aperture, and is thus of great service in its 
exposition. It is manifest that aperture jaan bs taied on quantity 











2 VISION WITH THE COMPOUND MICROSCOPE 


which the ray is sent out. The rays are more intense in proporti 
are inclined to the surface which emits them, so that a p 

n proportion as it is taken close to or is removed from 
perpendicular, A pencil is not, therefore, correctly represented 
but by fig. 34, the density of the rays decreasing continu 

from the vertical to the horizontal. 

Owing to the different emission in different directions, the quan) 
tities of light emitted by an element in the same mediom in come 
of different angle such as w and w’, fig. 35, are not in the rte 
of the solid cones, as would be the case with equal emissiony 
but in the ratio of the squares of the sines of the semi-angles, so that.) 
the squares of the sines of the semi-angles constitute the true measite) 
of the quantity of light contained in any solid pencil. 

When, therefore, the medium is the same, it is seen that they 

















Ors 
~~ 





‘The unequal emission of rays. 


Fro. 








is no contradiction between the measure of the aperture of an ob- 
jective (n sin u) and that of the quantity of light admitted by th 








2eN WITH THE COMPOUND MICROSCOPE 



























lished, by distinguished research, the propt 
miaeion of a budy—in regard to heat as wa 
1 different media, but varies in the rati 
. teiractive indices, su that the whole emitte 
element of a self-luminous body is increase 
when this bey is brought from air into: 
ive index». Ifa glowing body at acon 
as a har of iron, could be immersed int 

« in such a way that the surface wen 
and the eye of the observer im 
5 the body would be seen. brighter 
of 9: 4 than it appeared in air 
ion in air is indeed /ess than the 
as the squares of the 
and 2 
F Tight emitted from an object 
sured by the angle of the 
be measured in any way by 
depends under all circam- 
smi-angle and the refraction 
‘minoux, and is expressed. 
e square of the ‘numerical 



















the quantity of Hight ig 
expression of aperture? 

another point. It wasa 
t the superiority of im- 

Sned to the case of the 





eee. Hier ara alent the aio Bi 
of 170° being in all 


‘The immersion objective, therefore, is able to receive the 


an - 
ee a ela area apertnron ae ime (hare, deceesred 
aboye, the whole question would be of quite subordinate interest, 
Another subject requiring some further elucidation here is the 
ee ee es The 
essence of the idea of ‘aperture’ is relative ny. 
defined, its si; by 


number of (not mere quantity of light photometrically, which 
can be lily varied) which are collected to a given area of the 
and which must have been gathered in by the lens from the 

jugate area of the object. Tf the diameter of the emergent pencil 

is seen to be increased, whilst the amplification of the imageand the 
focal } are unchanged, it is clear that the objective must have 
admit more rays from every element of the object because it has 
collected more to every element of an equally enlarged image, Mani- 
festly we get an accurate measure of what is admitted into an objective 
by being able to estimate what it emits, It is physically impossible 
a system of lenses should emit more light than it has taken in, 

Hence ‘aperture’ means the greater or less capacity of objectives 
for gathy -in rays from luminous objects. 

When he admitted pencil is in the same medium, we «ee the 
additional portions of the solid cone from the radiant, which corre- 
spond to the additional portions of the enlarging opening. But if in 
any other case (e.g. where the medium is different) we see that a 
certain solid cone, A, from a radiant is transmitted through a certain 
opening, a, and that another solid cone of rays, B, cannot be trans- 
mitted through the same opening, a, but requires a wider one, #, 
whilst all other circumstances, except those of the radiant, have 
remained the same, we can only conclude that the pencil B must 
contain rays which are not contained in A, even if the admitted cone 
is not increased in size. For the additional portion (3 —a) of the 
wider opening, 8 conveys rays to the image which are certainly not 
conveyed by the smaller opening a. From the radiant only can this 
surplus come, and the pencil B which requires the additional opening 
must embrace more rays, even if it should not be of greater angle. 

A given objective may, in fact, collect the rays from a radiant in 


38 YISION WITH THE COMPOUND MICROSCOPE 

; ee eau wie tak AeNe 
fifi 2 ound he rst bn i. ys at ter 
for beams.” 


‘The unequal equivalent of equal angles becomes, therefore, a de~ 


mii Ms 


Pro, 40.—Diffrnoted benme in air, Fio. 41.—Diffracted beams in oil, 


monstrated truth—a truth which is capable of experimental proof by- 
bic Coead of a fair tpg honlin a sears 
possessing a dry object-glass of an aperture for 
renee readily do so. Tn this case, a, a fe 18, will represent - 
a. 


170" IN. AIR. Fi % 


Fre, 42, 


the pencil radiating from an object in air, and eapable of being 
taken up by that objective. "This pencil, on its emergence from the» 
back Jens of the combination, will nt a diameter somewhat less 
than twice the focal I of the objective presented in fig. 43. 
But let the object be now placed in Canada balsam and 

covered in the usual way ; the angle of the pencil, by 

the greater refractive power of the medium, will be de- 

monstrably reduced to 80°, as shown in fig. 44. But it 

will be found, on examination of the emergent pencil» 

from the back lens, that this pencil occupies exactly the 

Fro, 43, same diameter (fig. 43) as before. The medium in which 
the object is has not, of course, altered the power of the- 

objective ; and since the diameter of the emergent pencil is the same 
in both cases, the ratio of ‘opening’ to focal length, which is the 
mare. is the same also, Hence it is seen in the simplest way- 

wt diferent angles in media of different refractive indices may 


170" IN AIR 





to. 4k. 





denote equal apertures, and equal angles in different media denote 
different ures. 

‘That ‘immersion’ objectives may have greater apertures than. 
the maximum attainable by a dry objective is capable of equally 
simple proof by accessible experiment. 

f an oil-immersion objective of 122° balsam angle be taken, and 
*0 illuminated that the whole aperture is filled with the incident rays, . 
and if we use first an object mounted in air, we really find that we- 





60 VISION WITH THE COMPOUND MICROSCOPE 7 


demonstrate for himself that immersion lenses not only possess any 
excess of aperture over dry lenses, but that the rays so in excess are 
image-forming. 

The refractive indices of (cedar) oil, water, and air are respeo-{?° 
tively 1-52, 1:33, and 1-0. ‘Angular aperture’ claimed that the +@ 
angles of the admitted pencils to lenses of these three constructions 
expressed equal ‘apertures.’ But this is a fallacy, now so palpable, ! 
but which has exerted an influence so deterrent on the progres * 
of the construction of our higher object-glasses and condensers, f 
that its final disappearance as an unjustified assumption which had = 
crept into the area of theoretical and practical optics, unverified by ; 
facts and devoid of the wedding garment of deduction, is a triumph * 
whisk will make the name of Abbe long and gratefully remem- & 
bered. S 

The principle upon which increase of numerical aperture gives 
increased advantage to an object-glass manifestly needs carefal 
study and elucidation. We have but to refer to the best work done 
by those who have employed the microscope to any scientific purpose 
for the past fifty years to discover that there has been an admission, 
which has steadily strengthened, that by enlargement of aperture an 
increase in the efficiency of the objective, when well made, was 
inevitable. During the last twenty-five years this has been especially 
manifest. To increase the aperture of an objective under the name 
of greater ‘angle’ has been the special aim of the optician and the 
constant and increasing desire of all workers with moderate and 
high powers. 

The true explanation of this is quite independent of any con- 
sideration of apertures in excess of the maximum in air, and indeed 
of the whole question of immersion objectives. The old view that 


all high and excellent results depended on the angle at which the 
light emerged from the object, involving some assumed property of 
a special kind in the obliquity as such, has been most tenaciously 
held ; but it is an a in the problem which has not only never been 





- [Sana 
62 VISION WITH THE COMPOUND MICROSCOPE 


“different obliquities at the object, which is w certain dind of perspec: 
it oa bate ow ther eras anderen 





comparison 
in to aperture in general, so far as it has relation to opening ; 
it CA came ery epee Cork ae of 
light admitted to the system of lenses ; while its failure in to 
delineating power of objectives is everywhere seon and admitted. 
At the same time it is plain that the cause of increased power of 


because their ‘openings’ or ‘apertures’ cannot admit that ‘some- 


thing.” 

What this is becomes explicable by the researches of Abbe, It 
is demonstrated that microscopic vision is sui generis. There is, 
and can be, no comparison between microscopic and macroscopic 
vision, The images of minute objects are not delineated microscopi- 
ly by means of the ordinary laws of refraction ; they are not 
dioptrical results, but depend entirely on the Jaws of diy i 
‘These come within the scope of and demonstrate the undulatory 
theory of light, and involve a characteristic change which material 
particles or fine structural details, in aren to their minuteness, 
effect in transmitted rays of light. The change consists general, 
in the breaking up of an eae ray dato migreas beri wil 
large an; ion within the range of which periodic alterna- 
tions of Ta sod ight occur. sD 

Tf a piece of wire be held in a strong beam of divergent light so 
that its shadow fall upon a white surface, the shadow will not be 

and black, but surrounded by luminous fringes having the 
colours of the spectrum, and the centre, where the black shadow of 
the wire should be, is a luminous line, as if the wire were transparent, 
‘This phenomenon, as is generally known, is due to the inflection of 
the diverging rays on either side of the wire. The inflected rays in 
passing over one edge of the wire meet the rays inflected by the 
other and ‘interfere,’ producing alternate increase and diminu- 
tion of amplitude of oscillation or undulatory intensity, and giving 
rige to coloured fringes if white light is used, and if homogeneous 
light be employed giving origin toalternate bands of light and dark, 
the centre always being luminous, 

Again, if a dise perforated with a very small hole in the contre 
be held in a pencil of diverging light, those undulations which pass 


2 











first of these was held to be a negative it it 
geometrically the constituent parts of the object ; p aiopeecian 
was considered a positive image because it delineates structure, the 
parts of which 9 self-luminous on account of the diffraction 
wi 


was said to be the instrument of what has solong been known as the 
x tier a power of lenses, 

But Dr, Abbe, with the full light of further investigation and 
experience, does not hesitate to modify this explanation. He says : 
*T no longer maintain in principle the distinction between the 
“absorption fea (or direct dioptrical image) and the “diffraction 
image,” nor do I hold that the mic ical image of an object 
— Sone superimposed images of different origin or different 

luction. 

This distinction, which, in fact, I made in my first paper of 1873, 
arose from the limited experimental character of my first researches 
and the want of 4 more exhaustive theoretical consideration at that. 

iod. I was not then able to observe in the microscope the dif- 

ion effect produced by relatively coarse objects because my 
experiments were not made with objectives of sufficiently long focus ; 
henee it appeared that coarse objects (or the outlines of objects 
containing fine structural details) were depicted by the direct]; 
feted a beam of light solely, without the co-operation of diffr 

it. 

a iy views on this subject have undergone important modifica- 
tions. Theoretical soa ora hlens have led me to the conclusion 
that there must always be the same conditions of the delineation as 
long as the objects are depicted by means of transmitted or reflected 
Tight, whether the objects are of coarse or very fine structure. 
Farther experiments with a large microscope, having an objective 
of about twelve inches focal length, have enabled me to actually 
observe the diffraction effect and its influence on the image, viewing 
gratings of not more than forty lines per inch.! 


t 


1 Diffraction effects may be obserred without a microscope; they can be easily 
demonstrated by observing » lamp-fame through a linen pocket handkerchief or @ 
fine ganze wire blind, Thin can be done readily by placing the eye close to the linen 
or 





66 VISION WITH THE COMPOUND MICROSCOPE 


contral it will be clear and uncoloured, but it will be flanked on. 
vither side by a row of coloured spectra of the tame which are fainter 
and more dim as they recede from the centre : fig. 48 illustrates this. 
A similar diaper may also be est ed dust scattered 
glass other objects whose s re contains: 
Teinvte particles, the light auoring m. chardotariatfa red 


Sapa cara 
ing through such objects, that change 
consisting 





sui 

ing in the breaking up of a 

parallel beam of light into # group of 

rays diverging with wide le, and 

Fro. 48. forming a react la rile Ot and 

minima of intensity of light due to ‘difference of phase of vibration, 


In the same way in the microscope the diffraction peneil origin- 
ating from a beam incident upon, for instance, a diatom os 
asa fan of isolated rays, decreasing in intensity as they are 
removed from the direction of the incident beam transmitted through 
the structure, the interference of the primary waves giving a number 
of successive maxima of light with dark interspaces, 

With daylight illumination if a diaphragm opening be interposed 
between the mirror and a plate of ruled lines placed upon the 
the appearance shown in tig. 49 will be observed at the back of the 

objective on removing the eye-piece and 
looking down the tube of the mi 

The central circle is an image of the dia- 
Bhagm opening produced by the direct, 
so-called non-diffracted rays, while those 
on either side are the diffraction images 

0 O00 O J produced by the rays which are bent off 

m the incident pencil. In homogene- 
ous light the central and lateral images 
agree in size and form, but in white light 
the diffracted images are radially drawn 
out with the outer edges red and the 

Fis, 49, inner blue (the reverse of the ordinary 

spectrum), forming, in fact, regular spec- 

tra, the distance separating each of which varies inversely as the 

closeness of the lines, being, for instance, with the same objective 
twice as far apart when the lines are twice as close. 

‘The formation of the microscopical image is explained by the 
fact that the rays collected at the back of the objective, depicting 
there the direct and spectral images of the source of light, reach in 
their further course the plane which is wate to the object, and 
give rise there to an interference phenon n (owing to the connee- 
tions of the undulations), this interference effect giving the ultimate 
image which is observed by the eye-piece, and which therefore 
depends essentially on the number and distribution of the diffracted 
beams which enter the objective. 

Tt would exceed the limits and the object of this handbook to 
attempt a theoretical demonstration of the action of diffraction 
spectra in forming the images of fine structure and striation 80 as 
to afford ‘resolution.’ Those who desire to pursue this part of the 












68 VISION WITH THE COMPOUND MICROSCOPE. 
details, the outline remain’ delineation 
onlin rst me ‘ i Tos asf de mionscope nd sud- 
r Tierra Cs he : EAMES EE leet 
pone polarity 
manipulating the spectra, 





Tf a diaphragm such as that shown in tig. 54 is placed at the back 
of the objective, so as to cut off each alternate one of the upper row 
of tra in fig. 50, that row will obviously become identical with 
the lower one, and if the theory holds good, we should find the image 
of the uy) lines identical with that of the lower. On a it 
the eye-piece we see that it is so; the upper set of lines are foubled 
in number, a new line appem in the centre of the space between 
each of the old (apper) ones, and upper and lower sets having become 
to all appearance identical (fig. nial 

In the same way, if we stop off all but the outer spectra, asin fig. 
56, the lines are apparently again doubled, and are seen asin fig. 57, 


mo) 


Fro, 56, Fro 


A case of apparent creation of structure similar in principle to 
the foregoing, though more striking, is afforded by a network of 
squares, such as fig. 58, having sides parallel to the page, which gives 

‘spectra shown in fig. 59, consisting of vertical rows for the 
horizontal lines and horizontal rows for the vertical ones, But it 
is readily seen that two diagonal rows of spectra exist at right 








7o VISION WITH THE COMPOUND MICROSCOPE 


sm ping gil cnr th wit 
bl 


ina armengement 
ae eae it to bae, another set wt right to 
a third eraser ic. one) “lines 
‘4 0 ‘ef other appearances may Te eel ood ib Si 
\ Sr ta malicest ees 





‘same arrangement of tra with the 

centra}! beam (ax bea) owill form equilateral triangles and gi 

hexagonal markings. by ‘off all but gee (or bd f) we 
shave the in the form of equilateral triangles ; but as 


are now further apart, the sides of the triangles in the two 
cases being as / 3:1, he: ns will be smaller and three times 
as numerous. Their sides will be arranged at a different angle 
to those of the first set. The hexagons may also be entirely 
Sams th bppeer pel at eh apis af iblgeeRicced 
new li il) apy at right angles or obli ineli 
1th ei doe tho herefore, differ) 
yarying the combinations of the spectra, tl fore, different 
rea of Varying size and positions are produced, all of which cannot 
course represent the true structure, 

In practice, indeed, it has been proved that if the position and 
relative intensity of the spectra, as found in any particular case, be 
given, what the resultant image will be can be reached by mathema- 
tical calculations wholly, and with an exactness that- may even to 
some extent transcend the results of previous observation on the 
Pee image of the object whose spectra formed the mathematician’s 


the 
If P. angulatum be illuminated by central light transmitted 
from an achromatic condenser, and examined by means of a homo- 
gencous lens of | aperture, Mr, Stephenson points out! that 
under ordinary conditions it would show, on withdrawing the eye- 
iece and looking down the tube, one bright central light from the 
oe toe six equidistant surrounding diffraction spectra, produced 
hy the lines (‘if, indeed, lines they be ') in the object itself. But let 
a stop made df black paper, which entirely excludes the central beam 
of light, be placed at the back of the objective and close to the pos- 
terior lens ; in the stop let six Gceerinal openings be made through 
which the diffraction spectra may pass, On examining the image we 
find that in lieu of the ordinary hexagonal markings the valve 
appears of a beautiful blue colour on a black ground, and covered 
with circular spots, clearly defined, and admitting of the use of deep 
eyes 

iis is proclenl what we learn from Abbe that the diffraction 
theory involves. Tn support of this, thé philosophical faculty of the 
University of Jena had proposed as a question to the mathematical 
students the effect ection in the microscope by these interference 

phenomena. One problem was that of the appeafance produced bt 

six equidistant spectra in a circle ; they correspond precisely witl 
the spectra of P. angulatum, as uccessible to us with our present 
numerical aperture ; and the diagram of the diffraction image, de- 

1 Journ, RALS, vol. 1. 1878, p. 186, 





THE COMPOUND MICROSCOPE 





“over as they are capable of being demaw 
uathematician. 

scn:ptiens and with all other considem 
ageneous objectives of greatest ya 
alt us the real structure of the 

ss Wy learn that dieimilar structores wil 
~. when the difference of theid 
versely similar structures 
sditfractive images are 

rs point for point to the 
a safe inference to be 
: hut the diffraction or 
and in no direct relation 
necessity conformable to 
inute structural details are 
iy or divptrically, and can- 
“rng, Wat only as signs of 
» jarticles composing 

= inferred from the image 
zoe in the object of such 
spevitie diffraction pheno- 



































imber of diffracted raps 
ximilarity between tht 





nds always on the sd- 

on of the whole of 
2 tos yetent to emit. 

: ad corpuscles or 

to that of equal 

cround, and theory 

4 iform. dissipt, 

here, provided the 








PatAt 
necdum s€ muct shorn waveleagh 
not thee commmemmnose: no ole 
> emer: wit mary bes apes 
PUL Tet ¢ umaniane or strictly silat 





76. VISION WITH THE COMPOUND MICROSCOPE 


ii lutely a 6 obj 
‘The rule given by Professor Abbe el ing the greatest 
Borie ce never which can be resolved by ol light will 
be Beer eee reet ee earn) ioe aiee eee 
the number of in an inch multiplied by the numerical 


‘To those who have studied this subject it will be seon that the 
‘numerical aperture’ here takes the place of what was formerly the 
‘sino of half the angle of aperture’; and it has the effect of givin; 
the jon a broader generality. By using the ‘sine of hal 
Serra ne peace is only true with the addition 
number of undulations be calculated from the wave-length 
within the special medium to which the angle of aperture relates. 

Tn the numerical aperture instead of the sine of the 
angle, the latter (the sine) is increased in the proportion of 1: n 
(n standing for the index of the medium), and that has the same 
effect as increasing the other factor the number of undulations. 

What the coloar employed shonld be is only ee of individual 
determination, since the capacity for appreciating light varies witl 
different individuals. eae as 

Tf, for instance, we take “43 in the solar spectrum as being 
sufficiently luminous for vision, we find the maximum—so far as 
wee is concerned—to be 118,000 to the inch (the object, in this 
ease, being in air) ; but as the non-luminous chemical rays remain 
in the after the departure of the visible rum, bet pare 
graphic image of lines much closer together might be produ 





Fio, 66, 


This important subject can scarcely be considered complete, ever 
in outline, without a brief consideration, in their combined relations, 
of apertures in excess of 180° in air and the special function these 
apertures 

1, Suppose any object composed of minute elements in regular 
arrangement, such as a diatom valve ; and, to confine the considera- 
tion to the most simple case, suppose it illuminated by « narrow 


s VISION WITH THE COMPCUND MICROSCOPE 


would be emitted in air under an angle of 66°5°, but in balsam the 
third would attain the same obliquity. Whilst now the dry objective 
of 133° air-angle cannot admit more than the two firat diffract 

beams on each side of the axis, the immersion of 193° balsam-angle 


s 


Be 
z 
i 
z 
i 


Tt follows, therefore, that a balsam-angle of 75° denotes the same 


as the w air-angle of 133°, and a balsam-angle of 133° 
Be pasate ees oo Ic at banee aac 


general two apertures of different objectives must be 
if the sines of the semi: are in the inverse ratio of the 
the medium to which they relate—or, which is the 
juct of the refractive index multiplied by sine 
angular semi-aperture (n sin u) yields the same value for both, 
they ate of the sae numeral pert 
Suppose the same object to be ol tee by ey Lea 
given air-angle, at first in air uncovered, then in 
protected by a cover-glass, The firat ease would be represented by 


i 
5 
i 
& 


a 
i 
a 


& 
e 








fig, 66, and the second by fig. 68. As we have seen, the group of 
diffracted beams from the object in balsam is contracted in com- 
parison to that in air in the ratio of the refractive index, But 


+ ‘The following are the actiial angles ropresented in the diagrams, vie: 
(Strie = 22 p, wave-length A = °55 4, medium air m = 1.) 
me sks ag : 
By = 0° 0° 
Ss = 48° 30" 
5p = 00° 0, 
(Steim = 22 4, wave-length d = 5 i. medium balsam ” = 1°.) 
= oF 


8; = 19° a 


80. VISION WITH TIE COMPOUND MICROSCOPE 


ir 
structure that can be disclosed with: 
into an oil immersion, and es) an ‘ay ‘twin of 
ce Saha of the all-revealing beams by the 
0 
bs Moat 3 splendid results have been attained both in 
dow and “to high por wo works but all the latter is being advanced upon 
of greater aperture in a striking manner. 
twenty years we have been i achat our best English microscope 
ae to en! the ‘angle’ and Scperng 
eee a to a ,\-inch eee We have seen 
aeagtie Fyito.\water ininiersion, eid from this'tol ol from 
inch, a y-inch, and a qgy-inch of N.A. 0-95 each, and re- 
Bective te water immersions of N.A. 1-04 and then renee 
iinmersions’ or homogeneous lenses of N,A. 1°38 for the 
and ,-inch respectively, and eeey by a bree wil RY 
of 1:50; and from that we have progressed to the apochromatic 
objectives with compensating eye-pieces, 

Now oy Cnet ee which es earlier work pk es the 
present editor a1 is colleague, Dr, > Drysdale, wus ¢! j—to 
which allusion is made only as being “the instance with which we 
have most practical fumilinrity—are still in our possession ; what 
was revealed by them fifteen, twelve, or ten yenrs ago we can 
exactly t to-day ; and in the enn features of the workin 
the characteristics of the life histories of the breed 

organisms, minute as they are, revision with objectives of 
and other lenses of the best English and German makers, reveals no. 
positive error, even in the minutest of the details then discovered and 
delineated. But the later lenses of great aperture and benutifal 
corrections have opened up structure rutely invisible before. 

Thus, for ean: ‘a minute oval organisin from the qyyath ~ 
the gylyth of an inch in long diameter was known to 
distinct nucleus ; the long diameter of this was from the ,\,th *6 
the th of the diameter of the whole body of the organism. In the 
observations of ten to fifteen years since the cyclic changes of the 
entire organism were clearly visible and constantly observed ; but 
of the nweleus nothing could be made out save that it appeared to 
share the changes in self-division and genetic repre initiated 
by the organism as a whole. But by lenses of N.A. 1°50 and the 
finest apochromatic objectives of Zeiss, especially a most beautifully 
corrected $3 mm. and 2 mm., structure of a remarkable kind has 
been demonstrated in the nucleus, and it has been shown that the 
initiation of the great cyclic changes takes place in the nucleus, and 
ix then shared in by the organism as a whole, In short, we have 
discovered as much concerning the ‘inaccessible’ nucleus—which 
may be not more than, say, a twelfth of the long diameter of the 
whole organism—by means of lower powers, but greater apertures, a8 
we were able to find concerning the complete body of the saprophyte 
with dry objectives. 

But in spite of these facts there is a certain class of even high 
power work in biology from which the dry lens can never be dis+ 


Te 


fa 
E 


the 
circumstances on which what has been called poneteasicas! 
ives is dependent will be shortly considered ;* it may 

that theory and experience alike show that ‘penetration ’ 
with increasing aperture under one and the same ampli~ 


EB 


iF 


af 
1M 
i: 
3 
u 
$3 
z: 
i 
LE 


"ws possible. This is always the ease where the 
solid forms—as the infusoria, for exam ‘is Ne 
pialin o ieee anes Ashpalt eeactio dy T the 

greater part of all morphological work is of kind ; here, then, 
in the words of Abbe, ‘a economy of aperture is of equal 
importance with economy of power.’* A 

Whenever the depth of the object or objects under observation is 
notvery restricted, and for the purposes of observation we require depth 
ieee ical peticterata porrace cacsh-berpeed extant ter 
aperture should therefore be used than is required for the ‘ive- 
ness of these powers—an excess in such a case is a real i! 

‘Moreover, in biological work—constant application of the instra- 
ment to varied objects—lenses of moderate aperture and suitable 
facilitate certainty of action and conserve labour. Tnerease 
of aperture involves « diminished working distance in the objective, 
and it is inseparable from a rapid increase of sensibility of the 
objectives for slight deviations from the conditions of perfect cor- 
rection. If it be not necessary to encounter the possible difficulties 
these things involve, to do so is to lose valuable moments. These 
difficulties, of course, are diminished by the use of homogeneous, and 
especially apochromatic objectives, but even with these they are 
not, in practice, done away where the best results are sought, 

‘Employ the full aperture suitable to the power used. This ix the 
practical maxim taught in effect by the Abbe theory of microscopic 
vision. 

Tt has been suggested that all objectives be made of relatively 
wide apertures, and that they be ‘stopped down’ by diaphragms 
when work of ‘lower apertures’ has to be done. But this is 


i 


> 
E 


; 


1A mioron is w= yey mm. Vide Journ. RAS. 1888, pp. 602 and 626; and 
Nature, vol. xxxviti. pp. 221, 944. ? Seo p. Bu. 
ibe's explanation of the reason of the non-stereoseopic perception of these is 


Al 
ven {x00 pp. 08 et seq). 
5 She ‘Halation of Apertore to Power,’ Journ. IMS. series i. volt. p. 80k, 





1—NUMERICAL APERTURE TABLE. 





BpSSSRESSCTCRRASSEREEES 








2310 
2280 


RRES2SE222S 235902225288 


Spe Bae aas 












193,087 


57,800 | 191,767 


BSS 

















L=mainw) (w=100) (n=133) En 











ae 
Bh 
ae aoe 
[atsatst setet t 
§-52-2- ie é 
4, oA AR sfiaa'- 
e338 3. 2 & 
Ba § qe 4 
3 - 2: 7 
1 ne ee 
Beg y=. 244. Fy 
Sge 532 “exe & 
pages acta ae 
HEE iiish 3 
eee 2853 
grees Paria 4 
jae «& Ss & = 














85 


N.A, TABLE Ere, 


S2S25522 


3 





2 





rs 
‘ 
i= 








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LA 











Petb ere eR b ys 








VISION WITH THE COMPOUND MICROSCOPE 





3233255225 














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wog'tot | go9'sn 
#9 we're 
aebOT | say'on 
wor'sol | ReL'9s 





youy tte 04 
SourT my aamog Suyaqonoy yo aprayy | 





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ith 069 








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= ‘sompode [worouME Z}9y} CIO BET =» HT eg. su “UoAaMOY ‘axe SoMOde sonauw JOT 
OBE SET oT = 0T 

<i ae 48h si i sMoy]oy se Ma}\ oaq20de 
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“oan uyhumluooon 242 burrouzenye atunagy 














000-08 200: | og’ | oas'y | rast [op of |e uy jr oo 
2499-91) F00: | ozo's | ole'o | gata” | 126 oF | or og | iGo 59 
0o-%1) 900- | ootor | Gee's | ere [is o9 | 49 69 \it 26 
000-01) OTO- | OLE | OsFor | THO'S | ¥8 of | (98 08 |,6e IT 
sens 10- | ors'or | org'er |. ono'tt | 06 | ‘ae cOL |e 2ST 
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999) GeO. | o9s'ae | TIS'ST | FOeZT | .98 oft] ‘FE O91 [FF 08 
000-9 | oF0- | ooFGs | Tos‘ | sector | 2 ooT| i8T oLt\ ace 
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2986 | HE | Tesvay | teoles 
aang | Per | aera | Ay 


























w VisioN WITH THE COMPOUND MICROSCOPE 


\ pramssive, and with high powers a rapidly increasing, 
naplitivation of the depth of the thrve-dimensional image. 
transverse section of an abject is magnified 100 times in bread! 






























istance between the planes of parts lying une behind the 
magnified 10.000 times at the corresponding parts on the axis 
the obre in air, 7500 times when it is in water, and 6600 
when it balsam. 


«Xo-wive distortion in the case uf high amplificationsis 
> complete a hindrance to correct: appreciatis 
microscopical image as at first appears, 
cur is not a matter uf sensation only 5 it 
and, therefore, the peculiarity of 
great the ane ation, would not 
» long as salient. 
7 image were found. 
such, must be simultaneously i 






















£ . . weecianble depth can convey no peace, 
Ra av usiuns possessed by the object. 
so. ct isproportional amplitication of the depth-dimensix 





seen of optical instruments the visual space of 
oe sve te and more in depth as the aioplification ine 
+ a 4GY approxinmtes toa hire horizontal seetion of 





sewers which at one adja 





a certain depth 





wes he vely depicted “ith perfect. sharpness 
J oan Is li itself by conscioas 
+ wvennuodation, obtains vi 
: . This depth siation, which pls 
% i 5 sion, is wh 





90 VISION WITH THE COMPOUND MICROSCOPE 


‘The following table shows the total depth of vision from ten to 
3,000 times :— 








os EE of 
sce areata EES ESE 
es nara ® Sacei | ‘ 
10 | aon | ses oo | ats | sie 
1 
so | es | om oot oak ar 
ove 0007s ret _ 
wo es | | ‘ | re 
900 oases | oooet | oooir | reg 
| 
1000 | 035 | commen covers | 00a | ar 
3000 | Goss 0100002 oes | 00025 


iS 
= 


Tt has been pointed out by Abbe that this over-amplification of 
depth-dimension, though it limits the direct a) jation of solid 
forms, yet is of great value in extending the indirect recognition of 
space relations. When with increase of magnifying power the depth 
of the image becomes more and more flattened, the im: of different 
planes stand out from each other more ly in the same ratio, 
and in the same degree are clearer and more distinct. With an 
increase of amplification the microscope acquires increasingly the 
property of an optical microtome, which presents to the observer's 
eye sections of a fineness and sharpness which would be impossible 
to # mechanical section. It enables the observer by a series of 
adjustments for consecutive planes, to construe the solid forms of 
the smallest natural objects with the same certainty as he is 
accustomed to see with the naked eye the objects with which it ix 
concerned, This is a large advantage in the genoral scientific use 
of the instrument ; a greater gain, in fact, than could be expected 
from the application of stereoscopic observation. 

Stereoscopic Binocular Vision,—This subject has been elaborately 
considered and partially expounded and demonstrated by Professor 
Abbe ; his exposition differs in some important particulars from 
that of the original author of this book, but in its present incomplete 
form it appears to the editor to be the wiser way to allow Dr. Cur- 
penter’s treatment of the subject to stand, and to place below it as 
complete a digest of Professor Abbe’s theory and explanation of the 
same subject as the data before us will admit. 

The admirable invention of the stereoscope by Professor Wheat- 
stone has led to a general appreciation of the value of the conjoint 
use of both eyes in conveying to the mind a notion of the solid forms 
of objects, such as the use of either eye singly does not generate with 
the like certainty or effectiveness ; and after several attempts, 
which were attended with various degrens of guecess, the principle of 





92 VISION WITH THE COMPOUND, MICROSCOPE 


small square in the centre, but the four sides sloping equally to- 
wards it. 

Thus we see that by simply crosving the pictures in the stereo- 
scope, #0 a8 to bring before each eye the picture taken for the other, 
a ‘conversion of relief’ is produced in the resulting solid image, 
the projecting parts being made to recede and the receding parts 

cht into relief. In like manner, when several objects are com- 
bined in the same crossed pictures, their apparent relative distances 
are reversed, the remoter being brought nearer and the nearer 
cartied backwards ; so that (for example) a stereoscopic photograph 





Fro, 69, 

representing a man standing in front of a mass of ice shall, by the 
crossing of the pictures, make the figure appear asif imbedded in the 
ice. A like conversion of relief may also be made in the case of 
actual solid objects by the use of the psewdoscope, an instrument 
dlevised by Professor Wheatstone, which has the effect of reversing 
the perspective projections of objects seen through it by the two 
eyes respectively ; so that the interior of a basin or jelly-mould is 
made to appear as a projecting solid, whilst the exterior is made to 
appear hollow. Hence it is now customary to speak of stereoscopic 
vision as that in which the conception of the true natural relief of an 
object is called up in the mind by the normal combination of the 
two perspective projections formed of it by the right and left eyes 
respectively ; whilst by pseucoscopie vision we mean. that ‘conver- 
sion of relief’ which is produced by the combination of two reversed 
perspective projections, whether these be obtained directly from the 
object (as by the pseudoscope) or from ‘crossed ' pictures (as in the 
stereoscope). It is by no means every solid object, however, or eves 
pair of stereoscopic pictures which can become the subject of this 
conversion. The degree of facility with which the ‘ converted ’ form 
can be apprehended by the mind appears to have great influence on 
the readiness with which the change is produced. And while there 
are some objects—the interior of a plaster mask of a face, for ex- 
ample—which can always be ‘converted ' (or turned inside out) at 

















——y 


“unaltered, whether viewed by an axial or an oblique pencil ; there is 

foreshortening, there i: lateral di of the images 

msecuti “Bat. contends that, whilst the manner in 
are formed 





i 
‘ 
i 
i 
: 
| 


: 
| 
E 
1) 
H 
: 
é 


Professor Abbe demonstrates ' that in an aplanatic system pencils 
of different obliquities yield identical images of every plane object, 
or of a single layer of a solid object, This is true however lange the 
aperture may be, i 

This carries with it, as we have said, a total absence of perspec- 
tive and an essential geometrical difference between vision with the 
binocular microscope and vision with the unaided eye. 

An object, not quite flat, asa curved diatom, when observed with 
an objective of wide aperture will present points of great indistinet- 
ness. Poi aa bee by mieneimmpieotel $0 ariae froma the Ssteeiatees 
that there was a dissimilarity the images formed by the 
axial and oblique pencils ; but this is not so. It is wholly explie- 
able by the fact that the depth of the object is too great for the 
small depth of vision attendant upon a large aperture. 

Tt will be seen, that so long as the th of the object is 
within the limits of the depth of vision, corresponding to the aperture 
and amplification in use, we obtain a distinct parallel projection of 
all the successive layers in one common plane perpendicular to the 
axis of the microscope— und plan, as it were, of the object. 
Manifestly, then, since depth of vision decreases with i 
ay good delineation with these must be confined to thinner 

jects than ean be successfully employed with objectives of narrow 


apertures, 

Stereoscopic vision with the microscope, therefore, is due solely 
to difference of projection exhibited by the different parallactio dis 
placements of the images of successive layers on the common ground 
plane and to the perception of depth, not to the delineation of the 
plane layers themselves. For, if there were dissimilar images per- 


1 Journ. HAS. serien ii, vol iv, pp. 21-24, 


aad 


Pa VISION WITH THE COMPOUND MICROSCOPE 











of 


| 
; 


ey 


98 VISION WITH ‘TIE COMPOUND MICROSCOPE 

mediately after its publication, and Mr. Wenham in London and 

BEML Necket, of Paris, soon suggested and devised. variety” of? 
a ‘Binocular.—One of these (not now, we have reason to~ 


eve, advocated or employed by its inventor) that d 
Sslaee euciucote eninils hethoal Dig te He Ld 


i 
e 


ah that form the right half of the cone, impinging very ely or 
Cieearenial fos cb ries entns tobe reteeeee: c 

its left side perpendicularly to its surface, and therefore undergoing: 
no refraction ; whilst the rays a’ b', forming the left half of the cone, 
are reflected in like manner towards the right. Each of these 


two halves a} and a’ b’ of the original pencil are completely rated) 
from each other, the former bein; relied into mt Tefthand, body 
‘of the microscope (fig. 73), and the latter into its right-hand body. 
‘These two bodies are lel ; and, by means of an adjusting screw" 
at their base, which alters the distance between the central and the 
lateral prisms, they can be separated from or approximated towards: 
each other, so that the difference between their axes can be brought 
into exact coincidence with the distance between the axes of the 
eyes of the individual observer. This instrument gives true ‘stereo~ 
scopic’ projection to the conjoint image formed by the mental fusion 
‘of the two distinct pictures, and with low powers’ of moderate: 
angular aperture its performance is highly satisfactory. There are, 
however, certain drawbacks to its general utility. First, every ray 
of each pencil suffers two reflexions, and has to pass through fowr 
surfaces: this necessarily involves a considerable loss of light, with a. 
further liability to the impairment of the image by the smallest 
want of exactness in the form of either of the prisms. Secondly, the 
mechanical arrangements requisite for varying the distance of the 
bodies involve an additional hability to derangement in the adjust- 
ment of the prisms. Thirdly, the instrument can only be used for its: 
own special purpose; so that the observer must also be provided 
with an ordinary single-bodied microscope for the examination of 
objects unsuited to the powers of his binocular, Fourthly, the paral- 
jelism of the bodies involves parallelism of the axes of the observer's 
eyes, the maintenance of which for any length of time is fatiguing. 
Wenham’s Stereoscopic Binocular.—All these objections are 
overcome in the admirable arrangement devised by the ingenuity of 
Mr. Wenham, in whose binocular the cone of rays proceeding up- 
wards from the objective is divided by the interposition of « prism 
of the peculiar form shown in fig. 74, so placed in the tube which 
carries the objective (figs. 75, 76, a), as only to interrupt one half, 
ae, of the cone, the other half, «6, going on continuously to the eye- 
piece of the principal or right-hand body, R, in the axis of which the 
objective is placed. The interrupted half of the cone (figs. 74, 75, a). 





WENHAMS BINOCTIAR PRISM 99 


on its entrance into the prism, is scarcely subjected to any refraction, 
since its axial ray is perpendicular to the surface it meets; but 
within the prism it is subjected to two reflexions at b and ¢, which 
send it forth again obliquely in the line 
d towards the eye-piece of the secondary 
or left-hand body (tig. 75, L); and since 
at its emergence its axial ray is again 
perpendicular to the surface of the glass, 
it suffers no more. refraction on passing 
out of the prism than on entering it. By 
this arrangement the image received by 
the right eye is formed by the rays which 
have passed through the /q/? half of the 
objective, and have come on without any 
interruption whatever; whilst the image 
received by the /</t eye is formed by the 
ae which have passed through the right 
of the objective, and have been sub- — pyy. 74 —Werlwzn's prin. 

jected to two reflexions within the prism, 

Passing through only tio surfaces of glass. The adjustment for the 
variation of distance between the axes of the eyes in different in- 
dividuals is made by drawing out or pushing in the eye-pieces, which 








Wenkaun's stermoscup!e binocula 





moved consentaneously by means of « milled-head, as shown in 
76. Now, although it may be objected to Mr, Wenham’s method 
»bliquely 





(1) that, os the rays which pass throug! the prism and ar 
reflected into the secondary body traverse a longer dist 








=F 


100 VISION WITH THE COMPOUND MICROSCOPE 


those which ‘on uninterray into the principal body, the 
icture formed by them will Tomes Target hau ‘that whieh 
is formed by the other set; and (2) that the picture formed by the 
rays which have been subjected to the action of the prism must be 
inferior in distinctness to that formed by the uninterrupted half of 
the cone of riys ; these objections are found to have no practical 
weight, For it is well known to those who have experimented 
upon the phenomena of stereoscopic vision (1) that a slight differ- 
ence in the size of the two pictures is no bar to their perfect com- 
bination ; and (2) that if one of the pictures be good, the fall effect 
of relief is given to the image, even though the other picture be 
faint and imperfect, rareidea® that the outlines of the latter are 
pi haan ie inet to represent its perspective projection. Hence 
if, inst of the two equally hal/-good pictures which are obtainable 
ly MM. Nachet’s original construction, we had in Mr. Wenham’s 
one good and one indifferent picture, the latter would be decidedly 
preferable. But, in point of fact, the deterioration of the second 
picture in Mr, Wenham’s arrangement is 
Jess considerable than that of both pictures 
in the original arrangement of MM. Nachet; 
so that the optical performance of the Wen- 
am binocular is in every way superior, Tt 
has, in addition, these further advantages 
over the preceding : First, the greater com- 
fort in using it (especially for some length 
of time together), which results from the 
convergence of the axes of the eyes nt their 
usual angle for moderately near objects; 
secondly, that this binocular arrangement 
does not necessitate a special instrument, 
but may be applied toany microscope which 
is capable of carrying the weight of the 
secondary body, the prism being so fixed in 
u movable frame that it may in a moment 
he taken out of the tube or replaced there- 
Fig, 77-—Riddell's binocular jn, so that when it has been removed the 
Suphnanet YM principal body acts in every respect ms nm 
ordinary microscope, the entire cone of rays 

passing uninterraptedly into it; and thirdly, that the simplicity 

its construction renders its derangement almost iinpossible. 

Stephenson's Binocular.—A new form of stereoscopic binocular 
n introduced by Mr. Stephenson,? which has certain dis- 
¢ fentures, and at the time Mr. Stephenson devised it he was 
entirely unaware that any part of the method he employed had been 
used by another, He had, however, independently conceived Rid- 
dell’s device for dividing the beam as a part of his very ingenious 
instrument. This he discovered and acknowledged about three 





























1 Phe Anthor cannot allow this opportunity to pass without expressing his sense 
of the Hberality with which Mr. Wenham freely presented to the pmblic this im- 
portant invention, by which, there can be no doubt, he might have largely pro- 
Sitod if he had chosen to retain the exclusive right to it, 

# Monthly Mécroscoptcat Journal, vol. iv. (1870), p. 61, and vol. vil, (1872), p. 107. 








STEPHENSONS BINOCULAR lor 


os after the full description and completion of his binocular.! 
cone of rays ing upwards from the object-glass meets a pair 
of prisms (A A, fig. 77) fixed in the tube of the microscope imme- 
above the posterior combination of the objective, so as to catch 
the light-rays on their emergence from it; these it divides into two 
halves and behaves as <dlescribed in the Riddell prisms, which, in fact, 
aber, are. As the cone of rays is equally divided by the two prisms, 
and its two halves are similarly acted on, the two pictures are equally 
illuminated, and of the same size ; while the close approximation of 
the prisms to the back lens of the objective enables even high powers 
to be used with rey. little loss of light or of definition, provided 
that the angles and surfaces of the prisms are 
worked with exactness ; and as the two bodies 
can be made to converge at a smaller angle than 
in the Wenham arrangement, the observer looks 
through them with more comfort. But Mr, Ste- 
phenson's ingenious arrangement is liable to the 
grat drawback of not being convertible (like Mr, 
enham’s) into an ordinary monocular by the 
withdrawal of 4 prism, so that the use of this form 
of it will be probably restrictod to those who desire 
to work with binocular when employing high eal 1h 
powers In order to avoid slight errors arising 
the impinging of the central ray of the cone, at its emergence 
from the objective, against the double edge of the prism-combination, 
Mr. Stephenson has devised a special form of sub-staye condenser 
{also made by Mr. Browning), which causes the illuminating mys to 
issue from the object in two 
separate pencils, which will 
strike the surfaces of the two 
isms, ‘This consists of two 
cylindrical lenses.A and 
B, fig. 78, whose focal lengths 
are as 23 to 1, having their 
curved faces opposed to euch 
other, as shown in section at 
me larger and less convex 
i with its plane side 
aenearte, 80 as to receive 
light from the mirror, or (which 
ie ble) direct from a 
lamp. Under this combination Fra, 70. 
slides a movable stop, with two circular openings, as shown in fig. 
79. The lamp being placed in front of the instrument, the two 
apertures admit similar pencils of light from it, so that each eye 
receives a completely equal illumination, anc no confusion can occur 
from the impinging of the rays on the Jower edges of the prisms, 
With this arrangement the Podura markings are shown as figured 
by the late Richard Beck, while the curvatures of the scale come 
ont with the distinctness peculiar to binocular vision, 
4 Monthly Microscopical Journal, vol. x. p. 41. 











102 VISION WITH THE COMPOUND MICROSCOPE. 


But one of the greatest advantages attendant on Mr. Si = 
son's construction is its capability of being combined with an 
erecting arrangement, which renders it applicable to purposes for 
which the Wenham binocular cannot be conveniently used. By 
the interposition of a plane silvered mirror, or (still better) of a 
reflecting prisin (fig. 80), above the tube containing the binocular 
prisms, each half of the cone of rays is 
so deflected that its image is reversed 
vertically, the mys entering the prism 
through the surface CB, being reflected 
by the surfuce AB, so as to out 
again by the surface AC in the direc- 
tion of the dotted lines, Thus the right 
cones aredirected respec- 
into the right and the left bodies, 
which are inclined at a convenient 
angle, as shown in fig. 81; so that— 
the stage being horizontal —the instru- 
ment becomes a most useful compound 
(lissecting microscope, and as thus ar- 
ranged by Swift, with well adjusted rests 
for the hands, has but few equals for the 
purposes of minute dissections and delicate mounting operations ; 
indeed, the value of the erecting binocular consists in its applie- 
ability to the picking out of very minute objects, such as Diatoms, 

Polycystina, or Foraminifera, 
and to the prosecution of 
minute dissections, especially 
when these have to be carried on 
in fluid. No one who has only 
thus worked monocularly can 
appreciate the guidance derivable 
from binocu/ar vision when once 
the habit of working with it has 
been formed. 

Tolles' Binocular Eye-piece.— 
An ingenious eye-piece has been 
constructed by Mr. Tolles (Boston, 
U.S.A.), which, fitted into the 
body of « monocular microscope, 
converts it into an erecting stereo- 
scopic binocular, This conversion 
is effected by the interposition 
‘of a wystem of prisms similar to that originally devised by MM. 
Nachet, but made on a larger scale, between an ‘erector’ (re- 
sembling that used in the eye-piece of a day-telescope) and a pair 
of ordinary Huyghenian eye-pieces, the central or dividing prism 
being placed at or near the plane of the secondary image formed by 
the erector, while the two eye-pieces are placed immediately above 
th » lateral prisins, and the combination thus making that 
division in the. pencils forming the secondary image which in the 











Fio, 40. —Stephenson's erecting 
prism. 








Stophensem's erecting 
binocular. 
















oe ct eal one ’ . and the other 
Miaiesea ier taech oe ae clas Gita need are . ‘The rays. 
reflected at the angle shown in figure pass ‘the second 


an 

cted into the eye-piece B’ ut an angle of 90° by the: 
surface of the right-angled equilateral prism 6’, the 
tote ie ofthe rahe ter ry the 
Adjustment for different distances between the eyes is effected 
by the sorew D, which moves Shs feye nies) 8’, together with the- 
prism 4, in a parallel direction. tubes of the eye-pieces can 

drawn out if greater separation is required. 
The eye-pieces have the usual two lenses, but are of ‘ial con- 
in order to equalise the length of the direct axis and the: 


eye: 

real image of the objective opening formed above the eye-pieces at- 
the so-called ‘ aye pont B or 8, which represents the common 
cross-section of all the pencils emerging from the eye-piece. A cap: 
with a semicircular diaphragm is fitted to the eye-piece (shown in 
the figure over f’), the straight edge of which is exactly in the 
optic axis of the eye- , and can be raised or lowered by screwing 
80 a8 to obtain « uniform bisection of the cones of rays every 
point of the field. 

The height of the diaphragm is regulated once for all for the- 
same length of the microscope-tube by finding the position for which 
the aperture-image (which on withdrawing the eye from the eye- 
piece 1s visible as a bright cirele above it) shows no parallax against 
the straight edge of the diaphragm, ie. so that on moving the eye: 
laterally the image always appears to adhere to the edge. 

Tn addition to the above caps with diaphragms the instrument 
is supplied with ordinary caps with circular apertures, as in B. 
‘They taper slightly and simply slide into the eye-piece, so that 
they can be readily changed. ‘The special feature of the instrument. 
is Ist, that it is capable of being used with the highest powers; and 
2ndly, that it ix not necessary to cover up half of each of the eye-piece 
tubes, thus losing half the total amount of light. It is sufficient if’ 
one only (the lateral one) is half obscured, leaving the other free, 
As the normal division of light between the two tubes is two-thirds 
(in the axial) and one-third (in the lateral), the total loss of light is 
reduced to one-sixth, 

The field of view in the axial eye-piece in this arrangement in 
any cwse necessarily appears brighter than that of the lateral one 
seen with the same eye, and in regard to this Dr. Abbe re- 
marks that the difference between the brightness of the two fields. 
in binocular observation ‘is not only no defect, but, on the contrary, 








i ail | 


106 ‘VISION WITH THE COMPOUND MICROSCOPE 


Seeiter eal Emecesenily decreased: iN peasreeehpry ae oe 
ition. wl i low of soli jon are 
ee eee 
light, it on that under these pees the aces ae Boe 
two images is founded, not on whole aperture-angle ol 
fasts, ‘but on the much smallor angle of the incident and directly 
transmitted pencils, which only allow of relatively small differences 
‘of inclination of the image-forming rays to the preparation. It is 
evident, however, that when objectives 


of short focus and lingly large 
angle are used, a consi 
differentiation of the two i with re- 


nen to parallax can be luced if, in 
place of one axial illuminating peas two 
pencils ave used oppositely inclined to the 
axis in oe ne qr thee aes of jes 
im is produ one 

‘This Kind of double iiiumafoation, thou 

if, cannot Pa bee peels ers i 
mirror, can be ensil a 

aes with the condenser ederhen with iam 
openings (fig. 83), placed in the diaphragm stage under the con- 
denser. We then have it in our power to use, at pleasure, pencils 
of narrower or wider aperture and of greater or less inclination 
towards the axis by making the openings of different width and 
«lifferent distance apart. 

With diaphragms of this form (which can easily be made out of 
eard-board) the larger aperture angles of high-power objectives may 
be made use of to intensify the stereoscopic effect without employing 
wide pencils, which are prejudicial both as diminishing the clearness 
of the image and the focal depth. 

Of course with this method of illumination both eye-pieces must 
be half covered in order that one image may receive light only from 

one of the two illuminating cones, and the other only 

from the other. The division of light in both the aperture- 

ci images will then be as shown in fig. 84; and it is evident 

that in this case the brightness of the image for both eyes 

Fw.as, together is exactly the same as would be given by one 
of the two cones alone without any covering. 

The method of illumination here referred to—which was origin- 
ally recommended by Mr. Stephenson for his binocular mic 
has, in fact, proved itself to be by far the best when it is a question 
of using higher powers than about 300 times. It necessarily requires 
vernal corrected and properly adjusted objectives if the sharpness 
of image is not to suffer; but if these conditions are satisfied it 
yields most striking stereoscopic effects, even with objectives of 
2 mm. and less focal length, provided the preparation under obser- 
vation presents within « small depth a sufhciently characteristic 
structure, 

Non-Stereoscopic Binoculars.—The great comfort which is ex- 
perienced by the microscopist from the conjoint use of both eyes hus 





108, VISION WITH THE COMPOUND MICROSCOPE 


sh ess Ritore ani ae nee 
of CAS ject, in which we have endeayoured, with as much clear- 
ness as we could command, to 
enable the 


pate eapie ve ticegeye 
serve the higher interests of 


cia nd the wants or de- 
sires of cake adveapelicken= 


if we endeavour 
‘bee ire irra 
or 
TTT ae a general” 
outline and then an application 
uf the famous dioptric investiga- 
tions of Gauss, an eminent Ger- 
min mathematician, who amongst 
many other brilliant pase in 
spelled mathematics expounded 
laws of the vefraction of light 
in the case of « co-aial system of 
. spherical surfaces, having media 
of various refractive indices lying 
between them. 

Although the assumptions 
upon which the formule of Gauss 
rest are not coincident with the 
conditions presented by the lens- 
combinations which are employed 
in the construction of modern 
objectives of great aperture, the 
results, nevertheless, furnish an 
admirable presentation of the 
path of the rays and the positions 
of cardinal points, even in the 
microscope as we know und use it. 

We remember that the miero- 
ma is largely used in England 

America by men who can 
only employ it in their more. or- 
less brief recessions from. profes- 
sional and commercial pursuits, 
but who often employ it with en- 
thusiasm and intelligent purpose. 
y ° ‘Much scientific work may be done- 

by such men, and it will promote 
the accomplishment of this, in our judgment, if the frequently ex~ 
pressed desire be met which will enable such students to understand! 


1 This figure is greatly exaggerated for the sake of clearness 


Ad 


Fe. 








DIOPTRIC INVESTIGATION BY GAUSS Too 


in a general but thoroughly intelligent manner the principles in- 
volved in the employment of systems of lenses. 

Many such either have scanty knowledge of algebra, or in the 
continuous pressure of other claims have lost much that they once 

We believe that in these cases the following exposition 
.of the dioptric system of Gauss, with a following example worked 
out in full and with every step made clear, will be of real and 
practical value. " Without some intelligible understanding of the 
ultimate principles of the microscope no results of the highest order 
can, at least with moderate and high-power lenses of the best 
modern construction, be anticipated. On this ground we commend 
the study to the earnest reader. 

Let RN, SN’ (fig. 87) be the spherical surfaces of a lens of 
density greater than air, and let P RS p be the course of a ray of 
light passing through it ; C, C’, the centres of the spherical surfaces. 

Let PR, RS be produced to meet the perpendiculars through 
Cand C’ in A and A’. 

Let CR=r, C’S=r’,' » = index of refraction out of air into 
the medium. NN’ =d, the thickness of the lens. NR=6, 
N’S=5’'. These may be considered as straight lines. 





Let the equation to PRbey—b =m (z—ON) . » (1) 

oe cae RS,, y—b =m'(z-ON) 
oy y—-W=m'(z—-ON) 2. (3) 
A Sp, y—am'(2-ON) 2 2 


From (2) and (3) 
bf —b=m (ON -OSN)am'NNan'd .. (3) 
Now sin CRA = p.sinCRB; 
Caen CAR=pz. CRinCBR. 
Now CA and CB are the values of y in equations (1) and (2) 
when = OC; 
ne CAShtm(OC-ON) Hb 4 mr; 
and similarly CBah4tmr; 
+ mr) sin CAR =p (b + wr) sin CBR. 
Now CAR, CBR do not in general differ much from each 


other, so that for a first approximation we may consider them to be 
equal, 


vw bt mraplb+m'r), ie pm’ =m — 











Let Hoda; thenpm’sm—bu. .. (6) 
; 
Similarly, sin C'S BY =p.sin CSA’; - 
CB! in gi pig Ck” Graig 
sin CBS =O sin A'S; 
or, og: Ease os sin C’ A'S; 


1 If either of the curvatures be turned in the opposite direction the sign of the 
corresponding r must be changed. 





110 VISION WITH THE COMPOUND MICROSCOPE 


and, as before, 
CB’ =b' + mr’, C’ A’ =b' + m'r’ from equations (4) and 
". a8 before we may take 

8 pm =p (b +m'r), or pm’ =m" — 










Let Be =’, then pm! : 
From (5) and (6) 6’ =b +™ an) 4 
rs 
» thigand (7) m= pm’ + bu! (1 -u) pman 
# # 
: 
and from (6) =m—bu+ bu (1 & en) 4 mda! 
# » 
=n(t % La) +8 (wu ee Ls 
# # 
Assume 
4 eh, Va E8 eg, Le eh wh a OE ek ‘ 
Bip uigalh » 
thee qo+hm) wreregl-hk=l. . | 


mi = hb + 1m)? 4 

Now let X, Y he the coordinates of P, the point from which the 
ray of light proceeds ; 

then by (1) é 





Y—m(X—-ON); 





substituting in (x) .X—0N); 
m! =k¥ +m(}—-kX—ON); 
whence 
h—g(X—ON) 





l—k (X-ON 


DIOPTRIC INVESTIGATION BY GAUSS TIT 


Also, if Y = 0, y=0; or if a ray proceed from E, it will after 
. ; m —kY 
refraction pass through E’, Also m = --™ Ee 0N) =" ”, that is, 
the ray will be equally inclined to the axis before and after refrac-- 
tion. 
E and E’ are called the ‘ principal points.’ 


dw 
oE=0n~-!~!a0n4 A 
rm 
=onyo7 7" 
E(u) — du 
du 
=on'4! 7% son's ‘wane 
w—u—duu 
=ON'+ ha 


poe) due 


Secondly : If m’ =0, or the ray be parallel to the axis after 
refraction, we have from (8) 


b=- im, and the equation to the incident ray becomes 


l e ‘= --on_?). 
yt m=m(s—ON), o yam(2 ON i 
; 14a" 
+. when y =0,e= ON +) =ON + 


wounduw 
= OF, suppose. B 


If m = 0, or the ray be parallel to the axis before refraction, we 
have from ® 


8 = 95 =" m', and the equation to the refracted ray becomes 


y— 7m" creme ory =m! (e-on'+ 4); 





k 
) ae 
o when y=0,2=ON'— 4 =0N'— capes cess 


= OF, suppose. : # 
F and F’ are called the ‘fueal points.’ 


OF=ON4_, BHae ) 
p(w au) — daw, 


—du i} 
p(w =u) — duu’ 








OF =ON'- 











‘112 VISION WITH ‘THE COMPOUND MICROSCOPE 
‘The focal distance —/= OF -OE=0F — ee 
‘” ; 
= iw =u)—duw ke 


Similarly, it may be shown that if there be two lenses, and sub- 
paylines refer to the first and second lens respectively, while 
E, E’, F, F’ refer to the entire system, and if 


i=O0E,-—O0E,, 
= — B= a (tym) — a a 


1% 


= — Fahl! = th) — dette, 


mim 
SMa era 
08 = On; —— see |? 


re se Sar 


OF =08, + Himba) (n+ 8) 
= aOR TCR: al 


of =o) — — Ml Fie) 
Hat) Hoy tat Oey ty 


We are now prepared to work out an example of the Gause system 
by tracing a ray through two or more lenses on an axis, showing how 
any conjngate may be found through two or more lenses on that axis,! 

ron ate at eect aay avon two or more lenses 
on an axis illustrated by means of a worked-out example, 

‘Two lenses, 1 and 2, fig. 88, or an axis xy are given. No. 1 is 
a double convex of crown ; inch thick, the refractive index p being 


1 Remembering our object aud the wuumed conditions of some for wham we 
write, we do not hesitate to preface this with the following notes to remind the 
rouder of the sense attached to certain mathematical expressions, 

ae means infinity. A plane surface of a lens ix considered a apherical surface of 
an indaite redins, “Any number divided by « 0; any number divided by O= m + 
Any niunber mnltipied by 0 0. a plus or minus, or multiplied by any number be 
mill 2. . 

‘The following are the rules for the treatment of algvbrajcal nigns: 

In the willtipiication or divivion of like signs the result ix always play; Imt if 
the xigus dew dissimilar it ix always senna. 

in mi, add all the terms together that have « plus sign: thet all the terms 

with a minus sign; subtract the less from the greater and aifix the sign of thw 
grater, Eixample : 





+3—ded a 
jim of the term to be subtracted and then add in 
~ Example: 

=3 

+2 





In subtraction change th 
accordance with the previons 








=5 

An example ocours in the annexed equations (x) and (xi), p. 14, 0f — + =m 4, 
wt then the + is changed into — by the negative sign in front’ of the fraction, 
In laa, P. 114, however, there being a + in front of the fraction, the rosult renains 
positive. 





ang VISION WITH THE COMPOUND MICROSCOPE 


In selecting the value of the focus to be put into the equations 
for both lenses, the last must be taken, that is, in lens 1 (iv), or 


+947, and in lens 2 (viii), or — 1-875. 

Tt will be noticed that the value of E being negative, it will be 
measured "314 inch to the left from P. Similarly, E’ is measured 
°622 inch to the left from Q’. 
tot * 128 to the left from E, and ¢! 128 to the right 


These four points, E, E’ and @, ¢’, are called the cardinad 
points of the combination. 

Here it must be observed that in this work it has been necessary 
for want of space to restrict the problem to lenses, that is, to: 
those cases where the ray emerges from the con into air, the: 
same medium in which it was tra on immergence, It is on 
that account that the values of and ' are the same. 

Having now obtained the four linal points, we may at once 

1 to find the conjugate of «. 
Let « equal the distance of the point « from the focal plane ¢, 
and y the distance of its conjugate from ¢$’. Then by formula (xiii) 
ey =¢'and es e=1 inch,y =! SBS4 16384. 
This numerically determines the position of the conjugate ie. 
Ti the rays incident on the combination are peetiriy ness 4 


aod’ y= £ =0, which means that y is coincident with $. 


‘The following is the graphic method of finding the conjugate of 

Vv. From V, fig 88, draw ae purallel to the axis to Bee E’, and 
the point where it meets E’ draw a line through N, the point 
where ¢' cuts the axix, to W. 

From V draw another line through M, the point where cuts. 
the axis, to meet E, and from the point where it meets E draw a 
line parallel to the axis, cutting the other line in W. W will be the 
contianis of vy, se “eed wees + 

it wired to find the conjugute of a ray ‘ing through 
three eect an axis, two of the lenses =o heeal ined anc 
their four cardinal points found. 

‘The principal points and the focal length of the third lens must 
then be calculated, and then combined in their turn by formule (ix), 
(x), (xi), and (xii), p. 118, with the cardinal points of the double com- 
bination. @ is taken as the distance of the tirst principal point of 
the combination, nearest the third lens, to the second principal point 
of the lens, nearest the combination. A fresh set of cardinal points. 
is determined in this manner for the three lenses. 

So also with four lenses ; the cardinal points of each pair being 
found, they are combined by the same formule, and new cardinal 

ints for the whole combination of four lenses are obtained. Simi- 
Tiny, the cardinal points of five, six, or any number of lenses can. 
he found and the conjugate of any point localised. 

Finally, no one need be discouraged by the appearance of the 
length of the calculation ; the example is given in full, so that any~ 








A PRACTICAL 


one acquainted only with 
vulgar fractions and deci- 
mals can work it, or any 
other similar problem, out. 

In lens No 1, for in- 
stance, the numerators of 
the fractions are all very 
simple, and the denomina- 
tors of the four equations 
are all alike ; 80, too, in 
the equations for Nu. 2 and 
in those for both lenses. 
Farther, 7” is the same as 
ff" asf", and ¢' as ¢. 


Hence the problem is much | 


shorter that it looks. 

If the conjugate of a 
point on the axie is only 
required, and if the prin- 
cipal points and foci of 
each lens have been de- 
termined, it will not be 
necessary to enter into the 
further calculation to find 
E, E’, and ¢, ¢’, the cardi- 
nal points of the combina- 
tion. 


The method of proce- 
dure is as follows : If x is 
the given point, its dis- 
tance from /f, the focus of 
lens No. 1, must first be 
measured. Call this dis- 
tance x. Then the distance 
of o its conjugate from the 
other focus, /’, supposing 
lens No. 2 to be removed, 
can be found by formula 





: 

oz= ft, 0 ay 

f= 897, «= 165; 
397 __, 
POT 543, 


aes i the distance from 


“As the distance. from 
x tof is positive, the dis- 
tance between f” and o is 
also positive ; 500 is to the 
right.of ’. : 


EXAMPLE AFTER GAUSS 











115 





Fic, 88, 


distans 
the distance of its cor a pay 
of No. 2 lens now Tan futon OF pes eamen pris 
Po=P/'+so=-947 +°543 = 149; 
PsP B+ BC+ Qf" = 121 4:25 + P875-= 24 ‘335 ; 
Pf! —Po=of'= 3335 — — 149 = S45. 
Calling this distance O, then, by formula yO=/'"" *, 1 we shall find 
the distance of y from /"", which we shall cally. y afee oy 
= 416, which ix Ue oabe therefore y lies 4-16 inches from f’” to the 
right t hand. yis therefore the conjugate of x, due to the influence 
of both lenses 1 and 2. Similarly, the conjugate of any poah on the 
avis may be found through any Ee of lenses. 


Lens No.1: Duta, —Badlins A= 4 =r; radius B= —1l=r; 
foci, ff’; thickness d;p=3; P= principal point men 
sured from A; P’ = principal point seam from B 

3 








=H=A4 158 4 Hi . » (i) 
2 


du 
SFE erases eer pres 





=aBai so . ~< Sas 


A PRACTICAL EXAMPLE AFTER GAUSS 117 


+ (iii) 







=P +947 
Lens No.2: Data—Radius C= — } =r; radins D 

foci, f", f’"; thickness = a =d;p=!s Q= principal point 

measured from C ; Q’ = principal point measured from D. 





8 
betes Bl 
= ag = ag? 
8 
r _8 8\_ 64, (aA 28 
p(w! w=§ (0+ f) 85 auw at x yp X 9 = 95 
is alae he 84g SOF Lge? 
#(w — 0) — duu = —0= 3 = 853; 
, 
Q=C+ ae =C+ a & 







Bu =u) —duw 


q=p+___@" ___op 


p(w —u)—duw 


=Q-1875  . . .e wii) 


Both Lenses.—Distance apart = BC = j= 2 5 PQ= 21425 


3; f= focus of No. 1 lens = -947 ; f’ = focus of No. 2 
— 1875, 





118 VISION WITH THE COMPOUND MICROSCOPE 


46x 947 4“ 
1947 — 1-875 46 = P t+ 
=P-34 . . . 
g— 46 x — 1875 
947 — 1875 — 46 
_ = 862 _ Gy _ go 
— 1386 = 2% CoE = 
947 x — 1-875 


E=P+, So apy 








— 1775 
— 1388 

947 x — 1875 
O47 — 1875 — -46 

wg — LTB 

HE 4+ 7 Rge b+... 
gt _ 16384 
x 


a 





=E—1-28 


¢ =E'+ 





ry=85 y= 





120 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


sun's rays asa burning-glass, and that these were used to produce 
ignition ; but there is no trace of suggestion that these 
could act as ‘ing instruments. 

Sencen (‘Quest. Nat.” i, 6, §5) states, however, that ‘letters. 
though and indistinct are seen en! and more distinct 
through u globe of glass filled with water.’ He also states that. 
‘fruit appears larger when seen immersed in a vase of glass.’ But 
he only concludes from this that all objects seen through water 
appear larger than they are. 

a ee rata Sasasisdge OF the ceiacnlan on pine aeRO 
and others no knowledge of the ciples on which refraction. 
took place at curved surfaces. 


Lg aaa Eatin att ge repent tbe ov 
ian Alexander dealt with myopy and ; Plutarch 


j 
treated of myopy, and Pliny on the sight. But no allusion is made 
to even the most simple optical aids ; nor ia there any reference to 
any such instruments by any Greek or Roman physician or author. 
In the fifth century of the Christian eva the Greek physician Actius 
says that myopy is incurable; and similarly in thirteenth 
century another Greek physician, Actuarius, vod that it is an in- 
firmity of sight for which art can do nothing. it since the end of 
the thirteenth century, which is after the invention of 

they are frequently to in medical treatises and other works. 

If we turn to the works of ancient artists we find amongst their 
cut gems some works which reveal extreme minuteness of detail and. 
delicacy of execution, and some have contended that these could 
only have been executed by means of lenses. But it is the opinion 
of experts that there is no engraved work in our national collection 
in the gem department that could not have been engraved by w 
qualified modern engraver by means of unaided vision; and in 
reference to some very minute writing which it was stated by Pliny 
that Cicero saw, Solinus and Plutarch, as well as Pliny, allude to these 
marvels of workmanship for the purpose of proving that some men. 
are naturally endowed with powers of vision quite exceptional in 
their excellence, no attempt being made to explain their minute 
details as the result of using magnifying lenses, 

These and many other instances in which reference to lenses 
must have been made had they existed or been known are con- 
clusiv ao it i, ee ied that even sishls dioptric bp : to: 
say nothing of cl microscopes and telescopes, cou! ave 
Tape Kiowa bo¥tie anclente without vatorenvo to tay having Asn 
made hy many writers, and especially by such men as Galen and, 





iny. 

‘The earliest known reference to the invention of spectacles ix 
found in a manuscript dating from Florence in 1299, in which the 
writer says, ‘I find myself so pressed by age that T can neither 
read nor write without those glasses they call spectacles, lately in- 
vented, to the great advantage of poor old men when their sight 
grows weak.’! Giordano da Rivalto in 1305 says that the invention, 

1 Smith's Optics, Cambridge, 1738, 2 vols, ii, pp. 12, 19, 





122 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 
spectacle inakers, of Middleburg, Holland, were the inventors. But 
‘it would that the earliest a for 
siersing ety reflected light only. ra\Loeeloa ta 

Pe ‘old microscope, Shey had been found ‘Middleburg a 
1876 an old mice i at WAS 
shown, which, Professor Harting considered, bt eee dn 
heen made by the Janssens. It is drawn in fig. 91, and consists of 
a combination of a convex object-lens and a convex eye- 
Jens, which form was not published as an actual con- 
struction until 1646 by Fontana, which, as Mr, Mayall 
points out, does not harmonise with the 
that this instrament was constructed by one of the 

Ele vise ly nal and the dis: 

is strictly a compound microscope, is 
id tance between the lenses can be regulated by two 
draw-tubes. There are three anne and the 

Jons lies in a wood cell, and is there by a wire ie 

sprung in. The object-lens, @, is loose im the actual 
2 instrament, but was originally fixed in a similar way 

to b. ¥ 

Tt cannot be an easy task—if it be even a pos- 

sible one—to definitely determine upon the actual indi~ 

_ Fio.®. vidual or individuals by whom the compound micro- 

Janson’ scope was first invented. Recently some valuable 

mierowoope, €vVidence has been adduced claiming its sole invention 

for Galileo, In a inemoir published in 18881 Pro- 

fessor G. Govi, who hus made the question a subject of large and 

zcntanees research, certainly adduces evidence of a kind not easily 
waived. 

Huyghens and, following him, many others assign the invention 
of the compound mie to Cornelius Drebbel, a Dutchman, in 
the year 1621; but it has been that he derived his know- 

from Zacharias Janssen or his father, Hans Jansson, 

makers, in Holland, about the year 1590; while Fontana, a Nea 
politan, claimed the discovery for himself in 1618, It is said that 
the Janssens presented the first microscope to Charles Albert, Arch- 
duke of Austria ; and Sir D. Brewster states, in his ‘Treatise on the 
Microscope that one of their microscopes which they presented to 
Prince Maurice was in 1617 in the possession of Cornelius Drebbel, 
then Mathematician to the Court of James L, where ‘he made 
microscopes and passed them off as his own invention.’ 

Nevertheless we are told by Viviani, an Italian mathematician, 
in his * Life of Galileo,’ that ‘this great man was led to the diseovery 
of the microscope from that of the telescope,’ and that ‘in 1612 he 
sent one to Sigismund, King of Poland.’ 

We now receive evidence through the researches of Govi that 
the invention was solely due to Galileo in the year 1610, Professor 
Govi understands by ‘simple microscope ' an instrament ‘ consisting 
of a single lens or mirror,’ and by ‘compound microscope’ one * con- 


2 Atti R. Acad. Soi, Pie. Ne Vapots. ‘Tl microxcopio composto: 
inventato da Galileo” Journ, RMS, Pt. TV. 1680, p. 674. 











124 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


‘Twill not now attempt to explain ull the perfections of this 
wonderful oechiale ; alone is a safe of the 





in animals pecially in a certain insect which has 
each covered by a rather thick membrane, which, however, 
frit gnreh olan, like the-visor ob a warrior; alice Steight 

Here hast thou a new proof that the glass concentrating its ra; 
the object ; but mind what Tam about to tell thee, viz 
animals of the same size and even smaller, some of which 
have nevertheless brighter eyes, these appear only double with their 
eyebrows and the other adjacent x 

After reading this document Govi judges that it is impossible to 


f 


refuse Galileo the credit of the invention of « co: microscope 
in 1610, and the application of it to examine some very minute 
animals ; and if he himself neither then nor for many years after 
made any mention of it publicly, this cannot take away from him or 
diminish the merit of the invention. 

Tt is not to be naires pode that. aa after these 
experiments quite forgot the microscope, for in 
Sas * between the end of 1619 and the middle Of October, 
1622, he spoke thus to Lotario Sarsi Segensano (anagram of Oratio 
Grassi Salonense) -— 

*I might tell Sarsi something new if anything new could be told 
him, Let him take any substance whatever, be iv stone, or wood, 
‘or metal, and holding it in the sun examine it attentively, and he 
will see all the colours distributed in the most minute particles, and 
if he will make use of « telescope arranged so that one can see very 
near objects, he will see far more distinctly what T say.’ 

It will not therefore be surprising if, in 1624 (according to 
some letters from Rome, written by Girolamo Aleandro to the 
famous M. de Peiresc), two microscopes of Kufiter, or rather Drebbel, 
having been sent to the Cardinal of 8. Susanna, who at first did not 
know how to use them, they were shown to Galileo, who was then in 
Rome, and he, as soon as he saw them, explained their use, as 
Aleandro writes to Peirese on May 24, adding, ‘Galileo told me 
that he had invented an occhiale which magnifies things as much 
as 50,000 times, so that one sees a fly as large as a hen.’ 

This assertion of Galileo, that he had invented a telescope which 

50,000 times, so that a fly appears as big as a hen 
must, without doubt, be referred to the year 1610, and from the 
measure given of the amplitication by the solidity or volume the 


126 THE WISTORY AND EVOLUTION OF THE MICROSCOPE 
Florence on nber 23, 1624, more than three months after his 
fon hens . ~ 


departure 
“Ts Excellency an occliatine, by which , 
sl tgs np age sal se and 


entertainment, as it does me. T have been long in sent 
a oll pega telera ving experiatead sume ay 


this or that part ; therefore the littletubeis 
or guide, as we may wish to call it. It must also be used in very 
bright, clear weather, or even in the sun itself, remembering that the 
object must be sufficiently illuminated. I have contemplated very 
many animals with infinite admiration, amongst which the flea 
most horrible, the gnat and the moth the most beautiful ; and it was 
with +t satisfaction that I have seen how flies and other little 
anit aan ee ing to the glass and even feet upwards. 
But your Excellency will have SP oetAey GE CLA at ee 
and thousands of other details of the most curious kind, of which T 
beg you to give meaccount. In fact, one may contemplate endlessly 
the greatness of Nature, and how subtilely she works, and with what 
unspeakable diligence.—P.S. The little tube is in two pieces, and 
you may lengthen it or shorten it at pleasure.’ 

Tt would be very strange, knowing Galileo's character, thnt in 
1624, and after the attacks made on him for having perhaps a little 
two much allowed the Dutch telescope to be considered his invention, 
he should have been induced to imitate Drebbel's glass with the two 
convex lenses, and have wished tomake them passashisown invention, 
whilst he had always used, and continued to use to the end of his days, 
telescopes with a convex and a concave lens without pace that 
he had read or in the least appreciated the proposal made by Kepler, 
ever since 1611, to use two convex glasses in order to have telescopes 
with a large field and more powerful and convenient. 

In any case it is impossible to form a decided opinion on such a 
matter, the data failing; but the very fact that from 1624 onwards 
Galileo thought no more of the occhialino (probably because he found 
it less powerful and less useful than the occhiale of Drebbel), as he 
had not occupied himself with it or had scarcely remembered it from 
the year 1610 to 1624, seems sufficient to show that the occhialino, 
like the microscope of 1610, was a small Dutch telescope with two 
lenses, one convex and one concave, and not a redu Keplerian 
telescope like that invented by Prebbel in 1621. 

The name of microscope, like that of telescope, originated with 
the Academy of the Lincei, and it was Giovanni Faber who invented 
it, ns shown by a letter of his to Cesi, written April 13, 1625, and 
which is amongst the Lincei letters in the possession of D, B. Bon- 
compagni. Here is the in Faber’s letter :-— 

*T only wish to say this more to your Excellency, that is, that 








128 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


that rain year 1000, me eeyel | to | in- 
be 7 7 pl 80 

Sha erenoe “attra 2 "airs 

Majus,’ dedicated and by him to Clement TV., could show: 


weakened, who in such a way will be able to see the letters suf- 
ticiently enlarged, however small they are.” As no documents 
anterior to him are discovered, Roger Bacon may be considered the 


had discovered ; that is, th 
use of converging lenses for long-sighted 
people, and of diverging lenses for 
sight, whilst the English monk had only 
spoken of the lenses for long sight, and 
perhaps they added to this first invention 
the capability of varying the focal lengths of 
the lenses according to need, and the other of 
fixing them on to the visor of a cap to keep 
them firm in front of the eyes, or to fasten 
them into two circles made of metal, or of 
bone joined by a small elastic bridge over the 
nose. However it may be, the discovery of 
spectacles, or, as it may be called, of the 
stmple microscope, may be equally divi 
between Roger Bacon and Salvino li 
: Armati, leaving’ especially to the latter 
Fa wep o' siimplo invention of spectacles. 

tmiorowoope with reflvotor, The earliest known illustration of a 
imple microscope is given by Descartes in 
. 92 reproduces it. It is practically 
ieberkihn a century after and shown 










his ‘Dioptrique’ in 163: 
identical with one devised 





“GALILEO'S’ AND CAMPANI'S MICROSCOPES 129 


on p. 138. A lens is mounted in a central aperture in n polished 
concave metal reflector, (25 porter Bee and 
much tore pretentious instrument, but poe impracticable 
and could never have existed 

save as a suggestion. But he 
sine eee first 
pul figures and deseri) 
fica te pricinarar politi: 


lenses. 
In the Museo di Fisica there 





“Fro. 94-—Campant's microscope 
(t 1040) 


are two small microscopes which 
it is affirmed have been handed 
. down from generation to gene- 
ration since the dissolution of 
the Accademia del Cimento in 
1667, with the tradition of 
Fo, 88,~ Galileo's microseopes. having been constructed by 

Galileo, ‘They are shown in 
it from the superiority of construction of these instru- 
i is i le that they belong to the days of Galileo, 
who died in i823} and there is’a specially interesting compound 
K 








430 THE HISTORY AND EVOLUTION OF THE MICROSCOPE) 
























microscope, by Giuseppe Campani, which was published first in 
which is presented in fig. 94 ; its close similarity to ‘Galileo mi 
scopes” is plainly apparent, making it still. more improbable 
these could be given a date prior to 1642. 
journal of the travels of M. de Monconys, publi 
there is a description of his microscope which is of 
He states that the distance from the object to thea 
is one inch anda half; the focus of the first lens is oneil 
ance from the first lens to the second is fifteen 
inches ; the focus of the second lens, one inch and a half ; 

distance from the second to the third, one inch and 

eight lines; the focus of the third lens, one inch and 
eight lines ; and the distance from the eye to the third 
lens, eight lines. 

This would form the data of a practical com- 
pound microscope with a field lens ; and as Mon- 
conys had this instrament made in 1660 by the 
‘son-in-law of Viselius,’ it becomes probable in a 
very high degree that to him must be attributed 
the earliest device of a microscope with a field- 
lens. 

In 1665 Hooke published his * Micro- 
graphia,’ giving an account and a figure of 
his compound microscope. He adopted 
the field-lens employed by Monconys and 
gives details as to the mode and object 































4132 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


Se Ne seers TIC ee 
convex lens, two jo-convex lenses were applied wi 

Se eee ina ean erehiae he claimed to obtain a much 
flatter field. Mr, Mayall found in the Museo Copernicano at Rome 
a microscope answering 80 closely to this description that he does 
not hesitate to refer its origin to Divini. pple de as 

ore 
But the opt tical con- 


Chérubin d'Orldans 
published, in 1671, @ 
‘treatise containing a 
design for a micro- 

, of which fig. 
97 is an illustration. 
The scrolls were of 


encircling the fixed 
central portion of the 
body-tube. An ex- 
Pete sliding tube 
carry 1OCe 
shove x Nance 
tube, and a similar 
sliding tube carried 
the object-lens below, 
these sliding tubes 
serving to focus the 
image and regulate 
(within certain limits) 
the — magnification. 
He also suggested a 
serew arrangement to- 
be applied beneath 
the stage for focus~ 
sing. He devised, or 
recommended, seve- 
ral combinations of 
Fio, 97.—Chérubin d'Orléans’ compound microscope. lenses for the optical 
part of the imicro~ 

scope, and refers to combinations of three or four separate lenses, 
by which objects could be seen erect, which he considered ‘much to 
be preferred. 
He also invented a binocular form of microscope and pablished 
ithin his work, ‘La Vision Parfaite,’ in 1677. It consisted of two 
compound microscopes joined togéther in one setting, so as to be 











al 





| 


{34 THE HISTORY AND EVOLUTION OF THE aNCROSCOPE 


‘note and diagram) for a reflecting “0 3 we"! however, 
began to send to the Roynl Society his ‘ 
was 





nts, except 

120 "We now, however, ha his misnope wee cre 
Sere eee nes een le bi-convex. 
with worked surfaces mounted between two plates of thin 
with minute apertures through which the objects y soon. 
At his ssmes oth Taal Saat analy pe IX 
of his microscopes to Royal Society ; unl >. 
mysteriously disappeared. But Mr. Mayall was enabled to figure 
ta: ‘s one bg eo gr reno 

~ of the Utrecht University, 
which is given in figs, 1 
and ,101 in full size, It is 
seen on both sides. The lens 
is seen in the uy third of 
the plate. It a j-inch 
focus. The object is held 
in front of the lens, on the 
point of a short red, with 
serew arrangements for ad- 
justing tlie Oijee na beetbe 


lens, 

Many modifications of 
this and the preceding in- 
struments are found with 
some early English forms, 
but no important construc. 
tive or optical modification 
soma aa) presents itself. 

ut some ingenious arrange- 
ments are found in ae 
simple microscopes devi 
Fro. 100. Fio. 101. by eoaree a in the 
Tecuwenbook's microscope, carly years of the eighteenth 
century. 

Grind! figured a microscope in his * Wicrog ante Nova’ in 1687, 
in which optical modifications arise. Divini had, as was stated, 
combined two plano-convex lenses, with their convex surfaces facing, 
to form an eye-piece: this idea was carried further in 1668 by a 
London optician, who used two pairs of these lenses ; Grind] did this 
also, but in addition he used two similar (but smaller) lenses in the 
same manner as an objective. The form of the microscope itself 
was copied from that of Chérubin d'Orléans (fig. 97), but was 
moditied by the application of an external screw. ' 

In 169} Bonanni modified preceding arrangements by devising 
4 means of clipping the object between two plates pressed Away from 
the dbfect-lens by 4 spiral spring, the focussing being then effected 
by @ ‘screw barrol.” 











137 


HERTEL'S MICROSCOPE 





‘Fro, 104.—Hertel's microscope (1716). 


138 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 





iit th lm tnt In ‘Marshall's 
defective, wit 

ope a er ra sp 
now i luring tl 

ould rami steal in the Sed (2) A forks NY, is here ay 
with a thumb-screw clamp, ton ie pil tsolf, (3) Hooke's 
Sad-sockot joint, which wes applied to tho arm T, is here shifted to 


the lower end of the pillar, where it would the of 

inclination to the whole mi higeoonearnalce? hy the 
as in Hooke’s ; the ball L coul tightly 

calla M, in which slots were oe to bape 


lens on jointed arms aj 8; this prol ei 4 
of such adjustments to condenser. From the wifey tat 
the candle beneath the condenser, we may infer, wit eae 
the Seria > still unknown as a microscopical 


eat no microscope up to this time has there been any 
trace of, or reference to, a yee but in 1716 Hertel panaeaine it 
and introduced some other considerable modifications. ‘The general 
appearance of the instrament as originally figured by Hertel is given 
in fig. 104. Not only have we the mirror below the stage, but also 
above the stage a concave metal mirror reflecting light through a 
condenser on the object, while the stage is movable on a pillar 
a The body-tube is hinged and is inclined by a serew-sector 
mechanism. 
Tu 1738 Dr. N. Lieberkiihn devised, what had been employed 
in principle by Descartes a century before,! the instrument that has 
ever since been known by his 
name, and which is still of con- 
siderable value to the micro- 
scopist. Fig. 105 is a luc- 
tion from the earliest drawing 
known of Lieberkiihn’s micro- 
scope, A A is a concave mirror 
> iver ; from its form tholight 
% is reflected from it to a focus on 
Bia, SOKesLisberkiiha's mieroesopo. the chiect C. ‘The mirror, ie 
pierced in the centre at B and the lens, or object-glass, is inserted 
and adjusted, the eye being placed behind in the direction D at any 
point the single lens or « combination might require. 

*A Pocket Reflecting Microscope’ was figured by Benjamin 
Martin in his ‘ Mierographia Nova' in 1742, having the interesting 
feature of a micrometer eye-piece depending on a screw with a 

1 Seo pp. 128-9. 








140 THE HISTORY AND EVOLUTION OF THE cKO 

















wheel]. ‘The arm, I, supporting the compound body, is supplied #4 
a rack and pinion, K, by which it can be moved backwards and 
wards, and a joint is placed below it, upon which the body cau 
turned into. horizontal position ; another bar carrying a stage al 
mirror can be attached by the screw, LN, so.as to convert it into) 
horizontal microscope. ‘The stage, O, is provided with all.the wail 
apparatus for clamping objects, and a condenser can be applied toi 
under surface ; the stage itself may be removed, the arm, P, 
porting it, turned round on the pivot C, and another stage § 
exquisite workmanship placed in its.stead, the under surface 
which is shown at Q. 

‘This stage is strictly a micrometer one, having rectang 
movements and a fine adjustment, the movements being ace 
plished by fine-threaded screws, the milled heads of whi 
graduated. The mirror, E, is a double one, and can be 
depressed by rack and pinion ; it is also capable of removal, 
apparatus for holding large opaque objects, suchas minerals, 
substituted for it. The accessory instruments are very num 
and amongst the more remarkable may be mentioned a tube, My@ 
taining a speculum, which can take the place of the tube, R, am 
form a reflecting microscope. The apparatus for holding animale 
or other live objects, which is represented at S, as, well as a plate 
glass six inches in diameter, with four concave wells ground m ij 
can be applied to the stage, so that each well may be brought 

accession under the magnifying power. The lenses. belongin 
this microscope are twenty-four in number ; they vary in fi 
length from four inches to, one-tenth of an inch ; 3 ten of them 
supplied with Lieberkithns, A smallarm, capable of carrying 
lenses, can be applied at T, and when turned over the stage the 
strument becomes a single microscope ; there are four lenses suit 
for this purpose, their focal length varying from +,th to 2jth of} 
inch. The performance of all the lenses is excellent, and no, p 
appear to have been spared in their construction. There 


































THE VARIABLE MICROSCOPES 





= 
—> 


a 
as 


142 THE HISTORY AND EVOLUTION OF THE MICROS 














improvements ou all previous constructions. He applied oa 
third near B, and a fourth in the conical pai 

3, by which he increased ‘the field of view at oF i 
draw-tubes were at A and B, by which these lenses could be s 
more or le He also arranged the object-lenses, or ‘butta 
and 4, to be combined ; seven ‘buttons’ were provided, ‘alsa 
silver specula [‘ Lieberkihns ’] highly polished, each having a ma 








fier adapted to the focus of its coneay vhich is repre 
at ¢, and the ‘buttons’ could also be used with ‘ any one af 
specula” by s of the adapter, d. 


The body tube, A BC, with its arm, F (in which it screwed 
and stem attachment with the fine adjustment were clearly n 
froma design which Cuff ted. The large ivory head, I, act 

i nd rack for raising or depressing the body-attachmél 
The stage and mirror were adjustable on the stem. 
wheel controlled by the pinion-handle, S, gave 
required inclination to the stem. 




















applied in the sprin, 
3) is to receive the was a diaphragm 
in the lower end af No. 3, ‘to exclude some part of the light W 
is reflected from the mirror Q.’ The forceps, No. 5, could be 
‘in one of the small holes near the extremities of the stage, or 
socket, R, at the end of the chain of balls No. 6.’ No. 6 was an 
composed of a series of ball-and-socket joint 
employed by Musschenbroek, by Joblot, and by Lyonet, and was 
tended tobe applied at W, when the stage w: i 
a box of ivory in which discs of tale and bra 
No. 8, a hand-magnifier ; No, 9, a sliding arm lens-carrier fitting y 
Z, when the instrament was required to be used as a simple m 
pe ; No. 11, a rod of wire with spiral at the end for picking 
soft objects from bottles & and No, 12, an ivory disc, black 
one side and white on the other, fitting at T, to carry opaque objett 



























144 THE HISTORY AND EVOLUTION OF THE MICR 


Isaac Newton in 1672, and one was devised on the principle 
Gregorian Telescope by Barker in 1736 ; another of the 
form was made in 1738 by Smith, which was, perhaps, 
perfect of the Catoptric forms. 

An outline of its construction and the path of the 
given in fig. 109. It was for examining transparent objects 
similar to the Cassegrainian telescope, but with an extra 
piece tube to permit the focussing by movement of the 
The ‘object was placed at MN ; the image was taken 
concave, reflected on the convex, and again reflected to the 
He advised the use of a condensing lens for the illumination, 
vent ‘the mixture of foreign rays with those of the object,’ 
the instrument gave confused images of distant objects when i 
used as a microscope. 

Even without a condenser there are good images attainable 














146 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


rp eediehy two biconvex crown-glass lenses, and a biconcave 
flint lens ) 
C. Chevalier tells us! that between 1800 and 1810 M. Charles, of 
the ‘Institut,’ Paris, made small achromatic lenses ; but they were 
too imperfect to be of real service. Tn 1811 Fraunhofer made 
achromatic doublets with no great success ; and in 1823-4 an achro- 
matic microscope was made by the Messrs, Chevalier, with four 
doublet lenses arranged ling to a plan devised by Sellique. 
‘Their ‘ Microscope d’Euler’ followed, and in 1827 Amici constructed a 
horizontal microscope 
ey eee princi- 
les, w! was spoken 
well of. But while 
up to a very recent 
date it was common 
to assert that the first 
to the plan of 
combining two, threo, 
or four pl CONVEX 
achromaticdoubletsof 
similar foci, one above 
the other, to increase 
the power and aper- 
ture was Sellique in 
1823, it isnow known 
that this had been an- 
ticipated by Marzoli 
(ch. v. p. 302). Sel 
lique’s plan was car- 
ried into execution by 
the Messrs. Chevalier. 
The instrument em- 
bodying this plan is 
shown in fig, 111. 
Ina to the 
Académie Royale des 
ae, , Sciences, the well- 
Hic: 231, Gelliqoe' wahromile intorescops (Rt) a eran 
Fresnel says, concerning this microscope, that in comparing the ob- 
jectives with those of one of Adams's best non-achromatic instruments 
—that up to magnification of two hundred times—Sellique’s was 
decidedly superior ; but beyond that magnification there was no 
superiority in the achromatic form, and he preferred Adams's form 
for prolonged observations because it gave a larger field than 
Sellique’s. 
mechanism of this microscope was similar to the English 
model of Jones, shown at fig. 108. The focussing was by rack and 
pinion acting on the stage, the pinion remaining stationary and nob 
travelling on the rack, Two draw-tubes, A and B, were applied 











1 Des Microteapee, Paris, 1899, p. 80, 


— 


148 THE HISTORY AND EVOLUTION OF TIE MICROSCOPE 
‘it was needful to use in order to secure a fair i the objectives: 
‘by permit- 


An extremely rian dean teeastele esters) apcry ad 
probably not long after 1 and bearing much resemblance to that 
Bal Bella ieahows in oe me is i with a ppening. 

iso of ay w the chamber under 
ee and this iow plan which obtained 
a permanent place in the miero- 
scopes of the future. 
Gartine = aioaiatis 
i ique’s tic 
i determined Professor 


microscope 
Amici, who for nine years had 
abandoned his experiments on 
achromatic object-glasses, to re- 
commence them in 1826, and in: 
1827 he exhibited in Paris and 
in London a horizontal micro- 
scope. The real novelty shown 
in it was the application of w 
right-angled prism immediately 
above objective to deflect 
the rays through the horizontal 
body-tube, ‘The object-lassex 
were i jan of three lenses 
superposed, each having a focus 
of three lines and a greatly in- 
creased aperture. It had also 
extra ye-pieces by means of 
which the amplification could 
he increased. 

Meantime the subject of 
achromatism was engaging the 
attention of the most distin- 
guished English mathemati- 
cians. Sir John Herschel, Sir 





Fre Nemeope HS George (then: Professor) Airy, 
Professor Barlow, Mr. Cod- 

dington, and several others, worked with some vigour at the subject. 
0, for some years, Joseph J. Lister had been earnestly working 
experimentally and mathematically on the same subject, and he 
discovered certain properties in an achromatic combination, which 


‘were of importance, although they had not been before observed.! 
Tn 1829 a paper from Lister w cived and published by the 
Royal Society,* and putting the principles it laid down into practice, 
Lister was enabled to obtain a combination of lenses capable of 
transmitting a pencil of 50° with # large corrected field. This paper 
and its results exerted a very powerful influence on the immediate 
improvement of English achromatic object-glasses, and formed « 
1 Fide Objectives, Ch. V. p. W04, ? Trans. Roy. Soc. tor 1829. 









150 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


er basis of advancement for the microscope, not only in 
its optical, but also indirectly in its mechanical construction and 
refinements. 

For convenience, at 
this point we may ad- 
vance a little in order to 
complete our brief out- 
line of the mechanical 
application of achroma- 
tism to object~ 
Mr. A. Ross e 
practically acquainted 
with the principles of 
achromatism as applied 
to combinations of lenses 
in working with Pro- 
fessor Barlow on this 
subject, and having ap- 
plied Lister's principles 
with great success, he 
discovered, as we have 
elren poten out in 
Ch. 1! that by covering 
the object under exami- 
nation by « thin film of 
glass or tale the correc- 
tions were disturbed if 
they had been adapted to 
an uncovered object; and 
we have seen that it was 
in 1837 that Ross de- 
vised a simple means of 
correcting this. He was 
an indefatigable worker 
in the interests of the 
advancement of the me- 
chanical as well as the 
optical side of the mi- 
croscope. Fig. 114 pre- 
sents an early form of 
one of Ross's carliest mi- 
croscopes, from an extant 
example, which is n form 
issued under Pritchard's 
name. The stage is 
actuated in diagonal di- 





Fro, 115.—Pritchard’s micros with ‘Continental* a =, r 
cee ee adja omanenlAl” yections on either side of 


the stem, and its general 

form coincides with one which Mr. Mayall assigns to Andrew 

Pritchard, which fig. 115 illustrates. It has the same kind of stage 
‘P20. 





154 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


What are the attributes of the instrument without the possession of 
ae it cannot meet modern. cab 4 
I. Steadiness is absolutely indispensable: this would, in fact, 





156 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


i for and moderate power objectives of ten inehew ; 
Sanegrern eee vee "Tho mechanical tube-length 


tee ‘Abbe, in constructing his apochromatic objectives fo 

consi atic ol ives for 
the English body, has taken the mechanical tube-length at 98 
inches = 250 min.; and the optical tube-length at 10-6 inches 
=270 mm. This has caused an increase in the length of the English 
standard tube, since all good microscopes are made to work with 
‘these ives ; and the addition of «rack and pinion ta the “draw- 
tube’ becomes of great ‘ical value. 

The tube-length of the Continental mechanical tube is 6°3 inches 
= 160 mm., and (rea esse ck is 7-08 inches = 180 mm, 

The question has been asked, * Which is the better of these two 
differing tube-lengths?’ So far as the image in the instrument is 
concerned, there is not much difference. It is of little importance 
whether the initial magnifying power of an objective be increased 
by a slightly lower eye-piece used at a longer distance or n slightly 
deeper iglier) eye-piece ata shorter distance. But it is of i 
importance to note that « ama/t difference of tube-length produces « 
greater effect on adjnatment with a short body than with « long one. 
The principal difference, however, between the long and the short 
body as affording a datum for their respective values is that when 
a short body is used by a person having normal accommodation of 
wight, the stage of the microscope cannot be seen unless the head is 
removed from the eye-piece, whereas with the long body the eye 
need not be taken from the eye-piece at all, as the stage can be seen 
with the unused eye, 

TH, Arrangements for focussing stand next in order of import- 
ance. Every microscope of the first class is provided with two 
arrangements for focussing, one a coarse adjustment, acting Sao 
and the other a fine adjustment, which should act with great ceed 
and precision. A good ‘course adjustment’ or primary le 
part of the instrument is of great importance, ‘The first requisite is 
that the body or movable part should move ensily, anor ely but 
without ‘shake in the groove or slot or whatever else it slides. 
We have found in practice that a bur shaped like a truncated prism 
sliding in a suitable groove acts best and longest. But a bar planed 
true and placed in a groove ploughed to suit it is not enough. The 
inevitable friction determines wear, and this brings with it a fatal 
‘shake,’ All such grooves, which are usually V-shaped, should be 
cut and sprang on one side, s0 that by ‘tightening up’ the Vis by 
means of screws the bar or limb is again firmly gripped. Further, 
the bar should not ‘bear’ for its whole length along the groove, but 
only on points at either end and in the middle. Powell introduced 
these prime essentials to a good ‘coarse adjustment’ half a century 
ago; yet what thousands of instruments in which these principles 
have not been applied have heen, by sheer friction wear, soon 
changed into useless brass since then! But instruments made by 
this firm are as good after thirty years’ use as they were when new, 

Frequently bad workmanship is concealed by the free employment: 
of what is known as ‘optician's grease’ and an over-tightening of the 





a 


158 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


t purposes absolutely useless, what are otherwise 
‘instruments of excellent \ and real ran 
‘There are two kinds of fine adjustment — 


ii, “Those which mova sha whole bodly,/or tha whole body including 


‘the coarse adjustment. 
construction of the second class has proved impracticable, 
-and even pernicious. It inevitably breaks down just asthe purchaser, 
by ji easccdl Coispitcae the walsp  cporback pote 

all dans hye edtibrl pee syn Ut 
Be ease re eats ence See tever value it 
at 


‘To this broad statement there are pesiniy two exceptions, inven- 
tions still «uh judice, viz, Swift's side lever and Campbell's differential 
screw, to which we shall subsequently refer. 

. Tt is, celeb ‘upon this erat all oe radical and giing 
imperfect et the majority ental microscopes are 
A screw of an extremely tina thread, and therefore of extremely 
shallow incision—a micrometer screw in fact—fure to bear the werar, 
lifting and lowering the entire weight of the body, with its coarse ad- 
justment, lenses, and so forth ; while the sole object of the adjustment: 
should be to give a delicate, almost imperceptible, motion to the 
object-glass alone. Tt needs no great experience to foresee the inevi- 
result ; the screw loses its power to act, and something incom- 
parably worse than a tolerable coarse adjustment is left in its 
‘Yet it is the Continental model that has become the darling of 
English laboratories, and that still receives the appreciation of pro- 

‘ fessors and their students. True they answer in the main the 
purposes sought—the exigencies of a limited course of practical in- 
struction. But how many of those who receive it are the medical 
men of the future, and to whom a microscope—not of necessity a 
costly one—of the right construction would be of increasing value 
through a lifetime ? 

Imost' any instrument, however inferior, could be employed 
successfully with a 4-inch objective. of ‘low angle’ (to give it what 
has been called ‘the needful penetration’ for histological subjects !) 
to obtain an image corresponding to a figure in a text-book of, say, 
a ca eae corpusele, or a section of kidney, brain, or spinal cord. 
‘The quality of a fine adjustment is never tested by these means, 
for, in point of fact, a delicate fine adjustment is not even necessary. 
We write in the interests of microscopical research. It certainly 
may be taken for granted that the end sought is not simply to use 
the microscope to verify the illustrations of a text-book, a treatise, 
or n course of lectures ; without doubt it is a subsidiary purpose 5 
but the larger aim is to inspire in the young student confidence, 
enthusiasm, and anticipation in the methods and promise of histology 
and all that it touches. But for this there must be potentiality 
(without costliness) in the mechanical and optical character of the 
microscopes commended and approved. 

A low-priced student's microscope of good workmanship and 





ae 


160 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


adjustment, is in one solid piece, If nothing were sacrificed this 
SE lh Re oa acter uP lied with a fine 
adjustinent which mu the nose-piece, but on a principle 
NEE al te eet ath tn chad err 
abandoned, and the solid Jackson arm was cut, the whole body 
and its coarse adj it was pivoted on the lever of the tine ad- 
justment. Thus its normal virtue (« solid limb) was sacrificed, and 
a ‘fine adjustment,’ doomed to failure, was given to it. 
A complex roller, a wedge, and « differential serew have in turn 
been since employed to re- 
deem this instrument from 
‘the failure that had over- 
taken it. Partially, or com- 
letely, each has . The 
lifferential screw certainly 
comes theoretically nearest 
to success with this form of 
instrument. But at the out- 
set this is the case only where 
it wholly abandons the lifting 
and lowering of the body-tube 
&e, by the action of a ‘fine 
atest and its motion is 
only brought into operation 
upon the equivalent of a nose- 
piece. The form specially 
adopted for this instrument: 
was devised by Dr. Hu; 
Schroeder, and is a remark~ 
able arrangement, worthy of 
being understood, Tt is illus- 
trated in figs, 122 and 123, 
The nose-piece, A, is at- 
tached to a tube which is 
fitted to slide accurately in 
adjustable bearings in’ the 
body-tube, B. The nose- 
Paes: Fi. 18 piece tube has a short pro- 
Schroeder's fine adjustmant for the Jackson jecting arm, C, by means of 
com which it is pressed upwards 
bya strong spiral spring mounted in a cylindrical box, L, outside the 
lower end of the body-tube. Thearm, C, is moved against the spring 
the differential-screw mechanism (with milled head, D), which is 
gitmballed on a bracket, E, attached to the upper part of the body-tube. 
The differential-screw mechanism consists of a steel rod, F (con- 
nected with D), which has two screw threads at the lower end, one 
working in a thread cut in the end of the inner tube, G, and the 
other in the block, H, which is soldered within the sheath, J. 
When the nrilled head is turned to the left, the block—and with it 
the sheath—moves downwards, while the rod itself, carrying the 
block und sheath, moves upwards, As the screws are cut respec~ 








7 


162 TEE MISTORY ASB EVOLUTION) OF: THE AELGROGCORE 


forsisiet the Juckton:modshwasiknown as the short-side lecer, and 
‘it was sometimes employed in the commoner baranovement micro- 
Tes n and character will be seen on the r 





qeatety nasa ithe Gomsned oh le Sc aia 
steadiness of movement does not belong to it. It is only that it 
‘was concurrent with the belief in ‘low angles,’ and comes ee fps 
tration,’ in objectives (with which no critical work could be ye 
that it is possible to account for the toleration for so long in num- 
bers of Buslish microscopes of this pre inotiicient adjustment. 





wyl's vertical lever is one 

a pee of vel new forms of tine adjust- 
tment worthy of careful trial; it 
has in it aacaite of groat merit, 
It can, however, only be applied to 
the Jackson model, and promises to 
redeem that instrument from what 
must otherwise have proved its 
extinction’ as a tinst- micro 


scope. 

The firat form of this adjust- 
ment was sound in principle and 
ingenious in construction, It is 
ditiicult to know why the inventor 
and patentee has abandoned it 
for another, the value of which 
as a modification hns yet to be 
established, : : 

The early form employ by 
Swift avoided what hal eet a 
sheer necessity of all successful 
fine adjustments of this type, viz. 
the accuracy and perfection of the 
fitting of the nose-piece tube. This 
was done, as shown in fig. 124, by 
attaching a vertical prism- 
bar, A, to the nose-piece, and 
ing this in V-grooves in a box at 
the back of the body. A horizontal 
micrometer screw with a milled 
head, F, acts on a vertical bent 
lever, D, on which a stud, E, fixed 
to the prism bar bears. 

There is also an adjustment for 
Fig. 14.—Swift'epatentfineadjaxtinent, tightening up the prism bar in the 

V-grooves, BB. Side shake and 
‘loss of time’ are impossible with this form of adjustment ; while the 
power to ‘tighten up' by means of the capstan-headed screws 





a 


me THE HISTORY AND EVOLUTION OF THE MICROSCOPE 
makers have returned to the former plan 


rae hand of the Abescpersinniit saat senily 
ata frit poe, ph ane La eae 
te the manipulation of these instruments: to be 

The Suter loon ok this | msc sng sn peel reverting to 
the heeds tink we have seen to condemn—of 

throwing ig upon the fine-ndjustment Pea the entine 
body. A Jackson limb fitted with "this x movement has two slides— 
‘one for coarse adjustment, which aoe the entire , including 
the fine-adjustment box; in front of this is a second or ex- 
cavation for the justment movement of the body only. The 
mechanism is shown in fig. 126; itis precisely similar to that in 
fig. 124, with tho exception thnt the stud on which the lever bears 
is Best to the ‘instead of ta the nose-piece-slide, 

By this very, mechanism the fine adjustment is applied on 
the front of the the coarse adjustment, and acts on the whole body-tube 
and not merely on the nose-pieoe. 

There remains one other form of this adjustment i be con- 
sidered ; it ig « of differential screw devised by the Rev, J. 
Campbell, of Fe Shetland. Its object is to supplant the direet- 
action screw, where the form of the microscope may appear to make 
that a necessity, This has been the case with the Continental 
model. It was applied by its inventor to a microscope made 

himself, and was brought before the Quekett 
Ws Mr. Sa ie sds 

mple, and is made cutting 

two Niitane the micrometer serew. Big. 12 27 
will illustrate the exact method. D is the walled 
head of the direct-acting screw. The upper part, 8, 
of the screw has (say) twenty threads to the inch, 
and the lower part, T, twenty-five threads to the 
inch. Bis the fixed socket forming part of the limb 
af the microscope, and H is the travelling socket 
connected with the support of the body-tube. 
The revolution of D causes the screw thread S$ 
to move up and down in B at the rate of Slee 
cae to - inch, ae the screw see causes 
the travelling socket H to move in the reverse 
Ltr yan direction at the rate of twenty-five turns to the 
fine adjustment. inch, The combined effect, therefore, of turning D 
twenty revolutions is to raise or lower T and with 
it the body tube ith of an inch, or ;}oth of an inch foreach revolu- 
tion. The spiral spring below H keeps the bearings in close contact. 

Of course any desired can be attained by proper combina- 
tion of the irene thus 32 and 30 would give ylyth of an inch 
for each revolution, and 31 and 30 would give sath of an inch. 

This screw has provided for the Continental model what Swift's 
vertical lever has done for the Jackson model; Mr, Baker, of 
Holborn, has ado) it and with very satisfactory y results ; for it 
has passed through that most crucial of tests for a fine adjustment, 











7 


166 THE HISTORY AND hid OF THE MICROSCOPE 


Pi Repeater a ifs grat lity ity fi instantly’ ee 
ducing any motion required without removing the hand from ite 
position ; a most Seltatents acpi ikealt oes 
ments of 4 living and minute. followed. 

Tt still further enhances sick sage pi inion is carried right 
airoage aren, with a milled head 


of mechanical stage Sars ean eee 

jee in this country. OWA Tease Bo ae tools totes 
satis peste No cmc flexure is inevitable and 
is impossible. Its character will be understood from 


1. Plates s0 nies emery Ta! they ok ik rigidity. 
2. The Rees late is only supported on one side, 
3. The Turrel 


milled heads are placed vertically on the top of ue 
nh 


in actual work, 
We have ae 
ee ree 
at tl ie 
of a isgiete 
should be nla 
gradvated to hin 
rredths of an inch aw 
finder, and the 
principle on which 
they should be con- 
structed and  em- 
ployed is given under 
that he in detail. 
On the upper stage 
plate there should be 
‘a lodge for the slip to: 
rest upon and a slop 
at the left-hand side 
beyond which it can- 
Fis, 198,—The Tollos mechanical stage alopted — uot be pushed. This 
wae should be removable, 
but capable of being replaced with absolute precision as to position. 
The aperture in the stage should always be large, at least two 
inches in diameter. There ought always to be space enough above 
tle ordinary slip when it is in position to permit of the easy inser- 
tiva of the index finger, for by its proper use, focussing with the 
highest powers may be greatly facilitated. The object is to raise or 
lower the slip, as the objective approaches the object, so as to dis- 
cover how nearly it may be to contact with the front lens of a high 
power in approaching focus. The focal distance should always be 
felt nnd not sought with the eye. 





| 














‘LUTION OF THE MI 





ISTORY AND 





ts the pinion engages the mck so lightly that 
In others the piniom 





made inctram: 
rapid motion 1 
be disengaged and rapid movement effected. 
The « { rotation of the stage should be 
to cine: with the optic axis, so that in 
should never be out of the field when a fairly high power 
Elaborate rectangular centri has been used by som 


ay easily be given to it. 
































172 THE Hist 





AND EVOLUTION OF THE MICROSCOPE 






imposed, All mirrors should be so mounted as to admit of 









The present Editor is greatly in favour of the emplupnent 
ctangular prism cut with care and precisim. We get 
means total reflexion and no double reflexions ; and he 
that finer images can be obtained by its means than with 
anirror. It may be mounted in the place uf’ the plane mit 
is to say, the coneave mirror may be.as usual in its cell 
other cell, which would have received the plane mirror, 
salar prism may be mounted and be capable of rotation as 
mirror would have heen. 

It should, however, be noted that this applies only when 
light is required to be retlected at an exact right angle. “It is of 
xreatest service when the microscope is of neeessity used in a righ 

tht position 
It i be used for angles other than right angles, there will 
raction as well as reflexion ; and as the necessary decompositiot 
of the light into a -trum will accompany the refraction, care mami 
he exereised to emerging from the prism are a 
wht angles to those incident to it, and that the areas of the squart 
faces of the prisin are sutticiently large to have inscribed withia 
them a circle equal to the back lens of any condenser used. 


Nome employ w been known asa Chite cloud dams 
that a plaster of P: or opal glass with a poli 
surface. Buta dise of finely ground glass s dropped into the diap! 


holder of the condenser will give a precisely similar result. 
ver, pointed out the curious fact that ax 
it mirror becomes an inexpensive and excellent substitabe 
sing prisun, 

Typical Modern Microscopes.—We are now ina position tocare- 
inspect the characteristics of the chief forms of microscope 
which the modern manufacturers of England, the Continent, 
America offer to the microscopist. 









































A TYPICAL MODERN STAND 173 





Frio. 129.—Powell and Lealand’s No, 1 stand. 


means of a milled head most conveniently placed, and the» a 
ircle i plate of silver! Tr will also rapidly rotate by han 
graces re, oes © Cee 
48! al as we have already indicated, | 
< EeS Tent acl to the use of a longer lever for the ihe adjust- 
ment (p, 161). The milled head is placed behind the strong pivot 
of the arm, where vibration is impossible, and it isin an easy and 
oer Leap cnr a ith Gt cheats eed 
e mA t ease, enti the arm; 
this rnkea the pane iis icccnlar Ge sou teller Roce O a short 
or long body « matter of choice, while it yives access for cleaning and 
other purposes to the nose-piece tube, as well as for the insertion 
and focaming of the lens used with an apertometer,® or an anal: 
prism. So it is of service in low-power Bote eS 

We have already referred to the stage of this in nt 5 
‘but it may be briefly stated that it is large, has complete rotation, 
it has one inch of rectangular motion, Being graduated to the y)qth 
inch for a finder, There is the seme speed in the vertical and the 
lateral movements, and the pinions do not alter their positions. The 
aperture of the stage is sats large, 

The ledge of the stage has a stop placed on its left-hand 
side; this is held by « screw, but 1s removable at pleasure, 
Two massive brackets under the stage remove all possibility of 

neure, 

The sub-stage has rectangular movements by screw in either direc- 
tion, as well as a rotary movement by pinion. The coarse adjust- 
ment is by rack-work, and a fine adjustment is ndded when desired. 

1 ‘Thin ix now made of platinum if desitwd, and thas tarnish is obviated, 
* Chapter ¥. p, 887, 








176 THE HISTORY AND EVOLUTION OF THE MICROSCO| 


1. The distance between the centres of the eyes. 
2. The mechanical tube-length. 
In order that the binocular may suit persons with ‘a 








= 


17% THE HISTORY AND EVOLUTION OF THE MICROSCOPE 
anes nn fei wrt nr finish; 


was forthe wos bing taco on igen 
not sufficiently extended, enaitbie tinder part of the foot was too 
large, so that it sometimes rocked fot plata beoatinn ik hinder 


jnently used by various makers now, and is known ag the ‘ bent claw.” 
ae te been, easily thrown over 

The i introduction of the Jackson’ limb brought its inevitable 
troubles—notably, with the fine adjustment—to which we have fully 
referred under that head, But in the Ross-Jackson model the fine- 
adjustment screw was placed behind the be (as the figure shows), 
which was an improvement; still the body and the coarse adjustment 
were both carried by the finé-adjostment lever and screw, 

‘This form pay! not—as it did not—long prevail. Its existeace 
was ephemeral, and in its place was put a modification of the form 
devised by Zentmayer, known abeedoontly tly as the Ross-Zentmayer 
model. This was the Ross-Jackson instrament with a ‘swingi 

sub-stage.' This instrament is illustrated in fig, 133, It ai be 
seen that the foot is a true tripod, consisting of « triangular base 
with two pillars rising from a cross-picoe, which carried the trun- 


nions. 

We have alneudly assessed the value of a swinging sub-stage, and 
found that in our at ee it is at best redundant.! Now: 
is complete without a good condenser, all, and much more than all 
that can be done by a swinging sub-stage can be done with aslotted 
stop at the back ofthe condenser, This elaborate appendage eliean 
fore without justification, Yet in the impatience he large ilh 
nating apertures, ihich were not at that time provided by Saal 
this phase of illumination was carried to a still greater and more 
elaborate development in the production of a concentric microscope, 
‘This was a Ross-Wenham, known as the radial microscope. 

In the early days of this instrument, when no achromatic 
condenser exceeding 170° in air was to be obtained, in some very 
difficult researches needing all the great advantages that come 
from great aperture, the present Editor was able, with much 
labour, to get results with this instrament not otherwise attain- 

1 P. 100 et tog. 





SUE Aiy 







brit Dosiutertaad: 
se 
wiit dtu 







180 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


able, but which were none the less almost counterbalanced by the 
deficiency of its fine adjustment, Nevertheless since the advent of 
achromatic and apochromatic condensers with oil contact all this is 





Fro, 184. 





Fro. 185. 


‘The optic axis of this instrument is capable of being rotated in 
three planes at right angles to one another with the object as a 
centre, and in addition to this it has a swinging sub-stage. This 





Frio. 136, 


will be seen and w 
from the illustrations given in 
figs, 134-137, 

Concerning the fine adjust- 
inent of this as « Jackson model 
primarily we have already 
written. 

Another leading form of the 
firwt class is the No. 1 of Messrs. 
R. and J, Beck, The early an- 
cestor of it was shown on page 
154, but it has undergone im- 
portant changes as it is now 

resented (fig. 138). It is a 
lackson model, the foot being a 


) good tripod, and the trunnions 


on pillars (as fig, 138 illus- 


_ trates), Tt has a short lever 


fine adjustment, 1, acting on a 
movable nose-piece, and placed 
in front of th 





Lody and coarse adjustment are carried by the fine-adjustment screw, 


‘The stage has a rotation, bat not complete, 





he stage aperture is 


not so large as it should be; on a pivot attached to the limb the 










rot rs Sh ell et 






a 
Ord ore OMI Hpadnatiw rei 
boas mA 1 


» to ale 





























Fie, 194—R. and J, Beck's No, 1 stand. 





tito ha a ey 
Peep nh diner 





Fro. 199.—Zentmayer's microscope. 


184 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


Set Ch sptbtst spring which ppeieleterers ees by. Leaps 
a Re wl ‘at wi screws, 86 

Bei nsteeyn ot ts cobra ot tia sab stage, ‘Tt is not the best form 
for so ‘a part of the instrument, 

All the movable parts of Swift's instruments are sprung on Powell 
‘and Lealand’s method, and the movements are smooth and sound. 

There have been man} stands devieed ty eee 
during the past twelve or pep ee have been based: 
y FE CAT eran ee oe the modifications, 
whether for Beer been adopted into the recent modifi- 
cations of eee Sree Send soe 
described, It should be remembered that Zentmayer, of Philadelphia, 
devised the model from which the Ross-Zen' was finally 
Its ty hesringng sage obtain oblique illumination in one azimuth 

‘The fine adjustment of this instrument was 
kif aefctve. again, who wholly deserves the very teh 
reputation he taba made an instrument in which he mount 
Heart al ‘on a disc, as is now the case with the Beck rodel (ig 130), 

edge of this dise the sub-stage is made Goebel Bo vi 
carrying the condenser, or dry combination, in an are round the 
object asa centre, This was only another elaboration of the same 
swinging sub-stage. 

In later constructions of this form, Tolles first used the mechanical 

actuated by two pinions vertical to the surface of the stage, 
an subsequently aday by Ross (fig. 128). The fine adjustment 
in this instrument the fatal defects characteristic of its form. 

Bulloch, another American maker of note, made some modifica 
tions in the EAN model be they dates in the interests of the 
swinging sub-stage, ang h no doubt ingenious, must 
orient transient form of the aceon. pat? 

An illustration of the leading form Of Zentmayer's microscopes 
ig seen in fig. 139, 

Tt will be noted that, as in the case of the Ross form of it (fig. 
133) its chief characteristic—no longer, if ever, a merit—is its swing- 
ing sub-stage. But this has the claim of being the first modern in- 
strument to respond to the cry for swinging sub-stage, and certainly 
no better response has subsequently been made, 

In the stage on the complete instrument is the ingenious ar- 
mangsoen of a glass super-stage, which has been so freely adopted 
in England on a certain class of instrument, and, in the absence of 
a complete mechanical stage, is the only substitute to be tolerated, 

But another stage was made with this instrument, shown in fig. 
140, with, however, some modifications in detail. Thisis not distinct 
from English forms of stage of long standing. 

A modification of this stand was devised by Bulloch, seen in 
fig. 141. It presents no ‘ial point, save the employment of a 
Gillett ication with the fophrogra dram above the lenses | 

A later development of this form of instrument is given by the 
same maker some years later, and shown in fig. 1425 but the rehiek 
difference consists in the adoption of a stage in which the milled 
heads stand npon the etage, which is the reverse of an advance, 


WALES TRAVERSING ARC FOR LIMB 185 


An instrument made by Bausch and Lomb, and known as thei 
professional microscope, is illustrated in fig. 143, Ie eon the ate 


i 

each other, or sim hen the th 
rey i rmipeneoien ly aay 
claimed for this form is a ‘frictionless fine adjust- 

bat it is one of the many which have the intolerable burden 


al ijrtment oft of the Enea ene ie delicate 
mw 1 3 ou i ingeniot 
to our mind, wl imperfect for halen view ims 


is 
Mr. George Wale, of vised a plan of some merit for 
certain classes of microscopes. The ‘limb’ which carries the body 
and the instead of swung by pivota—as ordinarily—on 
(so the balance of the microscope is 
inclined), has a circular groove cut 





i 
i 
i 






Fro, 140.—Zentmayer's stage. 


‘on cither side, into which fits a circular ridge cast on the inner side 
of each support, as shown in fig, 144, The twosupports, each having 
fore-foot, are cast Jae {in iron), 80 as to meet to form 

they ure held together by a strong pin ; while 

by turning the milled head on the right support the two are drawn 
t by a screw, which thus regulates the ire made by the 

‘that work into the two grooves on the limb, When this 

ni can be more satisfactory than either 
smoothness of the movement or the balancing of the 
instrument in all positions ; while, by a slight tightening of the 
screw, it can be firmly fixed either horizontally, vertically, or at any 
inclination. The ‘coarse’ adjustment is made by a smooth-working 
tack ; but the fine adjustment is made to carry the whole weight of 


1 














Fra, 142.—Bulloch’s new Congress stand. 


us 
188 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


rotation is without a rack-and-pinion movement while stand 
and stage shaper But in the eed instants tue beysabe ie 





Fio. 143,—Bausch and Lomb's professional stand. 


SECOND-CLASS STANDS 189 


the same length, and reeeive the same objectives and sub-stage 
fittings as No. 1, oer ¥ 

As a model we prefer Beck's ‘ small first-class? stand to their | 
instrument. It has an excellent single pillar tripod foot, ‘Turrell’s 
arrangement of milled heads (like Powell and Lealand’s stands) for 





Fic. 144,—Mr. George Wale's instrament with new form of limb, 


‘the mechanical movements of the stage, and rectangular movements 
for the sub-stage. This is a fine instrument, and would be admirable 
iNet way with a more perfect fine adjustment. Powell and 
's second-class inatrinment is, in oll essential particulars, butlt 

upon aes their No. 1 stand, though less elaborate, 
Tn of the second class there is by no means so great 


a 


inemenae dears viptel sd 


to 
quality of work not second their large r 
a it not even to thei) 
second-class instrument. Tt is illu in fig. 145. 
‘The tube length is the same, but the stage and the foot are smaller 
than in the second-class instrament, ‘There is no rotary movement 
to the sub-stage, and its centring is done by the ing of sectors 
and not lines at right angles ; but this is in no way a All 
the movements and adjustments are otherwise as in No, 1. 
As a rule, third-class ape ee E aeeare rm stages ; 
in this respect Powell and 's is an important exception, 
because it has a stage provided with the most perfect mechanism that 


F 


can be employed. 

Beck's third-class mi is shown in fig. 146. Tt has a good 
flat tripod foot with a single The Jackson model is used, but’ 
4 peculiar fine adjustment is em Ni apalesee, Raatts ete 
the stage, the screw bein immediately behind evel ee 
spo eo ee it is easy of access, The body is not 
affected by vibration when it is touched. 


The lever is of the second order, and it supports the body limb 
and coarse adjustment. In fact, save in its fine adjustment, this 
form approximates somewhat to the Continental morel, The fine- 
adjustment lever is rather short, but it will be found to be steadier 
and slower than the direct-acting screw. 

‘The stage is plain, without mechanical movements ; but it has a 
movable glass stage over the principal stage ; to this the slip is 
clipped and the whole super-stage of glass is moved with much ¢ase 
over a fnir urea. The aperture in the glass stage is not la 
enough ; it should be cut right through to the front, which would 
much increase its usefulness. 

This instrument also has a sub-stage with rack and centring 
movements, 

Swift and Son's third-class microscope in its most suitable form 
dates from about the time of the vertical lever fine adjustwent 

tented by that firm. It was first made from the designs of Mr. 
. M. Nelson, and it presented three distinctive features :-— 

@) The milled head of the fine adjustment was placed on the 
left-hand side of the limb. n 

(2) The stage was of a horse-shoe form, the aperture being 
entirely cut out to the front of the stage ; and wy 

(3) The body-tube, which was of standard size, ‘viz. af inches 
was made in two pieces which not only secured portability, but also 
permitted the use of both long and short tubes. 

‘This instrument is illustrated in fig. 126. It was also possessed 
of a cheaply made and fairly good centring sub-stage, to carry 
Powell at Jand's dry achromatic combination fitted with aturn- 





THIRD-CLASS STANDS 1g! 


out rotary arm tocarry stops. The sub-stage was made adaptin, 

Swift's centring nose-piece, and providing it with a Se ae 
focussing arrangement, as illustrated in 147. There was also a 
graduated stage-plate and sliding bar, a ‘devisetl by Mr. Lewis 





Fie, 145, 


Wright for a finder. The eye-pieces were provided with rings, like 
Powell and Lealand's, outside the tube to govern the depth which 
each should slide into the draw-tube, by which means the diaphragm 
is in the same place whatever the depth of the eye-piece employed, 















194 THE HISTORY AND EVOLUTION OF THE MICROSC 


tion, When horizontal the optic axis is 8} inches from the 
The ends of the feet are plugged with cork. 

It proved on testing that the Campbell differential s 
equal to the most critical work, and could be used in ph 
graphy. As a result several additions were made, such as 
pinion focussing and rectangular movements to the sub-si 
rack-work arrangement to the draw-tube. Subsequentl; 
and heavier instrument was made, haying a }-inch more of 
he In this model the milled head of the ditferential 
od below the arm, instead of above it, which is an 
for photo-micrographic purposes, and no special detrimentia & 
work ; and, if required, a differential-screw fine adjustment 
fitted to the sub-stage. A rotary stage is also sometimes 
this instrument, but those which we have seen have not givelll 
:perture sufficient dimensions for modern focussing. 

This instrument in its complete form as devised by 
shown in fig. 149. The stage has changed its form ; but if 
aperture he kept large enough this may be: fully counterbalani 
the rotation given to it, and with the Campbell screw fitted } 
the mirror for the fine adjustment of the condenser is a very a 
tive and useful microscope, and may be safely recommended ta 
amateur and the student. 

There is not sufficient rack-work 
Zeiss, but the nose-piece un 
the tube by an a 




















































to focus the 70 mm. ob 
and the objective is held i 






BW 













of the third class bec 
but a supplementar 
Mr. John Mayall 


use it is unprovided with a mechani 

y and removable mechanic: devised 

id made by Bake my and Swift, a 

of Jena, can easily be added, as it is in the figure (149). 

fairly well, and is « useful appendage for more delicate stage wi 
Fourth-class Microscopes.—These should haye a r; 

course adjustment und a direct-acting differential_screw 











INEXPENSIVE MICROSCOPES: 197 


stage is fastened to the v side of two brackets which 
one per with the limb ; arte under side of ‘een brnckars 
is plate which holds the sub-stage tube, 

instrument is supplied with lat ‘and concave mirrors ; 
and soos pee eairin 58 class of 
very m its favour as a secondary instrument for the work-tabl 
Like all these makers’ instruments the feet are oaaed So GES 


ogee 





Fig. 151.—Swilft’s fourth-class microscope. 


| eens Some of these microscopes that, have been in use 


| years, ancl are still the trusted ‘journeymen’ instruments 


Pepa and other workers of various orders in many depart- 
meine Messrs Mens sk ove make « Jalocosions of this kind called a 


Tt is illustrated in fig. 152; the 
ene a “loops” Or simple lenses can be used instead. 





198 THE MWISTORY AND EVOLUTION OF THE MICROSCOPE 


dhe Eady dows ck facia; ut ta: pli yl ay eet 
loes not incl it in it} an in- 
strument of this class it deserves comm oe ps 

Portable that may be readily taken 


eed jeroscopes 
from place to which are meth provided with the arrange- 
ments requi pegany the pri es yee us, are of ing 
in some investigations, and are Piel the majority of those who 
have a living interest in microscopic w 

The earliest, and still the best Bul} Bi this kind of microscope 
was made by Powell and Lealand. As opened for use it is illustrated 
in fig. tba; but the tripod foot 
ioc into what becomes practically 

le bar, and is bent by means 

a joint to occupy the least space. 
‘The body unserews, and the whole 
lies in a very small apace, giving 
at the same time fittings in the 
cabinet for lenses, condensers, and 
all needful apparatus. The coarse 
and fine adjustments to the body 
are asin the No, 1 stand, so are the 
stage movements ; and thesub-stage: 





Fro, 152—Beck's histological and dissecting microscope. 


has rack-and-pinion movements and rectangular sector centring, 
while all the apparatus provided with the largest instrument can be 
employed with it, We have used this instrument for delicate and 
critical work for fifteen years and there is no falling off in its quality ; 
and when packed with the additional apparatus required the case is 
12 x 7 x 3 inches, 

Swift and Son subsequently made an instrument on similar lines. 
The cae and stage are packed practically as was Powell and Lea- 
land’s, but the stage in this case is plaiti. It carries a very con- 
venient achromatic condenser, to which we call attention in its proper 











200 THE HISTORY AND EVOLUTION OF THE MICROSCO] 











from the two preceding forms in being a Jackson model. 
ocular body and the coarse adjustment have to be lifted and 
by the fine adjustment whenever it is used. The stage is plain lke =. 
rotates, and the sub-stage has no centring gear. The i 
packs into a box 10} x 74 x 34 inches. There is a 
specially made for this instrument. 

Mr. Rousselet has designed an admirable little instrument of 
able form but of the sixth class. It is binocular. The tripod 
the stage is plain, with a sliding ledge. The condenser 





DISSECTING MICROSCOPES 20L 


use with compound lenses has been devised by employing the bin- 
ocular of Mr, Stephenson. This instrument is illustrated in fig. 157. 
Tt is made by Swift and Son. The stage is « large, flat table, with 
special rests for the arms. The objective and binocular part of the 
jody remain vertical and focus vertically by a rack-and-pinion 
Coarss adjustment, there being no fine adjustment. The Bodies 
above the binocular prisms are suitably inclined, mirrors being placed 
inside them to reflect the image. jis reflexion also causes the 
erection of the image, which is valuable to the majority engaged in 
vera dissection or the dissection of very delicate and minute organ- 
or 

We have now to consider the most primitive stands adopted for 

simple microscopes. That in thé form of a bull's eye stand is the 





least complex form possible, This instrument holds an intermediate 
lace between the hand-mngnifier and the complete microscope, 
in fact, nothing more than a lens supported in such 4 manner 

be capable to being readily fixed in a variety of positions 
for dissecting and for other manipulations, It consists of « 
circular brass foot, wherein is screwed a short tubular pillar (fig. 158), 
which is ‘sprung’ at its upper end, so as to grasp a second tube, 
also * ) by the drawing out of which the Pillar may be elon- 
gated by about three inches, This carries at its upper end a jointed 
which « square bar about 3} inches long slides rather 

5 and one end of this bar carries another joint, to which is 
tring for holding the lenses. By lengthening or shortening 

the ates by varying the angle which the square bar makes with its 
n by sliding that bar through the socket, almost any posi- 


& - 
5 


: 


i 


| 











— 


204 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


Quekett, which has superior advantages. In the form illustrated 
we are obliged to mechanically the horizontality of the lens, 
which, of course, is important, In Quekett’s form the lonp or lens. 
is so hung in a that 
ithasa julous motion, 
a and with every Shanes in 
the position or angle of 
the bar, the lens, by the 
ion of (sed becomes 
perfectly horizontal. This 
18 by far the best form of 
mounting. Although the 
uses of this little instru- 
ment are greatly limited 
hy its want of stage, mir- 
ror, &e. yet, for the class 
of purposes to which it i* 
suited, it has advantages 
over perhaps every other 
form that has been de- 
vised. Where, on the 
other hand, portabili 
may be altogether sacri- 
ficed, and the instrament 
is to be adapted to the 
making of large dissec 
tions under a low magni- 
fying power, some such 
form as is represented in. 
fig. 159—constructed 
Messrs. Baker on the basis 
of thatdevised byProfessor 
Huxley for the use of his 
Practical Class at South 
Kensington — will be 
found decidedly prefer. 
able. The framework of 
the instrument is solidly 





constructed in mi ys 
all its surfaces heing 
Fio, 158, blackened, and is so ar- 


ranged as to give two w 
rights for the support of the stage and two oblique rests for the 
hands, Close to the summit of each of these uprights is a groove 
into which the stage-plate slides ; and this may be either a square 
of moderately thick glass or a plate of ebonite having a central 
perforation into which a disc of the same material may be fitted, 
80 as to lic flush with its surface, one of those being readily 








208 THE HISTORY AND EVOLUTION OF THE aNCROScOPE 


relation to the optical poi instrument . 
ing ape tay en ven siti ee ee c 


peer rack-and-pinion Preterm sted “which 
caves the horizontal rn for he supp of the Ins r 
Sieg ahich ORL HY ix ths cppeata Aastha, hea Boa age 
wi in 
over the centre of the staye-aperture. Beneath this aperture 


is a concave mirror, which, when in use, lies in a recess in the 
mahogany base, 80 a8 to leave the pc i oe tis 





a 
Hae 
83 


free to receive a box containing 4 ; whilst from the 

hand back corner there ean be a stem carrying a side condens- 
ing lens, with a ball-and-socket movement. In addition to the: bes oct 
Tenses and pecs ae combinations iste Reon for eat gg erels 
dissection, a ae on 
the principle ‘ie bifocals ‘Nachet, about ed same date, in their 
shereo-pseudoscapic Mr. Wenham’s method 
of allowing half the erie rays to to one eye without inter- 
ruption, he caused the other to be ct bya of 
prisms, and to be by them Dapaiecee pa the other eye. But we 
tind its utility to be EY rae rte pyithe ee eenice oe 
field of view, by its defi pegs it and of ma 

by the inconvenience of the manner in which t! afer ave to a 


applied to it, 

‘The Continental Model..Our one pu in this treatise is to 
endeavour to promote what we believe to be the highest interests of 
the microscope as a mechanical and optical instrument, as well as 
to further its application to the ever-widening area of physical 
inv ition to which, in research, it may be directed. To this end 
throughout the volume, and especially on the subject of the value 
and efficiency of apparatus and instruments, we have not hesitated 
to state definitely ou our judgment, and, where needed, the basis on 
which it rests. Incidentally we have expressed perhaps more than 
once our ¢ixg, 1, and with ourselves that of many of the leading 
English and a Asan mnicroscopists, of the form of microscope known 
as the Continental model ; aie cherish strong hopes in the in- 
‘terests of the science of microscopy that so enterprising and eminent 
a firm as that of Zeiss, of Jena, will bring out a model that will 
comport more completely with the needs of modern miei ‘ical 
research than even the best of the models that they now luce. 
Tt is to this house, under the cultivated guidance of Dr. Abbe, that 
we are indebted for the splendid perfection to which the optical side 
of the microscope has been recently brought; and when we know 
that the ‘Continental model’ has in the hands of the firm of Zeiss 

from an instrument without inclination of the body into an 
instrument that does so incline, and from an instrument without 
sub-stage or condenser into one provided with the latter of these abso- 
Tutely indispensable appendages, and finally from an instrament with 
a perfectly plain stage with ‘clips’ into what is nowa stage with me- 
chanical movements—we can but Wei that these concessions to what 
thas belonged to the best English models for over forty years may lead 


210 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


observations of a histological charter (und therefore of a nature to 
lie beyond the sphere of the lay amateur) had been successfully made 

with a certain form of microscope 
on the Continent, it was practi- 
cally argued that this must be 
the most suitable instrument for 
such a purpose ; but this was an 
inference made without know- 
ledge of or reference to the well- 
known English models, 

Let us carefully examine this 
instrument. The typical form 
was that made by wit a 
Seen in its best primitive state, 
we have it in one of Zeiss’ in- 
struments represented in fig. 162, 
Tt is a non-inelining instrument 
with a short tube on a narrow 
horse-shoe foot, in which steadi+ 
ness is obtained by sheer weight. 
It has a sliding tube as 4 coarse 
adjustment, and a direct-acting 
serew for the fine adjustment. 
The stage is small, and the aper- 
ture in itisrelatively still enelie 5 
of no service in reaching the focus 
of an object by to with 
high power. It is provided with 
spring clips, and a diaphragm im- 
mediately below the stage, and « 
concave inirror, 

A aub-stage condenser was 
rarely used, because up to a com 
paratively late date (1874) it was. 
regarded by many on the Con- 
tinent as a mere elegant play- 
thing; its true value was not 
perceived, 

On this model all the miero- 
scopes of the firm of Zeiss, of 
Jena, are constructed, as they 
are used almost exclusively on 
the Continent, and are regarded 
in many of the universities and 
medical schools, both here and 
in America, as possessing all the 
qualities required for the best 
biological research. 

If we examine the finest of 
these instruments made up to 
1885, we are impressed, as we 











212 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


and objective fronts ; and we have reason to know 
ce ‘a few are with this form of stage; but we have 


2. The rotation of a microscope object for ordinary examination 
really unimportant, as there can be no top or bottom toit, Even 
tora jue illumination it is not required, as as it is al easier to 
te the illuminating pencil. The only instances in rotation 
Stthe object fe important are z (a) When the object ix polarised, and 
then it is a fiver tee nets a nob abe mulede aber abchars ri 
ii ently 6 wi carries the J 
sng talig independant ot the body would be preferable because, 
it is required to rotate object on a dark polarised field, the 
polarising and analysing Le 2 ae can be set at the angles, and 
then the object rotated without disturbing the relative positions of 
the prisms. 
ut this cannot be done with the arrangement of the Zeiss sony 
which ae body and stage. er Pic 
(B) -micrographic purposes.—In this ease in 
me Niet Todi ofthe fine-adjustment screw is geared to the focussing 
vod: 80, manifestly, rotation of the body becomes impossible. 
Thus, b adopting rotation in the form chosen, the highest ends 
for which the microscope stage should revolve cannot be 
The sub-stage is often quite wanting in the common Continental 
forms, This was true of the Hartnack stands, with rare exceptions ; 
the Nachet instruments were provided with an element hice en 
As we ave rae until quite ares arr ye) 
regarded on the Continent aa as ions, if not a li applies 
but that prejudice has been ‘ae the light thrown on the whole 
question bya) the chromatic (1873), an now (2) the achromatic 
cnteaer ot Ab be, But even a compownd condenser was in use in 
England in the year 1691, and the best work in England since the 
inyention of achiomatism arches been done without one. ay 
In the. mounting of the condenser every possible ingen: 
has been displayed to make it do its work without a sub-stage ; but 
a pietae ai and focussing sub-stage into which this optical 
rangement could, amongst others, fit, might be made for the 
5 ingenuity, and cost. But rather this,we have the con~ 














216 THE HISTORY AND EVOLUTION OF THE MICROSCO 


screw fine adjustment, a plain stage, and an elem 
centring nub-stage, Such an instrument should be obteia 
. 108. 

Although not frequently used, it would be doing our wa 
perfectly not to rele to 2 special form of miaroscope devi 
chemical This is an tnverted microscope original 
structed by MM. Nachet on the plan devised by Dr. J. La 
Smith, of Louisiana, U.S.A., for the purpose of viewing objed 
their under side when heat or reagents are being | lied to 
has lately been improved by its constructor with a special 








7” 


218 THE HISTORY AND EVOLUTION OF ‘THE MICROSCOPE 


erystals be studied lie in their natural position 
Seen ee nreeraene 


thas Ut itis valoabloitn thalegemiveticn 6fdlateiraiseen 
and other objects in water which are heavier than it, and therefore 
sink to the bottom; also in the moist histological preparations, aa 





F10, 106,—Tho same instrament changed into an ordinary forme 


they adhere to the surface of the slide, and are therefore in one 
plane. It is also an excellent dissecting microscope, as it is partially 
erecting, offers no hindrance to manipulation with any power, and 
makes it convenient to observe the object directly. ere are two. 
forms, the ‘Laboratory’ and the ‘University.’ The Laboratory 
microscope, when used asan inverted instrument, is shown in fig. 165, 





220 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


certain kinds of work, a value of their own. They may be 
with low powers outside the glass or above the water; or 


ol may be protected by a water-tight tube outside it 
Sr pea et phere, into that end 


eiel 


i 
af 
a 


Es 


aquarium, as shown in 
the woodcut (fig. 169). 
To adjust it to ria 
of different wi the 


be clamped at any 
given point by the 
upper milled head, The 
milled head at the 
side, by pressing on « 
loose plate, fastens the 
bar securely to the 
aquarium, 

Between the ends 
of the bar slides an 
arm carrying a 

Fi. 108. poke ainlh ie aaa 

‘The * University * microscope fixed for upright use. gan be clamped at any 

. given point of the bar. 

Through the socket is passed a glass cylinder, cemented to m brass 

collar at the upper end, and closed at the lower by a piece of cover- 

glass, Into this cylinder is screwed the body-tube of the cinoma 
with eye-piece and objective, which are thus protected from 

water of the aquarium. The microscope is focussed by rack and 








j 


222 THE HISTORY AND EVOLUTION OF THE MICROSCOPE 


an indiarubber ring surrounding a central The ring is 
to the glass surface of the ‘ium, the air piper! 
round the head of the piston seen on the ‘Two turns: 
are sufficient to fasten:the sucker securely. The to which the 
s of the body-tube is attached passes through the sucker-arm, 
can be ela at any height desired, 

Professor E. Schultze has designed and Messrs. Klénne and Miller 
have made the microscope, fig. 172, for the observation of small aqua- 
tic organisms in an aquarium ey constructed for the purpose. 
There are three parts: (1) the stan shia peatee of which is 
nickel-plated ; (2) the aquarium ; (3) the illuminating mirror, 





Fro. 170, 


‘The stand consists essentially of a microscope-tube, which is 
supported in a horizontal position Sse a tripod in such a way that 
it can be moved in three different dir ons by rack and pinion. 
The column of the tripod carries a rack and pinion, by which the 
tube is moved vertically. On ube which carries the rack is slid- 
ing piece with a second rack for the horizontal movement from right 
to left ; upon this slide the microscope is fixed in a horizontal posi- 
tion, and can be moved backwards and forwards in a tube provided 
with rack and pinion. There are therefore three movements—verti- 
cal, horizontal-lateral, and horizontal-sagittal—so that the organism 













224 THE HISTORY AND EVOLUTION OF THE MICROSOO 


The mirror is concave, 10 cm. in diameter, and fixed up 
stand with a ball-and-socket joint so that it can be adjusted 
position, 

As an adjunct, and admirable aid to the student of the t 
pond, as well as a simple and easy means by which specific 
microscopic life may be be found and readily taken, we call al 
to the tank microscope of Mr. C. Rousselet. It is illus e 
173 and scarcely needs further description. 

One.of Zeiss's Steinheil ‘loups’ or aplanatie lenses, to whi 
have referred, is carried on a jointed arm, which is clamped 
tank,' the tank being nowhere deeper than the range of 
the lens employed. ‘The arm moves on a plane parallel to # 







AQUARIUM MICROSCOPES 225 
It so frequently happens that a minute object is lost simply by 


removing the pocket lens for an instant to take up the pipette ; 





it in the required posi Fic. 173 —Ronaselet’s aquarium microscope. 
(Se. 174). object 

ving been fixed in its place, and the conrse adjustment mude by 

sliding the body in the outer tube, these parts inay then be immov- 

x being left movable except the eye-tube, by 

i which in or out the fine adjustment may be effected. Thus 





Fro. 174. 


the whole tus may be passed from hand to hand with the 
greatest faclhty, and without any probability of disarrangement, 
and every observer may readily ‘ focus” for himself, without any risk 
of injuring the object, 





CHAPTER IV 
ACCESSORY APPARATUS 


on apparatus accessory to the microscope might be 
SET Eats ean eaabes Pets Game nee OE 
the entire remainder of the book ; the ingenuity of suecessive aicro- 
scopists and the variety of conditions presented by successive improve- 
ae the microscope itself have given origin to such a varioty 


identally : 

planted, or which present modifications either not important in them- 

selves, or accounted for by the fact of their production by different 
‘ians. 


I. Micrometers and Methods of measuring minute Objects.—It 
is of the utmost im nce to be able with accuracy, and as much 
simplicity as possible, to measure the objects or parts of objects that 
are visible to us through the microscope. 

The simplest mode of doing this is to project the magnified 
image of the object hy any of the methods described under ‘Camera 
Lucida and Drawing! (p. 233). [f we carefully trace an outline 
of the image, and then, without disturbing any of the arrangements, 
remove the object from the stage, and lace it with a ‘si mi- 
erometer,’ which is simply ete thin glass ruled to any desired 
seale, such as tenths, hundredths, thousandths of an inch and up- 
wards, ‘Trace now the proj image of this upon the same paper, 
and the means are at once before us for making a comparison between 
the object and a known sxeale, both being magnitied to the same ex- 
tent, The amount of magnitication in no way affects the problem. 
Thus, if the drawn picture of a certain object exactly fills the in- 
terval between the drawing representing the -01 inch, the object 
measures the *01 inch, and whether we are employing a magnifying 
power of a hundred or a thousand diameters is nota factor that 
‘enters into our determination of the size of the object. In fact, all 
drawings of microscopic objects are rendered much more practically 
valuable by having the magnified scale placed beneath them, so that 
measurements may at any time be made. 

In favour of the above method of micro-measurement, it will be 
noted (1) that no extra apparatus is required, (2) that it is extremely 
simple, and (3) that it is accurate. 

The most efficient piece of apparatus for micro-measurement is 



















228 ACCESSORY APPARATUS 


employed is high, in order to effect the of the great i 
tiok, he wire *ithe fixed central one) will be in the mi 
field, the other at the ‘in, and the cumparison will not} 
on account of the unequal magnification of the eye-pé 
out the field, whereas if the wire be placed five notches on 
both measurements are brought more within the centre of 
Messrs. Zeiss now make a Ramsden micrometer i 
provided with a glass plate with crossed lines, which 
the eye-piece are carried across the image formed by the 


Fro. 176. 


by means of the measuring screw, so that the adjustment a 


| 





the micrometer eye-piece is |, as it usually has been, in the body- 
tube of the microscope. The consequence is that much more minute 
mace can be measured, and with much greater accuracy. Mr. 

elson has repeatedly ned the yggyth of an inch by means 
of a stage micrometer in the focus of the objective: this was replaced 
bya mourited specimen of Amphipleura pellucida, and he has counted 
ninety-six lines in the rgooth of an inch hy making the movable wire: 

t 


pass successively over them until the fixed wire was reached, 
similar means the Editor has measured single objects less than the 
leeoth of an inch. 

It will have been premised by the careful reader that the stage 
micrometer must be used in every set of measurements ; at least we 
would strictly emphasise this as the only accurate and scientific 
method. It has been advised that a record of comparisons with the 
various lénses in the possession of the eres should be made 
once for all. We decidedly deprecate this method, unless it be in 
such utterly valueless work, as is sometimes done, where lenses are 
uncorrected and accuracy of tube-length forgotten or ignored. The 
correction of an objective and the tube-length ought to vary with 
every object, and therefore a comparison of the stage-micnometer 
and the serew-micrometer should be made with every set of measures 
ments. 

Moreover, the majority of stage micrometers exhibit. very eon- 
siderable ‘discrepancies in the several intervals between the lines ; 
it is well in the interests of accuracy to take the serew value of each 
under a high power, find the value of the average, and then note the 
particular space or spaces that may be in agreement with the average 
and always use it, An illustration will make this clear. 





\AIN THE VALUE OF A MICROMETER INTERVAL 231. 


provides a stage micrometer of 1 mm, divided into +1 and 
‘allowing are the actual values obtained for each of the “0B 
fence’ 

840 

8:37 

8:38 

8:38 

8:36 

8:36 

8-58 

38 

8-31 

847 

833. 


#9 ORS 
29/1676) ~ 
8-38 mean value. 
istance it will be seen that the last division, 8:38, agrees 
mean, and is the best for all future use.’ 
ig thus obtained a screw-micrometer value for a certain 
iterval, the screw-micrometer value for any other object 
swn, the size of the object may be found by simple propor- 
1s, viz. if 8-38 is the screw-micrometer value for ‘05 mm. 
that for a certain object, the size of the object is 
(i) 8-38 : ote te 2% :2mm.; 
45x 05 
2=- y= 0385 mm, 

answer is required in fractions of an English inch, all that 
semember is that 1 inch = 25°: 





2 stage-micrometer is ruled in fractions of English inches, 
pose the screw-micrometer value for zlygth inch = 4-257, 


for the object = 6°45 as before. 
(iii) 4-257 : 6°45 :: O01 : x inch ; 
— 6°45 x 001 _ es 
427 => 001515 inch. 


1 womber given for screw value the whole number stands for 8 complete 
se number of revolutions of the screw-head, and the decimal, the portion 
thom read off beyond this. 


232 ACCESSORY APPARATUS: 


Setheananet s required in metrical measurement, then as 1 
inch = 
(iv) $257 2 645 2: (001 x 25-4) : aemm. 5 
om O85 004 1638 ge8 . 
Tn this connection it will be as well Sete two 


scale which are sometimes req: Thus 
eit cate aces yes 
be accurate, and you wish to compare 

swith thiretale in ondor ta Bd ont which, falar eae 


tied epenten Suppose 05 mm. = 8:38 serew value ax ie 
is to find the point to which the screw 
micrometer must be set in order that it may accurately span the 
quo inch, Take 1 inch = 25:4 mm. as before ; hen 001 ineh==-0954, 
(vy) ‘05mm. : 0254 mm, 2: 8°38 ¢ x screw value 5 
c= ‘ORE XBSS 4257 screw value, 

Conversely, if @ metrical seale is to be compared with an accurate 
English one where ‘001 inch = 4:257 screw value, then the screw 
value for °0 mm, may be found thus : ‘001 inch = 0254 mm, 

(vi) °02541nm. : 05mm. :: 4°257 : w screw value ; 


“05 x 4257 _ “ 
o= <DI5E — = 888 screw value for 05 mm. 


A cheap substitute for the screw-micrometer has been devised by 
Mr. G. Jackson, It consists in having a transparent arbitrary 
inserted into an ordinary Huyghenian eye-piece in the focus of the 

eye-lens, so that it 
A will be ae same 
plane as ee tm 
fied image of the 
object to be mea- 
sured. It is seen in 
fig. 178. The method 
using it is precisel; 
aieete that of the 
screw micrometer; the 
value of yyy inch or 
alg mm., as the case 
may be, is found in 
terms of the arbitrary 
scale. The value of 
the object in terms of 
the same scale is also 
——— et found, and compari- 
Fe, 378—Jackson's.ere-pivoe micrometer. son mads accord- 
ingly. All that need 
be done is to substitute the terms of the arbitrary scale for screw 
values in the preceding exam; ples, and they will meet the ease. 
The arbitrary scale should he capable of movement by a screw, 











234 ACCESSORY APPARATUS 
‘We shall describe what we consider the most practical forms of 
of antiquity Wollaston's camera lucida claims it 
; but to use it foayn peneseaoquny seen Sy 
Its general form is shown in fig. 179. The rays 


on leaving the eye-piece, above which it 
ao two poets ic 





Fio 1 of the prism bisects the pupil 
inter wutas panil reskin “4 
microscopic image and the other half the images of the paper and 
the hand employed in drawing. If this bisection is not equal, too 
much of one image is seen at the expense of the other. This was in 
some sense sup] to be compensated by the use of lenses, as seen 
in the figure ; but the difficulty of oa PRD eae poem 
ition has caused this instrument to several 
now Rene ae ore ne Sateen At die nevertheless oe 
int in its favour—it not invert the image, causing tl 
at tebe turned to the left, and vice eersa. This is an advantage: 
the value of which we shall subsequently see. 

A simple camera was made by Soemmering by means of a sinall 

mirror or cireular reflector, which is placed in the path of the 
went pencil at an angle of 45° to the optic axis, thus reflectin, 
rays a the image upwards. The instrument is seen in fig. 180 
and slides on to the eyepiece. The reflector must 

j be smaller than the pupil of the eye, because it is. 
through the peripheral portion of the pupil that the 
rays, not stopped out by the mirror, come from the: 

per and pencil. Hence, as in the ease of Wol- 

. ins camera, the pupil of the eye must be kept 

Fro. 150—Simplo perfectly centred to the small reflector, As there 

bi is but one reflexion, the image is inverted but not 

transposed, To see the outline of the image as it is in the micro- 

eae the drawing must be made upon tracing paper, and inverted, 
looking at it as a transparency from the wrong side. 

There is considerable variety in the experience of different 
microscopists as to the facility with which these two instraments 
ean be used. The difference in all probability depends on the 
greater normal diameter of the pupils of the eyes of some observers 
in comparison with that of others. 

Dr. Lionel Beale devised. one of the simplest cameras, which 
has the advantage of being thoroughly efficient. It consists of 

iece of tinted glass placed at an angle of 45° to the optic axis, 
in the path of the emergent pencil. The first surface of the glass 
reflects the magnified image upwands to the eye, the paper and 









CAMERA LUCIDAE 235. 


pencil being seen through the glass. Tn its simplest form it is seen 
in fig. 181. The glass is tinted to render the second reflexion from 
the internal surface of the glass inoperative. The reflexion of the 
i is identical with that of Soemmering's, 
ig. 182shows a fitting adopted by Bausch and Lomb forthe neutral 

tint camera, It is made 
of vuleanite, und the half f, 

ing to which the frame 
holding the neutral tint 
gis is fixed, fits on the 
cap of the eyepiece, and 
with sufficient grip. 

Amo the camera: 
Iwoider achieh project te 
image of the paper and 
pencil into the microscope 
tube in first that devised 
by Atmici, and adapted to 

horizontal microscope 
by Chevalier. The eye 
looks through the miero- 
scope at the object (as in 





Pi, 181 —Beale’s enmern. Fro. 142—Bauseh and Lomb’s fitting for Beale’s 
twntral tint camera lucida. 
the ordinary view of it), instead of looking at its projection upon the 
Juper, the imageof the tracing point being projected upon the fleld—an 
arrangement. at is in eee 
respects moreadvantageous. This 
is effected by combining a per- 
forated silver-on-glass mirror 
with a reflecting prism ; and its 
section will be ner by The 
accompanying diagram (fig. 153). 
‘The ray + proceeding from the 
object, after emerging from the 
sye-piece of the microscope, 
through the central per- 
in the oblique mirror M, 
which is placed in front of it, 
and so directly onwards to the 
eye. On the other hand, the my 
#, proceeding upwards from the 
ing point, enters theprism P, 
is reflectéd from its inclined sur- Wa! 188, 
face to the inclined surface of the "a 
tairror M, and is by it reflected to the eye at 5’, in such parallelism to 
the ray } proceeding from the object that the two blend into one image. 





236. ACCESSORY APPARATUS 


‘The Editor has used with great facility and devised 
by Dr: Hogo Schrdder and Praiecal by Mears Rows Tee figured 
a 


at consists of a combination ‘ 
185) A'B Cand a showboidea prism DET eared ah bee 
very ( @ thin stratum 
a tee oD Bae betes 
ne hick 





to the optic axis of the mi the axial ray H 
passes without refraction to I ‘on the internal fuoo BP; whesco 16 is 
is 





* ” 
Fi0. 165 —Diagrain explaining Schriiler's camera Tneida. 





luminosity of the dma The angle G is arranged so that the 
extreme marginal ray H’ from the field of the B Peifetirs strikes 
upon DG at a point just beyond the angle of total reflexion, the 
diffraction-bands at the limiting angle being faintly discernible at 
this edge of the field. This angle gives the greatest amount of light 
by ordinary reflexion, short of total reflexion. 

Tn use, the microscope should be inclined at an angle of 45°, and 
the image focussed through the eye-piece as usual ; the camera is 
then placed in position on the Be piece, and pushed down until the 
image of the object is fully and well seen. The creving pate must 
‘be fixed upon a table on a level with the stage immediately under 
the camera, The observer will then see the microscopical image 
jected on the paper, and the fingers carrying the pencil point will be 
clearly in view, the whole pupil of the eye being available for both 
images, the diaphragm on the instrument being considerably larger 
than the pupil. ‘The eye may be removed as often as required, and 
if all ix allowed to remain without alteration, the drawing may be 
left and recommenced, without the slightest shifting of the image. 

Téa vertical position of the microscope be needful, this may be 


238 ACCESSORY APPARATUS 


that there is a sort of ‘knack ’in the use of each, which is commonly 
acquired by alone, 80 that a accustomed to the use 
of any one of them does not at first work well with another. 


some persons at once acquire the power of seeing the and: 
tracing point with ini ore equnty 
otherwise ; and hence no one should to be) by 
the failure of his first 


ce 

been obtained, the eye should be held there as steadily as 
sible, until the tracing shall have been ‘Teta essential to 
keep in view that the ‘ion between the size of the tracing and 


courie, it in ‘ 
tracings is teiny mace of any set of objects which it is intended 
delineate on a uniform scale. 

A valuable adjunct to a camera lucida is a small paraffin 
seen to the left jate TIT, which illustrates the correct meth 
using the camera lucida ; this lamp eae and is capable of 
raised or lowered, fitted with a paper shade, for a deal of the 
success at ton the use of the camera depends on the relative 
ilk on of the microseopie image on the one side and of the paper 
and fingers and peel of the exeeutant on the other, It is nota matter 
to be determined by rules ; personal equation, som 
determines how the light shall be regulated. Many 
draughtsmen use a feeble light in the image, and a strong light on 
the hand and paper, and others equally successful manipulate in 
the precisely reverse way. But upon the adjustment of reapec- 
tive sources of light to the personal comfort of the draughtsman 
will depend his success. 

Care must be exercised in this work in the ease of critioal tnuiges. 
‘These must not be sacrificed either by racking the condenser into or 
out of focus, or by reducing its anal by a diaphragm. If the in- 
tensity of the light has to be reduced, it must be done by the inter- 
position of glass screens, and this is beautifully provided in Abbe's 
camera. The illustration of how the various apparatus for the use of 
the camera lucida should be disposed, given in IIT., may be pro- 
fitably studied. Both mirror and bull’s-eye are turned aside, and the 
hand and pencil are illuminated by the led lamp. 

‘The lamp illuminating the image is seen, with such » sereen of 
coloured glass as may be found needful, and the Jamp illuminating 
the paper and pencil, and carefully shaded above, is also seen at the 
eye-piece end of the bory-tube, Often, if the image is too bright, 
we find that bringing the lamp down to illuminate the paper more 
intensely suttices. If not, use screens ; the illuminating cone must 
not be tampered with. 

IMM. The determination of magnifying power ix an important 
and independent branch of this subiect. For this purpose, and for 


ee 








HOW TO DETERMINE MAGNIFYING POWER 239 


the reason given above, Beale’s neutral tint camera! is eminently 
suitable—indeed, is the best. We can easily and accurately measure 
the path of the ray from the paper to the eye. What is necessary is 
to project the image of a stage micrometer on to an accurate scale 
placed ten inches from the eye-lens of theeye-piece. There must be 
complete accuracy in this matter. 

We can best show how absolute magnifying power is thus deter 
mined by an example. 

Suppose that the magnified image of two yzg,ths of an inch 
divisions of the stage micrometer spans ;',ths of an inch on a rule 
placed as required ; then 

(i) 002 inch : +8 inch : 
pe at = 400 diameters ; 
for it is obvious that under these conditions one inch bears the same 
proportion to the magnifying power that y;3;5ths of an inch bears to 
yoths of an inch. 

Suppose, now, as it sometimes happens, that the operator is pro- 
vided with a metrical stage micrometer, but is without a metrical 
seale to compare it with, there being nothing but an ordinary foot- 
rule at hand, 

Let it be assumed that the magnified image of two ;},, mm. when 
Projected covers y'; inch ; then, as there are 25-4 mm. in one inch 





inch : power ; 






1 @ power ; 
= 1016 diameters. 


Ié the reverse.is the case, viz. that you have an English stage 
nicrometer and a metrical scale, then, if the magnified image of 
two ydsu inch spans 18 mm., 


(ii) 2 inch JE e125 
ee 1 _ 354-3 diameters. 





The above results indicate the combined magnifying power of the 
objective and eye-piece taken at a distance of ten inches. The arbi- 
trary distance of ten inches is selected as being the accommodation 
distance for normal vision. 

The magnifying power, however, is very different in the case of a 
myopic observer. Let us investigate the case of one whose accom- 
modation distance is five inches. 

Here he will be obliged, in order to see the object distinctly, to 
form the virtual image from the eye-piece at a distance of five inches. 
To do this he must cause the objective conjugate focus to approach 
the eye-lens ; consequently he must shorten his anterior objective 
focus, In other words, he must focus his objective nearer the 
object. This will have the effect of causing the posterior conjugate 
focus to recede from the objective towards the eye-lens, and the fact 
of bringing the inverted objective image nearer the eye-lens brings 
algo the virtua] image of the eye-lens nearer. 


1 Page 285, 








ma 


240 ACCESSORY APPARATUS: 


Shortening the focus of the objective has the effect of increasing 
ietstes wives Ginuiena i Hoidieweted 


increase in power is small ; but i the eye-piece 
‘virtual fron ten tofive incheslias the effect of nearly ng its power. 
ity the combined result of the i aod jective Sn 


the case of halving the eye-piece virtual is to nearly halve 
of the microscope. The incrense of the objective power is | ly 
so small that it may be neglected.! In practice it is found by us 
that if the image is projected on a ground glass screen ten inches 
from the eye-piece, the image is nearly the same size whether 
focussed by ordi or myopic sight. is in harmony with 
Abbe emontraton (pp 23, 25,2) that ah ign ae en 

on 


under the lent aat ela Rothe ee eee 
‘ght at toa ‘fica ti 
Pe el ry vision. < 


multiplying power of any eye, is not 80 . A laborions 
sian involving the nies of the aieaneen thickness, and 
refractive indices of the lenses, is ired. But « very approximate 
apie ion, esis feniae for all practical may be 

i le, ial one a ni camera at 
Ban ‘The prin "fs as follows, re 

Select a medium power—a 4-inch is very suitable. Now 
with the microscope in a horizontal position, and with a 
illumination, project the image of the stage micrometer on to asereen 
distant five feet, epee from he Mack Jena koe the objective. If no 

oto-micrographic camera is at hand, it wi necessary to perform 
re esperinent ia a darkened room aiading, the Tawiae source. 
Divide the magnifying habia thus obtained by 6 ; the quot will 
give the initial power of the lens at ten inches to « very near approxi- 
mation. 

The reason why the result is not perfectly accurate is that the 
ten inches must be measured from the posterior prinslpel focus of 
the lens, and that is a point which is not given. But in the oase of 
a power such as a 4, it is, in practice, found to be very near the back 
lens of the objective. So by taking a long distance, such as five feet, 
the error introduced by a small displacement of the posterior prin 
cipal focus does not materially amount to much, 

‘There is a further error introduced by the approximation of the 
objective to the stage micrometer in order to focus the conjugate at 
such a distance, but this is small. We can see, therefore, that this: 
error tends to slightly increase the initial magnifying power. 

‘The initial power of the } being found, and its combined magni- 
fying power, with a given eye-piece, being known, the combined 
power divided by the initial power gives the multiplying of 
the eye-piece. Cure must be of course taken to notice the tube- 
length * when the combined power is measured. The initial power 
of any other Jens may be found by dividing the combined power of 


1 English Mechanic, vol. xlvi.No. 1185, Article on measurements of magaifying: 
power of microscope objectives by E. M. Nelsan. 
1 Ibid, vol. xxxviti. No.0, ‘ Optical Tube-length,’ by Frank Crisp. 





242 ACCESSORY APPARATUS 


er objective was being focussed, This objection has been entirely 
removed by the introduction of the bent form by Messrs. Powell and 
Lealand, and others, shown in 189-192. There can be nodoubt 
that for ordinary dry lens work some such device is imperative. 
Some, however, who do a very large amount of mi work 
prefer to use two microseopes ; the one « third or fourth micro- 
scope, with only a course adjustmentand a 1-inch objective and mirror, 
the other having a coarse and fine adjustment and a }-inch objecti 
with a sup form of condenser and plane mirror, all fine and 
power work being left for a special microscope. 

The one drawback to the use of a rotating nose-piece is the extra. 


ive: 





Pre. 191. Fro. 192, 


weight it throws upon the tine adjustment. As this subject is fully 
treated of under the heading of * Microscope’ no more will be said at 
present than that a double nose-piece is to be preferred to a triple, 
and a quadruple need not be entertained for a delicate instrument 
unless itis required to find out in how short a timea fine adjustment 
may be ruined ; for let it be noted that a 2-inch, l-inch, }-inch, and! 
4-inch objective of English make weigh together 8} oz. without any 
nose-piece. 

For the proper use of a rotating nose-piece the length of the- 
objective mounts should be so arranged that when the objective is- 
changed little focal adjustment will be necessary, 

An excellent calotte nose-piece for four objectives is made by 
Zeiss ; this is so arranged that only the optical portion of the objec- 
tive is screwed into the nose-piece. This plan much lightens it, so- 
that the nose-piece and the four lenses weigh 3} oz, or only 1 oz, 
more than an English }-inch with a serew collar, and }.oz. more than 
an English 4-inch of wide angle. 

A centring nose-piece has heen made with the view of placing 





ACCESSORY APPARATUS 


grooved nose-piece, These adapters, which are wedge-shaped 


244 
into the 7 
and ‘face up,’ have two novel features, Arp tein Rvp oe dia 


adapters to 

objectives, psn ® change of objec- 
tives is made little change of focal 
adjustment is required. Figs 193, 
194 show the nature of this arrange- 
ment. In Nelson's changing nose- 
piece a small ring with three studs ix 
screwed on to the objective ; a nose- 
Heat is screwed on the microscope 


nes. ‘Therefore, by placing the 
ern into the slots nage the 
objectiven quarter of a turn, the studs 
run up the inclined planes, thus causing the flanges to face up tightly. 

Mr. Nelson has pointed outa far better and simpler method 
which dispenses with all extra ay tus, 

‘Three portions of the thread in the nose-piece of the mi 
itself are cut away,andalaothree portions on the serew of the objective. 
‘Those portions where the thread is left on the objective pass th 
those spaces in the nose-piece where it has been cut away. 
screw engages just as if the whole screw were there and the objec- 
tive faces up in the usual manner. This plan in no way injures 
either the microscope or the objectives for use in the ordinary way ; 
thus uncut objectives will serew into the nose-piece, and cut objec- 
tives will serew into an uncut nose-piece. This plan is similar to 
that employed in closing the breach of guns, and it was seeing one 
of them in 1882 which suggested to Mr. Nelson to adapt the same 
principle to the microscope. Subsequently it has been found that 
in 1869 Mr, James Vogan had proposed much the same plan, on! 
cutting away two portions instead of three ; it is curious that sm 
an excellent idea was allowed to drop. 

An anilysing nose-piece ia that which carries a Nicol’s analysing 
prism for polariscope purposes. In some the prism is in the 
uose-piece, whereas it ought to be capable of rotation. Lastly we 
have a revolving nose-piece for the purpose of testing objectives, 
‘Mr. Nelson, in a paper read before the Quekett Microscopical Club, 
February 1885, stated that he had observed that certain objectives 

formed better when the object was placed in a definite azimuth. 

With a view to climinate any possible alteration which might ariso 

from the revolution of the object with regard to the light, he had 

designed a revolving nose-piece which enabled the objective itself to 

be revolved true to the optic axis when any imperfection in its 

formance in a particular azimuth could he immediately noted. 

is plan had, however, been previously in use by Professor Abbe 
for a similar purpose, but not, as we believe made public, 


Fra. 104.-—The objective detached 
froin Ue bedly-llde. 











4 





an estimated hall 

this but less than 42, it ix lo red * = 
the lens we recommend is one of i 
‘ing six diameters, icing Qa ea ins 
are furnished with a handle, which may be used ornot at # 
the worker. : 

» The other finder we desire to consider is called after its inventor, 

and is known as * Maltwood’s finder.’ ? ‘ 


Tt consists of a micro- , one square inch in size, divided 
into 2500 little Ker al seo bg is auth inch aquare. Each 
square contains two numbers, one indicating the latitude and one the 
longitude. To log any object the slide containing the object must be 
removed and the slip holding the micro-photograph substituted for it, 
then the figure in the square which most nearly with the 
centre of the field is noted. Of course, both the Guede an the 
Maltwood finder must be carefully made to abut against the stop. 

There are two drawbacks to this finder. 
ri i ‘The divisions are not fine enough, so that it is only suitable 

for low 

2. The removal of the slide, and its substitution by the Maltwood 
finder, renders it extremely unhandy when using an immersion objec- 
tive, all the more so if scence tare to be immersed as well. 

If the Maltwood finders are made alike, they are then, of course, 
interchangeable, ' 

Dr. J. Pantocsek describes a finder,? which appears to have some 
ndvantage not possessed by that of Maltwood, which he considers in 
compari: = a aagiioncy beh *y i 

ines are drawn on the stage at right an: int ing in 

the optic axis ; these are check g Lines a atietra tafe are 
drawn parallel to those on the upper half and the left half of the 
finder, thus giving horizontal lines in the right upper quadrant, 
vertical lines in left lower quadrant, and squares in the left 
‘upper one, Each ten of the lines is marked as shown in fig, 195. 
‘ 9 Soc. new series, vo). vi. : 

1 Zetoehl Wan hte So. 885 pp. AAAs aE MS, 1880, p19 





a 


THE IRIS DIAPHRAGM 247 


When the object is in the field note is taken of the two lines on 
which the left and r sides of the slide rest ; thas, 42/11. 
—There are three kinds of diaphragms in use. 
monest form is that of a rotating disc of several aper~ 


i 


Fig. 195.—Dr, Pantoceek’s finder. 


‘tures graduated as to size. Secondly, a series of separate small disce 
ot metal, with a single central aperture, which fits in a suitable 
arrier, Thirdly, there is what is known as the‘ Iris’ diaphragm, 
whieh, in its new form, made with sixteen shutters, has been brought 
to great jon by Mr. 
Baker, is also beautifully 

dy Zeiss, as shown in 
fig, 196. In whatever form 
the diaphragm may be which 
is for use with the mirror, it 
is important that it should not 
be too near the object, 
us then it does not lie in the 


ena) effects, Therefore itis yo, 
better to use a larger aper- 
ture further away from the stage than a pin-hole near the stage. 


ites Trie dinphragtn. 





When a diaphragm is used in connection with a condenser, it 
should be placed just behind the back lens, and never above the 
front lens. Calotte diaphragms placed close under the stage, and 





' 





which een much in use lately both here and on the Continent, 

are a ’ : 

A very, ay of down a cone from @ mirror is to have 
ponies vie 


aleve i T can be made to advance or recede 
from the ‘The advantage thus gained is that one ; 


s rh 3 
those who suj and affirm that this is all that we need—that the 
objective is the microscope—cannot understand the nature of modern 
critical work. The im of it could not have been realised in 
the sense in which we know it in the earlier dates of the history of 
the instrument ; but at as early a period as 1691 we pointed out 
{p. 135) that a drawing of Bonanni’s horizontal microscope showed 
sracidsent’ lake compound condenser. It is, in fact, of some 

seats to note how oe modern, oalioes Les ny 
he mi at amor older ty appears. 
most efficient ae suited for the examination of objects by trans- 
mitted light was that of Hartsoeker, p. 135, fig. 102. It be re- 
mer that it not only was furnished with a condenser, but with 
a focussing arrangement to be used with it, which was not in any 
way affected by a change of focus in the object. This is a feature 
which, although not then important, is of the utmost importance now. 
In the correction of d in the lenses employed in the 
ie form of microscope so much difficulty was experienced that. 
several efforts were made to luce cat forms of the instru- 
ment ; the most successful of these was that of Dr. Smith, of Cam- 
aide, in 1838 ; but this and all other forms of reflecting microscope 
had but a brief existence and passed forever away. To the improve- 
ment of simple lenses much of the earlier progress of microscopic 
investigation is attributable; and that known as ‘ Wollaston’s 
doublet,’ devised in 1829, was a decided improvement in all respects. 
Tt consisted of two plano-convex lenses ; but this was again improved: 

s We iv. 
7 Quskett, Micro, Zourn, vo. iv, p. 181 ab 


‘condenser’ thi ont this work dl to optical appliances for 
the sub-stage; what in tnewa as the *bull'seye" teat a peor Pe 





and as the lens he employed was a. 
of } of an inch focus, the method of focussing the was as 
any other, because the dit was ata distance 
hetereean lease Sry eens . so that nes 
between foeus, and * whit ud! focus, or the focussing 
of the image of a white cloud upon the object, was nov great. 
But Browster was writing of a candle-flame when he on the 


objects in the‘ Pem 2 ese were — 
1. That the illuminating cone should equal the aperture of the 
objecti ‘more, 


and no 

2. With daylight, a white cloud being in focus, the object was 

to be placed nearly at the apex of the cone. object was seen 

better sometimes above, and sometimes below the apex of the cone, 
4, With lamplight a bull’s-eye is to be used to parallelise the 

rays, so that they may be similar to those coming from a white cloud. 
Of the old of condenser, that devised by Mr, Gillett was, 





bad practical work, as well as from 
Fio, 197;—Gillett's condenser, from ‘Hogg the fact that they are so 
‘on tho Microscope.’ 


rl 


pe as not to a daha 
st mal arrangement 
of din] and stops an excellent aon it is not clear why it 


has fallen into disuse. 

It had been the custom to recommend the use of this instrument 
racked cither within or without its focus. Marpaniee sapere it 
without and Quekett within, and one or other of these me was 
general, But in the use of good achromatic condensers with high- 


252 ACCESSORY APPARATUS 
session of these three essential qualities it has stood unrivalled for 


Cee EL Meer 
The removal of the front lens of this condenser, which may be 
readily unscrewed, reduces it in power and angle, and therefore 


and is much lower in both power and aperture than that of 
makers ; but by sliding off the front cap into which the front lens is 
burnished both and re may be further reduced. It is. 
achromatic, and is a practical and useful instrument capable of adap- 


Sec bie ei ps, con- 
iderable value, special; 
adapted to lenses of low ree 
and up to those of } inch 
focus, has just been constructed 
and placed in our hands 
Messrs, Powell and Lealan 
Tt was made in response to the 


its purpose. It is achromatic, 
Fro, 198,—Swift's condenser. has a numerical a) re of 


=i panel se cei 
of +5, and for dark-ground illumination is of the highest 
qualities. Its power is a 3 inch, and will prove a most useful 
adjunct to the -micrographer, since it will enable him to get a 
large image of the source of light on the object; but its aberrations 
are not so perfectly balanced as we could desire. 
It is possessed of « new feature so far as the condenser of these 
makers is concerned, having permanently placed beneath the 
ical arrangement an irie diaphragm, and in addition the eon- 
lenser mount is supplied with a series of diaphragms and iataps which, 
are placed in a turn-out-arm carrier ; this provides the er with 
facility as well as accuracy of method, since both of these can be: 
used under the same adjustment, The aperture of the cone trans- 
mitted by the condenser with each diaphragm is engraved upon that 
diaphragm, and with the stops fordark ground; the aperture of the ob- 
jective with which the stop will yield a dark ground is also ved. 
on it. This embodies the recommendations we have made below. 
We give an illustration which is self-explanatory of this appa- 
ratus, fig, 200. 
Before the introduction of the Seat system, and the 
production of such great apertures by Powell and Lealand as. 








ACHROMATIC CONDENSER OF LARGE APERTURE = 253 
a ID in a jth, a yyth, and a Q.th of an inch focus, the 
Seep Pea Leora condenser ih 


‘a dry was as 
Laas ane ed gr But 
such as these, and 
the tpockromtia ayeten of 
lenses, much larger cones were 


by an achromatic instrument of Pye, 200—Powell and Lealanil's new low- 
value onthe same system. power condense 

is combination consists of a 

ooh coreaeeny with two doublet backs ; it is nearly of the same power 

as dry achromatic condenser, but is of much ter aperture. 

Tt has heen brought still more recently to a very high state of per- 








Fro. 21. Fro, 202, 


OO® OO®@ 


Powell ani Lealand’s high-power achromatic condenser, 


fection, having an aperture of 1-40. It will work through a mount- 

‘ing slip of Of, aad for aperture and working distance is, like its 

ir, quite unap} 

oti a view of this instrument in figs. 201 and 

202, but it will be found that other stops than those illustrated will 

‘be required, some of these being of little or no value; while the 

stops made with rings may be made much less expensively of the 

same form, but without the outer rings, having merely three points 
or arms to rest: upon the edge of the socket which receives them. 





i 
g 
af 
a5 
z 
F 
4 
5 


i 
: 
i 
i 


ing experts that, as we increase the cone in aperture, we 
increase the perfect rendering of the ii until the point is reached 
where the aay from oo Sas is equal to the Le of the 
objective, and, whatever be the object used, it is advisable not to 
exceed this, "With the most perfect objectives of the present day, 
we find in practice that the best results are obtained when a cone of 
light is used, which, on the removal of the eye-piece, is found to 
occupy three-quarters of the area of the back lens of the objective. 
© condenser is sufficiently free from spherical aberration to 
transmit a cone equal to its own aperture. Condensers are all more 
or less under-corrected, and consequently focus their central rays at 
agreater distance than their marginal rays. If we rack up the con- 
denser so that the marginal rays are focussed on the object, the focus. 
of the rays which pass through the centre will be beyond the object, 
It is well known to those practised in mic y that in the 
case of a narrow cone, from a well-stopped-down that is, 
a condenser used with diaphragms of relatively small diameter—the 
illumination is at its greatest intensity when the object is at the 
apex of the illuminating cone, and if the condenser is racked either 
up or down the intensity of the illumination is rapidly diminished, 
But in the case of a condenser with great aperture, if it be racked 
up the marginal rays will have their full intensity, while those which 
through the central portion of the condenser will have « 
diminished intensity. 
The extent to which this will take place will be wholly dependent 





end is ol sesuteeactcenees Anping 
is t one It. i 
ny Beith! but without the middle, combination, “its 


Tn its present form it reverses its primary construction. It is 
now made with a double front and a single back, instead of a single 
front and a double back, 

An achromatic condenser which has been very Jargely used in 
England and America, and which has secured great deal of com- 
anendation, is that of Professor Abbe. The optical productions of Abbe 


ignorant of the value of any condenser, have at once perceived the 
enhanced value of the results yielded by its means, 

To those who have made the scientitic use of the microseope « 
careful study in England it hus & persistent source of regret 
‘that it has been so long and ertinaciously tangit tind Bae Beene 
histological microscope must be of the Hartnack type, and that it 
should be used with narrow-angled dry lenses, perhaps a }th-inch 
focus, and no illumination but that afforded by a simall concave 
mirror, the focal lere of which is extremely doubtful or unknown, 
and in practice w! cineca No doubt a student instructed 
on these lines would be ustonished indeed when he such 
a practice for the illumination and improved image afforded by an 
Abbe ney oom “ ae 

Usually such exchange of illuminating method presages an ex- 
change of instrument, for the scientifically imperfect and wholly 
unsatisfactory ‘tool’ that is in the majority of cases put into the 
hands of the medical student. will not lend itself even to an Abbe 
condenser, 

‘The fact is that a large part of the ndmiration that has been ex- 
pressed for this condenser has resulted, not from a comparison of its 
results with those of other high-class achromatic condensers, but of 
images obtained without any sub-stage optical arrangements at all, 
placed in contrast with the results obtained by using this condenser 

inst the same objective when used without its aid. But that even 
saan images are entirely inferior to the images obtained by the 
higher order of achromatic condensers we only require the practical 
testimony of Professor Abbe to prove; for Ae has since cod an 
achromatic condenser of much merit, to which we give consideration 
below, 

In its most perfect form this chromatic condenser of Abbe’s con- 
sists of three single lenses, the front being hemispherical, and the 

2 Page 252, fig. 109, 





IMPORTANCE OF AN APLANATIC CONDENSER 257 


two lower lenses form a Herscheleian doublet. This combination iz 
shown in fig. 207, and the form of the instrument as applied 
to Zeiss’s own microscopes is shown in fig. 208, 

Sera cian poe Soren is low, and its aperture is very large 
(136) ; beyond the fact that it is not achromatised it has 
enormous spherical aberration. The 
distance between the foci of the central 
portion and of a narrow annular zone 
whose internal diameter is [th-inch is 
7 Sera Its aplanatic aperture is 

only 5, Now, whilst it is a 

of no inconsiderable character to 

ve an achromatised condenser, and 
eek with ersten ok lng thn. 7 Qn sree 








Fie WH, —Abibe's chromatic condenser us ayplied to the Zeiss microscopes, 


of vital importance is that it should be aplanatic ; the best condenser 

is always that which will transmit the largest aplanatic cone. At 

the close of this section wo furnish a table of the relative qualities 

Gt the condensers of the best construction now accessible to the 

microscopist, and a reference to this will show that Powell and 
8 





258 ACCESSORY APPARATUS 





N.A.; for illumination, in fact, it is, the ul 
minator extant, and shows objects on a dark ind with sparkling: 
brilliancy, and may be used with polarised Tight. . 

A chromatic condenser, somewhat similar in construction t 
and of low price, is made by Messrs, Powell and Tealand, but it 
of inuch ieher power, ES that the distance este ae foci for 
the central i i is not so it, und on this account 

Sepersl ge A Shen asians Se 
aplanatic cone. This in- 
strument with its din- 
rena ragmsis shown in fig. 209, 
reseaa it is more convenient in 

e form, and can be handled 
and adjusted with greater 
facility, than that of Abbe. 
The size of their respective 


Es 
= 
ae 


‘Abbe ing 1y% inch, 
The diaphragms (fig. 
210, A) have a central aper- 
ture, for the purpose of 
centring, and the move- 
ment is made by means of 
anouter ates tube.b, ake 
a slot at the top in which 
Himatieal'eondenoee, "the arm A. fits, and another 
arm, B, is placedat thelower 
ond 80 as to give ready command of the rotation. This plan allows of 
the use of one or two oblique pencils incident 90° apart in azimuth. 
‘The condenser thus mounted isonly intended as an oblique illuminator. 
It forms one of the best of the very cheap condensers when it is 
mounted in a plain tube mount with « ledge to hold the diaphragms. 
D is the optical part of the condenser placed immediately above the 
diaphragms and in oil-immersion contact with the base of’ the slide, 
‘The circular diaphragm is fixed into the inner tube attached to the 
sub-stage tube, O, just below the position of the arm A; the other 
diaphragm is screwed to it by a screw in the eccentric hole, shown 
in each, It will be seen that when the diaphragms are placed 
together in this manner the movement of the arm will produce the 

changes in the light as above mentioned, 











QUALITY OF ABBE'S ACHROMATIC CONDENSER 259 


As we intimated above, Professor Abbe lias now produced an 
achromatic condenser, steno in high pow 
work, but in fact of much more general utility. 

Fe alli two double backs, and it a 


of the source of redrrlatwd 
ima eg inh fsa has tal apertre 10 
Its, 0 ac aecceptmedrnter it transmits « 
Trt aplatisoe tanta for whereas the former gavo 


anor 


Fim, 211.—Abbe's achromatic condense, 


cone of “5, this instrument yields a similar cone of 
it is large and heavy; and, with great defer- 
to our Continental neighbours, we would suggest that 
eral characteristic; the back lens in this case is 
in ries while barely } of an inch i is utilised 
itting its largest cone. The instrument is repre- 
but om excellent modification in fitting it to 
has been made by Mr. Charles Baker, tho 
si is shown in fig. 212, where it will be seen. that 


ie 
‘il 


fe 
ua 


tara s is 
and an 

idophres ‘can be used with 
case this. This 
“turn-out” arm carries a disc 


sf metal to receive the din- 
teresa ko, Over this 
fitted a ring into which screw 





aeviet willallow other 

to be used on the 

one mechanism. 
‘The metal dise should pare ‘ 

central aperture as ; ‘. for Abbo's 

the ‘back lens of any MA tien pogo ieered 
° tobeused with scopes. 

the me It should be thick enough to receive two stops or dia- 


¢ mount. 
Phmgms ata time. This power to alter a diaphragm or stop so as 
7 a2 





we 
for the lowe ae ser, and wice rere. 
We may note that for dark-ground work stops should be placed 
close to the back lens of the condenser, and in the case of a dia- 
pepe ie inch of distance should not 
‘The iris di is for general purposes more conyenient than 
inns eee eter it has the drawback of being incapable 
of setting to any exact size, A delicate point in an image, caught 
with a certain-sized diaphragm, is not regained with ease and cer- 
tainty with the iris! and may involve much putience and labour ; 
but a well-made /arye plate of graduated diaphragms will wholly 
remove this difficulty. Moreover, for testing object-glasses it is 
supremely important that a metal diaphragm be used, so that the 
conditions of illumination may be readily and tely reproduced. 
Messrs, Beck provide a condenser with a ea top, carrying 
front lenses of different power central with the backs. Tts charncter 
will be readily seen in the illustration given in fig. 213. This com- 
bines a high-, low-, or medium-immersion 
or dry condenser in one piece of appa- 
ratus, The first lens when brought over 
the back combination has a low angle, 
and is intended for use without fluid for 
histological subjects. The next is a full- 
Pease lens, with which, by revolvin, 
the diaphragm, the angle can be vari 
ae ee downwards. The third lens, 
with full aperture of diay hea has an 
angle of 110° in glass = 12 N.A., and 
is truncated, cutting out the central rays. 
Pio. 219-—Beck’s variable con- “Phe fourth Jens has also an aperture of 
oO. 1-25, and is similar to No. 3, but the 
periphery is painted over so as to allow pencils only at right angles 
to . Ingenious us this arrangement is, it is likely to interfere 
with the corrections; and as the aperture is not exceptionally great, 
it calls here for no special notice. 
Tt may be of service to those who are unable or indi to 
Spend considerable sums upon condensers to state that an excellent 
1 It will be that apertures can be exactly reproduced with the iris fn 
photographic Je why cannot they, therefore, in the ease of the microscope? 


The answer is (1) that with wideangled condansirs « very alight difference in the 
aperture makes a very grost difierence in the angle; a similar difference would be 























262 ACCESSORY APPARATUS: 
An of its points may be of service. 
S r tie thea of the mrocope 
spiral to push into 1. 
3. A tube carrying the o combination of the condenser 
sliding into 2, with a pin in the spiral slot. 


ives the usual sul paratus. The outer one receives # 

pas: els and are placed on ‘turn-out’ 
On the w part of this mount of selenites is ascrew, which 
receives the optinal combination of their dry achromatic condenser. 
‘When this is screwed in its place we have a condenser of the first 
order, with a mount of three folycart mete hele 
mount of diaphragms &e. Now from the under part of the sub- 
stage into the inner and revolving ring is fitted the polariser, and 
this leaves little to be desired in practice. 

We would advise the microscopist to avoid condenser mounts 
which carry their own centring movements a) from the sub- 
pay tt It is with regret that we find that this has been adopted 
in Abbe's new achromatic condenser. It is manifestly better to fit 
Ris teeeap aes movenneris to the sub-stage, and then they become 
available for all the apparatus employed with the sub-; » Aplan 
which requires that each piece of sub-stage apparatus which needs 
centring should be provided with separate fittings for this purpase 
aoe nothing to it it. : ye 

¢ give on the adjoining page a list presenting the most iny 
ant Seabaren of the most important condensers, which we teliove 
will be of service to the student and worker. 

The aplanatic aperture given in the table means the N.A. of the 
greatest solid cone a condenser is capable of transmitting, the 
source of light being the edge of the flame placed in the axis. 

The cone transmitted by any condenser is assumed, for practical 
purposes, to be a solid one, so long as the image seen at the back of 
the object-glass when the eye-piece is removed (the condenser and 
flame being centred to the optic axis of the objective, and the source 
of light focussed by the condenser on the object) presents an un- 
broken dise of light, 

The moment, however, the dise breaks, that is, black spots appear 
in it, or its periphery breaks away from its centre, then, as we have 
shown above, spherical aberration comes into play, and the limit of 
aperture for which that condenser is aplanatic has been exceeded. 

The limit given in the table is for the edge of the flame as a 
source of light. When, however, a single point of light in the axis 
is the source, the condenser will be much more sensitive, and a lower 


264 ACCESSORY APPARATUS 


Kensie ofiay seman Ch a Cette inwards), of a 


o-convex lens of crown 1-inch radius of curvature, the 

having a diameter of 1:2 inch, and therefore a thickness of 

Gra oad, ie Srnee wadtece Deny bia safle wan ea 

of 0-56 inch and a depth of 0°5 inch, and is therefore almost a 

sete 2 ioe ects aoe 
in |. Tt is coment a 


The object of the tinh ghee twofold. In the first i 
disposes of three-fourths of the spherical aberration of a concave 
mirror of these dimensions, and enables one to use light which is 
“practically parallel ; and, in the second place, it has the very obvious 
one of securing greater aperture, which is the primary consideration, 





Fro. 215. 





Fio, 214.—Stephenson’s catadioptric 
‘iluminator, 


As fig. 215 shows, rays which enter the flint glass horizontally are 
reflected at the silvered surface of the crown-glass segment, and 
apertures are thus obtained ranging from 0°77 to 1-644, N.A. in 
flint and 1-512 N.A. in crown. 

‘To obtain the smaller apertures, the plane surface of the under 
part of the flint is utilised by cementing to it a segment, F (rather 
more than half), of a plano-convex lens of radius 025 inch, with 
4 focus in crown 0:04 inch above the upper surface of the flint, 
and, therefore, at the upper surface of a slide having a thickness of 
0-04 inch. In order that the rays may be received from the 
mirror beneath (and not horizontally). small right-angle reflecting 
prism, G, is placed with one of its sides opposite toand parallel with 
the receiving side of the flint-glass, 

The aperture of the illuminator is only limited by the refractive 








266 ACCESSORY APPARATUS 


Diack half-cylinder, +, is so fixed by the side of the cylinder 
that if a dot upon its upper surface be brought into the centre of the 
field of view of a low-power objective, its focus, y, will lie in the 
opticaxis. Some skill and sce are required to use this apparatus 
to advantage, but it will amply repay the trouble of master- 
ing its difficulties, Tt is best suited to thin, flat objects ; with those 
that are thick and it lar 
distortion is eases es 
Althoughspecially lesign 
aS a ry caReMe i illu- 
minator, it may also be 
made useful in the resolu- 
tion of difficult test-objects 
hy tranemitted light, the 
illuminator being lowered 
until a coloured spectrum 
appears in the field, the 
rays of which bring out 
their markings with ro- 
umrkable distinctness, For 
use with either of these 
arrangements for * black- 
ground’ illumination, it is 
better that the objects 
should be mounted ‘dry,’ 
especially when they are 
to be viewed under ‘im- 
mersion’ objectives, bal- 
sam-mounted objects being 
thus seen better with dry- 
front objectives. 
This was followed by 
‘dise’ and * button’ illu- 
6.—Wenhum’s reflex illaminator. minators. Mr. Ww enham 
devised the simple illumi- 
nator shown in fig, 217. This consists of « semicircular cise of 
glass (somewhat resembling the half of a button), of half an inch 
in diameter, the sides of which are flattened, while the circular ed 
ig rounded and well polished to a transverse radius of pyth of an inch. 
‘This concentrates the light thrown upon any part of its circumference 
A p onto an et mounted on a slide of the usual 
thickness with whose under side it is brought 
A J 9 into immersion-contact. by the interyention. of 
either water, glycerine, or a more refractive oil. 
As it should be so fitted to the microscope as to 
illuminate the object from any azimuth, it should 
have its flat sides grasped in a clip, which may either be mounted 
on the sub-stage or attached to the under side of the stage, in either 
case haying its diametric section brought up to the under surface of 
the object-slide. By giving rotation to the object, the illuminator 
remaining fixed, the illuminating beam may be made to cross the 














|. — Wenham’ 
jnminator 




















268 ACCESSORY APPARATUS 


tbe instrument, showing the course of the rays tl it, ss Lie 
218, the shaded portion representing the id. 

pen lel rays rr’ r'' (fig. 219), entering its lower surface 

‘on until they meet its parabolic surface, on which ier 
age Stee atlas tered tin arbre and are all directed 
towardsits focus, F, The the paraboloid being ground out into 
peace acre plighlas 8 a sbagenice eireg in from 
it undergo no refraction, since each falls perpendicularly upon the 
part of the surface through which it passes. A stop placed at S 
prevents any of the rays reflected upwards the mirror from 
passing to the object, which, boing laced at ¥, is illuminated by 
the mays reflected into it from all sides of the paraboloid. Those 
miys which pass through it diverge again at various angles ; and if 








Fro, 218—Parabolio 
illaminator. 





Fro. 210, 


the lenst of these, G FH, be greater than the angle of aperture of 
the object-glass, none of them can enter it. The stop S is attached 
to a stem of wire, which passes vertically through the paraboloid 
and terminates in a knob beneath, as shown in fig. 218; and by 
means of this it may be pushed upwards so as to cut off the less 

divergent rays in their passage towards the object. It is claimed 
that this instrament has great capabilities of giving dark-ground 
illumination with lenses of ‘wide apertures’; but that has application 
to the lenses contemporary with its introduction, and nob to wide 
apertures as C1 ag to the lenses of to-day. In comparison with 
what can be done with condensers it suffers greatly after we pass 
the }-inch objective, although it does give excellent results with 


1A parabolic illuminator was first devised by Mr, Wenham, who, however, 

m jpecalam for the purpose, About Aho same time Mr. Shadbolt 
I for the same purpose (nee Tras, Microsc. 
‘The two principles are combined in the glass 














= = 





59 ACCESSORY APPARATUS: 
(fig. spender pe! the 
enn Toe eegeansy wih ec nage 
microscope, hit 
Ese not limiting the 
aaliors Saute hile in 
; le 

the Intter the i is 
ay liter, but a ilar 

pear 
sinssinportan sav that the 
a © 
Se tasre noca moh pat 
, Sons to net 
Mp Fine analysing ag adiaphragin to the con- 
ads ae * pnmies Ee 

when it is used e a 

in combination either with the skeen meth ceadennes, by hich oes 


it may be emp! with high. pa objectives; or as a ‘dark: 
illuminator, which shows many objects—such as the horny pol 
of zoophytes—gorgeously projected in colours upon a 
For ing out certain effects of colour by the use of polarised 
light it is, as already stated, desirable to interpose a plate of selenite 
‘between the polariser and the eds 
and it is advantageous that this should 
be made to revolve. A very convenient 
mode of effecting this is to mount the 
selenite plate ina parevaly ‘ing collar, which 
fits into the upper end of the tube that 
receives the polarising prism. In order 
to obtain the greatest variety of colora- 
tion with different objects, films of 
aoe of different thicknesses should 
Saat and this may be accom- 
pis by substituting one for another 
Fro, 21, in the revolving collar. A still greater 
variety may be obtained by mounting 
three films, which retiree BB three different colours, in 
revolving in a frame resembling that in which hand-magnifiers are 
usually mounted, this frame being fitted into the sub-stage in such 
4 manner that either a single selenite, or any combination of two 
selenites, or all three together, may be brought into the optic axis 
above the polarising prism (fig. 221). As many as thirteen different 
tints may thus be obtained. When the construction of the micro- 
scope does not readily admit of the connection of the selenite plate 
with the polarising prism, it is convenient to make use of a plate of 
brass (fig. 222) somewhat larger than the glass slides in which 
objects are ordinarily mounted, with a ledge near one edge for 
the slide to rest against and a large circular aperture into which 
a glass is fitted, having a film of selenite cemented to it; this 
‘selenite stage’ or object-carrier being laid upon the stage of the 








272 ACCESSORY APPARATUS 


monochromatic light. The Messrs, Zeiss have co 
apparatus (after Hartack) for obtaining monochromatic 
a true form, which is illustrated in fig. 

By means of two prisms, P!, P%, of strong dispersive 
spectrum of considerable length is projected upon the al 
beneath, so that with high powers the entire field is illum 
near approach to monochromatic light, The light enters # 
went through the slit Sp, which is adjustable in width by 
3%, and passes through the prisms and the lens at O, formin 

Sph, where the object. on the stage is supposed to be 
moving the slit by the screw S' the spectrum is a 
ifferent colours following in sua 











274 ACCESSORY APPARATUS: 

Shieh reel Se rs 
adjusted in 

arta sheet the si 


mee 

= bestia oh ihren i 
ae of = og! crater ta tion nt 
compart wach aril opr, alike with he erator 


comparisons of such artificial ordinary or 
natural spectrum, and with is mado for the 
formation of a second im, pet of a 


prism that covers one-hal of this it, and reflects upw: the 
famed through an pertre seen he ign, fede 
Piece. pad ats roduction ar 


i through the body of the 
mi so that the two em 
Th nct position of the’ ab 

ie exact al 
sorption bands is as im} it ms 
that of the Fra lines ; 
and some of the most ieuous 


of the latter afford fi 
Fro. 297-—Bright-line spectromicrometer. Of reference, Bada the same 


spectroscope employed. 

amount of dispersion determines whether the Brambles toe ales 
absorption bands are seen nearer or farther 

Positions in the field of view varying according to ‘he dig 

while their relative positions are in constant ples 
gontaivance. foe moeumring, the spectra of 'avorpion banda ft 
Browning's bright-line micrometer, shown in fig. 227. At Risa 
small mirror by which light from the lamp employed can be re- 
flected through E D to the lens C, which, be means of a perforated 
stop, forms a bright pointed image on the surface of the appr 
prism, whence it is reflected to the eye of the observer, ‘The rotation 
ts) a wheel worked by the milled head, M, carries this bright point 





ie 











276 1 ACCESSORY APPARATUS: 


naflected by adjacent objects. For ordi 
Se ete giou crentotlibe Aare nis 
ie Het Ppa ee neat antec aibignen/ power ae 0e 





Society,’ we 92, 
1867, p. 33, is extremely con- 
vole 1 ocular by 
Ti etral ocular 
Zeiea is another and a wory 
ett form of the wvicro- 
SD saa, 
ther ex} el and it i oY mani- 
fest in the charncter of the 
instrument. Fi, ay represents a sectional view of the instrament, 
It will be seen that the lower part is an ordinary eye-piece with its. 








Fro, 281. 


two Jenses, but in place of the ordinary diaphragm there is a slit, 
adjustable in length and breadth, shown in fig. 231, By studying 


| For further information on ‘The Spectrum Method of Detecting Blood,’ see am 
important paper by De. Sorby in Monthly Microre, Journ, vol. vie 1871, P. 9 








278 ACCESSORY APPARATUS 

thicknesses of the contained fluid, the broad tube higher on. 

one side than the other, and thus Rpctioes Sey 

which, when filled and closed -cover-glass, will a 
thickness of fluid for and comparison. If 

to es eee a preparation of the 

which we commonly we 

of all bring it into the of the objective system. Todo this we 

‘must first remove the tube’ the) open the: hat, 

and use the Us AS A . Tf one has to deal with a. 


the microscope so that the object will be a little out of some- 
what above or psores true semana peal we ge 
uniform spectrum. The spectrum can ii in some: 

cases by likewise throwing the object somewhat out of focus. 





Fro, 282, 


Illumination by Reflexion —Objects of almost every descriptiow 
will require at times to be examined and studied by what is called 
reflected light ; the light in this case is thrown down upon the 
object by various devices, and is reflected upwards through the 
objective. This has been called ‘opaque illumination,’ which, how- 
‘ever, is not a comprehensive, nor even an accurate designation. 
Only « small proportion of the objects examined in this way are 
opaque ; the same diatom, for example, may often with advantage 
be examined with transmitted light, being transparent, and again 
by means of an illumination thrown upon, and reflected up from, its 
surface ; also a condenser with a central stop when used for a dark 
ground shows objects reflected light, but it is manifestly not 
‘opaque illumination,’ designation of this method of illumina- 
tion is consequently more accommodating than accurate. 

There are two very simple means of obtaining this superficial 
illumination when low powers areemployed. The first is the *bull’s- 
eye ’ (which is nowhere in this work called a ‘condenser’; this would, 
as it often has done, lead to confusion) ; it is enough to designate it as 
wehavedone. It is a plano-convex lens of short focus, two or 
inches in diameter, mounted upon a separate stand, in such a manner 
as to permit of its being placed a great variety of positions, The 
mounting shown in fig. 233 is one of the best that can be adopted : 


good results with powers of from 200 to 300 diameters, but 
powers require careful manipulation and yield but doubtful resul 

The second simple method of securing this illumination is to have 
the concave mirror of the microscope capable of being used above 
the stage ' so that the source of light may by its means be focussed 
on the object. Neither of these plans will answer for other than low 
powers, where there is plenty of room for the light to pass 
the objective and the object. The ingenious use of the bull’s-eye 
employed by Mr. James Smith, as detailed above, increases the pas- 
sibility of magnification, but it needs practice and care, 

An illuminator not so well known, or at least so much used as 
its merits justified, is Powell and Lealand’s small bull’s-eye of f-inch 
focus, which slides into an adapter fixed into the su and 
susceptible of its rack-motion up and down, The object is placed 
on a super-stage and lies considerably above, but parallel with the 
pod stage. The bull's-eye, capable thus of being raised or 

|, and of being moved by sliding away from or close to the 
mounted object, has its plane side ae against the edge, and at right 
ii to the plane of the slip, By this means illumination of great 
obliquity can be obtained, att very surprising effects secured even with 
high powers, It was much used by the Editor and Dr. Drysdale in 
their earlier work on the saprophytic organisms, and in the days be- 
fore homogencous lenses, helped us over many difficulties of detail. Tt 
‘was the first illumination toactually resolve the Amphipleura pellucida. 
It could be very easily obtained with a student's microscope provided 

! Soe Journ. Hoy. Mierose. Soe. vol. ill. 1880, p. 398 


i 


282 ACCESSORY APPARATUS 


front, is placed a small plane reflector which covers half of the 
objective, and throws the light directly down upon the object and. 
Ick through the other half. It is shown in fig. 236 with the 
cylinder in place, and in the dotted lines with the same turned out. 
This ent allows of two kinds of illumination, oblique and 
direct, being readily used, as the plane reflector is at to an 
arm so that it can be swung out of the 
way when not required, as shown in 
the figure. 
iz Dr. Sorby was able to get results in 
the examination of polished sections of 
steel not otherwise attainable. 

No opaque illumination, however, 
has yet surpassed the venerable 
Lieberktihn ; the best experts freely admit. that the finest critical 
images to be obtained by this method of illumination are secured 
by the Lieberkiihn, This mode of illuminating opaque objects is 
hy means of a small concave speculum reflecting directly down upon 
them to a focus the light reflected up to it from the mirror ; it was. 
formerly much in use, but is now comparatively seldom employed. 
‘This concave speculum, termed a ‘Lieberkiihn’ from the celebrated 
microscopist who invented it, is made to fit upon the end of the 
objective, haying a perforation in its centre for the passage of the 
rays from the object to the lens ; and in order that it may receive 








Fig. 236.—Sorby's modification of 


the parabolic reflector, 


A B 





Fu. 


its light from a mirror beneath (fig. 237, A), the object must be so 
mounted as only to stop out the central portion of the rays that are 
reflected upwards. The curvature of the speculum is so adapted to 
the focus of the objective that, when the latter is duly adjusted, the 
rays retlected up to it from the mirror shall be made to converge 
strongly upon the part of the object that is in focus ; a separate 
speculum is consequently required for every objective. 











284 ACCESSORY APPARATUS: 







glass may be inserted vee 
the light and the mirror, inches 


four inches is a very useful size for 
a screen, and two or three 


rut what is required aires 
aitinted glass, but a combination of dit 
ferent tints resulting in a correct blue not 
otherwise attainable. 

There is one other kind of reflected 
illumination employed, Boyes prance by the 
vertical illuminator, which, mihousily it 
has been in use for some 
ceived an accession of value from ee ae 
ployment of immersion lenses. It ix pro- 
duced by « device which secures vertical 

‘Fio. 288,—Beok’s light-modifier, Ulumination invented by Professor H. L. 
Smith, of Geneva, US. 

The principle of this illuminator is: to employ the objective as 

its own illuminator, This may be done in several ways. 

1, That of Professor Smith is to place a speculum with an aper- 
ture in it in the body of the microscope at an angle of 45° to the 
optic axis ; opposite this speculum is an aperture in the tube for 
light to enter, It will bo understood by figs. 239 and 240, which re- 

it a longitudinal section of the nose-piece at C of the vertical 
illuminator at ¢, and of part of the objective at d. a isthe aperture 


for ndmitting the mia to the speculum 4, The path of the beam is 


depicted, and it will be seen that on being reflected from the speeu- 
lum it passes through the combination of lenses, making the objective 


VERTICAL ILLUMINATOR—HOW TO USE IT 285, 


denser,’ and is brought to a focus on the object, which is the 
the objective. The rays now proceed from the illuminated 
‘mee more, through the objective upwards, and pass through 
tral aperture in the speculum to the eye-piece and the eye. 
Tolles, instead of this, places small right-angled prism just 
Yack of the front lens of the objective. But this only gives 
2 illumination in one azimuth, and from experience we are 
Ito express dissatisfaction with its performance. 

Mears. R. and J. Beck, in place of a speculum pierced, 
fa disc of cover-glass. The cover-glass is mounted on a 
; fetes. in order that it may be rotated and oblique light 
ad by the milled head, /, A, fig. 240. We believe that it would 
better in practice to fix the cover-glass at the angle of 45°. 
will be seen that by this plan total reflexion may be obtained 
direction and transmission to the eye in another. 








Fro. 239. Fra. 240, 


. Powell and Lealand’s method is to fix a piece of glass, worked 
at an angle of 45° to the optic axis, with a rotating diaphragm 
ont of the aperture admitting the light. 
fo use these instruments the edge of the lamp flame should be 
ed in front of the reflector, so that the rays may be reflected on 
hee back lens of the objective in a line parallel to the optic axis. 
distance from the lamp to the reflector must exactly equal the 
tance from the reflector to the diaphragm of the eye-pieco in a 
ve eye-piece, or the eye-lens of a negative eye-piece, otherwise 
Nays will not be focussed on the object. 
This illumination is only suitable for objects mounted dry on the 
and with immersion lenses. No good result was ever obtained 
tbe immersion lenses were brought into use. 
Ofall the light which is caused to pass out of the front lens of 
sbjective, through the oil and into the cover-glass, that which 
les an obliquity less than the critical angle of glass (41°) passes 








286 ACCESSORY APPARATUS 


H 
l 
i 
iu 


F 
i 
f 


z£ 
e 
3 


is i eye-piece be removed 
oe ae Dents be examined, it will be seen that all 
that of the of the objective whose aperture exceeds 1:0 
is eae Sats seca le repreens Bie eee 
the excess beyond equivalent angle , of which 
itia Ape anes internal dark space is of the exact diameter 
of that of a dry objective of the same focus, and is the maximum 
space which it can itself utilise on a dry object by transmitted light, 


been resolved ; while it is eminently serviceable in determining 
whether any dry- mounted object is in optical contact with the cover- 
it be not so it is invisible with the vertical illumi- 
nator, So also it is instructive to examine the backs of objectives 
of variogs a) with this mode of illumination. A dry obj 
will be wl without the bright annulus, while an immersion of 
1-1N.A, will have « narrow annulus, and that of 1-4 or 15 » broad 
and still broader one. Tn this way, by practice, a fair approximation 
of the aperture of an objective may be obtained. 

It is not the absolute size of the annulus, but the relation of the 
size of the annulus to that of the whole back, that must be estimated. 
‘Thus a jth of N.A. 1-2 will have as broad an annulus as a yyth of 
1-4 N.A,, but the diameter of the back of the 1th is, of course, much 

larger than that of the jth, and this involves the 


necessity of a relative comparison. 

Tn examining objects with those higher powers 
which focus extremely close to the ing glass 
the slightest inadvertence is iikely 0. lead tow 
fracture of the glass, and perhaps to the destruction 
of a valuable slide. This is a serious matter with 
Miller's diatom type slide, or Nobert's test lines, 
or with many others that are expensive or perhaps 
impossible to replace. To remove this source of 
danger, Mr. Stephenson contrived the safety stage, 
shown in fig. 241. The frame on which the slide 

Fro. 241. carrying the object rests is hinged at its upper 
and kept in its true position by slight gS, 
which give way directly the slide is pressed by the objective. It is 
found that springs firm enough to ensure the steadiness Hired 
for high powers may yet be sufficiently flexible to give wasitatcs 
very thin glass is endan, and a glance at the stage shows if it ix 
made to deviate from the normal position in which its upper and 


lower edges are parallel. 





288 ACCESSORY APPARATUS 
disc holder, fig. 246, or it may simply drop into a stage fitting, as in 


a ee (ben in regard to the facility it affords for 

5 in 7 

Bek than ereey ori oe een i being attached 

eee ping i a mae 
the disc 


vat which acts on it by Sry seria works through 
the horizontal tubular stem ; sebilss {.cec bean to kealinn Sp ono 
anor to the other, until its plane becomes vertical, by tu 


whole movement on abe ho ontal axis of peer 
The support! eyes Weed ‘pertorniee a lange 
object may be inate Wy the Lobatkihe if desi The ine 


are inserted into the holder, or are removed from it, by a pair of 
forceps constructed for the purpose ; and they Psat tang 
away, by 
stems: aie a 
forated with Boveral 


Fro, 246, —Bock’s dise-holder. ‘othe value of this little 
iece of apparatus the Author can bear the strongest testimony from 
his own pasetions having found his study of the Foramenifera 
greatly facilitated by it, 

Glass te.—Every microscope should be asaiahes witha 
piece of plate glass, about 3} in. by 2 in., to one panes of which a 
narrow strip ch gla lass is cemented, so as to form a ledge. This is 
extremely aad both for laying objects, nee bet ae a peek 
them—together with their covers, if used when 
the microscope is inclined), and for possarate at sed from injury 
by the spilling of sea-water or other saline or corrosive liquids, when 
such are in use, Such a plate not only serves for the examination 
of transparent, but also of opaque objects ; for if the condensing 
Jens be so adjusted as to throw a side light upon an object laid sd ape 
sole ates the ecient gait A plate or a slip of black paper will 

whilst objects mounted on the small black discs 
hrnget to the Lieberkiihn may conveniently rest on it, instead of 
being held in the ange: pees 

‘Growing Blides Slides and Stages.—A_ numberof contrivances have been 
devised of ibe years for the purpose of watching the life histories of 
minute font organisins, and of ‘cultivating’ such as develop and 

Asmall adapted to take up minute objects may be fitted into 
the soglind ‘hodee in of a dso. 





290 ACCESSORY APPARATUS 
shellac to slide, The minute ‘or spores to be 
oping her ghey ye 

tO ste 
that no extraneous matter is introduced, is over the tinfoil, 
and the he fastened with wax softened with oil, leaving free the 

ea cian i enon cea 

Peed ‘and Drysdale’s Mois 
of 


nl 


‘omti nous ie 
t is needful in working out the 
eee: 
be able to keep the isms in w 
normal and undisturbed condition 
for sometimes weeks at a time ; 
pelea TAS containing 


x x ek en in be under observa- 
Fo, Pa ey be! 2 te 


Piet eae dit this, and still to aed ie vey igh i “4 


a sind Gia st Betis muon iced tate diaa ovie eaere 
tite ordinary sli ing stage of a Powell and Lealand or Ross stand, It 
is thus susceptible of the mechanical motions common to those stages. 
Tts foundation, fig.250, a, a, is plate about the tenth of an inch 
thick, in order to give it firmness, But this ix too thick to work 
th with a condenser and high powers, and therefore s circular 


ee 


5 





i 





Fio. 250.—Dallinger and Drysdale’s moist continuous growing stage. 
aperture, 6, is cut through it, and a thin Nees of good glass, c, de, f, 


is fixed over the under surface of it with Canada balsam ; this may 
‘be as thin as the condenser may require. At the end of the arm 
@, which extends some distance beyond the stage to the right of the 
reader, but when the arrangement is set up on the microscope to the 
left of the operator, a brass socket with a ring attached is fixed with 
marine glue. It is marked in the drawing g, 9, g. The object of 
this ring is to hold a glass vessel, fig. 251, about 1} or 2 inches 








! 
; 


i 
i 
il 





tu 

fig. 253, is the stretched caou- 
tchoue seen at @ in fig. 252, with the object-glass y, 

aud tightly filli up e aperture ¢ in the figure, thus the 
moist charober, ¢/, ch, by enclosing parts /, h, fig. 253, of the A 
which from the glass vessel to the left of the s 

always renewing its moisture ; and with 4, fig. sunk as a 
hy the attachment of the thin glass floor to the under side of the 
stage, as described above, this annular flap of linen overhangs, but 
does not lie upon, the floor on which the of Se ee 
inhabitants is placed. This is a great security against accidental 


flooding. 

Tt will be seen that the instrument must be horizontal ; but there 
is no inconvenience arising from this if it be placed on a sufficiently 
low support, and it will be found in practice that it may be worked 


Fra, 254. 


for a long time without any other change in the arrangement than 
the screwing up or down of the fine adjustment. The difficulties in 
working are few, and ean be best discovered and overcome in 
practice, 

Dr, Dallinger’s Thermw-statie Stage for Continuous Observations 
at High Temperatures.—Tt oelrepe happens that either for the pur- 
pose of experiment, or the study of special organisms, the pet) 








i 


ied 
glass plate and covered with the foe Inss, the 
a cylinder is placed in position, the of a high-power 
is gently forced upon the top of the in HEA ibber through « 
ture, thus forcing iat lower ground surface of the cylinder 
shatinaes and making the space within the closed Manes 
enlly air-tight, but still admitting of capillary 
‘Thus the enclosed air becom 
complete circulation the water in the vessel ¢ (A) is 
slighty below that within the jacket of the stage, and thus 
vapour as well as the mae are near the same thermal point. 
For the admission of illumination and for allowing the use 
various illuminating apparatus, a large bevelled aperture « ©) is 
made between the lower and upper plates of the ean jacket, which 
is found to supply all the accommodation needed. 
There are many other forms of hot stage “a various special 


ead some of eer 
iy lication temas 


these will Be nd in the 
‘Journal Roy. Micro. Soc.” 
vol. vii. ser. ii. pp. 299-316. 
The Live-box and Com- 
pressors.—-What is now so 
well known even to the tire 


zB as the ‘ live-box ’ was origin- 
ally devised by Tay 
was afterwards improved by 
Varley, who in the place of 
a level disc of glass for the 


floor, as well as the top of 

e the ‘box,’ bevelled a piece 
sis hc glass and burn! “= 

it into the top of the tube;. 

Ta ee where it formed the floor of 

this ‘animaleule this prevented the draining off of the 


water at the edge “ api attraction. But in that form = 


ie 
Ae 


ae 





296 ACCESSORY APPARATUS | 


the rings have two zluxs covers cemented to them ; the lower 

is: ne teagan albany mei sy one 
‘on ee which clamps et moe when 
vequired more - cleaning. “pressures of cover. 
laseos aro Obtained bye the in the centre of the 
Ursa pedro halo stage in the same position as the 


it is sometimes required, in very delicate work on very minute 


Fio, 258M. Rewlund’a reversible compressor. 


organisms, to compress them very slowly and with great care while 
we are examining them with ingh powers, The cover-glass is of 
necessity thin, and the pressure the minute dimensions of the 
object must be very considerable in orler to net upon the organism at 
all, FS ee ey heavy compressor 
made by and Lealand of great value. A strong tras plate 
forms its base, and a lever arm carrying the cover-glass of the 
compressor is raised and lowered witha fine screw. The cover-glass 
thay be cemented on to two or three separate fronts which screw 
‘on, and may carry cover-glass of different thicknesses, The cover, 
to prevent flexure, is small, but will work easily with any of the 
modern high-power lenses, ‘The whole body of the ring to which 
the cover-glass is attached is very solid and strong. A glass slip of 























Professor Delage’s parallel compressor. 


the ordinary size slips in, and is clamped by a spring on the base, 
and upon this the cover-glass is brought down in compression. 
An object the 5000th of an inch in thickness can be readily 
held and compressed by its means, but the fronts must be 
turned with great care, and the cover-glasses used for cementing on 
must be much larger than the aperture in the ring, so that a large 
surface may be cemented. 





HOW 70 EMPLOY THE ZOOPHYTE TROUGH 207 


Recently Professor Y. Delage has devised a very admirable form of 
compressor for the most delicate observations (figs. 259, 260) in which 
the is effected by the action of a screw on an inclined plane 
A, and working against the spring R. When the screw is turned 
on one side, the upper part of the compressor con be raised on the 





Pio, 460. —Professor Delage’s parallel compressor, 


pivots B B',as shown in fig. 260, The frame holding the upper 
plate has a gimbal motion on the pivot D (and the corresponding 
neon the opposite side), and the frame can be detached by press- 
ing the a C and the corresponding one on the opposite side, 
causing the fraine-holder to spring open slightly. The two glasses 
being oblong and lying crossed, it is easy to add a drop of liquid 
during compression. The compressor can be reversed, and in that 
case rests on the three small pillars, which are high enough to allow 
the milled head of the screw to clear the stage. 

The trough is a larger live-box differently constructed. 
‘The form that has proved one of the best up to our own day was 
introduced by Mr. Lister in 1834, and is well known. It is depicted 
‘in fig. 261, being formed of slips 
of and a loose were 
tal ‘of glass equal to the 
feline of the trough, 50 
that it may be moved frecly 
within it, also a slip of glass 
that will lie on the bottom and 
All it, with the exception of the 
thickness of this loose plate. 
To use it, the slip is put upon 
the bottom, the looxe plate is 

laced in front of it with its 
bottom edge touching the inside 
‘af the front glass, a small ivory 
wedge is inserted between the 
front glass of the trough and the upper part of the loose ver- 
tical plate, which it serves to press backwards; but this pressure 













Fro, 262. 


cemented a piece of cover-glass. The cover plate is n 

two bottom corners, and at the two top corners are formed a 

couple of projecting ears. In orler to use this apparatus it must be 

tnd | flat upon the table, and filled quite full of water. The object 
+ Watch-spring or other elastic metal should not be sed on account of oxidation. 











orifice having closed by the forefinger, until its 
bern bere above the oy ctea teee tangents 
the liquid Ceasrfarneeec aca aa 
a phe ably carrying the object up with itj and if this. b 
on 
een eee eee 


i 
E 
i! ? 
: 


ayrings 
the pattern ited in fig. 264, and 
of about double the dimensions, will be 
found extremely convenient. When 
S or firmly hel hepreen Soa Sote and 
—Di =“ slaxe Mddle fingers, an @ thumb is, in- 
a ae cok Se ae anuntid into the ring at the summit of 
the piston-rod, such complete command 
is gained over the piston that its motion may be ated with 
the greatest nicety ; and thus minute quantities of fluid may be 
removed or added in the various operations which have to be 
performed in the preparation and mounting of objects ; or any 
minute object may be selected (by the aid of the simple microscope, 
if necessary) from amongst a number in the same drop, and trans. 
ferred toasepurate slip. A set of such syringes, with points drawn 
to different degrees of fineness, and bent to different curvatures, 
will be found to be among the most useful ‘tools’ that the work- 
ing microscopist can haye at his command, It will also be found 

















CHAPTER V 
OBJECTIVES, EYE-PIFCES, THE APERTOMETER 


Tr is manifest that everything in the form and construction as well 
eee eka feed pany efficient, the special 

is exists for, and to more nt, ial work 
of the objective, i ae lens combination, which constitutes 
‘the basis of the opti properties of this instrument. 

The development of the modern objective, as we have already 
seen, has been very gradual; but there are definite epochs of very 
marked and important improvement. Our aim in the study of 
objectives is practical, not antiquarian, and we tay avoid elaborate 
researches on the subject of non-achromatic lenses, and raflecting 
specula, which have been sufficiently indicated in the third 
of this volume. We may also over the earlier attempts at 
achromatism ; the trie hy the modern objective begins from 
the time that ite achromatiam had been finally worked aut, 

The first movement of a definite character towards this obj 
was made, it has been recontly shown,' so a as 1808 to 1811 by 
Bernardino Marzoli, who was Curator of the ‘ical Laboratory of 
the Lyceum of Brescia, Mr. Mayall di a reference to thia 
effort to make achromatic lenses, and through the courtesy of the 
President of the Atheneum of Brescia discovered that Marzoli was 
an amateur optician, and that he had taken tie 8 interest in the 
application of achromatism to the microscope, and that « paper of 
his on the subject had been published in the *Commentarj’ for the 

1808, and that he had exhibited his achromatic objectives at 
Milan in 1811 and obtained the award of « silver medal for their 
merits under the authority of the Istituto Reale delle Scienze of that 
city, One of these objectives was found to have been coatiginaaly 
presorved,’ and was generously # Cee a in 1890 to the Royal Micro- 
scopical Society of London. ith it was forwarded the ‘Proceso 
Verbale,’ or official record of the awards, notifying Marzoli’s exhibits 
and the award of a silver medal, and the actual diploma, dated 
August 0, 1811, signed by the Italian Minister of the Interior. 

larzoli's objective was 4 cemented combination, having the plane 
side of the flint presented to the object ; and if this was a part of 
the intended construction, of which there appears small room for 
doubt, Marzoli preceded Chevalier in this, as we shall subsequently 
see, very practical improvement. 
1 Journ, Roy. Mic, Soe, 1990, p. 420, 


















‘he i not confined | 
jectives ; and in com two achromatics, 
‘pert hepa thou vs 

its worth—that T hope will lead to the acquisition of 
power greater than could ever be reached with one 
At this time Professor Amici, 


have constructed objectives of ‘aperture 
tat of Chai eel Lon 

’ wil specimens 
work, which produced a most favourable im- 
pression, and subsequently he made an objective 
of d-inch focus. 

time; in this country, Mr, Lister 

aboutan important epoch in the evolution of 
achromatic obj by the discovery of the 
two aplanatic foci of a combination. It had 
occupied his mind for several years, bat in 
January 1830 9 very important was read 
to, and published by, the Royal iy, written 
hy him, in which he points out how the aber- 
rations of one doublet may be neutralised by « 
second. 

As the basis of a mit objective, he 
considers it eminently desirable that the flint 
lens shall be plano-concave, and that it shall be 
joined by a permanent cement to the convex 





lens. 
Fis, 20%.—The two For an achromatic object-glass so constructed 
eet tinction he made the general py secure ge cies 
on one side of it two foci in its axis, for the 
rays proceeding from which the spherical aberration will be truly 
corrected at a moderate aperture ; that for the epace between these 
two points its spherical aberration will be over-corrected, and 
beyond them either way under-corrected. 

‘Thus, let a, 4, fig. 268, represent such an object-glass, and be 
roughly considered as a plano-convex lens, with a curve, a ¢ 6, 
running through it, at which the spherical and chromatic errors 
are corrected which are generated at the two outer surfaces, and 
let the glass be thus free from aberration for rays, fd, 69, issuing 
from the radiant point, 4 Ae being a perpendicular to the convex 


' ' Penetrating meant’ reselving" power in those days; he alludes, therefore, to 
increase of aperture. 














306 OWECTIVES, EYE-PIECES, THE APERTOMETER 
English makers, and undoubtedly carried the palm both here and on 
ves. 


the Continent for the excellence of his ob 
epeuncsarten 
» 55° three pairs, 1884. 
i: S hj 1836, 
© Ge} tiple front and two double backs { 387)" tasters forms, 
i ° oe Ee ve ewline 
we Te: ” ” mae) 
‘Examples of these old lenses are extant and in perfect 
tion, and Pareculenl thesataineeoraralbelaiiret <oneeaent ee 
sip cee acy ne Re een ea eee 
= An example the construction of the inch 


ly 

= corrected the errors of spherical and chromatic aber- 

yeenibination’ by ration that the circumstance of covering an object 

Andrew Ross, with a plate of the thinnest glass was found to dis- 

turb the corrections ; that is to say, the correo- 

tions were so relatively perfect that if the combination were adapted 

to an uncovered object, covering the object with the thinnest glass 

introduced refractive disturbances that the 

of the objective.’ 

Lister’s pay of 1830 


other There was 
n cxallignidesia in on 
L-shaped slot to limit the 
amount of movement ; for 
uncovered objects the front 
combination was drawn 
Fio, 270.—Section of adjusting object-glass  Outand the pin was turned 
into the foot L ; and for 

covered objects the combinations were closed © to their limit. 
Subsequently this arrangement was modified by the introduction 

1 Vide Chapter T. 











be 0-18 mm. thick, the correctional collar should be set to the 
division marked 


018. 

In on the contrary, the divisions are ‘ical, 50 
‘that the has to discover for himself the te 
‘It is not to be supposed, however, that the method is un- 
scientific, for when an ‘becomes expert he would never for 
eae rary ing by any other indication than that 


pple cele er ii a 
object, always, by the quality of the image he obtains, bring the 
correction to within the merest fraction of the same position, 
‘the correction collar and its divisions are never looked at until 
desired image is obtained. 

‘The fact that the over-correction caused by the was 


discovered in England, and that means were at once for its 
correction, while no similar steps were taken on the Continent, is a 
suflicient evidence of the advanced position of this country in practical 
optics at that time. 

This subject of under. and over-correction ia ons of large import- 


ance, and it may be well at this point to enable the tiro to clearly 
understand, by evidence, its nature, al th whet it is has been 
fully shown in Chapter I, Take a single lens, the field-lens of a 
Huyghenian eye-piece will serve admirably, and hold it a couple of 

from a lamp flame ; the rays passing through the peripheral 
portion of the lens will betscnt byrecparinientie Liew one to be 
brought to focus at a point on the axis nearer the lens than those 
passing through the centre. This is wnder-correction. The same 

‘iment should be repeated with te ee site and the convex 
side of the lens alternately turned to flame. In the former 
case, when the image of the flame is at its best focus, it will be sur- 


E 


rounded by a coma, and even the of the flame wl 
focus will lack brightness, But with the convex side 
Hame it will be found that in the image on the card 
greatly reduced, and the image of the flame brightened. 
son for this is, as already stated, that the spherical aberration is 
ca times as great when the convex side of the lens is towards the 


eid 
al 


ecard, 

‘The practice of these simple tests will be most instructive to 
those unfamiliar with the optical principles on which an objective is 
constructed. They make plain that an over-corrected lene ia one 
tohich brings its peripheral raye to a longer focus than its central. 
But a cover-glass produces over-correction, therefore the means 
employed to neutralise the error is by the under-correction of the 
objective. If, however, the objective employed should be unpro- 








i of : to 85°, or “68 
N.A.; and a y-inch ‘ive to 135°, or “93 N.A. OF this 
eel that it was ‘the | pencil that 
could through al 

Ty obo object gloss wee with a triple back combination ; 


back | 

tion, ‘by Hister but it was not the result of intended construction ; 

ke it was a fortunate combination the real value of 
which was neither understood nor appreciated, and as a consequence 
its existence was evanescent. 


front ; the combination is seen in fig. 273, which it will be seen is a 
simpler construction, but this did esi ed least the ieee 
oon jus ently, how- 
‘ever, the form was on the tinent for 
low-priced objectives, which led to a reduction of 
the cost of English objectives of the same con- 
struction. b 
Manifestly, the single front lessened the risk 
Fae of technical errors, but we have never been able 
yet to find a single front dry achromatic objective 
ame = sae which has shown any superiority over a similar 
eyo one ing a triple front. 

single front employed with two combina- 
tions at the back was the form in which the celebrated twater- 
immersion objectives of Powell and Lealand were made. It was by 
one of these that the strie on Amphipleura pellucida were first 
resolved. Indeed, what is known as the water-immersion system of 
objectives, devised by Professor Amici, was the next advance upon 
the old form ; but it was an advance the optical principles of which 

‘were certainly not at the time understood. 

Tn Paris, ski and Hartnack brought these objectives to 
great perfection, and were enabled to take the premier place against 
all competitors at the exhibition of 1867. The next year, however, 
Powell and Lealand adopted the system, and in turn they distanced 
the Paris opticians and produced some of the finest objectives ever 
made, Their ‘New Formula’ water-immersions were made after 
the fine model of Tolles referred to below, and had a duplex front, 
a double middle, and a triple back. In 1877, when water- 











glass of the front lens, the rays of light passed through what was 
essentially a peceabait airs path across from the 
halsum-mounted object to the front lens ; and a homogensous system 
of objectives took the place of the previous water immersions. 
jis was the first great step in advance in optical construction 
und application following the of Abbe. 
As often happens’ in matters of this kind, there had been an 


ws 1844; but it is very apparent that Amici employed the oil of 
wniseed without any clear ie of the principles involved in 
the homogeneous system ; being wholly unaware of either the increase 
of 1] involved or the cause of it, But this cannot be said of 
Tolles, of New York. We have pointed out that as early as 1873) 
he made a yy-inch, and subsequently in the same ® }-inch 
ches, each with a duplex front to work in soft. and with 
a N.A, of 127. These objectives were examined by the late Dr. 
} Vide Chapter If. 2 Mid. 

3 P.27; also Journ, Roy. Microsc. Soc. vol. ii. 1879, p. 267. Chapter T, 





314 ‘OBJECTIVES, EYE-PIECES, THE APERTOMETER 


Feet entiplh Duce rege ee cena ti pe Set allan 
tormediate zone, they will not be combined in the peripheral and 
the central of the . 

‘These it has pointed out,! arise from what is 
known as the irrationality of die spectrum. To correct this we have 
seen that Drs. Abbe, Schott, and Zeiss directed their attention to 
the devising of vitreous com; which should have their 
Lope 2 agar ee eee a ee 
Only by these means could the outstanding errors 
ch ecenesanl be corrected. 


‘objectives entirely cleansed of the From caleu- 
lations of @ most elaborate and exhaustive made by Dr. Abbe, 
objectives are made hy cae which not only combine three parts of 
the spectrum instead of two, as formerly, but which are also aplanatic 
for two colours instead of forone. This higher stage of achromatism 
pre of thi seen) apochromatic objecti 
the i an ‘ic objective 
an eden Zheis disoa he te S16, chide ellinanienoae 
di mutic, but sufficiently illustrates the elaborate corrections 
which the perfect results given by these objectives are i 
But, in addition to their of construction and the speci: 
glass of which they are composed, it is now known that they owe 
touch of their high quality to the use of fluorite lenses amongst the 
combination. Fluorite is a mineral which has lower refractive 
dispersive indices than any glass that has 
Ss ba compan vd hereto by ty nr i 


i 


nl 


the optician can reduce the 
matic aberrations greatly below that reached by 
achromatic combinations of the known type. 


: 


It isa somewhat depressing fact that fluorite 
=! is very difficult to procure in the clear condition 
oO needful for the optician, but from what we have 


seen the optician can do in the manufacture of 
Tivnochcomans ao BIAS WE ay hope that an equivalent of this 
bination. mineral in all optical qualities may be discovered. 
The medium for mounting and immersion 

contact has, of course, to be of a corresponding refractive and 
dispersive index in all objectives of great aperture, and it is insisted 
by Abbe that the glass of which the mount is made, both slip and 
cover, must, when the limit of refraction by crown glass is passed 
by the objective, be of flint glass. This he ts as a sine non 


in the case of the new objective just by the house of Zeiss, 
and a specimen of which has been generously given by the Firm 
to the Microscopical Society, This glass has a numerical 


+ Chapter T. ? Chapter IL. 


= 





be erga ne have (fig 277, in the 

we 

zone two ‘of the s. as: + 30 = 70, andone 
in each of the other zones is also. to the same say 


Pa eA eles “in th ajochrmnt ystom, bw 


ever (fig. 277, 2) we find in the 
eat iia pierre 
» 40 + 30=70. Thus an apochromatic 
ene te 4 To 38D, 
Maton etn dient ealjers ie wil Weare thas this. 
anon 


40, 
ee etal ee aon. 

By ER lene 
rk a sane, fleet gimp tt point of 
‘vast gain of system. 

This interesting & note ae wie the microscope in its earlier 
form took its powerful position by borrowing achromatism from the 
telescope, it has now led the way ee romatised state, which 
without doubt it will be the work of the optician in constructing: 
the telescope of the immediate future to follow. 

We would the reader to bear in mind in the of 
objectives that, whilst the vitreous compounds with which Abbe's. 


constructed, yet it does not means that because an 
pi eleraemnpeerten 

ie must 
preorder scr rely a pst 


mis~ 
nomer. It is another feature of these objectives, which it is import~ 
ant to note, tat toe are so constructed that the upper focal points. 
of all the ives lie in one plane. Now as the lower focal points. 
of the eye- oc are aly er cc pat, foliar tba er kaeperpas 
piece or whatever objective is used, the optical ae will 
remain the same. 

Sa Abbe has found! that in the wide-a 

Coe paw there is an outstanding error which eee pes as 
removing in the objective alone, but, as we have already 
anaes this is left to be balanced by an over-corrected eye-piece, 
As this peculiarity ins only to the higher powers, a correspond~ 
error had to be tentionally introduced into the lower powers in 
that the same over-corrected eye-pieces might be available for 
use with them, 

It appears worthy of note in this relation that one of the best- 
forms for the combination of three lenses ix that known as Steinheil’s. 
formula, which consists of a bi-convex lens encased in two concavo- 
convex lenses. It will be observed by reference to the figure illustrat— 

+ Chapter IL. 





i 


erg igecymnepugerenemn emyee 


ue 
ef 
E 
ag 
3 
i 
# 
3 
i 
Le 


2a 
if 
i 
LE 
i 
Lie 
i 
fe 
ip 


5 

i 
i 
i 
a 


r 
fF 
i 
i 
HE 


Now change the objective for the 16mm. 3 N.A. (=, but 
with the same aperture). Nothing more is to be seen 5 
dexterous mani ‘ion cannot bring out a single fresh detail; the 
resolution is in no sense carried farther ; the cut suctorial tubes 

in fact, in our judgment, better seen with a lower power, while with 


by ene *aisthn wes Sten compared with 
eo a distinct ret jon in every sense 
pemans by the 1 inch when both are equally well made 
and have equal apertures, viz. 3, But. all this, whatever 
may be done by the 16mm. -3 N.A. can be accomplished in an 
ually satisfactory manner by removing the 12 gia p and re- 
it with practically no other alteration by an 18 eye-piece ; 
and still higher results can be obtained without the slightest detri- 
ment to the image by using an eye-piece of 27. 

Not less interesting and convincing will it be to examine the 
same object with a 12mm. ‘65 N.A.(=4-inch), and an A Zeiss 
achromatic of ‘20 N.A. (= $rds inch) using a 12 eye-piece. ‘Those 
who may still retain some conviction as to the value of ‘ low. 
glasses to secure penetration’ can want no farther evidence 
such « simple experiment affords of its entire fallacy. 

For those who prefer it a trae Hsbslogieal object may be selected. 
We choose a portion of a frog’s ler treated with nitrate of 
silver, in which are some convoluted vessels, enclosed in a muscular 
sheath which had contracted. 

‘This object is presented by photo-micrograph in 7 and 8 of 
the frontispiece. In fig. 7 the vessel in the frog's bladder is seen 
by a Zeiss A -2 N.A., magnified 140 diameters. The object of the 
photograph is to expose the fallacy which underlies the generally 


: 
2 
z 
: 
e 
; 
Hi 
a 
: 

Hl 
3 
e 
E 











‘inch of 60° or “5 N.A. will not suffer comparison of the image it yi 
with that of an apochromatic 4-inch of 65 N.A. 
peegerink penal on sls wake question, then, it would be the 
utmost folly CD ee 
4 P . 


from 1 inch (24 mm.) to }-inch (hs mm. “95 N.A.), and more 
recently d-inch. They are most perfect and efficient series of 
objectives ever pl in the hands of the worker ; and unless 
English lenses on « truly apochromatie principle and equal quality 
are produced, it must be to the detriment of either the opticians 
or the workers of this country. 
Nor need it be supposed that the production of objectives 


is provided by the production of two objectives by E. Leitz, of 
Germany ; they have lately come into our hands ; they are but 
semi- tic. The one is low, having an initial ev of 14, 
with an aperture of 30° ; the other is practically a j-inch of “88 N.A, 
‘The low power has surpassed every achromatic of its kind we have met 
with, and the higher power can, without hesitancy, be spoken of as an 
exceedingly good glass ; nevertheless the price of these two objectives 
is together less than the price for the lower power, if made 
in England on achromatic principles, would certainly be! Yet 
Reichert has even su this, and we feel that we be doing 
@ great service to students of small means in calling their attention 
to the following remarkable and low-priced objectives ; Leitz No, 2 
+ Chapter I. 





322 OBJECTIVES, EYE-PIECES, THE APERTOMETER 
Jens being three times that of the eye-lens, the diaphragm being in 
focus. 


Another negative iece is that known as the Kellner, or 

ic. This consists ote bi-convex field-glass,and an achromatic 

doublet meniscus (bi-convex and bi-concaye) eye-lens. 4A vertical 
section of one so constructed ia seen in fig. 279. These eye-pieces 
usually magnify ten times, and the advantage they are supposed to 


ive consists in a large field of view ; bat are not good in 
Pn alaiseeprentne then take in aud of view greater thantbe 


Fro. 278—Huyghenian eye-pieee. Fro, 279.—Kelluer eye-pieee. 


objective can stand, and as a rule even the contre of the field will not 
bear comparison in sharpness with the Hayghenian form, 

Tt is a suggestion of Mr, Nelson’s that a crossed convex 6 : 1 
field-lens and « meniscus and concave-convex doublet eye-lens might 
work well for this form of eye-piece, 

Positive aed eon the early compound microscopes the- 
eye-pieces were all positive ; that is to say, they consisted of a single 
hi-convex eye-lens and no field-glass, The detinition with this must 
have been most imperfect ; the addition of a 
field-lens, though it were a bi-convex, not in 
the correct ratio of focus, nor the theoretically 
best distance, must have been considered a 
great advance, 

In this way matters rested, however, until 
the theoretically perfoct Huyghenian form was. 
devised, Nothing has yet displaced this com- 

Fro, 280. bination or successfully altered its formula 
Object-lasses have been used as eye-pieces and 

all forms of Joups or simple microscopic lenses have been employed 
for the same purpose, Solid eye-pieces have also been cna both 
in England and America, but with no results that surpassed a well- 
made Huyghenian combination; but the best form of all of the 
combinations which have been tried by us as positive single eye- 
pieces are the Steinheil triple Joups; a section of one of these is. 








+ It fs a curious fact that in pructice the usual formula for the Hayghenian ayo 
piece is radius of field-lons terion that of eyelens, and the distance between them. 
‘equal to half the sun of their foci, 





But 
that 12 is the most eek Aeros 
pensating ¢ye-picce is | oul from 
eat cueneees » The 4 is 
‘too low, the 27 is too i the S and 
18 are near the - Papa iter the advantage in 


royale erent RTOS) ee AEN pre et 
ie to or 
in many senses more useful, and would offer facilities in application 
not secured by the series of Abbe now in use, 
Bateerteres to give further emphasis to the fact that this con- 
struction of eye is not oly casenteli 4 Whi amet wae st 


but 
peareaate ste Ca 1 my be noted that the & 12 
sind 1s eines forthe sot tae ae tical with 12, 18, 27 for 
t 


The jection is mainly intended for photo-micro- 

qa tne ieeaial ies Arawak and exhibition purposes, 

is a negative, with a single field-lens and a triple projection-lens, 

proj -lens is fitted with a spiral arrangement i 

that the diaphragm which limits the field may be focussed on to the 

papas gt eh ho io tise pe esl i detion 

= “Te may not bo genorally known that good photo-mierographs 
may ni gene own can 

be obtained by Vy prieton with the oninary compensating working 

eyes 1is is a fact worthy of 

saat verge practical yan ae if we erpea & laps rn 

locus the compensa eye-pieces when wu: 
the and the short body. ae 











Fioens of Bye-peces for long Boy. 

Powers 5 »| 2 4 8 1g 18 an | 
Foousinmm. .| 135 675 337 225 15 10 

» dnches.| 68 | a6 | 18 | ge | so | 20 ' 














Foows of Eye-pleces for short Body. 
1 2 4 6 

iso | 9 | 45 | 0 

ros | 954 | 1977 | 118 





8 
225 
“88 


| Power. Sry 
Foous in min. 
» inches . 





12 18 
15 w 
“59 3 


Projection Bye-pieces.—2 for short and $ for long hodics =90 mm, or 64 
inches} 4 for ahort and ¢ for long bodies =45 inm, or 1-77 in, 


Special Eye-pieces.—The most important of these, the micrometer 
eye-ynece, we have already considered, so far as its application to 
micrometry is concerned.! Its optical character may 
considered here. If it is a negative eye-piece the micrometer ts 
in the focus of the eye-lens, but if a positive combination it is placed 


1 Chapter IV. 


























i 
: 


(it 
z 
: 
i 
A 
i 


= 
a 
i 
lL 
F 
i 
2 
; 
x 
ig 


u 
4 
: 
ie 
& 


4 
iy 
i 
i 
i 


a met ‘wich is at leert acco =f 

in ordinary tive microscope objectives, if tested 
their peeeee simply subjected $0.8 oomparine. of 
ance with other lenses upon the same * 7 

‘The relative excellence of the image seen each Jens 

however, depend ina great part upon fortunate illumination, 
not a little bee the experience and manipulative skill of 
server; besides which any trustworthy estimate of the 
of the lens under examination involves the equsideration at a 
test-object, as well as the magnifying power and aperture 
objective. It is knowing what is meant by a ‘critical image,” 
being able to discover whether or not a given objective will yield 
Clearly all tests of optical instruments, which are not eapable of 
numerical expression, must be comparative. Magnifying power can 
be measured numerically ; it is not comparative. In the same way 
resolving power is mathematically measurable ; 80 is penetrating 
power, But definition and brilliancy of image, and evidence of 
centring, can have no numerical expression ; they are consequently 
comparative, 

‘he structure of the test-object should be well known, and the 
value of its “markings '—if intended to indicate mii ical dimen- 
sions—should be accurately ascertained, care being taken that the 
minuteness of dimensions and general delicacy and ion of the 
‘test-object should be aday to the power of the lens, A fairly 
correct estimate of the relative performance of lenses of moderate 
magnifying power may doubtless be thus made by a competent 
observer; but it ix not possible from an; comparisons of this kind 
to determine what may or ought to be the ultimate limit of optical 
performance, or whether any particular lens under examination has 
actually reached this limit. 

Assuming the manipulation of the instrument and the illumination 
of the object tobeas perfect as possible, and further that the testobj 
has been selected with due appreciation of the requirements of 


: 


28 8. 
Bree eee 








328 “OBJECTIVES, EYE-PIECES, THE APERTOMETER 


Tn any combination of ee rare 

ess and accurate as ils of light 
Beeps i aa Teel Ata. setae ood 
function will be best ascertained by the course of : 
pencils upon different parts or zones of and 


This arrangement places the pencils of light in their most sensi- 
tive position sl exponent iy my ing defect in corre- 
tion, since the course of the rays is such that the pencils meet in 
the focal plane of the image at the widest possible angle, As many 
distinet images will be perceived as there may be zones or portions of 
the front face of the objective put in operation ny 
light. If the objective be perfect all these im jend with 
one sett oes ia atin tclenn colonies icture, Such a 
fusion of images into one is, however, prevented by faults of the 
image-forming process, which (so far as they arise from i 

aberration) do not allow this coincidence of several images from 
different parts of the field to take place at the same time, and (so far 
as ben arise from di jon of colour) produce coloured fringes on 
the edges bordering the dark and light lines of the test-ol and 
the edges of each separate image, as also of the corresponding oo~ 











330 «= OBJECTIVES, EYE-PIECES, THE APERTOMETER 


in pina dean fei Abe's dm this 
upon a short. tube, which fits in the rotating sub-stage. 
Ont sides of this tube, and at a distance from the lower lens 
dc ge Ra TRE appa so pean talons ey 


| 
i 
i 


il 
bar 
I 
F 
HE 
; 
b 


i 
i 
| 
i 


Sie Lente 


of the focus of tive. 

When an instrument is not ided with a ing sub-stage, 
it is sufficient to mount the on a piece of tubing, which 
aise ernpeee always provided for the diaphragm on the 
am side of the stage. 


Card diay for iment may be the top of 
a thin picee at tae open a bh ends} made to lide tale that 
which carries the lenser, and removable at will. By 


Fro. 288. 


‘The test-plate consists of a series of cover-glasses, ranging in 
thickness from 0:09 mm, to 024 mm.,silvered on the under su » 
and cemented side by side on a slide, the thickness of each bei 
marked on the silver film. Groups of parallel lines are cut thi 
the films, and these are so coarsely ruled that they are easily resolved 
by the lowest powers ; yet from the extreme thinness of the silver 
they also form a very delicate test for objectives of even the highest 





332 OBJECTIVES, EYE-PIECES, THE APERTOMETER 


having once centred the light and the condenser, we hold, with 
deere to Dr. Aby tha the Tight shld aco 
soniched 9 baka oblualky "oat det yloaa te fatert 

We balers thas tls thou Ue scoured alley Uf the woramect of 


the 

Foor i cient eet 
foe . 

the | her = co! by. placing 

mirror 80 far laterally that its edge is in the line of the optic 

axis, the incident cone of then onl) PCT 

‘rae abebasaipestive; lp roa teacs ths of the 

and the character of can be easily esti 


When from practice the eye has learnt to recognise the finer: 
differences in the quality of the outlines af the image, this aethod 
of investigation gives very trustworthy results. Ditferences in the 
ickness of lasses of 0°01 or 0-02 mn. can be recognised with 
ajectives of 2 or 3 mm. focus. The quality of the image outside 
the axis is not dependent on spherical and chromatic correction in 


ze 


view arises, as a rule, from unequal ification of the different. 
zones of the objective ; colour-bands in the peripheral (with 
good colour-correction in the middle) are always ea by unequal 
magnification of the different coloured images. Im) tions of this 
kind, improperly called * curvature of the field,’ are 4! ated ail 
or less extent in the best objectives, when theiraperture is ble. 

‘Testing an objective does not mean seeing the most delicate 
points in an object ; it rather means the manner in which an object 
of some size is defined. 

A test for low up to } of 80° or N.A. “65 is an object on 
a dark ground, Nothing is so sensitive. Ono of the Polycistine 
because it takes light well, is good. For higher powers a coarse: 
diatom, a Triceratium jimbriatum, is excellent; for unless an 
objective is well corrected the image will be fringed and surrounded 
with scattered light, and the aberration produ the cover-glass. 
is plainly manifest, and by accurate correction can be done away. 

Error of centring is one of the special defects of objectives 
which the Abbe method of testing does not cover. But if we 
a sensitive object in a certain direction, and when the best adjust- 
ments have given the best image rotate that object through an angle 
of 90°, only a well-centred objective will give an unaltered image 

shout. If not well-centred it will at certain parts grow 

fainter or sharper. The most useful image for this purpose with 
medium powers is a hair of Polyxenus lagurus mounted in balsam 
(frontispiece, fig. 6). 

For higher powers nothing surpasses a podura scale. In this. 
particular it has always been of great value to opticians. Tt should 





334 OBJECTIVES, EYE-PIECES, THE APERTOMETER 


artes 
Se eljeniva ticen the apalearaid 60, what 
mgt AT srk 


needful is to find 
of 





i roecicoartice bsp tes sines, 
3 jek ily gos Sa he A 

tay E oy of a Raises whose angular 
opera = 


here = 1-33, the refractive index of water ; and w, or half 44°, 

in oh, Sine 22° trom tables = 375, which mlipied by 1:33= 5 
Le Motil Sola Ne hes 
rey pett the gee an oil-immersion objective having 

nthe ve index of oil, which is equal to that of crown 
Ceaemeere w= 19} and sine # from tables = 829, which multi: 

= 5. 

Ba toes thes a a jective of 60°, Rh ie 
44°, and an oil-immersion o! bd * all have the same N.A. of “5, 

‘Tt will be well, perhaps, to give the converse of this method. 

iv. Ifa dry objeetive 5 .A., what is its angular aperture ? 

Here because n sine w= *5, sine w= a the objective being 
dry n=1, therefore sine u=°5. Opposite “5 in the table of 
natural sines is 30°; hence v= 30°. But as wis half the angular 
aperture of the objective, 2u or 60° = the angular aperture required. 

v. eae is oe angular aperture of a water-immersion objective 
whose =" 


Here n= 1°33, n sine w =-5; sine w © = 376 > 
22° (nearly) from tables of sines; .*, 2u = 44°, the angle re- 


5 








. What is the angular aperture of an oil-immersion objective 
of 5 NAY 
ca B 
Here n= 1°53, n sine u =°5, sino « =) = i= +320 ; 


u = 19}? (by tables of sines) ; and 2 = 38}, the as 

Wa'aay ve further by a simple hinstetuiet pairs 
nsine u, 

Tn the accompanying diagram, fig. 285, let »’ represent a vessel 
of glass ; let the line Abe perpendicular to to the pl ie the water 
10) } suppose now that a pencil of light impinges on the surface of 
the water at the point where the perpendicular meets it, aoaktoaige an 
angle of 30° with the Pols se ba This pencil in 
sae will be refracted or bent towards ihe pe Lara 
problem is to find the angle this pencil of Tight w will make with the 
perpendicular in the water. 

‘o do this we must remember that m sine won the air side is 


1 Vide Appendix A to this volume, 





(336  ORJECTIVES, EYE-PIECES, THE APERTOMETER 


other words, and to vavy the mode in which this great truth h 
‘been before stated, the ium pert fra ve 
4s equivalent to a water-immersion of 974°, 


meron ih us is to find the angular 
np “be equivalent to a water- 


vii, oe oy rina ated uw = 90°, sine 90° = 1, w sine w 
=1°33. On the oil side »’ = 1:52 and w’ has to be found. 


hein le Bless Vara uh nie 13) = 875; w'=61° 


eon fate ek beg rh fg 
ae see ten Thos sere oles of 00 ain ot 3 
in in water 84° in oil, have idee the same aperture, and 
ae the same designation of -5 N.A, 
1” io penetrating power of any objective is proportional to 


yecan its illuminating power to(N.A.)? Therefore, if we double 


the N.A. we halve the penetrating power, and increase the illumi- 
maling power four times, 
Tn comparing the penaleaiing and illuminating powers of Rass 
tives, however, care must be taken to avoid a popular error, 
them between objectives of different foci. 

Tt cannot, for example, be said that a J-inch objective of — 
has half the penetrating power of a J-inch of "4 N.A. Neither can 
it be said that it has four times the illuminating power. What is 
meant is that a j-inch of “8 N.A. has half the penetrati eee 
times the illuminating power of a preoress objective of + 

But because ting and Selaasing ‘Lininish as 
uhe square of the foci, inh objective A. has four times 
the illuminating and nearly four times the penetrating power of a 
inch of “6 N. 

The nomenclature, in use before numerical areers ‘was 50 
happily introduced, did not of course admit of comparisons of pene- 
trating and pitemipating powers by inspection ; a: however, is 
manifest advantage, contributing to accuracy and precision in 
important resto 

(3) It may be well, for the sake of completeness, to repeat ' here 
that the ving power of an objective is directly proportional to 
ue numerical aperture, If we double the N.A. we also double the 

pe a tiple and this not simply with objectives of the same 

foci, the ease of penetrating and illuminating powers. Thus it 

is not only true that a 4-inch objective of ‘6 N.A. resolves twice as 

many lines to the inch asa j-inch of 3 N.A., but so also does n 

-inch of 14 N.A. resolve twice, and only twice, os many as & 
-inch of -7 N.A. 

Within certain limits, then, the advantage lies with long foci of 


1 Chapter I. 





ies 
a 
He 
a5: 
si 
a 
in 
i 
iy 
a 
is 
i 


" 
zg 
F 
5 F 


in a direction at right angles to the chord 
band. 


su) that the index of is 
Tenaga seen in the centre of the 
iding screens being dispensed with, rotation of the atage will 
of the flame to travel towards edge of the 
aperture ; rotation is continued until the image of the flame is half 
extinguished by the edge of the aperture, the arc is then read, and 
the same thing is on the other side, and the mean of the 
readings is taken. 

Tf the stage rotates truly, and if the instrument is ly set. 
up, the reading on the one side ought to be identical with that on 
the other. 

Suppose that the sum of the Deri on both sides = 60°, the 
mean reading ix uently 30°, which is the semi-angle of aperture 
‘of the lens in glass. m this datum we have to determine the N.A. 
of the dry 4-inch as well as its angular aperture in air.! 

(i) As » NA. =n sine uv, and # sinew =n! sine wu! 5 
which means that the aperture on the air side is equal to the aperture 
on the glass side ; n = 1 for air; »' = 1-615, the refractive index of 
the apertometer ; «’ is the mean angle measured, which in this case 
is 30° ; and » sine « has to be found. 

Now sine “ (by the tables); n’ sine wu! = 1615 x sine 30° 
=1615 x5 =n sine w=the N.A. required. 

{ii) Again, totind the angularapertureor 2u. As before, m sinew 
n’ sinew’ 1-615 x _ ig. 5ge 

n Re 1 ~ et = 
nearly (by the tables) ; 2u = 106°, which is the angle required. 


i i 








=n’ sine wand sine u= 


* Vide p. 2 etseg. 


vo sine u'= 1-615 x ‘866 = 1-4, which is the N.A. 


. n' sine vu’ _ 1°615 x 866 9 
a, sine te eT nee = 82 
by the tables), 2u = 134°, the angle required. 
\ifest that if the refractive index of the apertometer 
§ the oil of cedar, the mean angle measured is the semi- 
ture of the objective, and its sine multiplied by that 
ex is the numerical aperture. 
be found the more accurate and universally applicable 
easuring the apertures of objectives, as the extinction 
hows presitely when the limit of aperture is reached. 

’s stands lend themselves admirably for use 

tometer. The body being removable the aoe can be 

pe! of the, nose-piece, and any measurement 
itely made. We would advise every microscopist to 
e of this admirable instrument, and to demonstrate for 
perture capacity of his lenses that he may know with 
r true resolving powers. 


‘ CHAPTER VI 


PRACTICAL MICROSCOPY: MANIPULATION AND PRESERVATION 
OF THE MICROSCOPE 


Wrrnovr attempting to occupy space with a discussion of the ques- 
tion of the Wa vary "tobe constr cence, We my 
venture to atlirm that it will be but a recognition of practical facts 
if we claim as a definition of microscopy that it expresses and ix in- 
tended to carry with it all that belongs to the science and art of the 
microscope as a scientific instrument, having regard equally to its 
theoretical principles and its practical working. Hence * ic 

microscopy ' will mean a discourse on, or discussion of, the methods 


of employing the mic: and all its simplest and more 
ay pes in the most perfect manner, ined ake and pat ep ad 
tl ‘ical knowledge and practical experi 


perience. 
On this condition « ‘microscopist’ means (or ab least implies) 
one who, understanding ‘ microscopy,’ applies his theoretical and 
practical knowledge, either to the further Puproreeay and perfeo- 
tion of the instrument, or to such branches ‘ientitic research as 
he may profitably employ his ‘microscopy’ in prosecuting. He is, 
in fact, a man employing specialised theoretical knowledge and prac- 
tical skill to a particular scientific end. 

But a ‘microscopical society’ has a noble raison d'étre, because 
it is established, on one hand, to promote—without consideration 
of nationality or origin—improvements in the theory and practical 
construction of both the optical and mechanical parts of the micro- 

» and to endeavour to widen its application as a scientific in- 
strument to every department of human knowledge, recording, in- 
-vestigating, and discussing every refinement and extension of its 
application to every department of science, whether old or new, 

this sense no more practical definition of a ‘mii 
society’ can be given than is contained in the invaluable pages of 
the ‘Journal of the Royal Microscopical Society’ from the end of 
1880 to the present day; and no better justification for the existence 
of such a society can be needed than is afforded by the work done 
directly or indirectly by it, in inciting to and promoting the theo 
retical and practical progression of the instrument and its ever- 
widening applications to the expanding areas of natural knowledge. 
Tn this Jigerse we propose to discuss the best practical methods 


of using the instrument and its sielieos, the theory concerning 
which has already been discussed, while the mode of applying this 





B42 PRACTICAL MICROSCOPY 


because with this par- 
ticular table it will be 
frequently required that 


‘The accompanying il- 
Iustration (1 DRT), with 





FG, 287,—Mioroncopint’s table. the ay references, 
(Soale, £ inch to 1 foot.) will make quite clear the 
2 Cana fo cilroscope; 2, Cabinet Sor objecta: aes of ae 
jeroscope lamp; 4. Lamp i which we recom as 
&. Stand of apparatus; 0, Book; 7. Large micro: well ax the mode of usi 
+8. Second microscope ; 9. Writi ‘igh me 
10, Wull'aceye ana? uu Tagutimodier. © nt it. 


bed be loyed whol: toe ese spat _ 
seribed is su, to be em wl 
ce ght, Se Reinet pee 
But the mi ist who aims at more than this will require an 
arrangement for dissecting, mounting, and arranging histologi 
and other preparntions, and in some cases a special table for general 
purposes of microscopical biology. These are certainly not essen- 
tials, especially if the work done is a mere occasional oceupation ; 
but where anything like continuity or periodical regularity of 
tion with such work is intended, it will be of great service, 
dissecting and mounting table is indecd of inestimable value to 
those who affect complete order and cleanliness in the accomplishment 
of such work. 

We have found in practice that a table firmly made, with a height 
of 2 ft. 6 in., semicircular in form, and a little more than half 
the circle in area on the outside, with the are of another circle cut 
out from it to receive the person sitting at work—much after the 
fashion of the jeweller's bench—serves admirably. A rough sugges~ 

2 Chapter TV. p, 288, 


LABORATORY TABLE FOR MICROSCOPIST 343 


is given in fig. 288, which presents the of the 
wb sr beth thrid be unoonpny bat at 

drawers ma: not extending more inch 

wader wurfece of th the side B a 





a 
Fro. 243.—Dissecting and mounting table. 


this way all that is needed for dissection or mounting will be 
ireach without moving from the chair; and if by an arrange- 
which most moderately ingenious manipulators could accom- 
each of the articles in the drawers has a fixed place, there will 

difficulty in finding by touch what is wanted. 
pitch pine stained black, or, still better, 

very hard wood finished smoothly, but ‘grey’ 
fhe space in the figure immediately in front of the operator 
‘be cut out to a convenient size and thickness, a thick plate- 
tab whose edges on the right and left sides shall be slightly 
led, so that it may slide firmly into a prepared space cut into 
of the table and occupy this space, the surface leing 
lly level with the surface of the table. This plate of glass should 


tade black on its under side, so as to present a uniform black 
ws. This is often of great value in certain kinds of work. 
Wy useful ise purely white unabsorbent surface, and a slab of 


tpercelain may be easily obtained of the same size and be made 
exactly into the same place. 
a using this table for dissection the arms have complete rest, 


344 ‘PRACTICAL MICROSCOPY 
and lin the figure would represent the position of the dissecting 


cro ta Ca tecen Webs iata eae 
answer 


3 ie aachil ooael otapicl (dilute) for use with the section knife. 
4 is. of mounting media, in suitable bottles, as Canada 
balsam in or xylol, ‘ine, &c, as well as small bottles 
ob peagents:toe ical or ical histology ce. 
5 is a nest of apertures in whi ep mL yea ee ngeeey 
to protect them from dust, while the . mar, ke. be 
hardening on the cover so as to be in a suitable state for final mount- 
Sa A slide way go ‘oven tie| sloping dom Obi on ane RD. Se 
hu 
6 is a stand of cements, varnishes, &c. such as are needful ; and 
7 is a turn-table. 
For the work of dissection, when the subject requires reflected 
light, one of the desiderata is a mode of illumination at once conve- 
nient and intense. Mr. Frank 
R. Cheshire, F.LS. &e., whose 
apie nue = 
ing’ is a wledge 
Pe eta ert ental 


‘Fro, 289,—Mode of i!umMation for have always found admirable. 
dissection. Ti 


= 
i 
e 
2 


Rays of light from a lamp are 

poles by a bull’s-eye full upon an Abraham's prism and 

upon the object. The prism may be mounted on a long 

many-jointed arm and is of most varied ness. A ns 

binocular is, we believe, employed by this gentleman, but it will 
serve admirably for any form of dissecting instrament. 

For the more ral purpose of the private laboratory a plain, 
firm table & feet § inches x 3 feet in area, of a suitable height for 
the worker, should be fitted as follows, viz. : if tiy. 290 represent the 
rough plan of the table, 1 and 2 are gas fittings attached to the main 
to supply blowpipe, Bunasen's burner, ke. 

4 isasmall tube of metal attached to the water main, with a 
tap, and bent in the form of an inverted f, with the attached leg of 
the f the longer. This affords « pleasant stream of water for wash- 
ing dissections kc. ; and if the open end be made with a screw, and 
have a suitably made piece of tubing fitted, to screw on to it, this latter 
may be attached to an indiarubber tube, at the other end of which we 
may fasten fine glass noxsles, which will act as wash bottles of the finest 
bore, und serve with the finest dissecting work. 

Sisa Clee trough for waste, with a perforated aperture, 6, con- 
nected with a waste-pipe, through which the waste water ie, flows 
innocuously away. 

3 represents the position of a Thoma microtome, and A B are two 
well-framed flat slides, which may.be drawn out eighteen inches, or 

4 Journ. RAS. now series, 1887, p. 082. 








348 PRACTICAL MICROSCOPY 


longs of chimney should be 7 inches. Chimney should be 
|. inside. This chimney serves four purposes: Ist, image 
of flame is not distorted by strim and specks common to ordinary 





Fro, a4. 


lamp chimneys; 2nd, prevents reflexion from inner surface of 
chimney, which’ causes a double image of flame; 3rd, prevents 
scattered light in room ; 4th, is not readily broken ; slips can be 
easily replaced. 

' It in very important to remove the metal chimney after use, or at least not to 


leave it on when not in use,since the evaporating paraffin gathers round it and causes 
undosirablo koent when the lamp ix wywin hit 








ive direct and not’ oblique re- 
lexion, the lamp flame, by 
means of a card, is arranged 
as nearly right for the re- 
flexion of the image of the 
flame into the centre of the 
field as may be, and then a 
little movement in one or both: 
milled heads will bring it ac- 
curately into the field. 
We may arrange the micro= 
scope for ordinary transmitted 
light, that is, for light caused to pass ‘eccmngb the object into the 
object-glass, by placing it upon the table, arranged as already 
directed ; the instrument is then sloped to the required position, 
and a condenser, suitable to the power to be employed,! is put into 
the sub-stage. The lamp is now put into the right position, with a 
bull’s-eye, on the left of the observer, The condenser is then, as 
described below (p. 351), to be ‘centred’; when the objective 





Fro, 295, 


1 Vide Chapter TV. p. 24% 








a a 


352 PRACTICAL MICROSCOPY 

Butit (he lame, E-—still contral—rwithin the focus of 
vase tere shin Dy e207 a ‘moving: Ei wlhoue 
‘the foous of B wo got the picture H, while K is tho picture when K is 
focussed but not centred. f 
concavermirror'O (ai. 808) oo that the fame Eeauindtepyined 
9 thnt parallel 


® totally 
different result from what is aimed at, If the concave mirror, ©, is to 
B ‘be of any use in illumi- 


ae 
fel 
He 


7 
ZG 


Fra, 208.—Rewalt of placing fame in principal focus an _ilastration ‘of 
“The method of obtaining critical image with a condenser by 
of transmitted light is shown in fig. 299. Eis the edge of the 
S represents the sub-stage condenser, and F the object. F is 

8 


67* patclnce 

is to say, these are the 
lations which exist when 
acondenser is focussed on 
and centred to an object. 
Let this be understood as 
= the law, and there can be 
the best 


E16, 200.—Mode of obtaining critical image. ing in 


i 


ae 
Ss 

as > fig. 300. aa is the 

plane mirror and, pro 
ee 
E- result may as 
a in tho former case. Tt ix, 
however, slightly more 
5 difficult to set u) Xt will, 
Fig, 800.—Another method of getting critical on the ratiolante preter: 


Nothing can be of more moment to the beginner than to under- 
stand the practical use of the condenser, We must direct the student 














HOW’ TO OBTAIN A ORITICAL IMAGE 353 


as been stated oo ing it in Chapter IV. But the 
should be carefully fully considered. Fig. 301 shows a sub- 
mser, 8, and an objective, O, 


R 
ved on the same point. The 0 
has an aperture equal to that 
ective. Now if the eye- 
emoved, and we look at the sg 
the objective, it will be 


of 

i Figo. 801.—Condenser and obji 
ind igs can De "arama 
wer cut down hy a stop, is seen in fig. 302. Now only 
» back of the objective is filled with light, as at T in the 


1 fig. 301, that therefore the 0 
3; to be full of light. The 
hows the bright image of the g 
flame, and itis in that alone 


ure can be found. If Fro. 802— The same, with tho 
ser be racked either within $perture of the condenser cut 
; the focus, the whole field r 

2 illeminated, but at the same time a far smaller portion 
tive will be utilised. On removing the eye-piece and 
the back lens of the objective, pictures like D, i fg. 297, 
a—D when within, and H when without the focus. 
adition represented in fig. 301 at R and O is the severest 
can can be applied to the microscopic objective ; that is 
ill the whole objective with light and so test the marginal 
' portions at the same time. 


b 
} 


F 


Fro. 308.—Ilamination for ' diffused daylight.’ 


‘© obtain the state of illumination known as ‘ diffused day- 
a the simple mirror when no condenser is used is frequently 

moet inaccurate manner. The correct method of doing 
wn in fig. 303. F is the plane of the object, C is the con- 
ye, the mirror being placed at the distance of its principal 
1 the object. But the manner in which it is usually done, 
tof thought or knowledge, or both, is shown in fig. 304, 

AA 


354 PRACTICAL MICROSCOPY 


where it is manifest that there is a total disregard of the true focal 
point of the mirror and its incidence on the plane of the object. 
From the impracticability of this diagram as a representation of a 
working plan of illumination, we may see at once the importance of 


F 


4 
Fic, 304.—Erroneous method of arrangement for ‘ diffused daylight.’ 
having the mirror fixed upon a sliding tube, so that its focal point 


may be adjusted. 
Tt is also important here to note that in daylight illumination 











Fic, 305.—Light from the open sky falls upon the mirror in all directions. 


a plane mirror gives a cone of illumination, as in fig. 305, when there 
is ample sky-room; but a window acts as a limiting diaphragm, 

In regard to the parallelism of the direct solar raya there is of 
course no question. But the parallelism of that portion of the solar 








356 PRACTICAL MICROSCOPY 


therefore be considered, The extent to which it is 80 far 
as its influence upon the n Seca Wsahely snore oy 
RSE nas ee 3 of the objective when the 


-piece is Fig. the w 
plane mirror i: , and 301, R, when the concave mirror 
ie pe 30 tet thodd study these experiments. 


by i e 
a Ted cart saalsbd Gt Clvaalsaltag dy Bitete Hoi pPoad ots 
the obj Loree ie woes ete Hema hori 
means of that shown there is not enough 
the Re sTigesibatd even whéc tha Cink ce to Batralsa abe Of 
” od 


Ss 


. $07, —I k of 
Pits sea e 
‘mirror are used, 
course it will be understood 
that for the dark-ground re- 2 oa 
sult a scien Hops inserted 
beneath the sw con 
ey one Fic, 308 —Ilumination for dark ground (withe 
It has been shown by Winn Descent ten ccedoaoen), 
many illustrations on many subjects that certain results in critical 
work can be obtained with the bull's-eye which are not 60 accessible 
without its use. But Mr. T, F. Smith has made this clear regard- 
ing the structure of certain diatoms. 
This, there can be no doubt, is due to the fact that the parallel 
and increase 


& 


rays, sing on the sub-stage condenser, shorten ite focus 
the be i the cone of illumination. It will be noticed that when 
the bull’s-eye is introduced the condenser will need racking-up. At 
the sme time we prefer illumination as in fig. 299 or 300, except in 
cases where illuminating cones of 
& maximum angles are red. 
‘Thus it will be little needed with 
S transmitted light atone when oil- 
immersion objectives aper- 

ture are used, because iuminati 
cones up to "8 N.A. can be obtained 
Ee. with good condensers by the 
€ method shown in tig. 299% But 
hic the microscope is of necessity. 
= dase xagnit ora Gon used upright the rectangular prism 
Fro, 900, Same resalt with conenre Om the plane nkrasie Sate NO 

fig. 300. 

The arrangement at fig. 308 is sometimes useful for photo- 
micrography when it is otherwise impossible to Maminste the whole 
field. But in ordinary cases it is better to contract the fleld than 
use w bull’s-eye, as it invariably impairs the definition. 











358 PRACTICAL MICROSCOPY: 
latter being inclined so as to reflect the beam on the back of the 
sul condenser. 


b-stage 
N kind of and: in the centre of the 
Poin tetat ima natty then tack the condenser until 


its comes 
to the fricerativm, as in fig. 313. Rack the condenser closer up 


Here it happens thut the bull’'s-eye is not in the centre, and it is 
not uniformly led wh ht, a 296, A, but has instead tev 
orencents 


‘This is a case which frequently repeats itself, but it is of course 
not inevitable. The bull’s-eye may be more or less filled with light, 


OO%® 


Fie, $12. Fro, 818, Fig, 84. Fro, 815. 


and may or may not be more nearly centred. In this case we have 
next to centre the image of the bull's-eye to the triceratium by 
moving the mirror, as in fig, 315, 

But it will be noticed that this centring of the image of the 
bull’s-eye does not rectify the diffusion of the light. This will be at 
once done by moving the lamp with attached bull’s-eye ; this motion 
requires to bea kind of rotation in azimuth round the wick as an axis. 
The relative positions of the lamp and bull’s-eye must on no account 
be altered, and it is saterebood that the lamp was adjusted to the 
picture A in fig. 296 by inspection and without the mi A 
very slight movement in azimuth, however, is enough to the 
desired end (fig. 316), and all that now remains is to open the full aper- 
ture of the condenser anc put in the smallest stop ; if this does not. 
stop out all the light, a larger one must be tried; but it is of the 
greatest importance that the smallest stop possible be used, « very 
little difference in the size of the stop making a remarkable difference 
in the quality of the picture, Hence the need of a large and varied 
supply of stops with all condensers. 

On account of some residual spherical aberra- 
tion the condenser will probably have to be racked 
up slightly to obtain the greatest intensity of light. 

Tn fig. 316 the expanded edge of the flame 
covers the friceratium, When the whole 
of the condenser is opened the size of that will 
not be altered, its intensity only will be increased. 
When the stop ix placed at the back of the con- 

denser, only in that part of the field ited 
by the dise of light will the object be illuminated on a dark ground. 
If, therefore, the disc of light does not cover the object or objects, 





Fro, 16, 





360 PRACTICAL MICROSCOPY, 


Tt seems i pepacreeea plete pe ia ca hp dnalenli 
as those who are to use one | eye feel 
Shay maclis ct eng sly Sears prope tel 

ol isa gain to use 
ially with hij of of work 
ge er rg mpgs talon a 


Tt ‘there & is too much ht, 
mas dt! alaristiis piece or pigces of bh this soften: 
am mic a or le s 
the ght and removes the objectionable yellowness 5 4 feature of 
illumination not due to the light from the edge of 
which, as we have stated, is not particularly yellow. Great 
neas is a sign of imy achromatien in an objective. We may 
with precualy the same conditions find the i yielded by two 
yeaa enc ty Mat tae cua aperture differ, in ” Astncacti 


Fe 
LE 
i 
5 
z 
F 


peti 
which i a bright and a white image may nevertheless be inferior 
to the one giving the Aa and dim picture. Thus if the planes 
of the lenses of which the objective is composed are not at right 
les to the optic axis there will be serious defects in the image, 
although it is bright and white. This fault is known in eae as 
an error of centring, which also means the error of not placing the 
axes of the lenses in the same straight line ; s0 both faults are 
described by the same term. 

Tt sh be understood that neither blue glass nor ammonio- 
cupric solution will yield monochromatic illumination. If the es 
passing through these media be examined by the 
yellow, and green will be seen. Some specimens Mant ginal pessidte 
more red than others. Out of a number of samples the best result 
was obtained by using two thicknesses of cobalt ‘pot’ glass, which 
gave two bands in the red. If a greater thickness were used the 
light became too dim. The ammonio-cupric solution merely dims 
down the whole spectrum. When a sufficient thickness of solution 
is used to cut out all the red light, then the light is too enfeebled to 
be of any use visually, and also, what one would not expect, 
photographic exposure is greatly prolonged. 

It would seem that true monochromatic illumination obtained by 
absorbing media does not exist. Neither does the manipulation of 
the source of illumination by means of chemical substances 

rently give satisfactory results. 

Coloured light derived from a polariscope and a selenite is nob 
monochromatic, 

There are two ways of obtaining true monochromatic illami- 








from hire if ;' and he does not conceive that there is any 
ground for expectation ‘that this mixture should come nearer to 
ised by auow i oiting nahi a why 
‘a narrow ax) mina 7 a 

nt, and should receive full pease At the same time 
iMierase of ido acd solid cones is so full of suggestive results that 
we must employ them, with all possible control by other means of the 
omepe tien. present. This is the more a n¢ ity since Mr. Nelson 

n able to obtain the most wonderful results with harrow cones, 
‘true ghosts’ and ‘false ghosts,’ the presence of ‘intercostal 
in the nage of y's exe (1), an any y complex and false i 
with the ut with wide cones he has proved 
these false images cannot be produced ; and that when the pelo 
is reached by a wide cone, the © image is not altered by any change of 
focus, but simply fades in and out of focus ‘as a daisy under a 4- 
inch objective.’ 

Mr. Nelson has photographed all these results, and we have seen 
them demonstrated. When theory and practice are thus at variance 
we must pause for further light. 

If it is required to accentuate a known structure, euch as the per- 

JSorated membrane of adiatom, it can be done by annular illumination, 
which means the same arrangement as for dark ground, but with a 
io be emend large to shut out all the light. This method is not 
to be recommended when a structure is unknown, as it is also liable 

to give false images. It must be remarked that diatom and other 
delicate structure when illuminated with a narrow-angled cone gives 
on slight focal alterations a variety of patterns like a Kaleidoscope ; 
with a wide-angled cone a single structure gives a single focus, ic. 
it goes completely out of focus on focal alteration. en a 
angled and a wide-angled objective are usod a change of pattern only 
occurs when the structure is fine. This practical observation has its 
value and must not be forgotten. 

To properly display objects under a microscope is to ® certain ¢x- 


3 





364 PRACTICAL MICROSCOPY 
save that a cone of small angle, ie. of 0-1, was used for illumina- 
tion. ‘ ‘ 

‘The first alteration which thrusts itself | the eye is the 
doubling of the hairs, which aeons De tooee 
But further, it will be noted that there is a bright line with a dark , 

round the hairs whieh nro preciosly ia foona 3 Vapi ad = 
i present in objects illuminated 
Tnsoficient angle, and it 


cones of it can be easily made to dis by 
widening the cone. Peretti Hoey opr eee 
sharper and , and their become But 
nothing is. but the rather a distinct loss is incurred, by making 
the illumi cone jective cone, 

Peron Savane eae tation of 
the py; a flea by some ing Sources a 
few years be I. Tt was a ial 

aelieetgditas Denar j this shews that it Ss not an 
accidental error, which it it have been if it were merely an 
ordinary object ; it is an error inall PrcceDhy aE, 


proceeding represen 
as being ‘stiff and longish bristles,’ thick at one end and tapering off 
‘to a point. vige toes small ia are Seren ‘minute 
ines’; int wing they are lil ¢ spinous hairs of an insect 
aa have the usual poskst-jolat atthe base. In the ‘stiff and 
i bristle’ is an extremely long and delicate ent, totally 
un a bristle, being not tapered but of nearly uniform thickness. 
The ‘minute spines’ are in reality very curious hairs, and, as far as 
we at present know, unlike any others. They are delicate, lambent, 
bulbous hairs. What they most resemble are the tentacles of a sea- 
anemone, and there are two tubes discoverable which are important: 
and comparatively large objects. There appears to be poe ia 
probability that this interesting object upon the last ring of the body 
of the flea, and known as its ‘pygidium,’ acts as an instru- 
ment.! In the examination of ordinary stained histological and 
pathological sections by transmitted teak unless some very delicate 


int is sought, the condenser should have a stop so that when the 
Pack of the objective is examined the is seen cutting into the 
back of the objective by about « thind. is in some instances mm 


be increased to a half by diminishing the cone, but it is not advi 

to use anything less than a half unless it is absolutely necessary. 
Thus, to put it in round numbers, an illuminating cone "2 N.A, is 
wey, suitable for ordinary work with the apochromatic l-inch and 
& objectives, and one of “4 N.A. for the 4 and 4 and one of *6 N.A. 
for the and }. It isa good plan to have one or two stops eut to 
give special cones, the N.A. of which should be ved on them, 
This subject is one of great importance, as more nine-tenths 


* Micros. Journ, April 94, 1885, ' Pygidium of Flea (E. M. Nelson). 





When # condenser is united by a film of oil to a slij 
i thin thevolt it hy imo conten ete, 


following is a sort in Rennes 
be entirely prevented. 
cover-glass about 02 pater t tk 
has a stri Shellas to oxpredaee: attaeoes 
pest y shellac to one 
iaae' ia otted dite slip, perry ‘anans 
tidked over ede of oe ord Oy he 
only prevents its slipping n, butalso keeps 
the all from creeping out at the bottom, which 
of glass with would be the case if the two edges of the 
b piece eines wip gis coincided.! This is illustrated in fig. 


lide, ik its proper place we have dealt with the 
suitable relation of aperture to power, and 
ae have pointed out the irresistible nature of the 
contentions and teachings of Abbe on the sub- 
‘Slide é# situ on thin slip ject, Here a direct practical presentation of 

with ledge, the matter may be of service to the student. 
Pro. 817. A normal unaided human eye can divide- 
gto inch at ten inches, Consequently a 
microscope with a power of 200 should be capable of showing 
structure as fine as syhyq inch, Now as this power can be made 
up by a 4-inch objective and a l-inch eye-piece, it follows that 
sufficient aperture ought to be given to the $-inch to enable it to 
resolve 50,000 lines per inch, This* will be 52 NA. The inch 

3,8: 6,0. Journal, Norornbes S606, 
in 


reality it will require more, because an axial cone is assumed to be used 
instead of an oblique beam. 





—Seee"""™ 


368 _ PRACTICAL MICROSCOPY 
6. 


Flatness ‘is, in the strict. meani of the term, an 
visible secanentenereet he sadn neue (Tests: For 





obtained, a solid axial cone of illumination equal to at least 


be 
Speen in a of the objective. 

Very low powers (3-, 2-, and 1}-inch).—Wing of Agrion pul- 
= ee 






Cpsianeads |4),—Minute hairs on 
is of blow ponsiltal ( r 
pms on a dark isa most sensitive test; unless 


¢ apertuy 
secondary structure of Deri he apres the fracture the 
perforations. Nanicule ides from cherry field a tee or 
styrax; bacteria and micrococci stained, 

‘Test with a 10 or 12 non Pie and take into account the general 
whiteness and brilliancy of the picture, 

‘The podura scale is not mentioned as a test, as it may be very 
misleading in unskilled hands. One great point in testing objectives 
is to know your object. Care must be exercised to ascertain by 
means of vertical illuminator if objects such as diatoms on the 
cover are in optical contact with the cover-glass. ‘Testing objectives 
is an art which can only be acquired in time and with experience 
gained by seeing large numbers of objectives. 

Tn the manipulation of the microscope it is not uncommon to 
observe the operator rolling the milled head of the fine adjustment 
instead of firmly grasping it between the finger and thumb and 
governing, to the minutest fraction of are, the amount of alteration 
he desires. It is undesirable and an entirely inexpert procedure to 
roll the milled head, and cannot yield the fine results which a deli- 
cate mastery of this part of the instrument necessitates and implies. 
‘To use aright the fine adjustment of a first-class microscope is not 
the first and easiest thing mastered by the tino. 

Beyond the correct and judicious use of the microscope and. all 
its applinnces, there is the matter of the elimination of errors of in- 
terpretation to be carefully considered. 

‘The correctness of the conclusions which the microscopist will 
draw regarding the nature of any object from the visual appearances 











370° PRACTICAL MICROSCOPY 


Be 

Although no experienced mii 
by such obvious fallacies as th seep pe be 
them as warnings to those wl ve still to through 

same education, The best meted of Tearing to" apresa the 
class of ay noes in question is the ben aerate of of 
globules Hi oil in water with that of globules of of 

bubbles of air in water or Canada balsam. This comparison may 
be very readily made by shaking up some oil with water to which: 
a little gum has been added, so as to form an emulsion, or by 
simply placing a drop of oil of turpentine (coloured with magenta 
or carmine) and a drop of water together upon a slide, laying a thin 
glass cover over them, and then moving the cover backwards and’ 





i 


§ Monthly Microscopical Journal, woh. ¥, 1872 p. 1d. 





STUDIES IN INTERPRETATION 371 


forwards several times on the slide, Equally instructive are the 
a Go sheng to in remiss ‘Canada balsam. 
figures which illustrate the appearance at various points 
of the focus of an air-bubble in water and Canada balsam, aon 
fat-globale in water, may be thus illustrated, viz. a diaphragm of 
§ of « mm, being placed at a distance of 5mm. beneath the 
stage, and the concave mirror exactly centred. 
Air-bubbles in water,—No. 1 (fig. 318) represents the different 
appearances of an air-bubble in water. On focussing the objective 








‘Pw. S14. —Air-bubbles in (1) water, (2) Canada balsam; (3) fat-globules in water. 


to the middle of the bubble (B), the centre of the image is seen to be 
very righter than the rest of the field, It is surrounded by 
a ish zone, and a somewhat broad black ring interrupted by one 
Or more brighter circles. Round the black ring are again one or 
more concentric circles (of diffraction), brighter than the field. 

‘On focussing to the bottom of the bubble (A) the central white 
circle diminishes and becomes brighter ; its margin is sharper, and 
it is surrounded by a very broad black ring, which has on its 

one or more diffraction circles. 
Then the objective is focussed to the upper surface of the 


gad 


size, and when ipper part of the objective is in wo 
(C") a small white central disc, brighter than the rest of the field, 
and sharply limited by a broad, dark ring which is blacker towards 


_ ‘These apy ere. gin com ocanl ose NceN Ere aTaee 


which is the broader, and a centre which is the sharper, acconling 
as the objective is brought nearer to the upper 
These considerations, apart from their enabl 
between air-bubbles and fat-globules, and preventing their 
confounded with the histological elements, enable two general 
ora to be established, viz. bodies which are of re 
centre 

when 


ive power than the surrounding medium have « white 

which is sharper and smaller, and a black ring which is larger 
‘the objective is withdrawn ; whilst those which are of less refractive 
power have a centre which is whiter and smaller, and a black ring 
which is broader and darker when the objective is lowered. 

Monochromatic Light.—The same phenomena are observed by 
yellow monochromatic light, except that the diffraction fringes are 
more distinct, further apart, and in greater numbers than with 
ordinary light. 





374 “PRACTICAL MICROSCOPY 


is Lec her But none of the particles he has examined 
are 80 active as. of pumice-stone that upinan 
agate mortar; for these are seen under the 
swarm with an incessant quivering 50 that it is 


Ligier, ita of water for ‘The 
rate of subsidence clays or other ‘icles suspended 
in water thus ef pragttaere np arene 


and sink, so that the liquid clears itself. 
Pedetic motion depends on, that is, is affected by— 
Se ere 
: ‘len. a 
vermilion, of similar size to particles of siliea or gamboge, move much 
ean pee 
. nature igus a 
which have a chemical action on the eubwtancede This 


adhere together and move very slowly. 

But besides the right appreciation of the nature of there 
is the utmost caution required in the interpretation of idity of 
snovement, and kind of movement which living and motile forms a 

The observation of the phenomena of motion under the microscope * 
has led to many false views as to the nature of these movements. 
Tf, for instance, swarm-spores are seen to traverse the field of view 
in one second, it might be thought that they race through the water 
at the sy of an arrow, whereas they in reality traverse in that 
time only a third part of a millimetre, which is somewhat more than 

1 See also the Rov. J. Delsanlx ‘On the Thormo-dynamic Origin of the Brownian 
Motions’ in Monthly Journ. of Microsc, Sci, vol. xviii. 1877. 
* Day Mikroskop, Nocgeli and Schwendener, p. 268 (Eng. eit.) 





376 


kind. 

One of Professor Abbe's experiments on ion phonomence 
proves that when the diffraction spectra of the order are: 

‘out, while those of the second are admitted, the appearance of the 
structure will be double the fineness of the actual structure which 
causing the interference.' 

Upon this law there appears to depend a number of fal~ 
lacies, nagar ned Eom ayaa eer or misin= 
terpretation. At least these appear to us, a ‘ical point of 
view, to be of sufficient importance to need Be egieer ep rn 
ftaller-scxpenibinn of theives Insite regard to them. 

If, for example, figs. 320,321, and 322 may be taken to represent 
& square gratil ving 25,000 holes per linear inch at the foous of an 
objective at P, PD the dioptric beam, P' P? diffraction spectra of the 
first order, and P? P? those of the second order, then if the ve 
is aplanatic all those spectra will be brought to an ident focal 

conjugate ; and the image of the 


grating will be a counterpart of the 

si r Rese. brea poten es 

2 < roup of spectra, it US BUppose 

cana ve to be over-corrected, 

i“ Vo as in fig. 321, then when the grat- 
ip? 


ing is focussed at P the spectra 
the firat order only will be 
Fie, 990, Fro, #22. to the focal conjugate ; the im: 
however, will not be materi: 
affected on that account, as the diffraction elements of the first order 
are alone sufficient to give a trathful representation of the 25,000 
per inch grating. If, however, the objective be mised so that the 
ting lies at P* the diffraction elements of the second order only are 
Fought to the focal conjugate ; consequently by the ieee the 
image will have 50,000 holes linear inch, or double that of the 
original, In other words, placing a grating at the longer focus of an 
over-corrected objective is apparently tantamount to cutting out the 
diffraction spectra of the first order by a stop at the back of the 
objective, 
1 See Chapter IL. 


378 PRACTICAL MICROSCOPY 


When the buck of an objective of ‘83 N.A, shows an arrange- 
ment asin 
then, structure will be invisible, 
St it hp deey ek + +» 40,000 per inch. 
No.9 then the irwetare doe! not iter atl tom £0,000 4 
lo. ” ” ” ° 


No. 5 ” ” ” 
No. 6 » ” 


EN aie ttc Bed rrr alae tee ea dd 
ith : 


Bg 


F 
: 
; 
i 
; 
& 


panese by 

gate cleaning the front lenses of homogeneous objectives ; but 
while these are excellent, especially the former, we find nothing 
better than the simple cambrie we Pa oac 

Two or three good chamois leathers should be kept by the 
worker for specific purposes and not interchanged. Cleanliness, care, 
delicacy of touch, and a pu: to be accurate inall that he does or 
seeks to do, are essentials of the successful oa ra) 

Tt may be noted that dust on the eye-piece can be detected in a 
dim Hight, and can be discovered by closing the iris diaphragm.” The 
lens of the eye-piece on which the dust appears may be localised by 
rotation ; and this should be done before wiping. In reference to 
dust on the back of the objective, it should be observed that if the eye- 
piece be removed, dust sometimes appears to be upon it which comes 
really from the focus of the sub-stage condenser, and is, in fact, not 
on the back of the objective at all. To find this condition, remove the 
light modifier (if in use), for the dust may be on it, and rotate the 
condenser ; else there will be needless and injurious rubbing of the 
hack-lens of the objective. 

With oil-immersion objectives dust or air-bubbles in the oil 
must be carefully avoided. 

If chamois leather be used for cleaning the lenses, it should be 
previously well beaten and shaken, and then kept constantly in « 
well-made box. 





380 PREPARATION, MOUNTING, AND COLLECTION OF OWJECTS 





is 

aire in cutting it ; hence covers should be purchased, eeregalied 
fe the dealers, who usually keep them in several sizes and supply 
any others to order. Save the fact that ‘cover ’ is made 
Messrs. Chance, there is no definite information as to the mode of its 
manufacture and the eae ee upon a it ix most satisfactorily 
produced. Tt would be an advan’ to the microscopist to possess 
information on this point. The different thicknesses are usually 
ranked as 1,2,and 3; the first, which should not exceed in thickness: 
the °006 in., being used for covering objects to be viewed with ow 
pores ; the second, which should not exceed -005 in. in thickness, 

i objects to be viewed with medium powers ; and the third, which 
ought never to exceed 004 in. in thickness, for objects which either 
require or may be capable of being used with high powers. Tt must, 
however, be remembered that the achromatic objectives of great 
power and it aperture (1-5) will require much thinner covers 
than even ive The thinnest glass is of course most difficult to: 





“7 


382 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS: 


Tt is well to assorted measured and cleaned 
till soprnte ebeatoppeceanconierse methylated i 


— 


Fic, 925,—Zoims's coverrglass tenter, 5 
fess On the faces opposite to the respective handles, so that when the 


surfaces so flattened are laid upon and pressed towards each other 
they are everywhere in perfect contact. They should be from two 
to four inches in diameter, and these flat surfaces should 
have very tightly stretched upon them a firm, even-textured, 
moderately thick piece of chamois leather, If covers be sli 
moistened—even breathed upon—and laid on one of these bl 

and pressed down with the other, breath, or moisture applied by a 
stall camel-hair brush to the upper surface of the cover, may be 
applied, and a few twists of these blocks upon each other when 
firmly pressed ther will effectually clean without ing the 
thinner covers, It will be often ful to treat both sides of the 
covers thus, as one side generally adheres while the other is subject 
to the friction. 

For cleaning slips and covers by hand, finishing should be done 
with old fine cambric handkerchiefs. These should not be 
with soap, but with common soda and hot water, plenty of the latter 
being subsequently employed to get rid of every trace of the alkali. 
But when dry these cloths must not be ‘ironed’ or smoothed in any 
way, the ‘rough-dry’ surface acting admirably for wiping delicate 
glass, 

Varnishes and Cements.—There are three very distinct purposes 
for which cements which possess the power of holding firmly to glass, 
and of resisting not merely water but other presence liquids, 
are required by the microscopist, these being (1) the attachment of 
the glass covers to the slides or cells containing the object, (2) the 
formation of thin ‘cells’ of cement only, and (3) the attachment of 
the ‘glass plate’ or ‘tube-cells’ to the slides. The two former of 
these purposes ate answered by liquid cements or varnishes, which 
may be applied without heat ; the last requires a aolid cement of 
yreater tenacity, which can only be used in the melted state. Among 
the many such cements that have been recommended ‘by different 
workers, two or three will bé selected by the worker for general 
purposes, and perhaps three or four for special purposes, and the re- 
mainder will be in practice neglected. We do not hesitate to say 

















384 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


the but moderate heat of an oven, until so much of its 
0 oil Tepe tanh ay eek spncmnti one 

resinous on cooling. If, when a drop is spread out on a glass 
allowed to become quite cold, it ix found to be so hard as not to 
i thumb-nail, and yet not so hard as to ‘chi 
‘it is in the best condition to be used for cementing. If too soft, it 
will require a little more hardening on the slide, to which it should 
‘be transferred in the liquid state, bei 
if too hard it may be in chloroform or ben- 

jum 


ae 


tended 
cell dead instead of bright, this can be 
opaque ce i brigity¢ et can by Gen pee ed 


but it may be employed to put a thin film upon the of 
mounts—howeyer cl and finished—that are to be used with homo: 
geneous lenses, It is a sure protection against the otherwise in- 
jurious action of the cedar oil, Hollis’s liquid glue may also be 
employed with confidence for this purpose. 

Sealing-wax varnish, which is made by digest powdered 
sealing-wax at a re heat in alcohol, should never be used as a 
cement ; it is serviceable only as a varnish, and resists cedar oi). 

Venice turpentine is the liquid resinous exudation of Abies larix. 
Tt must be dissolved in enough alcohol to filter readily, and after 
filtering must be placed in an evaporating dish, and by means of a 
sand-bath must be reduced by evaporation one-fourth, 

This cement is used for closing glycerin mounts, are covers 
are used, and we find it best to edge the cover with peste 
A pear hg pela ig ear Ne Ger eerie ra! one 
end of it is bent just the I of one of the sides of the cover at 
right angles to the length of the wire, ‘This end is now heated in 
spirit lamp, plunged into the cement, which adheres in fair quantity, 
and is instantly brought down upon the slide and the margin of the 











v is hung up to dry ; and are cut out from it by 
punches of two different ‘sizes, One of these rings being laid on 
i glass slide, and the cover, with the dried upon it, laid on the 
ring, it is to be held in its place by ee ip, and 
the slide. warmed so as to cause a slight ; oof the 
Gia SE eee enaic ase 
then be rendered complete by laying another glass slide on the cover 
and i Rpg ere seesracgenicges meceyrre oor i 
gent 


. Cement-cells.—Cells for mounting thin objects in any watery 
medium may be readily made with asphalte or Brunswick black 
varnish by the use of Mr. Shadbolt’s ¢ turn-table’ or one of its modi- 
fications (p, 391). ‘The glass slide being placed sales ea in 
such a manner that its two edgesshall be equidistant from the centre 
{egnide to which position is afforded by the circles traced onthe brass), 
its four corners ejuallx Projecting beyond the circular margin 
of the plate, a camel's-hair pencil dipped i ii 
right hand, so that its point comes into contact with the glass over 
whichever of the circles may be selected as the guide to the size 
of the ring. The turn-table being made to rotate by the spallation 
of the left foretinger to the milled head beneath, a ring of varnish, 
of asuitable breadth, ismade upon the glass ; and if this be set aside 
ina horizontal position, it will be found, when hard, to present: avery 
level surface, If a greater thickness be desired than a single snpls 
cation will conveniently make, a second layer may be 
laid on, It will be found convenient to make a considerable number 
of such cells at once, und to keep a stock of them ready prepared for 
use, If pares > any ing soa a oe a Saenee level for “ 
covering glass to lie fat upon it, a slight rul upon a piece 
fine pe paper laid pai flat table (the siog telet held down~ 
wards) will ee 80, " —— : 
« Ring-cells.—For mounting objects ter thickness it is 
desirable to use cells made by cementing mage oer of glass or metal 
to the glass slides, with marine glue. Glass rings of any size, dia- 
meter, thickness,and breadth aye made by cutting transverse sections 
of thick-walled tubes, the surfaces of these sections being ground 
flat and parallel. Not only may round cells (fig. 326, A, B) of yari- 
ous sizes be made by this simple method, but, by flattening the tube 
(when hot) from which they are cut, the sections may be made quad: 








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i # 3 Hall #2 i eae syadeicks 

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ul ia AE anita Hee Hi Tsuru ita 
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Huan Hy 
Hish hile ane ry] 4b 
Beret inn 0 a 
tania USM: He 
Seine HE ihe 
sna i Us he 
a ee EES 





BEcaziEe 
i tr 
i in 
Fetsis 


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& 
are 
BEE 


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s 
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attached by 0 ; if, however, it be h and the part 
it to be attacl have an irregular surface, it is desirable to form 
“bel' to this by gum thickened with starch, If, on the other 
hand, it should a desired to mount the object edgeways (as when 
the mouth of a foraminifer is to be brought into view), the side 
of the ghiest may be attached with a little gum to the’ sal of the 
cell, e complete protection thus given to the object ix the 
great recommendation of this method. But this is by no means 
its only convenience. It allows the slides not only to range in 
the ordinary cabinets, but also to be laid one aginst or over 
another, and to be packed closely in cases, or secured by elastic 
bands ; which plan is extremely convenient not merely for the 
saving of space, but also for preserving the objects from dust. Should 
any more special protection be required, a thin glass cover may be 
laid over the top of the cell, and secured there either by a rim of 
gum or by a perforated paper cover attached to the slide; and if 


It will be found a very convenient plan to prepare a large number of such slides 
at once, and this may be done in a ey Sepa ee time if the slips of card have 
jously eat to the «xact size in a bookbinder's prose The alides, when put 


been 
Loguther, should be in pairs, back to back, and every pair should have enclt 
of its ends poche! pace apelug-proan (0g. 830) wntil ry: 





— 


392 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


applied either in the. of cells or in the of ob- 
jects, it is desirable that the slide should not be exposed te 
the flame, but that it should be laid upon a surface of 


temperature. As cementing with marine glue or hardened 
a heat above Patree Plage wutecy tt aiperabe 
supplied by a Beli Gage yarn tenga 1 ed sare gram 





Fio. #3,—Apparatus for proparing ae modia, paraffin, &e. for imbedding 
ent. 


advantage of a plate of this size and thickness consists in the 
gradational temperature which its different parts afford, and in the 
slowness of its cooling when removed from fe lamp. When many 
cells are being cemented at once, it is convenient ‘to have two 
such plates that one may be cooling while the other is being heated. 

Tt is also needful to have a smaller plate, much thinner, of brass, 
having a groove cut in it into which the ordinary 3x 1 in. mounting 
ae. can easily slide, but so grooved as to leave a space between a 
ledge on each side on which the slip rests, and the main surface of 
the brass under the slip, In this way there is always a film of 





394 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


found consi Or if a 
pole pepe ne hoy ee 
SEnmigteaae 


for variety of all that ine 
" igor ar erty Sea etiieysaale 
to 
them (fg. 336). One of these 





Fro. 836.—Spring- press, 


clip, and filing the lower to such a that when it rests on its 
as cto tt abel Rete tone to the surface of the table, as 
founting Instrument--A simple mode of raduated 
| pressure eoncurrently with the heat of a lamp, be found 
very convenient in the mounting of certain classes of objects, is 
afforded by the mounting instrument devised by Mr. James Smith. 
This consists of « plate of brass turned uy ees rare fey 
size to allow the pelea ee glass slide to lie loosely in the 
formed ; this pals has a large perforation in its centre, in order to 
allow heat to directly applied to the slide from beneath ; and it 
is attached by a stout wire to a handle shown in tig, $37. Close to 
this handle is attached by a joint an upper wire, which lies 
nearly parallel to the first, but makes a downward turn just above 
the pale of the slide-plate, and is terminated by an ivory knob ; 
this wire is pressed upwards by a spring beneath it, while, on the 


=P 


Fio, 887,—Smith's mounting instrament, 


other hand, it is made to approximate the lower by « milled head 
turning on a serew, so as to bring its ivory knob to bear with greater 
or less force on the covering glass. The special use of this arranges 
ment will be pated hereafter. 

Dissecting Apparatus.—The mode of making a dissection for 
microscopic purposes must be determined by the size and character 
of the object. Generally speaking, it will be found advantageous to 
carry on the dissection tet water, with which aleohol should be 
mingled where the substance bas been long immersed in spirit, The 





396 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


a Were itt body under diate ieee erate more 
Pte anny object, the: seg jould have a nex tones 
sec for this Tarps alee be of unusual size, some of the 
glass cells already described (figs. 337-328) will usually answer very 
well. The finest dissections may often be best made ordinary 
slips of glass, care being taken to the object suffici sure 
rounded by fluid. For work of this kind no instrument is more 
generally serviceable than the erecting binocular form of stand as 
recently modified for dissecting purposes by Swift. It is an instra- 
ment which combines conveniences and supplies wants which only 
a worker at dissection could have known. It is illustrated in fig. 
338, and will be thoroughly suitable for all the work in which it 
be required, from diatom mounting to the most delicate dissections. 
‘The supports for the hands on eit side of the pa have an 6x- 
ire ely ie curve, and the instrument lends itself admirably to 
the worl 

‘The inatruments used in microscopic dissection are for the most 
part of the same kind as those which are needed in ordinary minute 
anatomical research, such as scalpels, scissors, forceps, &e. ; the tine 
instruments used in operations upon the eye, however, will oy 

be found most suitable. 


pair of delicate scissors, 

curved to one side, is ex- 

= tremely convenient for cut- 
ting tubular ; 

Fro, 889,—Spring scissor, these should have their 


points blunted, but other 
acissors should have fine points. A pair of very fine-pointed scissors 
(fig. 339), one leg of which is fixed in a light amatee and the other 
kept apart from it by a spring, so as to close by the pressure of the 


1 ‘These may be recommended as useful in a groat variety of manipulations which 
are best performed under « low ninifying power, with the conjoint use of both 
eyes. Where « high power is noeded, recourse may be advantageously had to 
Messrs. Bock’s &-inch achromatic binocular magnifier, which is constructed om the 
waane principle allowing the object to be brought very near the eyes, without 
requiring any uncomfortable convergence af their axes, 





398 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 
the itor's fingers, Tn fact, the instruments which we have 


ial, with the o needles in 
tin wory are chown nth we ars and 341, "The two-bladet 
Valentin was much 


knife contrived by Professor formerly used for 
of soft tissues ; as such 


Fo, 62—Simple microtome, ‘eke and supported; andthe 
: regulated by « mechanical 
contrivance ; such are, in particular, the stems and roots of plants, 
and the horns, hoofs, cartilages, and similarly firm structures of 
animals. Various costly ma- 
chines have been ceyoen Med 
this purpose, some 
characterised by great in- 
genuity of contrivance and 
beauty of workmanship ; but 
most of the purposes to which 
these are adapted will be 
found to be answered by a 
very simple and inexpensive 
little instrument, which may 
either be held in the han 
or (as is preferable) may be 
firmly attached by means of 
a T-shaped piece of wood 
(fig. 342) to the end of a 
Sebth be eh ee may 
be provided with a clamp for 
firm attachment to the work- 
table,as in fig. 343. ‘This in- 
strument essentially consists 
Fa, 34i,—Microtome, of an upright hollow cylinder 
of brass, with a kind of piston 
which is pushed from below upwards by a fine-threaded or ‘miero- 
meter’ screw turned by a large milled head ; at the upper end the 
cylinder terminates in a brass table, which is planed toa flat surface, 
or (which is preferable) has a piece of plate glass cemented to it, to 











400 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 





the student be but rightly directed as to pe becaetinn Gee eid 
way of em thet, end at the same time havo the baat 
concisely indicated to him, he will soon discover 
im will be the most facile and method of obtaining the 
best results, In the hands of an wore L wit 
ee eacetbonn eonteae ety tacae aN aE We there- 
fore describe one microtome which we acter an olin 
the best, and sufficiently indicate the character and peculiarities 
two or three others to enable the student, Se 
himself in consideration of his future ee as to hich et 
serve him in the he has in 
Tt will be ns well, however, to ipane that extremely vat maces 
are not the supreme purpose of microtomes. Good sections, treated 
with success from ka cur ke pais ty te first consideration. The 
tenuity of a section must Hl ee the character of a tissue. 
Nevertheless nothing is gained by yet a tissue thicker than is 
pongan fea e Cora ye ec ee 
more, we can with certain success employ the via Tor 
will admit of, and penetrate all its substance as fully as low 
power and narrow aperture, and with vastly more satisfactory 
Manifostly a tissue with injected arteries or veins must berrepeit rao thick 
to contain some of these vessels with their branches entire. 
If we require to study the hepatic cells or the renal tubules we must 
give depth enough in the sections to include these. But it will be 
fond that the hardening and embedding agents contract greatly, 
without distorting, the anatomical dune and sections muck 
thinner than w be normally ined to completely disclose 
what is sought may be often successfully made in tissues so prepared. 
Tt is none the less true that a mere race for extreme attenuation 
in sections is in every sense undesirable; and for rxtremely thin 
sections—say the gqlypth of an inch in thickness, or less—only small 
sections should be attempted. 
Here it may be advisable to state that the standard unit in 
microscopy as accepted by the Council of the Royal 
Society,! is the yylyoth of amillimétre, which is indieated by the sign 
#, being known as a micron, 


+ Journ. Roy. Microse. Soc. sar. i, vol. vii. pp. 002, 696; Nat, xxviii, yu 924. 


THE THOMA MICROTOME 40L 


The choice of microtomes, English, Continental, and American, ix 
joker nares ‘merit is characteristic sf coany sab onaice 
these, by and made by Jung, of Hei , entered 
the field carly, es ne ee 
sound, practical A as a result it has been ib! 
of and has lent to every improvement suggested by the 
advancing refinements of this beautiful art of microtomy. its 
latest form we describe and illustrate it, satisfied that it will in 
an almost perfect manner meet the general wants of the biologist’s 


This yicrotome is based upon the model of Rivet; but that has 
been immensely expanded in detail. The body of the instrument 
consists of three plates, the middle plate, M, and the side plates, S 
O, fig. 344. These are to the bottom plate by screws. 
‘supports the knife-slide, MS, which rests at three points on a planed 
polished track ; whilst on the side of the knife-slide two other 


EEE 





Fra. 344.—Jung's Thoma microtome. 


Ee slide upon the middle tg Thus in the angle in which the 
carrying the knife slides there are five points of contact on 
polished stirfaces, the block itself having weight enough to keep the 
whole steady, so that at a touch it glides to and fro with a firmness 
and precision that could scarcely be attained in any othor way. 
plate O is an inclined plane, its highest point being in the 
direction of M. The inclination of the angle is 1: 20; it supports 
the ‘aretaad OS, which rests in its pluce exactly as does the 
holder, MS. 


knife- 
This also bears the scale Th, which, by means of a vernier 
on the object-holder, enables the thickness of the section to be read 


he bottom plate is at once # base nnd a receiver for the drip 
ping spirit, oil, ce. 
Kor fastening the knife a thumb-serew, C, fig. 344, serves 3 but in 
the instrument desi, by the Zoological Station, Naples, this is 
DD 





402 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


ro} a single head-screw, E, fig. ia erhiarlitis 
Tleranl onto posers ine ira peiscereotoat 
eee ete Gales fecearo wtctral Hola led and tapped into 
wi 

‘The knives, of ne he form A, 344, rad screwed directly 
to the knife-slide, and are capa ‘of the ujonten for he 
Fh pe AT ak eed EU SA dd 


The knife, however, is also made upon another model, E, fig. 345 ; it 
then has a special holder a, and is secured in conical apertures by the 
xerews 6,1, and firmly held ; and as 6 or b! corn farther, the 
edge era be adjusted towards « horizontal 

leep objects requiring considerable th to cut from, there 
are plates provided for elevating the knives and the knife-holders. 




































































Fro, 445.—The Thoma microtome with special knife. 


‘The exigencies of section-cutting have given rise to.a great variety 
of section-holders in this instrument. The simplest is seen in OS, 
fig. 344, which is a pair of jaws clamped by screws and fixed upon 
the pivot St by the milled head a, At.» is the vernier, which indi- 
cates the position on the mm. scale, ‘Mh, and ¢ is an agate highly 
polished upon which the micrometer screw m works to drive forwant 
the object-carrier, OS. 

The Zoological Station at Naples employs « holder specially de- 
signed for use with paraffin ; the object is soldered with parafin on 
to the cylinder, by sfig. 345. "This. may be shifted vertically and 
horizontally by' means of the small screw «, and it is fastened by 
means of the milled head, m. By the spring » it may be 
over 90°, and as great an inclination can be taken in a plane perpen- 
dicular to this by the supporting metal frames by means of the 








ae 


THE THOMA MICROTOME 403 
aqui poeta ha casita ination. af sha-dhjach.th tha 
Pitaced bared ysmatel, ig meee 


ly t 
346 presents the same object-holder, but instead of the 
inte a simple pair of jaws with screw m to seoure objects of 


bo 





16.—Object-holiler with jaws. 


every variety. A cylinder-holder as in fig. 349 can be placed in 
these, from which the benefits of the Neapolitan holder can be 
eet But fig. 346 shows a still greater improvement which can be 
rg both object-holders, ierk « peemacicnioc displacement by 
of @ cog and spring governing the height of the mass from 
which, the sections are to be cut. 


The olevator in this case is supported on one side by the pri 





ism P, 


and on the other by the rod C; these are joined by the bridge }, 





© Fis. 17. —Odject-holder movable about two horicontal axes at right angles 
to each other. 
to which a bar is fastened, into which a spring catches, which 
: pring 
is moved by the lever V, allowing a perpendicular displacement of the 
wbjectof 12mm. At O is the millimétre scale on which the perpen- 
dicular displacement can be read off by means of the index x. 


po? 








be 


7 


404 PREPARATION, MOUNTING, AND COLLECTION OF ORFECTS 


An object-holder movable about two horizontal axes situated: 
perpendicularly to each other is seen in fig. 347. These positions 
are fixed by the milled heads !,6 ; ¢ shows the jaws for the 
object, into which, however, cylinders like fig. 349 may be intro- 
duced, This object-holder has a perpendicular Ward pepe con 
trolled by a screw, The party K, which eupporta te ief axis of the 
jaws is fitted on to the lar prism Sf, the lower part of which is 
furnished with hinges ; on the hinge the screw V moves, which at its 
upper end lies close to K, and is sustained in this position by the 
steel plateg, so that K is carried up and down with it, and this move- 
a Gah t oats 

. 318 presents an object-holder intended to moan br i) 
jae objects which are wedged or reread a fixed 
axis, but may be applied to other purposes, 





Fio. 848 —Object-holer for analysis by diversified section. 


B is a prism-shaped, semiciroularly bent bar, moving in the slot 
FF'; at 6 and 6! the jaws occupy the position common to those of 
the ordinary form, 

On the circumference of B a spiral is eut, which becomes slightly 

visible at g ; into this spiral a screw passes at H, which is turned by 
the milled head 8, which can alter the position of the are to the 
horizontal to the extent of 1 mm; and the amount of the change of 
n can be read off on the graduated circle K, 
a fixed position the middle of this section-holder is the plane 
of action of the knife. If an object be fixed in the jaws so that the 
fixed axis of it lies in this plane, it will only be required that 
the serew S be brought into action to obtain wedge-shaped sections 
of whatever thickness is req i, which will all be made in this 
axis, 

‘The sot of cylinders which may be used with these and other 
jaws is esented in fig. 349: by is the cylinder, G the compressing 
screw for it, the mass W being held in the jaws. 

The object alide with its eernier may be slidden up the in- 
cline ; but itis much more accurate to control its movement with the 


















THE THOMA MICROTOME. 405 


r, ‘The point of it in tig. 345, ¢, works on the polished 
of an agate cone, The thread in which the screw works is 
in its by the milled head W in Sch. It may stretch 

up as far as O, refastened by W. 
‘The serew m is so cut that a single rotation moves the slide on 
the ff mm., which in the inclination of the plane of 1 : 20 gives 


St. 





Fira, He. —Cylinder lor use with jawe 


an elevation of the objectofy)f, mm. The barrel or drum, K, 

situated on. the axis of the screw, is divided into fifteen parts ; con 

ame theinterval of each division corresponds to an elevation of 
min, 


is also an action by means of a spring which gives th 
car as well as the eye cognisance of the amount of pms which 
hus taken place, which greatly relieves the eye. This, however, can 
he brought into action or not at the option of the operator. 


[promt 











Fis, 824. —Freeting apparatus for the Then microtome. 


‘Besides these object-holders a freezing apparatus can be added 
which is simply placed on the object-slide as show ig. 350, 

The | is effected by ether-spray. A specially favourable 
effect is obtained if the cylinder g is mica and not glass. A layer of 
water freezes in from thirty to thirty-five seconds. 

Tn fig. 351 is shown a similar arrangement as an independent 








406 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


instrument. .A is the plate on which the preparation is laid, 
mica cylinder, and B the under-setting of it in which the ether 
for the production of the spray are fixed. No. 1 tube is 
the bellows; No. 2 carries air to the ether bottle ; No. 3 is for 
spray point of the ether bottle itself ; and No. 4 is the overflow 
excess of ether, 

‘The glass plate G serves as the knife-rest ; b is divided in order 
to determine the thickness of the sections (1 division = mum.) ; C 
is the micrometer-serew which raises the object ; Ris the screw 
which fixes the clamp toa table; D is the knife commonly used ; 
and E « stilet for clearing the spray points without the 
openings. 
: Fig. 350 is the same instrament capable of being used with the 
microtome instead of separately. 


ai 





Fin. 251. —Independest freezing apparatan 


An arrangement of this machine for cutting large objects has 
also been devised which is illustrated in fig. 352. 

The knife is to be placed considerably higher in front than 
behind, in order to lessen the pressure on the objects. In order to 
satisfy all demands, the knife-rest is adjustable. 

The knife is so arranged that the whole length of blade can be 
used, and then the screw c is fairly tightly screwed down. As strong 
knives, even of a length of 36 cm., easily give, a knife-support has 
been constructed ; this is fastened by the serew ec’ to the carrier. 
The support is arranged parallel with the back of the knife M; if 
the extremity » be slightly pressed backwards, so that it touches the: 
knife, it is then fixed in this position by the screw o (scarcely evident 
in the illustration). ' 

This done, the spirit-vessel Sp can be arranged in a position 
which will not interfere with the free movement of the k In 














THE ROCKING MICROTOME 409 
h the boss. The Lottom of the screw rests on a pin fixed in the 
Te will be seen that the effect of turning the screw is to raise or 


Fro. 85% —Tho Cazibridge rocking microtome, 








ie desu 


detinite 
a 
postion 


is 
s? 





inch. The value of the teeth on 
1 tooth of the “ees in, = "000625 mm. 
Qtech 4 = in. 
ty ” ” = 
Wo» ” ” = 
The movement of the lever which carries the imbedded object is 
effected by a string attached to one end of the lever. This string 
eae and is fastened to the arm ing the pawl. 
Attached to the other end of the lever isa spring pulling downwards. 
When the arm is moved forward the feed takes place, the string is 
pulled, the imbedded object is raised past the razor, and the spring 
is stretched. When the arm is allowed to move back, the spring 
draws the imbedded object across the edge of the razor, and the see- 
tion is cut, The string is attached to the lever by a screw which 
allows the position of the imbedded object to be adjusted, so that at 
the end of the forward stroke it is only just past the edge of the 
razor. ‘This is an important adjustment, as it causes the razor to com- 
mence the cut when the object is travelling slowly, and produces the 
most favourable conditions for the sections to pikes to each . 
The following are perhaps the most prominent advantages of this 











ily é 
is placed Mision plate F, and the spray which plays aaa 
surface of the plate F set working by the hand-pamp, M.; in a’short 
time the tissue will be frozen quite through, and if a number of sec- 
tions are required an. ional stroke or two of the pump will keep 
in proper condition for cutting. The sections are easily cut, 
48 in other microtomes of this class, by alternate movements of the 
serew Z and stroke of the razor. 

‘The instrument may also be used for cutting tissue imbedded in 
paraffin or other mass, the object tobe cut being secured in position, 
either by being gently heated at its under surface and pressed on the 
plate F, to which it firmly adheres on cooling, or Vike simple clamp- 
aoe Aarne which can be substituted for the freezing-chamber. 
When used in this way large numbers of sections may be cut in series 
by attaching to the razor a light support to receive the sections as 
they are cut. 

Another most serviceable and admirable, because inexpensive and 
efficient, microtome, especially for freezing purposes, was devised by 
Mr. Cathcart ; and it is now presented in a simplified and improved 
condition. The instrument is illustrated in fig. 355, 

In this form the clamping arrangements are much more perfect 
than in the old form ; the principal screw and its milled head are 
larger and more convenient ; the freezing-plate is circular, and is 
provided with an arrangement for preventing the ether with which 
the freezing is effected from reaching the upper side of the plate ; and 
the instrament is now so modified that it can be used for ordinary 
imbedding as well as freezing. 

The increased size of the screw gives a more steady movement 
than was possessed by the older mad smaller microtome, while the 
greater circumference of the serew-head enables an operator to im- 


ETHER FREEZING MICROTOME 413. 


part a finer movement to the screw. The relation between(the pitel 
of the screw and the circumference of its head is such that if the 





Fro, 855.—Catheart’s freezing microtome, 


edge be moved forward a quarter of an inch, an object will be raiset 
one-thousandth of an inch ; and if it be moved an eighth of an inch, 
the object will be raised a two-thousundth of an inch. 


In the Ss en Bie the 
plate was supported on two pillars, in 
order that as little heat de possible 
might be conveyed to the freezing- 

from the body of the instrument. 
the new deer the size af th 
three supporting pillars and screws ix 
so much reduced that the conducting 
surface is not greater than in the old 
microtome. The arrangement for cut- 
ing imbedded sections consists of « 
tube which fits the principal well of th 
microtome, 











Pr 
Holder for Cat 


Yn microtome. 


and within which fits a hinged part similar to an ordinary 
Vice. With the instrument are provided the means of preparing 


paraffin blocks for imbedding sections. 


When it is intended to use the microtome for imbedding, the 
ether spray, spray-lellows, and ether-bottle should be removed, and 








= 


4I4 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 
freozing-tube, en ried far ‘means 
pope eycta icc = Sees Be 
rae at oa Teen 


"le Gata ws 
rhegngs ae Seencne etre 
repeats? 15 
pushed into their socket. Titanic t me 
‘viously removed by soaking for a a coir A 
Tegina to froese 7 ster his work more gently. Raise the tissue 
Stag te i in, 0c by ling 


Imbedding Processes.—The of soft organic subst 
for section: Sat “bedding may bo made in ‘two modes, 
choice between which will depend upon the consistency of the 
stance. If (1) it be compact, like a of liver or kidney, it 

by the which will afford 
axa whole the requisite su) 


ES 


a 


i 
vile 


ae 
F 
i 


E 
F 
a 
Fee? 


Fl 


set 


mass, 
pport. But if (2) it be partly 
like a pi > of Jung, by interstitial cavities, it must be 

the im! substance, so that every part may hed fs 

‘The former is simple imbedding ; and it may be ily effected 
hy immersing the object to be cut in some such substance as whatee 
wax, which on becoming cold will acquire a coaeicener ney ither too 
brittle nor too soft, which will permit. nitot thin slices bein; Bat 
in the second class of cases, where it is necessary to fest 
cavities and interstices with the imbedding material, so that the 
most delicate organ may retain its tissues, and even its separate cells 
in xitu in each section, it is much more complex. 

Tt may be effected by a similar process of infiltration as is 
employed in simple eer only made more complete by the 
previous preparation of the tissue, employing materials in. pate to 
previously soak it which are solvent the imbedding material, 
and which will therefore secure more thorough infiltration, Or 
the sme thing may be accomplished by a process of evaporation. 
A substance may be used which in a fluid taborin is ble of pene- 
trating the most delicate cavities of a tissue, ars check the evapo- 
ration of the solvent will leave the imbedded object with « consistency 
which will admit of cutting. 

For simple imbedding the use of carrot or pith will suffice ; 
using the latter, when the cylinder of pith ras been cut Toariia 
dinally, and a cavity has to be made to receive the object, the aay 
should be made by pressure ; a blunt ivory point will suffice to effect 
this. If the cells of pith be cut out, we lose the firmness of enclosure 
that is always the result of having obtained the cavity by pressure, 











: is to take a common flat medicine 

asin fig. 357, fitted with a cork which two tubes pass, or, 
small, one tube may be fastened into a hole 

‘One of these tubes, A, is with hot and 

water ; the other, B, is a for the water entering 
A, and raising or lowering its temperature as. 





; upon the thin cover for mounting, it is very 
aaa eines aks oe easy abs sections 
panera hg Raper e imbedding mass that may be clinging 
aged Loom toit, This may be done by sro of turpen- 
parafiin, tine, creosote, xylol, or oil of cloves, But in 
simple imbecding, where the interpenctration of 
the cavities of the object is not the special aim, a still more efficient 
method is to prepare the object before imbedding it by covering it 
with a film of some substance which prevents the immediate contact 
of the imbedding mass with the object, and which can be even more 
easily removed than the paraffin. This may be done with collodion, 
into which the prepared tissue is plunged for a short time and taken 
out andallowed toevaporate. The oil of cloves used for clearing the 
section will dissolve it, and the cast of wax will fall away. 
bedding Masses.—These may be procured ready prepared for 
two or three temperatures, made up according to the formule of 
some of the most experienced biologists. The composition of the 
imbedding mass is of large importance. The temperature of the 
laboratory must determine the melting-point of paraffin ; hy 








where it should remain ten or twelve 


fons ey de nl benefited by areey pelea Ea, 


A much thicker solutic lloidin must 

‘Take out the organ or tissue from the thin solution, and sutfer the 
celloidin to evaporate until a film is formed. This is done 
on a piece of leather, Surround it now with the loidin, and 
wait until again a film has formed, and then the whole is thrown 
into strong alcohol, where it may remain until it is desired to eut 
sections, 


Sections are best cut with the razor moistened with alcohol, and 
snap ee eae into the same fluid. 
mount, it is not needful to remove the celloidin if we employ 
glycerin, glycerin jelly, or Farrant’s medium (9.v.) ; but if we desire 
to mount in balsam the section should be with 95 per 
cent, of alcohol, and cleared with oil of origanum or vil of clove. 
Tl ‘ion or ~—From 


be fresh, or have been hardened by some of the processes to 
after described, must be thoroughly penetrated by a thick solution of 
gum. If the substance to be cut has been immersed in alcohol, this 
must be completely removed in the first instance by im 
water for from six to twenty-four hours, according to the size of the 
mass ; for the gum will not penetrate any part which is still 
alcoholised. The substance should be then immersed in the gum- 
solution for from twelve to twenty-four hours before it is frozen, 
in order that every part may be permeated by the gum, and no water 
be left to form crystals of ice. 

With the ether-spray microtome, which is simpler and easier 
work than the ice-freezing instrument, the freezing is uded by 
the rapid evaporation of the liquid injected into the fi 
‘The substance to be cut is to be introduced into the well, as soon 
as the gum begins to harden at its periphery, and should be held in 
place until fixed by the advancing congelation. In cutting the 
sections no ich § of the knife is » as it is kept suf- 
ficiently wetted by the thawing gum. The sections should be 
in methylated spirit diluted with twice its volume of water ; and this 
soon not only dissolves out the gum, but removes any air-bubbles the 
section may contain, If thesection is to be at once mounted (which 
should always be done if it be very delicate and liable to be Foner 
by manipulation), it should be placed on the slide before it has thawed 


e 


= 





420 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


Es 
f 


laneous shells), which, Te eee 

make it i fexrgbe eters livide them in this mode ; and 
it is much the quicker operation to slit them with a dise of soft iron 
(resembling that used by the decicary) otttcaed at Eaten dia- 
mond-dust, which dise may be driven in an ordinary 


f 


i 

H 
ti 
EEE 


& 
& 
: 
j 
E 
; 
i 
E 
z 


“F 
i 
PEE 
gt 
Ee 


. There are certain substances, especially calcareous fossils 
of wood, bone, and teeth, in which the great 
the ce of these preliminary operat 
extreme frinbility ; the vibration produced by the pons of the 
pee ati by eas tae eae icient to 
disintegrate even a thick mass, so that it falls to pieces under the 
hand ; such specimens, therefore, it is requisite to with great 
caution, dividing them by the smooth action of the wheel, and then 
rubbing them down upon nothing rougher than a very fine ‘grit,’ or 
on the ‘corundum files’ now sold in the tool-shops, which are made 
by imbedding corundum of various d of fineness in a hard, re- 
sinous substance. Where (as often happens) such specimens are 
sufficiently porous to admit of the penetration of Canada balsam, it 
will be desirable, after souking them in turpentine for a while, to 
lay some liquid balsam upon the parts through which the section is 
to pass, and then to place the specimen before the fire or in an oven. 


ly be. aly those. wh and have 
Sees cane tomraeel tes eee eee 
F Journ. Quekett Microse. Club, vol. vi 1860, 88, 


POLISHING GROUND SECTIONS 421 


e time, so as first to cause the balsam to run in, and 
en it ; by this means the specimen will be rendered 
& for the processes it has afterwards to undergo. It 
ntly happens that the small size, awkward shape, or 
Iness the body occasions a difficulty in holding it 
ting or grinding ; in such a case it is much better to 
be glass in the first instance by any side that happens 
and pene rub it down by means of the ‘hold’ of the 
until rjectii ion been brought to a 
been prepared Sa area attachment to the glass. 
od which it is generally most convenient to pursue 
to small bodies ; and there are many which can scarcely 
any other way than by attaching a number of them to 
once in such a manner as to make them mutually sup- 


Bee | 


+ in which the operation is then to be proceeded with, 
a whether the section is to be ultimately set up in Canada 
i; to be mounted ‘dry,’ or in fluid. In the former case 
; is the plan to be pursued :—The flattened surface is to 
yy rubbing it with water on a ‘Water-of-Ayr’ stone, or 
“Turkey ’ stone, or onan ‘Arkansas’ stone ; the first of 
the best for all ordinary purposes, but the two latter, 
harder, may be employed for substances which resist it.? 
as been sufficiently accomplished, the section is to be 
b hard Canada balsam to a slip of thick, well-annealed 
8 the success of the final result will often depend upon 
ness of its adhesion to this, the means of most effectually 
t adhesion will now be described in detail. The slide 
placed on the cover of the water-bath, and the previously 
lsam having been softened by the immersion of the jar 
:in the bath itself, a sufficient quantity of this should 
e slide to form, when spread out by liquefaction, a thick 
hat larger than the surface of the object to be attached. 
ould then be allowed to cool in order that the hardness 
m should be tested. If too soft, as indicated by its 
aaking horizontal and vertical sections of Foraminifera, as it would 
o slice them through, they must be laid close together in a bed of 
Ie balsam on a slip of glass, in such positions that when rubbed down 
tion shall traverse them in the desired directions; and one flat surface 
us obtained for each, this must be turned downwards, and the other 
ty. The following ingenious plan was suggested by Dr. Wallich (Ann. 
‘uly 1861, p. 58) for turning a number of minute objects together, and 
che tedionsness and difficulty of turning each one separately: ‘The 
semented with Canada balsam, in the first instance, to a thin film of 
then attached to a glass slide by the same means; when they have 
‘wn as far as may be desired, the slide is gradually heated just suf- 
of the detachment of the mica-film and the specimens it carries; and 
th a thin layer of hardened balsam having been prepared, the mica- 
ted to it with the ground surface downwards. When its adhesion is 


be proceeded with; and ee the mics-ilm will yield to the 
lificulty, the specimens, now reversed in position, may be 
tneas of the polished surface is a matter of the first importance, that 
temselves should be tested from time to time; and whenever they are 
ven rubbed down on any one part more than on another, they should 
‘a paving-stone with fine sand, or on the lead-plate with emery. 








hard, will be shown by its: it should be re-melted 
ee ee ee and Hesllepiad rr 
before. When found to right. section 
should be Iaid upon its surface with the polished side = 
‘the slip of glass is next to be ed until the balsam is 
nape eee ee to avoid the formation of bubbles ; 
and the section is then to © gently ‘upon the efied 

first applied rather on one ‘than 


sam upon the glass, and then to section upon it as before, 
‘When the Seaton bas: bon ‘and the 

attached part thoroughly saturated (i it be ) with hard 

Canada bbls, it may be readily reduced in. thickness, either by 

grinding or filing, as hgligh barat el ses 4 8 

taking off the chief part of it at once by the slitting wheel. 

ie 


soon, however, as it oie ie thinness of a piece of 
card, it should be rubbed down with water on of pig 


with such equality that the thickness of section fas 
nearly as can be discerned) over its entire 

ns it begins to be translucent, it should be placed under the micro- 
scope (particular regard being had to the method of illumination 
so as not to flood the object with li Pieler 22s 
inequality ; and then when it is again Inid upon the stone, 
inequality may be brought down by making special pressure with 
the fo upon the part of the slide above it. When the 
thinness of the section is such as to cause the water to 
around it between the glass and the stone, an excess of - 
ness on either side may often be detected by noticing the smaller 
distance to which the liquid extends. In proportion as the sub- 
stance attached to the glass is ground a] the 
balsam which may have exuded around it will be brought into 
contact with the stone ; and this should be removed with a knife, 
care being taken, however, that a margin be still left round the edge 
of tho section. As the section approaches the degree of thinness 
which is most suitable for the display of its organisation, great care 
must be taken that the grinding process be not carried too far ; and 
frequent recourse should be to the microscope, which it is 
convenient to have always at hand when work of this kind is being 
carried on. There are many substances whose intimate structure 
can only be displayed in its highest perfection, when a very little 





| 


424 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


order to bring inte view a stratum which the Canada balsam shall 
not have penetrated. As none but substances possessing considerable 
e88, such as bones and teeth, can be treated in this manner, 

as these are the substances which are most quickly reduced | 
a coarse file, and are least liable to be injured by its action, it 
be generally found possible to reduce the sections nearly to the 


3 


a 


may be rubbed down to the desired thinness ; but even the 
careful working on the finest-grained stone will leave i 
covered with scratches, which not only detract from its appearance, 
but prevent the details of its internal structure from 
made out as they can be in a polished section. This 
spate by rubbing the section with putty-powder 
water upon a leather strap, made by coverin, 
fannel or soft Ieetber Ceneatb it: tia operation est be performed 
flannel, or soft rv beneath it : o} must 
on both sides of the section, until all the marks of the scratches left 
by the stone shall have been rubbed out, when the specimen will be 
fit for mounting ‘dry ’ after having been carefully cleansed from any 
ing parti putty-powder. 

Greater facility in the grinding of hard sections, as well as supe- 
riority of result, is attainable by PAIS means. 

A cutting machine will greatly facilitate the eee 
rock slices. The thickness of each slice must be mainly 


| 


at 
Hn 


; 


be conveniently cut, so as to save labour in grinding down afterwards. 
Perhaps the thickness of a shilling may be taken as a fair average. 





Fro. 858.—Hand machine for cutting hard sections. 


‘This thickness may be still further reduced by cutting and polishing 
a face of the specimen, cementing that on glass, and then bras, rd 
close as pave to the cemented surface. The thin slice thus 

on the glass can then be ground down with comparative ease. 





pare 


es 
F 


their internal cavities (a 


found useful in the study of Moraminifera) ; or for getting rid 
of thecn entirely, 8008 to into complete pee ‘internal cast” 
which may have been formed by the silicification of igi soft, 
contents. It has been in this mode, even more than by 

of thin sections, that the structure of Bosodm canadense 

piceiiarat by Erctence: Davace el ee aee 
ese purposes, strong acid should applied (u) dissecting 


ternal cast ' may be altoge' away. 

Bush suggests nitric acid as the best of all agents for decalcifica- 
tion, insomuch as it does not cause ‘swelling up,’ nor inj 
attack the tissue elements. 

‘One volume of chemically pure nitric acid of specific gravity 1-25. 
diluted with ten volumes of water may be employed for and 
tough bones ; but it may be diluted to 1 per cent. for 

i method given is that fresh bones should be ‘on a 95 
cent, solution of alechol for three days ; they must then be in 








a = ' 
428 PREPARATION, MOUNTING, AND COLLECTION OF on/ECTS 


manner into chemical combination with the: edn eben 
Palladior, “ks tiene ep peotaces site Bat dha Mahe 
‘not lend themselves vo mca taining igh hy i of 


Alcohol.—This should be used bering 
—_ Hi 
te alohol ; but Be 


of spirit should be em) in ii and 
we A eatial te bersad ena reece bos 

Picric acid is used for the same purposes as chromic acid ; its 
arden power. a tint wo greet bat 42 shes ates 
45 much, its action is more rapid, and it may 
used where ‘decalcification’ is necessary. As i 
nny of Tigi al aa loerhedeeniy ite 
quantity should be large in proportion 
stance to be acted on, Picric acid is used, in combination with 
carmine or anilin blue, as a staining material. 

Ovmic Acid.—This agent is one of value to the micro- 
scopist whose studies lie among the form: 
vegetable life ; ns ita, applleation 4 immediately kills them, without 
producing any retraction or shrinking of their parte and ‘nob only 
preserves their tissues, but brings out differences in those 
might otherwise escape observation, pep dedehmee ties 2 
in sealed tubes, and is most conveniently kept as a 1 per cont. 
solution in distilled water. The solution should be preserved in 
well-stoppered bottles secluded from the light ; and should be 
with great caution, as it gives forth » pungent vapour whic Ss 
irritating to the eyes and nostrils. ded by 
Pelletan,! M. Certes,? and M. Raphael ‘Blanchard for fixing and 
preserving piace farsoria ise Rotifera), Desmidiew, Dia- 
tomace, Bacteria, Vi y Dr. Vignal for Noctiluea ; 

Mr. T. Jeflrey Parker ® es Ruonoeee wok onert eal 
‘rustacea ; and it has been successfully used also in the preparation | 
of insect structures. To the histologist its special value lies in its 
blackening of fatty sos sae pases meat anne ce ahi 
fibres. And the em logist it value 
firmness and distinctness te the delicate vekinrea vith Rian Ponce 
to deal. Various degrees of dilution of Hore cent. solution will 
be needed for these different purposes. ‘ker further states 
(loc, cit.) that he has found this patiee ae serviceable in the 
inert of delicate vegetable structures. ‘The acid seems to 

ken up by each granule of the protoplasin, and these to be 


4 Journ. of Roy. Microsc. Soc. vol. i. 1878, p. 
rel 1379, p. 8815 and Comptor Bendis, 1870, p. 488, 


i ve 
Physiologie, tome xiv. 18T8, p. 680. 
Sgeuirmc of Boy. Moroes os, 2a i 1870, pe gh 


he 
£ 





uy Tea THOS HET 
es Led tees tte 
te i Hu : a HE Tue 
He ult i la painted 
q = is: gage qesqiih 
ue alist shai HP th| 
tlie: i Hee He Hiteeiee 
a CC ane a ce 

i i 


oe 


a ee Tmothods of hardening mucons glands 
tried, the mucous granules are more or less altered, 





which I have 
being either 


Bichromate of potass, ii 2 Ltda # lution, be 
in a cen! ‘80! 

used where “nt pelo ren With 

the addition of 1 per cent. of s1 of soda, it Miller's 


Processes.—Much and nied attention has been 
sSipees ice ete years fa tbe nike pe agers ich, either by simply 
lyeing or by chemically rar Bes organic substances in different 
seh phe h Saat alle if tiate the different parts of organs 
or tissues of complex structure, and to render more distinct such 
delicate features in preparations mounted in transparent media ax 
might otherwise eseape notice. One of the chief ends of staining 
animal tissues is to obtain a clear stain of the nuclear parts—tho 
nuclei and their surrounding cell-protoplasin—as distinct from the 
non-nicleated parts of the same tissue. The agents which 
dye the tissues are for the most part colouring matters 
or animal origin; those which act upon them i are 
mineral substances. The staining Wiser may be used either 
before or after section-cutting, according to circumstances. Where 
the substance is in mass, and is not readily penetrable by the 
staining fluid (which is especially liable to be the case where it has 
been hardened in chromic acid), it is generally better to stain the 
sections after cutting, if they hold sufficiently well together to bear 
being transferred from one fluid to another ; and if the substance 
is to be imbedded in gum, and cut with the freezing microtome, it 
is generally preferable to stain the sections after they have been 
eut, as the processes necessary for the removal of the gum would be 
likely also to remove the dye. But where the substance to be cut 
has to be penetrated by wax or parafiin, it is better that tho stain- 
ing should be effected in the first instance. Asa general rule, it is 
better that where the substance is to be stained en masse the 





oT histrtoozen! 
SN ere 
wiped ides 





432 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 





Fro. 800, i pie: \ife the turpen- 

tine in which section is resting 

prior to mounting pis gently disturbed, in a good-sized vessel or saucer, 
until the section desired is in its position onthe cover. Now 


lny the cover, section upwards, on blottin, , to take off 
erp sous turpentine from the free se of the cover, and then 

e edge of slip at an angle, more or less acute, with the 
section towards the leben al but never suffering the former 
to touch the lattter ; when this has removed the superfluous turpen- 
tine from the section, lay the cover section upwards, on a glass slij 
put on (say) the benzole balsam until it stands in an evenly diffased 
mound covering the section, and lay it aside absolutely protected 
from dust for twenty-four hours in order that the benzole may 


‘ow take it out, place upon the centre of the section one small 
drop of fresh benzole , and turn the cover over on te a warm 
slip, being careful to have guides to the position on the slip on which 
it should fixed ; and in an hour or so we may clean off superfluous 
balsam and finish the slide. 

To those who mount much this will prove the quicker plan, as, 
for fine results, it is undoubtedly the better. 

It would be impossible in this treatise even to attempt to enu~ 
merate the principal stains now employed in the botanical and 
zoological laboratories where hii is pursued. 

It will be the utmost we can find space for if we indicate those 
which we, from experience, have found most useful.' 

Hematovylin.—We believe this to be, in spite of some of its 
defects, one of the best, if not on the whole the best, of all stains. 
It is well known that it is the active principle in the extract of log- 
wood. It is not eae! or easily extracted ; but it may be obtained 
in the market Li . 

An aqueous solution of it may be made in either of the following 
ways, Vizi— 

1 For fuller information see the Microtomist's Vade Meoum, B. Leo: Cole's 
Studies; Practical Histology, Fearnley; Botanical Micro-chemistry, Povlvon. 


= 



















LOGWOOD STAINING 433 


Dissolve -35 grin. hematoxylin in 10 grms. water. Dissolve 
alum in 30 grms. water. To the hematoxylin solution add 
of the solution of alum. It makes a beautiful violet 
stains nuclei a deep blue. 
60 gris. of dried extract of hematoxylin, 180 grms. of 
alum, and work them thoroughly together with a pestle 
, adding by degrees 300 c.c. of distilled water. Mix the 
lly and then filter, after which add 20 c.c of absolute 
Xt should be kept some time, well stoppered, and in a coo 


ing 
fie solution may be prepared by making the three fol- 
saturated solutions, viz. (1) calcic chloride in 70 per cent. 
(2) powdered alum in the same, and (3) hematoxylin in 
alcohol. Mix one part of the calcic chloride solution with 
of the alum solution, and add the hematoxylin solution 
drop until a deep purple colour is attained. The colour 
richer by time. 
stain with either of these solutions take 2 few minims of the 
and in a dram of distilled water, then filter into a 
bed above. Be provided with a 5 per cent. 
of sodium bicarbonate, and if the tissue has been hardened 
ehromium or acid medium it must be placed in the bicarbonate 
being put in the stain. In fact, tissues or sections must 
be c/rared of all trace of acid before being put in the stain ; 
this is accomplished they must be washed in distilled water at 
to 40° C. Place the sections now in the hollow of the 
containing the filtered solution of hematoxylin for a period 
may vary from five minutes to many hours ; in the latter case 
1 containing the stain should be kept in 2 moist chamber. 
» what has been already stated it will be understood that, 
staining, all sections to be mounted in balsam must be dehy- 
or deprived of all water, which may le readily effected by 
minutes in methylated spirit ; they must then he eletred in cil 
until the section sinks in the oil, when it is transferred to 
tine and mounted. 
a logwood staining has been carried to excess it may be greatly 
peed, und indeed brought to a desirable intensity, by heing placed 
ma few seconds to a few minutes in the following solution, viz. 








1 per vent. hydrochloric acid in distilled water. 1 part 
Absolute alcohol =... 2 parts 


This acts in the same way with tissues over-stained with carmine. 
Wgwoul stains vegetable sections with extreme delicacy and great 





inv ‘A. Hill, of Downing College, Cambridge, has 
mtifol results an original method for apply ig 
gylin stain to nerve-cells, andto him the Editor is indebted for these 
herwise unpublished details. As ordinarily used it is considered 
be one of the virtues of Weigert’s well-known staining method 
at the medullated nerve-fibres are stained a deep violet, while the 
ty matter through which they run merely -takes on a brownish 
FF 












434 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


RHE SRY pe ee lace in a shallow dish carmine, 
potash, alum, an‘ water, u 
the water being restored to its from time to time as it 
evaporates. Both carmine and alum should be in excess, ie. in 
larger quantity than the water will dissolve. When cold the sola~ 
tion is decanted and filtered. (5) The tissue ix then into. 
sections which are for twenty-four hours in a 
acetate of copper saturated ; for convenience a saturated, 
is kept and mixed with an equal volume of distilled 
use, (6) From the acetate of copper the sections are 
hematoxylin mixture for eight as ae 
at a temperature of 40° C. vive. At the end of thi 
sections are ae black and tea with ‘ipitate ote 
toxylin. (7)'The sections are then ised to exactly 
aeons of ferricyanide of ium. It is well to 
have a basin of water at hand into which the sections are placed 
from time to time to ascertain the of thedecolorisution, If 
the sections are imbedded in celloidin it may always be safely 
assumed that the matrix of the tissue and the imbedding celloidin 
will be decolourised at the same time, 

‘This method gives extremely good results when applied to the 
cerebellum or to groups of large nerve-cells such as constitute the 
nucleus of the third and other motor cranial nerves ; es ra 
graph of a section of the cerebellum of a lamb by Dr, Hill 
iy given at fig. 4 of the frontispiece, It eaten epee xi7 
diame. with a I-inch apochromatic objective of N.A, 3, and sufficiently 
illustrates the value of Dr. Hill's method, 


ips 
Bue 


; 
if 


Weigert’s hwmatoxylin solution :— 


Crystallised banat lin . . 1 granune. 
Dissolved in absolute alcohol = ria 10 c.c. 
Add distilled water pe ee ge 90 cc, 
Lot the mixture come to the boil. 
Weigert’e deoolourising mixture :— 
Ferricynnide of potassium =, =, 2 grammes. 
Borax. .  . + ee) S erammes. 
Warr 6 6 6 + + 6 20000, 








436 PREPARATION, MOUNTING, AND COLLECTION OF OTJECTS 


Mr. A, Cole has effected some y beautiful vegetable 
stains with another gree . 
i, Take 10 borax and dissolve in 1 ox. of distilled 
add 4 of and 4 drachms of alcohol. 
ii, Take 10, carmine and dissolve in 20 minims of 
ammon, fort. and 30 minims of distilled water ina 
with gentle heat. Let it cool, then thoroughly mix i. and ii. ; 





and keep in a well: bottle, 
Next make a saturat Coenen Oe te 
Bleach the sections in it } solution. Wash or 


Picro-cerminate of ammonia, known as picro-carmine, is a very 
shearer re y Shiel is Spee Se aie 
somewhat difficult to is purchased 
bp ee ds Martindale, New Cavendish Street). Use a 2 
cent. filtered solution and let the section remain in from half an 
Pour weve a mare oar wash rapi cate ah mount in 
arrants’ solu lycerin, or balsam. iis alone, | 
rap eared the nuclei fixing upon the carrier waists 
aie ee a coat aed. palin ty a ee Tf the sections 
lee tasnerens eit spirit, they may be kept without loss of colour 





be afterwards subjected to other Té placed in 
water the picric acid stain is removed, while the carmine is left. 
Magenta ins nearly the same s/ective staining property as car: 


mine, and is useful in the examination of specimens for which 
action and sharp definition are required. But, like other amilin 
dyes, it is liable to fade, and should, therefore, not be employed = 
it Sereda Ordinary magenta fluid may be prepared 

4 grain of magenta crystals in 7 fl. oz, of distilled 
water, and adding 4 fl. oz. of rectified spirit. The colour of « section 
stained with this may be preserved for some time by immersing it 
in a } per cent. watery solution of corrosive sublimate. 

‘oxin, which dyes the tissues generally of a beautiful garnet-red 
colour, should be used in a strong watery solution, and the sections 
must be well washed in water after staining. Tts chief use is in 
“double st 

For Rompe green staining the various anilin dyes padi 
pally used. They are, for the most part, however, rather fugitive 
their effects, not forming durable combinations with the nate 
stain. Some of them are soluble in water, others only in spirit ; 
and the selection between the dyes of these two classes will have to 
be guided by the mode in which the preparations are treated. ‘Those 
alyes ave for the most part best fixed by benzole ; and as the sections 
treated with this fluid may be at once mounted i in Canada balsam, 
there is greater probability of their colours being Be- 
sides blue and green, the anilin series furnishes a deep rich brown, 





438 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


tuberculosis, a layer of eae oe OE Perea be 
as before w covery dri Set F. 
BUS Nib ah conan tion of methyl-blue in alcohol, 0-2 c.c. 
of 10 per cent. solution of potash and 200 ¢.c. of distilled water. Into 
this put the cover with its surface of bacteria and leave for - 
four hours ; the fil will be coloured blue ; place a few drops of 


from all bacteria, with alcohol and oil of cloves, 
Gere r Henenge Gibbes gives a method 
‘or the same purpose a 
which has (eeintent valse! ‘Take of hydrochloride 2 
Gace blue 1 gem. ; rub them up in a Then 
dissolve oil, 3 c.c., in rectified 15 ec. ; add the it 


water, 15 ce. Keep in a stoppered bottle. 

In the way dry the sputum &e.on a cover-gliss ; a few 
drops of the stain are poured into a test-tube and warmed. As soon 
as steam rises pour into a watch-glass and float the on 
the warm stain ; allow it to remain four or five minutes ; or if we do. 
not heat the stain but use it cold, let it remain for at least half an 
hour, Wash in methylated spirit until no colour comes off ; drain, 
and then dry in an air-oven, and mount in balsam. 

Staining Bacteria in Tiseues.—To 100 parts of solution of caustic 
potash of 1: 10,000 add 30 parts of saturated alcoholic solution of 
methyl-blue. Filter, Stain section for one or two hours, wash 
out with acetic acid of } per cent. followed by water. 
with absolute alcohol clear with cedar oil, and mount in balsam. 

ible and Multiple Staining.It is needful to allude to this 
mode of staining tissues, because during the last ten years it has re- 
ceived much attention, and also because of its apparent 
as an aid to histological research, and the extreme beauty of the pre- 
parations that may be made by its means. Butin Ee 
means of investigation, it is of little value, It di tissues, 
hut not ina manner that will make any further knowledge of then: at 
all ible, For class and popular purposes it will obtain ; but it has, 
‘so far as can be at present seen, no future for the investigator, 

Very beautiful effects are doubtless produced by the simultaneous 
or successive action of two or three staining fluids, which will re- 
= ined pick out (so to speak) the parts of a section for which 

hey have special affinities. Thus, if a section through the base of 
the tongue of a cat or dog be stained with picro-carmino, 
and iodin green, the musele-fibres will take the first, the connective 
tissue and protoplasm of cells will be coloured by the second, while 
the third will lay hold of the nuclei in the superficial epithelium, 
serous glands, and non-striated muscle in the vessels ; further, 
the mucous glands will show a purple formed by the combined action 
of the red and groen (Gibbes).!' A very striking contrast of the like 
kind is shown in the double staining of the frond of a fern with log- 
wood and anilin blue, the «ori taking the latter, and standing out 


} Seo his Practical Histology, Chapter Y.; and his paper in Journ. of Rey. 
Microso. Soe, vol, iii, 1880, p, 890, 








‘chemi employed ; but certain 
eel testes ea ir vlalogial ‘nvestigution: the, following 
Pare a ee eg 

in water (1 gr. of iodin, 3 gra of iodide of 


Wr ontoniodile of a ad ‘tie i apie hye 
B. Chior-i sine is made ine 7 
chloric acid, evaporating to the ewiy of uiniate acid, in contact 
with metallic xine, and adding as much ic iodide as the solution 
will take up. Finally saturate with erystals, 

‘This is extremely useful for the detection of pure cellulose. The 
zine chloride converts cellulose into amyloid, which is then tarned 
blue by free iodin. Wood-cells, cork-cells, the extine of pace. 


and all lignified or ES membranes, are coloured " 
colours blue, but is rapidly disorganised, 
A weak solution will instantly detect tannin, the cell con- 


stances, both animal and vegetable, and is extremely useful in 
rendering some structures transparent, whilst others are brought 
into view, its special action being upon horny textures, whose 
component cells are thus rendered more clearly distin; 

t Dilute sulphuric acid (one of acid to two or three a of 
water) gives to cel/iose that has been LS Md ie with fodin 
a blue or purple hue ; also, when mixed with a solution of sugar, it 
gives a rose-red hue, more or less deep, with nitrogenous substances 
and with bile (Pettenkofer’s test). 

Sulphuric acid causes starch grains to swell and similarly affects 
cellulase, 

« Concentrated nitric acid gives to olbuminous substances an 
intense yellow. 

& Acid nitrate of mercury (Millon’s test) colours albuminows: 
substances red. 

» Acetic Acid, which should be kept both concentrated and diluted! 
with from three to five parts of water, ix very useful to the animal 





442 PREPARATION, MOUNTING, AND COLLECTION OF OECTS 


being formed of which it often difficult to get rid), or the 
Se was pristinerninclatiaapissaieel Stee heat of 
eet yin ge 
of the Se ee at es tot aatheao tbouriy ta dis- 
the resin thus obtained either in benzole or chloroform, but 


far preferably the former, the solution being made of such viscidity 
fas will allow it to ‘run’ freely. Hither of these solvents 


already cement 
wl it hasa wor 
wiih ens ¢o| be penetrated (by at ies shoreighly tala ig fer 
by the artificially prepared solution. ener eee 
com 


solution is peat ; and this may be made by combining with 


acetate of potass. 

8. Where the preservation of minute histological detail is not 
so much desired as the exhibition of Ia: structural features of 
objects to be viewed by reflected light nothing is better than dilute 
amrit, the proportion most generally serviceable being one of aleohol 
to four or five of water, and an even weaker mixture serving to pre- 
vent further change in tissues alrendy hardened hy strong . 

«. Salt solution 0-75 per cent. sodium chloride in water, 

L Fruit juice, white of an egg.—Simply filter. 

n- Syrup in which is dissolved 1 to 5 per cent. of chloral hydrate, 
or 1 per cent, of carbolic acid, 

@ Chloral Hydrate. A 5 per cont. solution in water, or 12 grains 





Of late years glycerin hag been | ® preservative, 
either alone, woemtling to the mahol at De, Hale oe anal 
with water, or mixed with gelatinous substances. It is much more 
favourable to the of colour than most other media, and 
is therefore useful as a constituent of fluids used for 
paecating repetaiia ioe in that atom eee ‘Tt has also the 
ina less degree than sesinin elsaney seed es tae eee 
that are pions peas: areca ec 


2. For preserving soft and delicate marine animals which are 
shrivelled up, so to speak, by stronger agents, the Author hax found 
n mixture of one of glycerin and one of spirit with eight or ten 
parts of sea-water the most suitable ive. 


3. For minute vi ble preparations the 

method, devised by Hantasch, is said to be peculiarly efficient ; A mix~ 
ture is made of three parts of pure alcohol, two parts of distilled water, 
and one purt of glycerin ; and the object, Inid in a cement-cell, ix. 
to be covered with a drop of this liquid, and then put aside undera bell- 
glass, ‘The alcohol and water soon ev: so that the glycerin 
Lsceapbesias Fy = earn penne ee dy Shenae 
and a second evaporation permitted, process being repeated, 

; until enough. gkyoerin is left, to. -81l the eal, whieh 
roe be coer nd ee oy piste ployed mounting 

lanada is one of the most uni ly em 

media ; very old hard balsam should be dissolved in ee 
ly. 


i 


benzole to make a thin solution, which should be carefull, 

Dammar.—Dissolve gum-dammar with heat in a mixture of 
equal parts of benzole and turpentine, and evaporate to a syrapy 
consistency, This is pleasant to use, but treacherous. The prepa- 
rations often subsequently ‘closed.’ 

Gum Styrax.—This is a resin which must be disolved in benzole, 
choloroform, or ether. It should have the consistency of olive oil ; 
ull the benzole must be evaporated before putting the cover on the 





1 Sea the Rev. W. W. Spicer’s Hi to the Collection and Preparation 
of Freshwater and Marine Alge, de, img 


i. * Nothing,’ is Mr. roa 
Saeah teh vekicie a? ii eeeemelcial ol recto Rennes elec tie Haat 
method, the form of the plant aod the colouring of the endochrome having ander. 
gone no change whatever, 








446 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 
cover in its place, with the diatoms downwards, touching the ting at 


fitting the 
epee eee before the insertion of the pipette 
squeezing the rubber eap | ; 
Ralsattng St ntten ede ‘t is well down, a small quantity of | 
rises in the inet Ts ‘alswithdca ind tambo 
th the tilted of the cover ; the slightest pressure 


en] — Cp nt eee ee between 
anid slide ; gently and firmly press it down and ring it 
glue and honey, 

Tn half an hour points of superfluous 
exuded, With a pair of tweezers wet a piece of blotting. 
hisulphide and absorb these away, plunging the 
water, The slides stiodid ‘cow De pot ade for a or 
they may receive two or three rit Combis geet ani stes 
be finished with sealing-wax or varnish, 

Tt often is quite impossible to predicate beforehand what preserva- 
tive medium will answer best for a particular kind of preparation ; 
and it is consequently desirable, where there is no lack of material, 
to mount similar objects in two or three different ways, 
each slide the method employed, and comparing the specimens 
time to time, so as ers the condition of each. 

‘n dealing with the small quantities of fluid 

media required in mount ob- 

jects, it is essential for the operator to be pro- 
vided with the means of transferring very 


small quantities from the vessels containing 
them to the slide, as well as of taking up from 
the slide what may be | superfluous upon 
it. Where some one fluid, such as diluted 
alcohol or the carbolic acid solution, is in con~ 
tinual use, it will be found very convenient to 


keep it in the small dropping-hottle represented 
Fie, 361, in ty. 361. The stopper is perforated, and 
Dropping-bottlo. elongated below into a fine tube, whilst it 
above into a bulbous funnel, the 
of which is covered with a piece of thin yulcanised indiarub! 
firmly round its lip. If pressure be made on this i. 
pe of the finger, and the end of the tube be imm 
liquid in the bottle, this will rise into it on the 
finger ; if, then, the funnel be inverted, and the pressure 
plied, some Fd eee air will be forced out, an that 
immersing the end of the tube, and removing the pressure, 
fluid will enter. This operation may be repeated as often 
he necessary, until the bulb is entirely filled ; and when it 
charged with fluid, as much or as little as may be needed i 


= 
et 


it 
ij 


i 
£3 


uf 
Efe 


H 


chad ny # 
iid ceesist 


if 





tome, or mem! by dissection, do not require to be 
1 Sifenel hem nen ‘viscid medium ; since its tena- 
serve to keep off injurious i 

When the has been immersed 

liquids, is to be mounted or 
Farrants’ medium, the best mode of it on the cover is to float 
it in a saucer or shallow capsule of water, 

it, and, when the lies in a suitable above it, to raise 
the cover cautiously, the in by a needle, until it 


to adhere) or to leave any loose on the slide. Before 

object is covered, it should be looked at under « dissecting or mount- 
eng oeroscope) fees the pares rok Sa eore (if desirable) its 
disposition on the slide, and removing any Sree eee 


prea toler it aay it eaoogh of the sendeon hax bats ee 
fore it, if enoug! the medium has 

the whole space beneath the cover will be filled, and the object com- 
pletely saturated. If air-bubbles should unfortunately show them- 
selves, the cover must be raised at one margin, and a further quantity 
of the medium deposited. 

Tf, again, there are no air-bubbles, but the medium does not 
extend itself to the edge of the cover, the cover need not be raised, 
but a little may be deposited at its edge, whence it will soon be drawn 
ain by capillary attraction, ially if a gentle warmth be 
to the lide, It will then be advantageous again to examine the 
preparation under the rmbt rey ; for it will often 
‘that an opportunity may thus be found of spreading it better by the 
application of gentle pressure to one part or another of the 
fae which may be done without injurious effect either with a 
needle or by a pointed stick ; a method whose peculiar value, when 
viscid media are employed, was first pointed out by Dr, Beale. The 
slide should then be set aside for a few davs, after which its mount- 
ing may be completed. Any excess of the medium must first 
he removed, If glycerin has been employed, much of it be 
drawn off by blotting-paper (taking gare oot to touch tha MAigueh da 
cover, as it will be very casily displaced); and the remainder may be 
washed away with n camel's-hair brush dipped in water, which may 
be thus carried to the edge of the cover. The water having been 
drawn off, a narrow ring of liquefied glycerin jelly may be made 
avound—not on—the margin of the cover (according to the suggestion 
of Dr. 8, Marsh) for the purpose of fixing it the cement is 
applied ; and when this has set, the slide may be placed on the turn- 


tt 








450 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 





ir can 

carefully upon the cover, either by ‘scattering’ or * m 
and then to drop on to the whole cover and its objects as 
much Talaces 8 cover will receive without phen anh reo 


Z 
; 
: 
2 


by 
oil of t ming pend Meee eeepc ee eee ona 
a rasalighas? the object taken up in the forceps is to pees 
blest of ss clan that tho spring lop sth ring gre gh 
objects ing-elip 16 aprrit 
See ol ts holding siren tne cores eatlltbe tate jaa ty 
sufficiently to prevent its being lifted by the elasticity of the obj 
sbjects (such as the palates of gasteropods) which have 

prepared by dissection in water or weak ee may be ads 
mounted in balsam ; for which must be first, 
and then transferred from rectified spirit into turpentine. Carbolie 
acid has been recommended by Dr, Ralph! as most efficient in 
drawing out water from specimens to be mounted in balsam or 
dammar, which afterwards readily take its place. Sections of horns, 
hoofs, &e. which afford most beautiful objects for the polarixcope, 
best mounted in natural balsam, which has a remarkable 
increasing their transparence. It is better to set aside in a 
place the slides which have been thus mounted before at 
to clean off the superfluous balsam in order that the covers may be 
fixed by the eraie arg of isons at fo a 

Mountii jects jueous Liquids. —By greater: 
number etieovarstseas which are to be in li however, 
should be mounted ina cell of some kind, which forms a sell of 
suitable depth, wherein the preservative liquid may be retained, 
This is absolutely necessary in the case of all objects whose thickness 
is such as to prevent the glass cover from coming into close approxi- 
mation with the slide ; and it is desirable whenever that 


1 See the nccount of Dr. Ralph's method in Journ, Roy. Miorove.’Soe. vol. iii. 
1890, p. 868. 


A 





MOUNTING 45h 






bu bblesthe useof an air-pump is commonly recommended ; 
Author has seldom found this answer thepurpose satisfactorily, 


+ Quekett Journ. second series, vol. i. p. 40. z 
aa 





452 PREPARATION, MOUNTING, AND COLLECTION OF OBJECT 


fnd is much disposed to confidence in t ecom- 

sent es attain ea 

boiled water, has great power of « 

or Where the structure is one which ee 
alcohol, steeping in this will often have the same 
next point of i is to select a cover of a size exactly 

suitable to that of the ring, of whose breadth it should cover about 


be 

of grit, and then on a Water- 
Pia aia anccte el rep te 

Tf glass rings are not found to 

down with fine emery on a plate of lead. When the cell has been 
Hina Ralsied of Uy crust he axptully ulated Cosine eee 
Wotae’OF ts inounting Haid pane Mien cae = | under the 
dissecting microscope for minute air-bubbles, w! often to 
the bottom or sides. Thad Lachag beaeaet Salat eetegese 


easily made ie by inding wth water St om pee 
flat 


the cell should be finally filled with the preservative liquid, and the 
object immersed in it, care being taken that no air-bubbles are 
carried down beneath it. The cell being completely filled so that the 


Basin Seance eee tease Ee ee ee down 
cell be 


it as in the ling case ; or, if the 

cover may be Se ee Oe ee fi 
sa lguld ray be Jn by Me eyziigs: the other edge 
is lowered. on the cover is in place, and the liquid expelled from 
it has been taken up by the syringe, it should again be examined 
under a lens for air-bubbles; and if any of troublesome 


intruders should present themselves beneath the cover, the slide 
should be inclined, so 5 to cause them to rise towards the highest 
part of its circumference, and the cover slipped away from that part, 80 
as to admit of the introduction of a little additional fluid biter Ap ined 
ov syringe ; and when this has taken the place of the air- the 
cover may be bie back into its place. The surface of the ring 
and the edge of the cover must then be thoroughly dried with blot- 
‘ting-papor, care being taken that the fluid be not drawn away from 
botween the cover and the edge of the cell on which it rests. ‘These 
minutiw having been attended to, the closure of the cell may be at 
once effected by carrying « thin layer of gold-size or dammar around 
and upon the edge of the glass cover, taking care that it touches 
every point of it, and fills the angular channel which is left its 
margin. The Author has found it advan 8, however, to iy 
closing the cell for some little time after the superfluous fluid has 
been drawn off ; for a8 soon as evaporation from beneath the sige 
of the cover begins to diminish the quantity of fluid in the cell, 

bubbles often begin to make their appearance which were ly 
hidden in the recesses of the object ; and in the course of half an 
hour considerable number are often collected. The cover should 





454 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 
What is ited is: p of rece! 


thechief points of characteras wellas an object. 

‘The Editor has found the following plan to be hitherto, 
years’ trial, quite faultless, 

‘Let the slips which are to be used for mounting have the twoends 

of the surface finely ground ; at one end the ground surface 

may be uarters of an inch, and at the other end half an inch. 


it on over the 
and © surface will be wholly restored, and the will be 
i le. Tf cf bedi Foto 


whitened it will render still more easy the instant reading of the 
onthe grinding of th slips ia b difficult, and could 
‘indi 16 sli) no means it, not 
be costly if ifeew areanve dertsodltce SSiard 
It is ensy, however, to do all that is required. A block of wood 
se eece te the nlide 2h a exe ee oe Ore eer ee 
piece of wood half an inch thick, of the exact (1# inch) 
of the between the labels, enables a lead ‘ * to be freely 
used with fine emery and the work is speedily done. Of course the 
finer the emery the finer the surface ; and the finer the surface the 


‘This method gives a little more trouble and is slightly more expensi’ 
but in elegance and above all in durability we believe it has no: 
For the preservation of objects, the pasteboard boxes now at 
a very reasonable cost, with wooden racks, to contain six, twelve, or 
twenty-four slides, will be found extremely useful. For the ras 
ment of a large collection the following has proved itself to 
thoroughly practical, and can be iaciveraly prey ‘The species, 
genus, and character of the slides may be disregarded. Place the 
slides in the cabinet just as they come, numbering each consecutively. 
‘The exterior of cabineta should show from what number to what 
number the cabinet contains : thus, 527 to 842. The porcelain slab 
on the drawer may indicate from what number to what number the 
drawer contains ; thus, 527 to 539, Now a number of notebooks 
should be procured, so that there may be a separate notebook for 
each subject ; the size of the notebook must be to the 
importance of the special department the collector taken up. 


2 








456 PREPARATION, MOUNTING, AND COLLECTION OF OWECTS 


‘ Coutectiox or Onszcrs. 
A large of the with which the microsoopist 
Foran a arheron gr e phineniawide yr nierond 
vegetable or animal, the collection of which does 
not require other methods than those pursued by the ordinary 
Satis. regard to such, therefore, no special directions 
are required. praise imeam ean ead 
OP ar cacuitcany esomnlaliy Seeeeieip anne laser 
these i methods and implements, which are, however, 


tions only will be given ; the particular detai 
being reserved for the account to be hereafter given of each. 


the microscopic organisms in question, which inhabit 
fresh water must be sought for in ditches, or streams 
which some of them Se eT aes aoa tees 


‘to the stems and leaves of aquatic plants, or even to pieces of stick 
or decaying leaves, dc, that may be floating on the surface or sub- 
merged beneath it ; while others, again, are to be sought for in the 
muddy sediments at the bottom. those which have the 
free motion, some keep near the surface, whilst others swim in the 
deeper waters ; but the situation of many entirely upon the 
light, since they rise to the surface in st ing and ‘edleaia Spats 
rds. The collector will therefore require a means of 
samples of water at different depths, and of drawing to 
postions of the larger bodies to which the microscopic organisms ma) 
attached. For these purposes nothing is so convenient as the. oa 
stick, which is made in two lengths, one of them sliding within the 
other, so as when closed to serve as a walking-stick. Into the 
extremity of this may be fitted, by means of a screw socket, (1) a 
cutting-hook or curved knife, for bringing up portions of 
oe in order to obtain the minute forms of vegetable or animal 
ife that may be parasitic upon them ; (2) a broad collar, with # 
screw in its interior, into wl is fi one of the screw- 
bottles made by the York Glass Company ; (3) a ring or hops a 
ing at the sur- 
below the 


& 


muslin ring-net. When the bottle is used for coll 

face, it should be moved sideways with its mouth 

water ; but if it be desired to bring up a sample of the liquid from 
below, or to draw into the bottle any bodies that may be loosely 
attached to the submerged plants, the bottle is to be plunged into 
the water with its mouth downwards, carried into the situation in 
which it is desired that it should be filled, and then suddenly tarned 
with its mouth upwards. By unscrewing the bottle from the collar, 
and screwing on its cover, the contents may be securely preserved, 
‘The net should be a bag of fine muslin, which may be simply sewn 
to a ring of stout wire. But it is desirable for many purposes that 
the muslin should be made removable; and this may be 

for by the substitution of a wooden hoop grooved on its out for 
the wire ring; the muslin being strained upon it by a ring of 





458 PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 


When Polyzoa, Plumatella, 
Fredericella, it is advisable to examine the of trees growing 
at the edge of the water, and also to drag up weeds from the middle 
ee hook and line, 


prolonged by i eae 
made by crushing some anacharis, or Meret wood, eal 
mortar in a little water, which is then filtered through muslin, 
‘They can be seen to feed on this under the microscope, their tin; 
stomachs soon becoming filled with little balls of chlorophyll. 

Under favourable conditions Melicerta, Stephanoceros, the Flos- 
cules, and also Asplanchna, and other forms, breed and multiply in 
the aquarium, and can then be preserved for a considerable time. 

A little mud taken from a pond in winter or early spring, and 
put ina tank at home, will often produce an unexpected number 
and variety of rotifers and infusoria, which are hatched from 
winter eggs and dormant 4 

‘There must of course Sars in every tank between the 
animal and vegetable life, or aération must be maintained, 
So also food must be obtainable by the organisms, however small. 
But experience alone is the perfect teacher in this matter. 

‘The same general method is to be followed in the collection of 
such marine forms of vegetable and animal life as inhabit the 
neighbourhood of the shore, and can be reached by the War 
But there are many which need to be brought up from bottom 
by means of the dredge, and many others which swim freely 
through the waters of the ocean, and are only to be captured by the 
tow-net, As the former is part of the ordinary equipment of every 
marine naturalist, whether he concern himself with the Leger ts 
or not, the mode of using it need not be here described ; but 

2 ras 5 ’ 
fron the Trams, Midaleene Bate Huss Son. Sos ae Un nee 





CHAPTER VIII 
MICROSCOPIC FORMS OF VEGETABLE LIFE—THALLOPHYTES 


be cpg bedle arith ered rom ira Sateen 

appearan to i ‘ity in microscopic manipulation, 
eo to eaken tine perrpete Eoap ered grt sero 
by the study of those humblest of vegetation which present. 


ee ivag en 
are identical in plants und in animals, and that the living substance 
which exhibits them is of a nature essentially the same 
both ki is. Thedetermination of this general fact, which 
the basis of the science of Brotoey, is the most rtant result of 
modern microscopic inquiry ; and the illustration of it will be 
constantly in view, in the exposition now to be given of the 
jlications of the microscope to the study of minute proto- 
sitar araplast forms of plant-life), with whose form and structure, 
‘and with whose very existence in many cases, we can only acquaint 
ourselves by its aid, 
It was formerly supposed that living action could only be ex- 
hibited by organised structure. But we now know that all the 
‘essential functions of life may be earried on by minute ‘j id 


in whose apparently homogeneous semi-fluid substance like 
« nisation’ can be detected ; and, further, that even in the very 
highest organisms, which present us with the test of 


‘differentiated’ structures, the essential part of ‘the life-work is 

by the same material—these structures merely furnishing the 
mechanism (so to ) through which its wonderful 
exert themselves. Hence this substance,' known in vegetable 


+ Attention wns druwn in 1886 by Dujaniin (the French aoologist to wham we owe 

the transfer of the Foraminifera from the highest to the lowent place among in 
Lente animals) to the fact that the bodies of some of the lowest members of the 
animal kingdom consist of a structureless, semi-thuid, contractile to which 
in gare the namie aareode (raimentay Hoa). Tn ih the eninent bana Von 
T showed that « xiuilar substance forms tho essential cooatituent of the celle of 
lant gad termed i protoptanm Qrimitive plaatic or organinable material). And in 
Ts68 it was pointed out by Prof, Max Schultee, who had made w special study of the 
bt ore 


thizopod that the ' sarcode ‘of animals and the "of 
identical.” Bea his memoir Ueber das Protoplasma der Hhisopoden und Pflansen- 


i 





first stage in their production. Such is the case, 

(flowering plants), with the leafless ‘parasites’ w! draw their 

Seer heat the tissues of their ‘hosts.’ And it is the case also, 
3 


among the lower copelenans, with the entire of Foxar 
which, however, in a large number of cases, depactl rate for their 
nutritive materials upon organic matter in a state of decom; y 
many of them having the power of promoting that process 
symotic (fermentative) action, Among animals, again, there are 
several in whose tissues are found organic compounds, such as chloro- 
phyll, starch, and cellulose, which are characteristically vegetable ; 
but it has not yet been proved that es care these compounds 
for sersnieetts the decomposition my ye Ie 

‘he plan of organisation recognisable throughout vegetable 
kingdom presents this remarkable feature of uniformity, that) the 
fabric, alike in the highest and most complicated plants and in the 
lowest and simplest s of vegetation, consists of nothing else 
than an ogaregetion of the bodies termed cel/s, every one of which 
{save in the forms that lic near the border-ground between animal 


3 





Foutual connection, but. go through a. progressive ‘differentiation,’ 
the ordinary ‘ot the cell in Sead ola oars 
| described in proper place. composite structure is thus de- 


‘The contents of the plant-cell, which may be collectively termed 
(. to the ‘endosare’ of rhizopods), or, when 
fonkigt inthe fret place of an outer layer of protoplamn _ 
consist in an ou’ proto, ‘ic substance 
‘called primordial ag parictalutricle. Thia ian 
extremely thin and delicate layer, so that it escapes attention so long 
as it remains in contact with the cell-wall; and it is only brought 
into view when separated from this, either by developmental changes 
We She). or by the influence of reagents which cause it to con- 
‘by drawing forth part of its contents (fig. 364, C). It is not 
sharply delined on its in face, but passes gradationally into the 
inner mass of from which it is chietly distinguishable by 
the absence of granules ; and it is shown by the effects of reagents 
the albuminous 


bebars Saat jempouticn of protoplasm. It may thus be 
Jayer with which 


if 
3 
i 


ly external film of the protoplasmic 
inner surface is in contact; and it essentially 


as 





464 MICROSCOPIC FORMS OF VEGETABLE LIFE 


‘corresponds with the ‘ectosarc’ of Ameba or any other 
‘The ‘ectoplasm’ and ‘cellulose wall’ can | y 


PI * iy 

scopist of all its manifestations of vital activity, The nucleus is a 
small 5 usually of lenticular or eh ear’ form (ie. 364, A, oh 
and of albuminous composition, that lies imbedded 

substance, cither on the cell-wall or nearer the centre of the cavity. 
It is not, however, folsaady ene even in the higher forms of 
cell-structure ; for in those whose active life has been completed, 
the nucleus is usually absent, having probably been resolved 

into the protoplasm from which it was originally formed. in 
the cells of some of the lower cryptogams it has not at present been 
distinguished with certainty at any stage of their existence, Colls 
containing a number of nuclei, or ‘ multi-nucleated calls,’ are not un- 
common, They occur, for exawple, in many alge, in the ‘suspensor ” 
and ‘embryo-sac’ of the ovule of phanerogams, and in the ‘latici- 
ferous’ tubes. Within the nucleus are often seen one or more small 
distinct particles termed nucleoli (fig. 304, A, 6), which can be best dis- 
tinguished by the strong coloration they receive from a twenty-four 
hours’ immersion in carmine, and su ent washing in water 
slightly acidulated with acetic acid, Though in some points the pre- 
cise function of the nucleus is still unknown, there ean be no doubt 
of its peculiar relation to the vital activity of the cell ; for, in the 
nucleated cells which exhibit ‘cyclosis,’ it may be observed that 
if the nucleus remains attached to the cell-wall, it constitutes a 
centre from which the protoplasmic streams diverge, and to which 
thoy return ; whilst if it retains its freedom to wander about, the 
course of the streams alters in conformity with its position. But it 
is in the multiplication of cells by binary subdivision which will he 





— 


466 MICROSCOPIC FORMS OF VEGETABLE IVE 


each other, the endoplism of the parent-cell collects round the two 
new centres, 80 a8 to divide itself into two distinct masses (C, a, a’) ; 

and by the investment of 
these two secondary ‘endo- 





oo was " plasm. 
Pept teeta te ama thee” cass intend 


correspond 
masses round the tw: of noth and form 
Saar Ds Lao compote edhe niin octien, enother iin 
coll, divided by w partition, 


(lig. St) Sab one 

nfo 
pendent cell, without 
any investing cell-wall 
of cellulose, hence a 









Via. 906 —Gnccesaive’slagee of freecell formation echiot ee 
ih embryo-ase of aced of scaflet-runner: a, a, a, 0¥D Nucleus, formed 
completed ces, each | having ite proper cal. wal by Seabees of the 
nucleus, and endoplasin, lying im a protoplasmic nucleus parent- 
iRidiou singer of endopeeent eell; nd thera secon: 

dary cells, in various 
stages of development, lie free within the cavity of the parent-cell, 
imbedded in its residual endoplasm, each proceeding to complete 











468 MICROSCOPIC FORMS OF VEGETABLE LIFE 


‘hyaloplasm’ and of imbedded granular structures or ‘n 
A distinct substance, known as ‘nuclein,’ absent from 
plasm, appears to enter into the composition of the nu 
division of the nucleus may take place either directly 
process is known as ‘ fragmentation’ ; or indirectly, In 
of indirect division, the protoplaam of which the nuck 
posed undergoes a great variety of changes, in the coun 
it assumes the beautiful appearance known as the ‘nuck 








i 


EF 


which 
formed, 
ng that 


ies multiplies by binary 

ww pair that. Reel by division 
a complete separation from one another, 
i itly ; but if, instead of under- 
ey should be held together by the 

a shapeless mass results from re- 
ere on any determinate plan ; 
ivision should always take place 
narrow filament (fig. 374, D), or 

flat, leaf-like expansion {o) 
feSpeat fabrics the term ee r’ 

iety ; since they muy 

or wuillions of "atingt cells, whiel 

wate from cach other spontaneously. 
jose which are strictly unicellular, as to 








and no. of mutual. r i ong them ; and 
general term of 1 bre tote ove & 4 
chloroph; can themselves upon air, water, and mineral 
matters 5 afar mtiou sor c Al for themselves, 
depend for their nutriment upon drawn from other a 
isis, Each series sap ne of forms, which, 
traced from below upwards, increasing com- 
plexities of structure ; and these show themselves espe- 
cially in the provisions made for the ‘in 
some forms, a © "is the of the contents. 
OE bo alle, Wha ater it uny sexual difference, the one 
from the other, nor can be in any way from the rest. 
Tn the next highest forms, while the ‘con| cells are still 


ale cell, whose contents, i with the 
material they bring, form an ‘odspore.’ In the lower forms of this 
stage, cells are not from the 


This must, however, be dis- 
tinguished from organs which, though commonly spoken of as the 
7 fraotifiostiony diane no real analogy with the generative 
of flowering its, their function being mer ages se 
gonidial ' cells or groups of cells, which simply iply the parent 
stock, in the same manner that many flowering plants (such as the 
aes De propagated ty. the sialon patente their 
ds, It frequently hay among eryptogams that this gonidial 
fructification is by far the more conspicuous, the sexual fructificn~ 
tion being often so obscure that it cannot be detected at all without 
great difficulty ; and we shall tly see that there are some 
thallophytes in which the prontastiba of gonids seems to go on 
indefinitely, no form of sexual generation having been detected 
1 The term gunids, originally appliod to certain green cells in the 
‘that are capable, when detached, of pone cite ‘Tegetative portion 


z 


‘of the plant, 
in used by some writers aa a do 


of 
which it iv wery i to discriminate from the: ive ' G 
pe ce el Pp php rer sth eat ‘ar 
account of the regeerns they prowint when a number am set free at ee 
‘erarmpotes’ I Sentraitineion nto mati" gon ox saporsa aaa R 
(OW nO moverNENt axv often termod resting apores, oF Aypnopores ; but wuch 
Githec seroal soaphores cr Wowassual gontde’ the inihens tae Minion eae ie 
cysting’ themselves in « firm envelope, and then remaining dormant for long periods 
time, 


Fra. 869.~Development of Protococeus pluviatis. 


like a particle of dust, yet resumes its vegetative activity whensver 
placed in the conditions favourable to it. The conjugating process 
commences by the putting forth of protrusions from the boundaries 
of two adjacent cells, which meot, fuse together (thereby showing 
the want of firmness of their ‘ ectoplasms ’), and form a 

bridge between their cavities (K). The fusion extends before 
through a large part of the contiguous sides of the two cells (L) ; 
and at last becomes so complete that the combined mass (M) shows 
no trace of its double origin. It soon forms for itself a firm cellulose 
envelope, which bursts when the ‘zygospore’ is wetted ; and the 
contained cell begins life as a new generation, speedily multiplying, 
like the former ones, by binary subdivision. It is curious to e 
that during this conjugating’ process a production of oil particles 
takes place in the cells; these are at first small and distant, bat 











E 
3 
E 






cere 
a 


i 
il 
HE 
g, 
ih 


‘motile’ cella ; others produce a firm cellulose env: and become 
‘still ' cells ; and others (perhaps the majority) perish without any 
further change. 

When the ordinary division of the‘ still " cells into two its. 
has been repeated four times, so as to produce sixteen cell 
sometimes at an earlier period—the new cells thus produced assume 
the ‘ motile’ condition, being liberated before the development of the 
cellulose envelope, and becoming furnished with two long vibratile 
flagella, which seem to be extensions of the colourless - 
layer that accumulates at their base so as to form a sort of trans 
ig beak (H). Tn np condition it rar agro that the colour 
jess jasm is more devel relatively to the colouring matter 
arith the * still” ear it Heft contains * vacuoles ” 
occupied only by clear aqueous fluid, which are sometimes 80 
numerous as to take in a large part of the cavity of the cell, so that 
the coloured contents seem only like a deposit on its walls, Before 
long this ‘ motile’ cell acquires a peculiar saccular investment, which 
seems to correspond with the cellulose envelope of the ‘still’ 
but is not so firm in its consistence (I, K, L) ; and between this 
the surface of the ectoplasm a considerable space intervenes, tra- 
versed by thread-like extensions of the latter, which are rendered 
more distinct by iodine, and can be made to retract hy means of 








476 MICROSCOPIC FORMS OF VEGETABLE LIFE 


ef 


some time the number 


reaches, as before, an ary amount ; 






Hl 





mena 
ile Hf aa 
lat 
fl ue 
ita 
ngiliil 
bale 
nBiaid 


fi 
i 
i 
i 
Al 


they collect themselves at the surface of the water and at 

edges of the vessel, but when they are about to segmen- 
tation or to into the ‘still’ condition, they sink to the bottom 
of the or retreat to that part of it in which they are least 
subjected to light. When kept in the dark the ‘motile’ 
a oat diminution of their eh! ll, which becomes very 
and is diffused, instead of forming detinite granules ; they 
their movement, however, uninterruptedly without either sinking 
to the bottom, or passing into the ‘still "form, or ipl fm 
mentation. A moderate warmth, particularly that of the sun, 
is favourable to the development of the ‘motile’ cells ; but a ter 
rature of excessive elevation ts it. Rapid evaporation of 
water in which the ‘motile’ forms may be contained kills them at 
once ; but a more gradual loss, such as takes place in deop glasses, 
causes them merely to pass into the ‘still’ form ; and in this condi- 
tion—especially Seda they have assumed a red hue—they may be 
completely dried "py and may remain in a state of dormant vitality 
for many years. It is in this state that they are wafted about in 
atmospheric currents, and that, being ras: down by rain into 
po cisterns, éc., they may present themselves where none had 
been previously known to exist ; and there, under favourable ciroum- 
stances, they may undergo a very rapid multiplication, and may 
maintain themselves until the water is dried up, or some other 
change occurs which is incompatible with the continuance of their 
vital activity. ‘They then very commonly become red throughout, 
the red colouring substance extending itself from the centre towards 
the circumference, and assuming an appearance like that of oil- 


fren F Kod nates seem to be favourably affected by 
ight, for 
the 





478 MICROSCOPIC FORMS OF VEGETABLE LIFE 


rest tae eee 
A); me they advance towards the 


axile direction. lopiih 


Pprtbeges pk paps pen ee 
cells of two distinet filaments TS happen 80 Bob Proximity 





Fro. $70.— Various stages of the history of a Spirogyra: A, three celle, ab ot 
oun flamouty af wish 8 fs asereein divin Bw lament 
cannon sowing the apa di of their endochromes and 
‘conjugating cal ‘comepleiion of the ust ‘of conjugation, 
the endochromes of the cells of the filament ahavingentirely passed over to thowe 
of filament 8, in which the zygospores are formed. 


hg between them 5 er it ees that they Ker so as to 
m the ‘zy re.” ut in the various species a 
870, B), ie among the commonest ad beat known ii { 
gate, the endochrome of one cell passes over entirely into the 
of the other; and it is within the latter that the ‘zy; 
see ©, the oe endeared ee EPs) a sim; 
around which a firm envelo; wally makes its 
Farther, it may be general. A ci that all the calls Ten 
filament thus empty themselves, whilst af” the cells of the other 
filament become the recipients. Here, therefore, we seem to have a 
foreshadowing of the sexual distinction of the generative cells into 
‘sperm-cells' and ‘germ-cells,” which we shall presently see a 
filamentous Confervace. Conjugation between two ea a cells 
the same individual also occurs in some species. 
*zodspores ' does not take place among the Sonfegater 


pan 








Fro, 871.—Structure of Volvor globator. 


and that of the motile ‘encysted ’ cell of Protococous pluvialis (fig. 
369, K). There is not, in fact, any perceptible difference between 
them, save that which arises from the regular tion, in Fofvox, 
of the cells which normally detach themselves from one mnother 

Protococeus. ‘The presence of cellulose in the hyaline substance 
not indicated, in the ordinary condition of Voleoa globator, by the 





a =a 
482 - MICROSCOPIC FORMS OF VEGETABLE Lire 


‘membrane. On the other hand, the i hreads are some- 
times seen as double lines, which seen like tub : 





cell (c), which is prelimi: to its binary subdivision. A more 
aiivanbed| stage of tha exis evelopmdntal proces iwvari gina | 
which the connecting processes (a, @) are so much increased in size 
as to Stabieh a most intimate eae between the masses of | 
chrome, although the increase intervening hyaline substance | 
Sere iheea eacotonst Pets eae euies ee eieetka cede aaE ] 
of the central globular cell has undergone segmentation into two 
halves. In the stage represented in No. 4 the masses of endochrome 
have been still more wi a by the interposition of hyaline 
substance ; each has become furnished with its pair of Hla ; and 
the globular cell has undergone a second itation. in 
No. 5, which ba © por tice ofthe apheriaal itl OO fan oa 
Volwox, the hrome masses are observed to present a. 
eng ag] hl on pees their own reduction in 
and rough the interposition of a greatly increased amountof 
Iiyal eo rata cies 2s eucrobedl cea Abecea et each 
and that portion which belongs to each cell, standing to the 
chrome-mass in the relation of the cellulose coat of an ordinary 
to its ectoplasm, is frequently seen to be marked out from the 
hy delicate lines of hexagonal areolation Rp which indicate 
boundaries of ench, Of these it is often lt to obtain « 
a nice mm it of the light being usually requisite with 
specimens ; but the prolonged action of water ( i 
contains a trace of iodine) or of glycerin will often bri: 
clear view. The prolonged action of glycerin, moreover, will 
show that the boundary lines are Risin being formed by | 
coalescence of two contiguous cell-walls ; and they sometimes retreat | 
| 


an d 


: 


qepaeklis 


ct 











484 MICROSCOPIC FORMS OF VEGETABLE LIFE 


red aud of a long, colourless beak, from the base of which 
ponsre scene ec ee 
the naan a tony beanies Ohne i, teak 


size wit Scbatrinoe inh Stee shows Jarge recites 
sin their protoplasm (6% £2), but subsequent] with 
ean erleiese. ate ee 2 


vent-sphere breaks up, snp the coepsee Ta to the bottom, where 
eae remain during the winter. ir 
heen traced out by Kirchner, who found that their germination 
commenced in February with the liberation of the spherical ‘ endo- 
spore’ from its envelope, and with its division penis: the 
formation of two partitions at right angles to each other. 
partially separate, nolan together only at one end, which becomes 
one pole of the globular cluster subsequently formed by cell-multi- 
plication, the other pole only closing in when a large number of 
cells have been formed. The cells are then carried apart from one 
another by the hyaline investment formed by each, and the cha- 
racteristic Volvor sphere is thus completed.' 

Another phenomenon of a very remarkable nature, namely, the 
conversion of the contents of an ordinary vegetable cell into a free 


lootrine of the vegetable nature of Volvo, which had hewn pease f 
first distinctly: 4 
vere in ike Prana a 


of the various forme of 











ld rather seem 
a Souk coe onan Pane enlace 


under the name of ‘gory dew,’ is hatte 


Fie, S72 —A, conjagaling times extending itself over a a ep pas 
maicrosocspores area as a h, gelatinous epee ie 
ce iiete eer: colour and general appearance of 

“Physiology of Plants,’ blood. A characteristic illustration of it is 

also afforded by the [remeatococons 

(fg. 373), which chiefly dite from Palmella in the partial 

of the walls of the parent-cella, so that the whole mass is sulslivided 

by partitions, which enclose a larger or smaller number of cells 
Seine in the subdivision of their contents. Besides i 

e ordinary mode of binary multiplication, the Palmalle cells seem 

Sa aATE to rupture and diffuse their granular contents through 

the gelatinous stratum, aud thus to give origin to a whole cluster at 

once, a5 seen at ¢, after the manner of © simple plants to be 
presently described, save that these minute segments of the endo- 
chrome, having no power of spontaneous motion, cannot he ranked 
as ‘zoispores.’ The gelatinous masses of the /’almella are frequently 
found to contain parasitic growths formed by the extension of other 
plants through their substance ; but numerous branched filaments 
sometimes present themselves, which, being traceable into absolute 
eontinuity with the cells, must be Scnatcaeel as properly appertaining 





on which the | wdetinite mem- 
studying the | , Some 

bed Ms of which are seen in fig. 374, od 
calls A, in wl it originates, in all points those of a 


directions to clusters ax those seen at Band ©, or to 
such converfoid filaments as that shown at D. A 
the same mode of subdivision, in 
two directions, may at once extend the clusters B and C into 

5 Ot; 


uf 
a! 
Fr al 
Hu 


iHLEE 
iat 
Hy 
unl 


PIG: 
S 
e 


wth and reproduction. 
. : cell is 





Fro. 974. —Successive stages of development shows the froups of 
of Uloa, arranged in clusters contain: 


Besides this continuous increase of the individual frond, however, 
wwe find in most species of Ulea a provision for extending the 
by the dispersion of ‘zoospores.’ sla piet re 75, a) aub- 
divides into numerous segments (as at 4 and ¢), which at first are 
seen to lie in close contact within the cell that contains them, then 
begin to exhibit a kind of restless motion, and at last escape by. 
the bursting of the cell-wall, and they swim freely through the water 
ag zoospores (¢) by means of their flagella, either two or four 
belonging to each xodspore, with which they have become endowed 
during the formation of the zotspores within their mother-cells, At 





PLATE Vil 





Oscilariacewe and Seyicnemaceee 





if 
z 
in 
- 
t 
i 


i 
alu 
li 
i 
i 
fee 


| 
3 
i 
j 
j 
4 
i 


i 
; 
, 


FS 
2 
: 

Lice 


of opium, iodine, or other chemical 
spore continues for about two hours; but after the lapse 
time it soon comes to an end, and the spore begins to devel: 
into anew plant. It has been observed by Unger that 
of the zotispores generally takes place towards 8 a.m. ; to 
phenomenon, therefore, the plant should be gathered the day 
and its tufts examined early in the morning. The sume filament 
may give off two or three zolispores successively, 

5 Recent igor shown that there exists in years 

lant a true process of sexual generation, ns was indeed 
cael by Vaucher, though upon no sufficient grounds. The 
branching filaments are often seen to bear at their sides 
globular or oval capsular protuberances, sometimes by the 
interposition of a stalk, which are filled with dark endochrome ; and 
from these, after a time, new plants arise. Tn the neighbourhood of 
these bodies are found, in most species, certain other 
which, from being usually pointed and somewhat have been 
named ‘horns’ (tig. 877, A, a); and these have been shown 
Pringsheim to be ‘antherids,’ which produce ‘antheroxoids’? in 
interior; whilst the capsule-like bodies (A, 4) are Bie ial or 
‘archegones,* each containing a mass of endochrome wi consti: 
tutes an ‘ oiisphere” that is destined to become, when fertilised, the 
original cell of a new generation. The antherozoids (B, ¢, a) 


Hor 
43 


# 


. 


PLATE Yul 





Tee Newman chron 
Seytonemaces, 


| Desmidiacem, Rivulariacece and 


—_ 














of being broken up into a 
number of distinct 
masses, which are at first 
in close contact with each 
other, and with the walls 
hich “gradual” tc 
wi 
‘more isolated, each 
to moquire a cell 
wall ; then Regia to 
move dl within the 
parent-cell ; and, when 
ole monture, they are set 
2 oes the rupture of its 
). STR —Development tA, forth, 
Titled extealty ott sear srarieiee Pea ee 
ER OO tee Peo 
filament afte te lla has bors, ond form cells resembling those 
Fes etait ass Seaton 1290 which thay 
{Zof granular protoplasm. Each 


of 
their movements are not so powerful as those of ths zotispores 
Vaucheria, and come toan end sooner. The generative process in this 
type is performed in a manner that may be as an advance 
upon ordinary conjugation, ‘The end of one of tubiform cells 
enlarges intoa globulardilatation, the cavity of which es shut off 
bya transverse partition. Its contained endoplasm divides into two, 
three, or four segments, each of which takes a globular form, and ix 


it ity for the production of chlorophyll, and ite Lage on the bodies of 

spiel fn einen Stee = ito an tho bodies of vag sh, wok 
to rol 1, & oy ‘itie on i 

ulag the yory Godt dloeas 12 'riSah exis urs acini aa 


i 
i 


&x 





HYDRODICTYON 495 




















by the penetration of an antheridial tube which comes 
the filament «4 little below the partition. The ‘oispores’ 
|, escaping from the globular cavities, acquire firm en- 
jand may remain unchanged for a long time even in water, 
riate nidue exists for them; but will quickly germi- 
dead insect or other suitable object be thrown in. 
of the most curious forms of the lower alge is the ‘ water- 
ictyon utriculatum, which is found in fresh-water 
the midland and southern counties of England. Its frond 
ef & green open network of filaments, acquiring, when full 
length of from four to six inches, and composed of a vast 
of cylindrical tubular cells, which attain the length of four 
more, and adhere to each other by their rounded extremities, 
of junction corresponding to the knots or intersections 
ymetwork. Each of these cells may form within itself an 
multitude (from 7,000 to 20,000) of ‘swarm-spores,’ which 
gertain stage of their development are observed in active 
in its interior, but come to rest in the course of half an 
then arrange themselves in such a way that by their 
they again form a net of the original kind, which is set 
the dissulution of the wall of the mother-cell, and attains 
course of three or four weeks the size of the mother-colony. 
these bodies, however, certain cells produce from 30,000 to 
“ microzoéspores ’ of longer shape, each furnished with four 
la and a red ‘eye-spot’ ; these escape from the cell ina 
and move freely in the water for some time. Quite recently 
ion between these sinaller ‘ zoispores’ has been observed by 
Port, taking place sometimes even with the mother-cell. The 
ing body or *zysospore’ retains its green colour, but becomes 
with a firm cell-wall of cellulose. In this condition these 
may remain dormant for a considerable time, and are de- 
as ‘hypnospores’ or ‘resting spores’; and in this state they 
fable to endure being completely dried up without the loss of 
vitality, provided that they are secluded from the action of 
which causes them to wither and die. In this state they bear 
resemblance to the cells of Protococcus. The first change 
& manifests itself in them, when they bein to germinate, is « 
enlargement ; next the endochrome divides itself successively 
distinct masses, usually two or four in number ; and these, 
set free by the giving way of the enveloping membrane, pre- 
the characters of ordinary ‘zoispores,’ each of them possessing 
fiagella at its anterior semitransparent extremity. Their motile 
ition, however, does not last long, often giving place to the 
stage before they have quite freed themselves from the 
ll; they then project long angular processes, so as to 
mame the form of irregular polyhedra, at the same time augment- 
§ in size ; and the endochrome contained within each of these 
‘aks up into a multitude of ‘zoispores,’ which are at first quite 
nt and move actively within the cell-cavity, but soon unite 
fos network that becomes invested with a gelatinous envelope, 
d speedily increases so much in size as to rupture the containing 


















MICROSCOPIC FORMS OF VEGETABLE LIFE 


trom which promt the ie 
arene et te ns Paar ee 


cells of f p A 

Site. Ceo ee 
im 3 A ‘ 

to a length of from y/yth to brd of an inch. ‘ ees 

m 


3 


ar 
goes 
a 


The bers family Pediastres were formerly included 
i Was, Datalcineei uik: s2pkagh flea Alea reletec ke fier fa eect 
partionlare, Shey. pesmi too akeay pons ofl etanoa ta bee eey 
Defer cn 

of its in either by the ‘jon of * ut | 
eaahing areola anp (lg, 380, ) 5 bak th flee ta thee toe 
important parti ti cells are not made up of two sym- 





F 10. 879.—Various phases of development of Podiastrwom grmuutatirm. 


metrical halves, and that are always found inaggregation, whiclr 
is not, except in such eens be ionc oa y sas eee 
with the Desmids, in linear series, but in the form of 
fronds. In this tribe we meet with « form of multiplication by motile- 
‘megazotspores’ which reminds us of the formation of the motile 
spheres of Volvor, and which takes place in such a manner that the 
resultant juct may vary greatly in the number of its cells, and con- 
sequently in sizaand in form. Thus in Pediastruns, 

(fig. 379) the ‘zosspores’ formed by the subdivision of theendochromeof 
one cell, which may be four, eight, sixteen, thirty-two, or sixty-four in 
number, escape from the parent-frond still enclosed in the inner layer of 
the cell-wall ; and it is within this that they develop themselves into- 
acluster resembling that in which they originated, so that the frond 
may be setts either of the just-mentioned multiples or sub- 
multiples of 16. At A is seen an old dis, of irregular seilgemed 
emptied by the emission of its ‘zojispores,’ which had secon, 











Pio. 450.—Various species (?) of Pediastrum: A, P. tetras ; P. Ehvontergii; 
in De preeliilis E, pomiepante ‘of P. pind ehus [ 


varieties are diffused by the process of binary subdivision 
vast multitudes of so-called individuals, Thus it hay as 
Mr. Ralfs has remarked, ‘one pool may abound with individuals of 
Staurastrum dejectum or aplcilanats inows having the mucro 
curved outwards ; in a neighbouring pool every specimen may have 
it curved inwards; and in another it may be straight. The cause 
of the similarity in each pool no doubt is that all its plants are off- 
sets from a few primary fronds.’ Hence the universality of any 
particular character in all the specimens of one gathering is by no 
means sufficient to entitle these © take rank ag im distinct species ; 
since they are, properly speaking, but repetitions of the same variety 
tvarmonsy oe Muay multiplication, really re in their 
entire aggregate the one plant or tree that grows from a seed. 
Almost every pond and ditch contains some members of the 
fumily Confervacex ; but they are especially abundant in moving 
water, and they constitute the greater part of those green threads 








EL ebiseecs * al D seis De eet 
ANE: Co antenay fs Ua 
Bs 3 Hag aes sin dhe 
ia! pet undulata 

Hi Hotere een 
AER feed RS A LEa eat 
PEPSI Le Hiab ot ema T rT aber sa ast 
AiR ry uate ili Lege Dna 


7 


500 MICROSCOPIC FORMS OF VEGETABLE LIFE 


zouspores, produced Spparentiy, todiferently from any cell 
ment, by free cell-formation. ese ZOU are of two ki 


xodspores 
or smaller ; the larger kind have either two or four cilia, 
nate directly ; the amaller are biciliated, and conjugation 
them has been observed in a few instances. 








502 MICROSCOPIC FORMS OF VEGETABLE LIFE 


ids on the other, and in the simplicity of the means by which the 
ee cool arene © and 
habit of life, but differ from them in some curious As 


the component cells of the filaments extend themselves longitudin- 

ally, new rings of cellulose are formed successively, and intercalated 

into the cell-wall at its upper end, giving it a ringed 

Only asingle zobspore ia set free from each cell ; libera- 

deere eed be ine alscoct complete Buacnice tho yall gb 2, 
A B 





Fro, 888.—A, Sexual ee of (Bdogonium ectliatum: 1, filament with tro 
coiigones in process of formation, the lowur one having two andrasporgs attached to. 
ita exteriar, the contents of the upper otgone in the uctof ferlilived by the 
entrance of an antheroaoid set free from the interior of ite 72 
untherowlds; 8, mature o¥ pore, still invested with the cell-mem! of the 
psrent-filament; 4, portions of a filament bearing special cells, from one of which 
an androspore is being set free; 5, liberated wndroxpore. 
B, Branches of Chetophora clegans,in the act of discharging ciliated 2o%spores, 
which are seen, as in motion, on the right. 
cell through one of these rings, a small part only remaining uncleft, 
which serves as a kind of hinge whereby the two parts of the fila- 
ment are prevented from being altogether separated, Sometimes 
the zolispore does not completely extricate itself from the parent-cell ; 
and it may begin to grow in this situation, the root-like processes 
which it puts forth being extended into the cavity, The 
are the largest known in any class of algw ; each has = nucleus, a 
red ‘ eye-spot’ and an anterior hyaline spot to which is attached a 
tuft of cilia visible even before its escape from its mother-cell. 
In their generative process, also, the Bdogoniacea: show a curious 
departure from the ordinary type; for whilst the ‘oospheres’ are 


EE 


EDOGONIACER; CHATOPHORACEAD 503 
formed within certain dilated cells of the ordinary filament (fig. 383 
A, No. 1), which may be « in oe fone rick 
of ‘antherozoids’ (No. 2), antherozoids are not, in all 
e LE pie eds octal the same or 


Fasastonacs Se whieh ere rm mth a spi call (No. 
os ; 
4), and which, i i ea anaes aaa h ae 


powers, very resembles an ordinary zotspore, 
after its of activity has come to an attaches 
retreated »of an Hed fa callin aia eee 
mity to an ng po Sunes aes ae 
small plant, asa ‘dwarf-male,’ consisting or 
Tiree calle thin tergcal oF thoeo oolla nian mirthorid foes the apes 


The coontitate «, Senutiful and intor esting little 
group of confervoid plants, of which some species inhabit the sea, 
whilst others are found in fresh and water—rather in that of 

ly moving streams, however, than flowing currents. 


: 
b 


into ‘zotapores,’ and these, when set free, are 
seen to be furnished with either two or four cilia. ‘ Resting- 
seen in many species. One of the most 
Yeautiful objects under the microscope is Draparnaldia glomerata, 
Bee opoames in still water, eases es oomrpreed of a 
single row Lana nee containing but a s1 quantity 
ts at is proceed, at regular intervals, whorls of 

slender branches, the endochrome of which is deep green, and ev 
branch ends in a delicate hyaline hair of extraordinary length. The 
oS DES eaaeen ‘of the Chetophorace closely resembles that of 
The Batrachospermete, whose name is indicative of the strong 
yesemblance which their bended filaments bear to frog-spawn, are 
‘now ranked as humble fresh-water forms of a far higher, chiefly 
marine group of alge, the Rhodospermem, or red sea-weeds. But 








two, or themselves si off 
lateral branches, the 
primary branches originates in 
a little protuberance from the 


primitive cell of the central 


render it an ierpedast ; 
=e and by the continual repetition 
10. 884. " 
Bairecerperum monitforme. — SE ie, roots oF nety sal 
converted into a beaded filament, Certain of these branches, how- 
ever, instead of radiating from the main axis, grow downwards upon 
it, 80 as to form a closely fitting investment seems pi to 
helong to it. Some of the rudiating branches grow out into 
transparent bristles, like those of Chetophoracen ; and within those 
are produced ‘antherozoids,’ which, though not endowed with the 
power of spontaneous movement, find their way to the odspheres 
contained in other parts of the filaments; and by the fertilisation 
of the contents of these are produced the somewhat complicated 
fructifications known as ‘cystocarps,’ placed in the axils of the 
branches (fig. 384). 

A very singular relationship, called by some writers an ‘alter- 
nation of generations,’ exists between Batrachospermum and Chan- 
trangia, « genus of fresh-water algw previously placed in a totally 
different section, This relationship was first described by Sirodot,* 


! Sirodot, Les Batrachorpermées, fo, 1881; see leo Comptes Hendwa, vol Ixxvi 
1678, pp. 1216, 1895 ; yal. xci, 1880, p86; yoL eel. ANN, pr Dike 














Pro, a45-—Nitella leslie: A. Stemand branches ofthe natural siz: th four 
‘the branches. 


ere of beanche inning, rom the alanis J, exbdiviaan of 

Paci te we ranches enlarge terplspent in 
o,f, now celle sprout ome the ai wit o LJ fom vem 5 new cella «prouting 
OY the extremities of the branches zt 


the young cells the rotation may be seen before this granular 
lining is formed. The rate of the movement is affected by 

that influences the vital activity of the Bey thus it is 

by moderate warmth, whilst it is retarded by cold; and it may be 
at once checked by a slight electric discharge through the 
Carried along by the protoplasmic stream are a number of 

ticles, which consist of starchy matter, and are of various 
being sometimes very small and I ex figure, whilst in other 


instances they are seen as la) which appear to 

be formed by the aggregation Sines the aeaacteat * The produc- 
1 Temomanon sam aking nal sal por 

tion @t ths plant one it tharmntoe tn whieh its growing, panes fl 


508 MICROSCOPIC FORMS OF VEGETABLE LIFE 


direction, by the lashing action of two long and very 

with which it is furnished. The exterior of the ‘nucule! 
formed by five or ten spirally twisted tubes that give 
peculiar aspect ; and these enclose a central sac contain 
plasm, oil, and starch-globules. Each of tliese tubes ¢ 
its lower part, of a very long unsegmented cell; #} 
upper part two small cells are segmented off ; and these) 








as due to an exudation of mucilage, and the first two to the forma- 
Moa) iartng the (aces le ee eee 

is temy ‘ily attached to the bottom, which gradually 
lengthens. 2 heim hoe ees sence 
they arein the process of dividing, Stahl move- 
Set rt wee LET Riel ueeees 
towards the light. 


A ‘cyclosis’ may be readily observed in many Desnvidiaces, 
and is parti lnely obvious eloog the convex tnd ecnoave edges of 
the cell of any us pwep erties ens 
power of 250 or dinmeters (fig. 387, A,B), By focus- 
ing the flow may be seen in broad streams over the whole surface 
of the endrochrome ; and these streams detach and with them, 
from time to time, little oval or globular bodies (A, 3) which 
forth from it, and are carried by the course of the flow to the trans- 
went at the extremities, where they join a crowd of similar 
ies. 2 each of these spaces (B) a protoplasmic flow proceeds 
from the somewhat abrupt termination of the endochrome towards 
the obtuse end of the cell (as indicated by the interior arrows), 
and the globules it contains are kept in a sort of twisting movement 
on the inner side (a) of the primordial utricle. Other currents aro 
seen apparently external to it, which form three or four distinct 


+ Untermuchs aus dem Bot. Inst. Tabingen, 1886, p. 888, 
2 Biologisches Contralblatt, 18s, p. 838, nage 


PLATE K 





; West. Newman chromo. 
Desmidiacez. : 








DESMIDIACER SIL 



















; passing and away from c (as indicated 
azrows). Another curious movement is often to be wit- 
interior of the cells of members of this family, which 
as ‘the swarming of the granules,’ from the ex- 

p resemblance which the mass of particles in active vibra- 
bears to a swarm of bees. It is especially observable 
Yerminal portions of the cells of species of Closterium, 
fig. 387, B. This motion continues for some time after 
have been expelled by are from the interior of the 
to bean heer cance the molecular movement 

minute icles suspended in fluid. This 

ef minute particles affords an Teatattoe of the phenomenon 
*Brownian movement,’ and is probably of a purely 


nature. 
the single cell has come to its full maturity it commonly 
iteelé by binary subdivision ; but the plan on which this 


is in Closterium lunula: A, cell showing central separation at a, 
large particles, }, are not seen; B, one extremity enlarged, showing 
of particles inthe colourless space; D, cell in a state of division, 


is often peculiarly modified, so as to maintain the 
characteristic of the tribe. In a cell of the simple 
form of those of Desmidium (tig. 391), little more is 
than the separation of the two halves at the sutural line, 
formation of a partition between them by the infolding of 

ial utricle ; in this manner, out of the lowest cell of the 
A, a double cell, B, is produced. But it will be observed 
of the simple cells has a bifid wart-like projection of the 
wall on either side, and that the half of this projection, 
been appropriated by each of the two new cells, is itself 
bifid, though not symmetrically ; in process of time, how- 
increased development of the sides of the cells which re- 
contiguity with each other brings up the smaller projections 
idimensions of the yr, and the symmetry of the cells is re- 
4 In Closterium (fig. 387 ; Plate Tk, fg. 2) the two halves of 
Wochrome first retreat from one another at the sutural line, and 
friction takes place round the cellulose wall : this constriction 





amore elongated and contracted shape. Thus, in five or six 
after the le el sep ae ey Cee ee 
and each resembles the cell by the division of which it originated. 

The process is seen to be after nearly the same method 


neck ; and they progressively increase until they assume the appear- 
ance of the half-segments of the popes cell. In this state, there- 
fore, the plant consists of a row of four 

the two old ones forming the extremes, and the two new ones (which 
do not usually acquire the full size or the characteristic ings of 
the original before the division occurs) occupying the int i 
place. At last the central fission becomes complete, and two bi- 
partite fronds are formed, each having one old and one young seg- 
ment ; the young segment, however, soon acquires the full size and 
characteristic aspect: of the old one ; and the same process, the 
whole of which may take place within twenty-four hours, is repeated 
ere long. ‘The same general plan is followed in Micrasterias den- 
ticulata ; but_ as the small hyaline hemisphere, pat forth in the 
first instance from each half-cell (fig. 388, ‘Aj, enlarges with the flow- 
ing in of the endochrome, it undergoes progressive subdivision at its 
edges, first into three lobes (B), then into five (C), thon into seven (D), 
then into thirteen (E), and finally at the time of its (FY 
acquires the characteristic notched outline of its type, being only 
distinguishable from the older half by its smaller size. The whole 
of this process may take place within three hours and a half, In 
Spherozorma the cells thus produced remain connected in rows 
within a gelatinous sheath, like those of Desmidium (fig. 391); 
and different stages of the process may commonly be ol in 
the different parts of any one of the filaments thus formed. Tn any 








DESMIDIACER 513 


it is obvious that the two oldest segments are found 
extremities, and that each subdivision of the inter- 
must carry them farther and farther from each other. 
different: mode of increase from that of the Confervacec, 
monly the terminal cell alone undergoes subdivision, 
n ye one at formed i ia bade 
generative in the Desmidiacee, which occurs 
compared to that of binary division, always consists of 
eonjugation.’ It commences with the dehiscence of the 


Ss 
Ba—Soccessive stages of binary subdivision of Micrasterias denticulata. 
r 


envelope of each of the conjugating cells, so as to 
t it into two valves (fig. 389, C, D; fig. 390, C). The 
of each cell thus set free without any distinct investment 
those of the other ; and a ‘ zygospore’ is formed hy their 
soon acquires a truly cellulose envelope.' This enve- 
first. very delicate, and is filled with green and granular 
af by degrees the envelope acquires increased thickness, and 
btents become brown or red. Ultimately the envelope be- 
wdifferentiated into three layers, of which the innermost and 
wast are colourless, while the middle one is firmer and brown. 
exrtain species of Closterium, as in many of the Diafomacea, the act of 
fiom gives origin to two sygospores. bi 





514 MICROSCOPIC FORMS OF VEGETABLE LIFE 


‘The outer surface is sometimes smooth, asin Closterinm and its allies 
i hat ene alan aon 389, 

D; Plate V! 4), the spines 
ding ence ea on 


45° 
EE 
ag 
qj 
i 
3B 





y 
[ 3 
ih 

z 

H 


the cavities of 
391, D, E) this tube 


a Cecingall inm entire rome of one cell passes 
bh ohare: matte ean ee over into the cavity of the other 


ccll-envelope; C, transverse view: (D); and the two ans ‘led 
asics lhe el agar? pa to form a single mass es as 
is the case in many of the 

gate, The joint which contains the zy; can scarcely be 
distinguished at first (after the separation of the empty cell), save 
hy the greater density of its contents ; but the proper coats of the 


Cosmarinm botrytis. After 
Teoma at rest fora con- 
siderable time, it i- 
nates by the Darian 
the two outer coats, the 
protoplasmic contents es- 
eaping while still enclosed 
in the innermost coat. In 
a : this body the 
990. —C of Closteriuen striotatumn : 
FE a ee ee al 
conjugation, with zygospore. nahieh, Sonkicelieaniehiens 
and the whole becomes enveloped in a new eell-wall. A constric- 
tion has, in the meantime, made its appearance between the two 
halves, which are of somewhat unequal size, and thus the new 
desmid is formed. 











scoop. Other species form a slimy stratum floating surface of 
Doric c= or dirty cloud upon the stems and leaves of 

aquatic ; and these also are best detached by passing 
the hand beneath ge teal aa Sep between the 
fingers, so as to Go ertinvems to it, Tf, on the 
other hand, the of we are in search should be much 


sink to the bottom, and most of the may then be poured 


water off, 
to be replaced by a fresh supply. If the bottles be freely to 
solar light, these little plants will flourish, apparently ax asin 
their native pools ; their various phases of and 
reproduction may be observed during successive months or even 
years. If the be too deep for the use of the hand and the 
scoop, a collecting-bottle attached to a stick may be employed in 


its stead. The ring-net may also be ad 

especially S#4¢ bathe constenetea Tal to lle ee e be rhe 
several 
umber 


S¢ 


tion of one piece of muslin for another. For, by 
pieces of previously wetted muslin in era yr le n 
of these minute organisms may be a water ; 
pars of muslin may be brought folded up in wide- 
mouthed bottles, either spunialy or several mba | according as 
the organisins are obtained from one or from several waters ; and 
they are then to be opened out in jars of filtered river-water and 
“Pie Diatomatte like the, Deomidince, nr simple ely 
iatomacese, like the di are ai 
a firm, external coating, within which is included an regimen. 
whose superficial layer constitutes a ae utricle,’ but their 
external cont is consolidated by si/ex, the presence of which is one 
of the most distinctive characters of the group, and gives rise to the 
liar surface-markings of its members, It has been 

yy some that the solidifying mineral forms a distinct layer 
from the exterior of the cellulose wall ; but thore seems good reason 
for zseaciioa that wall as itself interpenctrated by the silex, since 
® membrane bearing the characteristic surface-markings is found to 





je 





eager M rio (tig. 
ate mg a and i * 
Fo concede boners 


Sees, tse, 
ponent Life Mooatagterpr . | sometimes con- 
Sth calle chi the Polnallacos diatoms, have, 





for —e with Tceretiun( 3 Siem iia ra 
1), Campylodiscus (tig. a  Coscine- 
(Bw ty Cora 5,4), Aetoplt, aod many poe 
i forms, however, when obtained living state, are 
commonly found cohering to the surface aes ts, 

We have now to examine more minutely into the curious struc- 
ture of the silicitied casing which encloses every diatom-cell or 
Froesins and the ee which imparts a Spates interest to 

MP 5 fa calif tut alas treogh tbe ped cation’ ofthe 
it often exhibits, but through the perpetuation 
ingtoee details of that pattern in the specimens 
fossilised deposits. This silicified casing i caaallp fobsadl of ff two 
perfectly 5 7ametzical valves tnited talon aomtbeGiky mit oEieO 
asta ee rings which constitute the connecting zone or girdle, aml 
thus exactly represent a minute box which serves for the Be 
tion of thespecies. This process is known as the encystment, and 
not uncommon, especially amongst the Wavieu/acen, frustules paced 

frequently found amongst them open from the separation of 
valves, showing the two rings covering each other, as the eae 
box may cover a portion of the box itself, 

It isthus not correct to designate the line shown in the front view 
of the outer ring as the line of ‘suture,’ since the sutwre is the line 
of meeting bounding two surfaces placed on the same plane. The 
form peti, however, varies widely in different diatoms 5 for 


ii 
if 


u 


sometimes each valve is hemispherical, so that the cavity is globular ; 

sometimes it is a smaller segment of a sphere pa 

glass, so that the cavity is lenticular ; ecuvetinnas te the conteal 

is completely flattened and the sides abruptly tu the 
beats resembles the cover of a pill-box, in w! iene ease = 


be cylindrical ; and these and other varieties mn ao-axietiw 
modifications of the contour of the valves, which ta aes re eee 
triangular (fig. 393), heart-shaped (tig. 405, A), boat res ee 
A),or very much elongated (fig. 100), and may be fi 





520 MICROSCOPIC FORMS OF VEGETABLE LIFE 


although it may be very minute ; while Vawicu/a has been sometimes 
seen with the valves actually separated, 





Fio. 392.—Maguifleation of ‘ultimate wtrno- 4 

Tr’ of Conesntzevaagteromphal tena lute adhesion to any aos 
fenurs, Nelson an a 

CQoakett Sournal" vol. ih ser. p. held by some students of diatom 


of unrivalled manipulative skill to be the absolute structure of some 
of the larger forms. 

Thus concerning the group Coscinodiacee, the most, 
beautiful of the discoid forms of the whole group of Diatomacee, we re~ 





Fio. 898.—Triceratinm faous: A, side view ; B, front view. 


present in fig, 3, Plate I, a micro-photographie i of C. axterom= 
phalus magnified 110 diameters, But in fig. 392 the areola of this 
diatom are seen under great magnification with recent powers. It 
is contended that the diatom, although consisting of asingle siliceous 
membrane, has a double structure, viz. coarse and fine 

the latter within the former ; and there appears little reason to doubt 
this, The coarse areolations are for the most part circular in outline, 
and the intervening silex is thick. Inside these areolations is an ex- 
tremely delicate perforated membrane, the outer row of whose: 
tionsare larger thantherest. Fromthevery delicacy of thismembrane, 
and its consequent easy fracture, it is often wanting, In Plate I, fig. 
4 we present a photo-micrograph of the same object magnified 2,000 

iameters. 









Pleurosigma angulatum. 

Magniflod 4900 diams. 
From a Phote-Micrograph by Dr. R. Zeiss taken 
With the 2 am/fm. Apochromatic Objective N. A, \.30 
a and projection eye-piece 4, 


Ae Baht & Co, Frankfort on the Mate 





























528 MICROSCOPIC FORMS OF VEGETABLE LIVE 
point, ot iy i ro disposed to accord our preference to that 


curious by d piste. 
a eee 
ously in the animal kingdom, although it affords no evidence of con- 


direction, before they letached—-is found to be in general » 
movement backwards and forwards in a straight line so far as they 
meet with no impediment, while the intervention of obstacles 
determines passive change of direction. The cause of this move- 
ment is uncertain ; but the most probable interpretation attributes 
it to the action of the changes resulting from nutrition of the 
cell, which must necessarily absorb food in a liquid condition. 
Taking account therefore of the relatively of quantity of 
silex necessary to the organisation of the diatom nm 
to its minute dimensions, and bearing in mind, at the same 
the incalculably small traces of silex in solution in the water, it 
may be understood how active must be the eset from the 
exterior to the interior of the cell, and vice versa, and hence how 
such an exchange must determine a continual change of position 
backwards and forwards, through the reaction exercised on the 
oe floating eee a 

Conjugation, so far as is at present known, takes among 
the adbarr Diatomacee almost exactly as a the Bas, 
except that it sometimes results in the production of two * 
spores” instead of a single one, Thus in Swrirellce (tig. 404) the 
valves of two free and adjacent frustules separate from each other, 
and the two endochromes (probably included in their primordial 
utricles) are discharged ; these coalesce to form a single mass, 
which becomes enclosed in a gelatinous envelope ; and in due time 

1 “astracang, ‘ Olwervationson the Genera Homeceludia and Schizonema,! 
Atti dele deca, Pontif. dei Nuovi ince, May 21 1580 = im 


, 


f 











val 

= "this formation of. hat termed ‘ auxospores'—as serving to 
wi 

scgzent he son of the cls which ar to origin to a new 


ees, Seen Soca rath 


inequalit ees 

same sl the hare Beanery ate 

aera mer or a 
are the products of a kind of conjugation 


of the ordin noe ariel gir ter 
Shaaeeparation: He describes 0  eudoshroee, oF iparticalan fras- 





Fro. 898.—Selt- tion (2) of Melosire italien (Aulacosira evenulata, 
‘Thwnites); 1, sim] je flament; 2, filament developing peer ener ome 
‘sive stages in the formation ef auxospores; anxospore-frustules in successive 
stager, a, 0, ¢ of multipliontion, 


tules, after separating as if for the See of a Perse se new cells, 
aa moving back from the extremities towards red 
increasing in quantity and aggregating in ago eae 
a, b,c); around this a new envelope is 
may not resemble that of the ordinary pelea but which peted 
in continuity with them ; and this zygospore soon. 
aubdivision (No. 3, a, be), the colls of te pl series thus me 
presenting the character of those of mt 
greatly exceeding them in size. From what has been already stated, 
it seems probable that a al reversion to the amaller form takes 
place in Seated subdivisions, a further reduction being checked 
1 i Prof. W. Smith ‘Ou the Determination 
of pelos ta the Distemasont ie Tie" Quart fon of Mierooe. vel bi. 
1829, p, 1004, a memoir by Prof. W. Gi ny *On Shape 
Character of Diatomacee,’ in Trans, of Microsc. Soc. 2ud series, vol. fii. 1855, 
aes 9 the Author's Presidential in the same MO; 
la crassinervis, Frustwlia saonica and N, rhomboides, 
Wi De Dallinger, Month(y. Mécro, Journ. 1876, wol. xvii. p. 1; also 
on the identity of these, by the same Author, sbid. p. 17% 





— 








i that many of the forms at present: asdis- 
resign pre prove to be but different states 
same, if their whole were i other hand, 
it is by no means that some which to be nearly 
Se tiiarieare: be ive Walenliauen Reamiend oes 
may: veg 5 
present, therefore, ony clasaieation rust bo merely proviaional 


and in the notice now to be taken of some of the most: 
forms of the Diatomacee, the method of Professor Kiitzing, 





Fig. aon, 
Fra. 890.—Meridion cirentare. Fi0, 400.—Bacillaria paradora, 


is based upon the characters of the individual frustules, is followed, 
in SraAleecien to that of Mr. W. Smith, which was founded on 
the degree of connection remaining between the several frastules 
after binary division.? Tn each family the frastules may exist under 
four conditions : («) free, the binary division being entire, so that the 
frustules separate as soon as the process has been completed ; (b) 
stipitate, the frustules being implanted upon a common stem (fig. 
401), which keeps them in mutual connection after they have them- 
selves undergone a complete binary division ; (c) united ina filament, 
Navitala brie fon, by the encoun taco of ta aha eRgnse REEL 
bodies, which, like gemninles, give rise to Surirella microcora. These by comics 
tion producn N. gplendia, which gives tive to. bifrons by the sataa o 
only able to speak positively, howover, as to the production. bf ran apne 
dida; that ot Surirella microcora trom XN. bifroms, and that N. splendid 
Surirella microcors. being matters of inference from the phenomena wil ‘ius, 

? The inethod of Kilteing was the one followed, with some by Mr Ralf 
in his revision of the group for the fourth edition of Brichard’s Dafaeoria: and 
to his aystematio urrangement the Author would refer such as desire more detailed 
information. 








“DIATOMACEA!: EUNOTIEA, MERIDIEAD 533 
which will be continuous “aie eecre corer 


‘gi a 10) nn ‘oheion be lamited od 


the g ia the frustules are free ; in ia they are very 
Steal arent yt tat o concn tae of the panei 
zone ; and in Himantidium they are usually united into ribbon-like 


" In the family Meridien we find a similar union of the 
striated individual frustules ; but these are narrower 

sat one end ‘at the other, 
so a8 to have a cuneate or 





it its itwelf . 
a su ead peetiacin as 

in teat tered Fro. 401.—Léemophora flabellata. 
ed States, the bottoms of which, to Professor Bailey, 
‘covered in ca aan spring with « ferru- 
shah ara Hegrgl about a quarter ect an inch thick, 
adhered proves to be filled with 
relies ‘of twig, spa ly beautiful siliceous bodies. 
of — Are hones ors d 

wavit a filamentous 
ee i See asta tat 
itinous cushion ; but this disappears 
Reith Sci Liomiphores also tha fraalae 
























ot 


i 


2 
a 


i 
E 
(2 


ies 
eae 


Vie yon: Pe een Diatoma, which gives ite 
Fro. 402—Diatoma vulgare: a, site view of TAC ; 
pftilag hs frntae wiergcing division.” © rer name icone means 
‘10. 40, ummatophora: a, fron! through) sug 
‘nd side views of single fruatle; 6, by front and Seated by SuuScH 
end views of dirided frostale; « frastale abont Beste 
to ndergo division; d,frustule completely 


along their lines of junction, but remain connected tae 
80 as to form zi; chains (fig. 402), The valves of Dintoma, 

turned sideways (a), are seen to be strongly marked by transverse: 
strie, which extend into the front view. The between 
the length and the breadth of each valve is found to vary so con- 
siderably that, if the extreme forms only were there 
would seem adequate ground for regarding them as jing to 
different species. The genus inhabits fresh water, preferring gently 
running streams, in which it is sometimes very abundant. The 
genus Frngilaria is nearly allied to Diatoma, the difference 








broader and others narrower than S. evnatriota; the 
See Tiedt thea aye ainbinti acta eeeateeee 
nee few are marine ; and several occur in those infusorial 
PE ROTA OR Ter mapa OTR eT earn 
such as that of the Mourne Mountains in Ix b, 6, ke 
Tn the genus Casspatodieene (Se a08) he eel eee yi 
ceeened in breadth ‘present almost: the form of discs (A), 
at the same ; twist or saddle- 

* are most developed, and it i i 

be best st ing here interoally 
projectii examination 
: ee 
eon smere 
ipso ‘in fresh water; a « 
beautiful form, abundance in the 


Fria. 405. —Campylodiseus costatua: A, front view; B, side view. 


infusorial stratum discovered by Professor Ehrenberg at Soos, 
Ezer, in Bohemia, that the earth seems almost entirely composed 
The next family, Striatellec, forms a distinet group, 
entiated from every other by having Tongdeudinal cost on 
connecting portions of the frustules, these coste i A 
the inward projection of annular siliceous plates (wl 
however, reach to the centre), so as to form septa dit the 
of the cell into imperfectly separated chambers. Tn some 
these annular septa are only formed during the production of 
valves in the act of division, and on each repetition of such 
duction, being thus always definite in number; whilst in 
‘cases the formation of the septa is continued after the 
of the valves, and is repeated an uncertain number of times before 
the recurrence of a new valve-production, so that the annuli are 
indefinite in number. In the curious Gram 
(fig. 403) the septa have several undulations and incurved ends, 80 
as to form serpentine curves, the number of which seems to vary with 
the length of the frustule. The lateral surfaces of the valves in 


full 





ad ( emeaning of the remar! 
difference in the sizes an the frustules of the same 
filaments (fig. ees ity seal The sides of 
‘the valves are marked with radiating strim (fig. 419, d, d) ; 
and in some speci have toothed or serrated margins, by which 
the frustales er. ‘To this family belongs the genus Hyalo~ 
discus, of which H. subtilis was first brought into notice by the 
late Professor Bailey asa test-object, its dise being marked, like the 
with lines of exceeding delicacy, 


asa 
ngine-turned back of a watch, 
+ visible by DE iced and careful illumination. 
- family inodtisceer includes a large Brogartion of the most 
c considerable convexity, and are connected by a narrow 
‘The genus Coscinodiseus, which is easily distinguished from 


of the genera of this family by not having its dise divided into 
a is of great iteheat tor the rae abundance of its 


* 
é. 
25 
s 
s 
Gas: 


538 ‘MICROSCOPIC FORMS OF VEGETABLE LIFE 


valves in certain fossil Lee hee pecially the 
as also in guano. Ench frustule is of discoidal shape, being com- 
posed of two delicately valves united bya ee 








Fis, 406—8 of siliceous valve of Coscinoiisous coulus ériitis: 1, Lexagomal 
peat creer nol reesra em ym) 
Professor J. Quekett in connection with hytes which had beew 
brought home from Melville Island by Sir E. ; and the species 
seem to be identical with those of the Richmond earth, ie 
investigations of Mr. J. W. Stephenson ' on Coscinodiseus ocnlus 
iridis show that the peculiar ‘eye-like * appearance in the centre of 
each of its hexagonal areolw arises from the int of the 
vegeee of two distinct layers, differing considerably in structure, 
the markings of the lower layer being parially ome through those 
of the upper. By fracturing these diatoms Mr. Stephenson 
ceeded in rating portions of the two layers, so that 
be peareast saa He also mounted them in Bisulplies of 
carbon, the refractive index of which is high; and in w 
solution of phosphorus in bisulphide of carbon, which has a still 
higher refractive index, If we suppose a diatom to be marked with 
convex dey ons, they would act as concave lenses in air, which 
is less refractive than their own silex ; but when such lenses are 
immersed in Iphide of carbon, or in the phosphorus solution, 
the more refractive: 


J 
hi 





they would be converted into convex lensas of 
substance, and have their action in air reversed. Analogous hut 


1 Monthly Microscopical Jowrnal, vol. x, 1873, p. 1. 





by the hexagons of the cyper sper te 


= 
= 


i 
if 
[ 
= 
i 
7. 


ERLE 
Bh 
FI 
ie 


5 
l 
1H 
Ht 
iy 


it is evident that such minute di ween 01 
wise similar are not account to serve for the separation of 
species. This form is very common in Techaboe. Allied 








sometimes specially continuous with the umbilicus. 
ee atte Bevel oe Soa 
her generic designation, Spatangidium ; but it may 
whether this is founded on a valid distinction.” These 
Author concurs with Mr. Ralfs in thinking it preferable to limit the ganux 
st dh forma riginlly chad it Hhhrenbeng, and to eestore the 
E nbeg which had been properly united with Actino- 
pin Quart. Journ. Microsc. Science, vol. vii. 1889, } anil | 
EN a a Oa tng 
the sane Tronarctions, vol. viii, AND, p. 44. 


La 

















| 


The 
Fin. 407,—Actinopt; tindulatea: their living state appear to 


A, side view; B, front view, 
‘or zoophytes. 
The Bermuda earth also contains the very beautiful form 
which, though scarcely separable from oe the die 


i 


its marginal spines, has received from Professor 
tinctive appeliation of 4eliopelta (sun-shield). The object is repre- 
sented as seen on its internal by the parabolic illuminator, 
which brings into view certain features that can scarcely be seen by 
ordinary transmitted light. Five of the radial divisions are seen to be 
marked out into circular areolw ; butin the five which alternate with 
thema minute beaded structure is observable. ‘This may be shown, 
by careful adjustment of the focus, to exist over the whole interior of 
valve, Clee a umee in which Reger areolation is 
hore displayed ; and it hence appears probal is marking 
belongs to the chicaallasent ecH that the circular areolation 
‘exists in the outer layer of silicified valves. In the alternating 
divisions whose surface is here pease the areolation of the outer 
layer, when brought into view ssing down to it, is seen to 
be formed by equilateral triangles; it is not, > nearly 80 
well marked as the circular areolation of the first-mentioned 
divisions. The dark spots seen at the end of the rays, like the 
It iw stated by Mr. Stodder (Quart. Journ. Microsc. Science, yol. tii, me 

1863, p. 215) that not only has he seen, in Urok 
sien ting beyond the onter, but that ho. has Heo ene ty opto 


Feparated from the outer. ‘The Author is indebted to thi gentleman for 
‘out that his figure reprosenta the inner surface of the valve, 





: 
i 
é 
A 
i 
i 


Es 
1 
& 
fs 
aa 
Wp 
# 
ce 
1 


ie 
aty 
ases 
aeet 
BaF 
ine 
BEEF 
eEes 
Z 
ees 
as 
EEE: 


1 


character of their discoid frustules, and with the Bid- 

ie epee ereeen Caccees Bit cele satel virions Tn 

the iful Aulacodiacus reolations are situated near the- 
tr and are connected with bands radiating from the centre ; the 
also is frequently inflated in © manner that reminds us of 

a ‘These forms are for the most part obtained from 


“The members af the next family, Biddulphiew, difier greatly in 
their general form from the preceding, being remarkable for 
the. it of the lateral cate! which, instead of being 

flat or idal, so as only to. present a thin ein front 
, Are 80 convex or inflated as always to enter largely into the 
view, causing the central zone to appear like a hand between 


Bu 


1 Society, Unt warios, vol iii. p. 49. < 
waite aed ‘mh for showing the ‘convereon of rliet” in 


able ta 
imerncope (99) 





3 
| 
F 
i 


= 





Fro, 0R—Iethmia nervosa, existing ocean and of tidal rivers. The 
7. favua (fig. 393), which is one of the 
Jargest and most larly marked of any of these, occurs in the mud 
of the Thames and in various other estuaries on our own coast ; it 
has been found, also, on the surface of Jarge sea-shells from various 
parts of the world, such as those of ippopus and Haliotis, before 
they have been cleaned ; and it presents itself likewise in the infu- 
sorial earth of Petersburg (U.8.A.). The projections at the angles 
which are shown in that species are prolonged in some other species 
into‘ horns’ ; whilst in others, agnin, they are mere tubercular eleva- 
tions, Although the triangular form of the frustule, when looked at 
sideways, is that which is charncteristic of the genus, yet in some of 
the species there seems a tendency to produce ar and. 
pentagonal forms, these being murked ax varieties by their exact 
correspondence in sculpture, colour, &c, with the normal triangular 








cate, 


sion. 


or altogether wanting on one of the valves, which is distinguished 
as Nhe iatarice, ‘This family consists but of a single genus, Corconeis, 
which includes, however, a great number of some or other of 
them tee) in every part of the globe. Their form is 
that of ellipsoidal dises, with surfaces more or less 
plane, or slightly curved ; and they are very commonly: adherent 
to each other. The frustules in this genus are frequently invested 
membranous enyelope which forms a border to them ; but 

1 800 in . Journ, Microsc, iv. i 
vat Sr Sct Gert, are, lo lines a 
and West, in » p 151, 





a 


DIATOMACER: ACHNANTHEA, GOMPHONEMEE 545, 
Se eee to the immature state, subsequently disappearing 


more or less: 
Another family in which there is a disimiarity in the 


(as in Yavicula), the lower valve (a) has also a transverse line, form~ 
Sp marae poem mith, wanting io the valve (¢). A 
Easton ween he mae orm an al 


n fig, 412 it not 
together the 

from the subdivi- 

of the lowest cell, a, 
which are not com- 
ely se] the one 
the other, but it may 

be observed to invest the 
twofrustules) and ¢, which 


Paap mes aiteret el a 2 
Si ad Peal 414-—domphonenta og Seer Net 


gheeong ia Phuary eat: Gy Bronate i te aot ot lita 
it 


may 
i preieloiavs thers fm wish he rsa ing 
ieerarnen See. pasiare completly, Erved itself. 
the fami) Cymbatos, on the other and. both valves 
the Insgitorlinal tne ee aie the middle of its length ; but 
Savio karsibe of those of the Zunotiee, and the 
Beet aikcer cue nnegin tho te coir tthe nodule 


4 
(6, ese, like the Meridiew and Liemophorea, have 
ttle which ar cn cuneate or wedge-shaped in their front view (figs, 


413, 414), but are ‘ished from those forms by the presence of 
the oe ae nodule. Although there are some 
‘free 


i 
HI 


| 
5 
FE 
3 


i 
ie 
i 





pony the greater part of them, included in the 
have their ules either affixed at their bases 

toastipe. This stipe seems to be formed by an exu- 

at a the frustule, which is secreted only during the process 


dation 
‘of binary division ; hence, when this process has been completed, the 
nsion of thesinglo filament below the frustules ceases ; but when 
NN 








of which are disti the of their frustules, as 
See re mace Sete tue Monae by the pree of « 
median longitudinal line and central nodule in both valves. In the 
genus Navicula and its allies the frustules are free or simply 
adherent to each other ; while in another large section they are in- 
cluded within a gelatinous envelope, or are enclosed in a defi- 
nite tubular or gelatinous frond. Of the genus Naviewla an 
iariguias csatobde GF cia va V eee pect eS of 
separation often extremely trivial. Thase have o 
datered sae curvature dare ee pipe Ki 
under wi ch now | ; 
but, Bie Sato oes a 


Taric had been i 
ide Cir species), ee “ gtr ee 


i 
i 
FF 


. Ralfs, 
because in muany of th sunea tatatalepesiar te to teats to 
dis ‘ish with certainty between stri and cost. Mr. Slack has 


2 
a 
£ 
i 
a 
e 
4 
5 
3 
z 
: 
a 


twelve species of Pinnularie into‘ beaded *structures.' The beauti- 
ful Stawroneis, which belongs to the same differs from 
all Nepaedive forms in having the central le of each valve 
<lilated laterally into a band free from strie, which forms a cross 
with the longitudinal band. The multitudinous of the genus 
Navicule are for the most part inhabitants of water ; ae! 
constitute a large part of most of the so-called ‘infusorial earths’ wl 
were deposited at the bottoms of lakes. Among the most remarkable 
of such deposits are the substances largely used in the arts for the 
polishing of metals, under the names of Tripoli and rotten-stone; these 
consist in great part of the frustules of Vavicule and Pinnularie. 
The Polierschiefer, or apres slate,’ of Bilin in Bohemia, the 
powder of which is largely used in Germany for the same 
and which also furnishes the fine sand used for the most 
castings in iron, occurs in a series of beds avs ‘ing fourteen feet in 
thickness, and these present a) noes wl indicate that enh 
nave been at some time ex to a high temperature. The 
known ‘Turkey-stone,’ 80 generally employed be the of 
tools, seems to be essentially composed of a similar 
of frustules of Waviculw é&c. which have been consoli by heat. 
The species of Plewrosigma, on the other hand, are for the most part 
either marine or are inhabitants of brackish water, and they compara- 
tively seldom present themselves in a fossilised state. Of Stauronew 
some species inhabit fresh water, while others are marine ; and the 
former present themselves frequently in certain ‘infusorial earths.” 
4 Monthly Microscopical Journal, vol. vic 1871, p. TL. 


DIATOMACEH:: SCHIZONEME 547. 
the members of the sub-family Schizonemew, consisting of 
‘those Navicule in which the frustules are united by a gelatinous 
remarkable for the great 
eS This is ‘ially the case with 
the | the gelatinous envelope forms a 
a 


hdd Feo poet into the of the frus- 
tule, each frustule is ich aM srg 
(fg. 416, B), which may any ital oe ther borne on a branching stipe 








—Schisonema Greil: natura soo; B, poston magni Ave 
Sey Secaplosss G. Shament tonpnitied 200 dasnetes op Mingle frestala, 


or peer Te ae ieee others into an indefinite mass (fig. 

wy te rere of these composite forms is a matter of 
eer cinco it enables us to bring into comparison with 

each | run nambers of frustules which have unquestionably 
‘4 common and which must therefore be accounted as of the 
same 5 ‘iad thus to obtain an idea of the range of variation 
in this group, without a know! of which specific detini- 

unsafe, Of the very strongly marked wiintinl whieh 

oceur within the mete aie single species, we have an example 
Sp ea E, F (6 416), which would scarcely have been 

same specific type did they not occur 

the careful study of these varieties in every 

sae no disposition to variation shows itself, so 

aN 2 


ae 











ALL 


io. sit—Mestoplote, Belthit: i a 
envelope; C-F, of ‘frustal 
H, frustule ikea ‘sabstrision. 

Fro. 417.—Mastoglota lanceolata. 





5 By frustole in ite 
pep Note tara 


of variation is far greater than had been previously it = 
and this tt expecially likely toe. the cage with such, ible 
organisms as those we have been considering, sinee they are: 

more influenced than those of higher types by the conditions under 
which they are developed ; whilst, from the very wide 

range through which the same forms are diffused, they are subject 
to very great diversities of such conditions, 

The general habits of this most in group cannot be 
better stated than in the words of tte Smith :-—* The 
Diatomaceer inhabit the sea o fresh water; but the species 
to the one are never found in a living state in the other locality ; 


= 


DISTRIBUTION OF DIATOMS ‘349 

“though there are some which medium of a mixed: and 
a Bee one or less brackish. » Tiara 

Sonat ieee 
a8 
ofthe tn rn of rivers, where, on Are Petia of | 
of the water is Pepe Stasis: 
or more directly by the overtiow of its 
ee Other favourite habitats of the Diatomacee are stones of 





c 120 miles broad, was found 
pestle omar atrny the fants of Vittdsia Land 


would account for the presence of Diatomacee in Bae 
and pumice which was discovered by Professor Ehrenberg, Te is 
remasced inmate gl D. Hooker that the universal presence of this 
ition throughout the South Polar Ocean is a most 
i importa far Pee there is a marked deficiency in this 
vegetation ; and were it not for them, there 
or fo food Pete aes coe animals, nor (if it were possible 
themselves by preying on one another) could 
rates be be purified of the carbonic acid which animal re- 
ation and ition would be continually imparting to them. 
i to ae oe ea ecies of sles tee soi 

every degree latitude between Spitzbergen 

wilt other sem nied to Peutelts nego PUe 
of the most ar instances of the preservation of pepe Be 
forms is their in guano, into Which they na have passed 
net lassen ‘canals of the birds of whose accumulated excre- 
‘ment ibstance is composed, those birds having received them, it 


550 MICROSCOPIC FORMS OF VEGETABLE LIFE 
is probable, from shell-fish, to which these minute organisms serve as 
ona food. 


‘The indestructible nature of the silicified casings of Diatomacee 
lias also served to perpetuate their ce in numerous localities 
from which their living forms have long since disappeared ; for the 
accumulation of sediment formed by their successive production and 
death, even on the bed of the ocean or on the bottoms of fresh- 
water lakes, gives rise to deposits which may attain considerable 
thickness, and which, by saberies changes of level, may come to- 
form part of the dry land. Thus very extensive siliceous strata, 
consisting almost entirely of marine Diafomacee, are found to alter- 





Fro. 418—Fossil Dintomacem &o. from Oran: a, a, @, Cosoinodiseus; b, bb, 
Actinocyclu Dictyochya fibula; d, Lithasteriseus radiatus; ¢, Spongolithis 
acicularis: f,f, Grammatophora parallela (side view); 9, 9, Grammatophora 
angulouc (troxit view). 





nate, in the neighbourhood of the Mediterranean, with calcareous 
strata chiefly formed of /oraminifera, the whole series being the re- 
presentative of the chalk formation of Northern Europe, in which 
the silex that was probably deposited at first in this form has ander- 
gone conversion into flint, by agencies hereafter to be considered. 
Of the diatomaceous composition of these strata we have a character- 
istic example in fig. 418, which represents the fossil Diatomacem of 
Oran in Algeria. The so-called ‘infusorial earth’ of Richmond in 
Virginia, as well as that of Bermuda, both marine deposits, are very 
celebrated among microscopists for the number and beauty of the 
forms they have yielded ; the former constitutes a stratum of eighteon 
feet in thickness, underlying the whole city, and extending over an 
area whose limits are not known, Severe! dates of more limited 















RS / iF 
position th Teac dabei naps ie oa a eld in 
mixed with mi reign matter ; this may be partly got rid of by 


oe _ oo 
mod 





‘the digestive ca y us 
that may fall in his way, gi ae tepe.ercmg 
obtained from the interior of Joetilwea. The separation of the 
diatoms from the other contents of these stomachs must be accom- 
lished by the same process 
From geste or the satrareors clipaaral arty Of mates es yaa 
ing are the most essent H 4 or is 
to be washed several iota iaipie pelt hs should be well 
stirred, and the sediment then allowed to subside for 
before the water is poured off, since, if it be decanted too soon, it 
may carry the lighter forms away with it. Some kinds of earth 
. have so little impurity that one washing suffices ; but in any case 
is to be continued so long as the water remains 
‘it is then to be treated, in a flask or test-tube, with 
loric (muriatic) acid, and, after the first effervescence is 
gentle heat may be applied. As soon as the action has 
time has been given for the sediment to subside, the acid i 
poured off and another portion added ; and this should be 
as often as any effect is produced. When hydrochloric 
to act, strong nitric acid should be substituted ; and 
effervescence is over, a continued heat of about 200° F, 
‘applied for some hours. When sufficient time has been gi 
subsidence, the acid may be poured off and the sediment treat 
another portion ; and this ix to be repeated until no farther acti 
takes place, Tho sediment is then to be washed until all 
the acid is removed ; and, if there have been no admixture of siliceous 


E 
: 
3 


[ 
gltyt 


E 


2h 
ile 


So 


“COLLECTION AND MOUNTING OF DIATOMS 


fern iishaneclorbaln tered this sediment will cn ia 
Spsemneet aces nt ‘anithe lds Reision oft ate gre 


«till in motion, oif the si ts soon, 
a I eaetied's this sic 
and this process te repnt th four ti e 
+ ma) ree or nes at 
i tno fre sine subsides after the 
bongs embed with, a "a ray ons ey 
vi "i 5 ‘ps, some iat 
which 1 out from ami them dl the it 
+ Ee A ese eataaly: ob intent, ee 
v graduated that the earliest sediments may be 
while the Intest will th "High powers a a ae 
— an wi 
require the reves oes oan tat 


iu 
Hi 


deposit: Doiled for a short time ina weak 
solution, which will act upon this cement more readily than 

ala ae lay es ; and as soon as the lump is softened, so as to 

crumble to Bee is must be immediatel ly washed in a large quai “ip 


Eselteabes! (and chan treated in tho “use! way. meee 
solution dons not answer the purpose, 0 sto 
en be tried. This method, devised by 
practised by with much success in various cases,” 
‘The mode of mounting specimens of Diatomacer will depend 
the they are intended to serve. If they can be 
iained fresh, and if it be desired should exhibit, ax 


as the presented by the livi ants, 
cont in anes media wi within oe cates bat ce 
within & short time after they tive ised 
about a tenth of alcohol should be added to the water. 
‘be desired to exhibit the stipitate forms in their natural position 
a ladiaen other: Reeene ants, the entire mass may be mounted 


jell; a Le a deeper cell ; and such a 
i aonliriey a ey orn er ‘f the beck: -ground illumina- 


‘Ti, on the other hand, the pairs structure of the siliceous 
is the feature to be brought into view, the fresh diatoms 
pebed hee (eaten in nitric or hydrochloric acid, which must then be 
(sufficient time being allowed for the deposit of the 


ae 


i. Ne is described 

ae ‘in the Geert Journal uel Sere Seer ee aes Tae. 

Author believes, however, above described will answer every 
methods of diatoms, see Quart. Journ. 

eee od ohh sel, p. Th and rans. of 

book entitled Practical Directions 


‘anid Mounting Diatoms (New 
fohnwon, 


Seager te ie ed a per 


= 





residue) ; and the sediment, after should be boiled in 
water ia sl of A ’ ; cleansed 
from matter wl % ‘retain,’ 
After u further washing in water, are to be either mounted 
in balsam in. manner, or be set up ‘dry’ on a very thin 
slide. In order to obtain a t markings, objec- 
tives of very large aperture are and all the improvements 


ished under a simple microscope may be taken 
hair pencil which jepson so. TinnLon to leave two: 
prclecting youd the rest. But the smaller can only 
y a single bristle or stout sable-hair, which We: be inserted 
into the cleft end of a slender wooden handle ; and 
hair should be split at its extremity in a brush-like manner it will 
be particularly useful. (Such split’ hairs may always be found in a 
shaving brush which has been for some time in use ; those should be 
sel which have their split ions so closely in contact that 
they appear single until touched at their ends.) When the 
extremity of such a hair touches the glass slide, its parts separate 
from each other to an teparilgy seacerircg 
Bela brought up to the object, “pushed to the edge of the fluid 
on the slide, may generally be made to seize it. A 
American diatomist, Professor Hamilton Sunith, recom- 
mends a thread of glass drawn out to capillary fineness ility, 
by which (he says) the most delicate diatom sort Ge Lasay Garo 
and deposited upon a slide damped by the breat For the selection 
and transference of diatoms un x the Som pon Ee ee 
may be had to some of the forms of * finger’ which have 
been devised by American diatomists.? 
@.—The greater number of the sea-weeds exhibit » 
higher type of organisation than any that has hitherto been i 
The old classification of sea-weeds into Melanosporem, Ri 
and Chlorospore, according as their ‘ing matter isolive- 
red, or green, cannot altogether be retail ‘Under the 
Pheosporee: is now included a very large number of the brown and 
‘ See Prof, H. I. Smith in Amer. Journ. of Microscopy, vol. 1800, R357. 


11 is important that the soap should be free fren silex, of any other 
matter. 
7 For a description of those of Prof. Hamilton Smith and Dr. Remner, see Journ 


af Roy, Microso, Soc. vol. ii, 1879, p. 961; and shat of Mr. Veeder, vol. ili, 184%, 
P. 700, of the same Journal. 


> 


tl 





#H 
83 
i 

ae 
eG 
4 
4 
& 
i 


closely resem) starch, and an olive-brown pigment, which tl 
share wit te Memon ne py ry a ee. 
soa-weeds presents us with lowest type in the family 
which, notwithstanding, some of the most 
OE ee to be found in the group, the 
eee ae ey be izeaecind by Mb . Such 
is the case, for example, wi ia, 2 small and delicate sea- 
which is very commonly found ing alge, either 
near mark or altogether submerged, its general form being 


the ends of which, however, have a decayed lool 

stem anes) Tin paren day poly cna nt 
r e) is apparent ibly cor in the 
resolution of Pedahnaae seth pemey cells into motile bi- 
ciliated which, when mature, escape by an i as with 
‘long tubular neck, which forms itself in the wall of the piesa 
‘The same with the terminal cells of the peculiar lateral 
branchlets, w! are known as tive buds. Janczewski, how- 
ever, believes that these so-called ant ids are really the zotispores 
of parasitic Fang eat to the family Chytridiacer, with which 
the S) lariacecs are liable to be infested. It is 

whether there is any true process of sexual reproduction in 


— 





556 MICROSCOPIC FORMS OF VEGETABLE LIFE 
Bh ee. ‘ Serusaee Pi me rat ne 
hepa et il the eats fe be bp io lang nr 


dein inte hairs, cae are divided reich oc “han 





of which gives birth to a single zotispore,. 
die cullsclar caer Wiecannen finely, 
while those from the maltilootlar wopctnas teaclase’ 4 


pairs before germinating. ‘The different families of My 
Secrit ated sistant geidoal i tere’ by mnie ste 
‘swarm-cells to the impregnation: aoe et ‘odsphere! anthe- 
Pe ee 
cular sporanges wi " to 
exactly alike, but « slight differentia- 
Sioa ealutted tn 





still further, and the female repractuc- 
2 tive bodies are true * olspheres, ae 
Seapine chelate ea 

in 


ing to the 
Fo. ce of pied tes an are included many of the 
Vinee “ee e — of the sea-weers, chiefly natives 
ing enormous dimensions, and exhibiting rudimentary differentiation 
into rhizoids or organs of attachment, stem, and leaves. Such are 
Lessonia, which grows toa great heightand resembles a branching tree 
‘with ae leaves two or three long ; Macrocystis, where the 
stalk- base of cach branch of the leaf is hollowed out into a large 
pear-shaped air-bladder ; Nereocystis, Laminaria, and others. 

Tn the Fucaces the generative on tus is contained in the 
globular ‘conceptacles,’ which are usually sunk in the tissue near the 
extremities of the fronds, In some ae as Fucus 
‘the same conceptacles contain both ‘antherids’ and ‘oigones "; in 
others these two sexual elements are disposed in different conceptacles 
on the same plant ; whilst in the commonest of all, F. vesienlosus 
der-wrack), they are limited to different individuals. When section 





558 MICROSCOPIC FORMS OF VEGETABLE LIFE 
0 that the ovspheres do not make their exit from the cavity until 
contents, which come into contact on their exterior, ‘The antheridial 





Fio, 422—Antherida and antheromids of Fucus 2 A, branching 
articulated hairs, detached from the walls of the antheride in 
different stages of deve it; B, antherozoids, some of free, others still 
included in their antheridial cells. \ 


tion, first a filament and then a frondose os a? is produced, which 
gradually evolves itself into the likeness of the parent plant, 

‘The whole of this process may be watched without difficulty by 
obtaining specimens of #, vesiculosus at the period at which the 
fractification is shown to be mature by the recent discharge of the 
contents of the conceptacles in little gelatinous masses outside their 
orifices ; for if ei olspheres wai have been pela) 
the olive-green conceptacles placed in a 
water in a oa ahalle cell, and a small quantity of the mass of 
antherozoids, set free from the orange-yellow (male) 
be mingled with the fluid, they will speedily be observed, the 
aid of a magnifying power of 200 or 250 diameters, to go 
the actions just described ; and the subsequent processes of 
nation may be watched by means of the ‘growing slide,’" The 

1 A shallow cell should be to pressure 
thie matte todos Beevuth; etisee Drovecnente ffl Slneine Repeat eae 


Fy 


FLORIDEZ 559 


from December to March, are the most favourable 

of these phenomena ; but where Fuci abound, 

will usually be found in fructification at almost 

of the year. This process of fertilisation usually takes 

exposed to the air on the wet beach between high- 

ieater mark ; and, to assist in it, the comparatively heavy 

hmany Fscacee are buoyed up by air-cavities, which take 

wf the well-known ‘bladders’ of the ‘ bladder-wrack ’ and 

fies of Fucus, imbedded in the frond, and the ‘berries’ of 

& baceiferum, the ‘ gulf-weed ’ of the Atlantic, which are 
im pedicels above the surface of the water. 

§ the Floridew, or red sea-weeds, also, we find various 

‘most beautiful forms, which connect this group with the 

2, especially with the family Chatophoracee ; such delicate 





Arrangemen: of tetraspores in Carpocaulon mediterrancum: A, entire 
{longitudinal vection of spore-bearing branch. (N.B.—Where only three 
‘ee are seen, it is merely because the fourth did not happen to be so pluced 
seen at the same view.) 


or leaf-like fronds belong for the most part to the family 
cee, some members of which are found upon every part of 
ts, attached either to rocks or stones or to larger alge, and 
mselves affording an attachment to zoiphytes and polyzoa. 
iefly live in deeper water than the other sea-weeds, and 
test tints are only exhibited when they grow under the 
Projecting rocks or of larger dark-coloured algwe. Hence, 
ing them artificially in aquaria, it is requisite to protect 
man excess of light, since otherwise they become unhealthy. 
species of the genera Ceramium, Grifithsia, Callithamnion, 





560. MICROSCOPIC FORMS OF VEGETABLE LIFE 





a ae multifidui: T, a branch with « earpogone, ¢, and Ie aed 


ap; U1, IIL, commencement of the formation of the fructification; IV, ¥, 


volornent of the spore-cluster; f, denotes the ¢ the 
fructificntion. "(rom Govbel's “Outline of Classification? be 


Tf the second binary division takes place in the same direction 
the first, the tetraspores ave arran; in linear it 
direction is transverse to that of first, the four spores cluster’ 
together, These, when separated by the ase of their envelope, 
do not comport themselves rt fae ied 

‘opulsive o1 8, are passively dispersed 
Faclt heir production, gh ‘Gkaein by celle 
division, and not being the result of any form of sexual 
the ‘tetraspores’ of the Floriden must be regarded, 
‘zodspores ' of the U/Tvacew, as gonids analogous rather to 
than to the sede of higher plants. It is now known that a 
generative process takes place in this group ; but the sexual organs 


FLORIDER | 561 

are not usually found on the plants which uce tetraspores 5 80 

that there would Ape egarrelerrnl orange ansny 
of itheridial cells are 801 

surface of the frond, more at the ends of branches, 

and in conceptacles. cir contents, however, 

are not motile ‘antherozoids,' but minute particles, known 


» and convey the fertilising substance 
roeAredlareery oe ilisation is effected by 
the attachment: os bE tue poUinaidto.the trichopyne, the walle ot 
which areabsorbed at that 0 that the fertilising material passes 

ahstiopiare: enitheace tuibe j one 


! 
: 
F 


the female tacle opens by « terminal orifice or 
ee are furnished with wing-like appendages. 
Detaaipetne =e Paper aS oe ape 
process ion is more comp! han this, 

and consists of two distinct stages. First, the trichogyne is impreg- 
nated by the poll ; and secondly, the fertilising principle 1s 
then con from the cells at the base of the tricho- 
gyneto thecells which ultimately produce the cai res, and which 
ee ee i even on a 
branch. This transference is effected by means of long 


ee ae pnanesion has ice pero been 

sea-weed ; |, considerin, 
{Fuearsate premio deere ree is = 
branch of microscopical observation which is more likely to reward 
the young investigator with new discoveries. 


oo 





9 562 
CHAPTER IX 
FUNGI 
Fone, as already mentioned, alge in the 
of chi and therefore in the absence of 
Saeay foeug oe tae eubetance by ae manta 


of must therefore, in all cases, be either 

or parasites, deriving their nourishment : \- 
materials, either, in the former case, from decay or vege- 
table substances, or, in the latter from 


The individual meee always consists of one or more Ayplie, 
slender filaments containing protoplasm and a nucleus (except possibly 


: : . 
siguent The odl-ral i ctspeasb of » silheiee dimeageiaee 


3 bin its ies from ordinary cellulose, since it is not coloured 
blue by iodine after treatment wi ric acid ; it is known na 
Fungus-cellulose or fungin. These hy may be quite distinct or 


very loosely attached to one another ; which penetrate thesoil, 
or "the aE! of bc al ‘on which Siete ne 
the imycele. In the larger fungi, as taushroom, 

pockicn above the soil is composed of « dense mass of these hypha, 
lying side by side, constituting a so-called bat 


| 


never a true tissue. In some families the hyphe havea 
leg aoe Sppomersten seri balls of great hardness a eat 
whi ave the power of maintaining their vitality for very 
periods, The modes of reproduction of fungi, both sexual and non- 
sexual, are very various. Among the latter the most common are by 
non-motile spores or gonids, ua By sotiepores, The former are very 
minute bodies, each composed of a single cell, or rarely of several 
cells, which are either formed within a spore-case or 

are detached from the extremity of hyphe by a process of 
off or abstriction, From their ex! lightness they are 
through the air in enormous numbers, thus bring al 
extraordinarily rapid spread of many fungi, such as mou! 
zoiispores are, like those of the lower alge, minute naked 
protoplasm provided with one or more vibratile cilia, by 


§ 


e 
th 








MYXOMYCETES 563 





here erred that of De Bary in his 
tony of the at fycetoroa, and Bacteria, 
of the structure of fungi, 


a oar kaw the rt of : 
ook 


s 





564 FUNGI 


may multiply by bipartition to an indefinite extent ; but after a 
time a ‘conjugation’ takes place between two of these my:xamctve 
(H), their substance undergoing a complete fusion into one body (I), 
from which extensions are put forth Abad and by the union of a 
number of these bodies are produced the motile protoplasmic bodies 
known as plasmodes, the ordinary form in which these singular bodies 
are known, These continue to grow by the ingestion and assimila- 





Dovelopment of Myxomycetes: &, plasmode of Didymiuit serpula; B, 
stages, a, a’, 6, of sporanges of A fate: & sive al 

Physarum album; D, ite contents escaping ; spore: 

coming flagellnted, und then amoeboid; H, conjugal 

I, have fused together, and, at J, are Beginning to put out extensions and ingest 

nutriment, of which two pellets are sen in its interior. 








tion of the solid nutriment which they take into their substance ; 
and, by the mmification and inosculation of these extensions, a 
complete network is formed. 

The filaments of this network exhibit active undulatory move- 
ments, which in the larger ones are visible under an ordinary lens, 
or even to the naked eye, but which it requires microscopic power to 
discern in the smaller, With sufficiently high amplification, a con- 
stant movement of granules may be seen flowing along the threads, 





566 FUNGI 


i 
i 


Lender age fsb utrd considered to to 
frosting now bn Tare nes aeaier in st 

same species, A striking 

well-known and very destructive disease of w! 


i 
ni 
eizts 
tL 
il 


known as ‘ mildew," produced Dn any srllghiy Se 
parasitic fungus Puecinia inis, Tt was observed 
wheat was especially liable to this disease i in the shy 


g 


bushes ; and it is Pat roams ite Mint na 
leaves, formerly known as Heidium berberidix, is the © 
generation of the same ee te Puceinia graminia is 


i 






Fro, 426,—Pwecinia graminis. From Pithe ‘omparative Morphology and 


Biology of the Fungi.’ larendon Prees) 


eee * generation, The complete cycle of devel it of 
the best aaten Oreaniaa such as the wniliew, is this. form 
known as Pucoinia Caserta oars teleutospores, thick-walled 
spores, borneusually in pairs, at the extremity of elongated cellsknown 
as basids or aterigmata. Each of these teleutospores gives rise, on 
germinating within the tissue of the grass, to a h; ‘or promyecele, 
the terminal cells of which develop, on slender basids, each a single 
spore or sporid. 'These sporids will germinate only on the leaves of the 


— 


UREDINE®; PERONOSPORE 567 


4 first of of interwoven, 

Sata 
a res dh 

Seaton unio arrears 
tacle, These are Sa ethene eae 

Wpemrmenre, smaller spherical or flask- receptacles, which 
neue gr ryt are filled with barren 
pen poreaee. oak hase exe othes sorter ypiee 

mt wi eration’ 
e808 
Seek er ees ther function, Th 
awcidiospores on. stems of grasses, 
slthe prodneing, ~ pea met, ing ah : 
bears aroundovalspore, the & pine 7 bee tpt epee es 
B 








_—Beidium of ant 
Re wotens of tbe"eada" thie parces ts tin 
same form, The same mycole which 
comstanly reproducing the Fite rise subsequently to hep hoe 
ete The fangs asl hibernate remains in a state of 
Dotitke Eemeaoeres the . 428) some ies grow on the dead 
Paligectactnaleacl os Seiclaste pcbece ara parauttio ithalivite 
pee re pes, , causing widespread diseases, such as the 
Laan it, On the mycele, consisting of a number of distinct sep- 
, are produced the aes odgones and antherids, 
is not effected b; motile antherozoids, as in 
Slit oe fungi po see) tp Sipe ary piers 

or tul @ process, the fortilixation-tube, 

4 are each single en! Siecle proitcedinsions 
oe one another ; the fertilisation-tube is produced from 
‘ofthe antherid which isin. immediate contact with the ovgone, 
discharges into the latter the contents of the antherid, thus 
its protoplasmic contents or ‘ odsphere’ to develop into the 


- 





568 FUNGL 


olspore.’ The further es enenies 
alot ndmar ase opr pees —— 


Nguutune ieealpian eee tpamstranen tt coed 
number of swarm-spores or zoispores ; each of these comes to rest, 


TE ae 
man 

pe gle leelae gt sad oe which are borne on special 

ches springing erect from the mycele, the sporyphores, or goni- 


#84 0 





Fto. (28—A-0, Gyatepur canidva: Hy Plytighhra difetent. A, bensels of 
mycole growing at the apex, ¢, with Aaseforta, B, betwoser Abe calla of ihatpitl ot 
Leidivm sativum; B, branch of myvele bearing Cee i D, E, formation of 











warm-spores from gonids; F, swarm-spores germinating; G, sWare-#porne 
Forminating ou u stomate aud pleccing the opidarta of Che stern Gf’ jelato oY Hie 
‘After De Brey; magnified about 400 timies. “Outlines of Claselfication and 





Special Morphology af Plants,’ by Dr. K. Goebel. 

diophores. A similar difference is exhibited in the further develop- 
ment of these spores. Either they germinate directly in water 
into a new mycele, or the protoplasmic contents break up into a 
number of zotspores which germinate in the same Tn those 
species which are parasitic on living plants, such as *hytophthora 
infestans which produces the potato-disease, and Cystopus candids, 


7 








the attacks of the itic Saproleguia 
ferox on the ted lesh of the animal. 

The Mucorini are filamentous fungi, 

zeeehios nee bd Tast, pends 23 their 

ent, but in 

earctitt Peetuetion: Te thae ly Z 

Ciag ie the most common pale herr eS ag rol 


rance on damp or ere 


decaying = au es. The ordi- ‘Sats of Chit 

an (a peaeas nasa IAEY isby a (6. 480, A), 
juced within a sporange (fig. 4: 

Sys sre borat ths oeeraes cients t unseptated 
germinating an @ mycele or from original 
filament. Several other kinds of non-sexual spores 
family, inching. handy reproductive cells 
pate within the ordinary of the hyphw. Sexual reproduc- 
tion takes: by means of sygospores (Crt but is at present known. 
only in a few species. Either from ordinary hyphw or from sporan- 
giophores spring a pair of short branches, the extremities of which 





Fro, 480—B, mycelo (throe days old) of Phycomyces wnitens, grown in a drop of 


‘the 





mucilage with a decoction of plums; the finest ramifications are omitted : 
conidiophore of Mucor in optical Jongitedinal section ; C, 
Fh ot acer race ooh ceareatta ot which eis 
‘Dre ‘are conjugating branches, 6 mitios a 
not yet conlascod, are alrendy cutoff hy traneyerse 
from the ‘coalescence of the cella aa. A, C, D, after aint 
B, from nature, slightly magnified, From’ Goebel's “Outlines af 
‘and Special Morphology.’ 


cut off conlexce to form the syaospore, which often swells toa consider- 
able size, and its outer coat mes SSaeweay Spe! covered 
with warts or other protuberances. rest the 
spore germinates, its inner coat of Cellulose ‘bursting pede! the outer 
warty and cuticularised epispore, and developing into the first germi- 
nating filament. 


ENTOMOPHTHOREE ; ASCOMYCETES 570 
Mot eas egal age bondi omg 





in 

common house-fly muse, In its . 
ares, 4 filaments of this plant out from the body 
of the fly like the ‘pile’ of velvet, and the from 
these in all directions form a white circle round it, as it rests motion~ 
less on a window-pane. The filaments which show themselves ex< 
eG nea mpeg ado Apap the inte- 
pari etd and this orginates in the find their 

into the ci fluid from without. healthy ays Ree eae 


ices abc age Pear area diye aar rag oes 
on some surface ; to germinate, sends 
outa a finds its way into rt either 


eel if mn sit as growth 
pore bathe Arn and destroys the life of the insect; it 
iy fing il mor a rapidly, the decomposi: paises ok tha dead 

more adapted than the living Sra to afford it 


eeThe “The Asoomyosten include an enormous number of species, most of 

which are parasitic on Te Nee tic on decayin, a ay 
of them microscopic, The mycele frnys consiate of branched and 

eet I atts In oy & comparatively few species is a sexual 

ane the special character of the group is the 

Prepon of ascospores ens peobanerosts sacs or tubes 

known as 2 ee Sead lected together in masses ; 

‘the collection of iy gre) me Py to the asct is known as the 

lara jael Recladg losing or bearing the hymenes as the 

Tts form and structure vary greatly in 

fae aiteren svelte of te fast The ascospores are always pro- 

oe within the ascus aly free-cell formation, and their nurnber is 

of four, most commonly eight. The asci 


ee aN ag enlarged club-shaped or sterile hyphzx, the 
In Bee ae eatas, ta aidiion to the ascospores, 


ordinary or conids are produced at the erates of 
mora eno 431, A). This is the case with a 
or Sirs of which the common blue mould, 

may be taken asa type. The familiar form of 


glaneum, may 
‘these moulds is that ‘in which pereane these spores in enormous 
quantities ; but, under certain itions, the sexual mode of repro- 








ASCOMYCETES 573 


to be alt distinct from the Ascomycetes. Of this 
o-called is bassiana (fig. 432), a kind of mould, the 
which is the real source of the disease termed muscardine 
carried off silkworms in large numbers, just when 
to enter the chrysalis state, to the great injury ct 

The. it presents itself under a peas ac 
forms (A-F), all of which, however, are of sateaasle 
consisting of elongated or rounded cells, connected 





Le-Botrytis bassiana: , the fangue as it iret appears at the orifices of the 

B, tabular filaments bearing short branches, as seen two days after- 
ne. view of the same; iS, D, appearance of filaments on the fourth 
Hak days; F, massos of matare spores falling off the branches, with filaments 
wading from them. 


tklace-like filaments, very nearly as in the ordinary ‘ bead- 
ls’ The spores of this fungus, floating in the air, enter the 
king-pores which open into the tracheal system of the silk- 
3 they first develop themselves within the air-tubes, which 
won blocked up by their growth ; and they then extend them- 
ithrough the fatty mass beneath the skin, occasioning the de- 
tion of this tissue, which is very important as a reservoir of 











simplicity of their character and in their *zymotic’ action, ‘The most 
familiar form of this family is the Saccharomyees,(Torula) cerevisie, 
the presence of which in yeast gives to it bd wie dae 
alcoholic iver in saccharine eae ne a drop of 
yeast is placed under a magnifying er or linmeters, 
it pe to contains lated autiber off be ameent tee eae 
averaging about yolsgth of an inch in diameter, for the most 

isolated, but sometimes connected in short series ;4 tach rit 
is filled with a nearly colourless ‘endoplasm,” eats exhibiting 


one or more vacuoles. When placed in a ferment fluid con- 
taining some form of nitrogenous matter in addition to sugar, 
they vegetate in the manner represented in fig. 433, Each cell 


z 
= 


uts forth one or two projections, which seem to be you: 
leveloped as buds or offsets from their predecessors 
the course of a short time, become complete cells, and 


1m from the researches of Pasteur that, although 
rainous maiter (auch 0s is contained in # sacclarine wort, OF 
favours the growth aud. reproduction of yeast, yot that it can live 
solution of pure sur containing ammonium tartrate with small 
ae ee ition of bape apres eee fu 
1¢ production of protoplasm, wl xoger and water supply. 
sai ydrogen ' 


i 
ail 


Aa 
Aah 






















SACCHAROMYCETES; BASIDIOMYCETES 575 


3 and in this manner the single cells of yeast 
ves, in the course of a few hours, into rows of four, 
which remain in connection with each other whilst the 
growing, but which separate if the fermenting pro- 
and return to the isolated condition of thuse which 
constituted the yeast. Thus it is that the quantity of 
introduced into the fermentable fluid is multiplied six 
during the changes in which it takes part. Under 
itions not yet determined, the yeast-cells multiply in 

namely, by the breaking up of the endoplasm into 
‘asually four in number, around each of which a new ‘cell- 

itself ; and these endogenous spores are ultimately set 
dissolution of the wall of the parent-cell, and soon enlarge 

themselves as ordinary yeast-cells, The process of the 
m of these spores resembles in all essential points the forma- 
3 and hence Toru/a is regarded as a low or degraded 
t order. Many other fungi of like simplicity have the 
act as ‘ferments’ ; thus in wine-making the fermentation 
of the grapes or other fruit employed is set going by 


° BWS&Qeg Garr 
% 723 Se RSA 
eQo & 
pee FER Qewe ESN 
« b e a 
inte t-plant, ri 
Seno ed wnccoaiva tages ol calleiiplntons 
felopment of minute fungi whose germs have settled on their 
‘these germs not being injured by desiccation, and being 
transported by the atmosphere in the dried-up state. There 
to believe, yaoreover, that a similar ‘zymotie’ action may 
by fungi of higher grade in the earlier stages of their 
the alcoholic fermentation being set up in a suitable liquid 
fas an aqueous solution of cane-sugar, with a little fruit-juice) 
wing in it the spores of any one of the ordinary moulds, suchas 
lium glaueum, Mucor, or Aspergillus, provided the temperature 
Wt up to blood-heat ; and this even though the solution has 
Ipreviously heated to 284° Fahr., a temperature which must kill 
rE it may itself contain. 

Basidiomycetes are distinguished by the entire absence, as 
‘at present known, of sexual organs, and by the formation 
tir conids or spores at the apex of special enlarged cells, the 
k They include the largest and most familiar of our fungi, 
as the genera Ayaricus, Boletus, Polyporus, Lycoperdon, 
lus, &c. They are saprophytes, obtaining their nourishment 
the decaying vegetable matter in the soil, stumps of trees 
te, among which the mycele penetrates, consisting often of a 
‘weft of septated hyphe, the ‘spawn’of the mushroom. The 
portion, known as the receptacle or fructification, bears either 





tf 
is 
a 


it 
i 
ued 
ag 


ELLEN 
Ha 
Te il 


ip 
=) : 
ae 


A 








the apex of the 
on ter euesunccetbe 
i ids are seen other 
| fel] si eae 

j i ust 
deh te 
Fin. 484—Agarious campestris, formation of the eystida, ‘fanction 
OB maguifed 620 tine ‘The portion masked O€ Which ia obscure, 
with fine dots is protoplasm. The bas Arty 
tly in. in 


reat 
ferent genera. They are always unicellular, and the 
consists of two coats, the endospore and exospore, the former of 
which consists of pure cellulose, while the latter is more or less 
cuticularised. On germinating the endospore bursts the 
exospore, and grows into a germinating tilament, from which i 
devel the ee) and on this Se sole 

i —The microscopic study i latterly 
acquired a new interest for the botanist, Somat remarkable 


| 


577 


‘LICHE! 





nil 4 ed 
‘gil ery 
He aa 

ne ae 
sipsgiio4i2842484 | egsiesaags ryczestpygsssg BS ? 
aaa 
EE mei 35 Ee nits 4 he a 3 itiee| 
pe Ae ere et 
hin aes HSE 


di 


PP 


578 uxor 





fungus-h; affording an example of the lar kind of mutual 
eaaatrn can ae tae 
if sex! luced * * usually tal 
cecticaliy to tha midst of straight Ay ted sterile cells termed 
porapliyee, 20 as to seas a Lye oe bie the surface 
of cup-shay receptacles termed apo or completely en- 
ol x eT Each of the asei contains a definite number 
of ves (usually eight, but always a ‘power’ of two), which 
are projected from the receptacles with some force; and their 
emission, which a to A pote to the orgs effects of moisture 
u the several’ layers @ receptacle, is often ‘con: 
caiaoealy for some time. The formation of these nhs as 
case of the ordinary Ascomycetes, is probably the result of « sexual 
union which takes place between the male pollinoids or *spermuatia” 
and the female ¢richogyne. These pollinoids are produced within 
antherids which are often specially designated ‘ spermogones,’ formed 


F 


J 





the main, that contain, as a no 
Sri can Gee ten that some of the 


It is impossible to take what we know of such a formas 2B, linsola, 
which has an easily demonstrated flagellate character, and reproduces 
in every fission a flagellum, common to both dividing forms, whicls 

at the moment of complete division, leaving each form 
Iss lam at Lt aea! enpertot an the primal = whence 
« fission arose—without ol ing how completely this coincides 
with the mode ie fission in ate a feos r ; sen Bat 
as an instance Cercomonas typica (named iven,! 
where the process is identical. tne the chars 
ting and subsequent resting after which swarms tomar 
from pores thus formed. But « fuller knowledge of B. Mineola 
inly wanting before we can deny the further . And 
this incidence is the more suggestive, since it is ic of the 
whole group of saprophytic monads, and their function is identical 
with that of the anne Bacteria, 

No doubt if such affinity were established, it would lead to much 
per Teepe at Pika 

Since there is an apparent a) if ly sega Jee 
Bacteria to those forms of Algwe which form the group of Vostocacee, 
these also would be brought nearer the Flagellata ; while the ae 
tozoa will have singular points of contact with these, one of 
has reference to the mode of sporing of one at least of the 


é 


saprophytes,* while it is suggestive that the same 
the affinity be established, would involvea connection ore Algw 
and the Fungi. 
colin, Bi ii, 198. * Mi 
"Colin Belirege, i rg, vel v, oe. pe neo ae ta else eee 


FORMS OF BACTERLA 581 




























only < definite results leading to a comprehensive view of the 
the Bacteria as a whole that can render generalisation 


baer st 
word Bacteria will be understood rod-shaped organic 
is the characteristic of the group. They are often less 
‘in breadth, and may be sphere-like or cylindrical cells. 
forms, whether longer or shorter, are possessed, as a rule, 
: ‘The mode of multiplication commonly observed is by 
ition. Theproducts of successive fissions may remain 
ina single filiform row loosely attached, or attached by the 
siemens 6 of the flagella, or they may at once separate 
nature of this simplest cell we have hitherto learnt 
ly little ; the: proto i ri is generally homogeneous, and 
it forms yl, although the absence of it and 
matters is a a disinet characteristic of the group. 
remarkable of the coloured forms uniformly tinged red 
and named by Professor E. Ray Lankester ;' other forms 
found by Van Tieghem, Engelmann, and Zopf. 
the protoplasm of the Bacteria, however, no nuclei have 
‘been. discovered, but a delicate investing envelope, probably 
thickening of the outmost area of the protoplasm, which is 
\tinous in its outer portions. 
of Bacteria have the power of entirely free move- 
uently this movement is coincident with a revolution on 
axis of the rod, curved or straight, and in the vast 
of cases this is directly correlated with a vortical action of 
flagellum—an action which may be seen with the utmost 
{ ie “peorer means be employed, in the case of Spirillum 
less easily, but with almost equal certainty, in the 
of other forms, not excluding B. termo. 
simplest forms in which Bacteria are found are as isolated cells 
or ovate shape ; these are known as Micrucocci ; but many 
are placed under this head are in reality immature and de- 
monads of the saprophytic group. 
rod-like forms are found isolated and free, or in chains. 
hort rods are known as Bacteria ; the long rods as Bacilli. 
which are fusiform in appearance are known as Clostridia. 
coiled rods or spiral forms are either (1) closely coiled, when 
wre known as Spirillum and Spirochete (more threadlike) ; or 
more openly coiled are known as Vibriones, 
are also very clongated filiform varieties known as Lepto- 
jsometi imes though rarely branched ; and Begyiatoa, thetilaments 
fixed at one extremity stretch the other free in the sur- 
fing fluid. 
at all these may be united by some interfusing gelatinous 
ial in which all action ceases, or is of the most limited kind ; 
hese living films, which appear on the surface or suspended in 
terior of putrescent fluids, are known as Zotiylu. They may 


* Quart. Journ. Micros. Sci, new series, xiii. 404. 





582 FUNGI 


also be found on the surfaces of solid bodies, where the putrefactive 
Na eae Leerentoig sires tne 
Bacteria is into 1. ous Bacteria ; 

ae ‘That this cl ts 





| 


acter suet papery leaves, and is con- 
Lccsentihing 3 arene ered Cae “exceed 


the condition 6 with an al solution of iodine. ¢ is a rod with five 
cells preparing to form d to / represent successive 8 of 
pair of rods in the act of mies and ft 
sn Ean Thecells which did noteontain, 
rished. is a quadri-cellular rod with ripe spores, ieee 
celled rod with thres ripe nasser 
ois the same an hour after ; pred 
after another two hours anda half, A! is two spores with the walls of 
faite Sponge ee ina pare tat bina <a 
five minutes later ; i, &,/ three 
""hacilaa auhracis col Boule eee Chak tage ae 
same division. #. anthracis is the form which has been sc 
be the virus of splenic fever or charbon. It is found in 
fusion in the blood and tissues of animals attacked 
‘The filaments or rods approach Ij in eres in 
grown in the blood of smitten animals, and 
three or four, sometimes five times this mati — are connected 


aE 


a 











ENDOSPOROUS AND ARTHROSPOROUS BACTERIA — 583 


together in the blood in straight rods ing ii = 
shows two filaments grown on a se mete, ret 
tion. heen egress ripe ae escaped. 
‘hse o gratin singe give vas to ew adc DE 


jore is beginning to germinate ; hh ; 
ey moeetiog time the Eh greta $ 
4 represents rods curved in a horseshoe 
Cae ‘the extremities connected, one e 
4 ‘one extremity sul ‘ 
ehttmcirictenmns \ | oe 
connected and already greatly in- , 
size. The whole represents a magni- 
- detailed Wustration of the 
a may 
2 ES geen oberg 
les, = 
la aed offiuents of Soo) Pade eg 
the fangus' i t 
Thay bare a thisenoes of pean ie nny be as a 
ly ly. Itis ati 


Ee 


fication of 


oH 


filis. (Brom De Bary's 

i as they are broad, and become at length ‘Fungi: 

oi but eventually attach themselves fie 4 

Soe ‘and come to rest, when they multiply by fission and accumu- 
in masses of oiglra. ‘They may develop into rods, and these 

again into the filaments after the rods have passed through the 


ing state.” 
ep u Re isasant oF dann not jes, Thee nets 
te flagella, and exhibit extremely active 
movement. The in these are as strong and easily seen as 
in the Spirillum volutens, and these forms were known at an carlier 


as 8. 
<s 440 shows at la ip of the attached filaments of Beggiatoa 
mare’ show Pactinnsdt Riese tact differing diameters ; Sshows a 
filament in the act of multipartition, ‘The small dark circles through- 
out represent the granules of sulphur ; 6 to 8 show fragments rich, 





Qfigr Ra rerdiiig > Sie Me Gey eid GY 
oo LOD 


[Pops 


POPSOCAAP EM AT O-Op) 





Fra, 440.—Reggiatoa alba. (From De Bary's ‘Comparative Morphology of Pangi.’) 


1 is magnified 540 diameters, the 


10 shows spores in movement, 
remainder 900 diameters. 


How por 


growth of the curved and 


of the same: A is a group of attached filaments ; B to 


Figure 441 shows the 


| 





the incites to : 
fnguiry and re- P12, $4-—Begyiatoa alba, curved and spiral 
race iis forme, Press De Bary’s ‘Comporative Morpho- 


modifications of the seprop! forms, to know the path by which 
bi became Hatte to put more into the hands of 
than could be accomplished by uny other means. 

termo is the most universally present and abundant of 

forms. Itix 1 to 1-5u long, and 0°5 to 0-74 broad, 
lumb-bell form, These Bacteria are usually seen in ‘ vacil- 
in their free state ; each cell hears a flagellum at 
(Be 442), whilst the double cells bear a fagellum 
‘formation of the second flagellum takes place 


tach e D 


ane 


i / 
+ CC —— ae 1 
ia ait eee ee 
‘ing out 0 ‘i¢ filament to form their second flagella, Magnified 2,000 
diameters. (Dallinger.) 
‘They are slightly curved rods and threads from 6p to 16m long, and 
varying in thickness from 0-5 to2y. ‘They have ieactet tale 
one at each end. They appear in vegetable infusions, causing fer- 
ee ade arth large Bae churncterdesa by 
Spirilla are t forms he 
their spirally formed cells and their motion, 
are fairly represented in fig. 44 by Spirillum wndula (Al 
Spirillum volutans (B). The threads of the former are from Lip to 
I'4p in thickness, and from Sp to 124 inlength. They are intensely 
active, and possess a flagellum at either end. ‘They are found in 
varying decomposing infusions. 
‘Smrillum volutans was known to and named by Ehrenberg. Te 
is from 1-Sy to 2-3p in thickness, and varies from ‘to 30 or more 
in length. They have distinctly granular contents, They have a 


1 Journ. of Roy. Micros. Soe. vol. i: (1878), 178 2 Ewart, Joe. eit, 


Py 













GERMINATION OF BACTERIA 587 


demonstrable flagellum at each end of the spiral ; a fla- 
distinctly suggested by Ehrenberg on account | of the vor- 
a visible in the fluid before this spirillum as it advanced. 
}whole it is surprising to find at this time what difficulty 
irs on the pat of some botanists to distinguish these mo- 
in the Bacteria, With the superb 6mm. power of Zeiss 
dry N.A. 0-95), all but the most difficult of these can 
relative ease on a dark ground with a 12 or 18 eye- 
they be examined alive with the flagella in motion. 
difficult ones (B. termo and B. lineola) more careful 
are required. 
inating power of the spores of Bacteria may be brought 
at once on their reaching ripeness, or they may be 
for an indefinite time, and again, on reaching suitable 
will germinate as before. “This wer is held in vari- 
by different forms, but the whole subject needs more 


wU 
Y IC. 
— B ey 


QS ess es 


4A, Spirillum undula, showing flagellum at each end. Mugnificd 3,000 
tara.” B, Spirilium colutane. Maguified 2,000 diameters. (Dallmger.) 


a and exhaustive inquiry. The spores of B. sbtilix retain 
vitality for years if kept in a dry air, while those of 
Gracis are stated by Pasteur to remain alive in absolute 
1"; and Brefeld found their power to germinate uninjured 
he lapse of three years in a dry atmosphere. He also 
proof against the boiling point of water, and even a hi 
‘tare ; but he found that fewer and fewer survived in boiling 
tt fluid until the end of the third hour, when all were de- 
L So Buchner found that the same spores were wholly killed 
ter three or four hours’ boiling ;? while Pasteur states that 
of uncertain spores can withstand a temperature of 130° C. 
s, however, uncertainty, because a want of uniformity, in the 
from various sources. 20° to 25° C. may be taken as the 
1 degree of temperature at which these organisms will freely 
ste; but B. fermo, for example, has been known to germinate 
5° C. to 40°C. 


1 *Charbon et Septicémie,’ Compt. Iend. Ixxxv. p. 0 
® Nuegeli, Unters. uber niederc Pilze, 1642, p. 22 













rr 





i 


i 
Hi 
i 


i 

i 
iy 
iu 
itt 
#1 


rel 
ite 
ig 
fe 
au 
a 
seh 


rather 
they are suspended, are the ive agents in the production of a 
cllac rosin in Ahoak ia ic tashlchichen acces ‘This vesicle 


must contain hundreds or for every one originally intro- 
duced ; and it is obvious that their altos eee 
ately 20 CES OE aes ee te idea that it must take 
lace by a like process of cell ment, Similar observations 


E 


been madi lande: and cattl } 80. 
ca tana puting maior sites of isos irre ae 
of infection to others, for precisely the same reason that a tub of 


7 


a 
named Vosema Bombycia, the mortality pena it being 
to produce a money loss of from three to 
sterling annually for several years following 1853, when it first 
broke out with violence. It has been shown by microscopic investi- 
gation that in. silkworms strongly affected with this disease, every 
tissue and organ in the body is swarming with these minute cylin- 
drical corpuscles about 42,4 long, and that these even pass into 
' As it soems unquestionable that igher Fungi ‘ conjugation” 

tales place at a esemep nth berry eo =a cme 
that the ‘granular spheres’ observed by Mr. Ewart in Baeillor 

scot to correspond with the ‘microplate ' obwerred by Prof. 


Bacterium rubescens, wnay be a product of potest in the inicrococeus wtage of 
‘these organisins, 








STRUCTURE OF MARCHANTIA sor 







with an ail 

below by a floor (a, @) of 
Saag ce ete at the 
La projection 
batloneet ‘alls whee its in 

yer 3 terior is occu 
bet ioe erg mang 
above when the observer 


i 


section should to traverse 
Pasig hoangeeon Saco 
oceupy the centres of the divi 


: 
i 
i 


2S A ead eereapeatl tia polymers A, portion: sour from 
q is t into com- 5 ty ivinions; 
wunication with eternal © Sh Comsat De centro ct eloeece 
atmosphere, the degree of that |} B, vertical section of the 

communication Teglatad © Bowiee ties Ms Sante Faren of Salinlar 
ty the lnmitation of aperture; feb Tah eptecnial Ines, nb, 

Fe shall hereafter ind that the forming testis mals’) ose 
Teaves of the higher plants con eee een oe raetis tonnage ite 
tain intercellular spaces, which full; i cella, forming the obtumtor-ting. 
also communicate with the ox- 
terior by stomates, but that the structure of these organs is far less 
oasis them than in this humble liverwort. 

‘ frond of Marchantia usually bears upon its surface, as shown 
‘Bg. 445, a number of little Cine aped genniparots con- 
cxplaces (Sg, 447) which may often be found in all stages of dovelop 
ment, and are structures of singular beauty. They contain when 
‘mature a number of li 
each of two or more layers of cells ; and their wall is sur- 

< a glistening fringe of ‘ teeth,’ whose edges are themselves 
Peon with minute outgrowths, This fringe is at first 
formed by the splitting up of the epiderm, as seen at B, at the 


5° 


green round or oblong discoidal gemune, 


i 


592 MICROSCOPIC STRUCTURE OF HIGHER CRYPTOGAMS 


hen the ‘conceptacle” and its contents are first making their 
sayater the surface, The little gemme are at first evolved as 







; these single cells, undergoing binary subdivision, evolve 
themselves into the gemmm; and these gemme, when mature, 
spontaneously detach themselves from their footstalks, and lie free 

within the cavity of the coneuptacle, 
. ‘Most commonly they are at last, 
washed out by rain, and are thus 
carried to di parts of the 
BY teal 

grow very wl sup- 
"Poeun, they nny Bo fone ne 
_ however, ro) f 5 
“ing whilst s6ill contained within 
(80. to wu stock 
tte cae 
or ; and many of 

the lobes which the frond 
of Marchantia puts forth seem 
to have this origin. The very 


i 
q 


made by Mirbel, ly 
watched the development of these 
gemma, that stomates are formed 
on the side which happens to be 
to the light, and that 
i i arores fori Srarate ea 

being apparently a 
ee eel 

HAT ti at 

Wa Marchentia popmorphar con- wards, since each has the one 
eeptacle fully: ex) rising from o¢ ing either stomates or 
the surface of the frond, «a, a, and Of developing : a 
containing gonidial gommw already thizoids according tothe influence it 
B, first a of receives. After the tendency to 
frond! showing the formation of'ts the formation of these ongans has 
fringe by the splitting of the epiderm, Once been given, however, ny fhe 


light upon one side and of darkness and moisture on the other, 
attempt to alter it is found to be vain ; for if the surfaces of 
young fronds be then inverted, a twisting growth soon restores them 
to their original aspect. 

When Marchantia vegetates in damp shady situations whieh 
are favourable to the nutritive processes, it does not readily produce 
the true fructification, which is to be looked for rather in plants 
growing in more exposed places. Each of the stalked peltate 
(shield-like) discs contains a number of flask-shaped cavities opening 
upon its upper surface, which are brought into view by a vertical 
section ; and in exch of these cavities is an, id wh 
is composed of a mass of *sperm-cells,' within which are developed 


Fa 





a al 


STRUCTURE OF MARCHANTIA 503 


erento ibe pliobs of Chard) anit eaviioas surmounted by a long neck 

ee cavity, The 

Waal ba lero bear on their 
under surface, at an early stage, concealed between membranes that 
connect the of the lobes with one another, a set of archegones, 
, like with elongated necks ( 448) = each of these has 
in its interior an ‘otsphere' or ‘germ-cell,’ to which a canal leads 
BEY Ce date She aloe esa od 





Fis. 449.—Elater 
and spores. of 

Marchantia, 
SPAcae raga covert the tem ct flattened fronds ; and thus the 
Sed is very extensively multiplied, every one of the aggregate of 


the type of ia ners as the Lehi 
section, liose is represent 

lungermannia, exceedingly esa plants, of a moss- 

on ving 'onmiet banks Carre situations, While 

sexual organs, and of the sporanges, resem- 

roland in main features that of Marchantia, the vegetative 

‘Organs are sey ills ing 0 sr ie 


iwhich 7 the uct of I bein, ble of 
pega Sor 
the structure 





FRUCTIFICATION OF MOSSES 595 


ls of extreme transparency, within which the protoplasm 
mtly be seen to circulate, as in the elongated cells of 


has commonly been regarded as the ‘fructification’ of 
wmely, the ‘urn’ or ‘capsule’ tilled with spores, which is 









B oon” ° 
© os 
“2 
Ne 
e oe Se 
@ eee 


<Antherids and antherozoids of Polytrichum commune: A, group of 
fa, mingled with hairs and sterile filaments (paraphyses). Of the three 
e, the central one is in the act of discharging its contents; that on the 
wt yet matare; while that on the right has ulready emptied itvelf, so that 
falar structure of its wulls becomes apparent. B, cellular contents of un 
& previoatly to the development oP ike antherozoids; C, the same, 
E the first appearance of the antherozoids; 1), the xume, ‘mature and 
Ging the antherozoids, 


t the top of a long foutstalk that springs from the centre of 
w of leaves (fig. £50, A)—is not the real fructification, but 
wet; for mosses, like liverworts, possess both antherids and 
nes. These organs are sometimes found in the sume envelope 
gone), xometiies on different parts of the same plant, some- 
ly on different individuals ; but in either case they are 
ea? 





Tea 


596 MICROSCOPIC STRUCTURE OF INGHER CRYPTOGAMS 


usually situated close to the axis, among the bases of the leaves. 
‘The ‘antherids’ are globular, oval, or ted bodies (fig, 451, A), 
of tions of cells, of the interior are ‘ sperm- 
cells,’ ench of which, as it comes to maturity, develops within itself 
an ‘antherozoid’ (B, C, D); and the antherozoids, set free by the 
celaps iy peesage Uist spans acs ov eciecntot Sart 
‘escay| a at the sumun 
‘The antherlds are generally surrounded by a cluster 


& 


peeling ay Sy ses 
ves On “fem 3 wi 1 or 
this and most other mosses, make their Jate in the 


summer, and remain through the winter. u 

neral resemblance to those of Marehantia (fig, 448), and the 
fertilisation of their contained ‘odspheres,’ or ‘germ: is accom 
plished in the manner described. The fertilised ‘embryo- 
cell’ becomes gradually di by cell-division into a conical 
Aare upon a stall; this at length tears across the walls: 
of the flask-shaped archegone by a circular fissure, ‘ing the 
higher part upwards on its su asa calyplar cx: Tea Vee 
a Olde lower part remains to form a kind of collar 
the of the stalk, known as the vagine, 

‘The urn, theca, or aio ee is the immediate product of 

the generative act, is at its summit by an or lid 
(fig. 450, B, 0, 0), which falls off when the contents of the sporange 





Fio. 458 
‘showing the peristome in situ, 


are mature, 80 as to give them free exit; and the mouth thus laid 
open is surrounded, in many mosses, by a beautiful toothed fringe, 
which is termed the peristome, This frv as seen in its original 
undisturbed position (fig, 452), is a beautiful object for the binocular 
ticroscope ; it is very *hygrometric,’ executing, when breathed 


Mouth of Funaria, Fio, 458—Double 
outh of spemnnge of Fv Fi elon 


Pontinalis 







SPORANGE OF MOSSES 597 


ement which is probably concerned in the dispersion 
Tn figs. 453-455 are shown three different forms of 
ead out and detached, illustrating the varieties which 
different genera of mosses ; varieties whose existence 
‘of recognition render them characters of extreme value 
tie botanist, whilst they furnish objects of great 
beauty for the microscopist. The peristome seems 
originally double, one layer springing from the outer, 
from the inner, of two layers of cells which may be 
uished in the immature sporange ; but one or other of 
tly wanting at the time of maturity, and sometimes 
obliterated, so that there is no peristome at all. The 
of the *teeth’ is always = ‘power’ of four, varying from 
-four ; sometimes they are prolonged into straight or 
The spores, or gonidial cells, are contained in the 
















Fis. 454.—Double peristome of Fie, 456.—Double peristome 
Bryum intermedium. of Cinclidium arcticum. 


part of the sporange, where they are clustered round a central 
ich is termed the columel. In the young sporange the 
ass is nearly solid (fig, 450, C), the space (/) in which the 
developed being very small ; but this gradually augments, 
pbeeoming more condensed ; and at the time of maturity 
jor of the sporange is almost entirely occupied by the spores. 
formed in groups of four by the binary subdivision of the 
which first differentiate themselves from those forming 
itself. The capsule and seta of mosses together consti- 
organ known as the sporogone. Thus, the ‘spore-capsule” 
iverworts and mosses, being the immediate product of the act of 
Bisation (which constitutes the point of departure of each ‘new 
tration’), is to be considered as the progeny of the plant that 
it: which, supplying the nutriment at whose expense it 
ops itself, acts as its ‘nurse.’ 
The development of the spore into a new plant commences with 
rapture of its firm yellowish-brown outer cont or exospore, and 
protrusion of its cell-wall proper or endospore, from the 












Fu beng of yt bon 
sphagnum, showing the nar ad 
ee ior; and their membranous walls 
tures; and the Jntecvening have large rounded apertures, by which 
Cl ieee etijet their cavities freely communicate with 
cells. one another, as is sometimes Fiseond 
evidenced by the of wheel: 
animaleules that make their habitation in’ these bers. Between 
these coursoly spiral cells are some thick-walled narrow 


cage 
Hl 
i 
: 
ot 


of lateral branches, each of the imbricated peri leaves: 

# single aes ee one err Sei 7 
roun rane ‘col tenuity. 
‘The female pee archegones, a sag se differ in structure 
from those of mosses, are grouped togethor in a sheath of deep green 


form and arrangement ; they are grouped in ‘catkins’ at the tips 
are sur. 





— -BOG-MOSSES 


and water, the are of great 
economy of Nature, with vegetation 
would otherwise be and servi 
moisture for the use of his 
Filices.—In the structure of 
eae plants; but this does not extend to 
the 5 ae emcrela: 
‘aaa iiss mosses, ved at a 
ot lim Aa the Gomer oe wal san 


at tn # and ipl lateral mies 
it is their arrangement i 
ele Ahecéramon brake which ‘walk’ of te leak 





of foot. 
showing: 


ves to the transverse section the mark- bundle of scalariform ducts. 


known as ‘ King 


Charles 
‘oak.’ “A thin section, especially if somewhat oblique (fg. 457), 
extremely well read ar a character of the ducts of the 


m, which are termed ‘scalariform’ from the resemblance of the 


tular markings on their walls to the rungs of a ladder. 


These 


600 MICROSCOPIC STRUCTURE OF HIGHER CRYPTOGAMS 


Benilet ot Sosiarttonm dada ons Spey 

sheaths of aclerenchyme, tissue a feat gallo ick 
ie csr rs on pation es 

section of the tem or some of ost arin nan een 


potty ing it strength and 

What is usually the fructifiention of the fern affords 
& ost inatifal and reaily propre las of opagueahjets fr the 
lower powers of the microscope ; nothing more being necessary than. 
to lay a fragment of the fond thxt bers eon the 
plate or to hold it in the stage-forceps, and to throw an juate li, 


it by the side-condenser. Te tally pnts ta the for 
of isola ye side concer, Te eal he frond termed sori, 





Fra, 45&—Leaflot of Poly- Fro. 450.—Portion of — ‘of Hamionitio, 
‘podium, with wort. = ‘with 


as in the common Polypodinm (fig. 458), and in Aspidinm (tig. 
460); but sometimes hese ‘sori’ are elongated into bands, as in 
the common Scolopendrium (hart’s-tongue) ; and these may coalesce 
with each other, so as almost to cover the surface of the frond with 
a network, as in Hermionitis (fig. 459) ; or they may form merely a 
single band along its borders, as in the common Pleris e 
The sori are sometimes ‘naked ’ on the under surface of the fronds ; 
but they are frequently covered with a delicate membrane termed 
the indusium, which may either form a sort of cap uj eae 
of each sorus, as in Aspidium (fig. 460), ora eit as in 
pendrivm and Pteris; or a sort of cup, as in ‘ (fg. 
Each of these sori, when sufficiently magthichit is found to 
up of a multitude of sporanges, or spore-capsules (figs, "S00, 461), 


isl 





have no annulus. It frequently happen that speci of fern- 
mete oe puibere faethe miicrossope wilh: are 

sporunges spires lispersed, whilst in others - 
vanced the | may all be closed ; others, however, may often 
be met with in which some of the sporanges are closed and others are 





N 
Fie. 400—Sorus and indusinm of 1a, 4i11.—Saras and cup-shaped 
Arpidium. indusivin of Deparia prolifer. 


and Sleoed be athe will sufficient Lyige the ruj BS 
Sporanges: dispersion the 3 may 
take whilst the specimen is under o| tion in 


i 


the tell of the I ‘hose sporanges have all 
» In sori wl ve all burst, 
the annuli connecting their two halves are the most conspicuous 


when a light is throw upon them, like 
‘ight brown hue. This is particularly 
fopendrium, whose elongated sori are remarkably beau~ 


for the mi in all their stages ; until quite 

need to te brought into view by turning back 

ids that cover ‘them. The commonest ferns, 

are found in almost every hedge, furnish objects of no 

Tess beanty than those yielded by the rarest exotics ; and it is in 

every epee most valuable training to the young to teach them 

font eect the mot aio beastie 

gen even in the most familiar, and ther |, speci- 
eS ‘ature’s handiwork. 

‘The ‘spores’ (fig. 462, A) set free by the bursting of the spor- 


it 
£ 

2 

: 


e 
i 
E 
E 


B 
i 


I 
; 

















(tig. 462, B, a) of the ‘ or an aper- 
ture in the outer spore-coat ; and moisture | absor! 

this, the cell becomes so distended burst! 
to 


as to! ° 
nd soon to ‘itself in « direction opposite 
of tis five rhiscle Ook potonsonree new cells by subdivi- 





Fig, 40—Derolopment of prothallian of Pris 
¢ sporange ; 

le ion to hp al bs siege iar seit elle: , 
hallioan te I } @, fires, second 

6, a the two lebes, and e, the Indewtation between ition; (ef tes-tarmed past af 
the prothollium; g, external coat of the original epore; &y 4, antherids, 


sion then takes place from its growing extremity ; this at first pro- 
coeds Speer 50S econ kind of confervoid fllament 
(C); but the aeclipenie of cells by subdivision soon takes 
transversely as well us donsitodinaliy, ao that a dattened 
expansion (D) is produced, so closely resembling that of a young 
Aarchantia a3 to be readily mistaken for it. This expansion, 

is termed the prothallivm, varies in its configuration in different 
species, but its essential structure always remains the same. From 
its under surface are developed not merely the rhizoids (a, kes 
Sere ab the| mans inet tae with 
moisture, but also the antherids arehegones, whi 

the true representatives of the essential parts of the flower of higher 
plants. Some of the former may be distingui at an early: 
of the development of the prothallium (/, 4); and at the time of 


# 











generative ‘gonid’ or detached flower- 
itself into a prothallium that may be likened to receptacle bearing 
the sexual apparatus. But this prothallium serves the further pur- 
pose of ‘nursing’ the eml originated by the 3 
which embryos finally a themselves, not, as in mosses, into 


a eS ee aren cof the ot arte 8 te 
Featiestuce samen te Lad pear e hie pea 


i 





a fern whose fine paper, ite 
Pasar ery tate gai pgtnty Pav fale Scared 
wpores. be hla eengormrnerpep ts ar 
= = 
Bottom of which i covered with water; apd a nveeted ever ly 
the requisite supply of moisture is wnxtieed, : ° 
‘oon udvance beyond the 
Ce a sich Neve sensined vakind sn Wheie growth ee aceon fae 
are 
covered perida. If the crop be now ey secisars Soe setae 
weeks, and then suddenly watered, a lange number of antherids and 
jand in a few hours afterwards the of 
Seailie fated found almost covered wilh meri > Sach Lad 
tea tran a ts lft hand that tan upper rerlat of ta Yrothalaan las pom 
thumb; nnd the thinnest possible sections are then ta be made with « thin narrow- 
\dicularly to its surface. Of these Lame gectge iy 
Draetice, ay be meade ‘no mone han one Beeb fs leoe Bal J 
robably lay open the canals of the ones; and within these, when examined 


M 

with a power of 200 or 300 diameters, anthereeoids may be 
Unguisbed. ‘The prothallium of the common Onmunia repalie 
afford peoalier facilltion for observation of the evelopment af the 
are produced at ite margin, 


i 


EQUISETACEA: 605 


mere sporogones, but, as in Phanerogams, into entire com 
in but the true generative which evolve 
clneatdcerd gene organs, 


frequently in Pleris srrulata the sporoph eration springi 
eprolallina nike de atest eee 


antherids, 
ne poe intentaces (Horse-tails) which seem owe 
to ‘erns their generative apparatus, tl 
peiblatalvonetative tortion i affords certain 
of considerable interest to the microscopist, The whole of 


ian 


objects: 


i 
| 
i 
‘ 





ited as the fructification of the Equisetaces: forms a 

‘cone or spike at the extremity of certain of the stem-like branches 

(the real stem being a horizontal rhizome), and consists of a cluster 

i which carries a circle of aporanges or 

longitudinal slits to set free the 
attached to it two pairs of elastic filaments 
elaters ; ee ieee, beet the 
represented at ugh more closely applis 

on the liberation of the spore, rameeadiy ea: 

shown at B, the slightest application of mois- 

ig to make them close together (the assistance 
in the dispersion of the spores being no } 

the spores have alighted on a damp surface, 1f a 

be spread out on # slip of glass under the 


ait 
eeieue 
Ay 


f 


i 





606 MICROSCOPIC STRUCTURE OF HIGHER CRYPTOGAMS 


field of view, and, whilst the observer watches them, a | 
neously: ion, thus an curious 
poiag gd pepe re epg cg 


Fie, 468 —Spores of Eqwizetumi, with theit elaters 


shadowing of the mode in which the generative is performed 
in Scorer plants, the ‘microspore * cheesy inertia 
the pollen-grain, while the ‘inegaspore ’ may be considered to repre+ 
sent the primitive cell of the ovule. 

ache alliance of Ferns is to the Lyeopodiacem (Club-mosses), 
a group which at the present time attains a great devel in 
warm climates, and which, it would seem, constituted a 
of the arborescent vegetation of the feet pri OS eee 
Lycopodiee: proper the sporanges are one kind, 
spores are of the same size, each, as in Ophiogloemem, giving origin 
to a subterraneous prothallium that develops both sntherids and 
archegones. The plant which originates from the fertilised 
cell’ of the archegone attains in colder climates only a 
yrowth, with a creeping stem usually branching dichotomously, and 
imbricated leaves ; but is distinguished from the trae mosses, not 
only by its higher general organisation (which is on a level with that 
of ferns), but by the character of its fructification, which is a club- 
shaped * spike,’ j Rapes small imbricated leaves, in the axils of which 
lie the sporanges. ‘The spores developed within these are remarkable 
for the large quantity of oily matter they contain, giving ‘them an 


Fi 


H 


be 





: higher Cryptogams, 
ing their soporte anaes poate dpsiriy trn 


plant, which is tedly the highest form of tation. But 
we have encountered a mode of te which, 
whilst ezsent the same thout the series, is no leas essen 
tially distinet from that of the the fertilising material 
Gas epraratialta’ tatag erticdiad! as tt Suahabrglstaunatsy Kid 
ments, the antherozoids, which find their way to the © ‘by 
their own independent movements, and the ‘ embryo-cell " being 
destitute of that store of Erapered nutriment which surrounds it in 
true seed, and supplies the material for its early development. 

In the lower Cryptogams we have seen that the fertilised odspore 
is thrown at once the world (so to speak) to get its own living ; 
‘but in ferns and their allies the ‘embryo-cell’ is nurtured for « 
while by the prothallium of the parent plant. While the true 
the ina is by the proper generative act, 

the multiplication of the individual is accomplished by the production 
and ion of * gonidial’ spores ; and this production, as we have 
seen, at very different periods of existence in the several 
r dividing the life of ench into two separate epochs, in which 
presents itself under two distinct phases that contrast 
remurkably with each other. Thus, the frond of Marchantia, 
evolved from the spore and bearing the antherids and archegones, 
is that which seems naturally to constitute the plant ; but that which 
represents this in the ferns is the mmute Marchantia-like 
prothallium, Tn ferns, on the other hand, the product into which 


—— 


608 MICROSCOPIC STRUCTURE OF HIGHER CRYP! 


the fertilised ‘embryo-cell’ evolves itself is that which 
regarded as te plant ; and this is represented in the li 
mosses by the sporogone alone.! We shall encoun} 
diversity (which has received the inappropriate designat 
nation of generations’) in some of the lower forms 
kingdom. 









1 For more detailed information on the structure and classifieatioy 
gams generally the reader is referred to Goebel's Outlines of Cla 
Special Morphology, and De Bary's Comparative Anatomy of thi 
and Ferns, translations of both of which have been published b 
Press ; and expecially to Bennett and Murray's Handbook of Oryplt 
published by Longmans (London, 1880) 














CHAPTER XI 
OF THE MICROSCOPIC STRUCTURE OF PHANEROGAMIO PLANTS 


Between the two great divisions of the Vegetable Kinga which 
Rebcae yn Shwe Phanerogamia the separation is by 


out the series. zane i tae bees, fee of Hs! series ws have sees 


foreshadowing of those the nurture of the fertilised 
aleaeieck eonatstcta taaycariicchive characters Oe Aka Phecmea® 
i ua ipeipanpep eer 
wer its, not are conspicuous 

parts of the flo flower. oftsa wanting, i da, te 2 nt group of 
Bymnognerne (astuding tho Conform and ) the essential 
parts of the generative sei tn nly 


pa iclieearcey Rare higher | Srreiogans. There a $5 bev: 


the act of Selita pened Os we pone For (1 

whilst in all the Cryptogams it is in the condition of at 

moring “an ss th a neg tg he 

to gerin- ese are conveyed to i oughout the 

Sf ga aeareatamast yee pepe naan ded 
wl 


Sa pe 


(3) while tha germ cll" or odsphere in the higher Cryptogams is 
contained in a structure that he peep ce hos the 
parent plant, it is not only formed and fertilised in all Phanerogams 
whilst still borne on the parent fabric, but continues for some time 
to draw from it the nutriment it requires for its development into the 
‘embryo.’ And at the time of its detachment from the parent the 
matured ‘seed’ contains, not merely an ‘embryo’ already advanced 
# considerable stage, but a store of nutriment to serve for its further 
during germination. As there is nothing parallel to 
sonsang Ceaptoms, it may be said that reproduction by seeds, 
se ee of flowers, is the distinctive character of neno- 
The peepee which ive fertilised and matured become see 
Goh ix all other Bhanevogans fd to m 
wi! nel to; 
Suna t ovules within an ‘ovary,’ Ea evala ae a 
RR 


Oo 


610 MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 


enolic warcoudedlby Haagen which remain u 
the sen’ Onell a the news teres gate 


and becomes the whose cavit 
coor nga id ity is oral ie 
end of Lae = Melee heeedirs on 


coll-formation, but 
eer PK 

represents the othe rine of the By a further process of 
Ses call foeraahioey Aaa cee ole To soa ee mane 
Ged ith oot, sone ee tr abe ie eal 


Saeco 
Tf the enibep rls aaa: sot 


Sa ie Sit x 
independent. parent in other cases: asa 
I ! Tn case it is taken into the substance of 


a 


a 


if 


series of ts. Fora large of the fabric of even the 
most sa toeately formed tree igs roy luding the ad nos actively con- 
Senn aes ae eee oe oe same 
kind as those which vot tie 


crrptouauss. For, anh ie sen sain and roots of ‘trees 


not met ith ay bt the ght ‘the special 
pffice of this is to afford mechanical eal rear as 
ponrepeace of Haid fee thd ts pe rn tua he ian sod 
gsonveyance ts the 
‘branches to the leaves ; Fecsbttsbetbenseitea oot) the pith 
‘and the cortex, with the ‘medullary rays," 
‘them, but the ‘cambium layer’ intervening between the bark and 
‘the wood nj too eke plea composed of er tepid 
‘of bark and wood takes “derma 
This tissue is found, in nae phot arin} eified 
‘for example, in the growing points of fitted dle 
‘and leaves, and ih the dower buds and sexual parts of sie flower ; 
‘it is only when thet organs attain an advanced stage of 
‘ment that woody stracturs is found in them, its funetion 
‘the stem) being merely to give sw to their softer 
the small pi ion of theit s which it forms is at 
‘seen in those beautiful ‘skeletons’ which, by a little skill and 
‘verance, may be made of leaves, flowers, certain fruits. 
‘softer and more viler Soe 8 tissue ed these ae is oees of 
more or less compactly having forms that 
‘approximate more. or af Psa to tl uaiae ‘or ovoidal, which 
_may be considered as their original type. 
Asa general rule, the ‘mia sie i preserved only when the 
eclls are but loosely aggregated, ax in the parenchymatous (or pulpy) 


S 


4 
{F 
Ee 


Hite 


fERea? 


| 
a 


PARENCHYMATOUS TISSUES 61r 


of leaves, which often forms a distinct layer known as the 

me’ immediately beneath the epiderm of the upper 
166), and it is then only that the “Tistinctness of their 
me evident. Wheri the tissue becomes more solid, the 
® wesicles are % 












20 that the form 
by the outline 
varies accord- 
the direction in Pio, 46¢—Section of leaf of Agave, treated with 
section is dilute nitric acid, showing the protoplasmic con- 
This is well Spidermal cow; 5, guard-clle of the som 
A cella; b, -cells of the stomate; 
the pith St he colin 'of parenchyine; dy their protoplasmis, 
> 
other rapidly 
trees, the cells of which, when cut transversely, generally 
@ircular outlines ; whilst, when the section is made verti- 
heir borders are’ straight, so as to make them appear like 
raig! Pper 

















Pho. 467.—Sections of cellular parenchyme of Aralia, or rice-paper plant: 
‘A, transvernely to the axis of the stem; B, in the direction of the axis. 


sor elongated prisms, as in fig. 466. A very good example of 
a cellular parenchyme is to be found in the substance known as 
veper, which is made by cutting the herbaceous stem of a 
eae plant termed Aralia papyrifera vertically round and round 


RRQ 


612 MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 
with a long sharp knife, so that its tissues may be (as it were) unrolled’ 
i . The ‘of its cells ed is. 

prinedie a shown sig 467 By butil Cho sam bo cat transtornds 
their outlines are seen to be circular so (A) 


cites Beppe, the cells have a very 
is in the direction of their geowth, whi 


li 
Hi 


t 
iu 
a 


Ef 
i 


i> 
EF 


pe 
b 
i 
ul 


zs 
: 
g 





’ of exogenous stems 

@), their growth being from 

the centre of the stem towards. 

its circumference, It is obvious. 

Sa thet Se Oe a aan 

transmitted i ion of greatest elongation, being in 

which they will have to pass through the least number of partitions ; 

and whilst their ordinary course is in the direction of the length of 

this roots, stems, or. beanclion, Hey abe Se eee ae 
medullary rays to find their way transverse di 


Ret 
pitetFe 

HoH 
bail 
feFhiediar 


Hl 
ee 
Atl 


e4 
BE 
5 
FE 
i 
i 
ai 





i 
i 
H 
; 
B 


Fro. 409.—Cubical parenchyme, with * 
Tate cells, fi iole of Nuphar Project into the cavity which 
[maa ited imal PVT P 


of 
lular tissue are extremely variable; for al their diameter 
is commonly between y}pth and y{gth of an inch, ocea- 
sionally measure as much as yyth of an inch across, in 
other instances they are not more than »}yth, 

The cells of a growing tissue are always formed, as we have seen, 
by cell-division, that is, by the formation of cellulose walls across 


g 





‘STRUCTURE OF THE CELL 613 
sets only io cdr Mice-veilod sole Gnade tarot 

‘i X ‘Itis in 4 line 
-demareation bocomes obvious in the form of an intermediate lamella, 
‘at one time called ‘intercellular D to be a 


Geer bettie otoular erectare of tie calor of adiffer- 


SEE 
4 
$24! 
ree 
rj 
a 
& 

Hi 

8. 

= 

: 

é 


es Vor the Lonidon pride (Saaxfraga seer eerie 
or emi 
Somiiy mann orient cnctel ri are turned brownish-yellow by 
iodine, while thelr membrane is only turned pale yellow, and in this 
‘be brought into view, when, as often ha 
i ishable, T€ a drop of the iodised each 
of zine be subsequently added, the cell-membrane becomes 


7 
t 


Le 
fe 
i 
fi 
H 
i 


Latte 
ae 
Hl 
i H 
5 H 
bg 


within its cavity, as shown in fig. 466. Tt 
, to regard this as a distinct membrane ; 

layer of lasm, natu- 
dense than that which it includes, but passing 


wits 
weer 
it 
ull 
ze 

f 


some stage or other of their 
of intensity, that curious 
has been already described as occurring 


Hil 
ue 
*ebegs 
it 
al 
a 
2FEa. 


ined poets, in the cells of which it continues for a 
period than it usually does elsewhere ; and among 
are Vallisneria spiralis and Anacharis aleinastrum (or 
odea canadensis), which are peculiarly fitted for the exhibition 
interesting phenomenon. Vallisneria is an aquatic plant 


ily 


ft 


614 MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 


that grows abundantly in the rivers of the south of but is 
Se ne enies eveat 
at of mou 
. n 


the section may be taken 
any one of the leaves ; but in winter it is preferable to select 
seve fr tho chsraton of de inteesteg [smitty ee 
serve observat 8 i’ 
little more can be seen with a }-inch ; but the sls-inch pelccel iets 
by Messrs. Powell and Leland enables the rs of the proto~ 
plasmic current, which carries along the particles of 

to be distinctly defined; and this beautiful may be 
most luxuriously watched under their patent ar, 

Anacharis alsinastrum is » water-weed which, having been acci- 
dentally introduced into this country many years ago, has 
spread itself with such rapidity th: hob onal aid eet asin 
many instances seriously to impede ir navigation. It does not 
require to root itself in the bottom, but floats in any part of the water 
it inhabits ; and itis so tenacious of life that even small € 
are sufficient for the origination of new plants. The leaves haye no 
distinct epiderm, but are for the most part composelof two layers’ of 
cells, and these are elongated and colourless in the centro, forming a 


H 


* Mr. Quekott found it the most convenient method of changing the water inthe 
jars in which Chara, Vallienerta, is, sre, growing: to Slaoe(thema 


uneher 
@ water-tap, and allow a very ‘stream to some, * sae 
the prolonged overtlow thus oceasioned all the impurw wales, the 
‘in apt to grow on the sides of the vessel, may be readily got rid of. 


CYCLOSIS OF PROTOPLASM 


towards the margins of the leaves, however, 
» He zo repems an. wiialaine 8 Soto 


if 
wn 





z 
i 
i 
g 
i Ee: 
i 
fut 


i 
i 
: 
3 
Re 
E F 
z 
E 
i 
+e 


i 
rl 
ul 
WG 
aiak 


! 
i 
ie 
E 


ie 
: 
s 
if 
af 
Ae 


no more than gyhyeth of an inch. When high powers and 
att ppeeeee ane employed, delicate ripples may be seen in the 
mic currents.' 
i however, is by no means restricted to subm ts 5 
a pe eee a 
: it it may ; resumed to iv |. Itis 
observable in the hairs i 


growth. The hairs should be detached by 
tearing off a pair of fine pointed forceps the portion of the 
r which they spring, care being taken not to grasp the 

hair itself, whereby such an injury would be done to it aa to k 
the Seas in it. The apochromatic hair should then be 
Pee ee opot.weter under thin glass ; and it will generally 
found advantageous to use a j-inch with the 12 or the 18 eye- 
piece objective with an achromatic condenser, The nature of 
the movement in the hairs of different species is far from being 
i Tn some instances, the currents in single lines 
the entire length of the calls, as in the hairs from the filaments 

Z ia virginica, or Virginian spiderwort (fig. 470, A) ; in, 
there areseveral such currents which retain their distinctness, 

in the jointed hairs of tho calyx of the same plant (B); in others, 
the streams coalesce into network, the reticulations of which 


i 


i 


t 


} Quart. Jowra. of Microee, Seienec, vol. ili. (1955), p. 277 aa 





rm 
Hee 
i 





fl 
Ue 
ai 
He 
Es 


in the hairs of the erm torn 

from its stalk or ». Tt is 

Se ae when 
ie it wl exhibits the cyclo- 

po tele 

for one or two day is 


ys, not 

the movement suspended, but the moving particles collect 
in little heaps, which are broken up again by the separate motion 

of pe ne when the stimulus of light and warmth 

a renewal of the activity. It is well to collect the about 
midday, that being the time when the rotation is most beri arms 
in- 
seen at 
while 


| 


the movement is usually quickened by artificial warmth, 
deed, is a necessary condition in some instances pe 
all. The most convenient method of applying this 





STRUCTURE OF THE CELI-WALL 617 


‘the object is on the stage of the microscope, is to blow a stream of 
Sn hitts Geet Gore nena oie oe el ate ae 
Mapa Masada aparece ile 
The walls of the cells of plants are frequently thickened by 
came which are first formed on the inner surface, and which may 


different appear- 
doesn to the manner 





oe er the. = 
present i 


dots, however, are not cote 
Fro, 471.—Tissue of the testa or seed-coat 
chan their ‘aspect might “Cr ‘staraniee: A, aa wen in section; 


bya B the surface, 
paar ot which’ the ples 


oe ‘so that he poeta ‘cell-wall there remains unthickened. 

ee lete CU tee tissue = Ate ne ha 
deposits: lerogen (a substance i when separat es 
wesinous and other ateae that are commonly associated with it, 
as found to be allied in chemical composition to cellulose) in succes- 





ia ' 
F16, 472.—Seetion of preset Fra, 478—Section of coquitla 
cutting the cells transverse nut, in the direction of the 


Jong diameter of the cella. 


‘give layers, one within another (fig. 471, A), which present them- 
selves a5 concentric rings when the cells containing them are cut 

5 and these layers are sometimes so thick and numerous 
as almost to obliternte tke original cavity of the cell. Such a tissue 
is known as sclerenchyme or sclerenchymatous tissue. By a con- 


618 MICROSCOPIC STRUCTURE OF PRANEROGAMIC PLANTS 


they hav 
of consolidation, still to remain 
the nutrition of the parts which such 
The t sometimes ass 
Jibres, which lie coiled up on the inner su 
form a single, a double, or even « triple or qi 
ATA). Such gpiral celle ave found. aDeHeR 






Fia. 475 —Spiral fibres of soed-coat of 
Collomia. 


oF 


A iil 
verbenace (wild clary), and some other plants, the membrane 
these cells is so weak, and the elasticity of theiv'fibres so great, that. 
when the membrane is softened by the action of water the fhres 
suddenly uncoil and el ite themsolves-(fig. 475), springing out, 
48 it: were, from the’ surface of the to which they give « 
peculiar flocculent appearance. This very curious phenomenon may 





STARCH-GRAINS 619 


be best observed in tho following manner :—A very thin trans- 
slice of the seed should first be cut, and laid upon the lower 
oe gene el shoei na ressed down, 
laced uy stage, 80 microscope may 
be exactl; eral ta the object, the power employed the 
1-ineh, “ns or }-inch. The cover of the aquatic box being 
then removed, a small drop of water should be placed on that part 
of its internal surface with which the slice of the seed had been in 
contact ; and the cover being replaced, the object should be im- 
mediately looked at. It is important that the slice of the. seed 
should be very thin, for two reasons; first, that the view of the 
may not be confused by their aggregation in too great 
; and second, that the rag is water pee be lay in its 

place by capillary attraction, ins running down and leavi 
As ‘as it will do if the glasses be too widely separated. es 
Te some part or other of most plants we meet with cells contain- 
ing granules of starch, which specially abound in the tubers of the 
akara bags in the seeds of cereals, Starch-grains are originally. 


iterior of chlorophyll-corpusctes, and therefore within 


we Ei 


Fi, 476.—Colls of pony filled Fio, 477-—Gronalos of starch ax 
with starch. toon nader polarivod light. 


the protoplasm-layer of the cell; but as they increase in size, the 
LL aye had ‘thins itself out as a mere oteting film, and at last 
almost enti disappears, So long as the starch-grains remain 
imbedded in the protoplasm-layer they continue to grow ; but when 
they accumulate so as to occupy the cell-cavity their growth stops. 
They are sometimes minute and very numerous, and s0 closely 
packed as to fill the cell-cavity (fig. 476); in other instances they 
are of much larger dimensions, so that only a comparatively smalb 
number of them can be included in any one cell ; while in other 
fanss, agnin, they are both few and minute, so that they form but 
a ion of the cell-contents. Their nature is at once 
detected by the addition of a solution of iodine, which gives them w 
beautiful blue colour. Each granule when highly magnified exhibits 
& peculiar spot, termed the hilum, round which are seen a set of 
circular lines’ that are for the most part concentric (or nearly 80) 
with it. When viewed by polarised light each grain exhibits a dark 
cross, the point of intersection being at the hilum (fig. 477); and 
when a ite plate is interposed the cross becones beautifully 
coloured, Opinions have been very much divided regarding the 
internal structure of the starch-grain, but the doctrine of Nigeli 





a 
i 
! 


yer i the 

where the formation of new layers takes bem thee 

ion of the older ones. pi dieresh mete the 
astarch-grains produced by any one species of plant are by no means 
constant, yet there is a average for each, from which none 
of them wi ; and by reference to this average the 
starch-grains of different that yield this product in abundance 
may be mi ly from one another—a cireum- 
stance of considerable co in commerce. The largest starch~ 

in common use are those of the plant (a of Canna) 


‘of ricestarch are x0 very minute eagnteeg 
eer * : 
other by 
orders, the stem, gpa pers are peated yang 


coloured juice, the eer ae exudes freely when the Chora 


ing it is wounded, and sar 

composition of the latex Ll pit ny sot in mltion powerfal lonrcaen 
alkaloids, as in the case of the opium. , or gumn-resins, Caou- 

tchouc and gutta-percha are the of tropical trees. and 
shrubs belonging to several natural orders. eel ee eae 
ciferous tissue are furnished by the ant enna 


which our 
common. field- is an example, such as the 
Aran and lettuce, Convair iaes rin or spurges, 

pocynacee, Moracese including the mulberry 
its of mineral matter ina crystalline condition, known as 

rey , are not unfrequently found in ae 
are _at once brought into view by the use of polarised 
designation (derived from fais, a eels is very appropriate to one 
of the most common states in which these bodies present themselves, 


that, namely, of bundles of needle-like crystals, lying side by side in 
the cavity of the cells; such bundles are well sen the cing 
immediately beneath the epiderm of the bulb of the 

squill. It fee not apply, however, to other forms which are 


scarcely less abundant ; thus, instead of bundles of minute 
single large crystals, octohedral or prismatic, are frequently 


i 





i 
F 
: 
5 
1 
2 
i 
: 


the leaf of Agave, Alo?, Cyeas, Et lartos, ke. ; 

the epi of the bulb of the hyacinth, tulip, and garlic ; the bark of 
Geeeenioxd Waste ot Ur coodtt dnapelis and ts oes 

; ‘ivand the elm. 
iA ange roti ofthe enon of the fabric of the higher 
plants is up of the substance which is known as woody fibre or 
tisene, This, however, can only be regarded as a 

of cellular tissue ; for it is composed of peculiarly elongated 

cells (fig. 493), ay Pointed at their two extremities so as to 
le-shaped, 


undergo consolidation by the internal deposit of sclerogen. It ix 


ting 
by their entire length, and strengthened by internal d it, must 
egal area tenacity than any tissue in which the cells 
but little from the primitive spherical form ; and we accord- 
ngly find woody fibre present wherever it is requisite that the fabric 
should possess not merely density, but the power of resistance to 
tension. In the higher cl of the vegetable kingdom it consti- 


tutes the chief part of the stem and branches, where these have a 











microscopic inspection of a minute it, even of a fossil wood, 
tha teibe to spideh ik beled of this kind, very 
characteristic of the wood of Conifer, not peculiar to that 
order, are known as‘ bordered pits, and the elongated cells in which 
they occur as ‘ tracheides.” a 


All the more perfect forms of Phanerogams contail 

part of their pt gregaria eter tic 
spiral cessels.' These have the elongated shape of fibre-cells 
e internal deposit, as in the spiral cells, takes the 


fibre winding end to en id Hirth) i F 
fibre may be single, double, or even quadruple, this last character 


z 
H 
2 
cre 


' So long, however, ax they retain their original cellular character, and do 
coalesce with each other, these fusiform spiral ells cannot be poten 
any more claim to the designation of wessrls, than have the cells of the 


woody tinue, 








difference are not yet certainly known. 


pala finds its way with tolerable facility 
beng various of cellular tissue, especially in the direc- 
Ee reeset Hengsh of the orld more direct means of con- 

ae between distant parts Se reauleed, for its active transmission, 
ake pital the pela of vessel known as ducts, which 
|, the partitions between them being 

ee ‘ ar iaioaied ‘The origin of these ducts is occasionally 
very evident, both in the contraction of their diameter at regular 
intervals, aind in the persistence of remains of their partitions (fig. 493, 
4, b); but in most eases it can only be ascertained by studying the 
blstory of their development, neither of these indications being trace- 
able. Tome of these ‘ducts ( 479, 2) are indi: from 
‘the spiral vessels already ibed, save in the want of elasticity in 
their spiral fibre, which causes it to break when the attempt is made 
to draw it out. This rupture would seem to have taken place, in 
some instances, from the natural elongation of the cells by growth, 
the fibre being broken up into ings which lie ematinan araled 
together, but more commonly at lerable intervals ; such a duct 
tobe annular (fig. 479, 1). Intermediate forms between the 

and annular noes which show the derivation of the latter 
the former, are frequently to be met with. The spirals are 
sometimes broken up ee | more completely, and the fragments of the 
fibre extend in various directions, | 80 a8 to meetand form an irregular 
network Li the duct, which is then said to be reticulated. The 
‘continuance of the deposit, however, gradually contracts the meshes, 
‘leaving the walls of the duct marked only by pores like those of 
rows cells; and such canals, designated as pitted ducts, are 
especially met with in parts of most solid structure and least rapid 
(fig. £ ads 3. he pares ducts of ferns may be re- 
as modification of the spiral; but spiral ducts are fre- 
ly to be met with also in the mpidly growing leaf-stalks of 
a such as the rhubarb, Not unfroquently, however, 
forms of ducts in the same bundle, as seen in fig. 479. 

‘of these ducts is occasionally so great as to enable their 
‘to be distinguished by the riveted eye ; they are usually 
stems whose size is small in proportion to the surface of 

which th they support, such as the common cane or the vine ; 


He a 


i 


es 
EES 
i 
| 





two pieces 
Givens bw cork elder pith, or ear 


in enses, 
ever, in which even this compression would be injurious, the sec- 
tions must be made with a sharp knife, the substance Jaid on 
the nail or a slip of glass. In dissecting the tissues 
scarcely any other instrument will be found really necessary than 
apets of needles (in handles), one of them ground toa cutting edge. 
he adhesion between the component cells, fibres, Cc, is often 
sufficiently weakened by a few hours’ maceration to allow of their 
readily coming apart, when they are torn asunder by the needle- 
points beneath the simple lens of a dissecting microscope. But if 
this should not prove to be the case, it is desirable to some 
other method for the sake of facilitating their isolation, None is so 
effectual as the boiling of a thin slice of thesubstance under exami- 


STRUCTURE OF STEMS 625 









er in dilute nitric acid or in a mixture of nitric acid and 
feof potassa. This last method (which was devised by 
‘fs the most rapid and effectual, requiring only a few 
Mor its performance ; but as oxygen is liberated with such 
to give an almost explosive character to the mixture, it 
‘put in practice with extreme caution. After being thus 
tissue should be boiled in alcohol, and then in water ; 
then be found very easy to tear apart the individual cells, 
of which it may be composed. These may be preserved 
in weak spirit. 

famd Root.—It is in the stems and roots that we find the 
variety of tissues in combination, and the most regular 
Biructure ; and section: of these viewed under a low mag- 



























ower are objects of peculiar beauty, independently of the 
b information which they afford. The axis (under which 
eluded the stem with its branches, and the root with its 
ns) always has for the basis of its structure a dense cellular 
3; though, in an advanced stage of development, this 
itate but a small portion of it. In the midst of the 
e we generally find fibro-vascular bundles, consisting of 
bre, with ducts of various kinds, and (very commonly) spiral 
| It is in the mode of arrangement of these bundles that the 
ital difference exists between the stems which are common: 
d as endogenous (growing from within), and those which 
correctly termed exogenous (growing on the outside) ; for 
former the bundles are dispersed throughout the whole 
‘of the axis without any peculiar plan, the intervals between 
ing filled up by cellular parenchyme ; whilst in the latter 
arranged side by side in such a manner as to form a cylinder 
which includes within it the portion of the cellular substance 
aa pith, whilst it is itself enclosed in an envelope of the same 
ee that forms the bark. These two plans of axis-formation 
ly characteristic of those two great groups into which 
gams are subdivided—namely, the Monocotyledons and the 
ons—will now be more particularly described. 

a transverse section (fig. 480) of a monocotyledonous stem 
ined microscopically, it is found to exhibit a number of fibro- 

bundles, disposed without any regularity in the midst of 
of cellular tissue, which.forms (as it were) the matrix or 
jf the fabric. Each bundle contains two, three, or more large 
which are at once distinguished by the size of their openings ; 
ese are surrounded by wooly fibre and spiral vessels, the 
e diameter of which is so extremely small that the portion 
bundles which they form is at once distinguished in transverse 
by the closeness of its texture (fig. 481). The bundles are 
jaumerous in the centre of the stem, and become gradually more 
d towards its circumference ; but it frequently happens that 
ortion of the area in which they are most compactly arranged is 
‘sheolutely at its exterior, this portion being itself surrounded 
im investment composed of cellular tissue only ; and sometimes 
ind the central portion, also, completely destitute of tibro-vascular 
as 


626 MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 


bundles ; eer ta meters Prete pen” pith, 
eect pea ibe pxveratec” AE ees tac tbegectcel 
very imperfect ; for we do no! eit central peripheral, 
portions ever separable, like Sih nnd bark, dom iia inteannatete 





Fu, 480, —Transveree section of stem of young palm, 


woody layer. Jn its oe state the centre of the stem is always 
filled up with cells ; not unfrequently disappear after a 
time, except at the neh, Naertng the stem hollow, as we see in the 
whole tribe of grasses. When a» 
vertical section is made of a woody 
stem (as that of a palm) of 


that, whilst they at their yj 

extremity into ci earn they 4 
at the lower end Neaarea aie eerace 
of the stem, and assist, by their in- 
terlacement with the outer bundles, 


these stems t. New rae. 
vasoular eerie) being continu. 
ally formed in the upper 
stem, in continuity with the on 
which are successively put forth at 

Fio. 4a Pectin o of cairns its soa eagation of the a ain ed 
nection of stem of Wanghic cane, in 

contribute but little to the increase of 

its diameter. For those which are most recently formed eal poze 
into the centre of the stem during the higher part of thir ce 
and usually make their way again to its exterior at no great distance 
below ; and, when once formed, they receive no further additions. 








STRUCTURE OF STEMS 627 


Te was from the idea formerly entertained that these successively 
formed bundles descend in the interior of the stem tht its entire 





bark—the first (a) central, the last Fo. 4¢2.—1 of the first 

(by and aving the —formstion of “a, exogenous 

ve interposed ters Caste ates yeh Mb keer ie 
ing made a Sa nddles left uh 

(d, art by neato rays we a 

com} of unchanged cellular tissue 

(c,¢) that pass between the pith and the bark, ‘The pith (fig, 483, a) 
almost com] ; 


‘eiasie netics ocen) = tecnganl areotias Whee 
lon) & al en 
ly formed it has a greenish hue, and its cells are filled with 
fluid ; but it gradually dries up and loses its colour ; and not un- 
its component cells are torn apart by the pay growth 

n 


of em) that irregular cavities are found in it; or if 
5 





° e CS 
Fin. 458. —Transverse section of stem af Clematis: a, pith; b, 2, 
) ¢, ey anedullary rays. 





6, woody bundles; 





the stem should increase with extreme rapidity it becomes hollow, 
the pith being reduced to fragments, which are found adhering to 
its interior wall. The pith is immediately surrounded by a delicate 
membrane, consisting almost entirely of spiral vessels, which is 
termed the medullary sheath, 
‘The woody portion of the stem (fig. 483, 5, 5) is made up of woody 
eee 





628 MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 
fibres, usually with the addition of ducts of various kinds ; these, 


however, are absent in one large the i or fir-tribe 
sell te allie (Age AST AOU} ia Nee cells or 
tracheides ave of unusually diameter, and are marked by the 


bordered pits already described. In any stem or branch of more 
than one year's growth the woody structure presents a more or less 
distinct appearance of division into concentric the number of 
which varies with the age of the tree (fig. a ‘he composition of 
the several ring, SESS CaENNEN BONSS so many it 

layers, is uniformly the same, however different their thickness ; but 
the arrangement of the two principal elements—namely, the cellular 
and tho vascular tissue—varies in different spocies, the vessels being 
sometimes almost uniformly diffused through the whole layer, but in 
other rare being estan Re) inner Le ep ears 
cases, again, are di with o certain +1 

(if hae mela may be allowed), so as to give a curiously 





Fico, 4$4.—Transverse sootion of stem 
‘of Rhamuus (buckthorn), showing 
concentric layers of wood. 





figured uppearance to the transverse section (figs. 484, 485). The 
general fact, however, is that the vessels predominate towards the 
inner side of the ring (which is the part of it first formed), and that 
the outer portion of each layer is almost exclusively com of 
cellular tissue, Such an arrangement is shown in This 
alternation of vascular and cellular tissue frequently serves to mark 
the succession of layers, when, as is not uncommon, there is no very 
distinct line of separation between them. 

The number of layers is usually considered to correspond with 
that of the years during which the stem or branch has been. ; 
and this is, no doubt, generally true in regard to the trees of 
temperate climates, which thus ordinarily inerease by ‘annual layers.’ 
‘There can be no doubt, however, that such is not the unit rule ; 
and that we should be more correct in stating that each layer indi- 
cates an epoch of eegetation, which, in tempernte climates, is usually 

‘ (but not invariably) a year, but which is commonly much less in the 





i 
3 
i 
; 
4 
i 
sit 
iz 
Hy 
9 
z 
7 
= 


It 
their 


may even occur as a consequence of an interruption to the processes 
of juced by seasonal \—as by heat and it 
by ere Hae L Earsepiery raped pe a 
of temperature in « tree that requires heat—w: appear from the 
with which a double or even a multiple succession of rings 

i ‘in transverse sections of wood to occupy the place of a 
single one. Thus in a section of hazel stem (in the Author's posses- 
sion), of which a ion is represented in fig. 486, between two 
layers of the ord thickness there intervenes a band whose 
breadth is altogether less than that of either of them, and which is 





abe 


Pio. 484—Portion of transverse section of stem of haze?, showing, in the portion 
@, 6; ¢, six narrow layers of wood. 


yet composed of no fewer than six layers, four of them (c) being very 
narrow, and each of the other ‘eae 4) being about as wile as 
these four together. The inner rings of won, being not only the 
oldest, but the most solidified by matters coe within their 
component cells and vessels, are spoken of ively under the 
i duramen or ‘heart-wood.’ On the other hand, it is 
the cells and ducts of the outer and newer layers that the 
sap from the roots towards the leaves ; and these are conse- 
quently designated az alburnwm or ‘sap-wood.’ The line of demar- 
cation. the two is sometimes very distinct, asin lignum vite: 
and cocos-wood ; and as a new ring is added every year to the ex- 
terior of the alburnum an additional ring of the innermost part of 
the alburnum is Lukes Sapa consolidated by internal deposit, and is 
thus added to the exterior of the duramen. More generally, how- 
ever, this consolidation is gradually effected, and the alburnum and 
duramen are not separated by any abrupt line of division, 
The medullary rays which cross the successive rings of wood 
the cellular substance of the pith with that of the bark, 
and di each ring of wood into wedge-shaped segments, are thin 
plates of cellular tissue (fig. 483, ¢, c), not usually extending to any 


630 MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 


Greak depths Luts vera ciewstioy ‘It is not often, however, that 
character can be so clearly seen in a transverse section as in 
pling Are oe or eed they are Poly ato ron 





Fro, 487,—Portion of transverse section of the stem of eater: a, pithy 
‘by by D, woolly layers; ¢, bark. 


different directions—namely radial and tangential—with the trans- 
verse, Three such sections of a fossil coniferous wood in the 
Author's possession are shown in figs. 188-490, The stem was of 
such large size that, in #0 small a of the area of its transverse 
section as is ted in fig. 488, the medullary rays seem to run 
rallel to each other, inst of radiating from a common centre. 
They are very narrow ; but are so closely set together that only two 
s Suc lig eC ae 

uct ing present) in- 

tervenc between any pee ey 





verymuch 
ing in a horizontal direction the 
Fio, 488.—Portion of transurso section of tracheides which lie to 
te mtn ay one another verily. Ad 
showing part o a n the tangent 7 
eee =o 150) rhe ts be a 
tion at right angles to that of 


of the plates thus formed has a very limited depth from above down- 
wards, and is composed of no more than one thickness of cells in the 
horizontal direction. A section of the stem of mahogany taken in 
the same direction as the last (fig. 491) gives a very good view of the 
cut ends of the medullary rays as they pass between the prosenchy- 


STRUCTURE OF STEMS 631 


matous colls ; AI ite es I atid rd ‘thick- 
nts being composed of two or threerows of phates a byside. 





tion, wo a to ent across the 
anedullary nays. 





oot @ a) intervening cers the = 
among whic 
eae ase rene ctsae are scattered ; Shilst in 


the tangential section they are observed 
to be not deeper than the precedin, 

from above wards, but also to Lae 
a much greater thickness. This section 
also gives an excellent view of the ducts, 


fossil wood in the Author's possession the 
medullary rays constitute a still larger 
Beogertion'ot the stem ; for in the trans- 
. 492), they are seen as 
Ses teoad' bands (0, 4), alternating with 
Ss is le less tontecer as eetekt a n t 
whilst in the tangential section (Ge. 495) 
cut patentee ities of the medullary rays occupy a very largo part 
‘of the area, having apparently determined the sinuous course of the 





fie 


53 


632 MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 
chymatous cells, instead of looking (as in fig. 490) as if 
Pad forced their Hs these ea! which en hold Beet 





v7 
+) (Soe 
Fio. 492—Transverse section of @ Ero, 498,—Vertienl (tangential) see- 
fowsil wood, showing the medullary tion of the same wood, showing the 
TaYs, o, 0, 4, @, 4, @, Funning neorly uchymatons celle peparated 
parallel to’ each oth thie Ey the medullary cays and by the 
mings of large ducts large ducts, & b, 6 & 





of the prosenchiyaistovs tinsue. 
straight and parallel course on ¢ither side of them. The medullary 
rays maintain a connection between the external and the internal 
bbs 





Fios, 494 ond 495,—Transverse and vertical sections of m fossil wood, 
showing the separation of the woody plates, aa, a, by the very 


the 
lange modullary rays, bb, 
parts of the cellular tissue or findemental parenchyne of the stem, 
which have been separated by the interposition of the wood. 








i 
: 





u og in number those 
of the v the innermost being the last formed ; but no such 
succession can be distinctly traced either in the cellular envelope or 
in the sub Faber ee aka ome Oe ent, 
in thickness by additions to their interior, whilst their 

tions are frequently thrown off in the form of thickish plates, or 
detach themselves in smaller and thinner lamin. The bark is 


always the wood by the cambium layer, which is the 
part “patsy aeeclper beh eG Nia lager etd con- 

of semi-fluid matter ; but it is really made up of 
cells of a very delicate texture, which gradually undergo transfor- 
mation, are for the most part converted into tracheides, 
ducts, vessels, &c, ese materials arc so arranged as to 


. Th 

ent the fibro-rascular bundles of the wood on their external 
thus forming ® new layer of ‘alburnum, which encloses all 
oes t preceded it; whilst they also form a new layer of ‘liber’ 
on the interior of all those which preceded it. They also extend the 
wry rays, which still maintain a continuous connection between 
the Av by bark ; and a portion remains unconverted, 40 as 
always to keep apart the liber and the alburnum, This type of 
is termed exogenous ; a designation which applies 
correctly to the mode of increase of the woody layers, although 

{as just shown) the liber is formed upon a truly endogenous plan. 
jumerous departures from the normal type are found in partiou- 
Jnr tribes of dicotyledons. Thus in some the wood is not marked by 
concentric circles, their growth not being interrupted by any seasonal 
change. In other cases, again, exch woody zone is separated from 


634 MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 


the next by the interposition of a thick layer of cellular substance. 
Sonntine ood i rel athe Ik (in uthus), 99 that 
are 






Fo. bgerroige vita mea WS 
stem of aw elimbiy ib (Arristor 
lochia I) trom Rea vata 


bundles being themselves separated from each other by plates of 
cellular tissue, which still remain to connect the central and the 
peripheral portions of that tissue. ‘This first in the formation 
of the exogenous axis, in which its principal pith, wood, 
bark, and medullary rays—are marked out, is seen even 
stems of herbaceous plants, which are destined to die down 
end of the ap (fig. 497) ; and sections of which 
easil: |, are most interesting microscopic obj 

star eg difference between the end and the exogenous 
types is manifested in little else than the disposition of the fibro- 
vascular layers which are scattered through nearly the whole of 
the fundamental tissue (although more abundant towards its 
exterior) in the former case, but are limited to a circle within the 
esl pheral portion of the cellular tissue in the latter, Tt is in the 
ater development which takes place during succeeding years in 


= 


e5 
3g 





Dg eth xylem and phloem 
phloem portions of otc 
se is usually the case, the bundle is said to 

ither portion encloses the other like a cylinder, 


‘The structure of the rvots of endogens and exogens is essentially 
the same in plan as that of their respective stems, Generally 
speaking, however, the roots of exogens have no pith, although they 
pee ce: and the succession of distinct rings is less 
in it is in the stems from which they diverge, 
es which proceed from the larger root-fibres 
acentral bundle of vessels will be seen enveloped ina sheath of 
cellular substance ; and this investment also covers in the end of 
the branch, which is usually somewhat dilated, and is furnished at 
its extremity with one or more layers of cells, which are constantly 
off, known as the pileorhiza or root-eap. The structure 
iaktrce sain sachin ee peas ee common 
every wi gle root down 
from its lower surface. The central fibro-vascular cylinder which is 
characteristic of the finer roots of exogens, as well as of endogens, is 
a ed by « single layer of cella very clearly differentiated from 
‘the fundamental known as the bundle-sheath, 
Wo have seen the peculiar form assumed by the bundle- 
Sera the stom of ferns and other vascular cryptogams. 
‘structare of stems and rots cannot be thoroughly examined 
in any other way than by making sections in different directions 






i 


a 


! 





bottle of weak spirit until they be mounted. For the minute exami- 
nation of their structure, they may be mounted either in weak 
irit or in glycerin-jelly, Where a mere view only is needed, 
er mounting answers the Hise suffi well 5 there are 
maar eeesy @kiAe et of Clematis, of which transverse sections: 
rat icker ordinary make very beautiful epague 
wai mounted dry on a blak, romod.Canad baksam al at 
be recourse to, except in the case of vory me sections, as 
usually makes the structure too ti, reaver sections, 
however, when slightly charred by heating between two plates of 
ass until they turn brown, may be mounted with advantage in 
Ganada balsam, and are then very re specimens for the Lat 
microscope, The number of beautiful nnd interesting ol 
may be thus obtained from even the commonest trees, shrubs, and 
herbaceous plants, ab the cost of a very small amount of 
can searcely be conceived save by those who have 
to Rhee  ondactal ei amy ; and a ber sah sections: 
made in different parts of the stem, especially neighbourhood 
of the ‘growing teint, will reveal to the eye of the physiologist 
—!| 












‘of leaf of Indian 
aan shoring stonaten 


4, ta). The es of these cells is different in 
ta ; thus in th of the Yucea (fig. 
499), Tris (fig. 303) and most other mono- 
ted, and ¢ an approach to a 
their margins eee in the Yuece 
‘inutely sinuous or crenated in the Indian corn. 
i ei cies hands Cie calla €f tha epiders 
the rounded form, but their margins usually 
 sinuosities, s0 that they seem to fit together ive 
dissected map, as ia seen in the atts the apy “apple 
. Even here, however, the cells 
which overlies the ‘veins’ of the feat ies ee 
approaching that of the wood-cells of which these veins are 
composed ; and it seems likely, therefore, that the elongation 
of the ordinary opiderm colls of monocotyledons has reference to 
that parallel arrangement of the veins ‘which their leaves almost 


of leat of Fre. 400,—1 
corn (Zea 





ie 
em 


a i 
5 re ll i 
ee 


ad 
I 
ia 


= 








| 


STRUCTURE OF LEAVES 





; in 
thas a glandular body at 
its base, containing a peculiar secretion ; when this cecretion is of 
an irritating quality, as in the nettle, it constitutes a ‘sting” A 
great variety of such organs may be found by a microscopic 
examination of the surface of the leaves of plants having any 
kind of superficial investment to the epiderm. Many connecting 
links present themselves between hairs and scales, such as the 
stellate hairs of Deutzie sabre, which a good deal resemble those 
within the air-chambers of the yellow water-lily (fg. 469). The so- 
called ‘gh * or ‘tentacles’ of the sundew (Drosera) are not 
really but outgrowths of the internal tissue of the leaf, each 
‘ po eat hearer ey bel th 
man) its, i joxe belonging to the 
tribe, has its cell-walls Srientel. with silex, fike that of 
Westcme: #0 that, when the organic matter seems to have been 
rid of by heat or by acids, the forms of the epidermal cells, hairs, 
es, ke. are still marked out in silex, and (unless the dissipa- 
tion of the organic matter has been most perfectly accomplished) 
are most beautifully displayed by polarised light. Such aiton 


A 





640 MICROSCOPIC STRUCTURE OF PHANEROGAMIC PLANTS 


Bair Soe tn wile kager repel or Oem 


"moe strengthened 6 
: one common 
| rows of little cu, 











meet with any conformation at all to be com in 
with that which has been described in the humble 
Stomates are usually found most abundantly (and sometimes exelu- 
sively) in the epiderm of the lower surface of leaves, where ear ore 
into the air-chambers that are left in the i 

next the inferior epiderm ; in leaves which float on the surface of 
water, however, they are found in the epi of the surface 
only ; whilst in leaves that habitually live entirely oseeel a 
there is no distinct epiderm, so there are no stomates. Tn the erect 
leaves of , the Jris tribe, &c. they are found equally (or nearly 
80) on both surfaces. Asa general fact, they are least numerous in 
succulent plants, whose moisture, obtained in m scanty supply, is 
destined to be retained in the system ; whilst they abound most in 
those which exhale fluid most readily, and therefore absorb it most 
quickly. It has been estimated that no fewer than 160,000 are con- 


oe 


‘STRUCTURE OF LEAVES 





S HNTE(H GT Fi nat WML 
Pane i iyi all au utaee 
. aie: a2ees te pel aH gz yet? 
il ‘ i Hlth el HOAs 
i 2783 pi i Gulia eee) 

; Hat a tet ; DH UHL Bile 
a BAT Sea He eet 
Hoa nen ear HL 
be feigiul iz iis HATE aan 
in aeae HUH etc 
i RPE PA TB la 


TT 


layer of colourless cells, d, d, down to that lower portion of 
where its two halves diverge from one another, we find that it there 





proportion of their 
variety in leaf-structure is ited by the water-lily and other 
plants whoxe leaves float on the surface ; {aches tatene ees 
ment is entirely reversed, the closely set layers of green 

being found in contact with the lower surface, whilst all the 

part of the leaf is occupied by a loose spongy peed ee 
a very large number of air-spaces that give to the leaf ; 
and these spaces communicate with the external air through the 
numerous stomates, which, contrary to the general rule, are here 
found in the upper epiderm alone. 

The examination of the foregoing structures is attended with 
very little difficulty. Many epi may be torn off, by the ex- 
ercise of a little dexterity, from hs Ee 
invest without any preparation ; this is especially the case wi' 
monocotyledons generally, the veins of whose leaves run parallel, 
and with such dicotyledons as have very little woody structure in 


—— 


+) 9) STRUCTURE OF FLOWERS 


ves ; in those, on the other hand, whose leaves are furnished 
; rela ted veins to which the epiderm adheres (as is the caso in 
be 


é 





by fa }), this can only be detached by first 
the for a few days in water; and if their texture 

be particularly firm, the addition of a few drops of nitric 

to the water pect eateries epiciee nopre caaliy separable 
derms may be advantageously mounted either in spirit or in 
glycerin-jelly. Vi sections of most leaves may be made by 
a sharp by acareful manipulator ; but it is generally 
i placing the leaf between two pieces 
either of very soft cork or of elder-pith or carrot, or imbedding it in 
paraffin, In order to study the structure of leaves with the fulness 
that is needed for scientific research, numerous sections should be 


bhai 
will found to answer sufficiently well, 
‘Many small flowers, when looked at entire with alow 


are striking microscopic objects ; and the 
pel af tho young, in cuok Gee eer mia acy eaibeoer 


ie 





3 
Bg 
iF 
: 
i 


Ht 
iu 


i 
i 
ft 
3s 
F 
i 
z 
F 
i 
Es 
? 


general 
and petals, which constitute the ‘perianth ' or 


E 
i 


floral envelope, closely corresponds to that of leaves, the chief differ- 
ence in tho peouliac chanaeok hue which the chlorophyll almost 


in the latter class of o1 and very frequently 
former There = some ae porary whose cells 
interesting peculiarities, either or marking, in 
distinctive coloration ; such are those of rig 
ion is represented in fig. 506. The dif- 
of petal—when it has been dried after strippi 
immersed for an hour or two in oil of turpentine, 
in Canada balsam—exhibit a most beautiful variety 
coloration, which is seen to exist chiefly in the thick 
of the cells; whilst the surface of each cell presents a 
curious opaque spot with numerous diverging prolongations 
TT 


Fee 
re 


a 
FL 


fe 
| 
| 


ty 
it. In the first afford a of 
staying thet fora of ‘reo sal formation Wh woe posal to 
the pare concerned in the reproductive process, and which consists 
in the development of new cell-walls round a number of isolated 
masses of protoplasm forming parts of the contents of a £ 

cell,’ go that the new cells lie free within its cavity, instead of being 
formed by its subdivision, as in the ordinary of multiplica- 
tion. If the anther be examined by bers detr!o- s 
of its development within the young flower-bud, it will be found 

be made up of ordinary cellular Laberge ee! no peculiarity 
anywhere shows itself ; but a gradual * ye ‘takes 
place, consisting in the development of a set of very large cells in 
two vertical rows, which occupy the place of the Toeuli or * 
chambers’ that afterwards present themselves ; and these 
cua to the pollen-grains, whilst the r 
to form the walls of the pollen-chambers. 

formed within ‘ mothor-colls,’ the endoplasm of each 

into four segments. These become invested by a double en’ 

firm extine, and a thin intine, ond they are set free, when u 
by the bursting of the pollen-chambers, It is not a little curious 


Pateae 


POLLEN-GRAINS 645 
that the: ‘of cells which lines the pollen-chambers should i 
ina oe ees aan 

ture, tl saprrorel rye laters of Marchantia (fig. 449). 


The oa eager! seems to depend in 
mode of division cavity of the parent-cell into quarters ; 
ing, it approaches the spheroidal, but it is very often 
and sometimes tetrahedral, It varies more, however, 


of fluid, which usually takes place when the pollen is 

in contact with it, is to soften down angularities, and to 

the cell nearer to the typical sphere. The extine or outer 

coat of the pollen-grain often exhibits very curious markings, which 

seem due to an increased thickening at some points and a thinning 
away at others, peerage mp ive to the surfaco 
80 a resemblance to a stratum of cells (fig. 507, B, C, D) 

very careful examination can detect the difference. Th 

ipa mere space oe eno protuberances, as 

at A, is a very common feature ; is seems to enable 

pollen-grains more lily to hold to the surface whereon they 

‘be cast. Besides these and other inequalities of the surface, 

or slits in their 


¥ 


e 


#1 


Le 

ie 
Ba 
2c8e. 
Fe 
ie 
he 
SEF 


not absolutely deticient at these its, but is only thinned 
the pores are covered by little dise-like pieces or 

off when the pollen-tube is protruded. This action 
llen-grains fall upon the surface of 
with a viscid secretion ; and the 
first mere protrusions of the inner coat of their cell, 
themselves between the loosely packed cells of the stigma, 

grow downwards through the style, sometimes even to the length of 


: 
E 


FEF 
" 
| 


jl 
4 


several inches, until they reach the ovary. The first change, namely 
the: of the innermembrane through the pores of theexterior, 
be made to take place Sealy ize moistening the pollen 

ith water, thin syrup, or dilute acids (different kinds of pollen- 


; 
ie 
iF 


i 
oH 





HIT 
i 


e 





E 
E 


i 


_—Pollons a wa rove tO it), Ws an opaque | 
"thalia B, Cobew prea a C, Passi. this may be done 
carrulea; D, Ipomea purpurea. advantage in the case 


common 
conn Unyhavespene, viet rg propertin of the fa 
soon ve whilst a , 
is yet udlacharged, and being laid doen a a8 

they have begun to wither, between two pitces of smooth 
paper, then subjected to moderate pressure, and 


upon a surface. They are then, when Pope, 
most benutiful objects for objectives ot t 1, 1}, or 2-in. focus, 
lange 


tea 


especially ‘with the binocular microscope. 


1 Te sometimes hay that when the of or firs is set 
uantitien of { are ened by the int ica gat Eines Sout een 
Blantations in which ft bas besa produced, and are deposited ax @ fine yellow 
” Lacy, Capri solphur as to be mistaken for it. 
pra 5 of op mm (such ws ove in the 

1879) hos tri the * 
was at hand. Its truo nature is at once revealed by placing a few grains of it under 
the microscope. 


1 HEHE 
ee 
rau na He Wel 
1H Hee sete ai ace 
ii: jet aver ana 
F BS = 2 Sm 1 | i nn sge } a 
i a Hi Hl Het 
i : | bed i a 
va Hoe i Halil Hl 
sf Hatta Hl 


= 


u ently be met with.’ The entrance of the be 
th oe gosy be most pt ge a pee pile eae 
stole only to tear open with a 
the mee ey eat is just and to detach. 
ovary J at wtheing 


placenta the ovules, almost 1 one of will be 
a pollen-tube sticking in its farina: These o1 
too 


5 
ffs 
tie 


e 
é 
ie 


a 2 < 
where 
the 
cerned ; and for this, 

4 primrose) has is 
recourse to by Hof- 
meister, whilst Schacht 
recommends _Lathreem 
squamaria, Pedicwaris 

justris, and partiou- 

‘ly Pedicularis sylea~ 
tica, 

We have now, in 
the last place, to notice 
the chief points of inter- 
est_ to the microscopist 

no 50a Konda a sng ake done which are furnished by 
poppy mature seeds. Many 
er); CG, Antierhinum (any ; 
Fete Benen E, Bin jignomia, sy te kinds of 


ata 
eh 
£4 
Ej 


curious, and some are very beautiful anes 


natural state under a low magnifying power, "Thus the seed of the 
rer (fig. 508, pe nb epalet ner reticulation upon its surface, 
Sungai eect cee te 
Thato! the pink( £0" wi ivisions, 
one i whiel Saha cia | bright black crs erica] knob in its. 
middle ; that of Amaranthus kh has its surface traced. 


with extremely delicate markings m (B) 5 that of ee is. 
strangely irregular in shape (C), an almost like a piece of 
furnace-slag ; and those of many Hignoniacee: are remarkable for the 
beautiful radiated structure of the translucent membrane which 
surrounds them (E). This structure is extremely well seen in the 
seed of the Ecvremocarpus scaber, a half-hardy climbing plant 
common in our gardens; and when its membranous ‘wing’ 
examined under a sufficient magnifying power, it ix conaliee to be 


STRUCTURE OF SEEDS 
by an extraordinary elongation of the cells of the seed-coat 


i 
g 


at the margin of the seed, the side-walls of which cells (those, 
namely, which lie in contact with one another) are thickened s0 a3 
to form radiating ribs for the support of the wing, whilst the front 
and back walls (which constitute its membranous surface) retain their 
original Le ony Arse Speehat ae pvp oo ion of 
Late rege their interior, In the of Dietyoloma. ie 
besides the | ‘wing’ prolonged from the edge of the seed- 
cont, there is a series of successively smaller wings, whose 
form concentric over either surface of the hear 

e pre 


ie 
5. 
a 
Eady 
ue 
il 
= if 
Al 
He 

FE 


i 
i 
H 
' 
i 
i 


a 
H 
; 
; 
: 


a8 transparent objects in Canada balsam : 
ydrangea, Monotropa, Orchis, Parnassia, Pyrola, Saxi- 
umbelliferous ts generally are remarkable 


Ey 
a 
Fe 
aut 
gine 

i 
Pye se 
lel 
Bik 
BEES 


ls of the star-anise, and the densely con- 
‘shells’ of the coquilla-nut, cocoa-nut, &e, 
\oticed, we cannot here stop to do more than. 
‘ity of the constitution of the husk of corn- 
grains. these, as in other grasses, the ovary itself continues to 

seed, giving a covering to it that surrounds the testa, 
closely adheres to it. The ‘bran’ detached in grinding consists 


LE 
Fret 
u 


4 A part of these lists have been derived from the Micrographic Dictionary. 





‘ + 651 hse 39 


CHAPTER XII 
MICROSCOPIC FORMS. OF ANIMAL LIFE—PROTOZOA 


‘ 9 ¥ 
PasstnG on, now, to the Animal we directing 
Pe > Lents he areas pro ep 2. in 





that ayer into the space left void by the dissolution of the central 
cells ‘morula.’ This gastrula-stage,* as we shall see hereafter, 


+ The termes and blast lly used by English embryologis 

Berm se een env noe re 

eee 
‘the moruta into two layurs, and. by pearinde at one point 

‘an orifice which leads into the central cavity: thie oavity is original 

tion cavity of the morula, and not « fresh cavity, as in *invaginate gastrale,’ 











Mywomycetes or the Chlanydomyaa alvo 





line of division can be drawn, the only j ‘separa 
tion here adopted being that the eaies of ee ‘former neem to- 
be rather with the palin iy vegetation, whilst the whole 
Peet bens pede Praeersteseycre ope 
by which into undoubted rhizopods, leave no- 

Babe af er claim ive lace in the animal kingdom. 

: 
Monznozoa. 

A characteristic example of this lowest protozoie: presented 
by the Protomyxa awrantiaca (fig. (i 30), 0 maron sat pres 
orange-red colour, found by Professor kel sn deed sheila of 


Spirula near the Canary Tslands. In its active state it has the 
stellar form shown at F, its arborescent extensions ae and 
inosculating so as to form a constantly changing network of proto- 


PROTOZOA—PROTOMYXA 653 


plasmic threads, along which stream in all directions orange-red 
granules, obviously belonging to the body itself, together with foreign 
organisms (6, c)—such as marine diatoms, radiolarians, and infusoria 
—which, having been entrapped in the pseudopodial network, are 
carried by the protoplasmic stream into the central mass, where the 
nutrient matter of their bodies is extracted, the hard skeletons being 
cast out. Neither nucleus nor contractile vesicle is to be discerned, 
‘but numerous floating and inconstant vacuoles (a) are dispersed 














Fie, 509—Protomyza aurantiaca: A, encysted statospore; B, inci- 
plent formation of swaru:-xpores, shown at C escaping from’ the oyxt, 
At D swimming freely by their flagellate appondages, and at E creep. 
ing in the amerboid condition; F, tally developed reticulate organism, 
showing numerous ricvoles, a, and captured prey, b,c. 


through the substance of the body. After a time the currents 
become slower; the ramified extensions are gradually drawn in- 
wards; and, after ejecting any indigestible particles it may: still 
include, the body takes the form of an orange-red sphere round 
which a cyst soon forms itself, as shown in A. After a period of 

jeseence the protoplasmic substance retreats from the interior of 
the and breaks up into a number of small spheres (B), which, at 
first inactive, soon begin to move within the cyst, and change their 
shape to that of a pear with the small end drawn out toa point. 


654 MICROSCOPIC FORMS OF ANIMAL LIFE 


‘Phe cyst then bursts, and the red pear-shaped bodies issue forth 
into the water (C), moving freely about by the vibrations of flagella 
formed by the drawing out of their small ends, just as do the 
flagellated xodspores of protophytes. These bodies, being withou! 
trace of either nucleus, contractile vesicle, or Sea are to be 
regarded az particles of simple homogeneous proto] to which 
the desi; ton plastidules has been apy tely given. After 
about a day the motions cease ; the agen ero drawn in, and the 
plastidules take preety and lead on ife of Preecons putting forth 
inconstant ial processes, and engulfing nutrient particles 
in their substance (D). Two or more of these amebiform bodies 


5 











Fro. 510.—Vampyrelia spirogyre an seen at A sacking ont contents 
of Spirogyra-coll; at B in encysted condition, the eyst a enclosing 
granular protoplasm }; at CG, division of contents of eyst into 
tetrarpares, of which one is escaping in the amenboid condition 
to develop itself into the adult form shown at D. 





unite to form a ‘plasmodium,’ as in the Myzom; ; its paeudo- 
podial extensions send out branches which inosculate to form a net- 
work ; and the body grows, by the ingestion of nutriment, to the 
size of the original. In this cycle of change there seems no interren- 
tion of a generative act, the coalescence oft the amerbiform plastidules 
having none of the characters of a true ‘conjugation,’ But it is by 
no means improbable that after a long course of multiplication by 
successive subdivisions some kind of conjugation may intervene. 
Another very interesting ‘moneric’ type is the Vampyrella, 
of which one form (fig. 510) has long been yee, in its encysted 
condition as a minute brick-red sphere attached to the filaments of 








Py 
oO 


Bey 


TA Fy 


af 
at 





656 MICROSCOPIC FORMS OF ANIMAL LIFE 


Intermediate between the foregoing and the ‘ reticularian * rhizo- 
pods, to be presently described, is another Gree protozoin dis- 
covered in ponds in Germany by MM. Clapartde and Lachmann, 
and named by them Licberkuchnia Wageneri! The whole sub- 
stance of the body of this animal and its pseudopodial extensions 
(fig. 512), is composed of a homogencous, semi-fluid, granular proto- 
plasm, the particles of which, when the animal is in a state of 











Fio, 511.—Vampyreta _gomphonematis; 

Gomphonema attacked by Vampyre , erneyaterd state ; 
}, b, cysts with contents bresking mp into tetraspores, a, a, 
yrelia sucking out 
emptied frostules. of 
Vempyrella creeping 














ubont by ite extended paeudop 


activity, are continually performing a circulatory movement, which 
may be likened to the rotation the particles in the protoplasmic 
network within the cell of a Tradescantia, It is amarked peculiarity 








19 Etudes our les Aes, Geneva, 1838-1801, The bewutifal 
been reproduced hy the Author 


has 
the Foraminifera. 






in Phate I of his Ing Ww to the Stu 








pip, Fed ‘aoe tala Fia, 018 —Léeberhuchnia Wagener(. 
arrives ata point where a fila- f 
ment bifureates, it is often arrested for a time, until drawn into one 
or the other current; and when carried across one of the bridge- 
like connections into a different band, it not unfrequently meets a 
the ite direction, and is thus carried back 
to it having proceeded very far from it, The 
pa ean peg ReASaibcats bans 
tinually changes in its own arrangement, new filaments 
i hoi different directions, sometimes from its margin, 
from the midst of its ramifications, whilst others are 
retracted. Not unfrequently it happens that to a spot where two or 
more filaments have met, there is an afflux of the protoplasmic sub- 
stance that causes it to accumulate there as a sort of secondary centre, 
from which a new radiation of filamentous processes takes place. 
‘Occasionally the ppecadopedia are entirely retracted, and all activity 
censes 5 so that body presents the appearance of an inert lump. 
vu 


H 


i 








rT Loboac are com, rely active in their habits, moving 
freely about in search of which is still received into the sub- 


exudation from the surface of their bodies of some material 
(probably chitinous) which hardens into a membrane, or by aggre- 
and uniting grains of sand or other small solid particles, which 
i upinto ‘tests.’ A large proportion of them are inhabit~ 
ants of fresh water, and some are even found in damp earth. 
Reticularia.—This ae is very characteristically represented by 
the Gromia (fig. 513), some of whose species are marine, and 
are like ordinary Yoraminifera, among tufts of corallines, 
alge, &c.; whilst others inhabit fresh water, adhering to Conferve 
pestle plants of running streams, It was in this aoe the 
presence of a nucleus, formerly supposed to be wanting in Reticularia 
vous 





MICROGROMIA 661 


fas the curious habit of aniting with neighbouring individuals, by the 
fusion of the pseudopodia, into a common ‘colony,’ the individuals 
sometimes remaining at a distance from one another as at A, but 
sometimes aggregating themselves into compact massesasat B, The 
nearly globular thin calcareous shell is prolonged into a short neck 
having a circular orifice, from which the sarcode-body extends itself, 














royromia tocialis: A, cold 
m undergoing transvur 
(sone of them 
formation and ese 





y of individualsin extended state, 
fission; 1, colony of individuals 
ed from the principal mass) in compact state; C, D, 
of swarm-spore, seen free at E 












giving off very slender pseudopodia which radiate in all directions. 
‘A distinct. nuclens can be seen in the deepest part of the cavity ; 
while a contractile vesicle lies embeclded in the surcodic substance 
nearer the mouth, Multiplication by duplicative subdivision has 
been distinctly observed in this type ; but with a peculiar departure 








HELIOZOA 663 


one of the pseudopodia (which have firm axis-filaments clothed 
ic gets eee enmity emina tpn ina te 
mode in which the p thus taken captive is introduced into the 
vig enough to. 2 to deopreperie iene = 
[oy hytanicpay sas i ein ae gee plane 





Fro, 616—delinophrye sol: 4, figure showing the wide racuolated cortical 
layer or eotosaro (x) and tho fine granulated endosare (xx); , central 
nucleus, az, axial ts of psendopodia; cv, contractile vacuole ; x food- 
mass incloped in a lange food-vacuole, B, a colony of four individuals, after 
treatment with acetic acid: x,3, and x, webefore; r, r, vacuoles, C, a cynt; 
nS weal ele pepe it alps eyat from ip log — 
encaping, incl inner en a itech, 

after Grenacher, Stein, and Clenkowaky.) [ 


visible movement of the latter, much in the same manner as in Gromia. 
When in either of these modes the food has been brought to the 
surface of the body, this sends over iton either sidea prolongation of 
its own sarcode-substance ; and thus a marked prominence is formed 
(fig. 515, A, x), which gradually subsides as the food is drawn more 
com into the interior, ‘The struggles of the larger animals, and 
the ciliary action of Infusoria and Rotifera, may sometimes be 
observed to continue even after they have been thus received into 








664 MICROSCOPIC FORMS OF ANIMAL LIFE 
the body ; but these movements at last cease, and the of 
digestion begins. The alimentary substance is into one 


‘of the vacuoles, where it lies in the first instance surrounded 
by liquid ; and its nutritive portion is gradually converted into 
an indistinguishable gelatinous mass, which becomes 

with the material of the sarcode-body, as may be seen the 
general diffusion of any colouring particles it may contain. Several 
vacuoles may be thus occupied at one time by alimentary particles ; 
frequently four to eight are thus distinguishable, and occasionally 
ten or twelve; Ehrenberg, in one instance, counted as many as 
sixteen, which he described as multiple stomachs. Whilst the 
digestive process, which usually occupies some hours, is going on, 
a kind of slow circulation takes place in the entire mass of the endo- 





Fro. 618.—Actinosphoerivm Bichornii: m, endosare; 7, ectosnre; 
©, ©, contractile vacuoles, 





sare with its included vacuoles. If, as often happens, the bod: 
taken in as food possesses some hard indigestible portion (as the shi 
of an entomostracan or rotifer), this, after the digestion of the soft 
parts, is. gradually pushed towards the surface, and is thence extruded 
by a process exactly the converse of that by which it was drawn in. 
Ii the particle be large, it usually escapes at once by an opening which 
extemporises itself for the occasion ; but if small it sometimes glides 
along & pseudopodium from its base to its point, and escapes from 
its extremity, 

The ordinary mode of reproduction in setinophrye seems to be 
by binary subdivision, its spherical body showing an annular con- 




















666 MICROSCOPIC FORMS OF ANIMAL LIFE 


ceding, but its mode of reproduction presents some marked peouli- 
arities. In many, if not in all cases it commences, as first observed by 
Kolliker, with the conjugation of two separate individuals, The binary 
segmentation is sce by a withdrawal of the lopodia, even 
their clearly defined axis becoming indistinct and finally disappear- 
ing ; the body becomes 
enveloped by a clear 
gelatinous exudation, 
which forms a kind of 
cyst; and within this 

process of binary 
subdivisionis repeatedly 
performed, until the 
wipes single mass is 
repi by a sort of 
morula, each spherule 


tinction between the 
central and cortical 
regions, the former in- 
cluding a single nucleus, 
whilst the Lae is 

iby silicions 
pm a firm in- 
vestment. After re- 
maining in this state 


young Acti ve 
come forth spring 
without this silicious 


investment, and gradu- 
ally grow into the like- 
ness of their parent.! 

A large number of 
= new = en fresh- 
O18, — Cl ane: A, al water forms this ty; 
pe a Diver ante lie aie are being frequently 

‘and two contractile vesicles near ite opposite end. brought under notice, 
of which the: Mee ruling 
elegans (fig. 518) may be specially mentioned as present an 
obvious transition to “the Regeln type. This has been ‘foond 
in various parts of the Continent, and also (by Mr. Archer?) in 
Wales and Ireland, occurring chiefly in dark ponds shaded by 
trees and containing decaying leaves. Tts soft sarvode-body, whi 
is not differentiated into ectosare and endosare, is encased by a 
silicious capsule of spherical form, regularly perforated with oval 

















n the result 
spharrinie 





ho artificial division of Actinoupherrium soe K. Brandt, Ueber 
_ ruber, Berichte d. Naturs. Get ae 
mat. xxvii. . 


A 
-water Radiolaria in Quart, Journ. of Micros. Soi, 





na, vol. ix. 1860, p 








snout tw oan eas ear os tc 
flagella, and two con. V1, villous tat." Soe 


the 
the rhizopod type is more common. in 
in! cre Amba 


is 

definitely characterised by peculiarities that te it from the 
two oes i |. The distinction between ‘ectosarc’ 
and ‘is clearly marked, so that the body approaches 
much more closely in its characters to an ordinary ‘cell’ composed 
of cell-wall and cell-contents. Tt is through the ‘endosare’ alone, 
N, that those coloured and granular particles are diffused, on 
which the hue and opacity of the body depend ; its central portion 
seems to have an almost watery consistence, the granular particles 
Lead to move quite freely upon one another with every change 
and 


shape of the body ; but its superficial jon is more viscid, 
graduates insensibly into the frmer sal of the ‘ectosarc.’ 
‘The ectosarc, EG, which is perfectly pellucid, forms an almost 
membranous investment to the endosare ; still it is not possessed of 
such tenacity as to oppose a solution of its continuity at any point, for 





substance of which their exterior is composed possesses 
tenacity. No movement of ules can be seen to take place along 


the surface of the pseu ; and when two of these organs come 
into_contact, hey eaioey show an} even to mutual 
cohesion, still less to fusion of their sul Sometimes the 


secms to be formed by the ectosare alone, but more 
commonly ea also are ze it, and an inate opie snc 
granules may seen to m what was previously the centre 
tithe ody int thie proteuded portion wien Shel aia 
rapid elongation ; whilst a like current may set towards the centre 
of the body from some other protrusion which is being withdrawn 
into it. It is in this manner that an Ameba moves from place to 
place, a protrusion like the finger of a glove being first formed, into 


+ This remarkable character has been stated by Professor Huxley in the following 
admirable wmtence: ‘Physically the ectosare kt dire rar po orycn eo 
somp- bubble, which, ‘though fluid, has ‘s certain a " 
particles to hold together and forma continuous sheet, but permite a robe meees 
into or through the, bubble without bursting it, the walls closing together, tO 
covering their continuity as soon ax the rod in drawn away.’ 


choke eng hey: ito the 
‘or in 
prnlavas. nnbbie separates ; 


a is' of Acti 
i i ee hy Grech and pees by him 
palustris (fig. 520), wl reads over the tom ot 
ae Vien Ray Heakadl GE indefinite form, 


hyaline ectosare 
contains such a multi- 


‘ 
r3 table matter at 

of the pool it ae blackish hue, 

in other situations it may be colourless. Besides the vacuoles 
there are seen in the endosare a great number of nucleus-like bodies, 





+ Prof, A. SM. Bdwands (U.S.A,) in Monthly Microre, Journ, vol. viii, 1879, pM 


670 MICROSCOPIC FORMS OF ANIMAL LIFE 


¢, ¢, and also many hyaline globular brilliant bodies, fj ; which are 
regarded by Greef as germs or swarm-spores developed from nucleoli 
set free within the general cavity of the body by the bursting of the 
nuclei. This creature during the active period of its life moves like 
an amoeba, either by general undulations of its surface, or by special 
pseudopodial extensions, d. After a time, however, its movements 
cease, and it looks as if dead ; but by the giving way of its ecto- 
sarc, a multitude of minute amecbiform lies break forth, each 
having its nucleus and contractile vesicle, These at first live as 









—Pelomyza palustris: A, an it eppeeet. when in ameboid 
}, portion more highly magnified, shor 






omare; b, one of the vacuoles of the endosare 5 
bably Bacteria) weattered through the endoware; dy 
sion of ectosure with endosare passing into it; ¢, ¢, nee 
hyaline bodies. 





Ameber, but afterwards pass into a resting state, assuming a spherical 
or oval shape, and then put forth flagella, by which they swim 
actively for a time ; later on, they probably settle down to develop 
themselves into the parental form. 

The Ameban like the Actinophryan type shows itself in the 
testaceous as well as in the naked form, the commonest examples 
of this being known under the names Arella and Diglugia. The 
body of the former is enclo in a ‘test’ composed of a horny 
membrane, apparently resembling in constitution the chitin which 
gives solidity to the integuments of insects ; it is usually discoidal 

















672 MICROSCOPIC FORMS OF ANIMAL LIFE 


aot analy Ail to’ toh a latesuniog pessoa oo 
not the test, intervening space 

by o clear Tiquid, and traversed by bands ands of . In the 
posterior part of the body is seen a clear nucleus, 
with a distinct dark nucleolus ; and in front of this are contractile 
vesicles, usually two in number! 

Coccokiths and Coccospheres.—This would ae ape ces) 
priate place for the description of certain 
very extensively diffused pone the deep-sea ct ee 
ing in eulnaen 
which ae considered as 
chalk in process of formation. 
It was in the specimens of 
this mud , brought up by the 
*Oyel Prarie pp. ba 
that fessor Huxle; 
found the Coccolithe Ge. son, 
ye 2 ee Dr. Wallich = 
1860 found aggregated it 
ve asses which he 


(on! Regarding the 
(a). in, 
nous matrix in which tuey 
were imbedded as anew: 
of the Monerozoa descril 
Haeckel, having the condition 
of an {indefinitely extend. 
= amodinm, Professor 
ux! posed to designate 
it by me name Bathybius, 
indicative of its habitat in 
the depths of the sea ; he 





Fra, bern empl: reecties with Ht - <i, cco ta 
tion a li 
Bathybius, with imbedded coccoliths, is given in oy ae 5 At 3 “hie 
observations made in in the ‘Challenger’ Batlemeneiog tes i 


not confirmed this view ; the supposed Bath; is 
precipitate, consi: of sulphate of lime, ‘owl in water 
to which strong spirit has been added. their nature, 
coceoliths and coceospheres are bodies of hiboeln intonen) since their 
occurrence in chalk and in very early limestones is an. additional link 
in the evidence of tlie similarity of the conditions under which they 
were formed to those at present prevailing on the sea-bed of the 
Atlantic and other oceans. Two distinet types are recognisable amon; 

the coceoliths, which Professor Huxley has designated reapecunelyt 
discolithe and eyatholiths, The former are round or oval dises, having 






+ See especially the recent admirable work of Professor Loidy on the fresh-water 
thizopods of the United States, 1840. It is to be ragretted that i aie anib's Gast 
and opportunities did not permit him to follow out the lite-histories of the many 
interesting forme which he has desoribed and figurod 





re sere ih need expan 4 
ae rite ween in Dag pet ‘riew, ae 1) ental al soxpuscl, i) 
‘tennsparent outer zone; 8 9, 

other ; MR pe ng ctan cd dene 
two faces. In either of these aspects they seem to be com of 
Ne concentric es nee (A, 6, 2,4) surrounding an oval thick-walled 
esl ooxpaele (*), in the centre of which isa clear space some- 
times divi into two, The zone (2) immediately surrounding 
poe central corpuscle is usually more or less distinctly granular, 
etconGs has an shane bead-like margin. nities peste 
outer zone (3) is generally clear, t, and structureless, 
but sometimes shows radiating strim, When viewed sidewise or 
cellansiy, however, the ‘cyatholiths’ are found to have a form 
somewhat, resembling that of w ebirt-ctud (figs. 2,2, 7). Each con- 
sists of a lower plate, shaped like a deep saucer or watch-glass ; of 
a smaller upper plate, which is sometimes flat, sometimes more or 
less concavo-conyex ; of the oval, thick-walled, flattened corpuscle, 


which connects these two plates together at their centres ; and of 
xx 


i 


Srorozoa, 
‘The term has been applied by Leuckart to a group of 


menal 
also belong. They are i i 


i 
g 
sine 
gest 
i 
a: 
=) 


small ‘gpores.” 

The Gregarinida lead a parasitic life, and often be met with 
in the intestinal canal or other cavities of worms, insects, de. 
and sometimes in that of higher animals, An individual 
essentially consists of a large single cell, more or less ovate 
in form, and sometimes attaining the length of teo- 
thirds of an inch? A sort of beak ce Bybee ea ee 
from one extremity ; and in some instances this is i with o 


in Actinophrys or in Amoha; and in this respect we must look 
Gunte a representing a decided advance in o1 5 Bang 
nourished upon the juices phos! for it by the digestive 
operations of the animel which it it has no need of any such 
apparatus for the introduction of solid particles into the interior of 
its body, as is provided in the pence the rbizopods and 
in tho oral cilia of the Tnfusoria. Within the cavity of coll, 


} Consult the memoir by Dr. I. Blanchard in Hull. Soe. Zool. Bronce, x. 
? See Prof. Ed, Van Beneden on Gregarina gigantea (found in the 

canal of the lobster) in Quart. Journ. Microsc. Soi. ms. vol. x: 1870, jx 51,and yok 

ai. p, 242, 





Fro. 521—Cyst af Monocyatie agilis, the Grognrinid of the earths 
(720 diame.) shoving ripe “uiinere pnd Complete abeance of 
Sexcpecina? peotepieers ia is opek  (aiber irafamoc Hag tansasian} 


which he has found to consist of a layer of contractile 
fi When the process of encystation commences we find that, 
whatever the original form of the body may be, it becomes globular, 
ceases to move, and becomes invested by a structureless ‘cyst,’ 
within which the substance of the body undergoes a singular change. 
The nucleus disappears, and the sarcodic mass breaks up into a 
series of globular particles, which gradually resolve themselves (ax 
shown at 4, ¢, d, ¢, fig. 525) into forms very like those of Vavicule, 
and a cyst more advanced, and greatly magnified, is shown in fig. 524. 
These ‘ navicolle' or ‘spores,’ as it is better to call them, are 
‘set free in time by the bursting of the capsule that incloses them ; and 

xx2 


SPOROZOA 677 


mapsule around them both ; the partition-walls between 
ies disappear ; and the substance’ of the two bodies 
mmpletely fused together. But as the products of this 
& the same a. thas of the ondinary encrsting ‘process, 
os no sufficient reason for regarding it, like the ‘conju- 
protophytes, as a true ive act. 

ccodia (fig. 526) are Sporozoa which look like minute ova, 
brachii peering korrserheabragt tear iat the young, 
from spores, are falciform in + moving about 
re able to fresh cells, They have bees, found 
helium of the intestine of various forms, and in the liver 
ates. Some parasites found in the blood, such as Drepani- 
trum, Lankester, may be migrating young. 

» imperfectly known Myzosporidia it may be said that 


es are the i dap ap andi) ‘ 
» bodies observed i others, and wrongl: 
‘a tie cases at the matte are sarcooystids which 
muscular fibre of mammals. 


Malia tdtenes of Brcleasoe to the Linnean Society for 1876 and 
noo 1 of ite Journal) on ‘ Recent Researches on some of the more 
em cof w teh hie A vilsce hes realy piel eee ee 
aling with the Rhizopoda and Sporosoa in Professor Blitschli’s edition of 
ween und Ordnu: des Thiorreichs,1880, and Professor Ray Lankester’s 
x%tozos,’ in the ninth edition of the Encyclopadia Britannica, 1886. 





CILIATE INFUSORIA 679 
is difficult to decide what is their relationship to other groups of 
*Vermes.’ Ne ing the wide zoblogical separation between 
those two kinds of it seems most suitable tole: pita 
of the ion with one FA 





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the food into the digestive cavity, This cavity is still 
0 wr, a8 in rhizopods, by the endosare of the eell ; but 
1 el cieapa pean Retr eonartediog the 
-particles are usually eat luring their passage down 
the esophagus, into minute pellets, each of which receives a special 
of firm protoplasm, constituting it a digestive vesicle 

531) ; and these go through a sort of circulation within the 


‘The ‘contractile vesicles,’ again, attain a much higher develop- 
ment in this and are sometimes in connection with a network 
of canals out in the ‘ectosarc’; while their rhythmical 
action resembles that of the circulatory and respiratory apparatus 
of higher animals. There is ample evidence, also, of the nee 
of a specially contractile modification of the lasmic substance, 
tie de action (though not the structure) of muscular fibre ; 
and the manner in which the movements of the active free-swimming 
Tnfusoria are directed, so as to avoid obstacles and find out passages, 


i 


a 


g 


MICROSCOPIC FORMS OF ANIMAL LIFE 


ge pene peels Meese 
Po Hi ich hs oe 
characterise the siercows systems of fer pene 
ppoiriehery emer twee + eal 
Before to the d “of the oiliate Tafoscria 
however, it will be of ad es tohiee tee nealae 
fogulte ood tia miclocial-=setalculocoudst ob Wea u 
of their structure and actions, are now ranked as areas 
whose ‘unicellular’ character there can be no reasonable ’ 
thie merpholotaly from 1 Ree aver cells, scareely distinguish- 
sBosptnloueely, 
eee very a ot any Vt 


in recent ‘not only by the ofa 
pie am comeun Tae 
= ‘the smallest li aa at 
16 
oeoensetita ng iat ei oe 
Senay Caleb 
relation to sponges. The er ape 7 
iicroscopists a8 occurring in and 
to ry perveenrtyer 


not by any definite mouth (or t opening in th n 
but through an eset 8 itself in some part of the 
region near the base of the flagellum. In some true Monadine 
neither nucleus nor contractile vesicle is » bat in 
the majority a nucleus can be clearly seen. “life-history of 
camalie simple Monadine: presenting themselves in infusions of 
decaying animal matter = ‘cod's head hae found the most: 
admirable Decrees 


penta material) has been studied with 
[ati nfrasieinntedbmeddn terror een og a 
forward by You min ( rich ier vergieteh. hed Be ig a8) tn in. 


a SEA ty an tant ny i 
Be Saeco baveeen ie ee 
Neciqua taeron nape ren 

ital ‘i os in soe 


‘and by the former alone in the life-histories of the 
ed rocestes as soon in even the lowest of 


‘all foreibl; insisted on Haeckel (* Zor : 
rnaseche SZ eitechr. A. 9a, i Wefepec Eye: ie hee 





maagiven by Professor Allman. Presidential Address to the Linnean Society in 
* The family Monadina ot Ehrenberg and Dajanlin consists of ot 
forms now known fa bet very yrs eget _ nature, many of therm | the: 


vegetable kingdom. 





0 ife-history. 
entire group, all is subservient to rapidity of multiplication ; and 
Shere ere-tae cuatbodsin-ehis chia i ected. "The fest nad com 


ee has a diameter of about the gy\jsth of an inch, 
has great case and grace, and relative power of movement. 
certain its history as it swims freely there sud- 
denly appears a constriction across its body, as in fig. 2 This is at 
panied Nain ent effort of the opposite flagella to 
er; the ence is a very rapid stretching 
aneck of sarcode between two halves of the body, as at fig. 3. 
‘This becomes longer, ax at 4, and attains the length of two flagella 
as at 5, when the two dividing halves approach and mutually dart 
from each other, snapping the connecting fibre of sarcode in the 
middle, so that two perfect forms are set free, as in 6 and 7. 
This, in the course of from two to three minutes, is once more 
begun and carried on in each half successively, so that there is an 
‘increase of the form by this means in rapid geometric ratio. 
But this is an exhaustive process vitally, for after a period vary- 
stag frome. sighe to ten days there always appears in the unaltered 
“unchanged field of observation normal j pee with a remarkable 
1 


See their successive papers in the reig Microsc. Journ. vol. x, 1878, 
be tvdeed} ‘vol. xi 1874, pp. 7, 60,97; vol. xii. 1874, p. 201; and vol. 5, 
p18; and Proceed. Toy! Soc. vol. xxvii, 1478, p. 892. But expecially for the latest 
resulte with recent objectives, Jowrn. Roy. Micro. Soc. vol. v. 1885, p. 177; 

‘vol, vii. p. 185; vol. viti. p. 177. 








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much more complex morphological . It is seen in its normal 
form in tig. 1, Tt has but one and, as we believe, om 
that account has a much more restricted of movement. It. 
is from the yqlgqth to the th rh beta oor Tn 


up, and becomes a knot of slightly moving AA iron as in 
fig. «; which remains in this state for from to twenty 
minutes, and then becomes dissociated, as in 9; 80 that we have 
here a complex form of aot linia pees gi rise to enormous 
numbers, because, although much smaller than the form in which 
they arose, they consume and assimilate food all and are 
simply heey in their peal and so rapidly reach the normal 
ize, when they each enter upon a similar: 

Eiicesicargesany dre St jemeiabiee 
augurate distinctly genetic processes. A form like fig. 19, C, appears, 


larger than the normal form, and always mottled in 

est the flagellum. These forms rapidly attached 

normal forms, as seen in fig. 11, which resulted in a i 

twoas they swam together, until ‘either was melted into 

a still sac, shown in fig. 12, resulted, ' 
‘This remained from thirty to thirty-six hours 

but at the expiration of that time it burst, as seen it 

poured out an enormously diffusive fluid, which as it 


surrounding waterappeared like adonser fluid, eee 
one of Joie tunic ; but nospores were at this stage at: 


E 
Ef 


Bt 
Hi 


) 


Plate XIII. 


a 
ot 


ae 





WH Dallinger del ad nat Huth, Lith? Eat 
LIFE HISTORIES OF SAPROPHYTES. 


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advath. This monad swims 
ich are graceful and varied, 
lla, which ean not only 
reverse its course or check 
swimming movement, a very 
curious petite Bis net enithet 
composing organic matter fusion is ‘ing up, process 
inte ing apparently assisted by it. nat posteriol 
and coil into a spiral, and the body then 
forwards and upwards, until the anchored flagella st: 
the falls forward to its horizontal position, to 

‘drawn back by the spiral coiling of the anchored 
iplies by longitudinal fission, the first stage of 
splitting of the anterior flagellum into two (fig. 2, 4, 4), 
anda movementof the nucleus (¢) the centre. In the course 
of from thirty to sixty seconds the fission extends down the neck (tig. 
3, @) ; a line of division is also seen at the posterior end (c), and the 
) shows an incipient cleavage. In a few seconds the 
-line runs through the whole length of the body, the separa- 
widest posteriorly (fig. 4,@); and in from one to four 
minutes Himes becomes almost complete (fig. 5), the posterior 
of the body, with the two halves (@ and 6) of the original nucleus, 
now quite disconnected, though the anterior parts are still 
held together by « transverse band of sarcode, as seen in fig. 6, which 
continues to rapidly elongate, as in fig. 7, and becomes the length of 
two side flagella, asin fig. 8. ‘The forms then approach and rapidly 
recede from each other, snapping the cord, as in figs. 9 and 10. In 
this way tro forms exist in of one; and each of these almost 


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ace 
lost, the nuclei ¥: resultant it an amesboid mass 
fee nine and “still * 
condition represented in fig. 14, a. This ix a cyst filled with 
ductive icles of such extraordinary minuteness that, 
emitted from the ends of the oyst (fig. 15, a) see teehee 
Se ere a ee tea ee under an amplification 
of 5000 diameters, wi eh edn" tae pal en co 


ar 16, 17, 18 0 ‘hand win thw foneenter 
dime mis 16, 1 1 ae ) in sre 
‘atonal (ig =id), Gaal movements: 
iter ag eck tik a Roan od shows itself about: 
half an hour more the ema swimming action begins. About 
four hours after the escape of its germ from the sac, the monad 
acquires its characteristic (fig. 21), though still onl; the 
aaa! nt ; io er de: attains in another hour, and the 
process of mi lication ion, as already described, commences 
very soon cholera er "There ‘can be no reasonable doubt that the 
‘conjugation ' of two individuals, followed by the transformation of 
eae rare bodies into a sac ee with Tenroauol peas is bed 

‘as in protophytes) in the lightof a true generative 

and i it enone oH balk Bhs iitetten sexual di 


here marked by the different states of the two ee 
‘There is every reason to believe that the entire [) oe 
has thus been elucidated ; and it will now be s 

principal diversities observed by Messrs. 


the life-oyeles of the other eh forms 
sored flagellate or aye "ona a he same | ‘ear ai 
Kent with the Polytoma w Freer yon 
remarkable peculiarities in its mode of 
fission extends only to the protoplasmic pli cr ec fond 


SAPROPHYTIC LIFE-HISTORIES 685, 


































entire ; and by a repetition of the process, as many as six- 
jents, each attaining the likeness of the parent, are seen thus. 
ir flagella protruding through the general investment. 
pund state being supposed by Ehrenberg to be the normal 
ned it accordingly. But the parent-cyst soon bursts, 
the contained ‘macro-spores,’ which swim about freely, 
ttain the size of the parent. Again, the posterior part 
By of certain individuals shows an accumulation of granular 
giving to that region a roughened acorn-cup-like aspect ; 
of the projection, while the creature is actively swimming 
‘water, sets free a multitude of indefinitely shaped granular 
within each of which a minute bacterium-like corpuscle 
d; and this, on its release, acquires in a few hours the 
m of the original monad. This process seems analogous 
elopment of ‘micro-spores’ among protophytes by the 
ng up of the protoplasm. It is, like the previous pro- 
xual or gonidial, the true generative process consisting 
‘4m the preceding cases, in the ‘conjugation’ of two indi- 
‘with the usual results. 
ed monad (Heteromita uncinata, Kent) is another bi- 
form, usually ovate with one end pointed, and from 355th. 
h of an inch in length, being distinguished from the pre- 
the peculiar character of its flagella, of which the one that 
D d is not more than half the length of the body, and 
pently hooked, while the other, whose length is about twice 
B the body, is directed backwards, flowing in graceful curves. 
ftion consists of a succession of springs or jerks rapidly follow- 
other, which seems produced by the action of the hooked 
p. Multiplication takes place by transverse fission, and con- 
} uninterruptedly for severaldays. A difference then becomes 
ible between larger and smaller individuals, the former 
farther distinguished by the presence of what seems to be a 
etile vesicle in the anterior part of the body. Conjugation 
between one of the larger and one of the smaller forms, the 
‘being, as it were, absorbed into the body of the larger ; and. 
alting product is a spherical cyst, which soon begins to 
@ cleavage-process in its interior. This continues until the 
of its sarcodic substance is subdivided into minute oval 
which are set free by the rupture of the cyst, and of 
th each is usually furnished with a single flagellum, by whose 
lug movement it swims freely. These germs speedily attain the 
and form of the parent, and then begin to multiply by transverse 
tw, thus completing the ‘ genetic’ cycle. 
calycine monad of the same observers (Tetramitis rostratus, 
ty) bas a length of from g!,th to y,'soth of an inch, and a 
body tapering backwards to a point. Its four flagella 
th constitute its generic distinction) arise nearly together from 
flattened front of the body, and its swimming movement is a 
wfol gliding. Near the base of the flagella are a pair of contractile 
des, and further behind is a large nucleus, Multiplication takes 
seby longitudinal fission, which is preceded by a change toa semi- 








generation,’ or abiogenesis ; since it shows 
hat germs capable of surviving desiccation may be every wherediffused 
through the air, and may, on account of their extreme minuteness 
(as they certainly do not exceed gyaleguth of an inch in | 
altogether escape the a nee seratiny and the sia 
cleansing processes ; while their extraordinary resisting 
heat: will even these germs from being killed, idher by boiling, ue 
by dry-heating up to even 300° Fabr.t 
Beyond these facts others of some importance, as well as a new 


1 Desoriptions of th i ‘used by Messrs. 
niece te ah a 
wol. xv. 1876, p, 165; and Proceed. oy. Soe, vol. xxvii. 1878, p. S48. 


juestion of * spontaneous 


THE MONAD. NUCLEUS WITH RECENT LENSES 687 


cP pered. Buri special character, have been discovered 
Snell ted etesaeent lee oe 


investigation. 
easily accessible proof of this is given in the work done by 
raponithe nuclousof the nucleated forms of these monads. 
t the facts, we may recall the part taken in the 
the form last described (Dallingeria Drysdali). It 
n by reference that it to us that the nucleus fol- 
processes inaugurated by the somatic sarcode. That in fact 
i participating in the set of Sesion: This is all that 
de out tren the very lenses originally employed. 
‘by the emp! leyment of « yyth ach and. yh ineh homo- 
NA 1150 by Powell Lealand, and an apochromatic 
pinch NA. 1:40 Oty te sane Fn and also by the use of 
etifol $ mm. and 2 mm. N.A. 1-40 of “eles (apechromatic), 
ibe ‘seen with comparative ease that it is in the nucleus that 
ae the be body ore originated. 
astudy of Plate XIV. Fig. 1, A, 
= the neclen of ae form drawn at fig. 1, E, Plate 
In long diameter it is of an aver len, aoth of an 
but instead of being darkly refreetive: object se seen with 
tives used twelve years ago, it is with the present lenses, 
n chromatic and spherical aberration, a body in the monad 
no process of change, an oval globule with a complicated 
involution throughout its substances, as seen in fig. 6, A, 
XIV. Butdirectly the process of fission is to be inaugurated, 
d not wait to see its first action in the splitting of the 
as in fig. 2, E, Plate XIII, ; for by observing the nucleus 
over, before any change hes” begu: in_in the body- substance, 
plexus i in the nucleus has condensed itself on either side of 
as in fig. 1,5, A, Plate XIV. A clear space is left at c, 
change has taken place in the body-sarcode, «, a, a. Bi 
By an incision takes place in the nucleus, as at d, fi 
‘immediately followed by the incision f in the body- 
he process 5008 © goes on simultaneously in nucleus and body, as in 
5 ivision of the nucleus is completely effected, and the 
jeeverance ‘of the body follows. 
tt as soon as the nucleus is divided, the plexus, which has been 
as in fig. 3, condensed over part of each dividing 
st once distributes itself evenly again, as in fig. 6, A, and re- 
8 s0 until another change is inaugurated in the form to which 
meleus belongs. 
1 Journ, of Royat Micros. Soc. vol. v. 





amesboid. Teepe as an amebe, but 
retaining traces of their primal form. In this state two of them 
blend, and as a result a sac of spore is formed from which a new 
generation arises. 

We could with the old objectives determine nothing more than 
the fact that the amo:boid form had ; but now it is to 
show that the ee aed body see em patie gintioll is 

ing change upon w! amecboid state is certain to supervene, 
* Sie qensooe ane in the growth of the germ, It attains 
‘a certain size in growth, then there is an arrest of all 


th 
velopment. Fig. 1, B, Plate XTV, shows the condition of the nuclous 
when there ix an apparent pause in its growth, 2 shows the 
same nucleus after about forty minutes of external 
like formation having filled its substance. 

‘The nucleus remains thus in the mature body of 
until fission is to be inaugurated, when the change 
followed by the changes and deeper division seen 
7, and 8, which, after the state of She 2c aN eS ae 
been reached, is shared in by initiation of division in the sul 
Si ene ale onne Aaryokinesis takes place in the 

t thus appears that a form of inesia 
nucleus of even such lowly forms as these, and that it is the nucleus 
that is the seat of their intensest vitality. 

A large series of more complex forms of flagellate Tnfusorin 
has been brought to our knowledge by the researches of the late 




















FLAGELLATA 689. 


James-Clark (U.S.A.),! followed by those of Stein, Saville 
Bergh. In some of these a sort of collar-like extension of. 
tobe the protoplasmic ectosarc proceeds from theanterior 
of the body (fig. 527, cl), forming a kind of funnel, from the 
which the flagellum arises ; and by its vibrations a cur- 
ced within the funnel, which brings down food-particles 
disc ’ that surrounds its origin where the ectosarc seems 
that which envelops the rest of the body. Towards the 
}the collar a nucleus (n) is seen; while near the posterior 
jon of the body is a single or double contractile vesicle (cv). 
is attached by a pedicle proceeding from its posterior 
, which also seems to be a prolongation of the ectosarc. 
jcules multiply by longitudinal fission ; and this, in 

(as in the genus Monosiga), proceeds to the extent of a 
separation of the two bodies, which henceforth, as in the 
Monddina, « 


themselves, 

arborescent 

like those of Single votid of Cadusiys wutellatas cl, 
are pro- collar; », nucleus; cv, double contractile vesicle. 








In another group a structureless and very transparent horny 
closely resembling in miniature the polype-cell of a Cumpanu- 
forms itself round the body of the monad, which can retract 
M into the bottom of it; and in the genus Sd/pinyrea both 
Rand collar are present. In some forms of this group multi- 
seems to take place, not by fission, but hy vemmation ; 

fe among hydroid polypes, the gemma: may vither detach 
fmelves and. live independently, or may remain in connection 
Bitheir parent-stocks, forming composite fabrics, in some of which 
Qalyces follow one another in linear series, whilst in others they 








"Nee hin memoira in Ann, Nat. Hist. wer. 3, vol. xviii, 1466; i/.i. sex. 1. vole i. 
h AN71; and vol. ix. 1672, 
"hee hin Manual of the Infuacria, 1680-82, 2 vols, and 1 vol. of plates. 


yY 





690 MICROSCOPIC FORMS OF ANIMAL LIFE 


take on a ramifying arrangement. While some of these composite 
organisms are sedentary, others, as Dinobryon, are free-swimming. 
Two solitary flagellate forms, Anthophyse and Anisonema, may 
be specially noticed ss presenting several interesting points of 
resemblance to the peculiar type next to be described, the most 
noticeable being the presence of a distinct mouth and the 
of two different motor organs—one a comparatively stout and stiff’ 
bristle, of uniform diameter throughout, which moves by oceasional 
jerks, and the other a very delicate tapering flagellum, which is 
in constant vibratory motion. Tf, as appears from the recent observa- 
tions of Biitschli, the well-known Astasia—of which one species has 
a blood-red colour, and sometimes multiplies to such an extent as 
to tinge the water of the ponds it inhabits—hasa true mouth for the 








Fro, 628.—Codosiga umbellata: Colony-atock, springing from single 
pedicel tripartitely branche 





teception of its food, it must be regarded as an animal, and sepa- 
rated from the Euglena (with which it has been generally associated), 
the latter being pretty certainly a plant belonging to the sune 
group as Folvor,! 

an be no longerany doubt that the well-known Voetiluan 
to which is attributable the dijfwaed luminosity that fre- 
sents itself in British seas—is to be regarded ns a gigantic 
the ‘unicellular’ £Yegel/ata, This animal, which is of spher- 
Al form, and has an average diameter of about gyth of an inch, 
is just large enough to be discerned by the naked eye when the water 
in'which it may be swimming is contained in w glass jar held up to 
























1 Seo the memoir by Prof. Biitschll in Ze 
of which an abridgmont (with plate) ix give 
1879, p. 08. 





chrift f. Wisenseh. Lo 
Quart. Journ. Micros, 








NOcTILUCA 691 


its tail-like appendage, whose length about equals 
which serves as an instrument of locomotion, 
ahand-magnifier. The form of Voctiluca is 

so compressed that while on one aspect (fig. 
projected on a is nearly circular, it 
aspect (B) at right angles to this. Along 

a4 meridional groove, resembling that of a 

into a deep depression of the sar- 

the shallower commencement of 


t 
mass proceeding to’ superficial ris 
‘2, nucleus, (Magnified shoud ainsi BT 

cle : this is of firmer consistence than the rest of the body, 
somewhat the appearance of a rod imbedded in its walls. 
suth opens into a short esophagus, which leads directly down 
great central protoplasmic mass; on the side of this canal, 
*« from the tentacle, is a firm ridge that forms a tooth-like 
tion into its cavity ; whilst from its floor there arises a long 


fargan bare, termed tentacle i commonly designated lapeliums while 
the flagellum is spoken of by most of those wlio have recognised 
silium. ‘The Author agroes with M. Robin in considering the former organ, 
vemarkable resemblance to & single fibrilla of strinted musclo an 

fo Noetilued ani the later asthe true homologue of the Gagellam, of 

inta, It is eurions that several observers have been unable to div. 


cilium, which was first noticed by Krohn. Professor Huxley sought 
individuals without success; and out of the great number which 
he did not get a clear view PASSA Site Va ae 
YY 











Fro, 551.—Phir of digestive vesicles of Noctétuea lying in course of exten- 
son of central protoplaamio mans, «to form peripheral reticulation, 
4, aud containing remains of Algw. (Magnified 440 diamoters,) 


shows an alternation of ght and dark spaces, in every t 
resembling those of striated muscular fibre, except that the clear 
epee But when looked at in profile, it is seen 
preeee cer aiaren Dane And she. spors] ikea isa lay me 
granular protoplasm. ten! over to’ 
mouth about five times in a minute, and Miata welt still more 
slowly, the middle portion ag first, while the point approaches 
the base, so as to form a sort of loop, which presently straightens. 
It Seeaetetie that the contraction of the substance forming the 
dark tees the bending of the filament; whilst, when 
this Sa filament is straightened again by the elasticity of the 
ee The tenon transparence of Voctiluca renders it a particularly 
favourable subject for the study of the phenomena of phosphorescence. 
When the of the sea is rendered luminous by the general 
diffusion of Vootilweer, they may be obtained by the tow-net in un- 
Limited quantities ; and when transferred into a jar of sea-water, 
son rise to the surface, where they form a thick stratum, The 
agitation of the jar in the dark causes an instant emission of 













inning in the en! 
halves of the nucleus, 
of non-sexual 
of many proto) 
The tentacle fi 


¢ mouth is subsequently formed, and the cle a ae , 
flagellum ai Sa make their appearance, al “conjuga- 
tion’ has also been observed, alike in ordinary Noctilwom and in their 
closed or encysted forms, which soems to be sexual in its nature. 
‘Two individuals, applying their oral surfaces to each other, adhere 
closely together, and their nuclei become connected by a’ of 
protoplasmic substance, ‘The tentacles are thrown off, the two 

gradually conlesce, and the two nuclei fuse into one. The whole 


foe occupies about five or six hours, but its results have not 
lowed out.! 


i 


* Noetilwen has beon the subject of numerous preci! which the 


are the moxt recent: Cienkowski, Arch, f. Micros. Amat, Bd. viv 181, aw 
Ba. ix. 1873, p, 47; Allman, Quart. Journ. Micros. Sei. u.% vol. 2 ‘827; 
Robin, Journ. de CAnat. ef de Physiol. tom. xiv. Dp 586; veh. he 
Phyviol. eér. ii. tom. ¥. 178, po 4162 Stein, Der der | r 
iti. 2, 1883; and Biitschli, Morphol. Jahrbuch, x. P, $20, For the 

which it and Lepfodiscus (Hertwig) aro the representatives, Ray Lankerter 


geuted the name Khynchoflagellata, 





DINOFLAGELLATA 695 
must 


by Professor Al in 1854 was in such tities that 
iti a brown colour to the water of some of nap pane 
in ix Park, Dublin, this colour being sometimes ly 
and sometimes showing itself more deeply in dense clouds, 
patton fosas K cow asta yards tO up wardn cl a hundred. 





Fro, 682.—Periifinium wberrinium > A, B, tront und back views ; 
©, eneystad stags; D, duplicative subdivinion. 


has been rarely 
observed ; but a large nucleus, sometimes oval and sometimes horse- 

seems always present. The Peridinia multiply by 
transverse carne. 532, D), which commences in the subdivision 
of the nucleus, then shows itself externally in a constriction of 
the ungrooved hemisphere, parallel to the equatorial furrow. They 
pass into a ean condition, subsiding towards the bottom of the 
water, and the loricated forms appear to throw off their envelopes. 
‘There is reason to believe that conjugation obtains in certain cases : 
Glenodinium cinctum has been observed by Professor Askenasy to 
copulate, but the development of the zygote, ax the product of copu~ 
lation may be called, has not yet been worked out. Some of the 
Peridinia are found in sea-water, but the most remarkable marine 
forms of the cilio-flagellate group belong to the genus Ceratinm (fig. 
533), in which the cuirass extends itself into long horny appendages. 

4 Or, more correctly, Dinomastigophora, 








696 MICROSCOPIC FORMS OF ANIMAL LIFE 


Tn the Ceratini tripos (1) there are three of these appendages ; two 
of them curved, proceeding from the anterior portion of the cuirass, 
and the third, which is straight or nearly so, from its terior 
portion. They are all more or less jagged or spinous. In Ceratinm 
furca (2) the two anterior horns are prolonged straight forwards, 
one of them being always longer than the other ; whilst the posterior 
is prolonged straight backwards. The anterior and posterior halves 
of the cuirass are separated by a ciliated furrow, from one point of 
which the flagellum arises; and at the origin of this is a deep 
depression into which the flagellum may be completely and suddenly 
withdrawn, The Author has found the Ceratiun tripos extremely 





E20. £291, Ceratine tripon; 2, Ceratinin fierca. 


gbundant in Lamlash Bay, Arran, where it constitutes a Principal 
article of the food of the Antedons that inhabit its bottom. 
Suctoria—The suctorial Infu constitute a well-marked 
group, all belonging to one family, Acinetina, the nature of which 
has been until recently much misunderstood, chiefly on account of 
the parasitism of their habit, Like the typical Mfonadina, they are 
closed cells, each having its nucleus and contractile vesicle; but 
instead of freely swimming through the water, they attach therm- 
selyes by flexible peduncles, sometimes to the stems of Vorticellinm, 
but also to filamentous Algw, stems of zodphytes, or to the bodies 
of larger animals. Their nutriment is obtained through delicate 



















1 Seo Allman in Quart, Mfieros, Journ. vol, iii. 1856, p. 94; 11, Jamos-Clark in 
lim: Nat. Hist, ser. fi vol. xvi. 1960, p. 420; wna Bergh, Morphol. Jarbuehy vik 
AMD, p. 177 





ACINETINA 607 


tubular extensions of the ectosarc, which act as suctorial tentacles 
(fig. 534), the free extremity of ‘each being dilated into a little 
knob, which flattens out into a button-like disc when it is applied 
to a food-particle. Free-swimming Infusoria are captured by these 
organs, of which several quickly bend over towards the one which 
was at first touched, so as firmly to secure the prey ; and when 
several have thus attached themselves, the movements of the 
imprisoned animal become feebler, and at last cease altogether, its 

ly being drawn nearer to that of its captor, Instead, however, 
of being received into its interior like the prey of Actinophrys, the 

ured animaleule remains on the outside, but yields up its soft 
substance to the suctorial power of its victor. As soon as the suck- 














Fro, 53 v tion of Podophrya 
guadripartita; 9, formation of embryov by enlargement and sab. 
jirision of the nuiclons; 4, ordinary form of the same; 4, Porlo- 





phy elongata. 





ing dise has worked its way through the envelope of the b 
which it has attached itself, a very rapid stream, indicated by the 

wales it carries, sets along the tube, and pours itself into the 
interior of the Acineta-body. Solid particles are not rec through 
these suctorial tentacles, so that the Acinetine cannot be fed with 
indigo or carmine ; but, so far as can be ascertained by observation 
of what goes on within their bodies, there is a general protoplasmic 
eyelowia without the formation of any special ‘digestive vesicles.” 
‘The ordinary forms of this group are ranked under the two genera 
Avineta and Podophrya, which are chiefly distinguished by the 
presence of a firm envelope or /orica in the former, while the body 
of the latter is naked. In one curious form, the Ophryodendron, the 
suckers are borne in a brush-like expansion on a long retractile 




















CILIATA 699 

formed, and they gradual the characteristic 

form of spars & “. jugation ’ has been 
observed in this type, the body of one individual down 80 
as to its free surface to the part of another, 
with it becomes fused (fig. 534, 1) ; but: this always 


§ Ed ereS 
tee 
EoECESSLE3 
reed 
ruliee 
las 
ee "3 #84 
ag 
pete 
tie 
Hie 


their stroke is made, can be clearly seen. Their action has 
observed to continue for many hours, or even days, after the 
the body at ce As cilia are aoe confined eae 
zodphytes, but give motion to the zodspores man} 

protophytes, and also clothe the free internal surfaces of Dereact 
ratory and other passages in all the higher animals, including man 
(our own experience thus assuring us that their action takes place, 
only without any exercise of will, but even without conscious- 
nésa), itis clear that to regard animalcules as possessing « ‘ voluntary” 
control over the action of their cilia is altogether unscientific. 

In the ciliated Infusoria, the differentiation of the sarcodic sub- 
stance into ‘ectogare’ or cell-wall, and ‘ endosare’ or cell-contents, 


A The Acinetina were described both Ehrenberg anil Dujardin; but the fret 
fall, ‘of their peculiar organisation: ke given by Stein in ‘hin Organismus der 
fereden. Mitel, homer, hy their paraile tabi, Stein oignaly oy 
them % it u ‘itional stages: 
Nethediboa an eet alata Lafseday this doctten, be ie 


perry Much information as to this geoup will also be found in the 
sur les Infusoires et le Riicoposies of MM. Claparidle and Lach- 


HT 
ga 


g 





mph only by a stalk 
either to project itself 
interior, In the marine forms known as Dictocysta and C 
saccade Eerste dedherepcctirg ny agri 
shell, usual |-shaped or jot-shay which bears so strong 
a Rael to the shells of many Rantolore mis- 
taken for them. The form of the body i 


i 


characteristic shape, which is only di 
when the animaleule is subjected to Noa from without, or 

its cavity has been distended by the priate of any substance 
above the ordinary size, The cilia and mobile appendages of 








| 


‘condensed 
protoplasm, including minute ‘tri- 


ae 
au 
il 


| 
4 j 
Fad 

Bes 


tt 
retell 
ane 
ae Ht 
if ? [EE 


u 
54 
cy 
i 
Eb 
Ee 
a2 
a 


ith 
Egiree 
ie 
gl 


in 

the interior of their bodies, In some their vibration is constant, 
whilst in others it is only occasional, The modes of movement 
which infusory animalcules execute means of these instra- 
ments ave extremely varied and remarkable. Some propel them- 
selves directly forwards, with « velocity which appears, when highly 
magnified, like that of an arrow, so that the eye can scarcely follow 
; whilst others drag their bodies slowly along liken leech. Some 
attach themselves by one of their long filaments toa fixed point, and 
revolve around it with great rapidity, whilst others move by undu- 
lations, cae ‘or successive gyrations : in short, there is scarcely any 
kind imal movement which they do not exhibit. But there 
‘are cases in which the locomotive filaments have a bristle-like firm- 
ness, and, instead of keeping themselves in rupid vibration, are moved 

pga tte meettihogy, ot! the Vertlaliie oe Biitechl, Morphol. Jahr af, 
B® 


i 











702 MICROSCOPIC FORMS OF ANIMAL LIFE 


(like the spines of Echini) by the contraction of the nt from 
Se ee iunn orecnaeaene nim do riccre'd 
their means over a solid surface, as we see in 


tynceus is Py Chilodon and Nassula, again, the mouth 
iol wih Piities at pica folds, looking like bristles, 


istle-like bodies which project in some of them from the neighbour- 
hood of the mouth, and in Stentor from various parts of the surface, 
‘The red spots seen in many Jnfusoria, which have been designated 


protophytes. R. Hertwig, who seems-to have 
Rimself against the strictures of Professor Vi has a 
vorticellid—Erythropsis ayilia—as having a a which 
cannot but be regarded as a rudimentary: iq whe 
thinks that Lrythropsis is an acinetan, found « similar form with o 
similar eye near Madeira ; and Harker has observed that if light be 
allowed to fall on a part only of » colony of i versatile all 
the members soon congregate vo the illuminated 
The interior of the body does not always seem to consist of o 
1 The term ‘ ongans of fouse' Explies a eonseionsmess of lespressions, with while 


it is difficult to conceive that mnicellular Infusoria can be endowed. ‘The component 
cells of the human body do their work without themselves knowing ft. 





ae Riess nop msl escent them in size (f Aba z i 
when ve recently sw: since 

ey, eileen res haba cegreca ai 
not feed by any means i. s) kinds of 


indiscriminately, since particular 
are by particular kinds of aliment; the crushed 
and eggs of Entomostraca, for example, are so voraciously 
consumed by the Coleps that its body is sometimes quite altered in 
shape by the distension. This circumstance, however, by no means 


that such creatures possess a sense of taste wer of 
inate selection ; for many instances might be cited mm which 
actions of the like apparently conscious nature are with- 
out any such ‘The ordi: of feeding, as well as 
the nature and direction of the ci currents, may be is 
by ae the water containing the animalcules a few 
‘or carmine, may be seen to be carried by 


the ciliary vortex into the mouth, and their passage may be traced 
for a little distance down a short (usually ciliated) asophagus. 
There they commonly become aggregated together, so as to form a 
little pellet of nearly globular form ; and this, when it has attained 
‘the size of the hollow within which it is moulded, seems to receive 
an investment of firm sarcodic substance, resembling the ‘ digestive 
icles’ of Noctiluca, and to be then projected into the softer 
endosare of the interior of the cell, its place in the i 


i 


esophagus beit 
ena Aaa Lore oc atinanrey | la (This vmouldings 
however, no means universal, aggregations of coloured 
particles @ bodies of Infusoria being often destitute of any 


regularity of form.) A succession of such pellets being thus intro- 
duced into the cell-cayity, a kind of circulation is seen to take place 
in its interior, those that first entered making their way out after 
time (first yielding up their nutritive materials), generally by a 
distinct anal orifice, but sometimes by the mouth. When the 
pellets are thus moving round the body of the animalcule, two of 
them sometimes appear to become fused together, so that they 
obviously cannot have been separated by any tirm membranous in- 
vestment. When the animalcule has not taken food for some time, 
* vacuoles,’ or clear spaces, extremely variable both in size and 
number, filled only with a very transparent fluid, are often seen in 
its pote ; and their fluid sometimes shows a tinge of colour, 
which seems to be due to the solution of some of the vegetable 
chlorophyll upon which the animalcule may have fed last. 


> 





SUBDIVISION OF INFUSORIA 705 


ch of these animalcules may spring (by a repetition of the 
)) from one base. In ella pring (by of the same family 
structures are produced resembling that of Codosiga 
yy the like process of continuous subdivision. Another 
it of this mode of multiplication presents itself in the 
dina, masses of individuals which separately resemble 





Fro. 688.—Sexual (?) reproduction of Infusoria. 


a Vorticellina being found imbedded in a gelatinous substance 
reenish colour, sometimes adherent and sometimes free. These 
4, which may attain the diameter of four or five inches, present 
vetrong general resemblance to a mass of Nostoc, or even of 

wn, as to have been mistaken for such ; but they simply 
fom the fact. that the multitude of individuals produced by 
tition of the process of self-division remain connected with 

Zz 





LIFE-HISTORY OF INFUSORIA yo7 


era erent rrewan ta tho borin OLED into the ‘still’ 
vital activity. to the formation of the 
pl the movements of the animaloule ish in gray ane 


(fig. 540, A). A new wreath of cilia, however, is d near 
the base, and in this condition the animal detaches itself from its 
y wims freely for a short time, soon however, into 


animal can be distinguished. Even after the completion of the cyst, 
however, the contained animalcule may often be observed to move 
freely within it, and may sometimes be caused to come forth from 
its prison by the mere application of warmth and moisture. In the 
simplest form of the ‘encysting process,’ indeed, the animalcule 
ce oe ” quiescent pes Ye is of its 

; so that, however long may be the duration of its imprison- 
er ee nt cepneal sain teas form or con- 
dition. But in other i 


then caren ae wreath 
an/l multiplies by tranverse fission ; half fixes itself by 
the end on which the mouth is situated, a short stem becomes de- 
eloped, and the cilia-wreath disappears. A new mouth and cilia- 
wreath then form at the free extremity, and the th of the stem 
ey the alien into the true yorticellan cael Tn 
» again, the ‘ encysting process’ aj 8 subservient 
to a like of Canela tre ely 14 strhnas from the 
eyst differing in many res; from that of the animaleule which 
became encysted. According to M. Jules Haime, by whom this 
‘was very carefully studied,* the form to be considered as the 
Jarval one is that shown in fig. 541, A, E, which has been described 
Professor Ehrenberg under the name of Oxytricha. This possesses 
narrow, flattened body, furnished with cilia along the greater 
of both and having also at its two extremities a set of 
and stronger hair-like filaments ; and its mouth, which is an 
oblique slit on right-hand side of its fore-part, has a fringe of 
tminute cilia on each lip. Through this mouth large particles are not 
unfrequently swallowed, which are seen lying in the midst of the 
wor Dutersuchungen an Vorticetla nebutifern, quoted by Professor Allman, 
* Annales dee Sel. Nat, sor. ili. tome xix, 1868, p. 100. 


ii 


zz2 





REPRODUCTION OF INFUSORLA 7o9° 
within it cavity (M)., Th The body tere Cae rapes 
ie ha ; if m 
that in which it it 


yee 





ae 
te 


Eo their ordinary condition of activity cannot be dried 
up without loss of life. cain tity ty cote dd 


scsi in jun wih th xray ay ity of multipli- 
cation of these animaleules, there seems no sate a 
for the universality of their diffusion. iy esta ge 
fact that wherever decaying organic matter exists ina state, 


of Infusoria aro everywhere floating about in the air, ready to de- 
themselves wherever the ay ropriate conditions are presented ; 
all our knowledge of their history seems further to justify the 
Totiet that (in some instances, at least) the same germs may devolop 
themselves eats ® succession of forms so different as to have been 
seeaednn tinct specific or even generic ty 
ery im) t advance was, ccooet tanave been made in 
thi direction the asserted discovery of M, Balbiani! that a true 
of sexual generation occurs among Infusorin, his observa. 
tions having led him to the conclusion that male and female organs 
‘are combined in each individual of the numerous genera he has 
vexamined, but that the congress of two individuals is necessary for 
+ See his ‘ Recherches sur lex Phénomtnes sexuels des Infusoires’ in Dr. Brown- 


ieee sonra ae te Ey i¢ for 1681. An abstract of theas researches is 
in the Quart, Jowrn, of Micros, Sci. for July and October 1863, 








excretory 
middle of the length of the into the buecal 
individual also contains a seminal capsule, 4, 


themselves (as it were) into a bundle of filaments, are shown in. 
6-10, Inthe surface of the ovary, a, is seen to present 
“appearance, which is occasioned by the commencement 
ena into Eline ova; while het seminal is rs 
undergone division into two or secondary capsules, 

Pert vata bundle of spermatozoa now straightened ’ 
division takes place by the elongation of the into 


re ted in 11, and by the i 

whilst the extremities enlarge, ‘the farther 
effected by the ito oe Eau 
fission. In a, which represents one of the individuals r 
jugation, the four seminal capsules, 4, 6, are 
elongated in preparation for another subdivision ; 
a, a, has begun, as it were, to unroll itself, and to 


li 


LRT 
felt 


il 


if 
Hi 


1 


REPRODUCTION OF INFUSORLA vir 


seein ciate 
the ‘of the seminal of aay 


the from the these being now seen 
of witherii Fhally ne, pha Smear 
three days after com) of the jugation, are seen four 
OVA, 0, 0, 0, 0, the connecting tube, m, m; whilst 
ve now altogether disappeared. In ig, 
tages 


in size, and becomes more and more opaque from the increase of its 
ree contents (14, 15, 16), forming the ‘yitellus’ or yolk, in 
midst of which is seen the clear ‘germinal vesicle,’ whi 


(17). The germinal vesicle is subsequently concealed (18) by the 
‘increase in the quantity and opacity of the vitelline granules, The 
fertilised ova seem to be expelled by the gradual shortening of the 
tube that contains them ; and this shortening also pts ese ce 
the scattered fragments of the granular substance of original 
ovarium, so as to form a mass resembling that shown in 1, a, by 
ee 
juced. ry recently rein’ 
ui ienation fa the infcsoris : he finds that the nucleolus of each 
becomes a striated spindle, and approaches the nucleolus of the 
other cell; the two touch and finally fuse, thereby effecting an 
intermixture of the different germ-plasmas. If this be the correct 
manner of interpreting the phenomenon, it is clearly comparable to 
sexual reproduction of multicellular animals, 
There can be no doubt as to the occurrence of ‘conjugation’ 
pee ciliated Infusoria ; and this not only in the free-swimmi: 
in the attached forms, as Stentor (fig. 538, 21). 
‘orticella, according to several recent observers, what has been 
regarded as gemmiparous multiplication—the putting forth of a bud 
Ter raadpleeg ‘tion of a small 
individual in the free-swimming stage with a fully devel fixed 
individual, with whose body its own becomes fused. But it is 
doubtful whether such conjugation has any reference to the encyst- 
ing process. According to Butschli and Engelmann, the conjugati) 
process results in the breaking up of the nucleus and (so called} 
nucleolus of the conjugating individuals ; these individuals separate 
‘in, and after the expulsion of the broken-up nuclear structures 
teristic nucleus and nucleolus are re-formed. The same 
excellent observers adduce strong grounds for distrusting Balbiani’s 


F 


ze 


each consisting the zodspore of of a of 
san eae nnd aed toner i 
wr some eminent observers asserting that the ‘gemmale’ in 
a ssuctorial 
which it imbibes 
Seer Ao) teen ecu 
sclaotloem bodies to H 


of their entire life-history what are to he accounted distinet 
forms. And the differences between them, RerprisS in the 
cir loemotve eninge hn poston of te moth in promot 
other jotive e mout 

of a distinct anal eritisa oad the like, are pest hat trivial 
bch ppbiet pptgalia rial nes nar boing ae at 
and physiology on which we have been dwelling that it does not 
seem desirable to attempt in this to give any detailed account 
of them. ‘The life-history of ciliate Infusoria is a subject 


essrs. Dallinger and Drysdale in the study of the Afc i 

ursuing our researches,’ say these excellent ol ‘we have 
as ‘ically convin of what we have ‘ically assumed 
—the absolute necessity for prolonged and patient observation of 
the same forms. Two observors, i tly of each other, 
examining the cone core if their inquiries hint emer 

rolonged, might, witl ‘utmost tru ness i 
oe rene modes of development. Competent optical means, 
careful interpretation, close observation, and fine are alone capable 
of solving the problem. 


Sxotion I,—Rorirena, on WiHeeL-ANIMALCULES. 


We now come to that higher group of animalcules which, in 
point of complexity of organisation, 18 as far removed from the pre- 
ceding as mosses are from the simplest protophytes, the point 
of real resemblance between the two groups, in fact, the 


1 There oan be no donbt that Stein was wrong in his original doctrine that the 
folly aaveloped' ‘Acineting | are only trandition stages in the development of Vorti- 
are aud other  iliated Tnfusoria, But im re mee 

in favour is later statement, uy bedies figured are 
really infusorian embryow, and not parasitic Acinetw, p 


WHEEL-LIKE ORGANS OF ROTIFERS 713 


as of size which is common to both. A few species of the 
Imalcules are marine, or the inhabitants of brackish pools 
wea-shore ; but the great majority known to us belong to 
ler, and are to be found in ditches, ponds, reservoirs, lakes, 
dy running streams—sometimes attached to the leaves and 
! water-plants, sometimes ing on the Alge, sometimes 

freely through the water. ey are met with also in gut- 
E house-top, in water-butts, on wet moss, grass, and liver- 
the interior of Volvox globator and Vaucheria, in vegetable 
,on the backs of Entomostraca, in the viscera of slugs, earth- 





542.—Rotifer vulgaria,as seen at B, with the wheels drawn in, and 
A with the wheels expanded : b, eye-spots:: c, wheels; <, antenna; 
jaws and teeth; f, alimentary canal ; g, cellular mass inclosing it; 
longitudinal muscles; #, i, tubes of ‘water-vascular system; i, 
ung animal; J, cloacs. 














id Naiades, and in the body-cavities of Synapte—in fact, 
it every place where there are moisture and food. The 
e organs from which the class derives its designation are 
racteristically seen in the common Rotifer (fig. 542), where 
ist of two disc-like lobes or projections of the body whose 
are fringed with long cilia ; and it is the uninterrupted suc- 
E strokes given by these cilia, each row of which nearly re- 
it were) into itself, that gives rise by an optical illusion to 
n of ‘wheels.’ The disposition of the cilia varies much in the 
genera, but it may be said broadly that they are arranged 




















Pra. 648.—Brachic ‘bens: ap, styligerous prominences;: cv, coromal 
wreaths én, acl oat ay eral antatioa} ", @, laberal rr 
orsopl : 5 5 Om, OVNI; 9. KerH 
cia ts ie fk ma pee 
mantax; H a glands? stomach ; 
canals jee, contractile society cl, cloaca; fgfoot gland. [After Ded 


form, similar on the two sides ; but this rarely exhibits any traces of 
segmental division, The body is covered prlecnee apt two 
Wi mat 





layers. The inner of these is a eee to the 
be soft and flexible, or membranous, very Meg pf ae 
stiffness, or even of an inflexible substance capable of ‘the 








the mn of the head, and closed Fi, 544.—Malleate, 
except where a small aper- i, mallet ees belum, 


ra, ramus. 


The anterior dorsal edge bears six fs, inom | Fy, Talerum. 


spi 

a wavy outline. The Acad is shaped like « truncated cone, with the 
end forward, is rounded at each side, and carries on its front 

aun three protuberances («p), covered with stout vibrating hairs 
called styles. All round the rim of the head runs a row of cilia which 
on the ventral surface dips down into either side of a ciliated buccal 
Junnel. At the bottom of the buccal funnel is the mastax (mx), a 
muscular bulb containing the jaws or trophi (ti). These latter are 
hard, glassy bodies euited of two hammer-like pieces called 
mallet (fg. 544) and a third anyil-piece called an meus. Each 
ray (ma) is aye Yeeros Feet man), or handle, 
uneus (ua) ve finger-like processes, which unite to 

form the fried head. The incws (is), or anvil, is formed of two 
pristn-shaped bodies, or rami (rs), ted at their free ends, and 
attached at their broad ends to a thin plate called the fulcrum (fin), 
which, seen ventrally or dorsally, looks like a rod. These various 
Parts are connected by muscular fibres, and so acted on by muscles 
attached to themselves, and to the interior of the mastax, that the 
i rise and fall at the same time that the rami open and shut. 
‘The food is torn by the unci, crushed by the rami, and then passes 
between the latter down a short esophagus (c) into the atomach (#). 
‘This has thick cellular walls, and is lined with cilia, especially at its 
lower third, which is often divided by a constriction from the upper 
part, and is often so different in its shape and contents as to merit 


E 


Cy 





Pio 545. Fw. A ie 
Mo. Bal Lepore Jongi- 


05 penis; 7 fooks fo foot 


On either side of the body is a tortuous tube commencing in & 
plexus in the head and running down to open on the contractile 
vesicle (cv), These tubes bear little tags (vt), each of which Nes rad 
to contain a vibrating cilium. The real structure of these } is 
Enaeetain, and the use of the mole Pec is much ee 

ut the tags are i minut! ciliated funnels, their 
reo a 
of the cavity are jue! » 
tubes, into the peas vesicle, and are by it discharged into the 
cloaca. The sppereis would therefore be mainly an oe 

The ovary is large and its germs are jcuous. a 
oviparous and the huge egg is easily discharged through c 
and cloaca owing to the very fluid condition of its contents. Tt 
retained by a thread till hatched at the bottom of the lorica. There 


i 


a 


E 


1 But see Dr. Hadson's Prosidential Journ. of the i 
woh 1b) ne nr een fr ing i cnt 
may aleo have a respiratory function, and the vibratile tage and. canals 
saouwiagy oon 


ane 
(fig. length Fro. 647, 
is unlike it i ae Tt has « cylindrical 

head, surroundéd by a simple ri 
of cilia, Ts has no loriea ‘nor any alimentary tract of any Kat, 
but it has a nervous system similar to that of the female, a red eye, 
and antenne, i Ocerbdiry aiid sheild rntaaea aie ORE Ee 


female ‘The only other internal organ is a lay sae 
(es) macue Lb its lower extremity in a protrusile, ciliated, hollow 
penis (p), whose outlet holds the position of the anus in the female ; 
that is, on the dorsal surface, at the base of the foot. 


‘The Rotiferahave been divided by Dr. Hudsonand Mr. P. H, Gosse! 
into four orders, according to their sof locomotion. Theseare ; 
1, Ruzora (the . Be when adult. 


a 
z 
Pi 
E 
a 
& 


wreath. 

4, Sctwroropa (the skippers). That swim with their wreath 
and skip with arthropodous limbs. as 

‘The order Khizota contains two families, chiefly differing from 
each other in the position of the mouth, which in the Mosculeriade 

figs. 1 and 2, Plate XV) is central, Yyin in the body's longer axia, 

in the Melicertade: (fig. 3, Plate vy is lateral. Almost all the 
species of both families live in gelatinous tubes secreted by themselves, 
and often fortified in various ways : by débris gathered from the 
water by the action of their ciliary wreaths and showered down at 
random ; by pellets formed in # ciliated cup near the anterior end 
of the body, and deposited in regular order on the gelatinous tube ; 
or by Jarge fecal pellets also regularly deposited. 


4 The Rotifera, or Wheel-animaleules, Longiaus, 1580, 


i 
re 
| i 
He 
il 
i 


z 

E 

F 

A 
TL 
i 

5 

AG 


Lil 
bs 
i 
4 
f 
Me 
i 
f 
i 


a 
| 
Se-8 
lh 
Ma 
i 
i 
i 


Ee 

fie: 
i 
| 
i 


tinous covering which retains the Far 


fg 
i 
F 
1 


ea eee sine l oom Th this order the: not as yet 
Thothint oer lima, is divided int eae and aniline 
wi are not, however, sharp; as in some 
aie cate layaeraes ae este o . ¥ thin and 
flexible. Brachionus fig. 543), has ‘been fully 
described, is a type of the loricata, and C (Be. 6, 
Plate XV) of the iloricata. Most of the species of this order have 


size and shape, but all the Siecle pert 
' ‘ rehire dar I 
riaariberh he pom majority of prvekon et tothe Ploina. 

The fourth order, Sciredcontainsba one Pedationida, 
and has only two genera, Pedalion and Hexarthra, and each of these 


has but one known species. /’edalion (figs. 4, 5, 8, Plate XV) is an 
extraordinary creature. Its internal organs are on erat wll 
plan, but its body bears no fewer than six hollow limbs, ending in 
plumes like those of the Arthropoda, and worked by pairs of opposing 
muscles which traverse their entire length. These limbs are ar- 
rat round the body, some on the dorsal, some on the ventral 
and all running parallel to the body's longer axis. In 
Hexarthva, on the contrary, all the limbs are on the ventral surface, 
and are arranged radiatingly. ‘There is no foot in either Rotiferun ; 
but in Pedation there are two ciliated club-like processes at the 
terior extremity, rising above the dorsal surface and 
4 similar viscous fluid to that secreted in the toes of other 
207; 


Rotifera, 
} Seo Davis in Monthly Micros. Jorern, vol. ix, 1 Stack, at p. 241 of 
same volume ; and She rept 7 diceusaion on the vata at tbe eal 


pical Society, Jowrn, of Hoyal Microw. Soc, 1887, p, 179, . 


PLATE XY 





West Newman chromo 


yypical Kouters 





BIBLIOGRAPHY OF ROTIFERS 719 


ge creature was discovered by Dr. C. T. Hudson ina pond 
im_ 1871; Hexarthra was discovered by Dr. Schmards 
a ditch near the Nile in 1853; their arthropodous limbs 
. strong resemblance to 4 ‘Nauplius larva, and make it 
‘tthe Rotifera will have to be placed between the VERMES 
oPpopa. 


wing treatises and memoirs) in addition to those already referred to) 
Te information in regard to the life-history of animalcules and their 
as Ehrenberg, Dic Infusionsthicrchem’ Berlin, 1888; Dujardin, 








relle des Zoophytes infusoires, Paris, 1841; Pri story of 
2 ek 1861 (a com repertory of information) ; 
‘anternus i iprig: Erste Abtheilung, 1859; Zweite 
‘Dritte Abtheilung, Hiltte I. 1878. Saville Kent's Manual al of the 
and pred Bicechits Protozoa (1880-1) in the new edition of 
treichs. ‘Or Rhizopods and Infusoria see Cl 
an, Etudes sur los Infusoives ot les Bhi , Geneve, 1868-61; 
old. und Kolliker's Zeitschrift, 1851-4 1857; Tieberktthn, in 


fg, 1856, and Ann. oe Hist’ and sor. yo, xvii 856; 
schichte der Inf i, and Professor Biitechi 





on Lacinularia sociali 

1858, 1; Cohn an Bisbold und Rother Zettacheyh 
856, 1858; Dr. Moxon, Trans. Linn. Soc. 1864; Karl Eckstein, Stebold 
8 Zeitschrij rat Potifera, in the Sth edition ofthe Ency- 
tannica ; Mélicertes,’ viv. ool. expér. wér. 
31; end SF eo eiache iano 1. "The Bokifora, or Whee. 
1869. Mr. Slack’s Marvels of Pond 

fendon Sil), contaian many intorenting observations om the habit of 

fers. 






































FORAMINIFERA 720 


s, or many-chambered (Plates XVI and XVII), often so 
resembling those of Vautilus, Spirula, and other cephalopod 
that it is not surprising that the older naturalists, to whom 
of these animals was entirely unknown, ranked them 
class. But independently of the entire difference in the 
of the animal bodies by which the two kinds of shells are 
is a most important distinction between them in regard 
relation of the animal to the shell. For whilst in the 
shells of the Vautilus and other cephalopods the animal 
individual tenanting only the last formed’ chamber, and 
itself from each chamber in succession, as it adds to this 
larger one, the animal of a nautiloid foraminifer has a 
body, consisting of a number (sometimes very large) of 
, each repeating the rest, which continues to increase by 
or budding from the last formed segment. And thus snake 
bers, however numerous they may be, is not only formed, 
to be occupied by its own segment, which is connected 
segments of earlier and later formation by a continuous 
(or creeping stem), that passes through apertures in the 
itions dividing the chambers. From what we know of 
fluid condition of the sarcode-body in the reticularian type, 
be little doubt that there isan incessant circulatory change 
substance of each segment ; so that the material taken 
by the segments nearest the surface or margin is speedily 
sh the entire mass. The relation between these * poly- 
? forms, therefore, and the monothalamous or single- 
of which we have already had an example in Gromia, 
‘which others will be presently described, is simply that, 
any buds produced by the latter detach themselves to form 
individuals, those put forth by the former remain in con- 
with the parent stock and with each other, so as to form a 
ite’ animal and a ‘polythalamous’ shell. 
ling to the plan on which the gemmation takes place will 
configuration of the shelly structure produced by the seg- 
body. Thus, if the bad. should. be put forth from the 
of a Layenu (Plate XVII, fig. 12) in the direction of the 
its body, and a second shell should be formed around this 
continuity with the first ; and this process should he succes- 
repeated, a straight rod-like shell would be produced, whose 
chambers communicate with each other by the openings that 
ly constituted their mouths, the mouth of the last-formed 
ber being the only aperture through which the protoplasmic 
, thus composed of a number of segments connected by a 
or ‘stolon’ of the same material, could now project itself 
w in its food. The successive segments may be all of the 
size, or nearly so, in which case the entire rod will approach 
ieylindrical form, or will resemble a line of heads ; but it often 


mepried on differentiating Ut type from the Forausinitera proper. Dut the 
sof Hertwig and Lesser, F. E, Schulze, Biitschli, and others, having estas 
ted its prrenence in severnl trae Foraminifera, and the Author's own observations 
lag confirmed these, its general prevence may be fairly ussumed. F 

‘ Ba 








722 MICROSCOPIC FORMS OF ANIMAL LIFE 


happens that each mere Ts iss SAIN larger than the 

(fig. 18), me het the Gree a conical form, the apex: 

the cone meen its hase the one last formed, 

Thormetiod ol grows now eRe seth ao 

of Foraminifera, chiefly belonging to the sub-family Ve y 

but even in that group we have Rog A tomeeray ih vi lpron a 

Jineal (fig. 10) and the spiral mode of growth (| (Bette 

the genus Peneroplis it is not at all uncommon for 

menece in a spiral to exch: this in a more erate 

rectilineal habit. When ey iver ive ponies mk 

spiral direction, the character spire great ese 
the enlargement or non- ule the successively formed 

antees for sometimes it opens out very rapidly, every whorl: 

being considerably broader than. that rhc it it surroands, in con- 

sequence i the preahecsoets of ieee tee eee 

predecessor, as in Peneroplis, fig. 548 ; but more commonly there 

ao little difference between the successive segments, after the ee 

has wade two or three turns, that the breadth of each whorl scarcel; 

exceeds that of its predecessor, as is well seen in the section of rd 





Fro. 648.—Foraminiters;—Peneroplis and Orblentinnt. 


Rotalia vepresented in fig, 566, An intermediate condition is pre- 
sented by /ofalia, which may be taken as « characteristic type of 
a very large and important group of Foraminifera, whose general 
features will be presently described. Again, a spiral be 
either ‘nautiloid’ or ‘turbinoid,’ the former designation 
applied to that form in which the successive convolutions all 
lie in one plane (as they do in the Nautilus), so that the shell 
is ‘equilateral’ or similar on its two sides; whilst the latter is 
used to mark that form in which the spire passes round 
an axis, so that the shell becomes ‘inequilateral,’ having a more 
or less conical form, like that of a snail or a periwinklo, the first- 
formed chamber being at the apex. Of the paises we have charae- 
toristic examples in Polystonella (Plate X VIL, fig. 2) and Vontontsa ; 
whilst of the latter we find a typical representation in Aofalia 
Beecarii ( 2). Further, we find among the shells whose ihereas 
takes place upon the spind plan a very marked difference as to the 
degree in which the earlier convolutions are invested and concealed 
by the latter. In the great rofeline group, whose chapweteristic 
form is a turbinoid spiral, all the convolutions are usually visible, 
at least on one side (fig, 17); but among the nantiloid tribes it more 















Plate Xi] 





FORAMINIFERA 723. 


frequently happens that the last-formed whorl encloses the preced- 
ing to such an extent that they are scarcely, or not at all, visible 
externally, as is the case in Cristallaria (tig. 17), Polystomella (lig. 23), 
and Vontoning. The turbinoid spire may coil so rapidly round an 
elongated axis that the number of chambers in each turn is very 
small ; thus in @obigerina ( 2, 21, Plate XVII) there are 
usually only four; and in Valewlina the regular number is only 
three, Thus weare led to the diserial arrangement of the chambers, 
which is characteristic of the tertularian group (fig. 8, @, 6, and 9, 
Plate XVI), in which we find the chambers arranged in two rows, 
each chamber communicating with that above and that below it 
on the opposite side, without any direct communication with the 





Fra, 649, —Discorbina globularis (Hosalina varias, Schultze), 
with its pseadopodia extended. 


chamber of its own side, as will be understood by reference to fig. 
564, A, which shows a ‘cast’ of thesarcode-body of the animal. On 
the other hand, we find in the nautiloid spire a tendency to pass 
(by « curious transitional form to be presently deseribed) into the 
cyclical mode of growth ; in which the original segment, instead of 
budding forth on one side only, develops géwnve all round, so that 
a ring of stall chambers (or chamberlets) is formed around the 
primordial chatnber, and this in its turn surrounds itself after the 
Tike fashion with another ring ; and by successive repetitions of the 
same process the sliell comes to have the form of a disc made up of 
a great number of concentric rings, a5 we see in Ortitofites (fig. 551) 
and in Cyeloelypeus (fig. 569). 








8.2 


Plate XVII 


AT Matied dh 
A TYPICAL GROUP 





IF TORAMIMIFERA i 





FORAMINIFERA 725, 




















seen by transmitted light under a higher magnifying 
as is shown in i. 574, 575. When they are very numerous 
set, the shell derives from their presence that kind of 
ich is characteristic of all minutely tubular textures, 
are occupied either by air or by any substance having 
wer different from that of the intertubular substance, 
mnay be the transparence of the latter. The straight- 
ism, and isolation oF these tubuli are well seen in verti- 
8 of the thick shells of the largest examples of the group, 
Nummiuilites (fig. 573). It often happens, however, that 
parts of the shell are left unchannelled by these tubuli ; and 
readily distinguished, even under a low magnifying power, 
readiness with which they allow transmitted light to pass 
gh them, and by the peculiar vitreous lustre they exhibit when 
thrown obliquely on their surface. In shells formed upon 
we frequently find that the surface presents either bands 
which are so distinguished, the non-tubular bands usually 
the position of the septa, and being sometimes raised into 
though in other instances they are either Jevel or somewhat 
3 whilst the non-tubuler spots may occur on any part of 
, and are most commonly raised into tubercles, which 
attain a size and number that give a very distinctive 
to the shells that bear them. 
the comparatively coarse perforations which are common 
rotaline type, and the minute tubuli which are characteristic 
nummuline, there is such a continuous gradation as indicates 
their mode of formation, and probably their uses, are essen- 
the same. In the former, it has been demonstrated by actual 
ion that they allow the passage of pseudopodial extensions 
sarcode-body through every part of the external wall of the 
occupied by it (fig. 549) ; and there is nothing to oppose 
idea that they answer the same purpose in the latter, since, 
as they are, their diameter is not too small to enable them 
traversed by the finest of the threads into which the branching 
ia of Foraminifera are known to subdivide themselves. 
the close approximation of the tubuli in the most finely 
ted numimulines makes their collective area fully equal to 
pot the larger but more scattered pores of the most coarsely per- 
rotalines. Hence it is obvious that the tabulation or non- 
ion of foraminiferal shells is the key to » very important 
iological difference between the animal inhabitants of the two 
respectively ; for whilst every segment of the sarcode-body in 
former case gives off pseudopodia, which pass at once into the 
ing medium, and contribute by their action to the nutrition 
segment from which they proceed, these pseudopodia are 
Mited in the latter case to the final segment, issuing forth only 
Whrogh the aperture of the last chamber, so that all the nutrient 
terial which they draw in must be first received into the lust seg- 
Smet, and be transmitted thence from one segment to another until 
aches the earliest. With this difference in the physiological con- 
ion of the animal of these two types is usually associated a further 









PORCELLANOUS FORAMINIFERA 727 




























terised will be best understood by examining, in the first 
fi the form which has been designated as Spiroloeulina. This 
spiral, elongated in the direction of one of its diameters, 
, at each turn a contraction at either end of that diameter 
ly divides each convolution into two chambers ; the 
mp between the consecutive chambers is often made more 
‘by @ peculiar projection from the inner side of the cavity, 
the ‘tongue’ or ‘valve,’ which may be considered as an 
septum. Now it is a very common habit in the milioline 
the chambers of the later convolutions to extend themselves 
of the earlier, 0 as to conceal them more or less com- 
nd this they very commonly do somewhat unequally, so that 
} the earlier chambers are visible on one side than on the 
iolee thus modified (tig. 1, Pl. XVI) have received the names 
oculina and Triloculina according to the number of 
visible externally ; but the extreme inconstancy which is 
mark such distinctions, when the comparison of specimens 
sufficiently extended, entirely destroys their value as differ- 
rs, and the term Jiliolina is now more frequently 
to them collectively. Sometimes, on the other hand, the 
pnvolutions are so completely concealed by the later that only 
chambers of the last turn are visible externally ; and in this 
ich has been designated Ailoculina, there is often such an 
in the breadth of the chambers as altogether changes the 
oportions of the shell, which has almost the shape of an egg 
o placed that either the last or the penultimate chamber faces 
erver. It is very common in milioline shells for the external 
to present a ‘pitting,’ more or less deep, a ridge-and-fw 
Sgement (fig. 3), or » honeycomb division ; and these di 
een used for the characterisation of species, Not only, how- 
may every intermediate gradation he met with between the 
strongly marked forms, but it is not at all uncommon to find 
: ‘smooth on some parts, whilst other parts of the surface 
same shell are deeply pitted or strongly ribbed or honey- 
d; so that here, again, the inconstancy of these differences 
es them of much of their value as distinctive characters. 
‘An interesting illustration of the tendency to dimorphism 
gat the Foraminifera has-been observed by MM. Munier 
and Schlumberger! in the structure of the shells of this 
p. They find that while two forms, which they distinguish as 
A and form B, are similar externally they differ in internal 
tare, form B having its initia] chamber much smaller than 
of form A, and this ‘microsphere’ is followed by a larger 
er of chambers than is the ‘megasphere’ ot form A. What 
difference signifies it is at present impossible to say, but it has 
suggested that it may be one of sexual character. The ob- 
tions of the French naturalists referred to open out a new field 
iaquiry, and one which is enjoying the attention of several works 
department of research. 
ing again to the primitive type 
1 Bulletin Soc. Geol, se 











sented in the simple 
73. 






vol. 








PORCELLANOUS FORAMINIFERA 729 


adjacent rows, The later turns of the spire very commonly grow com- 
pletely over the earlier, and thus the central | or umbilicus” 
comes to be protuberant, whilst the growingedge is thin. The 
also opens out at its i which tends to encircle the 
formed portion, and thus rise to the peculiar shape sented 


esa and with i the 
bl jumns, with a ter con i 
ee 
a ie mn) are 
Be nn ty hone ih ako ups cnn a of 
jiary jimestone on the Malabar coast of India, whose diameter 
reaches seven or eight lines, 
A very curious modification of the same general plan is shown in 
Aleeoline, a genus of which the largest existing forms (fig. 550) are 


commonly about one-third of an inch long, while far specie, 


mens are found in the Tertiary limestones of Scinde. Here the 
ire turns round a very elongate axis, so that the shell has almost. 
form of a cylinder drawn to a Rol at each extremity. Its 
surface shows a series of longitudinal lines which mark the principal 
versely ae ey caaea the ravines ok tha cautcead cote 
ines wl subdivision o! ineipal cham! 
into ‘chamberlets.’ The chamberlets of each row ad connected with 
other, as in the type, by a continuous gallery ; and 
{hee nal those re the aS a Cet multiple 
pores incipal septa, such as constitute the external orifices of 
the eae toraced series, seen on its septal plane at a, a. 

The highest development of that cyclical pee of growth which 
we have seen to be sometimes taken on by Orbiculina is found in 
Orbitolites ; 0 type which, known asa very abundant fossil in 
the earlier Tertiaries cf the Paris basin, has lately proved to be 
searcely less abundant in certain parts of the existing ocean, The 

recent specimens of it, sometimes attaining the size of a 

have hitherto been obtained only from the coast of New 
Holland, the Fijian reefs, and various other parts of the Polynesian 
Archipelago ; but discs of comparatively minute size and simpler 
ion are to be found in almost all foraminiferal sands and 

ings from eee ae a rns ean et the globe, being 

jally abundant in those of some of the Philippine Islands, of the 


ui 


3 
E 


cy 


at 


a 


730 MICROSCOPIC FORMS’ OF ANIMAL LIFE 


Red Sea, of the Mediterranean, and especially of the Agean. When 
such dises are subjected to microscopic examination, they are found 
(if uninjured by abrasion) to present the structure represented in 
5 551, where we see on the surface (by incident light) a number 

rounded elevations, arranged in concentric zones around a sort of 


Fro. 65.—Aleeotina Boseii : a, lateral aspoct; b, lermital aypect 6, transverse section of shell, 





nucleus (which has been laid open in the figure to show its internal 
structure) ; whilst at the margin we observe a row of 

Jjections, with a single aperture or pore in each of the intervenin, 
depressions, In very thin discs the structure may often be brought 
into. view by mounting them in Canada balsam and transmitting 


li ‘ 


7 “) ORBITOLITES 731 


light wae them; but in thése which are too opaque to be thus 
seen through, it is suficient to rub down one of the surfaces upon a 
stone, and then to mount the spectre in balsam. Each of the 
superficial elevations will then be found to be the roof or cover of an 
ovate cavity or ‘chamberlet,’ which communicates by means of a 
lateral passage with the chamberlet on either side of it in the same 
ring ; so that each circular zone of chamberlets might be described 
asa continuous annular passage dilated into cavities at intervals. 
On the other hand, each zone communicates with the zones that are 
internal and external to it by means of passages in a radiating 
direction ; these passages run, however, not from the chamberlets of 
the inner zone to those of the outer, but from the connecting pass- 

of the former to the chamberlets of the latter ; so that the 
chamnterida of each zone alternate in position with those of the zones 


ws es week re ry Sad 





Fre, 551.—Orbitolites, Ideal representation of « disc of complex type, 


internal and external to it. The radial passages from the outermost 
annulus make their way at once to the margin, where they termi- 
nate, forming the ‘ pores’ which (as already mentioned) are to be seen 
on its exterior. The central nucleus, when rendered sutticiently 
transparent by the means just adverted to, is found to consist of a 
‘primordial chamber’ (a), usually somewhat pear-shaped, that com- 
tmunientes by « narrow passage with a much larger ‘ circumambient 
} ehamber’ (6), which nearly surrounds it, and which sends off a vari- 
able number of radiating passages towards the chamberlets of the first 
zone, which forms a complete ring round the circumambient chamber," 


# Although the abore may be considerd the typical form of the Orbitolite, Shed 
ine very proportion of specimens, the first few zones are not complete cirdes, 
the early growth having taken place from one aide only; ani there is « very beaatifal 
variety in which this one-sidednews of increase imparts a distinctly spiral character 
to the early growth, which soon, however, gives place tothe eyclion!, In the Orbito- 
Tites italien (6g. 863), brought up trom dopthn of 1500 fathouse ut more, the “nucleus 











732 MICROSCOPIC FORMS OF ANIMAL LIFE 


‘The idea of the nature of the! occupant of these cavities 
which might be suggested by the 
ment, is fully borne out by the | of the examination of 
the sarcode-body, which be obtained by the maceration in 
dilute acid (so a8 to remove investment) of specimens of 
Orbitolites that have been gathered | and in 


substance. 
have budded off its ‘ cirew ient' segment, 6, by a narrow foot- 

and this ci bient. after almost- 
stalk or stolon circumam!| See passing ay 
swell into new sub- 


entirely round the primordial, has 





Fro. 652.—Composite animal of sito] of Orbite- 
lites ries noire eee ee sarod 5 


b, ient segment, giving off pedancles, tn «jy 
which originate the conceatre zonbe of Fabsaagmenta tH@ example before us) 


connected by aunular bands. ue number of fons 
tremely small. Ench zone is seen to consist of an assemblage of 


ovate sub-segments, whase hat (which could not be shown in the 
figure) corresponds with the thickness of the dise; these sub-seg- 
ments, which are all exactly similar and equal to one another, are 
connected by annular stolons ; and each zone is connected with that 
on its exterior by radial extensions of those stolons passing off be- 
tween the sub-seginents. 

The radial seine a the outermost zone Rot forth - 
pseudopodia from the marginal pores, i 
peers materials in the manner Posten rae the whole 
of the soft body, which has no communication whatever with 
ia formed by three or four turns of a spiral cot ® 

by spiral closely teed asta whe 


with an interruption at every half-tarn, as in gtowth 
wards becoming purely concentric, 


ORBITOLITES 733 


the exterior, save through these marginal pores, being nourished 
by the transmission of the products of digestion from zone to zone 
through similar bands of protoplasmic substance. In all cases in 
which the growth of the dise takes place with normal regularity it 
is probable that a complete circular zone is added at once. Thus 
we find this simple type of organisation giving origin to fabrics of 
hy no means microscopic dimensions, in which, however, there is no 
<ther differentiation of parts than that concerned in the formation 
of the shell, every segment and every stolon (with the exception of 
the two forming the ‘nucleus’ ) being, so far as can be ascertained, 
& precise repetition of every other, and the segments of the nucleus 
differing from the rest in nothing else than their form. ‘The equality 
of the endowments of the segments is shown by the fact—of which 
accident has repeatedly furnished proof—that a small portion of a 
dise, entirely separated from the remainder, will not only continue 





Fie. 558,—Dise of Orbitolites italice, Costa, sp. (O. tenuissima, Carp), 
formed round fraginent of proviows dine. 





93), the want 
t consequence, 
outer zones, 

of this type is its 


to live, but will so increase as to form a new disc (fig. 
of the ‘nucleus’ not appearing to be of the slight 
from the time that active life is established in the 

One of the most curious features in the histo 
capacity for developing itself into a form which, whilst funda- 
mentally the same as that previously deseribed, is very much more 
complex. In all the larger specimens of Orbitolites we observe that 
the marginal pores, instead of constituting but a single row, form 
many rows one above another ; and, besides this, the chamberlets 
of the two surfaces, instead of being rounded or ovate in form, are 
usually oblong and straight-sided, their long diameters lying in a 
rudial direction, like those of the cyclical type of Orbiculina. When 
a vertical section is made through such a disc, it is found that these 
oblong chambers constitute two superficial layers, between whieh 























ee, dd, ing do hy ade, sonata Beese pact an annulus, but 
nm its and communicating 


zone, 
of the intermediate layer ; for these columns (¢ ¢ ¢ «) 
terminate above and below in the annular stolons, sometimes passin, 
directly from one to the other, but sometimes going out of their 
direct course to coalesce with 





pseudopodia. 
—Portion of animal of complex Now this plan of growth is 
of  Orbitolifer complanata: so different from that previously 
an’, bd’, the upper and lower ringkot described that there would ut 
two’ concentric zoues; cc, the upper 
layer of superficial «ub. ‘and first seem ample ground for 
sid, the lower layer, connected with the separating the suple and the 
anular bands of both zones; ¢¢ and las tepenma di cacy 
od, vertical sub-ingmonte of the two  SOMPle® EYPOs 
Sone But the test furnished by the 
- A examination of a are nuember 
9 passed 
of specimens, which ought never to be by when it can ly 
be appealed to, furnishes these very singular results : Ist, ineynd 
two ss must be considered as specifically identical ; since there ix 
not only a gradational passage from one to the other, bat they ary 
often combined in the same individual, the tener and first-formed 
portion of a large dise frequently presenting the simple type, whilst 
the outer and later-formed part has developed itself upon eapeDlaet 
2nd, that although the last-mentioned circumstance would 
suggest that the change from the one plan to another may be simply 
a feature of advancing age, yet this cannot be the case = since, 
although the complex sometimes evolves itself even from the 
first (the ‘nucleus,’ though resembling that of the simple form, 5 






= 


ARENACEOUS FORAMINIFERA 735 
‘out two or more tiers of radiating threads), more frequently the 
oe Ad al hahe eles Septal drapes pain : 


in the course of a few zones into the complex, No 


and ent veplaced by a sandy envelope, which is distinguished as 

me arenaceous particles eine held eaalee ealy by a 
cement exuded by the animal. It is not a little curious that the 
dierent pes Teh the teeclanee ad belies’ 
i it among the § the ‘ vitreous” 
series ; whilst they luate into one another in such a manner 


i 


j 
& 
; 
s 
i 
a 
i 
3 
B. 
s 
e 


iii teres 
have brought up few forms of either ‘porcellanous’ or ‘vitreous? 
Foraminifera that were not previously known, they have added 
greatly to our knowledge of the ‘arenaceous’ types, the number and 
variety of which far exceed all previous conception, These have 
been untically described by Mr. H. B, Brady, F.R.S.* whose 

es have led him to believe that the long-established division 
of the Foraminifera into the arenaccous and calcareous groups does 


Wits Pola oneeney oie peal ot rita seo the sty '* scone 

Uy inte of . Chal Mr, H. B. Brady in his* Challenger” 
Report Up. Wi) doccrines a romarkable allied type from the Southern Ovesu— 
Keramesphoero Morrayi—in which tho text is spherical, and the ebambers are 


a ae isa the Foraminifers dredged by H.31.5. Challe 
Sc report 02 tere LSS, Challenger 
{0884), iby 116 plates. ‘} 





SACCAMMINA AND PILULINA 737 


the first of which, Astrorhizida, includes with the preceding 
r of coarse sandy forms, usually of considerable size, an 
y monothalamous, though sometimes imperfectly chambered 
Actions atintervals. Some of the more interesting examples 
emily will now be noticed, beginning with the Saccammina 
hick i is a remarkably regular type, composed of coarse sand- 
amily cemented er in a globular form, so as to constitute 
arty smooth on the outer, though rough on the inner surface, 
neck surrounding a circular mouth (fig. 555, a, b, 
8 type, which occurs in extraordinary abundance in certain 
8 (as the entrance of the Christiania fjord, and still further 





[ee Arenscoons Foraminiters a, Saccammtina epherion  b the eame 

Bat epen of the test, enlarged to show its component sand- 

ord, Pilutina 4 “segey -ysii; ¢, portion of the test enlarged, showing 
arrangement of the sponge-spicules. 





on the shores of Franz Josef Land), is of peculiar interest 
the fact that a closely allied species (Saccammina Carteri) is, 
t. H. B. Brady has shown, one of the chief constituents of 
in beds of the cower Carboniferous limestone of the north of 
ad and elsewhere. In striking contrast to the preceding is 
er single-chambered type, distinguished by the whiteness of 
xt,’ to which the Author has given the name of /ilulina, from 
wemblance to a homeopathic ‘globule’ (fig. 555, «, +). The 
of this is a very regular sphere ; and its orifice, instead of 
cireular and surrounded by a neck, is a slit or re with 
ly raised lips, and having a Somewhat S-shaped curvature. It 
the structure of its ‘test,’ however, that it is especially dis- 
shed ; for this is composed of the finest ends of sponge-spicules, 
egalarly ‘laid’ so as to form a kind of felt, through the sub- 
of which very fine sand-grains are dispersed. This ‘ fale: is 
B 





738 MICROSCOPIC FORMS OF ANIMAL, LIFE 


somewhat flexible, and its components do sot seém to be united 
any kind of cement, as it is not affected by bei ed areeey 
nitric acid ; its tenacity, therefore, seems ¢ 

wonderful manner in which the separate p 

Tt is not a little curious that these two forms should present them- 
selves in the same dredging, and that there should be no 
difference in the character of thei 








Fie, 656.—A) Foraminifera: and bower of. 
ssivagradany gloviperanureiss'@ Bir tae Olaly eae a asene 
elongata; ¢, terminal Pexion, and f, middle portion of the same, enlanged ; 

immnina apt 


 Thural 


ilata ; d, portion of its inner surface, enlarged. 


they come up with ‘Globigerina mud,’ in which fy soared 
abound, whilst sand-grains are searce, they are entirely 
made up of the former, which are ‘Inid’ in a sort of lattice-work, 
the interspaces of which are filled up by fine sand-grains ; but when 
they are brought up from a bottom on which sand predominates, 
the larger part of the ‘test’ is made up of sand-grains and minute 
Foraminifera, with here and there a 5] joule (fig. 556, d, /). 
Tn each case, however, seston * exten) feeling che} some- 
times forms a sort of proboscis, e, nearly 

in length) are entirely made up of spongerhadlon Hil side by side 
with extraordinary regularity. The genus Riabdammina (Sars) 
resembles Saccammina in the structure of its ‘test,’ which is com- 
posed of sand-grains very firmly cemented together ; but the grains 


sf 
i 


ae 
E 


3 
Et 
x 
z 


Lituolida.—The of this family, which is named after it, is 
a lange, sandy, many-chambered fossil form occurring in the chalk, 


blance in shape to a crosier, A great variety of recent forms, mostly 
obtained by dee} dredging, are now included in it, as hearing 
a more or lose resem! to it and to each other in their 
chambered structure, and in the arrangement of the sand-grains of 
which their testa are formed. These grains are, for the most part, 
finer than those of which the tests of the fing family are con- 
structed, and are set (so to speak) more artistically, and a con- 
siderable quantity of a cement exuded by the animal is employed 
them. This da often mixed up with sandy particles of 
to form a sort of ‘plaster’ with which the exterior 

t is smoothed off, 30 a4 to present quite a polished surface, 
‘kable that the cement contains a considerable quantity 
of iron, which imparts a ferruginous hue to the ‘tests’ in 
it is largely employed, The forms of the Litwoline ‘ tests” 
simulate in a very curious way those of the simpler types of 
vitreous series. Thus, the long spirally coiled undivided sandy 
of Ammodisous is the ico of Spirillina. In the genus 
minum (tig. 556,,b,and Plate XV, fig. #) we have singular 

of the Globigerine, Rotaline, and Nonionine types ; and in 


4 See Saville Kent in Ann. of Nat, Hist. sor. v. vol. il, 1878; Professor 


Tan. 
fe Quart. Journ: Micros, Sei. vol. six, 1870, p.470;, and Profewor Mabiay” 
won Mawrifina, 1289. ne 
2 


" 


the 
it is 


nen 





i 


740 MICROSCOPIC FORMS OF ANIMAL LIFE 

Thurammina papi 5 not less remarkable imitation of 

se Ostalicg Ty lactis sptccely meee oot the 

Cae ae Tal very cuibrar ar aea as tele gees 
a 

iseaier te to"pcénen  aikuioaltqatate RO} benenial ptt 


AP pee heli SY protuberances, in 
of which there is a rounded oritice. aie 


: 

& 

! 
Q % 

HY 
Haid 


z 
: 
z 
3 
i 
c 
é 
Be 


‘tests being sometimes constructed with the egal characteristic 
of the shelts of the true Nodoseria, Plate XVIT, 16, whilst ia other 





Frio, 557,—Arenaceous Foraminfera; , 4, exterior and sectional views of 
Rheophax subulosa: ¢, Rhablammina im; 4h, Crose-soction of ot 
of ite armas; «, Rhecphax scorpiurus; f, Hormosina Carpenteri- 


cases the chambers are less regularly disposed 557, f), ha 
rather the character of bead-like tnlidgensmats a patie LEA Brett 
les being 


walls show a less exact selection of spon; 

worked in with the sand-grains, so as to them 4 hirsute 

A greater rudeness of structure shows i in the Nodosarine 

of the genus Rheophax, in which not only are the sand. of the 

‘test very coarse, but small Foraminifera are often worked ap with 

them (fig, ce). A straight, many-chambered form of the same 

genus (fig. 557, «, 8) is remarkable for the peculiar finish of the neck 

of each segment ; for whilst the test generally is composed of sand- 

grains, as loosely aggregated as those of which the test of 4. 

is made up, the grains that form the neck are firmly united by 

ruginous cement, forming a very smooth wall to the tubular orifice, 
‘The highest development of the ‘ arenaceous’ type at the present 

time is found in the forms that imitate the very regular nautiloid 








i 


CYCLAMMINA 74l 


woth of the ‘porcellanous’ and the ‘vitreous’ series ; and the 
ble of these is the Cyclammina cancellata (fig. 558), 

‘been brought up in considerable abundance from depths 
downwards to 1900 fathoms, the largest examples being 
in 700 fathoms. The test (fig. 558, a) is composed of 
sand-grains firmly cemented together and smoothed over 
with ‘plaster,’ in which large glistening sand-grains are 
set at regular intervals, as if for ornament. On laying 
spire it is found to be very regularly divided into chambers 
zs formed of cemented sand-grains (5), a communication 
wm these chambers being left by a fissure at the inner margin 
i spire, as in Operculina (fig. 570). One of the most curious 
mm the structure of this type is the extension of the cavity 
fh chamber into passages excavated in its thick external wall 











Fro. 658.—Cyclammina cancellata, showing at a, its external aspect; 
8, its internal structure ; c, a portion of its outer wall in section, more 
highly magnified, showing the sand-gruins of which it is built up and 

passages excavated in its substance. 


h passage being surrounded by a very regular arrangement of 
ignins, as shown at c. It not unfrequently happens that the 
wlayer of the test is worn away, and the ends of the passages 
ushow themselves as pores upon its surface ; this appearance, 
‘ever, is abnormal, the passages simply running from the chamber- 
ity into the thickness of its wall, and having (so long as this is 
thasy no external opening. This ‘labyrinthic’ structure is of 
$ interest, from its relation not only to the similar structure 
we large fossil examples of the same type, but also to that which 
wsented in other gigantic fossil arenaceous forms to he presently 


sh some of the nautiloid Lituol are among the largest 
xisting Foraminifera, having a diameter of 0°3 inch, they are 
» dwarfs in comparison with two gigantic fossil forms, whose 





742 MICROSCOPIC FORMS OF ANIMAL LIFE 


igs hve worked ver the rend of Conger 
who have worked over the Greensand of 

tee Ne AE si sr ey wh hr 

t unfrequently, varying in size from a 

oer Se cere 


them as mineral concretions, others were led =i png 
WR opesanes having bone fotacaaly ih oe ti 

A en havi 

the original hile hog pweirnne Sevraettyp eth d rahol rei 





Fin. 559.—General view of the internal structure of Parkeria: In the hori 
fcc Aste th hora! svt ef ne epee 
tio o tern a 
fencture; B, the Sypearance peel a cimilar fructuro passing throwgh 
the radiating processes; C, the result of » Cayo peotion passing 
iReccels the ncanatieles echomnanan a lamnella; he appenrasce pew. 


vented by the external eurface of lamella. separated 
Ffuctave hich han passed taaseeh Use fala protests Me Tbe 
section takes tn a redial direction, bo aa 46 Grden lips maid 

intervening spaces; ¢},c°, o ct, successive chambers 


filtration, it was aubmitted by Professor Morris to the Author, who 

‘was at once led by his examination of it to ise it as a member 

of the arenaceous group of Foraminifera, to which he gave the de- 

signation Parkeria, in compliment to his valued friend and 

Mr. W. K. Parker. A section of the sphere taken through its 

centre (fig. 559) presents an aspect very much resern that of an 

Orbitolite, a series of chamberlets being Repeat 

round a ‘nucleus’; and as the same pppeasaice Slee 

ever be the direction of the section, it es apparent that er 

Seo thuir ‘Description of Parkeria and ‘in Transac. 
1869, p 721. Though it apy pce tem lon ihe ban of 

to remain, it must be noted thi moat 

- inion that Parkeria ix 


of the Stromatoporoide—ais 
fownil Hf memoir by Professor Alleyne Nicholson, published 
Elie by the Priwontageaphioal Society). " 


a 


Hi 









‘inifig, 559, cl, o%,:c3, ¢% sometimes 
forming « spiral, and in one in- 


Orbitolite extends itself round the primordial chamber ; and radial 
prolongations given off from this in every direction form the first 
investing sphere, round which the entire series of concentric 
spheres are successively formed. Of the sand of which this remark- 
cable fabric is constructed about 60 per cent, consists of phosphate of 
Time, and nearly the whole remainder of carbonate of lime. Another 
large fossil arenaceous type, constructed upon the same general plan, 
but growing spirally round an elongated axis, after the manner of 
Alveotina (fi BO), and attaining a length of three inches, has been 
described by Mr. H. B. (loc, cit.) under the name ia, after 
its discoverer, the Iate Mr. W. K. Loftus, who brought it from the 
‘Turko-Persian frontier, where specimens were found in considerable 
numbers imbedded in ‘a blue marly limestone,’ probably of early 

Thae is nothing, it seems to the Author, more wonderful in 
Nature than the building up of these elaborate and symmetrical 
structures by mere ‘jelly-speck ’ presenting no trace whatever of 
that definite ‘organisation which we are accustomed to regard as 
necessary to the manifestations of conscious life. Suppose a human 
‘mason to be put down by the side of a pile of stones of various shapes 
and sizes, and to be told to build a dome of these, smooth on both 
‘surfaces, without using more than the least possible quantity of » 
vot estes but costly cement in holding the stones together. 
Tf! eda this well, he would receive credit for great in- 
telligence and skill. ‘Yet this is exactly what these little ‘ jelly-specks” 





=i 





GLOBIGERINIDA 748. 


of which many are to be met with on our own shores, but which are 
more abundant on those of the Mediterranean and especially of the: 


another Polymorphina, 
the shell to be made up of lageniform chambers arranged ina double 
series, alternating with each other on the two or more sides of a 
rectilinear axis; here, again, the forms of the individual chambers, 
and the mode in which are set one uy another, vary in such 
& manner as to give rise to very marked differences in the 
cont ‘tion of the shell, which are indicated by the name it bears. 
bigerinida.—Roturning once again to the simple ‘ monothala- 
mous” anarge we have in Sr baling—* minute spherical pall that 
itself in greater or abundance in deep-sea dredgin, 
Seratatnce gt of the world—a globular chamber Ait 
walls, but destitute of any general aperture, the office of which 
is served by a series of Jarger pores scattered throughout the wall of 
the sphere. It has been maintained by some that ina is 
a detached generative ent of Globigerina, with which it 1s 


found associat pelea ey Mig aco hr 
assemblage of nearly spherical chambers (fig. 561), having coarsely 





Fro. 561.—Globigerina bullotiles ox sean in thivo positions. 


porous walls, and cohering externally into a more or less regular 
turbinoid spire, each turn of which consists of four chambers pro- 
gressively increasing in size, These chambers, whose total number 
seldom exceeds sixteen, may not communicate directly with ench 
other, bat open separately into a common ‘vestibule’ which occupies 
the centre of the under side of the spire. This type has recentl 

attracted great attention, from the extraordinary abundance in which 
it ocours at great depths over large areas of the ocean bottom. 
‘Thus its minute halls have been found to constitute no less than 
97 per cent. of the ‘ooze’ brought up from depths of from 1,260 to 
2,000 fathoms in the middle of the northern parts of the Atlantic 
Ocean. The younger shells, consisting of from eight to twelve 
chambers, are thin and smooth, but the older shells are thicker, 
their surface is raised into ridges that form a hexagonal areolation 
round the pores (fig. 562) ; and this thickening is shown by examina- 
tion of thin sections of the shell to Pe pennies, ‘by an exogenous 
deposit around the original ehamber-wall (corresponding with the 
“intermediate skeleton ' of the more complex types), which sometimes 
contains little flask-shaped cavities filled with sarcode—as was first 
pointed out by Dr. Wallich. But the sweeping of the upper waters 


746 MICROSCOPIC FORMS OF ANIMAL LIFE 


of the ocean by the ‘tow-net,’ which was systematically carried on 
a pepe rtcy brought into prominence the 
fact these waters in all but the coldest seas are inhabited by 
Jloating Globigerine, whose shells are beset with multitudes of de- 
licate caleareous spines, which extend themselves radially from the 
angles at which the ridges meet to a ‘equal to four or five 
times the diameter of the shell (fig. 563). the bases of these 

ines the sarcodic substance of the body exudes through the pores 

the shell, forming a flocculent fringe around it ; and this extends 





Fro, 562—Globigerina conglodata (Brady) : a,b, 0, bottom specimens; 
, section of abell. 


itself on each of the spines, creeping up one side to its extremity, 
and passing down the other with the peculiar flowing movement 
already described. The whole of this sarcodie extension is at once 
retracted if the cell which holds the Globigerina receives a sudden 
shock, or a drop of any irritating fluid is added to the water it con- 
tains. It is maintained by Sir Wyville Thomson that the bottom- 
deposit is formed by the continual ‘raining down ’ of the Globigerinse 
of the upper waters, which (he affirms) only five at or near the sur- 
face, and which, when they die, lose their spines and subside, The 


GLODIGERINIDA 747 


z 
= 


jor, however, from his own examination of the Globigerina ooze 
foot Beotog Sr euetyeute of Unis Rau? 
that if they have passed the earlier part of their lives in the 


4 
re 
3 
E 
f 


5 





tion having all the essential . 

characters of that genus. si lane eee pe bag eee dels 
Tt grows attached the 
apex of its spire, its later chambers increase ra in size, 
are piled on the earlier in such a manner as to form a depressed 
cone with an irregular spreading base. The essential character of 
geri the separate orifice of each of its chambers—is here re- 
‘ined with a curious modification ; for the central vestibule into 
i ed ap pe forms a sort of vent whose orifice is at the apex 
c is sometimes into a tube that proceeds 
from it; and the external of this cone is so marked out by 
septal bands that it comes to bear a strong resemblance toa minute 
Balanus (acorn-shel!), for which this type was at first mistaken. The 
principal chambers are partly divided into chamberlets by incomplete 
as we shall find to be in Zozodn, The presence of 
Sponge-spicules in large quantity in the chambers of many of the 
best examples a this type was for some time a source of 
; but this was explained by the late Professor Max 
who showed how nesnpicponie. of this rhizopod have 
the habit like those of Haliphysema of taking into themselves sponge- 
spicules, which they draw into the chambers, so that they become 
‘incorporated with the sarcode-body. It should be added that Pro- 
& Archiv f. Naturgeech. xxix. 1868, p. 81. 





ROTALIA 749 


po perk the spire, as shown in Plate XVII, fig. potas | 
and connections of the sexments of their sarcode-bodies being shown 

in such ‘ internal casts’ as are represented in fig. 564, B. Oneof the 
lowest and simplest forms of this type is that common one now 
di ed as Discorbina, The early form of Planorbulina ix a 

spire, Ee ee tof Discorbina ; but this 
afterwards gives cyclical plan of growth, ‘and in those 
most devel Tes de tis tone aMah oeece earners te 
cartier cham) are completely overgrown by the latter, which are 
often piled up in an lar ‘acervuline’ manner, over 
the nda of els or lstering ound the sta ot tes. 


eee the genus T'inoporus there 
regular growth of this wend, ¢ the 
Shenae being piled successively on 
es cae 
ani com- 
municating with each other obl Iv 
(like those of Tertularia) by 
apertures, whilst communicate 
with those directly al and below 
Le Pl ordinary pores of the shell. 
simple or son SMe of this 
genus formin, sul us Gypsina 
present: read Glveraition of shape, with ‘ 
great constancy in their internal struc- Fi. 565.—Tinoporws baculatue 
ture, being sometimes spherical, some- 
‘times resembling a minute sugar-loaf, and sometimes being irregu- 
larly flattened out. The typical form (fig. 565), in which tbe walls 
ee the piles are thickened at their meeting angles into solid columns 
that appear on the surface as tubercles, and are sometimes pro- 
longed into spinous outgrowths that radiate from the central mass, 
is of very common occurrence in shore-sands and shallow-water 
dredgings on some parts of the Australian coast and among the 
Polynesian islands, ‘To the simple form of this genus we are 
probably to refer many of the fossils of the Cretaceous and 
tar] jary period that have been described under the name 
Orbitolina, some of which attain a very large size. Globular Ovbi- 
tolin, which appear to have been artcaly perforated and strung 
as beads, Are not unfrequently found associated with the ‘ flint-imple- 
ments’ of Lawinen Another very curious modification of the 
bed eg resented by Polytrema, which so much resembles 
“esoedielad us to have been taken for a minute millepore, but which 
is made up of an ition of *Globigerine’ chambers communi- 
eating with each other like those of Tinoporus, and differs from that 
gents primarily in its erect and usually branching manner of growth 
and the freer communication between its chambers, ‘This, agnin, is 
‘of special interest in relation to ozodn, showing that an ein 
zoiphytic mode of growth is perfectly compatible with truly fora- 
miniferal structure. 
nae Rotalia, property 40 called, we find a marked advance towards 
the highest type of op iorahisalferel structure, the partitions that 








a 


FUSULINA — 7st 


errata vopeuigirenapmpree ee ae 
sept bat which inne of 

Sa termgsicmearticoon pene in Samer the 
axis of Le predgietonren joann Rennes beyond those of the 


jaineter.. Thus it 
ach attains 
Nummuline shell that Alecolina bears to ries ine 
of its affinities is full: omer lar aaibemereom 
nation of the structure, of ita shell, cere althou, he Pesala 


limestone of Russin has undergone a metamorphism, 
Lorry at nee emmengstepratien tam yr tan oe appear he 
prevent him from confidently affirming it, yet ces he 
could distinguish were decidedly in its favour. ving since 
received from Dr. C. A. MVLIG. specter tices tha, ope, Oual 
‘Measures of Iowa, U.S.A., which are in a much Sorinetoe state of 





Bio. 587.—Section of Fusulina limestone, 


ition, he is able to state with certainty, not only that Fusulinee 
is tubular, but that its tubulation is of the large course nature that 
marks its affinity rather to the Rofaline than to the Vununuline 
series. This type is of peculinr interest as having long been regarded 
a8 the oldest form of Foraminifera which was known to have occurred 
in sufficient abundance to form rocks by the aggregation of its in- 
dividuals. It will be presently shown, however, that in point both 
of erally. endo and of importance it is far surpassed by another. 
: the Arey eluboratel; constructed and the 
seat in Geoee thins vitreous’ Foraminifera belong to 
cc which the well-known Nummulite may be taken ye 
representative, Various plans of growth revail in the family ; 
but its distinguishing characters consist in the com 1 pagers of the 
wall that surrounds each segment of the body the septa being 
geome double instead of single), the density and fine porosity of 
shell-substance, and the presence of an ‘intermediate ees 


) 





POLYSTOMELLA 753 


we see that the segments of the sarcode-body are smooth along their 
anterior edge 6, b', but that slong their posterior edge, a, they are 
prolo lwekwards into a set of ‘ retral processes’; and these pro- 

ie under the ridges of the shell, whilst the shelly wall Ripe 
down into the spaces between them, so as to form the furrows seen 
on the surface. The connections of the segments by stolons, o, c!, 
Passing through the pores at the inner margin of each septum, are 
also admirably displayed in such ‘casts.’ But what they serve most 
beautifully to demonstrate is the canal system, of which the distri- 
bution is here most’ remarkably complete and symmetrical. At d, 
d', @® ave seen three turns of « spiral canal which passes along one 
end of all the segments of the like number of convolutions, whilst 
corresponding canal is found on the side which in the figure is under- 
most ; these two spires are connected by a set of meridional canals, 
¢,¢!, @, which pass down between the two layers of the septa that 





segments, and uniting themselves with the di ig branch 
diomal canals; @, @!, dl, three turns ef one of «piral canal ee, 
three of the meridional canals; f,/4,f%, their diverging branches, 


divide the segments; whilst from each of these there passes off 
towards the surface a set of pairs of diverging branches, 4) fs which 
open upon the surface along the two sides of each septal band, the 
external openings of those on its anterior margin being in the fur- 
rows between the retral processes of the next segment, These canals 
appear to be occupied in the living state by prolongations of the 
sarcode-body ; and the diverging branches of those of each convolu- 
tion unite themselves, when this is enclosed by another convolution, 


organischen Lebens;' in Adhanidtiingen der Konig. Akad. der Wissenschaften, 
Belin, YA55. It wassoon afterwards shown by the late Profensor Bailey (Quart, Journ. 
Micros. Sci, vol. ¥. 1887, p. 83) tHat the like infiltration occasionally takes place in 
recent Foraminifera, en: Jmilar "casts’ to be obtained from thet by the solu- 
tion of their whells im dil us Messrs, Parker and Rupert 
Jones, soon alterwanls complete internal caste from 
rwoent Foraminifera brought from va A nainber of Greensands yield« 
ing similar cats were collected on the ‘ Challenger ' Expedition, the most notable trom, 
the coast of Australia. 7 
° 








754, MICROSCOPIC FORMS OF ANIMAL LIFE 


with the stolon processes connecting the successive segments of the 
Jatter, as seen atc!, There can be little doubt that this remarkable 
development of the canal system has reference to the unusual amount 
of shell-substance which is deposited as an ‘intermediate skeleton’ 
upon the layer that forms the proper walls of the chambers, and 





Fro, 669,—Cycloclypens—external warface and vertical and horizontal sections. 


which fills up with « solid ‘boss’ what would otherwise be the de- 
pression at the umbilicus of the spire. The substance of this ‘ boss ' 
is traversed by a set of straight canals, which pass directly from the 
spiral canal beneath, towards the external surface, where they open 
in little pits, as is ‘chown in Plate XVII, 23, the umbilical boss 

in P. crispa, however, being much smaller in proportion Bie it it 





Fro, £70-—Opercutina lnid open te show its internal stencture ; a, marginal 
cord een in 3, d, external walla of the chau 


€.¢, cavities of the see, thelr alar prolougntions; dy 4 

at id and at d™ wo. ns, (0 Jay epam tbe Jal terseptal canals, = 
general distribution of which is seon in the sept ¢, 6; the lines radiating 
from ¢, ¢ point to thy secondary pores; g, 9, non-bubslar columne. 





is in P. craticulata, There is a group of Foraminifera to which the 
term .Vonionina is properly applicable, that is probably to be con- 

sidered as asub-genus of Polystomella, agreeing with it in its general 
conformation, and especially in the distribution of its canal system, 
but differing in its aperture, which is here @ single fissure at the 
inner edge of the septal plane, and in the absence of the ‘retral pro- 


NUMMULINE FORAMINIFERA 755 







the segments of the sarcode-body, the external walls of 
ibers being smooth. This form constitutes 2 transition to 
Nummuline type, of which Polystomelia isa more aber- 
‘on. 


‘Nummuline type is most claracteristically represented at the 
Etime by the genus Opereulina, which is s0 intimately united 
true Vummulite by intermediate forms that it is not easy to 

the two, notwithstanding that their typical examples are 
dissimilar. The former genus (fig. 570) is represented on our 
and in northern seas by very small and feeble forms, but 
a much higher development in the tropics, where its 
sometimes reaches one-fourth of an inch. The shell is a 
nautiloid spire, the breadth of whose earlier convolutions 
in a regular progression, but of which the last convolution 
m specimens) usually flattens itself out like that of 

so as to be very much broader than the preceding. The 
walls of the chambers, arching over the spaces between the 
are seen at b,/; and these are bounded at the outer edge of 










laid open to show its internal structure : a, chambered 
skeleton ; ¢, one of the radiating prolongutions 
a it, with extensions of the canal-system, 


luy @ peculiar band, «, termed the ‘marginal cord.’ 
of being perforated by minute tubuli like those 
the inner to the outer surface of the chamber-walls 
or inosculation (fig. 574), is traversed by a system 
ly large inosculating passages seen in cross-section at 
these form part of the canal system to be presently de- 
The principal cavities of thé chambers are seen at ¢, ¢ ; 
r prolongations’ of those cavities over the surface of 
‘preceding whorl are shown at c’, c’. Thechambers are separated 
septa, d, d, d, formed of two lamina of shell, one belonging 
peach chamber, and having spaces between them in which lie the 
canals,’ whose general distribution is scen in the septa 

irked ¢, ¢, and whose smaller branches are seen irregularly divided 
t the eerie d’, whilst in the septum d” one of the principal 
aks is laid open through its whole length. At the approach of 
teh septum to the marginal cord of the preceding is seen the 
wrow fissure which constitutes the principal aperture of communi- 







B02 


of Europe and Africa, through Western Asia to Northern India and 
China, and tbe over vast ares ct a ee (fig. 572). 
The diameter of a large prepare fossil Nummulites ranges 
etwas half an inch an inch; but there are some whose 
diameter does not exceed 4';th of an inch, whilst others attain the 
gigantic diameter of 44 i ‘Their form is that of a 


double-convex Jens ; but sometimes it much more 

the globular shape, whilst in other cases it is sie Saag 
and great differences exist in this respect among individuals of what 
must. be accounted one and the same species. Although there are- 
some Nummulites which closely approximate Opercuime in their 
mode of growth, yet the typical forms of this genus present certain 
walsugnel distinctive peculiarities, Each convolution is so com- 
pletely invested by that which succeeds it, and the external wall or 
spiral lamina of the new convolution is so from 
that of the convolution it encloses by the ‘alar ions’ of its 
own chambers (the peculiar ee pares which will be presently 
described), that the spire is scarcely if at all visible on the external 
surface. It is brought into view, however, by splitting the Num- 
mulite through the median plane, which may often be accom- 
plished simply by striking it on one edge, with a hammer, thé opposite 


NUMMULITES 757 





laced on a firm support ; or, if this method should not 
‘by heating it in the flame of a spirit-lamp, and then throw- 
cold water or striking it edgeways. Nummulites usually 
more turns, and a more gradual rate of increase in the 
the spire, than Foraminifera generally : this will be appa- 
an examination of the vertical section shown in tig. 573, 
is taken from one of the commonest and most characteristic 
















Fia. 572.—A, piece of Nummutitic limestone from Pyrenees, 
showing Nommulites laid open by fracture through’ median 
plane ; B, Orbitoides. 


pples of the genus, and which shows no fewer than ten convo- 
in a fragment that does not nearly extend to the centre of the 
This section also shows the complete inclosure of the older 
ions by the newer, and the interposition of the alar prolonga- 
of the chambers between the successive layers of the spiral 
These prolongations are variously arranged in different 





Mio, 578.—Vertical section of portion of Nummulites levigata: a, margin 
of external whorl ; d, one of the outer row of chambers; ¢, ¢, whorl invested 
by a: d, one of the chambers of the fourth whorl from the margin ; ¢, ¢’, 
marginal portions of the incloxed whorls; f, investing portions of outer 
whorl; 9, 9, spacer left between the investing portion of successive whorls ; 
A,k, sections of the partitions dividing these. 


tamples of the genus: thus in some, as Y. distuns, they keep their 
mm separate course, all tending radially towards the centre ; in 
Y, levigata, their partitions inosculate with ench other, so 
to divide the space intervening between each layer and the next 
to an irregular network, presenting in vertical section the appear- 
ce shown in fig. 573 ; whilst in .V. gerensensis they are broken 


758 MICROSCOPIC FORMS OF ANIMAL LIFE 


into iber of chamberlets having little oF no direet commani- 
eatlog with each other, bergen 
naalieneamea ‘that the inner chambers are thus 


N 50° 
in the mass of investing whorls, yet there is evidence: 





ca tee 


tnd 
pillars of solid wubstanoe not perforated by tubal 


the segments of sarcode which they contained were not cut off from 
communication with the exterior, but that they may have retained 


their pay to the cect The sy ie is almost as 
hi inutel vous, being penetrat ‘tubuli, w! 
Pauw directly beenoes parhise! to the other. Jeera 
as divided Jengthwise by a vertical section, in tig. 574, a, 5 whilst 
the appearance they present when cut across in 11 horizontal section 
ia j 


e 





Fio, 875 —Portion of horizontal section of is shown by horizontal sections 


M lifes showing the #tracture of the ‘communicate | 
wea, and of the septa of tha. chaunbonss bar freoly 


wering o wit other laterally, so 
Slaabech ta puactaltsea cl eh oe en aki such as 


a 
orifices of tubali; bb, septa between thew ix sean nt b, b, fig. O76, At 
intent tranches of, cmering the counters certain other points, «, dd, 


by Innger oritices, ono of which ikseenat d. fig. S74, the shell-substance 
is not perforated by tubes, bat 

is peculiarly dense in its texture, ori solid which seem 
to strengthen the other parts ; and in Nummulites whose surfaces: 
have been much exposed to attrition, it commonly happens that the 
pillars of the superficial layer, being harder than the “shell- 
substance, and being consequently less worn down, are left ms 


a 


NUMMULITES 759 
prominences, the presence of which has often been accounted (but 


tine asa specific character, The successive chambers of the 
same communicate with each other by a passage left between 
eee ieomte ase dion pps 


peal nypealbor iro 
sie ue 
a large broad 
aperture, but is more com- 
monly formed by the more or 
less ‘complete coalescence of 
several separate perforations, 
po roa mba 
is as in a 
variable number of isolated 
in most of the septa, 
‘ing a secondary means of 
communication between the 

chambers, The canal 3} 


; 


i 





ill generally jose traces of 

the partitions that divide the chambers (fig. 575, é i “bile from 
these may be seen to proceed the Siena Eee which, after 
rowing (so to speak) in the walls of the chambers, enter them 

oSoredtde ‘These ‘interseptal ' canals, and their communi~ 
cation with the inosculating system of passages excavated in the 
marginal cord, are extremely 
well seen in the ‘internal cast’ 
in fig. 576, 


ee 


resent in the genus 
Heterostegina (fg. 577), which 
bears avery strong resemblance 
to Orbiculina in its plan of 
nowt whilst in other 
it is essentially dif- 
ferent. If the principal cham- 
of an ina were 
divided into chamberlets by 
secondary partitions in a direc- 
tion transverse ea eet ine 
Principal septa, it wi Fro. 877.—Heterostegina, 
converted into a Z/eterostegina, sp 
just as a Peneroplis would be converted by the like subdivision into 
an Orbiculina, Moreover, we see in Heterosteyina, as in Orbieulina, 
‘a great tendency to the opening out of the spire with the advance of 


i 








760. MICROSCOPIC FORMS OF ANIMAL MFE 


curious that we have in this series another form, 
bears exactly the same relation to beat aorviepeornss does 
to Orbieulina, in constructed upon the eyelieal plan from the 


the recent condition by at con — 
eens eee Bae of ee ee aaa r 

ic, is exi Foraminifera, some speci- 
mens of ita eae the jitiah Mase having a diameter ot two 
and a quarter inches, Notwithstanding the difference of its plan 





1a, S78,—Hooti Orbitoider intervening spaces ; and are all 
Fie rtath, parallel Pe the S| traversed by columns of eoreaie 


teen nd sha thewnpertcial gulstance, which spring from the 


: and ually increase 
ty in diameter with pte “s to 
the surface, from which they project in the central of the 


disc nx glistening tubercles, 

The Nummulitic limestone of certain localities (as the south-west 
of France, Southern Germany, North-eastern India, &e.) contains a 
vast abundance of discoidal bodies termed Orbitoides (fig. 572, B), 
which are so similar to Nummulites as to have been taken for them, 
but which bear a much closer resemblance to C; 
are only known in the fossil state; and their structure ean only be 
ascertained by the examination of sections thin enough to be trans- 
lucent. When one of these dises (which vary in size, in different 
species, from that of a fourpenny-piece to that of half a crown or 
even larger) is rabbed down so as to display its internal organisation, 
two different kinds of structure are usually seen in it, one being 
composed of chamberlets of very definite form, quadrangular in some 


ORBITOIDES: 761 


iroular in with but not constant 
knrne in pesbnetrnaghsie 7 378, aa the other, less. 
transparent, being formed of minuter chamberlets which have no 
such constancy of. 


form, but which might almost be taken for the 





SECA SACS CS aaa 


Gr nr pap yg rn gene 
coveted above and below by the superfical layers. ‘3 

evident by the examination of a vertical section (fig. 580), which 
shows that the portion 4, figs. 578, 579, forms the median plane, 
its concentric circles of chamberlets being arranged round a | 
central chamber, as in Cycloclypens; whilst the chamberlets of the 
portion « are irregularly Superpossl one 
upon the other, so as to several 
layers which are most numerous towards 
the centre of the disc, and thin away 
gradually towards its margin. ‘The dis- 

‘ition and connections of the cham- 

lets of the median layer in Orbitoides 
seem to correspond very closely with 
posers poenemeuente described Reema ade es 
as iling in Cyeloelypeus, the most (eynege oe mete! 
ftistactory indications. to this etfect bor hey Paya ati 23 
being furnished by the silicious ‘internal @.9, a°a, 0a", six chatubers 
casts’ to be met with in certain Green- tf _eaeh of three sanes, with, 
sands, which afford a model of the sar- find at bb.0' 0 0° 2", portions 
cotle-body of oe ee In deere of three annular eanals, 
fragment (fig. 581) we recognise the 
Sie es three successive zones, a, a’, a’, each of which 
seems normally to communicate by one or two passages with the 
chamberlets of the zone internal and external to its own; whilst 
between the chamberlets of the same zone there seems to be no direct, 





762 MICROSCOPIC FORMS OF ANIMAL LIFE 
connection. They are brought into relation, however, by means 
of annular canals, which seem to represent the spiral canals of the 
Hep and of which the ‘internal casts’ are seen at b b, bi U/, 
sal 2 

A most remarkable fossil, referable to the foraminiferal type, 
hs been recently discovered in strata much older than the very 
earliest that were previously known to contain organic remains ¢ 
and the determination of its real character may be regarded as one 
of the most interesting results of microscopic research. This fossil, 
which has received the name Fozodn canadenae (fig. $82), is found 
in beds of Serpentine limestone that occur near the base of the 





Pro, 





Vertical section of Haacim cawatdenas sowing alteration ot 
calcareous (light) and serpentinoun (dark) lamella, . + 


Laurentian formation of Canada, which has its parallel in Europe in 
the ‘fundamental gneiss' of Bohemia and Bavaria, and in the 
earliest stratified rocks of Scandinavia and Scotland. These 

are found in many parts to contain masses of considerable size, bat 
usually of indeterminate form, disposed after the manner of an 
ancient coral reef, and consisting of alternating layers—frequently 
numbering from 50 to 100—of carbonate of Sis and 

(silicate of in a). The regularity of this alternation and the 
fact that it presents itself also between other calcareous and silicious 
minerals having led to a suspicion that it had its origin in organic 
structure, thin sections of well-preserved specimens were submitted 
to microscopic examination by Dr. (now Sir W.) Dawson, of Mon- 









EOZOON 763 


at once recognised its foraminiferal nature,! the calca- 
8 presenting the characteristic appearances of true xhel/, 80 
to form an irregularly chambered structure, and frequently 
»y systems of ramifying canals corresponding to those of 
3 whilst the serpentinous or other silicious layers were 
vy him as having been formed by the infiltration of sili- 
lution into the cavities originally occupied by the sarcode- 
e animal—a process of whose occurrence at various geo- 
iods, and also at the present time, abundant evidence has 
en adduced. Having himself tuken up the investigation 
ance of Sir William 1), the Author was not only able 
t Dr. Dawson's conclusions, but to adduce new and im- 
‘idence in support of them.?’ Although this determination 
walled in question, on the ground that some resemblance tu 
. Organic structure of Eozoin is presented by bodies of 
origin,? yet, as it has been accepted not only by most 
knowledge of foraminiferal structure gives weight to 
Cemong:yhow the late Professor Max Schultze may 
), but also by geologists who have specially 
mineralogical structure of the older Metamorphic 
feels justified in here describing Eozodn as 
‘to-have existed when it originally extended itself as 
over vast areas of the sea-bottom in the Laurentian 









tially belonging to the Nummuline group, in virtue 
of the shelly layers forming the ‘proper wall” 
ges, Eozoin is related to various types of recent Fora- 
Wits other characters. For in its indeterminate zoéphytic 
(Rowth it agrees with Polytrema in the incomplete separa- 
Yehambers ; it has its parallel in Curpenteria ; whilst in the 
t of its ‘intermediate skeleton’ and of the ‘canal 
wy which this is formed and nourished, it finds its nearest 
ative in Calearina. Its calcareous layers were +o super- 
@ upon another as to include between them a succession 


‘wcognition was due, as Dr. Dawson hax explicitly stated in his original 
tart. Journ. of Geol. Soc. vol. xxi. p. 54), to his acquaintance, not merely 
uthor’s previous researches on the minute structure of the Foraminifera, 
especial charactera presented by thin sections of Calcarina which hud 
Sitled £6 Kim by the Author, ‘Dr. Deveson lise given ior account of tre 
nd mineralogical relations of Eozcin, as well as of its orgunic structure, in 
kentitled The Dawn of Life. 
faller account of the results of the Author's own study of Eozciin, und of the 
lich the above reconstruction ix founded, wee hix papers in Quart, Journ. 
2. vol. xxi. p. 59, and vol. xxii. p. 210, and in the Jutellectual Ohser 
5, p. 278; and hin Farther Researchen’ in Any. of Ne 
2 memoirs of Professors King and Rowney in Quart. Journ. of Geol. Suc. 
185, and Ann. of Nat. Hist, May 1871. 
4 these the Author is permitted to mention Professor ( 
Isstudied the older rocks of Scotland, and Professor Boni 
like study of the Cornish und other Serpentine: se eminent 
he ix ansured that they have met with no pur ral strneture in the 
bling Fuzo‘n, either in its regular alternation of calcareous and serpen- 
le, of in the dendritic extensions of the latter into the former; and while 
ta entirely watisfnctory the doctrine of ity ongaaie origin maintained by 
find themselves unable to conceive of uny inorganic agency by whiel 
cture could have been produced. 
















ie, of Edinburgh, 
lon, who 

















764 ‘MICROSCOPIC FORMS OP ANIMAL LIFE 


storeys’ of chanbers “Al, A, At, AY), the chambers 
pyar loeeettatenor La Pav oh a ecan ie 





chambers of lower storey ‘into < 
occasion: n 
Ae ee sary, B, 085), bearing ‘a singe- 
proper walls of the. chambers formed ol a 8 

file Slimane igen win 

that: Ww. 
lon-passages, D, connecting the ot bs 
Iiherenesoreys und penetra by themes The thickness of this 
cont ayatems of canals, E, E, E. int layer varies 
of the bei val ae i 

ent parts same mass, being in general greatest near ite 
base and progressively diminishing towards eee! surface, 
The ‘intermediate skeleton’ is occasionally tra by 
passages (D), which seem to establish a connection between 
successive layers of chambers; and it is ted by arborescent 
systems of canals (E, E), which are distributed both *0 
extensively and so minutely th its substance as to leave 
very little of it without « branch. ese canals take their origin, 
not directly from the chambers, but from irregular acum oF 
interspaces between the outside of the proper chamber-walls and 
the ‘intermediate skeleton,’ exactly as in Calearina, the exten- 
sions of the sarcode-body which occupied them lm ay 
been formed by the pace les of the pseudopodial that 
passed through the tubulated lamella. 


| 


ROZOON 755 
fossilised condition in which Zozoiin is most commonly 


tee 
nui 

He 
fF 
1H 
abe 
Fe 
al 
ie 


He 
ie 
EPy 
i 
ze 

i a 
i 
E 

A 


in hard cee of ‘body 
pied the cham! and extended itself into the ramifyi 
of the calcareous shell ; and, like that of Polystomella, it atfords an 
even more satisfactory elucidation of the relations of these parts 
than we could have gained from the study of the living organism. 





Fro. 584.—Deoaloified portion of Eoroin eanadense shell, showing the ser- 
pentinous internal cast of the chainbers, canals, and tubuli of the inal, 
Hecsenting an exact mode of the animal sabstanco which originally 


We see that each of the layers of serpentine, forming the lower part 
of such a specimen, is made up of a number of coherent segments, 
which have only undergone a partial separation ; these appear to 
have extended themselves horizontally without any detinite limit ; 
but have here and there developed new segments in a vertical direc- 
tion, 50 ns to give origin to new layers. In the spaces between these 
successive layers, which were originally occupied by the caleareous 
shell, we see the ‘internal casts’ of the branching canal system, 
which give us the exact models of the extensions of the sarcode-body 
that originally passed intothem. But this is notatl, In specimens 
in which the Nummuline layer constituting the ‘proper wall” of the 
chambers was originally well preserved, and in which the decalcifying 
process has been carefully managed (so as not, by too rapid an evolu- 
tion of carbonic acid gas, to disturb the arrangement of the serpen- 
tinows residuum), that layer is represented by a thin white film 
covering the exposed surfaces of the segments ; the superficial aspect 





more definite plan. After what fashion the er/iest development of 
Eozoiin took na have eb: prosendiosknne ledge ualerio ee 

i recently discovered itis obvious 
that each successive ‘storey ’ of chambers was limited by the closing 
in of the shelly at its edges, so as to give to the entire fabric a 
definite form closely resembling that of a strai ed Peneroplis. 
‘Thus it fotos that the chief peceliriiy ot marie in its 
eapacit i nite extension, 50 product of a si germ 
Sipiteitais a Mancarnpaciie daptat ahateonctrooeals ‘ow this, 
it will be observed, is simply due to the fact that its increase by 
mation takes place continuously, the new segments successively 
off remaining in connection with the original stock, instead 
of detaching themselves from it, as in Foraminifera generally. Thus 
pase lobe ine forms a shell of which the nam| ofan ees 

not usually seem to increase beyond sixteen, any additic 

eeearin menn iecel ay Be ester areata aE but by 
repetition of thix multiplication the sea-bottom of large areas of 
the Atlantic Ocean at the present time has come to be covered with 
accumulations of Globigerine, which, if fossilised, would form beds of 
limestone not less massive than those which have had their origin in 
The difference between the two of 
increase may be compared to the difference between a herb and « 
tree. For in the herb the individual ism never attains 
considerable size, its extension by being limited Shot 
the aggregation of individuals produced by the detachmentof its buds 
ape eats Geld eariatve Beet mass of vegetation as great. 
aoe in the largest tree by the continuous putting forth of 
new 


Tt has been hitherto only in the Laurentian serpentine lime- 
stone of Canada that Hozodn has presented itself in such a state of 
inno ns fully to justify the assumption of its organic nature. 

ut from the greater or less resemblance which is presented to this 
serpentine limestones occurring in various localities among strata 
seem the geological equivalents of the Canadian Laurentians, it 
seems a ustifiable conch that this type was generally dif- 
fused in the earlier ages of the earth's , and that it had » 
Iarge (and probably the chief) share in the production of the most 
ancient calcareous strata, separating carbonate of lime from its solu- 
‘tion in ocean water, in the same manner as do the polypes by whose 
growth coral reefs and islands are being Ly Sarin at the present time. 

An elaborate work, ‘Der Bau des Eozotin Canadense’ (1878) 
has been recently penne by Professor Mobius, of Kiel, in which 
the structure of Zvzodn is compared with that of various types of 
Foraminifera, and, as it differs from that of every one of therm, is 
afirmed not to be organic at all, but purely mineral, Upon this the 
Author would remark, that if the validity of this mode of reasoning 
beadmitted, any fossil whose structure does not correspond with that: 
‘of some existing type is to be similarly rejected. Thus the Stroma- 
topora of Silurian and Devonian rocks, which some palwontologists 

as a coral, others as pol: , others as a calcareous sponge, 
others as foraminifer, would not be a fossil at all, because it differs 


FH 


f 


F 
5 
j 





COLLECTING FORAMINIFERA 769 


m and Selection of Foraminifera.—Many of the Fora- 
tach themselvesin the living state to sea-weeds, zoéphytes, 
they should therefore be carefully looked for on such 

ly when ‘it is desired to observe their internal organ- 
their habits of life. They are often to be collected it 
numbers, however, from the sand or mud dredged up 

‘bottom, or even from that taken from between the tide- 

@ paper containing some valuable hints on this subject ' 
Mentions that, in walking over the Small-mouth Sand, 

is situated on the north side of Portland Bay, he observed 
t© be distinctly marked with white ridges, many yards 
running yerallel with the edge of the water ; and upon 

ions of these, he found Foraminifera in considerable 

‘One of the most fertile sources of supply that our own 

dl is the poze of the oyster-beds, in which large numbers 

will be found ; the variety of specific forms, how- 

great. In separating these bodies from the 

&e. with which they are mixed, various 

be adopted in order to shorten the tedious labour of 

out one by one under the simple microscope ; and the 

6 be made among these will mainly depend upon the condi- 
if the Foraminifera, the im ce (or of erwe) of obtaining 
ali and the nature of the substances with which they are 


le if it be desired to obtain living specimens from the 


the examination of their soft parts, or for preservation 

uarium, much time will be saved by stirring the mud (which 

be taken from the surface only of the deposit) in a jar with 

jand then allowing it to for a few moments; for the 

particles will remain diffused through the liquid, while the 

will subside ; and, as the Foraminifera (in the present case) 

We among the /eavier, they will be found at the bottom of the 

‘with comparatively little extraneous matter, after this opera- 

Aas been repeated two or three times. It would always be well 

ine the first deposit let fall by the water that has been 

d «way, as this may -contain-the smaller and lighter forms of 

Rininifera. But supposing'that it be only desired to obtain the 

fshells from a mass of sand brought up by the dredge, a very 

mt method should be adopted. The whole mass should be 

ed for some hours to the heat of an oven, and be turned over 

times, until it is found to have been thoroughly dried 

shout ; and then, after being allowed to cool, it should be 

in a large vessel of water. The chambers of their shells 

now occupied by air alone (for the bodies of such as were 

% will have shrunk up almost to nothing), the Foraminifera will 

the lightest portion of the mass ; and they will be found floating 

be water, while the particles of sand &c. subside. Another 

thed, devised by Mr. Legs, consists in taking advantage of the 

[tive sizes of ditierent kinds of Foraminifera and of the substances 

accompany them. This, which is especially applicable to the 

(Land rubbish obtainable from sponges (which may be got in 
¥ Trans. of Micros. Soc. ser. ii. vol. ii. 1854, p. 19. 











feeds on the waste of the animal. - 

In most Rardiolaria skeletal aes de in the 
sarcode-body, either inside itsicle the capsul in 
soosskines te the form of be: : 
investingnetworkshaving 


of ir many asa Chee 
zovids, aggregated toge- 
ther in various forms, dise- 
Gidal, chain-like, « . 
in-like, OF even” pi, $98-—P 2 focyrtis 
necklace-like, The ‘colo- Leas niicrerty Bh et poor seats 


3 





nies’ seem to be produced, 
like the mip segments of the bodies of Foraminifera, by the 
non-sexual multiplication of a primordial zoid ; but whether this 


multiplication takes place by fission, or by the budding off of 
tions of eels oe has not bathe ay ade ou re he 
emission zoospores, provided with a very nucleus, 
and in some cases with a Pallike orpetal has been observed in many 
radiolarians ; but of the mode in which they are produced, and of 
their subsequent history, very little is at present known. Until the 
structure and life-hi of the animals of this very interesting type 
shall have been more fully elucidated, no satisfactory classification 
‘of them can be framed ; and nothing more will be here attempted 
than to indicate some of the principal forms under which the radio- 
larian type presents itself.? 

+ Bee Brandt, Verhanal. Physiol. Gesetlsch, Berlin, 1881-82, p. 22; 
Milk Boot Seat feta iv. p. 191; P. Geddes, bape 3 Pee) 


7 Considerable attention has been. yiven to the question of the classification of 
the Radiotaria by Hasckel and by 1 Hertwig, Jenaische Denkschr. ii 1879, p. 129, 























RADIOLARIA 775 


Fro. 500-—Vurietal modifications of Astromma: 





& eross with equal arms ; whilst in F and G it still shows 
. jicnously, though the spaces between the rays are in 
Ppart filled up by the circumferential network. Tn the five-rayed 
as A and B, on the other hand, the radial portion is mach 


BL —Perichlamydinm prateztiom, Fie, 602. Styiodyetywe gracilix, 


o 1 nore discoidal. 
@ in © and E, while the circumferential network forms a penta- 
ise, the radial portion is representeil only by solid projections 
teangies, The transition between the extreme forms is found 





tomostraca, 
Pheodaria.—. the most. important of the Radiolaria 
collected CI aeeicach tec pol camer armas ace 
1mm. in diameter) single-celled forms which are remarkable for the 


constant of dark brown granules, which are scattered 





fealialartat typain their Pio. BM —Spherozoum ovodimare. 
eiinal, eed 


are 

into masses in which the skeleton is ted only 

by scattered spicules, as in Spherosown (fig. 594) and Thalassicolla. 
*sea-jellies,’ which so abound in the seas of warm latitudes as 

to be among the commonest objects collected hy the tow-net, are 
small gelatinous rounded bodies, of very variable size and shape, 
but usually either globular or discoidal. Externally they are invested 
by » layer of condensed sarcode, which sends forth pseudopodial 
ions that commonly stand out like rays, but sometimes inoseu- 

late with each other so as to form a network, Towards the inner 
surface of this coat are scattered a great number of oval bodies 
resembling cells having a tolerably distinct membraniform wall and 
a conspicuous round central nucleus, Each of these bodies appears 
to be without any direct connection with the rest, but it serves 
as a centre round which a number of minute yellowish-green 
vesicles are disposed. Ench of these groups is protected by a 


779 ‘ 


CHAPTER XV 


SPONGES AND ZOOPHYTES 


T. Sponges. 


leave the Protozoa and commence the study of the MeTazoa, 
‘orms in which the egg-cell undergoes subdivision, the result- 
ents of which do not separate or lead an independent 
, bat combine to form an organic whole, various parts 
ing various functions. Of these Metazoa the simplest ex- 
re to be found among Sponces. The determination of the 
seter of the animals of this class has been entirely effected by 

ic examination of their minute structure ; for until this 
be properly understood, not only was the general nature of 
anisms entirely misapprehended, but they were regarded 
naturalists as having no certain claim to a placé in the 
ingdom. What that place is, is, to some extent, still an 
ation, but it may now be unhesitatingly affirmed that a 
san aggregate of protozoic units, only in the sense in which 
toa are composed of cells ; some of these cells have a striking 
nee to the collared Flayellata (fig. 527), whilst others re- 
A4meebee (fg. 519). ‘These units are held together by a con- 
connective-tissue-like substance which clothes the skeletal 
wrk that represents our usual idea of a sponge, and is itself 
p of distinct cellular elements. In the simpler forms of 
however, this framework is altogether absent ; in others it 
sented only by calcareous or silicious ‘ spicules,’ which are 
d through the sarcodic substance (tig. 596, B) ; in others, 
he skeleton is a keratose (horny) network, which may be 
destitute (as in our ordinary sponge) of any mineral support, 
ch is often strengthened by calcareous or silicious spicules 
i); whilst in what may be regarded as the highest types of 
1p, the silicious component of the skeleton increases, and the 
2 diminishes until the skeleton consists of a beautiful silicious 
¢ resembling spun glass, But whatever may be the condi- 
the skeleton, that of the body that clothes it remains 
lly the same ; and the peculiarity that chiefly distinguishes 
nge-colony from the plant-like colonies of the flagellate 
a is that whilst the latter extend themselves oufwards by 
| ramification, sending their zodid-bearing branches to 





certain globular clusters are di: scene 
ihe dc leanl gobs Speed this cat 
(pee eats Thus is formed one of the characteristic ‘ampul- 
sacs,” which, at first closed, afterwards communicates with 
the exterior, on the one hand, by an incurrent passage, and on the 
ins tobe eee re hg i ge apt Al Meee Be- 
sides this reproduction by ‘ microspores,’ is another form 
‘of non-sexual reproduction by macrospores, which are clusters of 
am capsules, frequently strengthened on 


ampullaceous sacs is really, like the system of canals in the sponge- 
like Alcyonium, an extension of the primitive gustric cavity, the 
osculee ee being the undeveloped representatives of the 
ie 

arrangement of the keratose reticulation in the 

which we are most familiar may be best made out by cutting thin 
slices of m piece of Sponge submitted to firm Cen Weegee and view- 

Mies nines upon a dark ground, with a low ifyi 

power under incident light. Such sections, thus illuminated, are 
not morely striking objects, but serve to show, very characteristically, 
general disposition of the lai canals and of the smaller pores 
with which they communicate. In the ordinary sponge the fibrous 
skeleton is almost entirely destitute of spicules, the absence of 
which, in fact, is one im) wnt condition of that flexibility and 
compressibility on which its uses depend, When spicules exist in 
connection with such a skeleton, they are usually either altogether 


é 


F 


1 See Chapter V. of Mr. Saville Kent's Manwal of the Infusoria, and V.of 
vol. of Mr. Balfour's Comparative Embryology, as well as Professor I's im- 
Portant work on the Calcareous Sponges. 








06.—A, section through Phakellia seniiiareny. TH, comnerida, taken at eight 





les to the surface, to show the arrangement of the parts of & Fs 

om the aurlace leading to ée, the inhalent eanals, then to the eteclned tier 
fe, and thence to the exhalent canal, ¢c, to 0, the scuba —— 
‘dm. B, more highly magnified view ‘of the internal portion 

Azinelia paradora * 290: we, meredermal cella. Other letters as in A. 

Ridley and Dendy.) 





SPONGE-SPICULES 783 


netimes pointed at both ends, sometimes at one only ; 
a ends may be furnished with a head like that of a 
carry three or more diverging points which sometimes 
30 as to form hooks. When the spicules project from the 
:work they are usually somewhat conical in form, and 
ris often beset with little spines arranged at regular inter- 
them a jointed appearance.' The more recent authorities 
such as Professor Sollas and Messrs. Ridley and Dendy, 
sed that in the present state of our knowledge the spicules 
rdinarily found in silicious Sponges belong to one of two 
ch, as they differ considerably in size, may be called 
(or, more correctly, megaloscleres) and microscleres. Itis 
te arrangement of the former that, with or without the 
spongin, the sponge owes its definite skeleton ; the micro- 
consistency to the 


andare ir- - 
attered throughout te’ 
e. If we desire to at” 
hysiological names 7 
| the megaloscleres at 
ules, and the micro- 


i-spicules. If we 
ind that in the 
he most competent 
s the polyaxial 
the most primi- 

is no_ practical 
our noticing them 
se order ; a method 
e found to conduce 
ty of description. 
ination of spicules, 
ary, first of all, to 
between axes and 
in the Monaxonida 


seleres have but wo son. Strvetiny of tha shel tM 
rowth F%9- 597.—Structure of the chele of Mo- 
but the growth “‘hxonid Sponges: 1, tridentate anisochele 
oint of origin may from in front; 1a, from the side; 2, 2a, 
er side, when we front oa: wide ‘views of a palmate isochela; 
: »  dincti ,t, tubercle; at, ut’, anterior tooth or 
ayed or diactinal join. Zt 1, lateral tooth or palm; shafts 
es, oritmayextend — f, fimbria. (After Ridley and Dendy.) 
tion only, when the 
said to be monuctinal. In the Calcispongiw there are 
and three rays; but in some sponges, such as Venus’ 











+ account of the various forms of spicules contained in Sponges is given 
tbank in his first memoir ‘On the Anatomy and Physiology of the 
a. Phil. Travs. 1858, pp. 279-882; and in hix Monograph of the 
fiada, published by ‘the Ray Society. ‘The Calcareous Sponges have 
Professor Haeckel the subject of an elaborate monograph, Die Kalk- 
arlin, 1472. For compendious enumerations and classifications of the 
of spicules, wee Professor Sollas, art. ‘Sponges,’ in Encycl. Britannica, 
idley aud Dendy, Report on the ‘Challenger’ Mcnazonida, pp. xv-xxi. 




















fis 
Boks 
iy 
ae 
re 
5.50% 
1 { 
tH 
et 
Ge 


te 
le 
+ 
i 
i 

i 
Fé 
in 


‘ 
i 
a 
! 
u 


: 
i 
i 
E 
; 





massive than that of Euplectella, but it is not so exch 
mineral ; oe it pe a 


“| 
i 
al 
ne 
a 
eal 


‘ easamablance te Se bi sieceay en abate Oat 
shyevelgations, weve show itis jiffused, 

and it is only one of several deep-sea forms iin 

of pegalecly beautiful structure, which are the 

sentatives of the old ventriculite type. One of ep was. ne 

known from ie cast upon the shore of 

after a storm, This Dietyoralyx pumiceus has the ‘of a mush- 

room, the diameter of its disc sometimes ranging to a Asmall 

portion of its reticulated skeleton is a singularly beautiful Liohsiet 
when viewed with incident light under a low magnifyi 


tying power. 

the exception of genus Spongilla and its allies, all 

known sponges are marine, but they differ much in habit of 
For whilst some can only i obtained by dredging at con- 

siderable depths, others live near the surface, whilst others attach 

peti to the surfaces of rocks, shells, ce. between the tide~ 

marks. The various species of Gruntia in Vetee of al} the marine 


ete 


meet flagellate cells can en bserved, belong to 
mcweuney- They have a eae ple structure, each 
bag whose wall ix so Pci th thee no system of cannls is 


i 


|, the water absorbed by the outer surface passing directly 
towards the i inner, and elnauespeled by the mouth of the bag. The 
Hagella may be plainly distingui with a j-ineh objective on some 
of the cells of the gelatinous substance scraped from the interior of 
the bag ; or they may be seen in site by making very thin trans- 

verse sections of the substance of the sponge. It is by such sections 
aed that the internal structure of sponges, and the relation of 
their spicular ane power skeletons to r fleshy substance, can be, 
demonstrated. They are best made by the imbedding process. In 


ent of the soft parta of Euplectelia aspergilivm have 
tan ay neste er aakalea teams opal don ae Baath aie 


PeNGae his elaborate memoit ia Pik ‘Trans. 1670, aa hin Deptha of the Sea; 
1874, p, TL 
de 


C@ELENTERATA 787 


modes, In the first place, the digestive sac is observed 
. by a layer of ameboid cells, which send out pseudopodial 
ons into its cavity (fig. 599) by whose agency (it may be 
tainly affirmed) the nutrient materiul is first introduced 
yody-substance. This process of ‘intracellular digestion’ 
oticed by Professor Allman in the beautiful hydroid polype 
3;1 the like has been since shown by Mr. Jeffery Parker 
of the ordinary Hydra ;? and Professor E. Ray Lankester 
the same observation upon the curious little Medusa (Limno- 
ately found in a fresh-water tank in this country, whither 
idoubtedly been introduced ; while the observations of 
have shown that a similar process obtains among the sea- 
3 (It may be mentioned in this connection, that Metschni- 
een the cells which line the alimentary canal of the lower 
‘worms gorging themselves with coloured food-particles, 
. the manner of Amebe and the liver-fluke, and that a 
£ larvee are known to obtain their nourishment in the same 
‘he second ‘survival’ of protozoic independence is shown 
straordinary power possessed by Hydra, Actinia, ke. of 
ag the entire organism from a mere fragment. This great 
icludes the two principal groups the Hyprozoa and the 
4, the former comprehending the Polypes, and the latter 
mes. In the Hydrozoa the mouth is placed on a projecting 
while in the Anthozoa it is sunk below the level of the oral 
tentacles, and the cavity developed from and connected 
ligestive cavity separates its wall from the body-wall and 
xd. by a series of vertical partitions or septa. As most of 
id polypes are essentially microscopic animals, they need 
cribed with some minuteness ; whilst in regard to the 
those points only will be dwelt on which are of special 
» the microscopist, 
zoa.—The type of this group is the Hydra or fresh-water 
very common inhabitant of pools and ditches, where it is 
nonly to be found attached to the leaves or stems of aquatic 
ating pieces of stick, &c. Two species arc common in t 
he 1. viridis or green polype, and the H. ru/yaris, which 
orange-brown, but sometimes yellowish or red (its colour 
le to some variation according to the nature of the food 
it has been subsisting) ; a third less common species, the 
is distinguished from both the preceding Ly the length of 
les, which in the former are scarcely as long as the body, 
the latter they are, when fully extended, inany times longer 





lia Britannica the‘ Challenger’ Reports by Professor Schulze, Menare, 
Mf, and Sollas; and the numerous memirs of Professors 
Dr. von Lendenfeld. 

It should be noted that Professor Claus called 












of Ray. 
«Journ. Micros. S vol. xx, 1880, p. 371. 
it an interesting article on Intercellular Digestion, by Metsclmikoff, in 
ntifique, ser. iii. vol. si. p. 688, 





3x2 





HYDRQZOA 789 


inference is founded upon the oft-repeated observation, 
living prey seized by the tentacles have a body destitute 
tegument, as is the with the minute aquatic worms 
stitute a large part of its aliment, this speedily dies, 
sh, instead of being swallowed, it escapes from their grasp ; 
the other hand, minute Entomostraca, insects, and other 
t ova, with hard envelopes, may escape without injury, even 
ng been detained for some time in the polype’s embracs. 
actility of the 
(the interior 
s traversed by 
tat communi- 
a the cavity 
mach) is very 
e, especially 
Tydra fusca, 
as, when ex- 
2 search of 
rot less than 
ght inches in 
hilst they are 
so contract- 
the stomach 
‘ith food, as 
mly like little 
round its en- 
3y means of 
raments the 
enabled to 
support from 
hose activity, 
red with its 
it powers of 
a, might have 
to re- 
m altogether 
reach ; for 
ts movements 
the water, a 
orm ora water- 
vens to touch Fro, 601.—Campanularia gelatinosa. 
1 tentacles of 
ve, spread out as these are in readiness for prey, it is 
ely seized hy this; other arms are soon coiled around it, 
unfortunate victim is speedily conveyed to the stomach, 
thich it may frequently be seen to continue moving for 
e time. Soon, however, its struggles cease, and its outline 
‘ed by a turbid film, which gradually thickens, so that at 
rm is wholly lost. The soft parts are soon completely dis- 
ad the harder indigestible portions are rejected through the 
A second oritice has been observed at the lower extremity 








fecundation occurs; a very strong elastic or capsule then 
forms round the ovurm, the surface of which is in some cases studded 
with spine-like points, in others tuberculated, the divisions between 
the tubercles being polvgonal The ovum finally drops from its 
icle, and attaches 11 by means of a mucous secretion, till the 
‘ing of the young Hydra, which comes forth provided with four 
imentary tentacles like buds, The Hydra possesses the of 
free locomotion, being able to remove from the spot to which it has 
attached itself to any other that may be more suitable to its wants ; 
its changes of place, however, seem rather to be performed under the 
influence of fight, towards which the Hydra sooks to move itself, than 
with reference to the search after food. 
The compound Hydroids may be likened to a Mydra whose 
instead of becoming detacl remain permanently connected 
with the parent ; and as these in their turn may dew 
from their own bodies, a structure of more or less ar’ 
character, termed a polypary, may be produced. ‘The form which 
this will mt, and the relation of the component polypes to each 
other, will depend upon the mode in which the gemmation takes 
; in all instances, however, the entire cluster is produced by 
continous growth from a single individual ; and the stomachs of the 
several polypes are united by tubes, which proceed from the base of 
each, along the stalk and branches, to communicate with the cavity 
ae cenical stem. aaa tiren a belies fate be by ree 
constituting tl lypary of a hydroir 4 wil 
found to be, or to contain, fleshy tubes having eee layers, 
the inner (endoderm) having nutritive functions ; the outer (ecto- 
derm) usually secreting a hard cortical layer, and thus giving rise 
‘ics of variousforms. Botwoen these a muscular coat is some- 
times noticed. The fleshy tube, whether single or compound, is called 
Aewnosere, and through it the nutrient matter circulates. The 
*zo0ids,’ or individual members of the colony, are of two kinds ; one 
the polypite, or alinentary zodid, resembling the Hydra in essential 
tA ‘ited bibs ee development of Baws es bs 
Jeinenberg, of whose admiral 
Pelth seltsbie reece elie oun, Gurr courn Micros Bet ae 
vol. xiv, J874, p. 1. See also the important paper by Mr. Jeffery Parker 
es pi eens Bc wear Me 
Team Mlorie Betas pease ne 


il 


I 


5 











DEVELOPMENT OF HYDROZOA 793 
img to the sub-order Athecata. At A is shown the ali- 
‘id, or polypite, with its tentacles, and at B the succes- 
a, b, ¢, of the sexual zodids, or medusa-buds. When 
developed the Medusa swims away, and as it grows to 
alarges its manubrium, so that it hangs below the bell. 
xe of the genus Syncoryne (as now restricted) have the 
. Sarsia in honour of the Swedish naturalist Sars. Their 
racter is that of free swimmers ; but Agassiz ascertained 
me cases towards the 
breeding season the 
ds remain fixed, and 
sir products while at- 
the zoéphyte.' This 
dition of the sexual 
ery common amongst 
da ; and various inter- 
ages may be traced in 
genera between the 
which the gonozodids 
ced in the common 
already described, and 
yneoryne. In Tubu- 
+ gonozodids, though 
tly attached, are fur- 
‘ith swimming bells, 
‘our tubercles repre- 
aarginal tentacles. A 
ind interesting species, 
t indivisa, receives its 
vame from the infre- 
ith which branches are 
‘rom the stems, these for 
part standing erect and 
ike the stalks of corn, 





base to which they are 

This beautiful zoé- 
hich sometimes grows 
the tide-marks, but is 
undantly obtained by 
in deep water, often 
» size which renders it 
s microscopic object, its 
ing sometimes no less 


Fro, 608—Development of Medusa buds 
in Syncoryne Sarsii: A, un ordinary 
polype, with its club-shaped body covered 








with tentacles; B, a polype putting forth 
medusoid gemma ; «, ‘ong bud ; 
b, a bud more advanced, the quad- 


rangular form of which, with the four 
nuclei whence the cirrhi afterwards 
spring, is shown at; c, a bud still 
more advanced, 





Several curious 


foot in height and a line in diameter. 
aa, however, are brought into view by microscopic examina- 
he polype-stomach is connected with the cavity of the 
acircular opening, which is surrounded by a sphincter ; 
alternate movement of dilatation and contraction takes 
it, fluid being apparently forced up from Lelow, and then 
again, after which the sphincter closes in preparation for 





1 Hincks, op. cit. p. 49. 





COLLECTING ZOUPHYTES + 795 


branches in their speek pertne bodies 

formerly supposed to be ova, but which are now known to be 
cae pipes ee sp meg 

are = te 

distinct pol; pena and ova; Sr ihe Lice 
lised by Fhe entrance of the former whilst still contained within 
their ‘The fertilised ova, whether produced in free or in 
seuual ach medusoids, develop themselves in the first instance into: 
cilinted a saens or planule, which soon evolve themselves into 
true pol; from every one of which a new composite polypary 


sare al el ar pare eh our coast which will not supply some or 


other of the pees and 
interesting forme ZO 
phytic life which have been 


Many of them Tavitealy 
live in that situation ; and 
others are frequently cast, 

up by the waves from the 





be made here of the gigantic 
oy igre igneetea E 
stem of which measui t 
seven feet four inches, re Gan eorloe eee ete 


of nine inches from tip to tip of the extended tentacles, and of the 
elegant Streptocantus imus, in which by the twisting of 
the stem the ultimate ramules are thrown into ‘a graceful and 
beautiful spiral.’ For observing them eh tele living state, no 
means is %o convenient as the zoophyte-trough. In mounting com> 

pound Hydrozoa, ns well as Belvo it will be found of a 
advantage to place the specimens alive in the cells th 

manently to occupy, and to then add osmic acid di py phe to 
the sea-water; this has the effect of causing the protrusion of the 

animals, and of rendering their tentacles rigid, The liquid may be 
withdrawn, and replaced uw Gondby’s solution, Deane’s gelatine, 
glyeerin-jelly, weak spirit, diluted glycerin, a mixture of spirit and 
glycerin with sea-water, or any other menstruum, by means of 











SELLY-FISHES 797 


d-eye’ group, of which Tawmantias (Gg. 605) may be 
representative, are really to be considered as the detached 
ius of the zodphytes from which they hare beea. 


veithwer side, and terminating tn the me rginal canal, ee. 


Wa —A, Thanmentins pitoreltc, one cf the ‘oshe2-ey 
tentactes ; 6, stomach; c, gustrovarcu'ar canals, hov 
ne Bachscholteii, Haeckel. 


| 
off, endowed with independent organs of nutrition and 
i swhereby they became capable of maintaining their own 
and of developing their sexual products. Th 
tion of these organs will be understocd from the accompanying 










REPRODUCTION OF ACALEPHS 799 


mplete above, and the upper discs usually presenting some 
sim diameter ; and whilst this is taking place the oages of 
8 become divided into lobes, each lobe soon presenting the 
th the supposed rudimentary eye at the bottom of it, which 
» plainly seen in the detached Meduse (fig. 607, C). Up to 
tiod, the tentacles of the original polype surmount the highest 
isca ; but before the detachment of the topmost disc, this 
rs, and a new one is developed at the summit of the 

ich remains at the base of the pile. At last the topmost 
gest disc begins to exhibit a sort of convulsive struggle ; it 





Fro, 606.—I, two Hydree tube (Scyphistoma-stage) of Cyanca 
capillata, with two (a, b) undergoing fission (Strobila-stage). 


II, a and’é of fig. I three days later. In a the tentacl 
developed beneath the lowest of the Ephyre, from the stalk 
of the Strobila, which will persist as 0 Hydra tube. (After 
Van Beneden.) 






re 


mes detached, and swims freely away ; and tho same series of 
ages takes place from above downwards, until the whole pile of 
is detached and converted into free-swimming Medusw. But 
original polypoid body still remains, and may return to its 
inal polype-like mode of gemmation, becoming the progenitor of 
w my, every member of which may in its turn bud off’ a pile 
[edusa discs. 

The bodies thus detached have all the essential characters of the 
\t Meduse. Exch consists of an umbrella-like dise divided at 
adge into a variable number of lobes, usually eight ; and of a 





4 ACTINOZOA 801 


eycle of phenomena is one of those to which the term ‘alter- 
jions’ was applied by Steenstrup,' who brought 
this designation » number of cases in which genera- 
not produce a form resembling itself, but a different form, 
tion B gives origin to a form which does not re- 
Dut returns to the form A, from which B itself sprang. 
ly pointed out, however, by the Author? that the term 
of ions’ does not appropriately represent the 
of this case or of any of the other cases grouped under 
eategory, the real fact being that the two organisms, A 
itute two stages in the life-history of one generation, 
{action of one form from the other being in only one 
@ traly generative or sexual act, whilst in the other it is 
‘of gemmation or budding. Thus the Meduse of both 
(the ‘ maked-cyed’ and the ‘ covered-eyed’ of Forbes) are de- 
A flower-buds, #0 to speak, of the hydroid zodphytes which bud 
off, the zouphytic phase of life being the most conspicuous in 
Yhecata as Campanulariida and Sertulariida, whose Medusa- 
re of small size and simple conformation, and not unfrequently 
pt detach themselves as independent organisms ; whilst the 
jaan phase of life is the most conspicuous in theordinary Acalephs, 
r tic stage being passed in such obscurity as only to be 
by careful research. The Author's views on this subject, 
were at first strongly contested by Professor E. Forbes, and 
yaminent zodlogista, have now come to be generally adopted.? 
—Of this group the common sea-anemones may be 
as types constituting, with their allies, the order Zoantharia, 
thoid polypes, which have numerous tentacles disposed in 
rows. Next to them come the dlcyonaria, consisting of 
pb whose polypes, having always eight broad short tentacles, 
at a star-like aspect when expanded ; as is the case with various 


eee ‘bodies, unpossessed of any hard skeleton, which 
















our own shores, and also with the red coral and the Tubipora 
seas, which have a stony skeleton that is internal in the 
and external in the second, as also with the sea-pens and 
ie or sea-fans, A third order, Rugosa, consists of fossil 
whose stony polyparies are intermediate in character between 
‘of the two preceding. And lastly, the Ctenophora, free-swim- 
gelatinous animals, many of which are beautiful objects for 
» are by some zodlogists ranked with the Actinozoa.* 
the Zoantharia the common Actinia or ‘sea-anemone’ may 
as the type, the individual polypites of all the composite 
ineluded in the group being constructed upon the same model.* 










‘hie treatise on The Alternation of Generations, a translation of which has 
the Ray Society. 
for. Med. Chir. Review, vol. i. 1848, p. 192 ef seq. 
Hauzley, Anatomy of Invertebrated Animals, p. 188; and Balfour, 
‘Embryol 


yi ps 151. 
lessor Hactkel, Yod 4 the study of Ctenaria ctenophora, associates the 
ra with the be re (Sitsungaber. Jenaische Gesellschaft, May 16, 1879). 
ae cho anatomy of Actinia and its allies, see O. and R. Hertwig’s monograph 
he: and xiv. of the Jenaische Zeitschrift. 3 
r 





802 SPONGES AND ZOOPHYTES 


partitions that divide the space in rOskaeen lee 


the general integument of the animal into separate chambers. This 
Seren gees v's seria Jans Se ene 
coral’ of tropical seus, which is the stony! a 

like animal ; on a far smaller scale, it Se sacra 
phyllia, a like solitary anemone of our own coasts, which is 
distinguishable from an Actinia by other character than the 
presence of this disc, and also on the toe 
corals known as ‘madrepores'; whilst in some of t the indivi. 
dual polype-cells are so small that the lamellated can 
only be made out when they are considerably Portions 
Sonar such ori cr ea ae are 
very beautiful objects powers, the former being vi 
redo, and the later by transmitted 
Ives pons of th cay -apcrapic aaa os pe 

lower powers ol oxy- mic use 
al socnbod ot pcoptita Notlons oR alana inbelie be G, 
von Koch ; the corals with all their soft par f 

in absolute alcohol, and then placed pak soluti copa ne 
form. After thorough permeation are taken 4 
slowly until the masses become quite hard, ‘These masses nay now 
he cut into sections with a fine saw and rubbed down on « whetstone 
in the ordi manner ; after staining, the sections may be mounted 
in Canada balsam, The great value of this method lies in the fact 


that by it the soft and hard parts are retained in their proper rela- 
tions othieast other! 


i 


The chief point of interest to the mi however, in the 
structure of these animals lies in the ext abundance and 
high development of those ‘ filiferous or ‘thread-cells,’ the 


presence of which on the tentacles of yard polypes has been 
already noticed, and which are also to be found, sometimes i 
sometimes very abundantly, in the tentacles sorrounding 
of the Medusw, as well ‘as on other parts of their bodies. If a 
tentacle of any of the sea~anemones so abundant on our coasts (the 
smaller and more transparent kinds being selected in : be 
cut off, and be subjected to gentle pressure between the two 
of the aquatic box or the compressorium, multitudes of little dart- 
like organs will be seen to project themselves from its surface near 
its tip ; and if the pressure be uallyangoesteg breif ee 
darts will every moment come into view. Not only do | ores 
present different forms in different species, but even in one and the 
same individual very strongly marked diversities are shown, of 
which a few examples are given in fig. 608 At A, B, , D is 
4 See Zoologizeher Anseiger, j. p. 30; and Proc. Zon, Soe. Loudon, 188, p. Mt 


I 


—_— || 


ALCYONARIA 803 


ppearance of the ‘ filiferous capsules,’ whils$ as yet the 
oiled up in their interior ; and at E, F, G, H are seen 
most striking forms which they exhibit when the thread 
tarted forth. These thread-cellsare found not merely in 
s and other parts of 


| imtegament of Ac- . n 
also in the long fila- 
a lie in coils within 
:3 that surround the 
1 contact with the 
is which are attached 


lse dividing the cham- 
latter sometimes con- 
-cells’ and sometimes 
ro sexes being here 
+ united in the same = * r . x 

‘What can be the 
1e filiferous filaments 
ned in the interior of 
> is difficult to guess 
re often found to pro- 
rents in the external 
vhen any violence has 
1 detaching the animal 
se ; and when there is 
rupture they are often 
vagh the wall of the 
to its cavity, and may 
ging out of the mouth. 
t of these capsules, in 
itected state, are about 
vinch in length ; while 
or dart, in Corynactis 
when fully extended, 
than 4th of an inch, 
ies times the length 





Aleyonaria a character- 

gle is found in the Alcy- 

ttatum of our coasts ; Fic. 608--Filiferous capsules of Acti- 
ynge-like mass, covered noz0a: A, B, Corynactis Allmanni; 
gh skin, which is com. $.¥.F: Caryophyltia Smithii; D 
en under the naiie of Astinta crassicornia; H, Actinia can- 
vs toes,’ or by the 

ant name of ‘mermaid’s fingers.’ When a specimen of 
t torn frum the rock to which it has attached itself, it 
into an unshapely mass, whose surface presents nothing 


.Goase's Naturalist's Rambles on the Devonshire Coast, and Professor 
ber den Bau u.s.w. der Nesselkapseln einiger Polypen und Quallen,’ in 
uturw. Verein ru Hamburg, Band v. 1866. On the relations of stinging 
nervous system, see Dr. v. Lendenfeld, Quart. Journ. Micros. Sci. n.s. 


Br2 








el 


SPONGES AND ZOUPHYTES 


Buen wor girs ‘orn tte thee Sn oe 
kappa again, and from ie 
Einiguerngetire resembles a exe 


7% 


beauty Wi raat recently taken, 
each of the potal-like tentacula is hey ctr 
Shad SHats cow co dctica’alyslasttae 
each margin, and pene | onwards ; an ita 
parities « hened eee with 

pesky ge After « : 

snp ao sor thik, TiGaaelyascieas! their 
ed; (Gosse.. When a ann of this: wort ts eue-dnby ik la found 
to be channelled out somewhat like a sponge by rami ; the 
vents of which open into the stomachal cavities of the: which 


are thus as eaaaiesiata fren communication with each | a cha- 
racter thn’ distinguishes this order, A movement of fluid 
is kept a within these canals (as may be distinctly seen through 





Fw. eee nes eh Aleponias Fra, Pp iparectprs ine ee guttates 


their transparent bodies) by meansof cilia lining the internal surfaces 
of the polyposis % far meas can be discerned on. gthened throngh- 
faces. The tissue o! spongy is steer pepe 
out, like that of sponges, with ere spicules (always, however, cal~ 
Packpte> which i remarkable for the ne “ oth See 
are disposed with great regularity arou: bases of the 
and even extend part of their length upwards on their In 
the Gorgonic or sea-fan, whilst the central part of the: 
consolidated into a horny axis, the soft flesh which this axis 
is so full of tuberculated spicules, eae in its outer | ontan lara 
when this dries up, they form a thick yellowish or reddish incrasta- 
tion upon the horny stem. This erust “fe however, so friable that it 
or rage easily rubbed down between the tingers, and he 
the microscope it is found to consist st of spicules of diersat 
shapes and sizes, more or less resembling those shown in figs, 609, 610, 


sometimes colourless, but sometimes of a beautiful crim: 


CTENOPHORA ‘ 805 


‘These spicules are-best seen by black-ground illumination, 
hen viewed by the binocular microscope. They are, of 
‘be separated from the animal substance in the same 
the calcareous spicules of sponges; and they should be 
Vike them, in Canada balsam. The spicules always 
organic basis, as is proved by the fact that when their 
wived by dilute acid a gelatinous-looking residuum is left, 
erves the form of the spicule. 
or ‘comb-bearers,’ are so named from the comb- 
sement of the rows of tiny ‘ paddles’ by the movement of 
bodies of these animals are propelled. A very beautiful 
‘common Foprosenvatire of this order is furnished by the 
idews-(fig. 611), very commonly known as the Bero#, which 
2, however, properly appertains to another animal (fig. 612) 
e grade of organisation. The body of Cydippe is a nearly 





‘1a. 611.—Cydippe pileus, with Fra, 612,—Beroé Forskalit, 
ite tentacles ext nded. showing the tubular pro- 
longations of the stomach. 


sass of soft jelly, usually about #ths of an inch in diameter ; 
y be observed, even with the naked eye, to be marked by 
ht bands, which proceed from pole to pole like meridian 
wo bands are seen with the microscope to be formed of rows 
xd filaments, far larger than ordinary cilia, but lashing the 
dhe same manner ; they sometimes act quite independently 
sther, 80 as to give to the body every variety of motion, but 
s work altogether. If the sun-light should fall upon them 
y are in activity, they display very beautiful iridescent 
In addition to these ‘paddles’ the Cydippe is furnished 
ir of long tendril-like filaments, arising from the bottom of 
cavities in the posterior part of the body, and furnished with 
anches (A) ; within these cavities they may lie doubled up, 
to be visible externally ; and when they are ejected, which 
18 quite suddenly, the main filaments first come forth, and 
tendrils sulsequently uncoil themselves, to be drawn in 





quantities at once by the stick-net, renders it a 
most beautiful sul for observation when due scope is, to its 
movements ; but for the sake of pi Reali rade) Sh 
course necessary to confine these, Various species of true Bero?,? 
some of them even attaining the size of « small lemon, are occasionally 
$a) eae ree ae cca ot all ne bedi pag | 
body are effected by the like paddles ‘meridional 
bands. These AS ieduinniene in een ‘the lumi- 
nosity is retained even by fragments of their bodies, being 
by agitation of the water containing them. All the C ore Ee 
from eggs, and are already quite advanced in deve- 


reproduced 
i it by the tim hatched. before 
IaecdSay wran out oie gene sctcy eitdn tas walle af ae 


diminuti is thei of locomotive at 
pir aay a ale eas 


Those who may desire to soquire a more 
euisia, Baba rtbeee pees lick eed ey see 

rw, in ndition ited, wa 
treatineron zoilogy Dr. Jehnston's History of British Zeephytes; Professoe Milne 





ie ws Polypen! “Histoire dee Corallaires 
Bites Bea) Eee Lear rte ee a eaten Polo oeds ease 
apa {in AMém. de Pca. Roy, 


de Bruxelics, tom. xvii wind hie!) 
Polypes qui Tes Cites 


ymentent de 
. G, Dalyell’s Kare and Remarkable Animate wh Le 
Mém. pour servir A Vhistoire d'un genre de Polype Team deuce; M 








' Tt is commonly stated that the two branches of the alimentary camal open om 
the wurtace by two re tated in the lw a the one eter nde the 
nervous ganglion, uthor, however, has not been hisnwolt 
‘ezlotence of such excretory. perso in Use eid Crip ox sg hes 
Tepeatediy injected their whole alimentary canal and and 
tively watched the enrrents produced by ciliary action im the interior of the hifaraat~ 
ing prolongations, which currents ah appear to him to retam ax from omeal 
extremities, He is himself inclined to bellere that this arrangement has 
solely tothe nutrition of the nervous ganglion and tentacular which 
imbedded (so to speak) in the on of the alimentary mows to be 
to draw ite supply of nutsiment direst from that nity, : 

* On tha anatomy of Herot, see Eimer, Zoolagivehe Stuitien auf Capri. I. Ceher 


Berot ovatus, Leipsig, 1873. 
5 Bee Korotnel, Leitechr. f Wiss, Zool. xitii, p. 2a 








— | 


CQELENTERATA 807 


‘gnparaphie du Genre + Aafia Ann. des a ci ser, i, tom, av. 
-¢ Organs of Campanularia genteu- 

rt Journ i Teor Sci. vol. iff. 1855, p. 59; Brotesice F: bala Laas 

 Leipaig, 1 per sae on mmcoryne, 187! fensor Agassiz’ 

mograph on American M ing the third it Profs his Contri- 
the Natural History rn the United States of America; Mr. Hincks! 
Zodphytes; Professor Allman's sdmirable memoirs on Cordylophore, 
hela in hie Trans. for 1858 and 1875; Professor ‘Tacaze-Duthiers’ 
the Development of Corals in 
Professor J. R. Greene's 









Bee also Prot 
: his Ilustrated Catalogue 
seus of Comparative Zoilogy at Harvard College; Professor James 
snevican Journal of Seionce, we. vol. xxxv. p. 848; Dr. D. Macdonald in 
¥,, Soe, Edinb, vol ail p. 016; Mr. HL N. Moseley, + On ie Ble Structure of 
a "in Phil. Trane. 1877, p. 117, and ‘ 
SB 45; ‘and on:tbe A. 








later treatises Professor y Lankorir's article 6 on m Byes i the oth 
lia Britannica; the ‘Chall of Professor 
(Plumulariids uly), Professor Haeckel on the Meduse, 
apeiny ae. Denn see Cinals, Ue. 8. lertwig on fie Sete Fee 
‘on the Alcyonaria, and Mr. George Brook on’ ipatharia; 
Gees ty De A nde op Aan acd by ‘Dr. C. Chun on C 
"'auna und Flora des Golfes von Neapel, should be consult 








STRUCTURE OF ECHINOIDS 


lar to their plane, are so arranged that the perforations in one 
eolisnaaag glare niet pees ere papt Toe 5 and 
‘transparence is such that when we are examining a section 
enough kg BAe two or raging iecperene by 
focussi he mi to ither one m into 
ee view, as his rosy Wingo but ay, beautiful a 
ment, it comes to pass that the plates of which the entire ‘test ‘is 


made wy a considemble degree of bratape iy notwith- 
maadan tosis orc okuatel iL Rher APs fection a fractured 


been removed, be laid upon fuid of almost any description, this will 
be rapidly sucked up into its substance. A very beautiful example 
‘of the same kind of calcareous skeleton, having 8 more regular con- 
formation, is furnished by the dise or ‘rosette’ which is contained 
in the tip of every one of the tubular suckers put forth by the living 
Echinus from the ‘nmbulacral pores” that are seen in the rows of 


ELE § 





Fo, 6i—Seotion of shell of Kehinus Fro, 614.—Tran:verse section of cen- 
sowing. the calcareous network of tral portion af spine of Heterocen- 
which it is composed: aa, portions frotus, showing its more open net- 
of w deeper layer, work, 


smaller plates interposed between the larger spine-beaxing plates of 
ite box-tike shell, If the entire disc be ent off and be Sinead 
when dry in Canada balsam, the calcareous rosette may be seen 
sufficiently well; but its beautiful structure is better made out when 
the animal membrane that incloses it has been got rid of by boiling 
in a solution of caustic potass ; and the appearance of one of the 
as ie of which it is composed, when thus prepared, is shown 

most beautiful display of this reticulated structure, however, 
is shown in the conformation of the ‘spines’ of Kehinus, Cidaris, &e. 
in which it is combined with solid ribs or pillars, disposed in such a 
manner as to increase the strength of these organs, a or and 
elaborate pattern being formed by their intermixture, which shows 
considerable variety in different species. When we make a thin 
transverse section of almost any spine belonging to the genus 
Echinus (the small spines of our British species, however, being 
exceptional in this respect) or its immediate allies, we see it to be 


i 


810 ECHINODERMATA 
ree SIE ae arrange aie ee 
strongly reminds us of the rings of inches boannen Ares 





F10, 615.—Tranayerse seotion of spine of Behimometra, 


(fig, 615). The number of these layers is extremely 
pending not merely upon the age of the spine, but xt ee 


its io em w os 





Fi. 016.—One of the segments of the ealeartous 
skeleton of: ant atubalacral diac of MeAinuas tion to be the sections of 


run in the direction of the length of the spine, and form the exterior 
of every layer. Their solidity becomes very obvious when we 


SPINES OF ECHINOQIDS Sur 


either examine a section of a spine whose substance is pervaded (as 
often happens) with a colouring matter of some depth, or when we 
look ata very thin section by black-ground illumination. Around 
the innermost circle of these solid rs there is another layer of 
Prearees Sex eid which again is qatenaae | Preset circle 
id pil 5 is ent may be repeated many times, 

as seus in fig. 617, ibe cn terscoek row of pillars forming the 
projecting ribs that are commonly to be disti on the surface 
of the spine. Around the cup-shaped base of the spine is a membrane 
which is continuous with that covering the surface of the shell, and 
serves not merely to hold down the cup upon the tubercle over whieh 
it works, but also by its contractility to move the spine in any required 
direction. The increase in size of the spine appears to be due to the 
substance which fills up the spaces in the open network 

of the spii ssrand jean cea Braco Habis new Feemiation 
completely vent dl ; not me! surrounding t - 
viously formed, but also projecting iderably beyond it ee das 
it happens that the number of layers shown in a transverse section. 





Fro, 617.—Portion of transverse seotion of spine of Heterocentrotus 
masnnitlatins. 


will depend in part upon the place of that section. For if it cross 
near the base, it will traverse every one of the successive layers from 
the very commencement ; whilst if it cross near the apex, it will 
traverse only the single layer of the last growth, notwithstanding 
that, in the elub-shaped spines, this terminal portion may be of con- 
siderably larger diameter than the basal ; and in any intermediate 
eee the spine, so many layers will be traversed as have been 

since the spine first attained that length. ‘The basal portion 
of the spine is enveloped in a reticulation of a very close texture, 
without concentri¢ layers, forming the cup or socket which works 
over the tubercle of the shell. 

Their combination of clegance of pattern with richness of colour- 
ing renders well-prepared specimens of these spines among the most 
beautiful objects that the microscopist can anywhere meet with. 
The Inrge spines of the various species of the genus Heterocentrotus 
furnish sections most remarkable for size and elabornteness, as well 
as for sfepth of colour (in which last point, however, the deep purple 
spines of Eehinws lividus are pre-eminent); but for exquisite 








Fig. 618.—Transverse section of a pian of Gonioridaris Rorigera, 


hich wh thet the prickles on ‘spine are formed. not by 
Erunt only, but alia by the innee toticular dase, (Prom Ball) 


tiesue, over which the subsequent layers have been formed as uaual. 
And sometimes a peculiar ring may be seen upon the surface of 
spine, which indicates the place of a complete all beyond: 
it being a new growth, whose unconformableness to 

basal portion is clearly shown by a longitudinal section.! The spines 
of Cidaris present a marked departure from the plan of steuetare 
exhibited in Echinus ; for not only are destitute of concentric 
layers, but the calcareous network which forms their 
substance is incased in a solid calearcous sheath perforated 
tubules, which seems to take the place of the separate pillars of the 
Echini, This is usually found to close in the spine at ite tip also ; 


* See the Anthor's description of such reparutions in the MoutMy Mveronepieal 
Journal, vol. UL 1870, p. 295, 


- 











SPINES; PEDICELLARLE 813 


Qs it would appear that the entire spine must be formed at 
mo addition could be made either to its length or to its. 
gave on the outside of the sheath, where it is never to be 
sheath itself often rises up in prominent points or 
the surface of these spines ; but, as is shown in fig. 618, 
‘portion may have a share in the formation of the rings. 
of the mode of formation of the Cidarid spine is con- 
‘Professor Jetfrey Bell, who has brought forward ' evidence 
that if two spines of different sizes be taken from two 
of Cidaris metularia, also differing in size, the quantity of 
: sheath seen in transverse section is proportionately 
‘the than in the smaller spine ; from this he concludes. 
is due to the internal reticulated portion rather 
outer crust. The slender, almost filamentary spines. 













Fio. 619.—Spine of Spatangus. 


8 (fig. 619) and the innumerable minute hair-like pro- 
Lath de to the shell of Clypeaster are composed of the Tike 
larly reticulated substance ? ; and these are very beautiful objects 
‘the lower powers of the microscope, when laid upon a black 
ind and examined by reflected light without any further prepara- 
4 It is interesting also to find that the same structure presents 
in the curious Pedicellaric (forceps-like bodies often mounted on 
stalks), which are found on the surface of many Echinida and 
and the nature of which was formerly a source of much 
y to naturalists, some having maintained that they were 
whilst others considered them as proper appendages of the 
itself. The complete conformity which exists between the 
of their skeleton and that of the animal to which they are 
removes all doubt of their being truly appendages to it, as 

ion of their actions in the living state would indicate.> 


Journ. Roy. Micros. Soc. 1884, p. 845. 

umber of rare spines are described and figured by Prof. H. W. Mackintosh 
da.xxvi. (p. 475) and xxviii. (pp. 241 and 259) of the Trans. Roy. Irish Academy. 
Prof. Alex. Agassiz has shown the relations of the Pedicellarim to the spines. 
information regarding the various forms of these curious bodies will be found 
lessor Perrier’s memoir in the Ann, Sc. Nat. (6), vols. xii. 3 Mr. Sladen’s 


> 











CALCAREOUS TISSUE Sr5 


convex surface of the tooth (c, ¢, ¢) is with a 
which has received the name of ‘enamel.’ This ix 


fo i ky ge tetag eee rire es ing base ; these consist 


particles,’ which are minute calcareous dises et Saas 
previously formed structures ; and it is he acon nensed 
ment of this connective substance that intervening spaces are 
narrowed into the semblance of tubuli like those of bone or dentine. 
‘Thus « vertical section of the tooth comes to present an ay 

very like that of the bone of a vertebrate animal, with its lacunw, 
canaliculi, and lamella ; but in a transverse section the body of the 
tooth bears a stronger resemblance to dentine ; whilst the keel and 
enamel layer more resemble an oblique section of Pinna than any 
other form of shell-structure. 

The caleareous plates which form the less compact skeletons of 
the Asteroidea (‘star-fish' and their allies) and of the Ophiuroiden 
(‘sand-stars * and ‘brittle stars’) have the same texture as those of 
the shell of Echinus, And this 
presents itself, too, in the spines or 

les of their surface when 
these (as in the great (oniaster 
or ‘knotty cushion-star } 
are large enough to be furni 
with a calcareous framework. An 
“aay pod of this kind, furnished by 
Te epee 
q . spines with whicl slate anid clear 
Gieaiot the species of Ophiothrix: wer ne 
(‘brittle star’) are beset are often 
remarkable for their beauty of conformation ; those of 0. penta- 
Salen, one of the most commion kinds, might serve (as Professor 
Forbes justly remarked), in point of lightness beauty, a8 


























(ergy rt 





t their Ai caears Tinton ak preserved.! 1] 
ihaccronlan stan 0 Encrinites the texture of the calcareous net- 
work is uniform, or nearly 60, throughout ; 





Ponti eran gate at tern ferme barton 
texture in different parts of the transverse section,’ 
Tosi sannbanebeectnrsice th li spiny soe ail pt 


of the skeleton of Echinodermata toes male thin 
sections made uy aoe, the general plan Me 
But their peculinr texture requires ‘dates certain one 


be taken ; in the first place, in ontario pease the section | 
beonay ait psogeniare to the di es enirable: Shick oes Rad 
the secon cosh the interapaces network from being: 
el by icles abraded in the an illus: 
eh ee Keel eut from « eplas of Mane oleae 
fig. 615. A section of the shell, spine, or other portion of the 
skeleton should first be cut with a fine a eal be rubbed on a flat 
file until it is about as thin as ordinary card, after: it 

be smoothed on one side by friction ith water on a Wi 


1 The éalcarsous skeleton evun of living Bchlnodenns han sorystallin 
sa very boa a the mone said rina Bekins or in 


thess scress, to avoid their to el 
calcite. And the Author is informed by Sf that the ealoareotis 
fills up the arcole of the fowsilived skeleton hae the same 
slceleton itself, aa is ahown not wany by the uniforesty: 7 
iat Rhett ilar atic cn pola : a 
Author's memoir ou ‘Stell Structure’ Report 
the British dasoclation, 18 


uh 


bk _sa—_ Lee 


PREPARING SPINES 817 


“It should then, after careful washing, be dried, first on white 
paper, afterwards by exposure for some time to a gentle 
“& no water-may be retained in the interstices of the net- 
‘would oppose the complete penetration of the Canada 
Next, it is tobe attached to a glass slip by balsam hardened 
(1 manner ; but particular care shoul be taken, first, that 
be brought to exactly the right degree of hardness, and 
there be enough not merely to attach the specimen to 
‘but also to saturate its substance throughout. The right 
of hardness is that at which the balsam can be with difficulty 
| bby the thumb-nail ; if it be made harder than this, it is 
y chip off the glass in grinding, so that the specimen also breaks 
5 andl if it be softer, it holds the abraded particles, so that 
senings of the network become clogged with them. If, when 
down nearly to the required thinness, the section appears to 
orm: and satisfactory throughions, the reduction may be com- 
hout displacing it ; but if (as often happens) some inequality 
ess should be observable, or some minute air-bubbles should 
themselves between the glass and the under surface, it is desir- 
Toosen the specimen by the application of just enough heat 
the balsam (special care being taken to avoid the production 
air-bubbles) and to turn it over so as to att the side 
hed to the glass, taking care to remove or to break with 
dle point any air-bubbles that there may be in the balsam 
ig the part of the glass on which it is laid. The surface now 
ght uppermost is then to be very carefully ground down, 
al care being taken to keep its thickness uniform through every 
iwhich may be even better judged of by the touch than by the 
d to carry the reducing process far enough, without carrying 
oo far. Until practice shell have enabled the operator to judge 
bby pussing his finger over the specimen, he must have con- 
recourse to the microscope during the latter stages of his 
k: and he should bear constantly in mind that, as the specimen 
become much more translucent when mounted in balsam and 
d with glass than it is when the ground surface is exposed, he 
‘not carry his reducing process so far as to produce at once the 
ire translicence he aims at, the attempt to accomplish which 
iii involve the risk of the destruction of the specimen. In 
ing’ the specimen liquid balsam should be employed, and 
very gentle heat (not sufficient to produce air-bubbles or to 
the specimen from the glass) thould. be applied ; and if, after 
‘been mounted, the section should be found too thick, it will 
to remove the glass cover and to reduce it further, care being 
io harden to the proper degree the balsam which has been 
fly Iaid on. 
Tia number of sections are to be prepared at once (which it is 
‘useful to do for the sake of economy of time, or in order to 
ire sections taken from different parts of the same spine), this 
ye most readily accomplished by laying them down, when cut 
J the saw, without any preliminary preparation save the blow- 
(eof the calcareous dust from their surfaces, upon a hin slip of 
@ 
















































surface leas be occupied by the sections > 
chief precaution required that all the een 
equally close ania with ethan surfaces may then be 


ential characters, This subject is one that has been: re babes 
little studied, Mr. Stewart being the only microscopist: 
much eed to it,! but it is well worthy of much more extended 
research. 

It now remains for us to notice the curious and often very beauti- 
ful structures, which represent, in the class Ji v 
calcareous skeleton of the classes already noticed. The 
number of the animals belov, to this order are ‘listingished by 
the flexibility and absence mness of their envelopes ; and ex- 
cepting in the case of the various species which have a set of a 
eous plates, disposed around the wall of the pharynx, we do not 
among them any representation, that is srpitee to the mnassisted: 
eye, of that skeleton which constitutes so distinctive a featureot the 


1 See his dt in the Linu Traneaes =r. i - 
Seurm: Ropeitiane Goa eke Te 


HOLOTHURIAN SPICULES 819 


werally.' Bat a microscopic examination of their integument 
+ beings to view the existence of great numbers of minute 
1 plates, every one of them presenting the characteristic re- 
id structure, which are sef with greater or less closeness in 





‘Fro. 688.—Holothuricides : I, Stichopus Keforsteinii ; a, calcareous 
plate of same; 5, c, calcareous plates of Holothuria vagabunda; 
, the same of H. inhabilis ;¢, the same of H. botellus; f, of H. 
pardalis; g, of H. edulis, 


betance of the skin. Various forms of the plates which thus 
themselves in Holothuria are shown in fig. 622. In the 
“a, one of the long-bodied forms of this order, which abounds 
1 Mediterranean Sea, and of which two species (the S. digitata 

inherrens) occasionally occur upon our own coasts, the cal- 
w plates of the integument have the regular form shown at A, 


ex 7 


Fro. 638.—Calcareous skeleton of Synapta: A, plate imbedded in 
the name, with its anchor-like apine attached ; C, anchor- 
like spine weparated. 








3 ; and each of these carries the curious anchor-like appendage 
ich is articulated to it by the notched piece at the foot, in the 
w shown (in side view) at B. The anchor-like appendages 


© an account of a very remarkable form nee Moseley ‘On the Pharynx of an 
n Holothurian, of the family Dendrochirote, in which the calcareous skeleton 
‘kably developed,’ Quart. Journ. Micros. Sci. n.s, xxiv. p. 255. 

n the spicules of Synapta, together with wome general remarks on the archi- 
of Echinoderm spicules,’ consult R. Semon, Mitth. Zool. Stat. Neapel, vii. 





Ba2 





= these sections, when d 
remem He see 
their transparence is greatly Leariabe All pag i aad 


ost. beautifull red the black- and 
their solid rretepipen te ty akon peat 


Be lid farsa ts aa ae ee is better seen. 
with the binocular than it can be with the microseope.?- 
Echinoderm Larve.-We have now to notice remark. 





able set of objects furnished to the mi ‘the dare 
states of this class ; for our knowl of which wo aro | chially i=. 
debted to the instaking and widely extended in 

Professor J. Miiller.* All that our limits pent ina notice ‘af two of 
the most curious forms of these larve by way of sample of the won~ 


‘ No systematic account of a species of Holothurian ean de resnelod ad conaghiab 
schich does not contain an account of the form ot its spicules; shew teas 
Fugues a varia wil be fond "age Wes 
lippinen thurion, le * Challenger’ 
Profestore Bell Loswig ad len 


sien. as 
? Itmay he here pointed ont that the 
cyte en be sont ng n any ane =e 
of faseagen channelled out in solid calc ‘ealoareou 
ditions, in whioh the relation between the sis neared and beet 
S* completaly reversed, there is every interme 
Of later works consult especial . 


08 
gol ii, Kobinodermata,” edited by Mx, A. iota eeu ix, of the ‘ 
fusenm of Comparation Zoilogy on 





LARVAL ECHINODERMS 821 


















nomena which his researches brought to light, and to which 
ntion of microscopists who have the opportunity of studying 
ould be the more assiduously directed, as even the most deli- 
‘these organisms have been found capable of such perfect 
tion as to admit of being studied, when mounted as pre- 
even better than when alive. The larval zodids have, by 
adaptations to their mode of life, acquired a type quite 
from that which characterises the adults ; for instead of a 
mmetry they exhibit a bilateral, the two sides being pre- 
e, and each having a ciliated fringe along the greater part 

e of its length. The 
ges are united by o 
and sn inferior trans- 


erorniann. Me their aie, 
parts ; ere is also 
iderable diversity in the 
orders as to the propor- 
if the fabric of the larva 
enters into the compo- 
of the adult form. When 
ang begins to acquire the 
rs of the fully developed 
th and sea-urchin, the 
which are not retained 
up, and their substance 
to feed the young form. Fia. 625,—Bipinnaria asterigera, or larva 
“One of the most remarkable eieontenge a sion a’, qenophagas; 1 b, 
Ne of Echinoderm larvee is jn which the mouth in situated; dd, bic 
& which has received the lobed peduncle; 1, 4, 3, 4, 5,6, 7, ciliated 
Re of Bipinnaria (fig. 625), sna. 
w the symmetrical arrange- 
kt of its natatory organs. The mouth («), which opens in the 
of a transverse furrow, leads through an esophagus, a’, to a 
stomach, around which the body of a star-fish is developing 
if ; and on one side of this mouth are observed the intestinal 
wand anus (5). On either side of the anterior portion of the 
are six or more narrow fin-like appendages, which are fringed 
cilia ; and the rior part of the body is prolonged into 
wort of licle, bilobed towards its extremity, which also is 
vered with cilia. The organisation of this larva scems completed, 
ita movements through the water become very active, before the 
am at its anterior extremity presents anything of the aspect of the 
arfish, in this respect corresponding with the movements of the 
of the Echinoidea. The temporary mouth of the larva does 
Ptremain as the permanent mouth of the star-fish ; for the oso- 





a a 


822 ECHINODERMATA 


and the true mouth is Bretford) Sens 
ceaitegennsntonabe cen surface. ‘The young 





The 

issues from the ovum as soon as it has attained, by repeated ‘seg- 
mentation’ of the yolk, the condition of the ‘mulberry mass,” aud 
the superticial cells of this are covered with cilia by whose agency 
it swims freely through the water. So rapid are the early processes 
of development that no more than from twelve to 

hours poate between, Sangin oe eee 
the division into two, ir, or even it be ae place 
within three hours after impregnation, Wi! a few hours 

its emersion the embryo changes from the spherical into a sub- 
preaiin form with a flattened base; and in the centre of this 


? 


is a depression, which jually deepens, so a8 to form a mouth 
that communicates with a bere in the interior of tha body Which, 
is surrounded by a portion of the yolk-mass that has ‘to the 


liquid ular state. Subsequently a short intestinal tabe ue 
ks ak gest Deal ane eile ob kane Tee onal 
is at first triangular, but it afterwards becomes quadrangalar ; and 
the angles are meals round the mouth ve base), whilst 
the apex of the py: is sometimes much in the opposite 
direction, but is sometimes rounded off into a kind (Bg. 
626, A). All parts of this curious body, and especially its most 
projecting portions, are strengthened by « framework of thread-like 
calcareous rods (*). In this condition the embryo swims | 
through the water, being propelled by the action of the cilia, 
clothe the four angles of the pyramid and its fahipieictidmse oo 
which are sometimes thickly set upon two or four Projecting 
(/) ; and it has received the designation of Plutews 
eemibepanee He ss sort of oa mt angles frtbecr 
prolonged into four ler processes (y, 7, 9, @) shorter 
outer legs, but furnisued with a similar calcareotal y 

‘The first indication of the production of the young Echinus from 
its ‘pluteus’ is given by the formation of a circular Free Gears! 
A, c) on one side of the central stomach (6); and this dise soon 
presents five prominent tubercles (B), which subsequently | 
elongated into tubular processes, which will form the * 


; 


i 


racking 
il 





TARVAL ECHINE 


fect’ of theadult. Thedise gradually 

and between its tubules the rudiments of 

0); these, with the tubules, increase 
ew 


pluteus closes up. By 
the time that disc 
a grown over half of 
gastric sphere, ve 
little of tbe plates 3 
mains, exeept some of 
the slender calcareous 


nicking. feet nd 
shell is last extended ; 9, and opines, 2, projecting considerubly from the 
and ‘he Gist indication Sortace. aa in Gyan Dy he Pittens nob 
of it consists in the ap- favein hosing relatively wuallas) 


pearance of the five cal- 

carcous concretions, which are the summits of the five jons of 
the framework of jaws and teeth that surround it. All traces of 
original pluteus are now lost; and the larva, which now 
presonts the general aspect of an Echinoid animal, gradually 
Augments in size, multiplies the number of its plates, cirrhi, and 


& 

























ANTEDON 825 


0 that, notwithstanding its locomotive power, it is nearly aa station- 
ary in hes adult condition as a lier 
Thompson; of | i ori 


ee 


\s begun to make their appearance, and the skeleton 
when u esmmined e fount to conan of the ollowing pi 
of the stem ; r', the circle of iret radials, now interposed between 
basals and the orals, and si venieee se both ; between two 
thee ie orcs ec eine anal plate « ; whilst: they support 
second and third radials (r*, +), from the latter of which 
bifurcating arma spring ; finally, between the second radials we 
the five orale lifted from the hasals on which they originally 
by the interposition of the first radials, In the more advanced 
shown in fig. 628, 3, we find the highest joint of the stem 
ing to enlarge, to form the centro-dorsal plate (2, ¢ d), from 
are beginning to spring the dorsal cirrhi (cir) that serve to 
anchor the animal when it drops from the stem ; this supports the 


BEERES 


Hi 





z 
ee 
& 


1 The pentacrinaid larvw of Antedon have been found abundantly (attached to 
seaweeds and zouphytes) at Miliport, on the Clyde, and in Lamilash Bay, Arran: in 
Kirkwall Bay, Orkney; in Lough Strangford, neay Belfast, and in the Bay of Cork; 
and #t Ifracombe and in Saleanbe Bay, Devon, 


| $26 ECHIY ODERMATA 








24.—Pentacrinoid larva of Antedon. 1. Skeleten of early pentaerinold, 
black-ground illumination, showing ite component plates: 6, 
culated bolow to the highest point ef the stem 
radials, between two of which ix seen the single anal plate, « 
radials; 9°, third radials, giving off the bifureating arms at their smssits 
6, 0, orals.' % 3. Back and front views of a more advanced pentecrinold 
an ween by incident light, ane of the pair of arms being cut away im fig.* 
in order to bring the mouth and its surrounding parte into view: Bb 
cond, and third radinix; a, anal, mew carried 
mof the vent, ©; 0,0, orala; ofr, dorsal cirthk 
t joint of the wtem. 














basal: ry rt, 
upwards by the ju 
dov eloped from the 





ANTEDON 827 


1 rest the first radials (r') ; whilst the anal plate is 

to the ‘level of the second radials (r?) by the 

anal fannel or vent to which it is attached. The 
not at first apparent, as they no longer occupy their 
mt on being carefully looked for they are found still 
t around mouth (3, 0, 0), not having undergone 
size, whilst the visceral disc and the calyx in which 
ve greatly extended. These orl plates finally dis- 
ption ; the basals are at first concealed by the 
mt of the centro-dorsal (which finally extends so far 
@ first radials also) ; at last undergo metamor- 
autifal ‘ rosette,’ which lies between the cavity of the 
wi that of the palyx, In common with other members 
Aistedon is in its earliest phase of develop- 


wioming ‘larval poll 08 pecidetnbrao: which was. 
y- Busch, and has been since carefully studied by 
file ' and Goette.? This zodid has an 

‘form, and is furnished with transverse bands of 
Wisouth and anus of its own. After a time, how- 
‘68 the calcareous plates forming the stem and calyx 
hemeelves in its interior ; a disc is then formed at the 
rity by which it attaches iteelf was sea-weed (very 
‘maria), zobphyte, or polyzoary ; the calyx containing 
bh, sing its senboady mouth surrounded by tentacles, is 
od ; and the sarcodic substance of the pseudembryo, 
salyx and the rodimentary stem were originally in- 
ly shrinks, until the young pentacrinoid presents 
tacteristic form and proportions.* 


lopment of Antedon rosaceus’ in Phil. Trans. for 1865, p. 518. 
rosk. Anat. Ba. xii. p. 588. 

‘eralie of the Author's own later studies of this most interesting 

[iigkier of the entire geological succession of Crinoidea) are 

communicated to the Proceedings of the Royal Society tor 

yuent note, p. 451. Of the further contributions recently 

hie of it the memoir of Dr. H Ludwig ‘Zur Anatomie der 


forming of hin Morphologische Studien an Echino- 
Bagertnt "Thee who wish to carry further their study of the 
rte, 






‘two monographs by Dr. P, Herbert Carpenter in the 








parti 
tions matter anced rifle tentin; m, ovary; 
4oe pharynx, 2, the. pactvisoeral carla py one 
care by « reno cavity? tarfurer i, 1, muscles. Dy yar 
valve at ¢; and this tion of the lophophore more enlarged: a a, tenta- 
cula; 6 & their internal canals; ¢, their muscles ;, 
opens into — %, jophophure; ¢, ita retractor muscles. 


occupies a considerable part of the visceral cavity. (In the Bovwer- 


1 ‘Phin communication between the tentacular and visceral cavities ia denied by 
Dr. Vigelivs, who has recently made a earefal search for it, 








| 


$30 * POLYZOA AND TUNICATA 






i at its 
mat 4 aston of ‘dese 
eanete eae is (es it gill doubled 


Fe een 






630,—Colls of Polyzoa : A, Mastigophora Hy i ey 
ios B ‘Oribvilina. figularies . Graben ally flowing over them. 


verrucosi. The production of 


genie or buds 
take place either from the bodies of the polypides themselves, 
is what always happens when the cells are in mutual ition, 


or front ie connecting lens oF “stolen were 
one from the other, as in Laguncwla. In the latter case , 
first seen a bud-like protuberance of the horny external 
ment, into which the soft membranous lining s itself 
cavity thus formed, however, is not to become (as in 7 ts 
allies) the stomach of the new zodid, but it constitutes the chamber 
surrounding the digestive viscera, which organs have their 

in a thickening of the lining ne 

of the cavity into its interior, and gradi shapes itself into. 
alimentary canal with its tentacular appent se OF the | 
tion of gemmue from the polypides themselves the best ex: 
furnished by the Flustre and their allies. From a single cell o 
Flustra tive such buds may be sent off, which 










POLYZOA x 831 


sail erat rupture, and set free th 

wall ; wl se © spermatozor, 
Ce eeuie evra tal inithe iaiidie? thaigtweral svi . The ova, 
on the other hand, are formed in an ovarium, , which lodged in 


with, 
tinall; by an outlet at p, beneath the tentacular circle. 

creatures possess a considerable number of muscles, by 
hich their bodies may be projected from their sheaths, or drawn 
within them ; of these muscles, r, # ¢, 1 v, 1, the direction and 
points of attachment, sufficiently indicate the uses ; they are for the 
most part refractore, serving to draw in and double up the body, to 
fold together the circle of tentacula, and to close the aperture of the 
sheath, when the animal has been completely withdrawn into its 
interior. Bee sraetien sash ea at cage usa a the con- 
trary, appear to be chiefly accomplished by a general pressure upon 
the Seaniks which will tend to force out all that can be expelled from 
it. The tentacles themselves are furnished with distinct muscular 
fibres, by which their separate movements seem to be ) At 
the base of the tentacular circle, just above the anal oritice, is a smali 
body (seen at A, @),which is a nervous ganglion ; as yet no branches 
have been distinctly seen to be connected with it in ies ; but 
its character is less doubtful in some other Polyzoa, ides the 
i it movements of the individual polypides, other movements 
Rese be cba ted which are Laie by so many of them Lege 

as to indi ¢ existence of some connecti: ; an 
ta Se nee 
tem. 


4 


connecting agency, it is affirmed by Dr. Fri iller,? is fur- 
nished by what he terms a ‘colonial nervous» In a Seria- 
Jaria having « branching polyzoary that spreads itself on sea-weeds 
over a space of three or four inches, he states that a nervous 
m imay be distinguished at the origin of each branch, and 
ganglion at the origin of each polypide-bud, all these 
ganglia being connected together, not merely by principal trunks, 
but also by plexuses of nerve-tibres, which may be distinctly made 
* For farther details consult Haddon ‘On Budding in Polyzoa, Quart. Journ. 
Micros, Sei, xxiii. p. 616. 
? Seo lik memoir in Wiegmann's Archiv, 1860, p.011, translated In Quart. Journ. 
‘Micros, Sei. nx. vol. i. 1861, p. 900; Rev, T. Hincks’ * Note on the Movements of 


Vibracala its Caberre Lory, ra common Neryous System in 
the Polyzoa,’ Quart, Journ, Te 








GROUPS OF POLYZOA 833 


















it of “the remarkable distinctness with which the various 
their organisation may -be seen and the very beautiful man- 
ich their ciliated tentacula are arranged upon a deeply 
or horse-shoe-shaped lophophore. By this peculiarity the 
Polyzoa are distinguished from’ the marine ; and they, 
we marine Rhabdoplewra, may be further distinguished by the 
of an epi or movable process above the mouth, 
Allman calls them the Phyluctolemata, as com- 
the others which ate (ymnolemata, or have no epistome. 
y0f the Phylactolemata are for the most part lodged in a 
i sub-stratum which spreads over the leaves of 
plants, sometimes feeming masses of considerable size ; but 
-@urious and ‘beautiful Cristatella the polyzvary is un- 

#0 as to be capable of moving freely through the water.! 
marine Pol: constituting by far the most numerous 
‘of the class, the anus either opens outside (Ectoprocta) or 
) the circlet of tentacles ; the former comprise 
:—I. Cheilostomata, in which the mouth of the cell is 
|, or not quite at its extremity (fig. 630), is somewhat 
in forn, and is furnished with a movable (generally mem- 
lip, which closes it when the animal retreats. This includes 
part of the species that most abound on our own coast, not- 
g their wide differences in form and habit. Thus the 
of some (as Flustra) are horny and flexible, whilst those 
(as Eschara and Retepora) are so penetrated with calcareous 
fas to be quite rigid ; some grow as independent plant-like 
(as Bugula and Gemellaria), whilst others, having a like 
t, form, creep over the surfaces of rocks or stones (as 
) ; and others, again, have their cells in close apposition, 
crusts which possess no dletinite tigure (as is the case with 
and Membranipora). TI. The second order, Cyclostomata, 
of those Pulyzoa which have the mouth at the termination of 
caleareous cells, without any movable appendage or lip (fig. 
hk This includes a comparatively small number of genera, of which 
Kis and Tubulipora contain the largest proportion of the species 
Focour on our own coasts. III. The distinguishing character of 
Whird order, (tenostomata, is derived from the presence of a comb- 
beircular fringe of bristles, connected by a delicate membrane, 
lind the mouth of the cell, when the animal is projected from it, 
fringe being drawn in when the animal is retracted. The poly- 
of this group are very various in character, the cells being 
horny and separate (as in Farrell« and Bowerbankia), 
fleshy and coalescent (as in Alcyonidium). IV. In the 
which are represented by Loxosome and Jrdicellina, 
fare doubtless the most archaic of the true Polyzoa, the lopho- 
is produced upwards on the back of the tentacles, uniting 
tm at their base ina sort of muscular calyx, and giving to the 
imal when expanded somewhat the form of an inverted bell, like 
{2 See Professor Allman’s beautiful Monograph of the British Freshwater Polyzoa, 
4 by the Ray Society, 1467; and J. Jullien, ‘Monogianhie dex Bryozouires 
douce,’ Bull, Soc. Zool. de France, x. p. 91. 


3a 





-— 


Echini, i 
soctenthes tree latter would seem to be the func- 
tion of the wi which are long bristle-shaped organs (fig. 630, 

A), each adc nh Beolipelhah Rf eup that econ! 

museles by which it is kept in almost constant motion, sweeping 
slowly and carefully over the surface of the polyzoary, and removing 
what might be injurious to the delicate ii itants of the cells when 
their tentacles are ded. Out of 191 species of Cheilostomatous 
Polyzoa deseribed Mr. Busk, no fewer than 126 are furnished 
either with avicularia, or with vibracula, or with both these prpenet 
Tanicata.—The vovlogical position of the Tunicata, which has 
long been a subject of great discussion, appears to be now approxi- 
settled ; the study of their ceeeopensth has shown that 
they are provided with a notochord, and that their nervous system 
follows course which is characteristic of what are often called 
Vertebrata, but should better be called Chordate, As the noto- 
chord is always restricted to the hinder part of the body, the 
Tunicata may be called Urochordata. In all (except, Ps 
ieularia) there are distinct signs of degeneration. have 
been named Tunicata from the inclosure of their bodies in a ‘ tunic,’ 
which is sometimes leathery or even cartilaginous in its texture, and 
which sometimes includes caleareous spicules, whose forms are often 
Beyonce! They are often found to resemble the Polyzoa in 
tendency to produce composite structures by gemmation ; but in 
their habits they are for the most part very inactive, exhibiting 
‘scarcely Steed comparable to those rapid movements of expansion 
and retraction which it is so interesting to watch among the Polyzoa ; 
whilst, with the exception of the Salpide and other floating species 
which are chiefly found in seas warmer than those that surround our 
coast, and the curious Appendicularia to be presently noticed, they 
are rooted to one spot during all but the earliest period of their lives, 
‘The larger forms ny the Ascidian group, which constitutes the bulk 
of the class, are always solitary ; not propagating by gemmation, 


‘\ See Mr. G. Busk’s ‘Remarks on the Structure and Function of the Avicularian 
Vibracular x of Polyzoa' in Trans. Micros, Soc. ser, ii. vol. ii, 1864, 
p20; and Mr. A.W. Waters, “On the use of Avicularian Mandible in the deter- 
1. Roy. Micros. Soc, (2), ¥. ph. 174. 
Suz 









TUNICATA 837 


























and the anatomy of a single individual are displayed in 
Its clusters appear almost completely inanimate, exhibiting 
obvious movements when 
3 but if they be placed 
in sea-water a slight 
‘of the orifices will soon be 
and a constant and 
series of currents will be 
enter by-one set and to be 
‘by the other, indicating that - 
machinery of active life is 
-en within these apathetic 
In the family Polyclinide 
this genus belongs the 
is elongated, and may be 
Minto three regions : the thorax 
ich is chiefly occupied by the 
sac; the abdomen (B), 
contains the digestive appa- 
}; and the post-abdomen (0), in 
the heart and generative 
are lodged. -At the summit 
thorax is seen the oral oritice, 
: leads to the branchial sac ¢ ; 
forated by an immense 
of slits, which allow part of 
Fwater. to pass into the: space 
the branchial sac and the 
mantle. At ‘is seen the 






SS 





Fro. 682.—Compound mass of Amaroucium proliferum with the anaton 
single zovid: A, thorax; B, abdomen ; C, post-ubdomen ; ¢, oral orifice ; 
¢, branchial xac; f, thoracic blond-vesel : i, atriopore ; i’, projection over: 
Dauging it; j, nervous ganglion; k, aophaguy; /, stomach surrounded by 
digestive tubuli ; 2, intestine ; 2, anux opening into the cloaca formed by 
the mantle ; 0, heart; o', pericardium ; p, ovarium ; p’', exy ready to escape; 
q, tentis; 7, spermatic canal; 7’, termination of thix canal in the cloaca. 














yphagus, which is continuous with the lower part of the pha- 
I cavity ; this leads to the stomach, /, which is surrounded 
dular follicles; and from this passes off the intestine, m, which 
minates at n in the vent. A current of water is continually 





beautiful stellate gelatinous incrustations r 
sea-weeds and submerged rocks (fig. 633). The anatomy of 
animals is very similar to that of the Amaroucium already d d 
with this exception, that the body exhibits no dis it o i 
all the organs being brought together in one, which must 
sidered as thoracic, In this respect there isan evident: a 
towards the solitary species,' 

‘This approximation is still closer, however, in tho * 
dians, or Clavellinide, in which the general plan o 
nearly the same, but the zodids are simply connected by: 
instead of being included in a common investment ; 50. 
relation to each other is very nearly the same as that of 


1 For more special information see the | 
ally the admiral sseaserartist Padenac tie vison 
mont, “On the Structure and Functions of Tubular wid Col 
Ascidiw,"in the Phil, Trana, U4; nnd the artiole © Taniewta,” 
Jonvs, in the Cyclopedia of Anatomy and Physiology, 









TUNICATA : 839 


Hage e soats ice of jelly, dotted with orange and brown, and 
ee hen silvery winding thread. The isolation of the body of 

each zodid from that of its i fellows, and the extreme dn the bol of 
its tunics, not only enable the movements of fluid within the body to 





rifice escapes 


Fro, 6aa—Botrylie violaceus: A. claster on the surface of Fucus; 
B, portion of the same enlarged. 


into the space between the sac and the mantle, and is thus dis- 
charged immediately by the atrial funnel. Whatever little particles, 
animate or inanimate, the current of water brings flow into the 
sac unless stopped at its entrance by the tentacles, which do not 
appear fastidious. The particles which are admitted usually lodge 
somewhere on the sides of the sac, and then travel horizontally until 
they arrive at that part of it down which the current proceeds to the 
entrance of the stomach, which is situated at the bottom of :the 
snc, Minute animals are often swallowed alive, and have been 
observed darting about in the cavity for some days, without any ap- 
parent injury either to themselves or to the creature which incloses 
them. In general, oe eee which are unsuited for reception 
into the stomach are rejected by the sudden contraction of the mantle 
(or muscular tunic), the atriopore being at the same time closed, so 
that they are forced out by a powerful current. through the oral 
orifice. The curious alternation of the circulation that is character- 
istic of the class generally may be particularly well studied in 
Perophora. The creeping stalk that connects the individuals of 











840 POLYZOA AND TUNICATA 


cede peer ys 

trunk ; this trunk subdivides into vessels (or 

mere SA ok ee Rone ona raven 
ramify over iratory sac, A at 

between srg oval fal lite, “i others are first, 

stomach and intestine, and to the roll eciloge 8 taiaal ate mead 


TOT 
TEED 
ATLOLNT 
























still 

othe the 

Fin. 634- Serger longitadinal section of Perea F of much. ratios 

ihw branchial sec the alinentary ennai tO the micrascopist, which 

from the Jat bri Reseihin eid alone can be noticed here. 

atari, atrial si test; hy mnt After the ordinary repeated 

ag Mg agen tation of Uh yolk, 

fii, tentacles gl, noural gland aay amo: whereby « ‘anulberry: 

phageal apertury; st a a sort of ri 


a 
E 
i 


stomaah de. eum. ves jue the mantles tail-like t r 
Arava Towel od uncial eeu OF the gall wheal 
\e Tongitudinal vessel of y ¥ 

ay stigmata of branchial mec; ee, and more detached from 
bre, brinchioenrling it, save at the part from 











vessel | aplir 
(After Herdman,) 


the cloaca, or soon after it has escaped from the vent, its: p 





establ through the 

alimentary canal, The embryonic development of other Ascidians, 
SE tale al baat Pacem eee rene 9 is the 
same as the foregoing, a free tadpole-like larva always produced 
Plea rerie instance with the curious exception of some species of 
la. « 
This larval condition is represented in w very curious adult free 
Smaing term, termed Appendicularia, which is uently to be 
taken with the tow-net on our own coasts. This animal has an oval 
or flask-like body, which in large specimens attains the length of 
one-tifth of an inch, but which is often not more than one-fourth or 
one-fifth of that size. It is furnished with a tail-like appen 
three or four times its own length, broad, flattened, and rounded at 
its extremity ; and by the powerful vibrations of this it 
ee prveelied rapidly through the water. The structure of the body 

itfers greatly from that of the Ascidians, its plan being much simpler ; 
in particular, the pharyngeal sac is entirely destitute of ciliated 
branchial fissures opening into « surrounding cavity ; but two canals, 


‘The study of the development of Arcidians derived @ new interwat und im- 
from the discovery, made ly Kowalevaly iu 1807, tha thelr free-ew 


[abs leer rapier Meepeie Arpealien Ar coy ap ene ripe eter 
Gnnings of « wpinal marrow and a wotochord; thus bridging over the golf thatwus 
te them from Invertebrata, and (when n in connection with 


= 











poned to ey 

‘the curious: ‘Asean affinities of Amphionns, the lowest vertebrate at present known) 

afording strong for belief in the dorivation of the vertebrate and tunicate 
& common original. See his memoir *Entwickelungygeschichte der 

Mém. St. Péter: tom. x. 1867, 

of ft in Quart. Journ. Micros. Sei. jo) Profemsor Hacokel's Hi 

a Creation, ii. 152, 200, Fu inf ‘ill be found in chap, ii, of vol, 

Hicot the late Pi Baltour’s Camparntior Embryology, ant an application af the 

facts of dovel t to the philosophy of the subject in (Profesor Ray Lankester's 

Degeneration lon, 1840). 


843 


CHAPTER XVIII 


‘ 
i MOLLUSCA AND BRACHIOPODA 
ls 


f forms of ‘shell-fish,’ with their ‘naked’ or shell-less 
furnish a great abundance of objects of interest to the micro- 

of which, however, the greater part may be grouped under 
theads—namely (1) the structure of the shell, which is most. 
isting in the Concuirera (or LAMELLIBRANCHIATA) and BRACHIO- 
in both of which classes the shells are ‘bivalve,’ while the animals 
from each other essentially in general plan of structure ; (2) 
racture of the tongue or palate of the GasTropopA, most of which 
‘univalve’ shells, others, however, being ‘naked’; (3) the 
pmental history of the embryo, for the study of which certain 
\Gostecpode present the greatest facilities. These three subjects, _ 
lore, will-be first treated of systematically, and a few miscella- 
+ facts of interest will be subjoined. —_ 
hells of Mollusca.—These investments were formerly regarded 
ere inorganic exudations, composed of calcareous particles, 
uted together by animal glue ; microscopic examination, how- 
has shown that they possess a detinite structure, and that this 
tare presents certain very remarkable variations in some of the 
ps of which the molluscous series is composed. We shall first 
‘ibe that which may be regarded as the charucteristic structure 
e ordinary bivalves, taking as a type the group of Margaritace, 
hineludes the Meleagrina or ‘pearl oyster’ and its allies, the 
son Pinna ranking amongst the latter. In all these shells we 

sistingaish the existence of two distinct layers ; an external, 
"beowni yellow colour ; and an internal, which has a pearly 
tecreous ’ aspect, and is commonly of a lighter hue. 
the structure of the outer layer may be conveniently studied in 
hell of Pinna, in which it commonly projects beyond the inner, 
there often forms lamine sufficiently thin and transparent to 
bit its general characters without any artificial reduction. If a 
Uportion of such a lamina be examined with a low magnifying 
er by transmitted light, each of its surfaces will present very 
4h the appearance of a honeycomb ; whilst its broken edge exhibits 
aspect which is evidently fibrous to the eye, but which, when 
‘nined under the microscope with reflected light, resembles that 
assemblage of segments of basaltic columns (fig. 638). ‘This 
ttlayer is thus seen to be composed of a vast number of pri«ms, 





STRUCTURE OF SHELIS 845, 


mevounted for by suj that each is ened by: 
wlditions at its Been ig ot joni of wl m 
acorn ree line pe me thows een 
tel rane not w boy a to 
agile into thin laminw along the lines of striation ; 
nally meet with an excessively thin creerigeanh pe ree 
tho thicker prismatic layers, with 
ave of which it monte have 
probably coalesced, but for some 
wevidental cause which preserved 
its distinctness. That the prisms 
are not formed in their entire 
forsetntey, | agin’ soa 
ty an 
Toosatidated a nae lower ax 
teemities, would appear al 
Hey the fact ops where e 
shell presents a deep colour (as y 
in Pome nigrina) ieee a ‘Gr hearetion of pie zien 
is usually istinet 
aicate: the tutor: mof cach layer being the 
Cinpet) wot et innee eateonidies se iv am ones oe 
[oas, 
‘This * prismatic” ment of the carbonate of lime in the 
shells of Pinne and its allies has been long familiar to concholo- 
wists, and regarded by them as the result of ccyatallimtion, When 











Fin. 638.-Oblique section of prismatic phell-snbxtancw. 


it was first more minutely investigated by Mr. Bowerbank 'and the 
Author,t and was shown to be connected with a similar arrangeuent 
id che membranous residuumleft after the decalcification of the shell- 

substance by acid, microscopists generally agreed to regard it as a. 


1 80n the Structre of the hells of Mllascons and Conchiferous Animals) in 
Vrms. Micros. Sor, ser, i: vol. ip 1844, 
wt the Micro Iructare of Bhalla! i Reports of British Aetoviation tor 
Jotepiud 2547, 
r, Quekete's Histological casabveneeh the Collegeof Surgeons ane, 
wed ie rreshanes on lc toteogty, VOR. ii 





STRUCTURE OF SHELLS 847 


these bei tently no more than yshyyth of Inbecronceis But 
an the sep be tested ie a dilute acid, so us to dissolve its cal- 
careous no such repetition of membranous layers is to bo 
eee: on the contrary, if the piece of nacre be the product of one 
of shell formation, there is but a single Inyer of membrane. This 
layer ewever’ i krvbdlto t a more or less folded or plaited 
arrangement, and the linea! of the nacreous surface may 
be thus accounted for. A similar arrangement is found in 
which are rounded concretions projecting from the inner of 
hes shell of Meleagrina, and possessing a nacreous structure corre- 
to that of‘ mother-of-pearl.’ Such concretions are found in 
many b oes shells, especially the fresh-water mussels, Unio and Ano- 
don ; but these are usually less remarkable for their pearly lustre ; 
and, when formed at the edge of the valves, they may be partly or 





Fi. 639.—Section of nacreons of shall of Meleagrina 
margaritifera (Pear! ye 

even entirely made up of the prismatic substance of the external 
layer, and may be consequently altogether destitute of the pearly 
character. 


Tn all the genera of the Margaritacen we find the external layer 
of the shell ean and of considerable thickness, the internal 
sereribe being nacreous. But it is only in the shells of a few families 

ves that the combination of organic with mineral components 
ett gta pana litte foreni= anal thane ies are for the most 
part nearly allied to Pinna. In the Unionide (or ‘ fresh-water 
mussels ’) nearly the whole thickness of the shell is made up of the 
‘internal or ‘nacreous’ eo ree but a uniform stratum of prismatic 
substance is always found between the nacre and the periostracum, 
constituting the inner layer of the latter, the outer being 
. _ In the Oatreacee: (or oyster tribe), also, the greater 

net the thickness of the shell is composed of m ‘sub-nacreous’ 
substance, ule the inner layer of the shells of Margaritacem, 
its successively formed laminw, however, having very little wdhesion 





eT 


$48 MOLLUSCA AND BRACHTORODA 


to each other ; and every one of these lamina: is be 
eats eee the prismatic substance i 
brownish-yellow colour, In these and some other enses a 
membranous residuum is left after the decaleitication of the 
ere foi the argc) te 0 ne 
wi (ns e “D0 | 
Genoraly speaking, a thin prismatic layer sy he eet 
external surface of bivalve shells, where has been protected 
by # periostracum, or hag been ted in any other manner 
from undergoing abrasion ; thus it is found protty generally: im 
Chama, Trigonia, and Solen, and in Anomia and Mecten. 
In many other instances, like « cellular steve 
| ture can be distinctly seen in the delicate left after deeal- 
cification ; ein eer) oases the: Sntaal|badelbens Weta aed 
proportion to jcareous substance, shell is asually ex~ 
hanl. This hardness ap- 





Hi 








i of 
lime ; for whilst in the prismutie 
and ordinary this 
Sep eS pase hard 

of Pholas to we the arrange- 
pt af arroyo, the difference 
between two: 





= = EF) to be deposited in nodules that 
10. BAO. iow of possess line structure re 

is oe ga crore ae Seiten t ont the mineral 
termed wureellite, Ay to 


this curious arrangement are seen in many other shells, 4 
‘There are several bivalve shells which almost ition of 
what may be termed a suh-nacrrows substance, ny 
surfaces being marked by lines, but these lines being: of 
that regularity of arrangement which is 1 to produce the 
iridescent lustre, ‘This is the case, for example, with most of the 
Peetinider (or scallop tribe), also with some of the Mytilacen (ae 
mussel tribe), and with the common Oyster. En the Baie | 
of by far the greater number of bivalve shells, however, theré is 
the least approach to the nacreous aspect; nor is there 
that can be described as definite structure; and the 
left after its deculcification is usually a structureless “iasement 
membrane.” q 
The ordinary account of the mode of of the shelln of 
bivalve Mollusca— that they are progressive! Rls it fate 
sition of new lamin, each of which is in contact e 


surface of the preceding, and extends beyond it—does not express 





i 


=z 





SHELLS OF LAMELLIBRANCHS 


the whole truth ; for it takes no account of the fact that most 
are composed of two layers of very different texture, and does 
specify whether both layers are thus formed by the ent 
surface of the ‘mantle’ whenever the shell has to be tstended, 
whether only one is uced. An examination of ae 
clearly show the mode in which the operation is effected. This 
Jab eapee ger nearnnptey Rotate iain corte ERS x 
icularly to its surfuce, passing from margin or 
the left bad of the pease ky towards ihe hinge (which would i 
some distance it). ‘This section brings into view the 
two piremoaipthern of which gk aM is composed, traversing the onter 
or pessetis layer in the direction of the length of its prisms, and 
the nacreous lining in such a manner as to bring 
into v ais Seen can saeatel ee arta bee, 
se. These lines evidently indicate the successive formations of this 


Hig 


rte 





F1G, 641,—Vertical section of the lip of ono of the valves of the 
shell of Uw a, bye successive formations of the outer 
prismatic layer; a’, b,c’, the same of the inner naereous layer, 





layer, and it may be easily shown by tracing them, ‘towards the 
hinge on the one side and towards the margin on the other, that at 
every enlargement of the shell its whole interior is lined by a nae 
nacreous lamina in immediate contact with that which 

‘The number of such laminze, therefore, in the oldest part of the Shell 
indicates the number of enlargements which it has un 

outer or ee eriomatis lnyer of the growing shell, on the other hand, ix 
only formed where the new structure projects beyond the margin of 
the old ; and thus we do not find one layer of it overlapping another, 
except t the lines of junction of two distinct formations. When the 
shell has attained its full dimensions, however, new lamina: of both 
layers still continue to be added, and thus the lip becomes thickened 
by successive formations of prismatic structure, each being applied 
to the inner surface of the preceding, instead of to its free margin. 

A like arrangement may ee well seen in the Oyater, with this ditfer- 

ence, that the successive layers have but a comparatively slight 
adhesion to each other. 

The shells of Zerebratule: and of most other Brachiopods ave 
distinguished by peculiarities of structure which differentiate them 
from shies. of the ie, yes ate sections a ian a 
microscopic: examined, they exhibit appearance long flat~ 
tened prisms (ly. 642, A, b), Thich are Peete with such ogy 


eT 


850 MOLLUSCA AND BRACHIOPODA 
that their rounded extremities crop out upon the inner surface of the: 
shell in eee) manner (a). All true Terebratubide, 


recent il, exhibit another r - 
Sean a the Sr hy aie ge meee ee cia 
A B 





Mi internal and 
Frof612.—A, bon es oie motion, 5 A ae raacaiete 


which generally pass esi Agata ey dt ‘one surface to the 
other (as is shown in ver sections, fig. Sr eoneaaae ees 
nally by open orifices ie 642, A), whilst externally they are covered 
by the periostracum (B). Their 
diameter is towards 
the ext surface, where 
they sometimes expand sud. 
peep perry = smal 
pet- it 
arrowed rather suddenly 
arcs as sometines 
a new internal al ayes sae 
as a lini 
(fig: 648, si, oon pedi 


praia in “Tintent tatartiae 
sections of one and the sane 


: F 1, will to 
Fig, 643—Vertical mactions of ahell ot Satd- Shel pees Hid 
‘heimte aairalle sowing nt A the canals the part of Ts thdeknned 

opening by large trampet-shaped orifices the section 

Sid tito eartow treed; sod ahoving } 

a into 

« bifareation of tho canals. species of perforated 
pods, however, present very 
striking diversities in the size and closeness of their canals, as shown 
by sections taken in corresponding parts; three exam, ae 
kind are given for the sake of comparison in 
canals are occupied in the living state by tul Petts of 
the mantle, whose nee is filled wie a fluid containing 
cells and granules, which, from its corresponding it Pape aoe 
the fluid contained in the great sinuses of the may perhaps 





SHELLS OF BRACHIOPODA 851 


‘be considered to be the animal's blood. Of their special function in 
the economy of the animal it is difficult to form I iden ; 
but it is interesting to remark (in connection with vot 
arelationship between and ) that they seem to 
have their 1 in extensions of the perivisceral cavity of iy 
Rewalls of the ‘cals of tha Polyscry.Prosene Golan fod 
walls of the cells of the polyzoary, Solas! finds 
Ltn Ulead cane merino fibre which can be traced 
backwards to the nerve-cells of the mantle ; at the distal end is a 
terminal cell which is connected by a fibril with the axial fibre, and 
is covered by a transparent chitinous layer ; save for the 
absence (or the unproved presence) of pigment cells we should be 
Sree Upmaye dbemd ote oie els aN 


luminous im) ‘ions, 
Tn the family. Jhynchoneltide which is represented by only 





Pro. 45. Pro, 46, 


Fa, O44.—Horizontal section of shell of Terebratuia buliata (fossil, Oolite), 
Fro, 645, a a Meyertia tina (foal, Chalk). 
Fro. 046. S . Bpiriferina rovtrata (Teinasic)- 


‘six recent species, but which contains a very large proportion of 
fossil Brachiopods, these canals are almost gear absent ; 50 
that the uniformity of their presence in the Terebratulide, and their 

absence in the Rhynchonellide, supplies a character of 
great value in the discrimination of the il shells belonging 
to these two groups respectively. Great caution is necessary, 
however, in applying this test; mere euxfice markings cannot 
relied on ; sa no statement on this point is worthy of reliance 
which is not based on a microscopic examination of thin sections of 
the shell. In the families Spirjforide: and Strophomenider, on the 
other hand, some species posse=s the perforations, whilst others are 
destitute of them ; so that their presence or absence there serves only 
to mark out subordinate groups. This, however, is what holds good 
in regard to characters of almost every description in other depart- 
ments of natural history; a character which is of fundamental 
importance from its close relation to the general plan of organisation 
in one ap, being, from its want of constancy, of far less account 
in x 


1 Pree, Roy. Dublin Soc. ¥. 813. ’ 

Fea er nmise nconont of the Auilict's resserches on this proup nea hia mneaiele 
‘om the subject, forming part of the introduction of Mr. Davidse n's Mf im of Cae 
x ae 





4 





SHELLS OF MOLLUSCA 853 


a. pihey may be separated from the soft tissue in which 
3 imbed. by means of caustic potash ; and when treated 
bate acid, whereby the calcareous matter is dissolved away, 
anic basis is left, retaining in some degree the form of the 
Aspicule. This basis seems to bea cell in the earliest stage of 
ration, being an isolated particle of protoplasm without wall 
, and the close correspondence between the appearance pre- 

thin sections of various univalve shells, and the forms of 
of Doris, seems to justify the conclusion that even the 
ypact shells of this group are constructed out of the like 
im a state of closer aggregation and more detinite arrange- 
the occasional occurrence of a layer of more spheroidal 
of the same kind, like those forming the vestigial shell of 


bpar 


F 
e 


structure of shells generally is best examined by making 
in different planes as nearly parallel as may be possible to 
lerfaces of the shell, and other sections at right angles to these ; 
may be designated as horizontal, the latter as vertical. 
need be added to the full directions for making such 
‘which have already been given. Many of them are beautiful 
ing objects for the polariscope. Much valuable informa- 
also be derived from the examination of the surfaces pre- 
re, The membranous residua left after the decalci- 
the shell by dilute acid may be mounted in weak spirit or 

’s solution. 
enimals composing the class of Cephalopoda (cuttle-fish and 
tribe) are for the most part unpossessed of shells ; and the 
of the few that we meet with in the genera Vautilus, Aryo- 
(‘paper nautilus’), and Spirula does not present any peculi- 
that need here detain us. The rudimentary shell or sepiostaire 
Ihe common cuttle-fish, however, which is frequently spoken of as 
‘cuttle-fish bone,’ exhibits a very beautiful and remarkable 
such as causes sections of it'to he very interesting micro- 
objects. The outer shelly portion of this hody consists of 
layers, alternating with calcified layers, in which last may be 
an hexagonal arrangement somewhat corresponding with that 
in fig. 640. The soft friable substance that occupies the hollow 
boat-shaped shell is formed of a number of delicate calcareous 
running across it from one side to the other in parallel 
but separated by intervals several times wider than the 
of the plates ; and these intervals are in great part filled 
‘what appear to be fibres or slender pillars passing from one 
or floor to another. A more careful examination shows, 
, that, instead of a large number of detached pillars, there 
@ comparatively small number of very thin sinuous laminw, 
from one surface to the other, winding and doubling upon 
welves, so that each lamina occupies a considerable space. Their 
“+e arrangement is best seen by examining the parallel plates, 
the sinuous lamine have been detached from them, the lines 
L ‘ction being distinctly indicated upon these. By this arrange- 
sé cach layer is most effectually supported by those with which 


Hye 

























— 


PALATES OF GASTROPODA 855 


far beyond the head, which ma; 





cavity, between the greatl \ 
foot : and in some species its length is twice or even three times as 
great as that of the entire animal. Ina of cases 
these palates exhibit a very marked separation the central 
and the lateral portions (figs. 
649, 850), the teeth of the cen- 
tral band being frequently small 
and smooth ut their edges, 
whilst those of the lateral are 
lange and serrated. The palate 
of Trochus sizyphinus, repre- 
sented in fig. 649, is one of the 
most beautiful examples of this 
form, not only the large teeth 
of the lateral bands, but the 
delicate leaf-like teeth of the 
central portion baving their 
edges minutely serrated, A yet 
more complex type, however, is 
found in the palate of /aliotis, 
in which there is a central band 
of teeth having nearly straight Fi, 619.—Palate of Trochax alzyphinws. 
edges instead of points; then, on 

each side, a lateral band evnsisting of large teeth shaped like those 
of the shark; and beyond this, again, another lateral band on either 
side, composed of several rows of smaller teeth. Very curious 
differences also present themselves among the different s of 
the same genus. Thus in Dorie pilosa the central band is almost 
entirely wanting, and each lateral band is formed of a single row 
of ay large hooked teeth, set obliquely like those of the lateral 
band in fig, 649; whilst in Doris tuberculata the central band is 
the part most developed, and contains a number of rows of conical 














DEVELOPMENT OF MOLLUSCA 857 


membrane that forms the sheath of the tube, when this is thick 
enough to interfere with its transparence. The tube itself should be 
slit up with a pair of fine scissors through its entire length, and 
should be so opened out that its expanded 
surface may be « continuation of that 
which forms the floor of the mouth. The 
mode of mounting it will depend upon the 
manner in which it is to be viewed, For 
the ordinary purposes of microscopic ex- 
amination no method is so good ax mount- 
ing in fluid, either weak spirit or Goadby's 
ution answering very well. But many 
of these palates, expecinily those of the 
marine Gastropods, become most beautiful 
objects for the polariscope when they are 
mounted in Canada balsam, the form 
and arrangement of the teeth being very 
strongly brought out by it (fig. 651), and 
a gorgeous play of colours being exhibited 
when a selenite plate is placed behind the 
object, and the analysing prism is made to "%2;,SLjDalate of | Bust 
rotate.! polarised light. 
Development of Molluscs. —Leaving to 
the scientific embryologist the large field of study that lies open to 
him in this direction,’ the ordinary microseopist will tind much to 
interest him in the observation of certain special phenomena of 
whieh « general account will be here given. Attached to the gills of 
fresh-water mussels (Unio and Anodon) there are often found in the 
spring or early summer minute bodies which, when first observed, 
were described as parasites, under the name of G/ochidia, but are 
now known to be their own progeny in an early phase of develop- 
ment. When they are expelled from between the valves of their 
parent, they attach themselves in a peculiar manner to the fins and 
gills of fresh-water fish. In this stage of the existence of the young 
Anodon, valves are provided with curious barbed or serrated 
hooks (fig. A), and are continually snapping together, until 
they have inserted their hooks into the skin of the tish, which seems 
80 to retain the barbs as to prevent the reopening of the valves. In 
this stage of its existence no internal organ is detinitely formed, 
except the strong ‘adductor’ muscle (aad) which draws the valves 
together, and the long, slender byssus-tilament (4y) which makes 
its appearance while the embryo is still within the egg-mem- 
brane, lying coiled up between ‘the lateral lobes. The hollow of 
each valve is filled with a soft granular-looking mass, in which 
istinguished what are perhaps the rudiments of the 















1 For additional details oo the organisation of the palate aud teeth of the 

pod molluscs, wee Mr. W. Thomeon in Cyclop. Anat. and Phywiol, vol. i. 

pp. 1142, 1143, and in A ser. 4i. vol. vii. p. #0; Professor Eroschel, Das 
obias der Sehnecken, Berlin, A. Rileker, ‘Ueber die Bild 
bei Heliz pomatia,’ Bericht oberhess, Gevellsch. Giessen, xxii. p. 209; 

the Mechanism of the Odontophorw in certain Molluscs,’ 7) L 

7 See Balfour's Comparative Embryology, vol. i. ch 






























DEVELOPMENT OF DORIS 859 


the emersion of the embryo, owing to the extreme trans- 
the nidamentum and of the egg-membranes themselves. 
which will be noticed by the ordinary observer is 
ion ’ of the yolk-mass, which divides itself (after the 
‘@ cell undergoing binary subdivision) into two parts, each 
into two others, and so on until a morula, or mulberry- 
of minute yolk-segments, is produced (fig. 653, A-F), 
feonverted by ‘invagination’ into a ‘gastrula,’ whose form 


‘Wrs. 658.—Embryonic development of Doris bilamellata: A, ovum, consist 
‘ag of enveloping membrane, a, and yolk, b; B, C, D, E, F, successive 
of segmentation of yolk; G, first marking out of the shape of the 
; H, embryoon the eighth day ;I, the same on theninth day; K, the 
tame on the twelfth day, seen on the left side at L; M, still more advanced 
seen at Nas retracted within its shell ; @, position of shell-gland; 
46, ciliated lobes; d, foot; g, hard plate or operculum attached to it; 
A, stomach ; i, intestine; m, m, masses (glandular?) at the sides of the 
8; 0, heart (2); 2, retractor muscle (?); #, situation of funnel; 

5 ‘snveloping the body; z, auditory vesicles; y, mouth. 








DEVELOPMENT OF PURPURA 861 


The disappearance of the cilia has been observed by Mr. Hogg 
eoincident with the development of the teeth to a d suf- 
& to enable the young water-snail to crop its vegetable food ; 
ve has farther ascertained that if the growing animal be kept in 
water alone for some time, without vegetable matter of any 
the gastric teeth are very imperfectly developed, and the cilia 
ill retained.' 

.Wery curious modification of the ordinary plan of development 
sented in Purpura lapillus, and it is probable that something 
» same kind exists also in Buccinwm, as well as in other Gas- 
ds of the same extensive order (Pectinibranchiata), Each of 
mpeules already described contains from 500 to 600 egg-like 
ww (fig. 654, A) imbedded in a viscid gelatinous substance ; but 
from twelve to thirty embryos usually attain complete develop- 
i, and it is obvious, from the large comparative size which: these 
B (fig. 655, B), that each of 

4 must include an amount of » e D 
tance equal to that of a great @ @ Bi e 
ber of the bodies originally 

wd within the capsule. The 

lanation of this fact (long = iA < ™ 
wnoticed by Dr. J. E. Gray 

mgard to Buccinum) seems to ® 

aa follows. Of those 500 or 

Frerike bodies, only a small 


: F 7 
are fertile ova, the remainder 

hg unfertilised ‘eggs, the yolk ; @ 

Weal of which serves for the ; 


kkition of the embryos in the Fio, 951—Early stages of embryonic 
fwestages of their intracapsular development of Purpura lapillu 
The distinction between  ¢se-like spherule; B. C E, F, G 
& manifests itself at a very {pheruleu: D, H, 1, J, K, suecew 
period, even in the first — stagesof development of early embryos. 
Rentation ; for, while the latter 
de into two equal hemispheres (fig. 654, B), the fertilised ova 
de into a larger and a smaller segment (D); in the cleft between 
te are seen the minute ‘directive vesicles,’ which appear to he 
ays donble, although, from being seen ‘end on,’ only one may 
visible; and near these is generally to be seen a clear space 
ach segment. The difference is still more strongly marked in 
subsequent divisions ; for, whilst the cleavage of the infertile 
4 goes on irregularly, so as to divide each into from fourteen to 
nty segments, having no definiteness of arrangement (C, E, F, (), 
tof the fertile ova takes place in such a manner as to mark out 
distinction already alluded to between the ‘cephalic’ and the 
weral’ portions of the mass (H). and the evolution of the 
ner into distinct organs very speedily commences. In the first 
ance a narrow transparent border is seen around the whi 
wryonic mass, which is broader at the cephalic portion (I); next, 









1 See Trans. Micros. Soc. ser. ii. vol. ii, 1854, p. 98. 








shell ; and the mass of yolk-segments of which the is made uj 
etl apn no he ars bo pr bret 


tion, &e., the evolution of which (and while they areas yet far 
from ia eee the capsule thins away at its summit and the embryos 
make escape from it.’ 

Tt happens not unfrequently that one of the embryos which 1 


the rudiment of a body, may be seen in active motion among then. 
Pineda epee pedrer green a ) Neate a ie 
within the same capsule, especially if their number should be con- 
siderable , for it sometimes appears as if there were not food enough: 
eee Faia Ce Se eee and : 


deficient in any of their organs ; and others, agnin, are more or lees 
completely abortive—the supply of supplemental yolk which they 
have obtained having been too small for the development of their 
viscera, alth it may have afforded what was led for that of 
the ciliated lobes, eyes, tentacles, auditory vesicles, and oven the 
foot—or, on the other hand, no additional supply whatever havi 

bean acquired by them, so that their development has been Festi | 
at a stil earlier ‘These phenomena are of so remarkable a 
character that eee mets anal Lash oes of Biba a to any 
microscopist who ma n to in; mont August 
and Repeater: ina Tosaliey in which “the Paint abounds ; since, 
by ease a sufficient number of capsules, no difficulty need be 
experienced in arriving at all the facts which have been noticed in 
this brief summary.? It is much to be desired that such microseopists 


‘the two ends of the jule (taking care not to cut far into its cavity), 

sad in then forcing « jot of water it by inserting the end of a fine-pointed 

‘one of the orifices thus mado, so as to drive the contents of the capsule 

before it through the other. ‘Theao should be received into a ¢hallow cell and fires 

examined under the simple microscope. For some observations on the de- 

‘walgpouenh of Purpura, ove Prolessr Hadden, “Notes en the Developanent of the 
inieea,! a “ i. 


‘867. 
{a in the Author's account of hia re- 
Mera.” vol i, 15, pT. "His enum of the 
was called juost y 
Tinesau ebiirely diferent version of \t, Dub was fully consirmed by the otwervatlons 
of Dr. Dyster. See Ann. Nat. Hist, ser. ii. vol. xx. 1857, p 16, “The independent 










SENSE-ORGANS OF MOLLUSCA 865, 


uous witha layer of pigment lining the sclerotic, a crystalline 
vitreous body, and a retinal expansion proceeding from an 
verve which passes to each eye from the trunk that runs along 
argin of the mantle.' Professor H. N. Moseley has made the 
sting discovery that many of the Chitonide are provided with 
© number of minute eyes on the exposed areas of the outer 
es of their ahells ; as the fibres of the optic nerve are directed 
rods from behind these eyes are of the ordinary invertebrate 
and differ therein from the just mentioned eyes of Pecten, or 
which are found on the back of Onchidium, which resemble 
wtebrate retina in having the optic tibres inserted into the front 
sof the layer of rods? Eyes of still higher organisation are 
upon the head of most Gastropod molluscs, generally at the 
x€ one of the pairs of tentacles, but sometimes, as in the Snail 
Rug, at the points of these organs. In the latter case the ten- 
tare furnished with a very peculiar provision for the protection 
peyes ; for when the extremity of either of them is touched it 
wn back into the basal part of the organ, much as the finger of 
we may be pushed back into the palm. The retraction of the 
tele is accomplished by a strong muscular band, which arises 
im the head and proceeds to the extremity of the tentacles ; 
oe hea protrusion is effected by the agency of the circular bands 
twhich the tubular wall of the tentacle is itself furnished, the 
portion being (as it were) squeezed out by the contraction 
lower part into which it has been drawn back. The structure 
eyes and the curious provision just described may easily be 
by snipping off one of the eye-bearing tentacles witha pair 

. None but the Cephalopod molluscs have distinct organs 

ing ; but rudiments of such organs may be found in most 
(fig. 653, K, xx), attached to some part of the nervous 
surrounds the cesophagus, and even in many bivalves, in 
with the nervous ganglion imbedded in the base of the 
‘These ‘ auditory vesicles,’ as they are termed, are minute suc- 
each of which contains o fluid, wherein are suspended a number 
inute calcareous particles (named otoliths, or ear-stones), which 
‘kept in a state of continual movement by the action of cilia 
lg the vesicles. This ‘wonderful spectacle,’ as it was truly 
(uated by its discoverer Siebold, may be brought into view 
it any dissection by submitting the head of any small and not 
 thick-skinned Gastropod, or the young of the larger forms, to 
te compression under the microscope and transmitting a strong 
tthrough it. The very early appearance of the auditory vesicles 
heembryo Gastropod has been already alluded to. Those who 
8 the opportunity of examining young specimens of the common 
‘en will Sind it extremely interesting to watch the action of the 
rdelicate tentacles which they have the power of putting forth 


be front, and to possess 8 coloured iris (having a pupil) that 


See Mr, 8. J. Hickson on ‘The Eye of Pecten' in Quart. Journ. Micros. Sci. 
Xx. ms. 1880, p. 448. 
‘Gee Professor Moseley ‘ On the Presence of Eyes in the Shella of certuin Chitonider, 
a the Structure of these Organs,’ in Quart. Journ. Micros. Sci. xxv. p. 37. 
3K 





867 


CHAPTER XIX 


WORMS 


fm the general designation of Worms naturalists at present 
ipa number of Metazoa, which differ considerably among them- 
iu and exhibit on the one hand very simple, and on the other 
complex plans of organisation ; the assemblage is, indeed, 
anything else than a zodlogical lumber-room, from which, 
‘the progress of research, group after group may be expected to 
ed. Among others there are included in it the Entozoa or 
worms, the Rotifera or wheel animalcules, 7'urbellaria, and 
each of which furnishes many objects for microscopic 
tion that are of the highest scientific interest. As our 
however, is less with the professed physiologist than with 
1 inquirer into the minute wonders and beauties of Nature, 
over these classes (the Rotifera having been already 
in detail, Chapter XIII) with only a notice of such points as 
ly to be specially deserving the attention of observers of the 
order. 
















—This term is one which has been applied to such worms 
parasitic within the bodies of other animals, and which obtain 
mutriment by the absorption of the juices of these, thus 
a striking analogy to the parasitic Fungi.! The most re- 
le feature in their structure consists in the entire absence or 
extremely low development of their nutritive system, and the 

inary development of their reproductive apparatus. Thus 
tae common Tenia (‘tape-worm’), which may be taken as the type 
the Cestuid group, there is neither mouth nor stomach, the so-called 
‘ad’ being merely an organ for attachment, whilst the segments of 
‘body’ contain repetitions of a complex generative apparatus, 
‘male and female sexual organs being so united in each as to 
ible it to fertilise and bring to maturity its own very numerous 
fu; and the chief connection between these segments is established 
two pairs of longitudinal canals, which appear to represent the 
ter-vascular system,’ whose simplest condition has been noticed 
the wheel-animalcule. Few among the recent results of micro- 





% The most important work on human entozoic parasites is that by Professcr 
Wekart, Die menschlichen Parasiten, of which a second elition ia now in courre 
ication ; of this—the first portion has already becn translated into Enzlich 
. W. EB. Hoyle. , 
K 











i 


Ce moist 
and sometimes also in canals of snails, frogs, fishes, 


egaegee 
Al 
PeSeece 
He 
Fiuetil 
THe 
phe é 
A u 
Bs — 

a 
Hel 
aec8 

peal 


bs 

$ 

: 

2 

aif 
PEE 
Fee 

aes 


Fy 
é 
y 
a 
2 
i 
i 
H 


( 
are being developed jually assumes the appearance of 
sea if ibe ided the interior will he found. 
com ly with a dense white cottony mass, oceupying t 
place of the flour, and leaving merely a smull place for a little 
glutinous matter. The cottony substance seems to the eye to consist 
of bundles of fine fibres closely packed together ; but on ib 
a small portion, and putting it under the microscope with a little 
water under a thin glass cover, it will be found after a short time (if 
being really Anguillule or ‘eels’ of the mi If the seeds 
be soaked in water for a couple of hours before are laid 1) 
the eels will be found in a state of activity from the first ; thei 
movements, however, are by no means so energetic as the 
A, glutinis or ‘paste eel,’ This last frequently makes its appearance 
spontaneously in the midst of paste that is turning sour; but the 
best means of securing a supply for any occasion consists in allowing 
a portion of any mass of paste in which they may present themselves 
to dry up, and then, laying this by so long as it may not be wanted, 
to introduce it into a mass of fresh paste, which if it be kept warm 
and moist will be found after a few days to swarm with these curious 
little creatures. 

Besides the ing orders of Entozoa, the Z'rematode group, 
which is more closely allied to the Cestoda than to the Nematodes 
must be named ; of this the Distoma hepatioum, or ‘fluke,’ found 
in the livers of sheep affected with the ‘rot,’ is a typical example. 
Into the details of the structure of this animal, which has the 

neral form of a sole, there ix no occasion for us here to enter ; 
is remarkable, however, for the branching form of its diges- 
tive cavity, which extends throughout almost the entire body, very 
much as in the allied Planaria ri 656) ; and also for the curious 


i 
i 
i 
in 


23) 
e 












in the light of err stem, the of 
which is not only 5 pe 13 Both sets of 
‘organs are combined in hough ‘tn congress. 


oak ingen ne ou tte stems to be gene- 
ovatla, aa in the renee extend Bd Usage 


Bercy tinct es aes ote 


about the history of the em- 
bryonic development of these 
animals, as the accounts given 
of it by different observers ‘2 
no means harmonise with esc 
oer The carers how- 
ever, do not mu! eggs 
alone; for they “ ly un- 
taneous fission in a 
transverse direction, each 


ment becoming a imal ; 
and an arti division into 
two or even more may be 


tised with n like ee In 
ge power of the Lena 
luce rtions wl 

ae, been wees seems but 
little inferior to that of the 
Hydra; % circumstance which 
is een ita remarkable when 
character of 


tin is borne in 
a distinet. 


fn of ae gla Wh, f). 
various parts of the ody an 
in the neighbourhood of these 
are usually to be observed a 
namber ( (varying from two to 
forty) of é or rudimentary 
eyes, each having its refracting 
body or crystalline lens, its pig- 
ment-layer, its nerve-bulb, and 
its cornea-like bulging of the 
skin, The integument of many 
= seers a reat idles whic possibl 
wit containing or spin which are very ly 
comparable to the ‘ thread-cells' See meyiact 

1 

2 For fnthe igarmion rsnrding too Perbelare consalt Br. L: Grantee 
on Planariana in tho 9th edition of | the eater Diritannécd, ase Bis meen 

sonegraahie ia der Tuerbeliari ee; A. Lang, Die 
P. Halles, Contrity istoire wat dies Puri 
Gn traneverss Sinsion, we Boll, Journ. Roy. Micros. Soc. (2), vi. p. THOT. 








DEVELOPMENT OF WORMS ; 


a3 
communicates with a central ‘organ, and not only carries 
pon Petes gah 


EI 


“1 


for the first is transmitted . tentacles which sur- 
round the mouth (fig. 657, 2, b), whilst the second circulates throu 
the beautiful arborescent gill-tufts (A, #) situated just behind 
head. The former are covered with cilia, the action of which con- 
tinually renews the stratum of water in contact with them, whilst 
the latter are destitute of these organs ; and this seems to be the 
general fact as to the several appendages to which these two fluids: 
ave respectively sent for aeration, the nature of their distribution 
Speareetts of the benstifal specs pestis Soe rebpetery 
ol ut 

circulation of We aah bane Se aeaneet Solara inane 
SE res eae an in tl patti OF Rs Sec Gee 
interior of their bodies (where this is rendered possible by their 
transparence) the mi ‘ist will find a most fertile source of 
interesting occupation ; and he may easily, with care and 


make many valuable additions to our present stock of know! on 
these points. ‘There are many of these marine Annelids in which 
the appendages of various kinds put forth from the sides of their 


of 
bodies furnish very beautiful microscopic objects; as do also the 
different forms of teeth, jaws, &c. with which the mouth is com- 
monly armed in the free or non-tubicolar species, which are 
ox 


Tee tialp Missey oF carseot of Annelids, 
early hil Gy ent nelids, too, is ex- 
tremely curious ; for they come forth from the egg in « condition 
very little more advanced than the ciliated gemmules of 

consisting of w globular mass of untransformed cells, parts 
of whose surface are covered with cilia, which ordinarily become 
arranged in one or more definite rings ; in a few hours, a 
this embryonic mass elongates, and the indications of a ental 
division become ay t, the head being (ns it were) marked off 
in front, whilst behind this is a large segment thickly covered with 
cilia, then a narrower and non-cilinted segment, and lastly the 
eaudal or tail-segment, which is furnished with cilia. A. little 
Tater a new segment is seen to be interposed in front of the 
eauda}, and the dark internal granular mass shapes itself into the 
outline of an alimentary canal.!’ The number of segments pro- 
gressively increases by the interposition of new ones between the 
eaudal and its preceding segments; the various internal organs 
become more and more distinct, eye-spots make their appearance, 


© A most curious transformation once occurred within the Author's 
Gio ae olan. Annolid, which sua fumed with a broad coll or dts. 
cilia, som merely an appearance of segmentation im 4 
cree pee anebres i during which it was not under obserral 
laren assumed the ordinary form of «marine worm three or four times ite pre 
vious length, nnd the ciliated disc entirely dixappeared. An nocident unfortonately 
prevented the more minute examination of this worm, which the Author would have 








LARVE OF WORMS 875 


> be a Gephyrean worm (Phoronis).! An even more extra- 
Wy. departare from the ordinary type is presented by the larva 

received the name Pilidium (fg. 659), its shape being 
ta helmet, the plume of which is replaced by a single long 
-like appendage that is in continual motion, its point moving 
and round in a circle. This curious organism, first noticed 
tannes Miiller, has been since ascertained to be the larva of 








Fra. 6:9.—Pilidium gyrane: A, young, showing at a the alimenta: 
canal, and at b the rudimentof the Nemertid; B, more advan 
stage of the samo; C, newly freed Nemertid. 





species of the Nemertine worms, which belong to the division 
@, a group in which there are no stylets to the proboscis. 

nong the animals captured by the tow-net the marine 
ist will not be unlikely to meet with an Annelid which, 
igh by no means microscopic in its dimensions, is an admirable 
% for microscopic observation, owing to the extreme trans- 


Jeber Pilidium und Actinotrocha’ in Miiller's Archiv, 1854, p. 298. For 
cent observations upon this interesting creature, see Balfour's Comparative 
pp. 299-802 ; and a paper on ‘ The Origin and Significance of the 


yee ctinotrocha,’ by Mr. E. B. Wilson (of Baltimore), in Quart. 
ficros. Sci. April 1881. 


@ especially Leuckart and Pagenstecher's ‘ Untersuchungen tiber niedere 
te’ in Milller’s Archiv, 1868, p. 569; and Balfour, op. cit. p. 165. The Author 
fBently met with Pilidium in Lamlash Bay. 














i ie 
onwards into a tail-like prolongation, the length of which varies 


ase oee as it is contracted or extended, This prolongat 
sea ror five pairs of pers to 


the intestine is continued to awed rae sera 
tobe rp sm contin ofthe by 
porn ienapsher i dary di tise ee as 
cells: wi Ton) el er & sul 

of at this are two ] 


, b), each bearing a double Se anpeere lens-like body, 
oll rudimentary, eyes ; whi bedded in its anterior por- 
tion are two peculiar nucleated vesicles, a, «, which are probably 
the rudiments of some other sensory organs. On the under side ot 
the head is situated the mouth, which, like that 
Annelids, is furnished with a sort of 
or drawn in; a short nade to au elongated 
stomach, which, when: distended with fluid, occupies the whole 
cavity of the central portion of the body, as shown in fig. B, bat 
which is sometimes so empty and contracted as to be like a mere 
cord, as shown in fig. C. In the caudal Fea tiaere neal it is 
always narrowed into an intestinal Ca this, when the mupettige 
isin an extended state, as at C, is rae straight ; but w! 
ppeaadare’s is contracted, ag seen at B it is thrown into conyolutions. 
periviseeral cavity is oooupied :by my fluid, in which some minute 
corpuscles may be distinguished these are in motion 
cilia which clothe some parts at the outer surface of the alimentary 
canal and line some part of the wall of the body. No other more 
atom apparatus, either for the circulation or for the aération of 
nutrient fluid, exists in this curious worm, unless we are to 
dns miheres! so LS the respiraicay ri Runstlps the ciliated canal 
may observ in enol eo a ndages except 
us five pectocioe pairs. This canal commences jes orifices: at 
= pacepee greed nea tay § E, }, and on a larger scale 
at fig. D ; each of these orifices (D, a, }) is surrounded by a sort. of 
Peete, and tho, onette of the Inger ove (0) i 8 with 
radiating ciliated ridges, The two branches incline towards each 
other, and unite into a single canal that runs along, for some dis- 





=e 








878 Worms: 

‘tance in the wall of the body, and then terminates in th 

cavity, and the direction of the motion of the cili 
selene dea Males : 





: of 
stage they usually fill the perivisceral 7, not only of the: 

pes reece eareinel eri j and they trom 
it through transverse fissures which form in the outer w af the 


body at the third and fourth segments. The 
on the other hand, are limited to the c ! 
ae the sperm-cells are developed within the | nted append- 
ages, as the rgells of: the Semele ore iia eee 
the body. Instead of being set free, however, into the peri 
cavity, they are retained within a saccular orang 


(A, 4, @) which fills up the whole cavity of idage ; and 
within this erin fe ie be observed, wi a 
active movement wy make their escape externally by @ passage 
‘that seems to communicate with the smaller of the two just men- 
tioned rosettes ; but they also appear i 
cavity by an aperture that forms i 
of the f Sige tis cataeaaereh - tozoa through the 
of the female by the entrance of 5 
canals, or after Cera made toiieiecape i 
been ascertained. Of the earliest stages of exabeyonie dene 
nothing whatever is yet known ; but it has been tained that 
the animal passes through » larval form, which differs from the 
adult not frosted in the number of the 3 
successively augment by additions at the posterior 
also in that of the ripe, At G is represented the 
hitherto met with, enlarged as much as ten times in 
the adult at B; and here we see that the head is destitute 
frontal horns, but carries a pair of setigerous antennw, a, 
which there are five pairs of bifid Spence i 
first of which, one of ined sees wi aaa In 
more advance it or ten segments developet 
into a second pair of antenna resembling the first; and the animal 
in this stage has been described saa distlact species, 0 
Ata more advanced age, however, the second pair attains the 
enormous development shown at B, andthe first or larval n 
disappear, the setigerous portions separating at a sort of 5 
@), whilst the basal projections are absorbed into the | 
of the body. This beautiful creature has been met with on so many 
parts of our coast that it cannot be considered at all ancommon, 
° 





i: 
i 


il 










al 








produced an electric 
through a tube ite telly tat pensvaley a 
Ss ene a ripest aca for an instant only, eh 
ing ly excl yy any irritation’ to 
oere the itinel Gaheen seintillations may be Besar under 


the "mii even in separate segments, when they are subjected 
to the irritation of a needle-point or a gentle ster vbaaeres 
ascertained by the careful observations of M. de that 


they are given out by the muscular fibres in the act of contraction? 
Among the freshwater Annelids those most interesting to the 
microscopist are the worms of the Vais tribe, which are common in 
our rivers and ponds, living chiefly amidst the mud at the bottom, 
and especially among the roots of aquatic plants, Being blood-red 
in colour, they give to the surface of the mud, when 
themselves from it in large numbers and keep the protruded portion 
of their bodies in constant undulation, a very liny appearance ; 
but if disturbed they withdraw themselves suddenly and completely. 
‘These worms, from the extreme transparency of their bodies, present 
peculiar facilities for microscopic examination, and especially for the 
study of the internal circulation of the red liquid commonly con- 
sidered as blood. There are here no external respirator and 
the thinness of the general integument appears to supp! needful 
facility for the asration of the fluids. One Decrevisiclac ‘trunk (dorsal) 
may be seen lying above the intestinal canal, and another (ventral) be- 
neath it, and each of these enters a contractile dilatation, or heart- 
like o1 situated just behind the head. The fluid moves forwards 
in thedorsal trunk as far as the heart, which it enters and dilates ; 
and when this contracts it propels the fluid ly to the head and 
ey to the ventral heart, which is distended by it. The ventral 
contracting in its turn, sends the blood backwards along the 
ventral trunk to the tail, whence it passes towards the head as 
before. In this circulation the stream branches off from each of 
the principal trunks into numerous vessels proceeding to different 
parts of the body, which then return into the other trunk ; and 
there is a peculiar set of vascular coils, hanging down in the peri- 
visoeral cavity that contains the corpusculated liquid representing: 
the true blood, which seem specially destined to convey to it the 
! See the memoirs of tho Author and M. Clapartde in vol. xxii. of the Linnean 
Transactions ani the outhorities there referred to; also a recent memoir by Dr. F, 
Veldarahy in Zestechrift f. Wien. Zook. Ba, xxx 878, 
‘See hin memoirs on the Annelida of La Munche’ in Aun. des Sei. Naf. ser. ii. 
Mond. Yom, xix. aout se. ik Zool. tou. xiv.; and Professor Mointosh in Nature, 
i De 





2 881 


CHAPTER XX 
CRUSTACEA 


to the division of Arthropods, ,in which the body is 
with distinctly articulated or jointed limbs, some of which 
ys modified to serve as mouth-organs, we come first to the 
of Crustacea, which ordinarily includes (when used in its 
jeomprehensive sense) all those animals belonging to this group 
are fitted for aquatic respiration, though the king-crab 
}) has closer relations to the scorpions, and the Pycnogonids 
Mhe spiders. It thus comprehends a very extensive range of 
; for although we are accustomed to think of the crab, lobster, 
fish, and other well-known species of the order Decapoda (ten- 
), as its typical examples, yet all these belong to the highest 
many orders ; and among the lower are many of a far simpler 
es and not a few which would not be recognised as belonging 
class at all were it not for the information given by the 
Ry of their development as to their real nature, which is far more 
Sarent in their early than it is in their adult condition. Many 
Qe inferior kinds of Crustacea are so minute and transparent 
%@ their whole structure may be made out by the aid of the 
without any preparation ; this is the case, indeed, with 
tly the whole group of Entomostraca, and with the larval forms 
bm of the crab and its allies ; and we shall give our first atten- 
im to these, afterwards noticing such points in the structure of the 
wer kinds as are likely to be of general interest. 
‘A curious example of the reduction of an elevated type to a 
simple form is presented by the group of Pycnogonida, or no- 
% crabs, some of the members of which may be found by atten- 
ve search in almost every locality where sea-weeds abound, it 
ing their habit to crawl (or rather to sprawl) over the surfaces of 
wse, and probably to imbibe as food the gelatinous substance with 
hich they are invested.' The general form of their bodies (fig. 
$1) usually reminds us of that of some of the long-legged crabs, 
w abdomen being almost or altogether deticient, whilst the head is 
try small, and fused (as it were) into the thorax ; so that the last- 
gmed region, with the members attached to it, constitutes nearly 
bbe whole bulk of the animal, The head is extended in front into 
+1 is remarkal v forms of this group, somotinicn i 
imevihanErelve inches ecvoe’ have ben brought from int der ea 
L 











with the l-inch, Lent Or -inch jets ue a tape 
driy step aeat le sit t tl them, and this. 
to drive a large quantit to to 
Je ea is eae ment 
Entomostraca.—' ip of crustaceans, many of the existing 
members of which are arn cade minute ut an af be only jon visible to 
— ‘yf tha apenages ren yn fagcih rap 


bear, and to the mode in which these Peay to the 
glee feo es 
6 yy a small num! legs not five 
have their function limited to locomotion, the respiratory organs 
being to the parts in the neighbourhood ‘of the mouth ; 
whilst in the Sranchiopoda, or ‘ gill-footed’ ae the members 
as ‘fin-feet’) serve both for locomotion and for respiration, 
and the ‘number of these is commonly large, bein; Apue as aa 
as sixty pairs, The character of their dopt shares Ha according! 
for whilst all the members of the first-named tribe dart through 6 
water in « succession of jerks, so as to have acquired the common 
name of ‘ water-fleas,’ those among the latter which possess a great: 


"$B 


¥ Certain points af resemblance borne we Pycnogonida to spiders make the 
careful stody of their eeckbinenes & matter 


‘interest an 
eee mere peace, ta regan! the air at rach adapted a 
The q 
ids ap A Gohen'a Die Pantopoden dee Golfes von Ne 
DP. nen ph 


diosa feats Ds P.P, C Hoes Report on tho 
Ts a Nouvel Eros int los Prono in Archives de Zool Bepér. 


445; and Professor G. O. Sars! report 1 Zoslogy of the Norwegian North 
B22 











is most abundant, whilst others inhabit the 


| 
iF 
: 


collected by the tow-net. The body of the Cyclops is soft and 


tino it is composed of two distinet parts, a thorax  6ee, a 
seals abelotnes (8 cf which the latter, being a Ke 


= 


is commonly considered as a tail, though tra by the intestine 


which terminates near its 


of ant 
numerous articulations and 
furnished with bristly ap- 
and another small 
pair (d) ; it is also furnished 
witha pair of mandibles or 
true jaws, and with two 
pairs of ‘maxille,’ of which 
the hinder pair is the longer 
and more abundantly su; 
fied with bristles. The 
(e) are all beset with 
plumose tufts, as is also the 
tail (/,,/) which is borne at 
the extremity of the ab- 
domen. On either side of 


egg - capsule (B); within 





which the ova, after be- Fis. 062—A, female of Cyclone quadricwnit: 


ing fertilised, undergo the 
earlier stages of their de- 
velopment. The Cyclops is 
@ very active creature, and 
strikes the water in swimmin, 


i ‘wetan of 
extoruil egg-sncs. C, D, E, F, G, saccessive 
stages of developunont of young. 


not merely with its legs and tail, 


but also with its antenns. The rapidly repeated movements of its 
feet-jaws serve to create a whirl in the surrounding water, by 
which minute animals of various kinds, and even its own young, are 
brought to its mouth to be devoured." 

@ tribe of Branchiopoda is divided also into two groups, of 
which the Cladocera present the nearest approach to the preceding, 


having « bivalve carapace, no 
legs, two pairs of antenne, of 


+ Bee for British forms Professor.G. S. Brady's Monograph the and 
Sie Copepods of the Driteh Tulane pabtabes bythe Ba} Sect, 


1876-80, 


more than from four to six pairs of 
which one is large and brani and 





ful plumose set springing from it’ Ui ‘ itis a 
alaherreor emt ‘imal in this country. The ae 
‘brine-shrimp,’ is an animal of very and almost. 


Sheena the history of the Ento- 
mostraca lie in the peculiar mode in which their ‘ive function 


otherwiso soon be, b repeat eps 
s00n drying up lite! 
of water which constitute their usual habitats 
We do not, of course, imply that the adult animals can bear a eom- 
plete desiccation, alth they will preserve their vitality in ave 
that holds the PACA pom moisture ; but their eges 
there is ample evidence that these will 
become fertile on being moistened, after having remained for a long 
time in the condition of fine dust, Most Entomostraca, too, are 
illed by severe cold, and thus the whole race of adults perishes 
every winter ; but their eggs seem unaffected by the lowest tempera- 
ture, and thus continue the species, elute be otherwise ex- 
terminated. Again, we frequently meet in this ip with that 
agaméic reproduction, which we have seen to 80. extensi 
among the lower forms, In man sracina ilaceidaindon 
odes of multiplication, the sexual and the non-sexual. The 
former takes place at certain seasons only, the males (which are 
often so different in conformation from the females that they would 
not be "jy bee mac pea eiociegn arenes om pee 
in poral congress) disappearing entirely at other times. The latter, 
on the other band, continues at all periods of the year, so long as 
warmth and food are su pplied, and is repented many times so a8 to 
give origin to as many successive ‘broods.’ Further, a single act of 
pregnation may serve to fertilise, not merely the ova which are 
then mature or eae so, but all those subsequently produced a 
the same female, which are deposited at considerable intervals. 
these two modes the multiplication of these little postions 
on with it sopidity, the young animal speedily conning eee 
and mopsants, wa that, according to the computation 
2 he apa data ascertained by actual observation, a 











1 ti ‘ 3 
iow! a aiacuars : ~ 

Tn‘most i at the | 
from the } vein 
only the yet 
sessing but D 
©-G) ; the visual organs, too, faeces 
process of ent, however, with great t 
the animal at Reyer . process is very 
repeated at intervals of a or two) presenting some new parts, 
and Sap ily and ioe its: Pavey hich geese carly 
resem] in its power of m rate | female r 
before she has attained her own full size. ved’ Wand the iaatoeens 
stract have attained their full growth, they continue to exuvinte 
their shell at short intervals the whole of life ; and this 


off and renew their envel ‘The process of 
to depend in some degree upon the influence of . al 
when the animals are secluded from it ; pedal is still more 


regulates the time which elapses between the moul! of 
these, in Daphnia, taking place at intervals of two days in warm 
summer weather, whilst several days intervene between them when 
the weather is colder. The cast shell carries with it the sheaths not 
only of the limbs and plumes, but of the most delicate hairs and 
setse which are attache tothem. If the animal have previously 
sustained the loss of a limb, it is generally renewed at the next moult, 
as in higher Crustacea.! ' 
Closely connected with the entomostracous fren is the tribe of 
suctorial Crostacea,? which for the most part Nee ES 
the exterior of other animals (especially fish), whose juices they 
imbibe by means of the peculiar proboseis-like organ which takes 
in them the place of the jaws of other crustaceans ; whilst other 
ting the foot-jaws, are furnished with hooks, 


Crustacea bear a strong resemblance, even in their adult condition, 

to certain Entotnostraca ; but more commonly it is between the 

earlier forms of the two groups that the resemblance is the closest, 
, 


’ ae and detailed account of Lop ee wee Dr. Baird's Neturat 

Mikory of the Brith’ Entometrac, pubiiahed by Tay Society, "The numenvea 
v1 ally seeeel tint eearinrsbd bo plascGieidh ike Oneal 

now recogn) eee wit ay 

be divided into the Eucopepoda and the Bronchiwras the former are 

Aivisible into the Gnathostomata, most of which are non-parasitic, end have been 

slteady dveibed emer Capepot, abd the Siphonoromata, of which Ler an 


i f to be. 
are followed by 
i the i are chiefly 
imming ; and the tail, also, is a kind of swimmeret, 
Francais eg vase aie reno 
water, usually in a straight line, 


‘kable departure from 
form of the class is shown in the Lernea, which is found h 
to the gills of fishes. This creature has a long sustoeeel obeaas 
a short thorax, to which is attached a single gle pair of h 


at their extremities, where they bear a 
ho parsaite ;.5 large abvomatais, 


hee ee 


ower of changin, 
fon the egg, are as active as the you 
which ey much resemble 5 ne oul 
series of metamorphoses, in whi 

n u Te is curious that 





CIRRIPEDIA 891 


‘© abrupt as it anisht at first sight appear to the group of 
dia, consisting of the pane i their allies ; fort ‘thea, 
my of the Suctoria, are fixed to one spot during the adult 
or their lives, but come into the world in a condition that 
a strong resemblance to the early state of many other 
zea. The departure from the ordinary crustacean type in 
its is, in fact, so great that it is not surprising that zodlo- 
1 general should have ranked them in a distinct class, their 
cial resemblance to the. Mollusca, indeed, having caused most 
atists to place them in that series, until due weight was 
to those structural features which mark their ‘ articulated’ 
ter. We must limit ourselves, in our notice of this group, 
t very remarkable part of their history, the microscopic 





Fio. 663.—Development of Balanus balanvides: A, earliest 
form; B, larva after second moult; C, side view of the same; 
D, stage immediately preceding’ the lous of activity; a, 
stomach (2); 8, nucleus of future attachment (2), 





of which has contributed most essentially to the elucidation 
ir real nature. The observations of Mr. J. V. Thompson ! with 
xtensions and rectifications which they have subsequently 
ed from others (especially Mr. Spence Bate? and Mr. Dar- 
show that there is no essential difference between the early 

of the sessile Cirripeds (Balanide or ‘acorn-shells’) and of the 
culated (Lepadide or ‘ patoacles ”); for both are active little 
ds (fig. 663, A), ee three pairs of legs and a pair of 
vand eyes, and the body covered with an expanded 


ical Researches, No. IV. 1880, and Phil. Trans. 1885, p. 851 
Yn the Development of the Cirripedia’ in Ann. Nat. Hiat. ser. ii. vol. viii. 


BH. 
‘onograph of the Sub-Class Cirripedia, published by the Ray Society. 








MALACOSTRACA 863 


§ the tubular structure of the thick inner layer may be readily 
@strated by means of seetions parallel and perpendicular to 
wface. This structure, which resembles that of dentine, save 
the tubali do not branch, but remain of the same size through 
rehole course, may be particularly well seenin the black extremity 
teclaw, which (apparently from some peculiarity in the mole- 
arrangement of its mineral particles) is much denser than the 
ef the shell, the former having almost the semitransparence 
‘wy, whilst the latter has a chalky opacity. In a transverse 
im of the claw the tubuli may be seen to radiate from the central 
7 towards the surface, so as very strongly to resemble their 
(gement in a tooth ; and the resemblance is still further increased 
'@ presence, at tolerably regular intervals, of minute sinuosities 
sponding with the laminations of the shell, which seem, like 
secondary curvatures’ of the dentinal tubuli, to indicate suc- 
re stages in the calcification of the animal basis. In thin 
ms of the areolated layet it may be seen that the apparent 
‘of the areole are merely translucent spaces from which the 
li are absent, their orifices being abundant in the intervening 
x! The tubular layer rises up through the pigmentary layer 
ye crab’s shell in little papillary elevations, which seem to be 
retionary nodules ; and it is from the deficiency of the pig- 
tary layer at these parts that the coloured portion of the shell 
tes its minutely speckled appearance. Many departures from 
type are presented by the different species of decapods ; thus 
he prawns there are large stellate pigment-spots resembling 
of frogs, the colours of which are often in remarkable 
lormity with those of the bottom of the rock-pools fre- 
ted by these creatures ; whilst in the shrimps there is seldom 
distinct trace of the areolated layer, and the calcareous portion 
the skeleton is disposed in the form of concentric rings, which 
Xto be the result of the concretionary aggregation of the calci- 
'g deposit.? 

Itis a very curious circumstance that a strongly marked dif- 
nee exists between crustaceans that are otherwise very closely 
d in regard to the degree of change to which their young are 
tet in their progress towards the adult condition. For, whilst 
common crab, lobster, spiny lobster, prawn, and ‘shrimp 
rgo a regular metamorphosis, the young of the crayfish and 
+ land-crabs come forth from the egg in a form which corre- 
ds in all essential particulars with that of their parents. 
rally speaking, a strong resemblance exists among the young 
the species of deeapods which undergo a inetamorphosis, whether 
are afterwards to belong to the mucruwroux (long-tailed) or to 








The Anthor is now quite satisfied of the correctness of the interpretation put by 
ley (we his article, ‘Tegumentury Organs, in the Cyclop. Anat. anid 
487), and by Professor W. C. Williamson (‘On some Histological 
Shells of Crustacea’ in Quart. Journ, Micros. Sci. vol. viii. 1860, 
‘upon the appearances which he formerly described (Ieport of British Asau- 
mn for 1847, p. 124) ax indicating a cellular structure in this layer. 
Consult Braun, ‘ Ueber die histologischen Vorginge bei der Hiutung von 
sua fluviatilis,” Arbeit. Zool, Inst. Wireduryg, ii. p. 121. 















COLLECTING CRUSTACEA 895 


eting minute Crustacea the ring-net should be used for 
ater ‘ies, and the tow-net forthe marine. In localities 
for the latter the same ‘gathering’ will often contain 
of various species of Entomostraca, accompanied perhaps 
x of higher Crustacea, echinoderm lurve, annelid larve, 
er Afeduse., The water containing these should be put 
glass jar, freely exposed to the light ; and, after a little 
> eye will become so far habituated to the general appear- 
odes of movement of these différent forms of animal life 
e to distinguish them one from the other. In selecting 
m for microscopic examination the dipping-tube will be 
aable. The collector will frequently find Megalopa larve, 
> by the brightness of their two black eye-spots, on the sur- 
ing leaves of Zostera. The study of the metamorphosis 
> prosecuted, however, by obtaining the fertilised eggs. 
arried about by the females, and races the history of of 
sts. For preserving specimens, whether of Entomostraca 
of the higher Crustacea, the Author would recommend 
y a8 the best medium. 


tsand speculations on the Crusiacos willbe found in F, Miller's Facts 
ts for Darwin (London 1869). The recent work of Reichenbach on the 
of the Crayfish is contained in vol. xxix. of the Zeitschr. f. Wiss. Zool. 
xd vol iu, of the Abhandi. Senckenberg. Naturf. Gesele 1686, Be0 

, by W. K. Brooks, On the Development of Lucifer, in Phil. Trans, 








amas, the less to be regretted, since there already exists in 

our language numerous elementary treatises on entomology, wherein 

the general structure of insects is aly explained, and the conforma- 
wit 


ipscerngyampman lage the microscope is adequately 
‘A-considerable number of the smaller insects. ly those 


werk entire as 
powers, care being taken to "pra their 
seetualy fo a y them, which ae peang i pas 
t ve dried in other positions, by softening them by 
them in hot water, or, where this is objectionable, by exposii ee 
to steam. Full directions on this point, i ta ale 
large insects alike, will be found in the various text-books of ento- 
mology. There are some, however, whose translucence allows them 
to be viewed as transparent objects, and these are either to 
be mounted in Canada balsam or in Deane’s medium, glycerin 
jelly, or Farrant’s gum, according to the degree ii which Beha 
opacity of their integument requires the assistance of the balsam to 
facilitate the transmission of light through it, or the softness and 
delicacy of their textures render an aqueous medium more desirable. 
‘Thus, an ordinary flea or bug will beat be mounted in balsam ; but: 
the various parasites of the /ouss kind, with some or other of which 
almost every kind of animal is affected, should be set up in some of 
the ‘media.’ Some of the aquatic larve of the Diptera and Neuro- 
ptera, which are so transparent that their whole internal organisa~ 
tion can be made out without dissection, are very beautiful and 
interesting objects when examined in the living state, especially 
because they allow the circulation of the blood and the action of the 
dorsal vessel to be discerned. Among these there is none prefer- 
able to the larva of the Ephemera marginata (day-fly), which is dis- 
tinguished by the possession of n number of beautiful appendages 
on its body and tail, and is, moreover, an extremely common 
inhabitant of our ponds and streams. This insect passes two or 
even three years in its larval state, and during this time it 
repeatedly throws off its skin; the cast skin, when perfect, is an 
object of extreme beauty, since, as it formed a complete sheath to 
the various appendages of the body and tail, it continues to exhibit 

¥ An excellent introduction to the study of insects will be found in The Structure 
and Life-history of the Cockroach, by Ly C. Miall and A. Denny eas 1886), 

u 





INTEGUMENT 899° 
Tess 


(butterfly 
Sopaies per of wales tpou test tase 
a uy 
wings. i is to the pecullar coloration ofthe scales the various 
he and nie shee oe by which these Paige eae commonly 
jistinguished, les on one pateh example) being 
those of another red, and so on; for the subjacent elias 
remains perfectly transparent and colourless when the scales have 
been brushed off from its surface. Each scale seems to be composed 
let renee ary SPATE perenne 
it. igment, on which, especially in Lepidoptera, their 
ea eer scales, piu coae jially in the beetle tribe, 
have a metallic lustre, and exhibit brii t colours that. with 
the mode in which the light glances from them ; and thin iid 
cence,’ which is specially noteworthy in the scales of the Cureulio 
imperialis (‘diamond beetle’), seems to be a ry effect, 
depending either (like the prismatic hues of a soxp- 
extreme thinness of ‘the membranous lamellw, or (li 
‘ mother-of-pear! ')on a lineation of surface produced by their corru- 
gation. Each scale is furnished at one end with a of handle or 
pedicle ' (figs. 665, 666), by which it is fitted into a minute socket 
attached to the surface of the insect ; and on the wings of Lepido- 
ptera these sockets are go arranged that the scales lie in very regular 
rows, each row overlapping a portion of the next, so as to give to 
their surface, when sufficiently magnified, very much the appearance 
of being tiled like the roof of a house. Such an arrangement is 
to be ‘imbricated.’ The forms of these scales are often very curious, 
and freq uy aes « good deal on the several parts of the wings 
and of the iy of the same individual, being usually more expanded 
on end Serie aod oe pds hair-like san ee es A 
valiar t; scale, whit een sites np desigza~ 
Yon cael is met with among the Pierida, one v, the prinei 
families of the diurnal Lepidoptera, The P rae are not flat, 
but cylindrical or bellows-shaped, and are hi ; they are attached 
Sed Nag ta treat oper wt pres Bem te ere 
i in i in different: ies, ani from ry 
not from the narrower end of the scale ; whilst the free extremity 
usually tapers off and ends in a kind of brush, though sometimes it 
is broad and has its edge fringed with minute filaments, These 
*plumules’), which are peculiar to the males, are found on the upper 
surface of the wings, partly between and partly under the ordinary 
scales, They seem to be represented among the Lyewnide: by the 
“hattledore’ scales to be presently described. 
‘The peculiar markings exhibited by many of the scales very early 
attracted the attention of opticians engaged in the application of 


E 


4 See Mr. Watson's memoi 
Microscopical Journal, ii. 





‘ Pepys of Battlodore Butterflies,’ in Monthly 
_ ame 








SCALES gor 


termed the ‘battledore’ scales, from their resemblance in 
ito that object (fig. 666, a). These scales, which occur in the 
of several genera of the family Lycenide, and present a 
variety of shape,' are marked by narrow longitudinal 
which at intervals seem to expand into rounded or oval 
that give to the scales a dotted appearance (fig. 667) ; at 
part of the scale, however, these dots are wanting. 
ony. describes and figures them as elevated bodies, some- 
resembling dumb-bells or shirt-studs, ranged along the ribs, 
jing out from the general surface.? Other good observers, 
, whilst recognising the stud-like bodies described by Dr. 
, regard them as not projecting from the external surface 
scale, but as interposed between its two lamelle ;3 and this 
‘seems to the Author to be more conformable than Dr. Anthony’s 
probability. 

more difficult ‘test scales’ are furnished by little wingless 
bets ranked together by Latreille in the order Thysanura, but 














Wis. 666.—Scales of Polyommatus Argue ‘Fie. 667.—Battledore scale of 
{azure blue): a, battledore scalo; 4, Polyommatus Argus (azure 
interference atrive. blue). 


ww separated by Sir John Lubbock,‘ on account of important 
ferences in internal structure, into the two groups Collembola and 
me Thysanura. Of the former of these the Lepismidw constitute 
te typical family ; and the scale of the common Lepisma saccha- 
ima, or ‘sugar-louse,’® very early attracted the attention of 


1 Bee Watson, loc. cit. 
‘Markings on the Battledore Scales of some of the Lepidoptera 'in Monthly 
Sercscopical Journal, vol. vii. 1872, pp. 1, 250. 
® See ‘Proceedings of the Microscopical Society,’ op. cit. p. 278. 
‘See his Monograph of the Collembola and Thysanura, published by the Rey 
a 2. 
! This insect may be found in most old houses, frequenting damp, warm cupboards, 
“especially such as contain sweets; it may be readily caught in a small pill-box, 
‘ich have few pin-holes in the lid; and if = drop of chloroform be put 








Aad holes the inmate will soon become insensible, and may be then turned out 
tea a piece of clean paper, and some of its scales transferred to a slip of glass by 
‘mply pressing this gently on its body. 





by . 
pe by which they can leap like fleas, This is 
well developed in the ies now designated Lepi 

collis, which furnishes what are ordinarily known as 
“When full grown and unrubbed,’ says Sir 
John Lubbock, * this species is very beauti- 
ful, and reflects the most gorgeous metallic 
tints.’ Its scales are of different sizes and 
of different degrees of strength of marking 
(fig. 670, A, B), and are therefore by no 
means of uniform value as tests. “The 
general appearance of their surface, under 
@ power not sufficient to resolve their mark- 
ings, is that of watered silk, light and dark 
bands passing across it with wavy irregu- 
larity ; but a well-corrected objective of 
very moderate aperture now suffices to re- 
solve every dark band into a row of dis- 
tinct ‘exclamation marks.’ A certain 
longitudinal continuity may be traced be- 
tween the ‘exclamation marks’ in the 
ordinary test scale ; but this is much more 
apparent in other scales from the same 
species (fig. 671), a8 well as in the 
scales of various allied types, which were 
carefully studied by the late Mr. R. Beck.* 
Th certain other types, indeed, the scales 








have very distinct longitudinal lel 
ribs, sometimes with regularly disposed Fro, 069.—Scale of Machitis 
cross-bars ; these ribs, being contined to one polypoda. 


surface only (that which is in contact with 

the body), are not subject to any such interference with their optical 
continuity as has been shown to occur in Lepivma ; but more or less 
distinct indications of radiating corrugations often present them~- 
selves, The appearance of the interrupted ‘exclamation marks’ 
Mr. J. Beck considers to be due ‘to it lar corrugations of the 
outer surface of the under membrane, to slight undulations on the 
outer surface of the upper membrane, and to structure between the 
superposed membranes.’ It has been recently stated by Mr. Joseph 


! See Mr. Joseph Beck in Sir J. Lubbock's Monograph, Lg? x 

? Trans, Micros, Soc. v.s. vol. x, 1862, ps, Seo also Mr. Josoph Beck, in the 
appendix to Sir Jolu Lnbbock's Monograph, sndin Month Microsevpical Journal, 
ive. 358. 








HAIRS 905 


dh of the hair of Polyxenus lagurus, of the family Poly- 
(order Chilognatha) is given in fg. 6 of the frontispiece. 
ne of the finest test objects for medium powers, er 
orms of this class are most beautiful objects under the 
microscope on account of the remarkable structure and 
rrangement of their hairs, 
amining the integument of insects and its ap, 
he surface may be viewed either by reflected or transmitted 
ording to their degree of transparence and the nature of 
ering. The beetle and butterfly tribes furnish the greater 
£ the specimens suitable to be viewed as opaque objects ; 
ng is easier than to mount portions of the elytra of the former 
he most showy parts of their bodies), 
wingsof the latter, in the manner de- a 
. Chapter VIL. pp. 388-390. The tribe 
lionide, in which the surface is beset 
os having the most varied and lustrous 
istinguished among Coleoptera for the 
* of the objects it affords, the most 
ile in this respect being the well-known 
imperial: zs cede beetle’ of South 
rts of whose el ») when 1. 
rand looked at with low pore, 
» clusters of jewels flashing against a 
vet ground. In many of the British 
nide, which are smaller and far 
iant, the scales lie at the bottom of 
wressions of the surface ; and if the 
f the diamond beetle be carefully 
|, it will be found that each of the 
of scales which are arranged upon it 
seems to rise out of a deep pit which 
sy itsside. The transition from scales 
is extremely well seen by comparing 
ent parts of the surface of the diamond. 
th each other. The beauty and bril- io, g72.—A, hair of 
many objects of this kind are increased Myriopod: ‘B, hair of 
ting them in cells in Canada balsam, Dermestes. 
igh they are to bo viewed with reflected 
her objects, however, are rendered less attractive by this 
t; and in order to ascertain whether it is likely to improve 
teriorate the specimen, it is a good plan first to test some 
tion of the borly having scales of the same kind by touching 
arpentine, and then to mount the part selected as an object, 
balsam or dry, according as the turpentine increases or 
28 the brilliancy of the scales on the spot to which it was 
Portions of the wings of Lepidoptera are best mounted as 
Ujects without any other preparation than gumming them 
\ to the dise of the wooden slide, care being taken to avoid 
g the arrangement of the scales and to keep the objects, 
unted, as secluded as possible from dust. In selecting such 














907 


squares ; each facet is the ‘corneule' of ocellite, 
ree a St ie ite own pears by Pte prec 


A 


can ascertain number 

in each ‘ eye.’ In the two 
eyes of the common o there are 
as many ax 4,000; in of the 


eabbage-but there are about: 
17,000 ; in the fly, 24,000 ; 
and in the Mordella bettle 25,000, 


‘The structure of the eye 
is best explained by a comparative 
account of the various stages of 
complication which it presents. 
Tn various larve the cuticular 
Jayer is modified to form a single 
lens, behind which are simple, are: 
rate, elongated hyj cells, 
some of which are continuous with 
tine branches of the optic nerve ; 
these may be called retinal cells, 
The next stage in complication is 
seen when these last combine to form 
groups, ‘retinule’; the sensitive 
cells may become divided into two 
regions, an outer one, which is 
‘vitreous’ and refractive in function, 
while the inner part remains sensi- 
tive; the corneal surface may be- 
come broken up into a number of 
facets, each of which corresponds to 
one of the ‘ ids’ so formed, 
and within the retinula there may 
be differentiated a rhabdom fig. 
675) formed by the nerve-ro 

After traversing the pyramids 
the mys reach the extremities of 
the fibres of the as nerve, which 
are surrounded, like the Es 
by pigmentary substance. Thus the 
rays which have passed through the 
several ‘corneules’ are prevented 
from mixing with each other ; and 
no mys, save those which pass in 
the axes of the pyramids, can reach 
the fibres of the optic nerve. Hence, 
it is evident that, as no two ocelli 
on the same side (fig, 673) have 
exactly the same axis, no two can 





Fro, 675 —Part of the nd eye 
of Pheyganea; the cotinal cals are 
seen to be united into a retinuls (r) 

which is differentiated into a thal 

dom (i) posteriorly ; co, eryxtalline 
cone; J, facet of ‘eye; 

‘py, Pigment. (After Grunacher,) 


receive their rays from the same point of an object ; and thus, as 


each 
bined acti 


und eye is immovably fixed upon the head, 
of the entire aggregate will probably only afford but 


the com- 





908 INSECTS AND ARACHNIDA 


a single image, resembling that which we obtain by means 
single eyes. This judgment has received a confirmation as 
pected as it is complete and beautiful. The subject of the 
nature of compound vision can be considered no longer a matter 
doubt, We have as complete evidence of its character as we ha: 
of that of vision by vertebrate eyes. It is to Professor 8. Exner, 
of Vienna, that we are inde! for the striking though simple 
results. He has been engaged’for years on cognate researches, 
and has at length succeeded in taking a photo-micrograph of the 
image presented at the back of a compound insect eye in Piety 
the same manner as a similar beso might be taken wi 
the retina removed at the back of eye of one of the higher 
vertebrates. - 

The demonstration has just reached us as these sheets are Pao 
ing through the press, and the present Editor is indebted a 
knowledge of the following details to the courtesy of a private com- 
munication from Professor Exner, : 

‘The general result of the researches on the subject is presented 
in fig. 6754, which is the image at the back of the compound eye 

of Lampyris splendidula 
(fire-fly) in the ia 
in which it would por- 
trayed upon the retina, but 
magnified 120 dinmeters. 
On to the window pane 4 
letter R cut out in black 
was fixed ; the distance of 
the window from the eye 
was 225 cm. while the dis- 
tance of the church from the 
window through which it is 
seen in the magnified image 
was 135 

‘The result is unmistak- 
able ; theromay appear to be 
some matters of interest still 
needing interpretation, but 
these ma eed in the 
mom it xner, 
ieee ae ae 
method he adopted and the 
mathematical jon of 
the results he obtained, The 
1—Image of a window with the rectitude of the image and 


letter Ron one of its panes, and a charch i 
beyond, taket throagh the compound oye ee Teversion of the are 


rlale 











of Lowpyrie splendidula, and maguiied Certainly noteworthy ; and 
120 diam, as a contribution to aur 
knowledge of the physiology 


portance of the result obtained by the ingenuity 
Exner is great, giving us a new start on 


of sight in insects and other animals with compound eyes, the im 
and skill of Profesor 





=F 


EYES go9 


f the gaestica are fully discussed by Exner ' in a memoir, to 
1e student must be referred for complete information. The 
image formed by the compound eye has long been a matter 
ssion amongst physiologista.? 
process of taking the photo-micrograph copied in fig. 6754 
The eye of the Lampyris was carefully dissected out from 
i, the retina and pigment removed with a fine camel-hair 
ad the back of the eye immersed in a mixture of glycerin 
er, possessing a refractive index of 1-346 ; this was already 
o be the refractive index of the blood of the Lampyris. The 
as placed upon an ordinary cover-glass, and this being fixed 
iges toa alide or object-carrier with a circular aperture cut in 
fig. 6758, C ; a isthe slide with an aperture less in diameter 
e cover-glass 6 cut through it; ¢ is the fluid-medium of 





Fro. 6752.—Diagrammatic illustration of the method by which 
the image in fig. 675a was photo-micrographed. 


6 in which the back parts of the eye are immersed, thus 
g the conditions of living sight, while the cornea with its 
3 shown at d, being, as in the normal state, in air. If the eye 
examined with a microscope (the C of Zeiss was employed) 
wes’ will be distinctly seen, but if the focus be readjusted 


angaber. Akad. Wissench. Wien, Ba. xcviii. (1889), pp.13,143; also Die Phy- 
‘er Facettirten Augen von Krebsen und Insecten (Leipzig und Wien, 1891). 

tical history of the discussion will be found in Chapter VII. of ‘Sir J, 

8 Senses of Animals (London, 1848). The question of the physiology of 
ound eye of Arthropods has given rise to much discussion. For further 
sto its structure consult Grenacher’s great work, Untersuchungen iiber 
rgan der Arthropoden &c. (Gittingen, 1879) ; Currivre, Die Schorgane der 
c. (Munich and Leipzig, 1885) ; Hickson, ‘The Eye and Optic Tract of In- 
fart. Journ. Micros. Sci. xxv. p. 215; Laukenter and Bourne, ‘Tho Minute 
‘of the Lateral und Central Eyes of Scorpio and Limulus,’ Quart. Journ. 
Sei. xxiii, p. 177; Lowne ‘On the Compound Vision and ‘the Morphology 
fin Insects? Trans, Linn. Soc. (2), i p. 38; Patten, “Eyes of Molluscs 
ropods,” Mitth. Zool. Stat. Neapel, vi. 











ara heron Hynes Vente Oaee ae 

fis of all kin Cretan vice Gitte of), Sphi: 

ligustri (privet hawk-moth), ets (silkworm moth and its allies); 
tera, Tabanus (gad-fly), Asilus, 

iy), Musca (house-fly), and 

many others. 


ipper part 

of the head of insects (fig. 
675, bb), present a most 
wonderful variety of confor- 
mation in the several tribes 
of insects, often differi 
considerably in the several 
species of one genus, and 
even in the two sexes of the 
same species. Hence the 
characters which they afford 
are extremely useful in classi- 
fication, especially since their 
structure must almost neces- 
sarily be in some way related 
to the habits and general 
‘economy of the creatures to . 
which they belong, although Fro, 676,—Antenna of Melofontha 
our imperfect acquaintance {cockehater). 
with their function may pre- 
vent us from clearly discerning this relation. Thus among the 
Coleoptera we find one family, including the glow-worm, fire- 
fiy, skip-jnck, &c. distinguished by the toothed or serrated form of 
the antenne, and hence called Serricornes ; in another, of which the 
burying-beetle is the type, the antenna are terminated by a club- 
shaped enlargement, so that these beetles are termed Clavicornes ; 
in another, again, of which the Hyrdrophilue, or large water-beetle, 
is an example, the antenne are never longer, and are commonly 

, than one of the pairs of palpi, whence the name of Paljn- 








or 80 little devel as to be nisable. The 
present the typical conformation of the mandibulate mouth, which is 
aday the ‘ion and division of solid substances ; and. 
consists of the parts : 1,a pair of jaws, termed mandihtes, 


organ which is pi ly the , but which is more 

pane arta ae il any goer Heh 
the tongue being a joctiy whi 

forms the floor of the deta which is uly as a distinct 


= in a comparatively small number of insects, as the cricket. This 


in the fly kind, in which it forms the 


chief part of what is commonly cal the ‘proboscis’ (fig. 678) ;* 


and it also forms the ‘tongue 
+ See the memoir of Dr. 


of the dee and its allies (fig. 679). 


Hicks, ‘On a new Structure in the Antenna of Tnnocts,” 


in Trans. Linn. Soc. xxii p. 147; and_ hin urtber Remarks’ at 1. 96 of the 
See also the momolr of M. Tn 





deseriptions of them, the 
reader is red to Mr. Suffolk's memoir, ‘On the Proboscis of the Blowsfly,’ in 


Monthiy Microsc, Journ. i. p, 881, and 


nd Phyviclogy of the Bitow fi, pad 
pepe A dred Ts 


‘to Mr. Lowne’s treatise on The Bee 
(@ now and elaborate oditinn of this work ix 


Sy 





O14 






INSECTS AND  ARAOHSIDA 


ngae of common fly; , lobes of ligula; b, 


armed by the metamorphosis of the a 


ortion of some of the pewado-trackor more big 





inelosing 








MOUTH-PARTS OF INSECTS . 95> 


\igula of the common fly tz a curious modification of the : 
\aury tracheal structure, of which is not apparent ; - 
tmstead of its trachee being pervious, after the usual 
‘qxn, by the winding of « continuous spiral fibre through their 
“ior, the fibre is broken into rings, and these rings do not sur- 
‘i the whole tube, but are terminated by a set of arches that pass 
& one to another (fig. 678, B).' In.the Diptera, or two-winged 
generally, the labrum, maxille, mandibles, and the internal 
fue (where it exists) are converted into delicate lancet-shaped 
ame Serued regen which, when closed together, are received into 
the upper side of the labium (fig. 678), but which are 
ee make punctures in the skin of animals or 
planta, whence the juices may be drawn forth by the 

a Free itly, however, two or more of these organs may 
os their number is reduced from six to four, three, 


tro. pptera (bee and wasp tribe) the labrum and 


n [ymenoptera 
» mandibles (fg. 679, 6) much 
emble those of mandibulate 


while the ‘ligula’ itself 


Bea te oe amenes muscular 


ee shot annular divi- divi- 
densely covered cere 

own length with lon, 
is tubular, as pra have 
is solid ; when actively 
in taking food it is ex- 
@ great distance beyond Fro. Eo —Parts of the mouth of pis 
















parts of the mouth ; a, mentum; 4, 
Test closel: d Inbial palpi; 
om it is y Nay ‘thane 





and concealed between ly termed Mee touLue 
“The manner,’ says 

‘in which the honey is obtained when the organ is 
it at the bottom of a flower is by © lapping,” or a 


rings aed of th formed by the alt rive sep li 
sen of thie sonze be the alternating series of * ear-like 
ny ith the aie arches,” ie clesing together of which 
into a complete tubo. Dr. Anthony considers each of 
tobe a minute sucker, ‘ether for the edhesion of the eshy 
of fluids, of perhaps purposes.’ point ie 
vestigation. 


a 


palpi 
Bite fretirn out ee eee 
ea eminent), for suction, 
mou' seaections ro tne basen 
three minute ego ees whilst the 
elongated, and are unit 


j 

mutually applied surfaces, and which serves to 

deep cup-shaped flowers, into which the size of their 
these insects from entering. The length of this 
greatly ; thus in such no “ire i 
state it is a very insigni organ ; in some 
fabths, which Hover over’ blouse widlataligh nt 


Fi, 680,—Haustellinm (probeseis) of Vanena, 


inches in dent, ane a butterflies ae it is 
long as the body itself; in Amphonyx, one Sphingide, it is 
or than nine inches long, or about threo times 
body. This haustellium, which, when not in use, ) 
spiral beneath say abd is ia srtenaly Least . 
object, owing to the peculiar arrangement it exhibits 
680), which is probably due to the disposition of ita mus 
n instances the two halves may be seen to be locked tow 

of hooked teeth, which are inserted into little deprossio 


etwoen the teeth of the opposite side, Each half, a ger: 
tained to Se a aoe or sintabs pple 
rvations of Mr. Newport, that sucking .* 
F bP is ( pace oy 





PARTS OF THE BODY ‘917 


tity, with a double row of small projecting barrel-shaped 
1own in fig. 680), which are surmised by Mr. Newport 
inion is confirmed by the kindred inquiries of Dr. Hicks) 
sns of taste. Numerous other modifications of the structure 
outh, existing in the different tribes of insects, are well 
£ the careful’ study of the microscopist ; but as detailed 
ns of most of these will be found in every systematic trea- 
tomology, the foregoing general account of the principal 
t suffice, 
of the Body.—The conformation of the several divisions of 
ntary canal presents such a multitude of diversities, not 
fferent tribes of insects, but in different states of the same 
, that it would be utterly vain to attempt here to give 
mera] idea of it, more especially as it is a subject of far 
est to the ordinary microscopist than to the professed 
. Hence we shall only stop to mention that the ‘muscular 
a which the esophagus very commonly terminates, is often 
everal rows of strong horny teeth for the reduction of the 
th furnish very beautiful objects, especially for the bino- 
iese are particularly developed among the grasshoppers, 
nd locusts, the nature of whose food causes them to require 
nstruments for its reduction.' 
‘reulation of blood may be distinctly watched in many of 
transparent larve, and may sometimes be observed in the 
sect. It is kept up by a ‘dorsal vessel’ (so named from 
m it always occupies along the middle of the back in the 
id abdominal regions), which really consists of a succession 
ar contractile cavities, one for each segment, opening one 
ier from behind forwards, so as to form a continuous trunk 
y valvular partitions. In many larve, however, these 
are very indistinct ; and the walls of the ‘dorsal vessel ’ 
a and transparent that it can with difficulty be made out, 
m of the light by the diaphragm being often necessary. 
which moves through this trunk, and which is distributed 
ve body, is a transparent and nearly colourless fluid, carty- 
it a number of ‘oat-shaped ’ corpuscles, by the motion of 
flow can be followed. The current enters the ‘dorsal 
its posterior extremity, and is propelled forwards by the 
ns of the successive chambers, being prevented from moving 
osite direction by the valves between the chambers, which 
1 forwards. Arrived at the anterior extremity of the 
asel,’ the blood is distributed in three principal channels : 
ane, namely, passing to the head, and a lateral one to either 
mding so as to approach the lower surface of the body. 
a the two lateral currents that the secondary streams 
hich pass into the legs and wings, and then return back 
tin stream ; and it is from these also that in the larva 
hemera marginata (day-fly), the extreme transparence of 


ident who desires to carry further the study of the digestive apparatus 
alt Professor Platesu's memoir, ‘Recherches sur les Phénomtnes de 
-chez les Insectes, Mém. Acad. Roy. de Belgique, xi. 












Ls 
insects which (like the bee) 
feeet powerfal_ Sigh; end 
light, 
Le in ante nial 
ive upon the or 
upon the surface of the 
water. The structure of 
the air-tubes reminds us 
of that of the ‘spiral 
vessels’ of plants, which 
seemed destined (in part 
at least) to perform o 
similar office ; for within 
the membrane that forms 
their outer wall on elastic 
fibre winds round and 
ty Scsaee eentisun of Nepa (waters 
el resombling Fro. 641.—Tracheal system of Nepa 
in. ita porition and func: scomlon); ead; I Art rar of Iga 6 Eek 
tions the spiral wire spring [2nd pair of legos, tracheal trank; gone 
of flexible gus pipes; with- of the st fous Fr asane 
in this, again, however, 
there is another membranous wall to the air-tubes, so that the spire 
winds between their inner and outer coats. When a portion of one 
of the great trunks with some of the principal branches of the 
tracheal system has been dissected out, and so pressed in mounting 
that the sides of the tubes are flattened against each other (as has 
happened in the specimen represented in fig. 682), the spire forms 
two lay which are brought into close apposition, and a 
TiatedEnY appearance, resembling that of watered sill, is 


INSECTS AND ARACHNIDA 
eed 


tho crossing of the two sets of bres, of which one overlies thi 
coe erieeen ee ee 
f of the fibres, which will be found to be perfectly’ 
* stigmata’ or ‘ spiracles’ which the nir enters the 
tracheal system are generally visible on the exterior of the 
‘of the insect 


ity ry 


vee 


i 


ee 
= 


: 


Fin, 052.—Portion of u large trachea of Dytiseus, 
with wong of ite peineipal branches, 


perhaps in scarce] mer, two species are they s 

ing, they are furnished with some kind of sieve at 

which particles of dust, soot, &c. which would otherwi 

air-passages are filtered out; and this sieve may be formed by 
: the inter! t of the 


Not unfrequently the centre of the aper- 
pecetoia oad which radii 

| in the spiracle of 2¥ (crane- 

which breathe air we find one 





RESPIRATORY APPARATUS ‘21 


-of the spiracles of the last segment of the abdomen. nged into a 
tube, the mouth of which remains at the suriace the body is. 
ie 3 the larvae of the gnat tribe may frequently be observed 
in position. 
There are many aquatic however, which have an 
different provision for respiration, being furnished with external k 
like or brash-like appendages into the trachem are su 
that by absorbing air from the water that hathes them may con- 
vey this into the interior of the body. We cannot havea better example 
of this than ial eamiriop ors larva of the common Aphemera (day- 
tly), the body of which is furnished with a set of branchial pert rf 
resembling the ‘tin-fect ‘of bran whilst the three-pronged 
tail also is fringed with clusters of delicate hairs which to 
pees hee sume ee iceres In the larva of the “Lbetlule 
‘dragon-fly) the extension surface for aquatic respiration 
takes place within the termination of the intestine, the lining 
is folded into an immense number of plaits, 
each containing a minutely ramified system of trachew ; the water 
slowly drawn in through the anus 
for bathing this surface is ejected 
with such violence that the body 
is impelled in the opposite dinec- 
tion ; and the air taken up by its 
trachew is carried through the 
system of air-tubes of which they 
form part into the remotest organs, 
This apparatus is a peculiarly in- 
teresting object for the microscope 
on account of the extraordinary 
conan of ae resins of 

trachese in the intes' folds. nai 

The main trunks of the tracheal — 7" + Spire larva of 
system, with their principal ramifi- 
eations, may generally be got out with little difficulty by laying 
open the body of an insect or larva under water in a «dissecting 
trough, and removing the whole visceral mass, taking care to leave 
#8 many a3 possible of the branches, which will be seen pro- 
ceeding to this from the two great longitudinal traches, to whose 
position these branches will serve as a guide. Mr. Quekett recom- 
mends the following ax the most simple method of obtaining a 
perfect system of tracheal tubes from a larva. A small opening 
having been made in its body, this is to be placed in strong acetic 
acid, which will soften or decompose all the viscera ; and the trachen 
may then be well washed with the syringe, and removed from the 
body with the greatest facility, by cutting away the connections of 
the main tubes with the spiracles by means of tine-pointed scissors. 
In order to mount them they should be floated aa slide, on 
which they should then be laid out in the position adapted for 
displaying them. If theyare to be mounted in Canada balsam 

be allowed to dry upon the slide, and should then be 

in the usual way ; but their natural appearance is best preserved 











liar scaly covering of the wings of the Lepidoptera has already 
| tial pei but it may here be added that the entire 

many of the smaller and commoner insocts of this order, 
Tineidee or * clothes-moths,’ form beautiful 

low Pent the most beautiful of ing the divided 
the Fiseipennes or ‘plumed moths,’ especially those of thi 
‘are many insects, however, in which the wings 
less consolidated Ps the interposition of a layer of horny substance 
between the two layers of membrane. This plan of structure ix 
most fully carried out in the Coleoptera (beetles), whose anterior 
wings aré petits into elytra or ‘wing-cases’ ; and it is 
ppeiiiese tail pemeaaree ie ranirer eter rcs 

these insects is distinguished are most strikingly displayed. 

the anterior wings of the Forficulide, or earwig tribe, the cellular 
structure may often be readily distinguished when they are viewed 
by transmitted light, especially after haying being mounted in Canada 
balsam. The anterior of the Or =i 
crickets, &e.), although not By anon tiahal 80 solidified as those of 
Coleoptera, contain a good deal of horny matter ; they are usually 
rendered sufficiently transparent, however, balsam to be 
viewed with transmitted light ; and many of them are so coloured 


f 





absence of any minute structure prevent them from affording much 
interest to the ordinary microscopist. We must not omit to men- 
tion, however, the curious sound-producing aj which is 
by most insects of this order, and Saline ae common, 
-crichet, This consists of the ‘tympanum,’ or drum, which is 
“space on each of the upper wings, scarcely crossed Driving te 
bounded externally by a dark vein provided with or four 
longitudinal ridges ; and of the ‘file’ or ‘ bow,’ which isa transverse 
ridge in front of the tympanum, furnished with numerous 

teeth ; it is believed that the sound is produced by the rubbi 

of the two bows across each other, while its intensity is in 

ee sound-board action of the vip lace ‘The wings of the 
iden Ganterntiy) have much the San texture as those of the 
ptera, and possess about the same value as salexomcna eas 
differing considerably from the purely membranous wings of the 
Cicade and Aphides, which are associated with them in the order 
Homoptera. In the order Hemiptera, to which belong various kinds 
of land and water insects that have a suctorial mouth resembling 
that of the common bug, the wings of the anterior pair are usually 
of parchmenty consistence, though membranous near their tips, and. 








glass. Although, when all 
the hairs have the strain 


and pulvilli, as when we 
remove a piece of adhesive 
plaster by lifting it from Fic, 685.—Foot of fly, 

the orcorner. Flies are 

often found adherent to window-panes in the autumn, their reduced 

strength not being sufficient to enable them to detach their tarsi.! 

A similar apparatus on a far larger scale presents itself on the foot 
of the Dytisous (fig. 686, A). first joints of the tarsus of this 
insect are widely ex ied, 80 45 to form a nearly circular plate, 

and this is provided with a very remarkable apparatus of suckers, 

of which one dise («) is extremely lunge, and is furnished with strong’ 
radiating fibres ; a second (}) is. a smaller one formed on the same’ 
plan (a third, of the like kind, Lean) often present); whilst the 
greater number are comparatively small tubular club-shaped bodies, 

each having a very delicate membranous sucker at its extremity, as 
shown on a larger scale at B, These all have essentially the same 
structure, the large suckers being furnished, like the hairs of the 
fy’ foot, with secreting sacculi, which pour forth fluid through the 


1 Seo Mr. Hepwerth's communications tothe Quart. Journ. Microse. Set. vol. ii. 
184, p. 155, and vol. iti. 1855, p. 812. See wlso Mr, Tuffen West's memair,'On the 
Foot of the Fly, in Trane. Linm. Soe. xxii. p. 398; Mr. Lowne's Anatowy of 
the Biow-Ay, p19; H. Dewite in Zoologischer Ansriger, vie p.478; and G, Simi 
metmacher in Zeitechr, f. Wiss, Zool. x1. p. 481. 








flies, heir allies, the 5' Si, the orpoal Te foralahed 
* saw-flies, in theirallies, ‘iricide, the ovipositor al 
with a still more powerful apparatus for penetration, by means of 
which some of these insects can bore into hard timber, ‘This consists 
of @ pair of ‘saws’ which are not unlike the ‘stings’ of ce hea 
‘but are broader and toothed for a greater | , and are made to 
slide along a firm piece that supports each b) like the ‘back’ of 
a carpenter's ‘tenon-saw’; they ure worked alternately (one being 
protruded while the other is drawn back) with great rapidity ; but 
when not in use they lie in a fissure beneath a sort of arch formed 
by the terminal segment of the body. When a slit has been made 
by the working of the saws they are withdrawn into this sheath ; 
the ovipositor is then protruded from the end of the abdomen (the 
hody of the insect being curved downwards), and, being guided into 
the slit by a pair of small hairy feelers, thére deposits an egg.! 
Many other insects, especiully of the order Diptera, have very pro- 
longed ovipositors, by means of which they can insert their 
‘into the integuments of animals or into other situations in whi 
the larve will obtain appropriate nutriment. A remarkable example 
of this is furnished by the gad-fly (Zinbanue), whose ovipositor is 
1 The above ix the account of the given by Mr. J, W. Gooel, who hee 


informa the Aue that he hag repay voided the stata formes mae by 
ip, 73), that are 
Deiat Br scirr iy secant ot 2 tate hoot WT, toa apie EE 


Réaumur, by manne of # tube tation of the ww 
MeemeLi’ a weparite ripodier procrated muon ihe sama bats basa gttineed 


# 








FiG, 667.—Varions eggs, chiefly of the Aoarina, ate. 


going parts are best geen when mounted in balsam, save in the ease 
of the muscles and poison-apparatus of the sting, which are better pre- 
served in fluid or in glycerin Jelly. 
‘The sexual organs of insects furnish numerous objects of 

interest to the anatomist and physiologist; but as an account of 
them would be unsuitable to the present work, @ reference to = 
copious source of information respecting one of their most curious 
features, and to a list of the species that afforl good il 

must here suffice.’ The eggs of not only the class Judecta, but of 


irs of M. Lacan-Dathiers,' Sarl'Armure Gfmitale dew tn 
i ofe,lii, seek, tomes ik tly. xvil: vil aie] rane ie Tait 











DEVELOPMENT OF INSECTS 93t 


amon with virgin or unimpregnated queens, occasionally lay 
‘om which eggs none but drones are ever produced. From careful 
scopic examination of the drone eggs laid even by impregnated 
8, Siebold drew the conclusion that they have not received the 
sing influence of the male fluid, which is communicated to the 
and worker-eggs alone ; so that the products of sexual 
ation are always female, the males being developed from these 
Procest which is essentially one of gemmation.! 
embryonic development of insects is a study of peculiar 
‘st, from the fact that it may be considered as divided (at 
‘in such as undergo a ‘complete metamorphosis’) into two 
Isthat are separated by the whole active life of the larva—that, 
ty, by which the larva is produced within the egg, and that by 
the imago or perfect insect is produced within the body of 
mpa. Various circumstances combine, however, to render the 
[very difficult one ; so that it is not one to be taken up by 
pusreenced tmicroscopist. The following summary of the 
z the process in the common blow-fly, however, will 
acceptable. A gastrula with two membranous lamelle 
ig been evolved in the first instance, the outer lamella very 
ly shapes itself into the form of the larva, and shows a well- 
€d segmental division. The alimentary canal, in like manner, 
% itself from the inner lamella, at first being straight and 
eapacious, including the whole yolk, but gradually becoming 
rw and tortuous as additional layers of cells are developed 
een the two primitive Jamells, from which the other internal 
ware evolved. When the larva eomes forth from the egg it 
contains the remains of the yolk ; it soon begins, however, to 
voraciously ; and in no long period it grows to many thousand 
1 ite original weight, without making any essential progress in 
opment, but simply accumulating material for future use. An 
aate store of nutriment (analogous to the ‘supplemental yolk’ 
urpura) having thus been laid up within the body of the 
it resumes (so to speak) its embryonic development, its passage 
che pupa state, from which the imago is to come forth, involving 
generation of all the larval tissues; whilst the tissues and 
is of the imago ‘are redeveloped from cells which originate 
the disintegrated parts of the larva, under conditions similar 
2se appertaining to the formation of the embryonic tissues from 
olk.’ The development of the segments of the head and body 
ects generally proceeds from the corresponding larval segments ; 
cording to De Weismann, there is a marked exception in the 
of the Diptera and other insects whose larvw are unfurnished 
legs, their head and thorax being newly formed from ‘imaginal 
? which adhere to the nerves and trachew of the anterior 
mity of the larva ;? and, strange as this assertion may seem, 





tee Professor Siebold’s memoir, On true Parthenogenrsis in Moth and Bees, 

tted by W. 9. Dallas (London, 1857); and his Beitrage zur Parthenugenens 

rthropoden (Leipzig, 1871). 

lee his ‘Entwickelung der Dipteren’ in Zeitschrift f. Wiss. Zool, xiii. and xiv.; 

ywne's Anatomu of the Blow-fly (Ist ed.), pp. &-D, 119-121; und A. Kowalovsky, 
302 




















aires | 933 


‘rane becoming the external covering in the space left. The 
x€ the so-ealled stone-mite (Petrobia lapidum) are discoidal and 
mred ; they occasionally appear in countless numbers over a 
space of ground in a single night, making the place look 
washed ; they have been mistaken for fungi and called Crate- 
pyriforme ; they are good microscopical objects. The larvee 
I Acarina, except Phytoptus and possibly Dermanyssus, are 
rod ; the fourth pair of legs is absent, The nymphal stage is 
ly the principal period of growth ; occasionally, however, it is 
ing. The nymph is an active chrysalis, as in the Orthoptera; it 
ly undergoes several ecdyses. In many species of the Oribatide 
thole skin is not cast, but splits round the edge of the body, 
she dorso-abdominal portion remains attached to the new skin ; 
. it has a row of elegant spines or hairs round its edge; thus 
two or three ecdyses these spines form concentric rings on the 
gaster (Plate XIX, fig. 2). In the Trombidiide, Tyroglyphi, &c. 
aymphs usually greatly resemble the adults ; in the Oribatide 
are often totally different, and every intermediate stage occurs. 
ishange from nymph to adult is usually preceded by an inert 


‘he number and variety of the families, and the differences in 
xternal form and internal anatomy, are so great and so endless 
it is impossible here to do more than indicate a few leading 
res and refer to a few examples of interest. The caput is, of 
, fused with the thorax, but sometimes a constriction at the 
of the rostrum gives a false appearance of there being a distinct 

The trophi are extremely different in the respective families, 
ten genera. In the more highly organised of the Gamaside 
st all the parts which exist in the most elaborate insect-mouths 
xt the labial palpi may be found ; they are well described by 
Mégnin.! A large oral tube is formed by the anchylosed 
Me and probably upper lip and lingua. Up the centre of this 
the mandibles pass freely ; they are very long and chelate : 
irst joint is simply cylindrical ; the second similar, but having 
ixed chela at its distal end; the third is the movable chela. 
‘are capable of being projected far beyond the body, or of being 
drawn wholly within it, the muscles which withdraw them 
1 arising from quite the posterior end of the body. These man- 
+ are different in the two sexes, and those of the male often 
1 most remarkable appendages. One of the best examples is 
of Gamasus terribilis, a species found in moles’ nests by Mr. 
aael. Professor Canestrini, of Padua, also has figured some very 
ular forms. In the Oribatide, Tetranychus, the Sarcoptide, 
the mandibles are also chelate, but of two joints only, shorter, 
e powerful, and not capable of such great protrusion. In the 
hachnide, Trombidiine, &c. the mandible is not chelate, but 
terminal joint shuts back like a clasp-knife, as in the poison- 
of spiders, Other forms of mandible are found. The maxille 
‘arge toothed crushing organs in the Orihatid ; they are very 


1 Journ. de UAnat. et de la Physiol., Robin, May 1476, 





eu PLATE XK. 








West Newrnas.chromo, 


Acarina. { 





MITES 935 


ts had an auditory function, In the Jxodide a singular drum- 
1 structure in the first leg has been considered by Haller and 
ers to be the hearing organ ; while in the Oribatide that organ 
vears to be located in the pseudo-stigmata, two paired organs at 
side of the cephalo-thorax which were long taken for true stig- 
ta. The Gamaside, Oribatide, Tyroglyphide, Sarcoptide, &e. 
‘entirely without special organs of vision. The Hydrachnide 
ve two pairs of simple eyes, each pair being so close together as 
look like a single eye. The Trombidiide mostly have simple 
ts, the number und position of which vary with the species. 
8 to internal anatomy it should be noted that there is almost 
idless variety. The alimentary canal most commonly consists of a 
8g thin esophagus, provided with distensor muscles on each side, 
das to make it a sucking organ ; it usually passes right through or 
ue under the great ganglion known as the brain ; in some species, 
SDanurus geniculatus, the esophagus is followed by a large pro- 
‘triculus, but this is not usual ; it more commonly leads directly 
4 the ventriculus, which generally is a principal viscus, and in 
‘st families furnished with more or less glandular cecal ap- 
adages, not numerous, but often very large, occasionally larger 
‘the organ itself. A valve in many cases separates the ven- 
talus from the hind-gut, which is commonly divided into what 
yy be called colon and rectum. In the Gamaside a single very 
Be Malpighian vessel on each side of the body enters between 
3 two last-named divisions of the alimentary canal. These vessels 
right along the side of the body, and strong pulsation may be 
min them. In the Oribatide they are absent, their function 
ing apparently performed by supercoxal glands. The Tyro- 

ide, Sarcoptide, Phytoptide, &e. are without special respir- 
ory organs ; the Oribatide and some Uropoda have simple un- 
vauched trachex, much in the same condition as those of Peripatus. 
he other Gamaxide, the Trombidiide, Cheyletide, Ixodide, ke. 
tually have branched trachew, like insects ; air-sacs are occasion- 
Wy found, but not anything like the tracheal lungs or gills (so 

)) of spiders and scorpions. The principal nerve-centre is 
‘ch concentrated, and consists usvally of either a large supra- 
‘ophageal and smaller subcesophageal ganglion, joined by com- 
tissures ; or, more frequently, the whole forms one mass, which is 
ieteed by the wsophagus, which may be pulled out, leaving a neat 
‘and hole ; the nerves, of course, radiate from this mass, but there 
Rot space here to describe their course. A pulsating organ of the 
ture of the dorsal vessel of insects, but much shorter, and with 
¥ one or two pairs of ostia, has been detected in some (Gamaside, 

in Ixodes, first by Kramer and afterwards by Winkler and 
Aus ; it has a median aorta running forward ; it is best seen in 
3 in young specimens still transparent ; it lies at the rear of the 
utriculus, near the dorsal surface. Nothing of the nature of o 
art has yet been discovered in other Acarina. The reproductive 
Jans are, perhaps, most frequently of the ‘ring’ type, well known 
the Arachnida 3 thus in female Oribatic they consist of a central 
ary, with an oviduct springing from near each end, in which the 





PLATE XX. 





Acarina 


ab) MITES Lt 937 


with soft, often velvéty skins, frequently of scarlet and other 
iant colours. The large Zrombidium holosericum is a well-known 
toscopical object. The Tetranychi are usually included in this 
ily ; they are, however, rather doubtful members ; theyare the ‘red- 
lers ’ of our greerhouses, much dreaded by horticulturists. Each 
bis provided! with about four singular hairs with round knobs at 
end. Bryobia is an allied genus found in great numbers on ivy 
in gardens and isa beautiful object. The hexapod larve of several 
ties of Trombidium often attach themselves temporarily to the skin 
timals, including man, and produce intolerable itching. They were 
yposed by the earlier Acarologists to be all one species, and to 
Adult, and to form a distinct family ; they were called Leptus 
umnalis, and are known in England as the ‘harvest-bug,’ and 
France as the rouget. The Bde'lide are also included in this 
ily ; some authors also include the Cheyleti, which, however, seem 
eed a separate family, having many curious characters, including 
dorsal position of the male organs. 

The Hydrachnide, or water-mites, as well as the Trombidiide, 
e the two stigmata in the rostrum; the legs are swimming 
ins, the sexes often very different ; they live in fresh water and 
often parasitic in their immature, but not in the adult stages. 

are mostly soft-bodied and often of brilliant colours. 

e Limnocaride are sometimes treated as a sub-family of the 
trachnide, but are crawling, not swimming creatures, and are 
ad in fresh water; but the Halicaride, which either constitute 
ab-family of, or are closely associated with them, are marine, 

are much found among’ Hydrozoa, on which they probably 


y. 
The parasitic Myvbiide are by some included in the Cheyleticee ; 
differences, however, are very considerable. They are the last 
sheate family. 

The Tyroglyphide are the cheese-mite family ; they are far the 
st destructive of all Acarina, swarming in countless numbers and 
vouring hay, cheese, drugs, growing plants and roots, &e. ; the 
us Glyciphagus contains many singular and interesting forms, as 
platygaster and G, Krameri, found in moles’ nests. It is in this 
lily that the curious hypopial stage exists ; some of the indi- 
tals of some species, instead of following the ordinary life-history, 
changed at one ecdysis into a totally different-looking creature, 
ba highly chitinised cuticle and rudimentary mouth-organs, 
ch can endure draught and other unfavourable circumstances 
ch would kill the ordinary form. They attain the same adult 
yas other individuals. The ypopus is provided with adhesive 
sers whereby it attaches itself temporarily to other creatures, and 
serves for the distribution of the species. 

The Tarsonemide are: minute creatures, some leaf-miners, some 
wsitic on bees cc. 

The Sarcoptide: are divided into two great sub-families, the Sar- 
ine, or itch-mites, of which the well-known Sarcoptes scabici of 
(Plate XX, fig. 4)is the type, and the Analgesine, or bird-parasite 
3; all. have.soft bodies with finely striated cuticles. Sarcoptes 





SPIDERS 939 


of silk carried to her den, she can, by a veritable telegraphy, 
instantly, not only the fact that there is prey upon her 
3 the exact spot in the web of the snare in which that 
‘tangled. In the same way by seizing certain taughtened 
communicating with the main lines of the snare, she can 
n an instant the presence and position of her prey, though 
d the reach of vision. 
nost characteristic and interesting parts in the special 
ion of the apider is the ‘spinning apparatus,’ by means of 
often elaborately 
ad webs are pro- 
These consist of 
ts’ on the ex- 
the body and 
organs lying 
e abdomen ; it is 
hat the silk from 
the elements of 
are produced is 





ese glands there 
pairs which are 
n form, with a 
the opening di- 
the spinnerets ; 
three pairs, of a convoluted appearance, opening on the 
innerets ; and there are three of a sinuous tubular form 
on the hinder and middle spinnerets. Beyond these there 
ctively 200 and 400 smaller glands, which open on the 
idle, and hinder spinnerets. They all terminate in tubes 
lelicacy, through which the silk is drawn at the will of the 
and, while the scaffolding or framework of the web of 
double and hardens rapidly in air (fig. 690, A), those which 
the polygons of 
viding are stud- 4 
gular intervals 
id globules, as 
g. 690, B; and B-@—-—_-—_@—_-___© 


nese viscid glo- 


Fia. 689.— Foot, with comb-like claws, of the 
‘common spider (Epetra), 





t the peculiarly Fro. 690.—Ordinary thread (A) and viscid 
sharacter of the thread (B) of the common spider. 
le. 


sual number of the spinnerets is six. They are little teat- 
2sses crowned with silk tubes, They are movable at the 
® spider, and can be erected or depressed, and one, many, 
he tubes crowning a spinneret may be caused to exude, 
drawn from it or them the silk as the spider determines. 
1 be no doubt that there is a difference in the silk secreted 
mt glands, and its appropriate employment is a part of 
of the spider. 

ertain that the silken threads of a snare are of two kinds ¢ 


949 INSECTS AND’ ARACHNIDA 


(1) that which rapidly hardens 6n ‘contact with the air, and which 

is employed in the construction of the framework of the snare ; and 

(2) a viseid silk with which the entangling meshes by which prey is 

caught are put in. The latter present beantiful objects for popular 

observation, because ‘the thread has strung upon it, as it were, 

innumerable pearl-like globules in which the viscidity remains. 

' These beads are produced after the thread is drawn out by a 
special vibratory action set up in the thread by the spider. 

1 The eggs of spiders are not objects of special optical interest, 

but they afford opportunities for good embryological work, and the 

ibe habits of spiders offer a good scope for industrious study in the field. 











i 


CHAPTER XXII 
VERTEBRATED ANIMALS 


\ow arrived at the highest division of the animal kingdom, 
the bodily fabric attains its greatest development, not only 
upleteness, but also as to size ; and it is in most striking 
with the class we have been last considering. Since not 
entire bodies of vertebrated animals, but, generally speak- 
mallest of their integral parts, are far too large to be viewed 
scopic objects, we can study their structure only by a 
examination of their component elements ; and it seems, 
, to be a most appropriate course to give under this head a 
* the microscopic characters of those primary tissues of 
sir fabric is made up, and which, although they may be 
th more or less distinctness in the lower tribes of animals, 
»ir most complete development in this group.' 
ugh there would at first sight appear but little in common 
the simple bodies of those humble Protozoa which consti- 
owest types of the animal series, and the complex fabric of 
sher vertebrates, yet it appears from recent researches that 
er, ns in the former, the process of ‘ formation ’is essentially 
1 by the instrumentality of protoplasmic substance, univer- 
ised through it in such a manner as to bear a close resem- 
the pseudopodial network of the rhizopod ; whilst the 
oduced by its agency lie, as it were, on the outside of 
ing the same kind of relation to it as the foraminiferal 
3 to the sarcodic substance which fills its cavities and 
tself over its surface. For, as was first pointed out by 


ketch ix intended, not for the professional student, but only for the 
-roscopist who wishes to gain some general.idea of the element: 

wn body and of that of vertebrate animals generally. Those 
deeply into the inquiry are referred to the foll 

te treatises that have appeared in this country: The tr 
fanual of Histology, published by the New Sydenham 8: 
for the Physiological Laboratory, by Drs, Burdon-Sanderson, 
aton, and Klein; the translation of the 4th edition of Professor Frey's 
nd Histo-Chemistry of Man; the ‘General Anatomy’ of the 9th edition 
Inatomy, 1482; and the Atlas of Histology, by Professor Klein and Mr. 
1, 1860-4 (a new edition is now in course of publication). 























’ that have long been ed in the midst of the fibres 
Lert sriptanetes phe Seas that are the equi- 
aladts of the corprsclos ct genninel the 
ingtanee came to constitute cell-wuclei, and that the fibres hold the 
same mt ta thet bres hed estes il ae 
their germinal corpusel transition from the one iz to 
‘otbiaes fowl seen in fibro-carti in which the ra 
cellular substance’ ix often as fil as tendon, The difference 
between the two types, in fact, seems essentially to consist in this, 
that, whilst the segments of ‘ germinal matter’ which form the cell- 
nuclei in cartilage and in other cellular tissues are com 
isolated from each other, each being een surrounded by the 
product of its own elaborating action, those which form the ‘con- 
nective-tissue corpuscles’ are connected together by radiating pro- 
longations that pass between the fibres, so as to form a con- 
tinuous network closely resembling that formed by the pseudo- 

in of the rhizopod. Of this we have a most beautiful example 
in bone; for, whilst ita solid substance may be considered as 
connective tissue solidified by calcareous de it, the ‘lacuna’ and 
‘canaliculi’ which are excavated in it (fig. 692) give lodgment ton 
set of radiating corpuscles closely resembling those just deseribed ; 
and these are centres of ‘ germinal matter,’ which appear to have an 
active share in the formation and subsequent nutrition of the oseous 


{ Gront attention has lately been given by many able observers to the changus 
which take place in the niclows bofore and during ite clewrage. A full account of 
these is contained in the neeity pablinbed Srd edition of Professor Steasaburger's 

W840, See also Dr. Klsin’s * on 

Structure of Coll Noclei "in Quart. Journ. Micros, Sos. n.#. vol. xeill, 1878, p. 315, 
ip. 125, 404; and chap. xliv. of hin Atlas of Histology. The 

fumerveawiaysot Pltaning, in recent volumes ofthe Archies. iky. Anat: Gruber, 
Caray, in 

history of the 








on the Nucleus of Protozoa, in vol. al. of the Zeitschr.7. Wisi. Zook; andl 
La , may be stadied by those who dexiru to enrry farther the 





STRUCTURE OF BONE 


magnifying power, a Yoder Sine oy bone, or # section 
CL neil pabmanstte oni iyi cele 2 numerous 
canals, He after discoverer Hay 





whilst in the flat bones they form an irregular network, Oo sep 
ing « higher magnifying ery es ra perma 
ne seat antral that seen oe baccenall whose orifices present theme 
ares a field of view (fig. 691 Fie dee pee 
tissue (1), usually more onions in its fon, which arrange 

at it in concentric rings, 
stem. These rings are ma out and vated by circle of tte 
dark spots, retiche when closely examined (2), are seen to be minute 
flattened cavities excavated in the solid substance of the bone, from 
the two flat sides of which 
pass forth a number of 
extremely minute tubules, 
one setoxtending inwards, 
or in the direction of the 
cenire of the system of 

rings, and the other out- 
wands, or in the direction 
of its circumference ; and 
hy the inoseulation of the 
tubules (or canaliculi) of 
the different rings with 
each other continuous 
communication is esta- 
blished between the cen- pro, b01-—Minute structure of bene ax sean i 
= Haversian Saerires {eanaverse rmoge set 8 rod ‘merronaling 

e outermost part of the — Haversian 
bony od that surrounds yEeeemeh a file ana aa te th 
it, hich doubtless minis- lamella allel wit the oxt surtnce, 
ters to the nutrition of 
the texture. Blood-yvessels are traceable into the Haversian canals, 
but the ‘canaliculi’ are far too minute to carry blood-corpuseles ; they 
are occupied, however, in the living bone by threads of protoplasinie 
substance, which bring the ents of ‘germinal matter’ contained 
in the lacuna: into communication with the walls of the blood- 
vessels, 

‘The minute cavities or /acunm (sometimes but erroneously termed 
‘bone-corpuscles,' as if they were solid bodies), from which Seti 
liculi proceed (fig. 692), are highly characteristic of the true osseous 
structure, being never deficient in the minutest parts of the bones 
of the higher Vertebrata, although those of tishes are occasionally 
destitute of them. The dark appearance which they present in 

sections of a dried bone is not due to opacity, but is simply an optical 
phos dependent (like the blackness of air-babbles i in aquids) 

the dispersion of the rays by the highly retceeies i substance that 

surrounds them. Thesize and form of the lacunse aiden oaey 








TEETH 947 








Long Diameter Short Diameter 
teus. 1-870 to 1-980 1-885 to 1-1200 
nm. . 1-290 ,, 1-480 1-540" ,, 1-975 
nopoma . 1-450 ;, 1-700 1.1800 ,, 1-2100 
ridosiren . 1-375 |, 1-494 1-980}, 1-200 
odactyle . 1-443 ,, 1-118 1-4000 }, 1-522? 


varing sections of bone it is important to avoid the pene- 
the Canada balsam into the interior of the lacuns and 
since when these are filled by it they become almost 
Hence it is preferable not to employ this cement at all, 
aay be in the first instance, but to rub down the section 
e finger, guarding its surface with a slice of cork or a alip 
urcha, and to give it such a polish that it may be seen to 
even when mounted dry. As the polishing, however, 
1uch time, the benefit which is derived from covering the 
f the specimen with Canada balsam may be obtained 
e injury resulting from the penetration of the balsam into 
r, by adopting the following method. A quantity of 
»portioned to the size of the specimen is to be spread upon 
9, and to be rendered stiffer by boiling, until it becomes 
d when cold; the same is to be done to the thin glass 
xt, the specimen being placed on the balsamed surface of 
nd being overlaid by the balsamed cover, such a degree of 
to be applied as will suffice to liquefy the balsam without 
to flow freely, and the glass cover is then to be quickly 
wn, and the slide to be rapidly cooled, so as to give as 
as possible for the penetration of the liquefied balsam into 
system. The same method may be employed in making 
teeth? The study of the ossein or organic basis of bone 
pursued by macerating a fresh bone in dilute nitro-hydro- 
id, then steeping it for some time in pure water, and 
in shreds from the residual substance, which will be 
onsist of an imperfectly fibrillated material, allied in its 
onstitution to the ‘ white fibrous’ tissue. 
—The intimate structure of the teeth in the several classes 
3 of Vertebrata presents differences which are no leas 
» than those of their external form, arrangement, and suc- 
¢ will obviously be impossible here to do more than sketch 
2 most important of these varieties. The principal part of 
ace of all teeth is made up of a solid tissue that has been 
ely termed dentine. In the shark tribe, as in many other 
general structure of this dentine is extremely analogous to 
me, the tooth being traversed by numerous canals, which 
ious with the Haversian canals of the subjacent bone, and 
‘od-vessels from them (fig. 694), and each of these canals 


fessor J. Quekett’s memoir on this subject in the Trans. Micros. Soc. 
3,and his more ample illustration of it in the Illustrated Catalogue of 
tical Collection in the Museum of the Royal College of Surgeons, 


sefal hints on the mode of making these preparations will be found in 
ourn. Micros. Sci. vol. vii. 1859, p. 258. Se0 
P 





TEETH 949 


than dentine, are frequently found associated with it ; the formor is 
oe: and the Latin patne dt ae so re The enamel 
is composed of long prisms, el resembling those “ prismatic” 
shell-substance foraecly described, but ona far more minute scale, the 
diameter of the prisms not being more in man than yylgath of an 
inch. The length of the prisms corresponds with the thickness of 
the layer of enamel ; and the 
two surfaces of this Inyer pro- 
sent the ends of the prisms, 
the form of which maeally ap- 
proaches the hexagonal. The 
course of the enamel prisms is 
more or less wavy, and they 
are marked by numerous trans- 
verse striw, resembling those 
of the prismatic shell-sub- 
stance, and probably origina. 
ting in the same cause—the 
ence of a seriesof shorter 
prisms to form the lengthened 
prism. In man and in car- Fro, 606—Transverse 
nivorous animals the enamel Myliobates (eagie ray), viewed 
‘covers the crown of the tooth "ve object 
only, with a simple cap or 
superficial layer of tolerably 
uniform thickness (fig. 697, @), 
which follows the surface of 
the dentine in all its inequali- 
ties ; and its component prisms 
ave directed at right angles to 
that surface, their inner ex- 
tremities resting in slight but 
regular depressions on the ex- 
terior of the dentine. In the 
tecth of many herbivorous 
animals, however, the enamel 
forms (with the cementum) a 
series of vertical plates which 
dip down into the substance 
of the dentine, and present Fro, 97.—Vertical section of oman molar 
their pee sbecataly with Ss oe iy agra Be eee = 
at the grinding surface of the Petroses ¢, dents eee 
tooth; and there is in such Suman a palpearitys oseows lesan 
teeth no continuous layer of — at outer part of dentine, 
enamel over the crown, This 
arrangement provides by the unequal wear of these three sub- 
stances (of which the enamel is the hardest, and the cementum the 
softest) for the constant maintenance of a rough surface, adapted to 
triturate the tough vegetable substances on which these animals feed. 
the enamel is not always present, it has been shown by Mr. 
Charles Tomes that the germ from which it is formed always appears 





: 
rE 








GEES Gade “a denen | 
ah Hl La He i 


Hy HEU 


ded to consult Mtr. C, §, Tesnews 
ra ratine (ant edition, erent 


part of ‘Roaaes Odontologivehe 


case that they are usui 
comme 


se 

ood 

24 

ae 

sig 

i i 
id 

BE 





SCALES OF FISHES Ost: 

beneath it, or by peries Meeidens (od thickness of the skin and 
for them near its under surface. This is the case, for 

example, with the common eel, and with the viviparous blenny ; of 


teas Calquay hoor iy’ ouantbastaey aera 
“obliqu the su 
thin membrane that arislones at which is studded wi 
cells ; and a portion of the skin of almost any fish, but of 
such as have scales of the ctenoid kind (that is, furn’ 
posterior extremities with comb-like teeth, fig. 699), wl 
with its scales in situ, is a very beautiful opaque object for the 
powers of the microscope (fig. 698), especially with the binocular 
it. Care must be taken, however, that the light is made 
to glance upon it in the most advan- 
manner, since the brilliance with 
ich it is reflected from the comb-like 
jeetic entirely depends upon the 
a at which it falls upon them. The 
only appearance of structure exhibited by 
oe area ee eee 
amined microscopically, is the presence 
a layer of isolated spheroidal transparent 
bodies, imbedded in a plate of like trans- 
ce; these, from the researches of 
W. ©. Williamson! upon other 
scales, ef ra not to be cells (as they 
might ily be supposed to be}, but con- 
cretions of carbonate of lime. When the 
scale of the eel is examined by polarised 
“ee surface ee a becpese St. 
w's cross ; and if « plate o} nite 
be. placed behind it, and the analysing af Wimupaentetioe’™ 
prism be made to revolve, a remarkable 
play of colours is presented. 

In studying the structure of the more highly developed scales, 
we may take as an illustration that of the carp, in which two oa 
distinct layers can be made out by a vertical section, with a thi 
but incomplete layer interposed between them. The outer layer is 
composed of several concentric lamin: of a structureless trans- 

it substance like that of cartilage; the outermost of these 

ins is the smallest, and the size of the plates increases pro- 
gressively from without inwards, so that their marginsappear on the 
surface asa series of concentric lines ; and their surfaces are thrown 
into ridges and furrows, which commonly have a radiating direction. 
‘The inner layer is composed of numerous laminw of a fibrous 


a 
E 





* Boe bis elaborate memoirs, !On the Microscopic Structure of the Scales and 
Dermal Teeth of some Ganoidand Placoid Fish,’ in Phil. Trans. 1840; and * Investi- 
Bion. into pecans and Development of tho Scalos and Bones of Fishes,’ in 


the 

surface of the scales, which is 

that has been likened to the 

order are for the most part angular 

in regular rows, the posterior 

anterior ones of the next, so as 

armour to the body, The scales 

terises ne a i abate and 

irregular in their shape, and very com: 

contact, but are separately imbedded in 

face under various forms, In the rays 
ned plate of a rounded shape, with 

its centre ; in the sharks (to which tril 
own coast) the scales have more o| 





HAIR 953 


A like structure is found to exist in the ‘spiny rays’ of the dorsal fin, 
-which, also, are parts of the dermal skeleton ; and these rays usually 
have a central cavity filled with medulla, from which the tubuli 
radiate towards the circumference. This structure is very well seen 
in thin sections of the fossil ‘spiny rays,’ which, with the teeth and 
scales, are often the sole relics of the vast multitudes of sharks that 
must have swarmed in the ancient seas, their cartilaginous internal 
skeletons having entirely decayed away. In making sections of bony 
scales, spiny rays, kc, the method must be followed which has been 
-already detailed under the head of bone.' 

The scales of reptiles, the feathers of birds, and the hairs, hoofs, 
nails, claws, and horns (when not bony) of mammals are all epi- 
dermic appendages ; that is, they are produced upon the surface, not 
within the substance of the true skin, and are allied in structure to 
the epidermis, being essentially composed of aggregations of cells 
filled with horny matter and frequently much altered in form. This 
structure may generally be made out in horns, nails, &c. with little 
difficulty by treating thin sections of them with a dilute solution of 
soda, which after a short time causes the cells that had been 
flattened into scales to resume their globular form. The most 
interesting modifications of this structure are presented to us in 
hairs and in feathers ; which forms of clothing are very similar to 
‘each other in their essential nature, and are developed in the same 
manner—viz. by an inci apennAeatra of epidermic cells at the 
bottom of a flask-shaped fo which is formed in the substance 
of the true skin, and which is supplied with abundance of blood 
by a special distribution of vessels to its walls. When a hair is 
pulled out ‘by its root,’ its base exhibits a bulbous enlargement, 
of which the exterior is tolerably firm, whilst its interior is occu- 
pied by a softer substance, which is known as the‘ pulp’; and it 
is to the continual augmentation of this pulp in the deeper part. 
of the follicle, and to its conversion into the peculiar substance of 
the hair when it has been pushed upwards to its narrow neck, that 
the growth of the hairis due. The sameis true of feathers, the stems 
of which are but hairs on a larger scale ; for the ‘quill’ is the part 
contained within the follicle answering to the ‘bulb’ of the hair ; 
and whilst the outer part of this is converted into the peculiarly solid 
horny substance forming the ‘barrel’ of the quill, its interior is 
occupied, during the whole period of the growth of the feather, with 
the soft pulp, only the shrivelled remains of which, however, are 
found within it after the quill has ceased to grow. 

Although the Aairs of different mammals differ greatly in the 
appearances they present, we mey generally distinguish in them 
two elementary parts—viz. a cortical or investing substance, of a 
dense horny texture, and a medullary or pith-like substance, usually 
-of a much softer texture, occupying the interior. The former can 
sometimes be distinctly made out to consist of flattened scales 
arranged in an imbricated manner, as in some of the hairs of the 


1For further information rey the scales of fishes, see the 
‘Hertwig in vol. viii. of the bain Zeitachrift; and vols. ii. sof the 
“Morpholog. Jahrbuch. 


Fito. 700—Hair of 
Peacoat te te tones Sone 
imbricated scales or flattetued cells, 


similar structure ; and its cells, 


beats a ae 


A x a or double line of cells, of 
the ‘substance is made 


on 
. 708y hair of the 
soni of sil: Tse RT ands a aot of 


transparent parts of the cortical sheat 
a tater 2 fioted Maar Thekateatthe i 








A), which are most strongly mar! in Pro. 708.—Transverse section 
fustal hairs ; and these are the indications $f Babs oft peconry, 
of the imbricated arrangement of the 


‘The constituent fibres of the substance, which 

Sede (Gh mny be. copacateh fro eueasatte Syne Lat 

may separat \. 

ty fe nner for en ahr 
acid ; and each of them, when completely isolated from its 

is found to be a long spindle-shaped cell. In the axis of this fibrous 

cylinder there is very commonly a band which is formed of spheroidal 

a B 





Fro, 704—Steuotare of human hair: A, external ausface of the shaft, show- 
ing the transverse strive and jagged boundary caused by the imbrications of 
the cuticular layer; B, longitadinal section of the shaft, showing the 

throne off the cortical substance, and the arrangement of the 

ntary mattor; C, transverse section, showing the distinotion be- 

a the cuticular envelope, the cylinder of cortical nubstance, and the 

medullary centre; D, transverse section, showing deficiency of 
the central cellular substance, 


cells ; but this ‘medullary’ substance is usually deficient in the fine 
hairs scattered over the general surface of the body, and is not 
avers present in those of the head. The hue of the hair is due 
partly to the presence of pigmentary granules, either collected into 
patches or diffused through its substance, but partly also to the 

joe of a multitude of minute air-spaces, which cause it to 





956 VERTEDRATED ANIMALS 


dark by transmitted and white by reflected ligh 
the medullary axis in particular are very 

contain air, giving it the black appearsnce shown 
difference between the blackness of it and that 
sony ba ctondiiyaadetermsined: ty vattendtne: sovebelatied 
latter as already laid down, and by watching the 
penetration of oil of turpentine or other liquids, which 
the appearance of pigment spots, but obliterate all t! 
produced by air-spaces, these returning again as the ha 
mounting hairs as microscopic preparations they shoul 
instance be cleansed of all their fatty matter by m 
ether, and they may then be put up either in weak 
Canada balsam, as may be thought pi ‘ble, the former 
being well adapted to display the characters of the fin 
ree hairs, while the Tatton allow the light to pei 
readily through the coarser and more opaque, Trany 
of hairs are best made by gluing or gumming several t 
then putting them into the microtome ; those of hum 
be easily obtained, however, by shaving « second timo, 
4. part of the surface over which the razor has al 
lightly, and by picking out from the lather, and 
the sections thus taken off." 

‘The stems of feathers exhibit the same kind of struct 
their cortical portion being the horny sheath that ¢ 
shaft, and their medullary portion being the pith-lik 
which that sheath includes. In small feathers this ma 
made very plain by mounting them in Canada balsa 
feathers, however, the texture is sometimes so altered b 
up of the pith (the cells of which are always found to 
by air alone) that the cellular structure cannot be d 
save by boiling thin slices in » dilute solution of po! 
always even then. In small feathers, especially sucl 
downy character, the cellular structure is very distinetl) 
Jateral Lavis, which are sometimes found to be 
files of pear-shaped cells, laid end to end ; but in 
it is usually necessary to increase the transparence ¢ 
especially when these are thick and but little pervii 
either by soaking them in turpentine, mounting then 
balsam, or boiling them in a weak solution of potas. 
which are destined to strike the air with it. force 
flight, we find each barb fringed on either with slen 
filaments or ‘barbules’ ; the barbules of the distal side 
ave furnished on their attached half with curved hooks, 
of the proximal side have thick turned-up edges in | 
reas } as the two sets of barbules that spring from | 
barbs cross each other at an angle, and as each hooke 
one locks into the thickened edge of several barbules | 
the barbs are connected yery firmly, in a mode very ai) 


, 1 On the minute structure of hair, consult Grimm's Atlas der me 
dierischen Haare (Lahr, 1854, ato, with « preface by W, Waldeyer). 


HORNS, HOOFS, CLAWS 957 


faa eee ; and 


ness, may well apply himself to the 
structure whieh imparts to these chose their most remarkable 
character.! 


Sections of Aorns, hooft, claws, and other like modifications of 
apa stragture, which can be easily made by the microtome, 
substance to be cut having been softened, if necessary, by soaking 
in warm water—do not in afford any very interesting 
features when viewed in the ordinary mode ; but brag pata eta ie 
on which polarised light produces more remarkable effects, or w! 
display « more beautiful variety of colours when a plate of selenite is 
placed behind them and the analysing prism is made to rotate, A. 
aoe vaeprases . the 
ordi structure orn is 
pencil in the appendage 
by the rhinoceros upon 
its snout, which in many 
ts resembles a bundle of 
ii its substance being 
arranged in minute cylinders 
around a nuinber of separate 
centres, which have probabl; 
by inde 
ent papille (fig. 705). When 
transverse sections of these 
cents are viewed by polar- 
ised light, each of them is 
seen to be marked by a cross, py, 703,—Trunstarse section of hor of 
somewhat resembling that of thinoceros viewed by polarised light, 
starch-grains ; and the light 
and shadow of this cross are replaced by contrasted colours when 
the selenite plate is interposed. The substance commonly but erro~ 
neously termed whalebone, which is formed from the Ree: of the 
membrane that lines the mouth of the whale, aud has no relation 
to its true bony skeleton, is almost identical in structure with 
rhinoceros-horn, and is similarly affected by ised light, The 
central portion of each of its component th like the medullary 





+ Seo R. 8. Wray, ‘On the Structure of the Barbe, Barbulos, and Barbicels of « 
typical Pennaceous Foather,' in the Ibis for 1887, p. 420. 





Sypidd (gb22 58! al 
4 is. ead a 


a2 < ag 


ze i 
Raa 


sis lt i 


Hq 
a 
ain 
E? 
é 


and at b, a8 they 
the foons. 
‘ventral spot 





BLOOD-CORPUSCLES 959 
to shrink and become more opaque, whilst rendering the remaining 
portion extremely transparent (fig. 706, d). By examining un- 
altered red corpuscles of the frog or newt under a sufficiently high 
magnifying power the nucleus is seen to be traversed by a network 
of filaments, which extends from it throughout the ground sub- 
stance of the corpuscle, constituting an intracellular reticulation. 
The red corpuscles of the blood of mammals, however, possess no 
distinguishable nucleus, the dark spot which is seen in their centre 
(fg. 707, 6) being merely an effect of refraction, consequent upon 
the double concave form of the disc. When these corpuscles are 
treated with water, so that their form becomes first flat and then 
double convex, the dark spot disappears ; whilst, on the other hand, 
it is made more evident when the concavity is increased by the 
partial shrinkage of the corpuscles, which may be brought about 
by treating them with fluids of greater density than their own sub- 
stance. When floating in a sufficiently thick stratum of blood 
drawn from the body, and placed under a cover-glass, the red 
corpuscles show a marked tendency to approach one another, adher- 
‘ing by their discoidal surfaces so as to present the aspect of a pile 
of coins ; or, if the stratum be too thin to admit of this, partially 
overlapping, or simply adhering by their edges, which then become 
polygonal instead of circular. The size of the red corpuscles is not 
altogether uniform in the same blood ; thus it variesin that of man 
from about the z7yath to the yyyath of an inch. But we generally find 
that there is an average size, which is pretty constantly maintained 
among the different individuals of the same species ; that of man may 
be stated at about 5,/5yth of an inch. The following table! exhibits 














MAMMALS 
Man . 1-8200 | Camel . 1-8254, 15921 
Dog : 1.3842 | Llama | 1-3361, 1-6294 
Whale | 1.3099 | Javan chevrotain . 1-12325 
Elephant | 1-2745 | Caucasian goat | 1-704 
Mouse 1-3814 | Two-toed sloth | 1.2865 
BIRDS 
Golden eagle . 1-1812, 1-3832 | Ostrich .  . 1-1649, 1-3000 
Owl . —. 1-1830, 1-3400 | Cassowary . 1-1455, 1-2800 
Crow 61, 1-4000 | Heron + 1-1913, 1-8491 
Blue-tit . 313, 1-4128 | Fowl - 1-2102, 1-3466 
Parrot. 98, 1-4000 | Gull . —. 12097, 1-4000 
REPTILES AND BATRACHIA 
Turtle . . 1-1231, 1-1882 | Frog . » 1-1108, 1-1821 
Crocodile _ . 1-1231, 1-2286 | Water-newt . 18014, 1-1246 
Green lizard. 1-1555,1-2743 | Siren. 1-420, 1-760 
Slow-worm . 1-1178, 1-2666 | Proteus . . 1-400, 1-727 
Viper. :1-1274, 1-180 | Amphiuma . 1-345, 1-561 
FISHES 
Perch . . 1-2099,1-2824 | Pike . —. 12000, 1-3555 
Carp. | 1-9142,1-3429 | Eel... 1-1745, 12842 
Gold-fish . 1-177, 1-2824 | Gymnotus . 1-1745, 1-2699 








1 These measurements are chiefly selected from those given by Mr. Gulliver in 


his edition of Hewson's Works, p. 286 et seq. 








of tho single or double nucleus when this comes into 
withdrawal of these corpuscles from the body, In their li 
however, whilst circulating in the vessels, the 


although clearlydistinguishable 

in the slow-moving stratum in - 
contact with their walls (the 

red cor lox ing rapid], 


water, 
which causes them to swell up, 
become granular, and at last 
disintegrate, with emission of 
granules which may have been ‘ 


ly acen in active molo- re, ra9—Alteret white blood 
cular movement within the mc oct aver having aaa ee Re the 


corpuscle. When the white finger. 
corpuscles in a drop of freshly 
drawn blood are carefully watched for a short time, ny may be ob- 
served to undergo changes of form, and even to move from place to 
place, after the manner of Amada. When thus moving they engulf 
peep which lie in their course—such as ales of mecmibon that 
we been injected into the blood-vessels of the living animal—and 
eject these in the like fashion.! Such movements will 


4 Metschnikoff has made the highly interesting und important observation that tho 
Simaonity of certain animals to certain diseases appears to be due to the power that the 
or o 


‘hile corposslos ponsees of acting as eating the germs of the disease, 
Motschuikodl found that the virulent rode of the Bacillus of authrax ‘whan intros 
Gaced by inceclation into an animal Hable to take the faves, euch ap a.todenh were 
Sipser Uy tie Uisod ells only fa exaeplional taxtehoms sty ver once Mbrse 
iy the otc fans thas to the das, tows a ard whe. the 
temperature was not artificially raised a }, ann peared inside we 
colle. - + From all these data wo must assume with Metschallott that the Bacillus 
is harmless because it is absorbed aud destroyed hy the blood-cella, and injuric 
because thle dove not oF at Jeast that it becomes harmlose ifthe 

By the ioocells takes pase ina rapid, and tox yavater extent than tho. growth 
ead eualtiplicaticn of the Bucillus, the converse being also true’ (ane A. da Bary, 
On Bactervo, Engin: edition, p. 156). Tr 








i tean f 
Fro. 711.—Fibrous membrane 
from exe-shell, 


i 
away its lime by dilute acid. The simply fibrous structures of the 
ly generally, however, to one of two very definite kinds of 
tissue, the ‘ white’ and the ‘ sry hac passa stamens 
and properties are very different. The 
fibrous tissue, though sometimes apparently 
composed of distinct fibres, more commonly 
presents the tof bands, usually of a flat- 
tened form, and attaining the breadth of »{yth 
of an inch, which are marked by numerous 
longitudinal streaks, but can seldom be torn up 
into minute fibres of determinate size. The 
fibres and bands are occasio! somewhat 
wavy in their direction ; and they have a pecu- 
Tier tendency to fall into undulations, when it is 
attempted to tear them apart from each other 
fig. 712). This tissue is easily distinguished 
m the other by the effect of acetic acid, 
which swells it up and renders it transparent, 
at the same time bringing into view certain 
oval nuclear particles of ‘germinal matter,’ 
which are known as ‘connective tissue cor- 
puseles.’ These are relatively much langer, and ‘the 
their connections more distinct, in the earlier of ‘germinal matter,” 
stages of the formation of this tissue (fig. 713). WH). eit, stale 
Tt is perfectly inclastic ; and we find itin such — posedamong ikefibros. 
parts as tendons, ordinary ligaments, fibrous 
capsules, &c, whose function it is to resist tension without yielding 
toit. Lt constitutes, also, the organic basis or matrix of bone ; for 
although the substance which is left when a bone has been macerated 
sufficiently long in dilute acid for all its mineral components ole 
Be 











064 YVERTEBRATED ANIMALS 


removed is commonly designated as cartilage, this 

careful mi ic analysis not to be a correct description of 
since it ye a hreag teal the characteristic structure of 
tilage, but is capable of being torn into lamelle, in which, 
ficiently thin, oS ary structure of a fibrous membrane 
ai : 


= 
i 
Fe 


t 

i 

F 
i 
i 
zene 


which ave disposed to curl when not put 

and bis eaeslcremigins ia oe to form a network, are 
the most tween a death 

ac Sariara etoo. suet ah (bate eae 
does not undergo any change when treated with acetic acid. 
exists alone (that is, without any mixture of the white) 
which ‘ire a peculiar elasticity, such as the middle 
arteries, the ‘vocal cords,’ the ‘ligamentum nuchie’ of 


a 
i 

e 
Le 


i: 
Feo 


f 


5 

: 
ef 
es 


7 
E 
F 


z8 
8 ie 
i 





Fro. 714—Yellow fibrous tissue from ligas tive or apeolar tissue, cone 
mT penta uch oft sists of » network of minute 


interwoven in every direction, 80 a5 to leave innumerable ayeole or 
little spaces that communicate freely with one another, Of 
fibres some are of the ‘yellow’ or elastic kind, but the 
composed of the ‘ white’ fibrous tissue ; and, as in that 
mentary structure, they frequently present the condition 
flattened bands or membranous shreds in which no distinet 
arrangemént is visible. The proportion of the two 
according to the amount of elasticity, or of simple resisti 
which the endowments of the part may require. We find 
in a very large proportion of the bodies of higher animals ; 
binds together the ultimate muscular fibres into minute 
unites these fasciculi into larger ones, these again into still 

ones which are obvious to the eye, and these into the entire 4 
whilst it also forms the membranous divisions between distinct 
muscles, In like manner it unites the elements of nerves, 
&e, binds together the fat-cells into minute masses (fig 7: 
into large ones, and so on ; and in this way forms 
part of all the softer organs of the body. “But whilst the flbrons 
structures of which the ‘formed tissue’ is composed have a 
mechanical function, there is good reason to regard the ‘ connective 


i 


i 
5 


Le 
Hi 





H 


i 


i 


especially in the of 
Peenaticnistttiien tienes (ig 713). 
Skin; M and Serous Mem- 


fucous 
branes.—The skin, which forms the ex- 
ternal envelope of the body, is divisible 
into'two principal layers: the cutis vera 
or ‘true skin,’ which usually makes up 
by far the larger part of its thickness, 





ith thelr - 
lines these, which is distinguished ax fatomseltakalla fs g, artnet 
the mucous membrane, from the pecu- — papille p; #, one of the tactile 
liar glairy secretion of mucus by which — P#pilla: with its norve, 
its surface is protected. But those great 
closed cavities of the body which surround the heart, lungs, intes- 
tines, &c, are lined by membranes of a different kind ; which, ax 
they secrete only a thin serous fluid from their surfaces, are known 
ag serovs membranes. Both mucous and serous membranes consist, 
like the skin, of a cellular membranons basis, and of a thin cuticular 
layer, which, as it differs in many points from the epidermis, is dis- 
tinguished as the epithelium. substance of the ‘true skin’ and 
of the ‘mucous’ and ‘serous’ membranes is principally composed of 
the fibrous tissues Inst described ; but the skin and the mucous mem~- 
branes are very copiously supplied with blood-vessels and with glan- 
dulw of various kinds ; and in the skin we also find abundance of 
nerves and lymphatic vessels, as well as, in some parts, of hair- 


trcan the pig. The 


pao Elche frod ef change in the 
edie the Rodtous; o, the tissue, whic 


hair, horn, nails, 
dermic cells we 


pearing to 

able development of A eve in 

is on the inner surface of the choroid 
have a yery regular arrangement, and’ 





EPIDERMIS: 967 


rae ya bas see 7 so Ties Fat dave asin 
nucleus (6) i re thir terion ee sign de tapes 
mulation, wi wae of a pe a of flat ee or oval 
granules, of ex ane cote Ty fe which exhibit an active movement 
AE TES from the cell, and even whilst enclosed within it. 
Sr peaebip not always, however, of this simply rounded or 
form; they sometimes present remarkable stellate pro- 
(Gs. 130,00), ‘The gradual formation of these prolongntions 
ec) ie ui ion 
= Dacweeat Tee P t-cells of the tadpole during its meta- 
morphosis (fig. 717). Similar varieties of 


form are to be met with in the z 
cells of fishes and small crustacea, whi © 0. 


over which the animal may live, so 
serve the better for its concealment. 





iy 

seen. This under-surface of the epidermis 
is not flat but is excavated into pits and 
channels for the reception of Sho peniliny Frio, ree Pe gen ne rails 
elevations of the true skin ; an arrangement oe pos 
which is shown on a large seale in the thick = ie auore complex 
cuticular covering of the dog's foot, the sub- mequently ase 
jacent papille being large enough to be dis- 
tinctly seen (when injected) with the naked 
eye. The cellular nature of the new! Reremrel layers is best seen. 

examining a little of the soft film is found upon the surface 
of the true skin, after the more consistent layers of the cuticle have 
been raised by a blister. The alteration which the cells of the 
external layers have undergone tends to obscure their character ; 
but if any fragment of epidermis be macerated for a little time i bs = 
weak solution of soda or potass, its dry scales become softens 
are filled out by imbibition into rounded or poly, cells. nh 
same mode of treatment enables us to make out the cellular struc- 
ture in warts and corns, which are epidermic growths from the 
surface of papille ealecaae by hypertrophy. 

The eyrthelium may be designated as a delicate cuticle, covering 
all the free internal surfaces of the body, and thus lining all its 
cavities, canals, &c. Save in the mouth and other parts in which 
it approximates to the ordinary cuticle, both in locality and in 








968 VERTEBRATED ANIMALS 


nature, its cells 718) usually form but a single iayer; and 
20 deficient in Sy ne pte aA that they cannot be 
tached in the form of a continuous membrane Their shape varies 
greatly, Sometimes they are broad, flat, and scale-like, and their 
edges approximate closely to each other, 50 as to form 

termed a ‘pavement’ or ‘ tessellated’ epitheliam: such cells are 
observable on the web of a frog's foot or on the tail of pata 
for, though covering an external surface, the soft moist out 

these parts has all the characters of an epithelium. In other cases 
the have more of the form of cylinders, standing erect side 
side, one extremity of each cylinder forming part of the free surface, 
whilst the other rests upon the membrane to which it serves as a 
coveri If the cylinders be closely pressed together, their form is 
oh into prisms; and such epitheliam is often known as 
‘prismatic.’ On the other hand, if the surface on which it rests be 
convex, the bases or lower ends of the cylinders become smaller than 





Fro. 714.—Detached opitholium-celle; x0. 710-—Cilintedl opéttuelitan : 
a, with nuclei 6, and nucheoli ¢, a, ucleated colle rosting on 
from aucows membrane of the their smaller extremitien; }, 
mouth. cilia. 


their free extremities ; and thus each has the form of a truncated 
cone rather than of a cylinder, and such epithelium (of whieh 
that covering the villi of the intestine is a peculiarly a 
ample) is termed ‘conical.’ But between these primary of 
epithelial cells there are several intermediate ions ; and one 
often passes almost insensibly into the other. Any of these forms 
of epithcliam may be furnished with cilia; but these yh ee 
more commonly found attached to the olongated to the 
flattenod forms of epithelial cells (fig. 719). Ciliated epithelium is 
found upon the lining membrane of the nir-passages in alll air- 
breathing Vertebrata ; and it also presents itself in many other 
situations, in which a propulsive power is needed to prevent an ac- 
cumulation of mucous or other secretions. Owing to the very slight 
attachment that usually exists between the epithelium and the 
membranous surface whereon it lies, there is usually no difficulty 
whatever in examining it, nothing more bei than to 
serape the surface of the membrane with a Ienifo and to add o little 
water to what has been thus removed. The ciliary action will 
generally be found to persist for some hours or even days after 
death if the animal has been previously in fall vigour; and the 
cells that bear the cilia, when deta from each other, will 








YAT 969 


swim freely about in water. If tho thin fluid’ that és copional dis. 

Sead be suljsesd to, plot estenties Sie oa mate 
sw mi ii 

be found to contain a great number of ciliated epithelium-cells, 

which have been thrown off from the lining membrane of the nasal 


Fat,—One of the best examples which the bodies of hi; 
animals afford, of a tissue com of an: | 


cells are sometimes di 
Sietiogstne groper al 
sl tl 
shes open a aiacly aptileteal or spheroidal form ; sometimes, 
however, when they are closely pressed together they become some- 
what polyhedral, from the flattening of their 
walls against each other (fig. 720). Their 
intervals are traversed by a minute network 
of eee seseetas( Dy 7041 from which they 
derive their : and it is ene 
by the constant moistening of their 
witha fluid, that their contents are 
retained without the least transudation, 
although these are quite fluid at the tem- 
perature of the living body, Fat-vells, when 
senate theie Loeeameoeer pr it 
peculiar appearance whicl m 
described ag appertaining to oil- % 
globules, being very bright in their centre, 
and very dark towards their margin, in Fro. 720.—Arcolar and qdli- 
consequence of their high refractive power ; pep cies een 
but if, as often happens in preparations that tine. 
have been long mounted, the oily contents 
should have escaped, they then look like any other cells of the same 
form, Although the fatty matter which fills these cells (consisting 
of a solution of stearine or margarine in oie) is liquid at the 
ordinary temperature of the body of a warm-| animal, yet its 
harder portion sometimes crystallises on cooling, the crystals shoot- 
ing from a centre, so as to form a star-shaped cluster. In examining 
the structure of adipose tissue it is desirable, phere peacoat to 
have recourse to some specimen in which the fat-cells lie in single 
layers, and in which they can be observed without disturbing or 
Jaying them open; such a condition is found, for example, in the 
mesentery of the mouse ; and it is also occasionally met with in the 
fat its which present themselves at intervals in the connective 
tissues of the muscles, joints, de, Small collections of fat-cells exist 
in the deeper layers of the true skin, and are brought into view by 
vertical sections of it (fig. 715, f). And the structure of large 
masses of fat may be examined by thin sections, these beng viet 
under water in thin cells, so a8 to take off the pressure of the glass- 
cover from their surface, which would cause the escape of the oil- 














| 


970 VERTEBRATED ANIMALS 
icles, No method of mounting (so fur as the Author is aware) 
Pe easeatal tics exoalag these Neresbectrn te wists 
contents. L 
Oarslage in the ontinery Loris 08 ae eae 
example of a 


tissue obvi composed of colls ; but these are com- 
eee monly separated from each bad 
an‘ which 


i 






ot 
. m= one. jus in the cat of the 
‘Fro, 721.—Collular cartilage of external ear of a bat or mouse (| 
el Ed 721), the cells are packed aa 
ther ag are those of an ordinary 


toget ose 

vegetable parenchyma; and this seems to be the early condition 
of most cartilages that are afterwards to present a different 

Tn the ordinary cartilages, however, cover the ex- 
tremities of the bones, so as to form smooth surfaces for the work~ 
ing of the joints, the amount of intercellular substance is 
considerable ; and the cartilage-cells are commonly found im 
there in clusters of two, three, or four (fig. 722), which are evidently 
formed by a process of ‘ binary subdivision.’ substance of these: 





. 722.—Seotion of the branchial cartilage of any kind, and are nourished 
Fiadpolet 8, ereap of four cell, eparsalag by cbt BIesbe AC aa 
from cach other; b, pair of cells in apposir whole surface, =ilbere atte 
tion; ¢¢, nuclei of cartilage-cells; 1, cavity re 
containing three cells (the fourth probably many cases, however, 
behind). which the structureless inter- 
cellular substance is replaced 
by bundles of fibres, sometimes elastic, but more commonly non- 
elastic ; such combinations, which are termed /ibro-cartilages, are 
interposed in certain joints, wherein tension as well as has. 
to be resisted ; as, for example, between the vertebre of the spinal 
column and the bones of the pelvis, In examining the structare 
of cartilage nothing more is necessary than to make very thin 
sections, preferably with the microtome. These sections may be 


_— 





spheroidal form, which may be as constituting their 


ithelial lining ; these cells, in the of their development, 
eee ath Diecatren Soar the constituents of the 


ticular product they are to secrete ; and they then seem to deliver 
it ee aero tecehinsee Eye melting away of their w 
50 this luct may be poured forth from the mouth of the 
into the cavity in which it is wanted. The organ which is 
though by no means accurately, called the liver presents 
dition in the lowest animals wherein it is found, In many 
compound Tunieata, and Annelida the cells of this organ can 
to occupy follicles in the walls of the stomach ; in insects 
follicles are few in number, but are immensely ak ne 80 a8 to 
form tubes, which lie loosely within the abdominal eavity, frequently 
making many convolutions within it, and disch their contents 
into commencement of the intestinal ; whilst in the 
higher Mollusca, and in Crustacen, the follicles are vastly multi) 
in number, and are connected with the ramifications of gland-ducts, 
like grapes upon the stalks of their bunch, so as to form a distinet 
mass which now becomes known as the liver. The examination of 
the tubes of this organ in the insect, or of 
the follicles of the crab, which may be 
accomplished with the utmost facility. is 
well adapted to give an idea of the 
essential nature of glandular structure. 
Among vertebrated animals the salivary 
glands, the pancreas (sweetbreads ), and 
the mammary, glands are well adapted to 
Eepee the follicuker structure (g.728), Fra. 728—Uliimate {follicles 
‘ing more being necessary in to of mammary 4 with 
make sections of these organs thin e ‘Madpone creiy A on, 
to be viewed as'transparent objects, The nine eve 
kidneys of vertebrated animals are made 
up of elongated tubes, which are straight, and are lined with a 
wement-epithelium in the inner or ‘medullary’ pe of the 
idney, whilst they are convoluted and filled with a spheroidal 
epithehum in the outer or ‘cortical.’ Certain flask-shaped dilata- 
tions of these tubes include curious little knots of blood-vessels, 
which are known as the ‘Malpighian bodies’ of the kidney ; these 
are well displayed in injeoted 1 preparntions. For such a full and 


: 
i AA 








O72 VERTEBRATED ANIMALS 


complete inves! of the structure of these organs: 
perros mnlblogiat sequie, various methods must | 
in practice which this is not! the place to detail, It is. 
nay $0) deena beats! She ool alas nner et Cee ence 
liver by simply jing a ‘ion of its cut surface, since a 
Of ita cla will then be detached. The 

cells in the lobules may be Lah moans of sections 
enough to be transparent ; whilst the arrangement of the 
vi can only be shown by means of injections, 

the tubules of the kidney, sometimes gen bes 
sules in connection with them, muy also be detached by scraping 
cut surface ; but the true relations of these pence 
by thin transparent sections, and by injections of the 

and tubuli. The simple follicles contained in the walls of the 


epee 


ff 


a 


stomach are brought into view by vertical 3 but may 
be still better examined by leaving small ions of the 
membrane for a few days in dilute nitric acid (one part to four 


water), whereby the fibrous tissue will be so softened that 
clusters of glandular M aageusee lining the follicles (which 
very little Altered) will be readily separated. 

‘Muscular Tissue.—Although we are accustomed to speak 
tissue as consisting of ‘fibres,’ yet the ultimate structure 
‘muscular fibre’ is very different from that of the ‘simple 
tissues’ already described, When we examine an 
uiuscle (or piece of ‘ flesh’) with the naked eye, we observe 

is made up of a number of iouli or 
of fibres (tig. 724), which are 
side with great ‘ity, in 
which the muscle is to act, and are 
connective tissue. These fasciculi- 
separated into smaller parts, which 
simple fibres ; but when these are examined by 
the microscope, are found to be themselves. 
fasciculi, com of minuter fibres bound 
together by delicate filaments of connective 
tissue, By carefully these we may 
obtain the ultimate muscular This fibre 
exists under two forms, the striated and the 


i 
aes 








Fre, 724.—Fassioulue non-striated, Tho former is chiefly 
of siriated mussuler by, tho transversely, striated ap; which 
bree idle Sah) it presents (fig. 725), and is due to an 
at J its janetion with alternation of light and dark spaces along its 
the tendon whole extent; the breadth and distance of 


these striw vary, however, in different fibres, 
and even in different parts of the same fibre, according to their 
state of contraction or relaxation. Longitudinal ste are also 
frequently visible, which are due to « partial separation between 
the component fibrille into which the fibre may be broken co 
When a tibre of this kind is more closely examined, it is seen to 
enclosed within a delicate tubular sheath, which is quite distinct on 
the one hand from the connective tissue that binds the fibres into 





MUSCLE © 973 


fasciculi, and equally distinct from the internal substance of the 
fibre. This membranous tube, which is termed the sarcolemma, ix 
not perforated by capillary vessels, which therefore lie outside the 
ultimate elements of the muscular substance ; whether it is pene- 
trated by the ultimate 
fibres of nerves is a point 
not yet certainly ascer- 
tained. The diameter of 
the fibres varies greatly 
in different kinds of verte- 
brated animals. Its ave- 
is iter in reptiles 
and. fishes than in. birds 
and mammals, and its ex- ‘ - 
tremes also are wider ; thus Fi0. 72% —Strinted muscolar flbro, separating 
its dimensions vary in the Inte Sbrilian, 
frog from yhoth to yalsath 
of an inch, and in the skate from th to yigth; whilst in the 
human subject the average is about 4\ th of an inch, and the 
extremes about shgth and »jath, 

The substance of the fibre, when broken up by‘ teasing’ with 
needles, is found to consist of very minute fibrillw, which, when 
examined under a magnifying power of from 250 to 400 diameters, 
are seen to present a slightly form, and to show the same 
alternation of light and dark spaces as when 
the fibrille are united into fibres or into 
small bundles (fig. 7 The dark and light 
spaces are usual, nearly equal length ; 
each light space is divided by a transverse 
line, called * Dobie's line,’ while each dark 
space is crossed by a lighter band, known as 
*Hensen's stripe.’ It has been generally 
supposed that these markings indicate <lif- 
ferences in the composition of the fibre ; but 
Mr. J. B. Hayeraft has recently revived an 
idea, which originated with Mr. Bowman, 
that they are the optical expressions of its 
shape. The borders of the striated fibre 
Ge truly states) present wavy margins, in- 

licative of a transverse ridging and furrow- 
ing, the whole fibre (or a single fibril) thus 
consisting of a succession of convex bead- 
like projections with intermediate coneave 
depressions. When the ais of the fibreis in 
truefocus Dobie’s line, D(fig. 7254), crosses the 
deepest part of the concavity, while Hensen’s stripe, H, crosses the 
most projecting part of the convexity, and it can be shown, both 
theoretically and experimentally, that this alternation of lights and 
shades will be produced by the passage of light through a similarly 
shaped homogeneous rod of any transparent substance. If, on the 
other hand, the suxface of the fibre be brought into focus, the convex 


















usually between galpath and s;'ysth of an inch ; and these bands are 
coll i, which do not lie parallel with each other, but 
cross and interlace. By macerating a portion of such | z 
stance, however, in dilute nitric acid (about one part of ordinary 
rte ae of water) Sepesiel Sa lopen mye 
bands just mentioned easily separated elongated fusi- 
form cells, not unlike ‘woody fibre” in shape (fig. 726, a a) ; each 


in 

distinguished, for the most the presence of a long 
coped nusiria B teeagth tate clea by oe eee oslaete 
ee all in ehh a ee eee ae 
ts can by no means be clearly seen, are composed of a 

substance often containing small pale granules, and sometimes 
globules of fatty matter. In the coats of the blood-vessels are 
cells having the same general characters, but shorter and 
form; and although some of these approach very closely in 


i 


if 


i 





F10.796.—Stractureot non-strinted 
‘tuscular fibre: A, portion of 
tisiue showing fusiform cells a a, 





with elongated cel #2; Bye 

‘ingle cell isolated and” moro 

highly magnified; C, « similar Fio.727.—Gunglion-cetls and nerve 
treated with acetic acid. ‘fibres from a ganglion of lamprey. 


general appearance to epithelium-cells, yet they seem to have quite 
a Rta atsce, being distinguished by their elongated nuclei, as 
well as by their contractile endowments, 

Nerve-substance.— Wherever a distinct nervous systein can be 
made out, it is found to consist of two very different forms of tissue, 
namely, the cellar, which are the essential components of the 

ionic centres, and the fibrous, of which the connecting trunks 
consist. The typical form of the nerve-cells or ‘ ganglion-globules” 
may be regarded as globular ; but they often present an extension 
into one or more long processes, which give them a ‘caudate’ or 
“ stellate’ aspect. These processes have been traced into continuity, 
in some instances, with the axis-cylinders of nerve-tubes (fig. 727); 
whilst in other cases they scem to inosculate with those of other 
vesicles. The cells, which do not seem to possess a definite cell-wall, 
are, for the most part, composed of a finely granular substance, which 





terminations in the muscles and in the skin '. 
protoplasmic axis-cylinder is continued ce 
often then breaking up into very minute which 


i 
z 
: 
a 
z 
zi 
i 
E 
2 
if 


office the luction of 
; Pose those 
which, possessing nerve- 
fibres, have sensory func- 
tions, are usually destitute 
of Siew The 
i interior 
Seek -scmey peyalla 
(tig. pie bs the te 
is oceupit a 
‘axile body,’ ey Stns 
to be morely a bundle of 
ordinary connective tissue, 
CE eee ee Ie an eet Nediol aden hee ea 
appears to terminate. 10 FD, TH — iJ 
nerve-fibres are more jivieutating to form Naxos, of which the lie 
readily seen, however, in mute fibres pass into the cutaneous papille, co, 
the ‘fungiform' papille of 
the tongue, to each of which several of them proceed ; these bodies, 
which are very transparent, may be well seen by snipping off minute 
portions of the tongue of the frog; or by snipping off the papilla 
themselves from the surface of the living human tongue, which can 
be readily done by a dexterous use of the curved scissors, with no 
more pain than the prick of a pin would give. The transparenco 
of these papillw also is increased by treating them with a weal 
solution of soda. Nerve-fibres have also been found to terminate 
on sensory surfaces in minute ‘end-bulbs’ of spheroidal shape and 
about ,}5th of an inch in diameter, each of them being com 
of a simple outer capsule of connective tissue, filled with clear 
soft matter, in the midst of which the nerve-fibre, after losing its 
dark border, ends in a knob. The ‘ Pacinian corpuscles,’ which are 
best seen in the mesentery of the cat, and are from ;/,th to jth of 
an inch long, seem to be more developed forms of these ‘end-bulbs.” 
For the sake of obtaining a general acquaintance ari the 
R 








CIRCULATION OF BLOOD 979 


number of these is very limited. The web of the frog’s foot is 
haps the most suitable for ordinary purposes, more since 


which should be vores Spe Cs the ee nee 
least appearance an ight being reflec 
sarsonshe tasters tons Tua Gitar thie wanclachil 

into view on the adjustment of the focus (a power of from 75 to 100 
diameters bei ‘hi scat satis ie Eager gioar epee) ided 
that no obstacle to the movement of the blood be produced by 
undue pressure upon the body or leg of the animal. It will not un- 


together stagnant for time ; this seems occasionally due to the 
animal's alarm at its new position, which weakens or ze the 
action of its heart, the movement recommencing again after the 
lapse of a few minutes, although no change Tan ba made in 
any of the external conditions. But if the movement should not 
itself, the tape which passes over the body should be slackened ; 

this ieeeinok dae the desired effect, the calico envel 
must be When everything has once been properly 
ljusted, the animal will often lie for hours without moving, or 
will only give an occasional twitch ; and even this may be avoided 
previously subjecting it to the influence of ether or chloroform, 
‘hich may be renewed from time to time whilst it is under observa- 
tion. The movement of the blood will be distinctly seen by that of 
‘its corpuscles (fig. 730), which course after one another through the 
‘k of capillaries that intervenes between the smallest arteries 
ard the smallest veins ; in those tubes which pass most directly 
from the veins to the arteries the cont aera Ee 

a 


SZ seit 


i 





980 VERTEBRATED ANIMALS 


direction ; but in those which pass across between t 
unfrequontly be seen that the direction of the mor 
from time to time, The vessels with which th 
seen to be connected are almost always weirs, a5 
from the direction of the flow of blood in them fro 
oo towards their trunks (a) ; the arteries, whos 
livisions discharge themselves into the capillary 1 
the most purt restricted to the immediate borders of | 
a power of 200 or 250 diameters is employed, the) 
course greatly reduced ; but the individual vessels 
tents are much more plainly seen: and it may tl 
that whilst the ‘red’ corpuscles flow ata rapii 
centre of each tube, the‘ white’ corpuscles, which | 
discernible, move slowly in the clear stream near its 

‘The circulation may also be displayed in the for 





Fro, 780.—Capillary cireulation in « portion of the web of 
a, trunk of Fwin; b, by ite branches; ¢, ¢, plement 


by. laying the animal (previously chloroformed) on it 
head close to the hole in the cork-plate, and, after se 
in this position, drawing out the tongue with the fo, 
it on the other side of the hole with pins. So, ag 
tion may be examined in the fenge—where it afforc 
singular beauty—or in the mesentery of the living 
open its body and drawing forth either organ, the 
previously been made insensible by chloroform. ‘Th 
frog, when sufficiently young, furnishes a good dit 
circulation in its tail ; and the difficulty of keeping 
the observation may be overcome by gradually mix 
water with that inwhieh it is swimming until it b 
less ; this usually happens when it has been raised toa 
between 100°and 110° Fahr, ; and, notwithstanding 
of the body are thrown into a state of i 
treatment, the heart continues to pulsate, and thi 





gills a Inne 

aquatic box or in a shallow cell, Me Be Nis 

dts Bat sa ita “ae the heart's: 

Zeoives Ake vines or te Shed Up costae Menten tt 
as 

{he on shaow elo 8 Inge juatic box 5 elites 

the extreme transparence of these me cae them well 


cher te ey ave ean cd at nates stage “f sani care ar 
vation can be made with the eee 
zodphyte-trough. The store of Folk which the yolk. 
Ete al aca ana ane 
it in 

from The bell iprhes the little creature on Deg rH Is 


wards. ac the bisod ix’ dieetoated over fl copied deste 
partly that it may draw into itself fresh nutritive material, and 
partly that it may be subjected to the aerating influence of the 
surroundin, tie af Pe 
Mpa neat) moreover, for the lay, under proper 
ace cee not only of the capillary, but of eae: ren nelon f 
and if this be studied | under the binocular microscope, the observer 
not only enjoys the gratification of witnessing a most wonderful 
spectacle, but may also obtain « more accurate notion of the rela- 
Socal eae parts of the circulating system than is other- 
possible.* The tadpole, as every naturalist is aware, is 
meemiially a fish in the early period of its existence, beret 
gills alone, and having its circulating Semone arranged 
ingly ; but.as its limbs are developed, and its tail becomes relatively 
shortened, its lungs are gradual evolved in ‘tion for its 
terrestrial life, and the course of the blood is iderably 
in the tadpole as it comes forth from the egg the gills are 
forming a pair of fringes hanging at the sides of the head (fig, 731, 1 
and at the bases of these, concealed by opercula or gill-flaps resem- 
Wedd fishes, are seen. at the rudiments of the internal Is, 
soon begin to be developed in the stead of the pi 
Bfpesial form of live-box for the observation of living tadpoles *o. contrived 
by PAE 


‘Schultze, is described and figured in the Quart. Journ. Micros. Set 
Miyake vi yp Co 


Bev ‘Vil, 1850, p. 118, 
3 See Mr. Whitney's account of “The Circulation in the Tadpole’ in Tvana, 
Bleroest, vo.= 20%8, 3 el aaa ‘per On the Changos 


‘Changes which 
‘the M the 1. xy, 
OAT Teles Sen of leet ween Be Witcay described the tatecoa! pills od 4 
Yingy, an error which be corrected in the second, 








CIRCULATION IN TADPOLE 


2 


(6) is somewhat later in its di with 
the internal gills are rapid. "1 
of vascular tufts, which originate 
from the roots of the arteries of the ills, as seen at g, 5, is 
shown in 4. It is requisite that the sul to 
vation should not be so far advanced as to lost its early trans- 
parence of skin ; and it is further essential to ‘ing out of the 
course of the abdominal vessels that the creature have been 
kept without food for some days, so that the intestine may 
itself. This starvin; reduces the quantity of red. 
doddtue rendéce she! bled paler ; although it makes the 
smaller branches less obvious, circulation in the 
trunks into more distinct view. ‘ the tadpole on his ‘i 


whic globules bat 
heart (har cece by one pe, ee leaving it by another, The 
heart 731, 3, a) appears to as it between two 
pss abd tel cetonalig tight sce defi y Beomithertenie () 
the main arteries arise. The heart is inclosed within an envelope or 
pericardium (¢), which is, perhaps, the most delicate, and is, certainly, 
the most elegant structure in the creature's i Its extreme 
fineness makes it often elude the eye under single microscope, 
but under the binocular its form is distinctly revealed. Then it is 
seen a8 a canopy or tent, inclosing the heart, but of such extreme 
tenuity that its yolds are really the means by which its existence is 
ised. Passing along the course of the great vessels to the 
right and left of the heart, the eye is arrested glee a os 
(d) of a more complicated structure and dazzling appearance. 
is the internal gill, which in the tad) is a cavity formed of most 
delicate transparent tissue, traver by certain arteries, and lined 
by « crimson network of blood-vessels, the interlacing of which, with 
their rapid currents and dancing globules, forms one of the most 
benutiful and dazzling exhibitions of vascularity.’ Of the three 
arterial tranks which arise on each side from the truncus arteriosus, 
4, the first, ov cephalic, ¢, is distributed entirely to the head, ranning 
first along the Sit edge of the gill, and giving off a branch, f, to 
the thick fringed lip which surrounds the mouth ; after whieh it 
suddenly curves upwards and backwards, so as to reach the upper 
surface of the beac where it dips between the eye and the brain. 
‘The second main trunk, /, seems to be chiefly distributed to the gill, 
although it freely communicates by a network of vessels both with 
the first or cephalic and with the third or abdominal trunk. The 
lntter also enters the gill and gives off branches ; but it continues 
its course as a large trunk, bending downwards and pusher! 
the , where it meets its fellow to form the abdominal aorta, t, 
which, after giving off branches to the abdominal viscera, is cons 





INJECTED PREPARATIONS p85 


prein of bet aobees in rapid pony os pera fey 
one 
delicate and ising lesen which lines the shanhonn eaag! 
‘The position of lungs in relation to the heart and the great 
ete is shown in fig. 731, 6. 


art of making successful pre- 
parations of this kind is one 
in which perfection can usually 
be attained only by long prac- 
tice and by ae toa 
great number of minute par- 
ticulars ; and better ea 





may be obtained, Fro. ‘section of 
from thoen who evo ‘made 180. - Endl wah aioieg ten Pesan 
business to produce them 

than are likely to be red by amateurs for themselves. For 
this reason no account of the process will be here offered, the minute 
details which need to be attended to, in order to attain successful 





Fra, 788.—Section of the too of a mouse: dy a, @, tarsal bones; b, digital i; 
‘6, vascular loops in the papille forming the thiek jo cushion on the 
surface; dl distribution of vessels in the matrix of the elaw. ’ 

results, being readily accessible elsewhere to such as desire to put it 

in practice." 

Many anatomical parts, when well injected and mounted, become 
1 Sen ially the article ‘Injection’ in the Mi vo Di: M, 

Robin's work, Du Mioroscope et des Taections} Prot, Veg ct Bos Melaro 

shop und die mikroskopische Technik; Dr, Bealo's How to Work with the Microw 








A relation may generally be traced between the disposition of 
erlang tbienes on speak, of |e aechastal Lady tbeiaerdige 
relation is ol 50 to a mec! 

eae the vessels not in any way determining se eek 





Fie, 785.—Cay network of 
Fro. acpi 10. 7 fata t 


merely administering to it, like the arrangement of water- or gas- 
pipes in 4 manufactory, Thus, in fig. 754, we see that the 

laries of adipose substance are disposed in a network eater roui 
meshes, 50 a5 to distribute the blood among the fat-cells ; 

fig. 735 we see the meshes aor net ya erat 
the muscular fibres to lie in them, Again, in fig, 736, we ol 

the disposition of the capillaries around the orifices of the 

of a mucous membrane; whilst in fig, 737 we see the 


follicles 
loaped 





Fio. 786—Distribution of eapil- Fro, 787.—Distedbutinn of cgi 
laries in mucous membrane, Inries in akin of Bnger, 


arrangement which exists in the papillary surface of the rey 
which is subservient to the nutrition of the epidermis and to the 
activity of the sensory nerves. 

In'no part of the circulating apparatas, pier! does the 
disposition of the capillaries present more points of interest than it 
does in the respiratory organs. Tn bony fishes the surface 
is formed by an outward extension into fringes of gills, each of which 
consists of an arch with straight lamine hanging down from it, and 


ho Handbook to the Physiological Laboratery; and Rutherfort's ok 
treatises on Practical Histology, 





RESPIRATORY ORGANS 


987 


eee these laminw (fig. pliant hte bbe at 


of leaflets, which is most minutely Cae 
network (as seen at A) being so close cine, 
dots in the figure) cover less than the fai selves, 
ae eee ae 


surface, like those of aoe 
and of the larva of the water- 
newt, the necessity for such a 
mode of renewing the fluid in 
contact with them being super- 
seded by the muscular apparatus 
with which their gill-chamber is 
ena repaic the vespletiny cur 
les the sur- 

face is formed by riety of 
an internal cavity, that of the 
lungs: these organs, however, 
are constructed on a pe very 
different from that which they 
present in higher Vertebrata, 
the extension of surface 
which is effected in the latter 
the minute subdivision of 

ie cavity not being here neces- 
ft: In the frog (for example) 
the cavity of each lung is un- 


divided ; its walls, whieh A€ Fi. 788 —Two branchial 


thin and membranous at the 
lower part, there present a 
simple smooth expanse ; and it 
is only at the u *t, where 
the acteinions 4d ‘the tracheal 


cartilage form a network over 


the interior, that its surface is 
into sacculi whose 

lining is crowded with blood- 
vessels (fig. 799). Tn this 
manner a set of aircells is 
formed in the thickness of the 
upper wall of the lung, which 
communicate with the general 
cavity, and very much increase 
the surface over which the blood 
comes into relation with the air; 
but each air-cell has a capillary 
network of its own, which lies 
on one side against its wall, so 
as only to be exposed to the air 
on its free surface. 
general arrangement prevails ; 





branchial processes of the 
fa prt ot ne of thee po 
5 as Seer con ct Meee pee 


showing the caj 
Betwark of Tamefle. © © 





Fro, 789. ao glupper pert ot 
of frog. 


In the elongated lung of the snake the same 
but the cartilaginous reticulation 


ba its upper part projects much further into the cavity, and incloses 


' 


I 


988 VERTEBRATED ANIMALS: 


in its meshes (which are usually square, or nearly so) several layers 
of air-cells, which communicate, one another, with the 
general cavity. The structure of the lungs of birds presents ax with 
an arrangement of a very different kind, the purpose of which is to 
expose a very large amount of capillary surface to the influence of the 


air, The entire mass of each lung may be considered as subdivided 
into an immense number of ‘ lobules’ reper tos 740, B), each of 
which has ita own bronchial tube (or subdivision of the windpipe) 


and its own system of blood-vessels, which have very little com- 





Fio, 140.—Interior structure of Sung of fowl, aa displayed by a soctlon, 
acing 'the direction af brosohiat Subey nY > tmblbae esceser ai 
evtting it across. 





HONS, 


Fro, 741 —Arrangement of the eapillaries on the walls of the nir-cells of 
the human lung. 
munication with those of other lobules. Each lobule has a central 
cavity, which closely resembles that of a frog's lung in miniature, 
having its walls strengthened by a network of cartilage derived from 
the bronchial tube, A, in the inters of which are openings lead- 
ing to sacculi in their substance. But each of these cavities is sur- 
rounded by a solid plexus of blood-vessels, which does not seem to be 
covered by any limiting membrane, but which admits air from the 
central cavity freely between its meshes ; and thus its capillaries are 
in immediate relation with air on all sides—a provision that is ob- 


LUNGS 989 


yasly very favourable to the complete and rapid aération of the blood 
sy contain.’ In the lung of man and mammals, again, the plan of 
sucture differs from the foregoing, though the general effect of it is 
esame. For its whole interior is divided up into minute air-cells, 
1ich freely communicate with each other, and with the ultimate 
mifications of the air-tubes into which the trachea subdivides ; and 
e network of blood-vessels (fig. 741) is so disposed in the partitions 
tween these cavities that the blood is exposed to the air on both 
des. It has been calculated that the number of these air-cells 
touped around the termination of each air-tube in man is not less 
aan eighteen thousand, and that the total number in the entire 
ang is six hundred millions. 

' On the respiratory organs of birds, see Campans, La Respiration des Oiseauz, 
?aris, 1875. 





MICROSCOPIC SECTIONS OF ROCKS 99) 


soil of scientific Germany led to the growth of a ‘micro. 
Tts development we owe to such Continental workers as 
Vi usch, Renard, 


or = 
«to examine minerals and rocks, sections must be pre- 
pared thin enough to permit of the use of transmitted light ; 
this purpose they should be from about y}jth to yylygth of an inch 
A chip about an inch square is struck or cut off the specimen to 
be studied. One surface of this is then ground down on a flat cast- 
‘iron plate wi Wap dake This grinding may be done either by 
tent pe Pesan amnchine specially constructed for this 
App. 424, 425).! The former method will be described here. 
asmooth is at last obtained the specimen is well washed with 
water and then polished aslnb of plate glass with the finest 
flour emery and water. Sieh ities are thus removed the 
it is again well cleansed from all adhering emery. 
next process is to cement it with Canada balsam uponaslab 
-of glass about two inches and about an eighth of an inch in 
thickness. The Canada is first heated over a spirit lamp in 
an iron spoon, care being taken not to allow it to burn. This is the 
most difficult, of the whole process, and only experience ean teach 
‘how long the m must be heated in order to possess, on cooling, 
Socing. "a ight pont appears totbotat ia wih large sie ables 
ing. right point ay to tin wi 
heme th th balsam is poured the slab of 
tit ie Warm upon 
lass and the aad surface of the rock-fragment, Baie reward fake 


= 


Ly 


have nee included bekyeee he tae and the oa Should dha be 
present in any quantity the whole process must be repeated, 

the balsam a4 ite: bartlened Ales other side of the fragment ix 
ground down with coarse emery and water on the iron plate. Upon 
‘the section commencing to become transparent, the grinding with the 
coarse emery must cease. The stone is then thoroughly 

with water, and the final grinding is conducted upon the plate-glass 
slab with flour emery and water, 

The slide is then placed under a stream of water in order to 
remove all traces of the emery powder from the minute pores of the 
vock. This is now the time to employ chemical tests to the com- 
ponent minerals, if such a course be deemed advisable. If the rock 
is of a fragile nature, it is well to mount the section as it is; but in 
most cases it is possible by delicate manipulation to remove it to an 
object-glass more suited to optical work. This is 
sfiected by the application of a gentle heat to the slab until the 
‘balsam becomes Itquefied, when the section can be pushed with a 
piece of wire on toa slide of fine material, Obviously a drop of balsam 
should be poured upon the latter before the section is transferred, 

} Mr. F. G. Cuttell (52 New Compton Streot, Soho) prupares good sections 
‘Mouars, Voigt and Hochgesang (Gilttingen, Rotbo Str, t (Berlin, 8,W, 
Tie dlie eee oe) ane at elt eI 





ena | 
992 THE MICROSCOPE IN GEOLOGICAL INVESTIGATION 


‘Tho slide is then warmed until the balsam becomes liquid, when the 
metas quantity is drawn over the u hp section, 


cleanged with turpentine or aleohol and ether. 2 

Very porous rocks must first be heated with Canada balsam, in 
order to give them the consistency necessary for the preparation of 
thin sections. Isolated mineral grains and can be mounted 
by means of Canada balsam dissolved in chloroform. ‘The slide 
must not be heated, but evaporation allowed to take place. Another 
method is described by Thoulet;! whilst very soft or decomposed 
rocks should be mounted according to Wichmann’s a 

In the application of the microscope to and minera- 
logical research the employment of polarised light is constantly re- 
bree and ete means oi appliances ia, ga ‘most 

vantageous application, which are not ii e 
microscopist, "Gansiderable pains have ha bestowed seared 
English and Continental makers to fulfil the requirements, and good 
instruments are now plentiful.* 

An instrument having been recently brought out by Messrs. J. 

Swift and Son, which combines all that ience has led petrologists: 
to consider desirable for mineralogical and petrological in’ 
a brief account of it is here subjoined. Tt 18 specially adapted tothe 
study of the optical propertios of minerals generally, and particularly 
to that of the thin plates of minerals seen in ordinary sections of 
rocks prepared for microscopical examination. The microscope is 
shown in fig. 742.* 

The eyepiece tube is slotted at F to receive the micrometer scale 
(shown detached at F), and to the tube is hinged the analyser B’, 
which is capable of independent rotation in the usual manner, 
Upon the eyepiece tube is mounted « toothed wheel, which gears 
into another toothed es ee oa one i of a rod formed of 

inion wire. Below the stage, whic! nei sliding nor rotatory 
SSE is mounted the piers B, capable of independent rota- 
tion like the analyser, and upon the tube of the polariser is mounted 
a toothed wheel of the same size as that upon the analyser; this 
wheel gears into a wheel carried by a tube which forms a 
extension of the pinion wire, the object being to allow of the 
or lowering of the body of the microscope for ing, The ana- 
lyser and the polariser may thus be rotated synchronously without 
disconnecting their toothed wheels. Now, in the 
usually constructed for petrological work the rotation of a small 


E 









1 Annates de Chimie et de P . 802482. 
1 Techormak's Minernjogisch Atitt, Ba. v. 1881, p, 88. 
3 Mr. Watson, of Holdorn, Lemilot Linsited, make wnit. 


able instruments. Those constructed by Zeiss, of Jenn; Neches, of Paris; Vs 
Hochgesang, of Gtittingen ; Fooss, of Berlin; and Hartneek, of Potedas, ee 
recommended. 

* The instrament ix protected by lettors patent. 











7 


‘994 THE MICROSCOPE IN GEOLOGICAL INVESTIGATION 


‘be adjusted so a8 to be + for one objective, it is likely to be 
perc asothar eee col is meant a crystal under the 
ydooth of an inch in diameter, and of such thickness as one finds at 
the edges of petrological sections.) Hence, 

wi 


a socnog Bate and fixed cross-wires a familiar 
section looks strange when first looked at on «fixed stage with mov- 
able cross-wires, but after a few hours’ work with the Taaborsece 
the fecling of strangeness passes and that of the solid advantage 


wil ting 

ijusted in the field. Oss eee et eae Err 
apparatus aud goniometer ma: fixed 

oth the analysing and laridg prisms are divided to Liat 2 
spring catch marking the extinction point. The 
the upper lens of the eye-piece and the analysi Rie (6 74) 
is for the purpoad of pliciey aiehijistealailt aati iaiaetnate tate 
in position. 

The great value of the instrument is in the facility with which 
studies in convergent light can be performed. G is a slide fitted 
with a double convex lens which may be used for showing the 
optical figures of crystals, and H is a similar slide carrying a lens 
and diaphragm of small aperture used for showing optical pictures 
in minute crystals. The polariser is fitted with two peasy Bele Jenses, 
which work in conjunction with the lens A on the slide of the 4 
when great convergence is required. This slide may be pushed i 
without disturbing the object upon the stage. The achromatic con- 
denser, A, shown at the foot of the figure, also works in 
with the sliding lens, A, when thehighest angular aperture is required, 
When convergent light is required the slide on the stage and 
either G or Hare pushed in, and the eye-piece covered with the 
analyser B'. The optical figures of the crystal then aj with 
almost ideal clearness, If this simple method is com with that 
previously in use the superiority of the instrument will be im- 
mediately recognised. It is in fact the most perfect i 
microscope yet issued, and is one which will suit equally the minera- 
logical and petrological student, The instrument was desi 
by Mr. Allan Dick and marks a great advance in this ot 
microscopical science. 

The microscopical investigation of rock sections has almost re- 
velutionised petrology. Although the geologist has no in 
determining by his unaided eye with the use of simple chemical tests 
the mineral components of rocks of conrse texture, the cast is 
different with those of extremely fine grain ; still more with such ms 
— an apparently homogeneous, Gores | and glassy character. 

ho study reveals facts of the most striking signiticance, and wel- 





phyriti rocks: le, olivine, 

not ieee show the mide shea TAS the dott 
line marks the original outline). In the of the hornblende 
dissolved portions usually give rise to the forma- 

tion of staal goaina otasigito Red oauuet hey ete 

are then found incircling the ‘ mother-erystal.’ 


sometimes at 
at dias from, pi leroey As the lava ] 
suse dow t of crystals occurs, 
‘The products of this constitute the * ground: HW 


mass’ of the rock and are usually small in size, the 
microscope being frequently requived othe thet Die aise Cmca 
detection and determination. of Kilima Najaro, 
‘Thislast stage of consolidationoften inducesthe Past Afriea. 
formation of glass and gives rise to the row 
of very remarkable products, which are known to be the result of 


detinite chemical” compounds, endeavouring peel under un- 
favourable circumstances. Gisealivoaren ssn, thes lucts are 
present in two stages of patches fi ly derslonad 


forms of these are known as crystallites, The occur in a variety of 
forms—hair-like, spherical, &e.—and represent matter in a state 


+ The reader is refeered to the works treati) Sarak mornireems am 
bei mineralsand rocks:—F. ooo ind ahah 

Paris, 1878; E. Hussak, Anioitung eum Beat tea fonden, 

feel, Bet 1685; E. Kalkowsky, Biemenée om aihod centre i" 

Tasanlx, Elemente der Revere boas Bom nee ce iagra in die Gestetna- 

1880 oe edition in Prench Petes dew 

foches, Pars Paris TBS ; 








1884, and Rock-forming Afin J. 
Ch. Velain, Conférences de Pétrographie, ler fascicule 
Lichrbuch der Petrographie, 2 vols. Bann, 1866; Basalégesteim 7 
fominrg aru Beachatenhelt der Minerulien tani Geateine, Lelprig, 1878; Micro- 
rrography (U.8, Geo}, Exploration of 40th parallel}, 








ey 


de 
996 THE MICROSCOPE IN GEOLOGICAL INVESTIGATION 


intermediate between that of « glass and a erystalline body, hence 
are optically inactive. Tho conditions of their formation have been 
aeseataliy determined by Vi ng. 

The bodies belonging to the highest stage of optren a! 
called microlites (fig. Ty, ‘They differ from the erystallites in possess- 
ing the internal structure of true crystals and in acting on polarised 
Tight. The position of the microlites with reference to each other 
or to the large peter be of the movements: 
of the original fluid mass, When streams of microlites are seon 
lying with their long axes in one direction, this direction is equi- 
valent to that of the flow, and where such streams encounter lnege 
erystals they sweep round therm in graceful curves: this appearance 
in a rock is known as fluxion-structure. 

Masses of molten material may, however, consolidate at a con- 
siderable depth beneath the surface of the earth ; in such cases the 
Atitinetlon between the first and second periods of crystallisation ix. 
not so well marked. 

A crystal is, in one respect, like an organism—it is affeeted by 
its environment, The crystal modifies its surroundings, and is in 


1 u 


Fro, 74. —Microlites. (After Zirkel,) 10. 748,—Augite showing aonal 
structure. (After Zérkel.) 


turn modified by them ; there is action and reaction between it and 
its environment. This remarkable property of all crystalline bodies 
is well shown by the microscope, Crystals are ere found 
built up of different layers or zones of material, unlike in their 
optical characters, and hence dissimilar in chemical constitution. 
his ix the so-called zonal structure, and is common to the 

and augites—in short, to nearly all minerals representing b 

mixtures (fig. 745). In the case of the augites a difference in colour 
often indicates its presence. ‘This structure unquestionably si 








changes in the environment of the crystals during their the 
precipitation of each successive zone affecting the chemical con- 
stitution of the succeeding one. This structure may be i 


mentally produced by placing an artificial in a solution of « 
substance isomorphic with that of the crystal 

Another great service has been rendered by the microscope, 
inasmuch as it has enabled the petrologist to draw conclusions as to 
the physical condition of the fused mass or magne at the time 
crystallisation commenced. All chemists are aware that when 


ma 





pressure ii 
iquid water and mineral matter the will contain 
pe salen and also fluid inclusions. mati 

Glass inclusions are very abundant in the porphyritic 
-of voleanic rocks and represent to some extent the composit of 
wo Set oes anne ag of inclosure. The glass composing the 
inclusions is often darker in colour than the glass forming the base 
of the rock. This is probably due to the presence in the glass of 
the inclusions of a iter amount of iron and the bases usually 
associated with it, glass often contains crystallites and micro- 
lites, sometimes due to inclosure at the pe ake repre arenas 
sul it ising action set 
papper gare 

‘The existence of fluid inclusions in crystals has long been known ; 
but not until Dr. Sorby directed his attention to the subject was 
Conring ups goclogiealprobluse vonogne Thay te tioa rary 

uy al roblems . are 
yorete) being frequently less than pyhgath of an inch in Riana: 
‘They are rare or absent in rocks of the voleanic sou, but are: 
me stir characteristic of the plutonic rocks, such as 

bro, diorite, dc. Whore glass inclusions are common, fluic 

clusions are rare or wanting. 

Sometimes the fluid inclusions are so numerous in the quartzes 
of the granites us to be, according to Dr. Sorby,? ‘not above the 

th of an inch apart, This agrees with the proportion of a 
millions to a cubic inch, and in some cases must be 
more than ten times as many,” 

‘The forms of such inclusions vary, but they may be bounded by 
planes corresponding to the external faces of the crystals, and are 
‘then termed ‘negative’ crystals. 

There is usually an intimate relation between the number of 
cavities in a crystal and the rate at which it was formed. 
Generally speaking, it may be said that the more rapid the growth, 
the more numerous the inclusions. 

Not infrequently the cavities contain bubbles varying from 
tehwnth to ¢yhonth of an inch in size. These bubbles sometimes 
possess an apparently spontaneous movement, at other times heat 
must be applied to produce a change of position. 

jing to Dr. Sorby’s experiments, the bubbles arise in con- 

sequence of the contraction of liquid on cooling from the high 
temperature at which the cavities were filled. 

nature of the inclosed fluid has been determined with some 

accuracy. Generally the liquid is a solution of water charged with 


1 Sorby, Quart. Journ, Geol, Soc, 1868 p. 42 2 Op. cit, pe 486, 





== 


998 THE MICROSCOPE IN GEOLOGICAL INVESTIGATION 


salts ; but it is seldom so concentrated ax to cause the deposition in 
the cavities of little squares of salt. The has also been 
established of liquid carbonic dioxide, the bubble of which dis- 
appeared at about 32° C., the critical point for this gas! 
The discovery in the mineral components of plutonic rocks 
of these fluid inclusions is mani: of the highest im 
Daubreo's experiments bave shown enormous § 
powers possessed by overheated water, whilst the presence of liqui 
carbonic dioxide testifies to the enormous pressure under 
plutonic rocks, such as granite and diorite, have consolidated, 
Tnclusions of gaseous matter are also common ; and it is self- 


i] 


evident that the occurrence of one mineral in another is no ; the 
included mineral is either contemporaneous or older, the 
latter. Tosuch microscopic inclusions of crystalline bodies is due the 


atibbite from the Fassathal in Tyrol. Tn fact, so numerous and so 
minute are the inclusions in some minerals that even with high 

powers the minerals aj to be charged with 
the finest dust. The leucite isa good instance 
of this (Bg. 746). 

‘The foregoing allows us to conclude, that an 
absolutely pure mineral is ional. Alt 
such inineral bodies contain inclosures of foreign 
Fio, 740.—Leucite from ™matter which have become entangled during 

Kilima Nojaro, East their formation ; when they contain glass inelu- 
Africa. sions they have been precipitated Gi a mass 
ib 


in the condition of igneous fusion. solaer 
therefore, that a charneteristic of igneous rocks is the presence 
amorphous glass in their composition, either asa glassy residue or as 
lass-inelusions. Still, the absence of such material does not 
Sasa rate the non-igneous origin of the reek, for, on the other 
hand, plutonic rocks, such as granite, do not possess this feature. 
Their ical occurrence shows them to be eruptive. Glass~ 
inclusions are certainly reported by Sigmund? to be present in the 
quartzes of the granites of the Monte Mulatto, near Predazzo, inSouth 
‘yrol, but V. Chrustschoff considers them products of contact-mete- 
hi 









or m. 
aa have dealt hitherto more especially with igneous masses, but 
the sedimentary rocks demand some attention. 

The microscope enables us to recognise to some extent the sources 
whence the materials composing clastic’ rocks were derived. For 
instance, the presence of quartzes containing numerous fluid inclusions 
(especially those of carbonic dioxide) and hair-like crystals of rutile 
lend us to conclude they are derived from granites or similar rocks. 
‘The cemented material can also be studied and its nature determined. 


4 The application of the burning end of a cigar to the section fs usually sufficient 
to caus the bubble to disappear. 


o Granit von Prodazo, Julvrb, &, k, geot, Tetehe 
B10. 5 


meet 





_— 





THE ACTION OF THERMAL WATERS 999 
Tn some loose sands and sandstones there has sometimes occurred m 
curious which the microscope first ders avtlod, 


‘This is the precipitation on the outer surface of rounded 


of a greater or less amount of silica, which has been 
pap oai age! ity with that of the original noclel (gy 747) 
Eelam mp enmen se pes a 
inn cr a eS 

ina concent 
Staion, 

ti 

tom ges on oer the =e 


in perfect optical saris aaa 
Ralpeeeests RAS wa tenet 
definite 


sgBs Sin ashy = posi to der 
v or ashes it is to 
mine the constitution of the i Pan, ee ee a 
whose eruption gave rise to such patetals on the 
Thus the ashes and dust which fell at various attr Dr. Sorby) 


ITS en were oer fo lon bog Peeiere a pyroxene andesite.’ 


with rocks in sity 
can ly stir end out examination 
of their thin sections. The occurrence has acco! ‘been demon- 
strated of Norwegian rocks as boulders in the Counties, 


whilst Swedish and Finnish rocks are common in the drift of North 
Germany and Saxony. We now come to the diseussion of the meta- 
isin to rebitialls echoes are liable. ; 
metamorp! cat atmospheric agencies results in 
Na ition and disint peor "The constituents are, of course, 
fferently affected, my rapidity of disintegration demands the 
doctuspcaition ‘of one of the rineipal constituents, Such a con- 
stituent is felspar, which decom; under the influence of water 
charged with carbonic acid into in ; while the ucts of the 
decomposition of non-aluminous minerals are car tes, ferric 
oxide, and quartz. The minute aap poland anaes pre ten the 
Seaatomcaien, are not affected by these agencies, and hence are to 
be found in all clays and sands. 

‘Thermal waters ch: with various substances are common in 
all voleanic districts and play their part in the m hosis of 
rocks. In this way a volcanic rock may become through 
the percolation of such solutions ; and mic: jical examination has 
shown that portions of the Roche poner in Pembrokeshire, 
have had their porphyritic felspars exe into quartz by this 

cy. Whilst ects of the metamorphosis caused by atmo, 

ric agencies, mention should be made otiee fact that a movement 

is now in progress to assist the selection of building stones suitable 
for public edifices, by n microscopical examination of thin sections of 





1 Bee the interesting paper by J. Murray and A. Renard on ' Voleanic Ashes and 
Cosmic Dust' in Natwre, 1884, vol. xxix. p, 685. 


a 





ieee 7 
1000. ©6THE MICROSCOPE IN GEOLOGICAL INVESTIGATION 


the rocks tobe employed.! Obviously an increase in volume 
goes hi sian the sty of the rock % conmtteenty and this 
may seriously affect os stability of the rock as a’ mass. 

‘The intrusion of an igneous rock has generally an ene 
influence on the structure and mineralogical composition of 
surrounding mass, portions of which it can inelude and 
dissolve (contact-metamorphism). Sections from the 
igneous rock with one of sedimentary origin are shy intersting 

he nee is found to irl ene we 

new min such as ts, an ite, mi mee 
crystalline structure ont of non-crystalline wedineutary’ materials, 
The formation ee the new constituents points to the action of over: 
heated water and gases of various eae which accompany be 
eruption. Of very common occurrence is the 

fossiliferous chalk—which is amorphous carbonate of rtaarrhs a 
marble consisting of crystalline calcite in which no trace of organic 
life can be discerned. ‘The heat is often so intense as to fuse sand- 
stones into a brownish glass. 

Tt would be difficult to overestimate the utility of the miero- 
scope in questions relating to dynamic metamorphism, or that due 
to ‘earth-stresses," 

The deformation by movement has sometimes been so 
that the rocks have undergone a complete Fcoree nace 
structure being partially or oven wholly efficed. toma 
is of course langely transformed into rete hence under hi 
plasticity may, ‘be produced in bodies which are solid tinder ordi | 
cireumstances.* 

Chemical reactions must occur and must entail the formation of ‘ 
new minerals; for Spring ® has demonstrated the trath that chemical 
action can take place under excessive pressure without the applica- 
tion of external heat, 

‘These questions are now engaging wide-spread attention, and we 
may hope for welcome light being cast upon the vexed pny rc of < 
crystalline origin of the schists. These latter ene 
glassy matter, ‘but theirstructure often reminds one of that of 
rocks, The opinion is daily gaining ground that some of them 
amphibolites) are nothing but altered igneous masses, an Ea 
which is strengthened by the knowledge that igneous rocks 
into schists under the influence of dynamic metamorphism, 
transition through molecular rearrangement first "secle its Ris 
firmation as a truth by the aid of the microscope, Let us take, for 
instance, the case of a fel yyroxene rock. Under d) 
metamorphism the twin lamel! vf the lath-shaped felspars 
bent, actual fracture of the crystals may occur, and possibly re- 
crystallisation of the component substance in wife; the new felspar, 
being granular, will arrange itself approximately along the plans 
of schistosity. i 

The pyroxene, which in the case of a dolerite was light chocolate 


! CL. Klos, Zeits, der deutschen geol. Gesellschaft, Ba. xl. Peni eam 


# Trosoa, ‘ Flow of Solids,’ Proe. Inet. Meeh. Eng. 1878, x M1. 


3 Hull. Acad. Helgique, tom, xlix, 1880 (2), pe Bit, 





mass, one in which the Speahenusenois occur in wavy or 
parallel layers. In conjunction with this transformation a se 
tion or concentration of certain substances is 
‘his generally shows ite in the white tion veins common to 
‘moved’ masses. Molecular tension can always be recognised by the 
presence of optical anomalies. The extinction shadows over 
Tio ecticna as the stage i rotated,  phenontenoa Acndwn as taduloes 
extinction. Strain eventually overcomes the limit of elusticity, and 
there occurs granulation. The latter can be defined as rrpganee: res 
inl igaiponenm facta esos yee cy Wenn) bn 
edt quarts ad fara bes As a rule, this alteration is 


sla 1 en Ta the any ee SE ibeestal eee 

lie. ) ep aah caches fimo se ops the fine 
secondary aggregate sweeps round them in the manner characteristic 
of fluxion structure. 

The quartz-granules of metamorphosed strata ure sometimes 
observed to have lost the fluid inclusions so generally found in the 
quartz-grains of old sedimentary rocks, Hence it would appear that 
bless of such liquids is also a result of metamorphic action. 

Secondary minerals become developed through the same causes. 
Pyroxene and olivine pass into hornblende, lime-soda felspars are 
altered into albite (xoda- srecie and epidote de. Mica, both white 
and black, is generally dev nee along planes of movement, being 
formed at the'« expense of the sees or the ferro-magnesian con- 
stituent. 

The degree of meta tly influenced by chemical 
composition and varies acco! jut it must be well understood 
that metamorphism does on me a radical change in the 
elementary chemical composition. There has ensued rather a re- 

erystallisation and a new association of the pre-existing elements 
(Delease). The chemical constitution of a hornblende pehist formed 
by the metamorphism of a dolerite is neal identical with that 
Lihat Bette: the change has been here more mineralogical than 

jieal. 

Tn conclusion, dynamic metamorphism causes sandstones to pass 
Tig! Smnbypenl tag schists ; when beside into mica 
schists, rocks are altered into ites &e.; basic 
igneous aoe, into hornblendic, actinolitic or chloritie pete: 

‘The optical methods now in use enable the petrologist to determine 
the constituents of rock-masses with astonishing success. The colour 
of the mineral in transmitted light, the crystallographic outlines, 


¥ CL. ‘Recent Researchos in the Motamorphism of Rocks? by Dr. A. Geikia, i 
Natere, vol. xxvii. 1882, p. 31. y = 


7 


1002 THE MICROSCOFE IN GEOLOGICAL INVESTIGATION 


i doatlevetaction rtarceyetaleoe te (cubic) systems 
in a 
is that whi hh consid Sete hierar as S 8 Prelate : 
The admixture of an isomorphic substance can 
turbance inthe molecular equim ee proved that 
Ge eens Gaerne igre ce See 
and ci ‘longin; pater 

Joablenchosting. 7h tulocial eptal hese Bike DEG Ee 
cation of ure at right angles to its optical axis, and. 
glass may iven optical properties in the same manner. 

Mention may wel Herne tetas the a 
the mineral leucite, which is a most im) 
lavas of Vesuvius and the neighbourhood of Rome. It crystallises 
apparently in beautiful icositetrahedra (tig. ibe pe 


yr eos nly nt, 


a — Trine meson the large ones beg ith 
more or less double refraction with 
cided traces of twin-l 
This anomaly was for a 
plicable, till Klein 
erystals revert when heated to: 
a ot eosin of Letine rs 
property 
ze tk Tenino 
showingtwin. “lassical investigation ix; 
Ficlation ondetemaoed aie, originally crystallised in the regular sys 
(After Zirkel.) tem and that its present 

is owing to molecular change due to the 
reduction of temperature Corrie uy Pepe ‘It is 
worthy of notice that MM. F. pers fe or 
tically produced a leucite rock, ented of 
optical anomalies described above, | 


i 
Fiat 
ine: 


He 





aa 


Tho relation between optical characters and chemical constitu 
tion has received some degree of attention, and in the case of the 
felspar group has been accurately determined. Only the ‘quantitative’ 


1 Far « description of the so-called * Erbiteunge-Mikroskop,’ sou Grothe Pye 
kalische Kryetallographie Leiprigy 1886, pe 681 





PURIFYING CRYSTALS OF INCLUSIONS—ANALYSIS 1003 
of the sul can be dealt with here, and we must abstain 
oa intel ce aeons 


whose microscopical appearance 
leads the trained to draw conclusions. It is 
interesting, Tanetan tothe Gas tip areentai or yviolet-brown 


colour of some monoclinic pyroxenes is due, according to Knop, to 
the presence of a not unimportant quantity of titanium oxide in their 


very gh 
clinie eo are found to between 36° and 54°. 
their ches a thon aad eating scscect oe 
ie aiperans }, an the-varying. iron 
Letee ae ‘The subject has recently been investigated, 
ee iik,' and later by Doelter. As a general 
extinction angle may be said to be somewhat less in those 
Coon lghehopimperenstnipe Satire ete those rich in 
these substances. Tn. the awe ofthe, Hornblexies tielpatiire 
of the o] optical axis increases, according tT en 


of iron, whilst Wiik considers the extostion Gan 
to the wage ee The diversity parte aaarnas 
The ae the late ‘aes Schuster have established the im- 


plagioclase which be 
considered «s isomorphous mixtures of ae eae )8,040) and 
anorthite (Ca(al.)640,), the eee: and chemical characters stand 
in the closest possible each other. Hence, given the 
he Peay aes ch ee Mt ce, me chemical constitution is 
nown. if ing, wity. 
Sneath ppc fg ot, en 
tensi) t recently em 
yori Tey in the tion of, the isa of 


monazite in Brazilian sands* This mineral contains « large per- 
centage of didymium, and accordingly gives the bands characteristic 
for that element. 

The discovery of the presence of foreign inclusions in all minerals 
has led toa eee revolution in mineral-chemistry. In earlier 
days it was customary to analyse a mineral without questioning its 

rity. Hence the early analyses and the formule developed there- 

express the actual constitution plus the inclusions, Methods 
have now been invented by which the foreign matter can be removed, 
Advantage is taken of the difference that is usual between the 
reat gravity of the mineral and that of its inclusions, the so-called 
vy solutions ' being employed for the separation.’ Most sntis- 
factory results have been obtained by such means. In cases where 
the greatest accuracy is necessary, the apparatus designed by Dr. 


+ *Om forhillandet ee de ceaee egenmeaperna och den kemiska samman~ 
sattnis hos pyrown- och amphibol-arterna '"—Finska Vetensk. Soc. Forhdl. hal. vl 
xxiv. and vol, xx 






of Science, vol. xxvii. 1880, 


Hose \Uisrostoptocke Physiograpie, 
900, ef 4eg., (Engllalt edition ee soeenbaech 












icroscope reveals the presence 

of the silico-fluorides of the metals present in bed 

nature of the crystals a7) = be determined m 
The second method 

follows the usual method pes anal; 

is heated in a small platinum crucible w 

mass then evay with sul; 

A small quantity of the solw is bree ut 

Tf calcium is present in the mineral peo ou C 

form. Other quantities are treated with di 

The crystalline products, ant, are the tee 

optical methods. It is possible by Behrens’ 

presence of 0°0005 mgr. in « grain. 


1 Neues Jahrowed fir Mis ie, ho. Ba, ii. 

* Tho following works oan be consulted on this sul 
siner neven chewitsch-mikroskopischen Mineral- ! 
T. H. Behrens, Mikrochemische Methoden eur Mi ‘ 
Hanshofer, ache Reactionen, Braunochwelg, 
Héuctions microchimiques &. eristaus, Re. Bi ‘aa6; 
yopacke Phywapron ie, wok L a pp. 1-2 


ley, Rock forming Minerals, 











FOSSILISED WOOP—COAL 


Tn all cases it is advisable to Lert eae 
ee ee sheet of bras tae 
microscope played an important 
science of othe work on ‘ lek i 


§ 


transparent sections are needed i 

tion ; but such sections, though made with Se 
is the fossilising material, require much labour and skil 

has to be dealt with, Occasionally, howover, it has happened that 


the infiltration has filled the apr posite area one te 
out consolidating their walls; and as the latter have 1 0 


it 
tolerably close resemblance to the woods of the existing period : 
thus the. onlinary structure of dicotyledonous and tino ile 
Hip tenets + lignites = the utmost: perfection ; 
and the peculiar modification presented by coniferous wood is 
most. distinctly exhibited, As we go back, » through 
strata to the Secondary period, we more and more rarely meet with 
the ordinary dicotyledonous structure ; and the lignites of the earliest 
deposits of these series are, almost universally, either gymnosperms ™ 
or 


8. 
ding into the palwozoic series, we are presented in the 
be} coal formations of our own oe other een with an Bere 
fina: of the prevalence of a most luxuriant vegetation in a 
axaadvely early period of the world’s agar The determina~ 
tion of the characters of the Ferns, Sigillaria, Lepidodendra, Cala- 
mites, and other kinds of vegetation whose forms are ved in 
the shales or sandstones that are interposed between strata of 
coal, has been hitherto chiefly based on their external characters ; 
since it is seldom that these specimens present any such traces 
of minute internal structure as can be subjected to microscopic 
elucidation. But persevering search has recently brought to light 


4 Under this head are included the Cycadea, along with the oniinary Gontfera, 
or pine and fir tribe. 





1006 THE MICROSCOPE IN GEOLOGICAL INVESTIGATION 


numerous examples of coal-plants whose internal structure is suf- 
ficiently well preserved to of its studied microscopically ; 
and the careful researches of Professor W. ©. Williamson have shown 
that they formed a series of connecting links between 

and flowering plants, being obviously allied to Aquisetacea, 
podiacee, &e., in the character of their fructification, whilst 
‘stem-structure foreshadowed both the ‘endogenous’ and ‘exogenous’ 
types of the latter.' Notwithstanding the general absence of 
definite, form in the masses of decomposed vegetable matter of whi 
coal itself consists, the traces of structure revealed by the microscope 
are often sufficient—especially in the betes terme coal— 
nob only to determine its table origin, in some cases to 
justify the botanist in cays fe ae character of the —— 
from which it must have been derived ; and even where the stetns 
and leaves are represented by nothing else than a structureless mass 
of black carbonaceous matter, there are found ditfsed through this 
«multitude of minute resinoid yellowish brown xeanules, which are 
sometimes aggregated in clusters and inclosed in sacculi; and these 
muy now be pretty certainly affirmed to represent the spores, while 
the sacculi represent the sporangia, of gigantic L, 

of the Carboniferous flor. The ae the ion of these 
granules, the brighter and stronger is the flame with which the coal 
burns; thus in some blazing cannel-coals they abound to such o 
degree as to make up the greater ‘ion of their substance ; 
whilst in anthracite or ‘stone-coal’ the want of them is shown by 
its dull and slow combustion. It is curious that the ion of 
these resinoid granules through the black carbonaceous matter is 
sometimes so regular as to give to transparent sections very 

the aspect of a section of vegetable cellular tissuc, for which 
have been mistaken even by experienced microseopists ; but 
resemblance disappears under a more extended scratiny, 
shows it to be altogether accidental.* 

Passing on now to the Animal Kingdom, we first cite some 
parallel cases in which the essential nature of deposits that forms 
very important part of the earth's crust has been determined by the 
assistance of the microscope, and then select a few examples 
the most important contributions which it hasafforded to our: 
ance with types of animal life long since extinct. It is an admitted 
rule in geological science that the past history of the earth is to be 
interpreted, so far as may be found ible, by the study of the 
changes which are still going on. "Thus, when we meet 
extensive stratum of fossilised Diatomacem in what is 
land, we can entertain no doubt that this silicious deposit 
ally accumulated either at the bottom of a fresh-water lake or 
the waters of the ocean ; just as such deposits are formed at 
present time by the production and death of sucvessive 
of these bodies, whose indestructible casings accdmulate in the lapse 


a 


EU 


hio succession of momoire on the coal-plante in the recent yolames of the 
tes upon methods to be employed in making preparations of coal, see 
1. 


ly of Hocks, 1884, p. 7 






ROCKS IN FORMATION BY MICROSCOPIC ANIMALS 1007 


of 80 as to form layers whose thickness is limited | 
Sebaldineny duis gowiial this process pong pian be sated 


fine white mud which is brought up from almost every part of the 
sea-bottom of the Levant, where it forms a stratum that is continually 
Eaidergoing » slaw bobeleyly soceeeme katie Gentbe aie fic re- 
searches of Professor W. C. Williamson! have shown, not only that it 
Steal and vogeatle et thabiaocattnaly ocelot sonora 
animal and », but itis entirely or: tw com) 

of such remains. Amongst these are seat twenty-six Dia- 


z 


tomacere (silicious), ne species of Foraminifera (calcareous), and a 
miscellaneous a roy objects (tig. 749), consisting of calcareous and 
silicious spic Gorgonia, ents of the 
calcareous skeletons inoderms and molluscs. collection of 


forms strongly resembling that of the Levant mud, with the exception 
of the silicious Diatomacem, is found in many parts of the vcabeaies 
grossier’ of the Paris basin, as well as in other extensive deposits of 
the same early Tertiary period. 

It is, however, in regard to the great chalk formation that the 
information afforded by the microseope has been most valuable, 
Mention has already been mace of the fact that a large proportion 
of the North Atlantic sea-bed has been found to be covered with an 
‘ooze’ chiefly formed of the shells of Globigerine:; and this fact, first: 
determined by the examination of the small quantities brought up 
by the sounding apparatus, has been fully confirmed by the results 
of the recent exploration of the deep-sea with the dredge ; which, 
bringing up half a ton of this deposit at once, has shown that it is 
‘not a mere surface-film, but an enormous mass whose thickness cannot 
be even guessed at, * Under the microscope,’ says Professor Wyville 
‘Thomson * of a sample of 1} ewt. obtained by the dredge from Bebo 
of nearly three miles, ‘ the surface-layer was found to consist chiefly 
of entire shells of Globigerina bulloides, large and small, and of frag- 
ments of such shells mixed with a quantity of amorphous calcareous 
matter in fine particles, a little fine sand, and many spicules, portions 


1 Memoirs of the Manchester Literary anit Philosophical Society, wol. vil 
* The yt Aa ‘the Sea, 410. sas %, 





1008 THE MICROSCOPE IN GEOLOGICAL INVESTIGATION 


spicules, and shells of Radiolaria, a few spicules of and 

fe iota inn Below the surface-layer the it be- 

“ee go mir, canes tro 
onal iene 


ine mig become: 
Deer eal oalestecoroait ee aed data a ae 


* O3x% 








x = 
a 
® 
Levant mud: A, ©, D, allicious 
1 Tethge DH pene ‘of Geodia ; KE, cwlonreous of 
rantia F, G, M0, ee eee ee ri 
I cabettous tphonle 0 Gorsenia Ke 1,8, siliclous epicales of wponges; 


B, portion of prismatic layer of ahell ot 2 


division, is in greatly preponderating proportion. One can have 
doubt, on ream tnie tel ediment, that it is formed in the main 
the accumulation and disintegration of theshells of iperyievs the 
shells fresh, whole, and living, in the surface-layer of 

and in the lower Jayers dead, and gradually crambling down by the 
decomposition of their organic cement, and by the pressure of the 
Jayers above.’ This white calcarcous mud also contains in large 





amorphous parti of nevertheless, 
beoonbei ‘ions of bei pride Ay of similar 


shells, or of larger calcareous organisms, In chalk of some 
localities the disintegrated prisms of Pinna, or of other large shells 
a the es steastey( dea a ay Stee er oe ee Ee 
recognisable components ; whilst in cases, again, the chief part 





Fis, 750—Microscopic organisms in chalk from Grayesond: a, 
Testutaria glovubea; ore, ¢ Rotalla axpera; f, Textularia eas 
 Planularia hezaa; h, Navicula, 





is made up of the aes Cytherina, serine Sent ‘of entomo- 
atracous crustacean. Different specimens of cl tly in 
the proportion which the distinctly i aaataaee Lae is 
amorphous residuum, and which the different kinds of the former 
Dear to each other ; and this is quite what might be anticipated when 
we bearin mind the predominance of one or another tribe of animals 
in the several parts of a Jarge area ; but it may be fairly concluded, 
from what has been already stated of the amorphous com it of 
the Globigerina-mud, that the amorphous constituent of chalk like- 
wise is the disintegrated residuum of foraminiferal shells. But, 
further, the Globigerina-mud now in process of formation’ is in some 
places {iterally crowded with sponges having a’ complete’ siliclous 
3r 





1010 THE MICROSCOPE IN GEOLOGICAL INVESTIGATION 


skeleton; and some of them bear such an extraordinarily close r- 
‘semblance, alike in structure and in external form, to the Ventriculifes 
which are well known as chalk fossils, as to leave no reasonable doubt 
that these also live ag silicious sponges on the bottom of the. creta- 
ceous sea. Finally (ns was first pointed out by Mr. Sorby) the cooco- 
liths and heres at present found on the sea-bottom are often 
to be discor by the mi ic examination of chalk.’ All 
these correspondences show that the formation of chalk took place 
under conditions essentially similar to those under which the deposit 
of Globigerina-mud is being formed over the Atlantic sea-bed at the 


present time, 
In examining chalk or other similar mixed whose 
component particles are easily separable from , it ix de- 





Fra, 753.—Microscopio isms in chalk from Meudon, seen partly as 
opaque, partly as transparent objects, 


simble to separate, with as little trouble as possible, the langer and 
more definitely o1 bodies from the minute 


amorphous particles: 
and the mode of doing this aioe upon whether we are operat- 


to the method of levigation already directed for separating the 
Diatomacee. It will usually be found that the first contain 
the larger Foraminifera, fragments of shell, &e., and that the smaller 


1 ‘On the Organic Origin of the so-called “ Crystalloide” of Challe! in Amm,. 
Hick, ser. iii, vol. vii, Teale Pp. 19-200, es 


and 

examining such 

chips as may be obtained with a hammer will commonly serve very 
Sat grea translucent flint being tirst selected, and the chips that 


in Canada balsam. ‘The most perfect specimens of 
however, are only to be obtained by slicing ish 

There are various other deposits, of less extent importance 
Say prenial cae rae meen 
part of ypic ‘isms, chiefly minute Foraminifera ; and the 
presence of animals of this group may be largely recognised, by the 
assistance of the microscope, in sections of calcareous 
various dates, whose other materials were fragmenta of corals, 
ery sr sakes peepee ances aie bed 

fine crag (Tertiary) eas 

faethe geistsh dares bah tha Teter inentodned tak rote 
chiefly built consists almost exclusively of the shells of Miliolida, 
and is thus known as miliolite (millet-seed) limestone. In the vast 
stratum of nummulitic limestone which was formed at she com. 


; 
F 
5 
Hi 
i 


a 


the microscope to have been chiefly composed of foraminiferal 
coalies cmelartaraprierap emt eegen ere ie sim ae 
ment from which the rock derives its name (such as is beauti! 

Pe aey in many specimens of Bath stone and Portland stone), it 
is found by microscopic examination of transparent sections that 


veous formations, the entire materials of which were obviously fur- 
nished by the accumulation of animal remains, it not unfrequently 
happens that all traces of their origin are obliterated by* ic’ 
action ; and thus a crystalline marble, whose present not 
the least evidence of organic arrangement, may have been formed by 
the metamorphosis of chalky, Oulitic, or nummiulitic limestone, Now 
there is very strong evidence that the vast mass of sul 

‘carboniferous’ limestone which forms our coal-basins has had a 
similar origin in foraminiferal and zoophytie life the traces of 

T 


— 











SSS 


1012 THE MICROSCOPE IN GEOLOGICAL INVESTIGATION 


hich have been for the most removed by the metamorphic 
BEES aavaieed in ie upheaval or wave Of hey cones eh 
thickness. 


Foraminifere (of which the Saccamina has come down to the present 
time), and the ‘tiful polyzoaries known ax ‘lace-corals." 

Mention has been already made of Professor Ehren! very 
remarkable discovery that ial eee: (to say the least) of the 
green sands which present themselves in various stratified deposits, 
from the Silurian epoch to the Tertiary and which in certain 
localities constitute what is known as the Greensand formation (be: 
neath the chalk), is composed of the casts of the interior of minute 
shells of Foraminifera and Molluscs, the shells themselves hay 
entirely disap) The ay eins material of these breech toa 
mervly filled the chambers and their communicating passages, but | 
also penetrated, even to its minutest ramifications, the canal-system 
of the intermediate skeleton. ‘The precise to these deposits 
presents itself in certain spots of the existing sea-bottom, such as 
the Agulhas bank, near the Cape of Good Hope, where the dredge 
comes up laden with a ies sand, which on microscopic examina~ 
tion proves to consist almost entirely of ‘internal casts” of existing 
Foraminifera. 

It is, however, in the case of the teeth, the bones, and the dermal 
skeleton of vertebrated animals that the value of microseopic inquiry 
becomes most apparent ; since their structure presents 80 7 
characteristics which are subject to well-marked variations in 
several classes, orders, and families that a knowledge of these cha- 
racters frequently enables the microscopiat to determine the nature 
of even the most fragmentary specimens with a positiveness which 
must appear altogether misplaced to such as have not studied the 
evidence, It was in regard to teeth that the possibility of such 
determinations was first made clear by the laborious researches of 
Professor Owen ;! and the following may be given as 
their value :—A rock-formation extends over many parts of 
whose mineral characters might justify its being Timed elther to 
the Old or to the ‘ew Red Sandstone of this country, and whose 
position relatively to other strata is such that there is great di 
in obtaining evidence from the usual sources as to its place in the 
series, Hence the only hope of settling this question (which wat 


i 


» Seo his Ovlontography. 


lll 


DETERMINATION OF FOSSIL TEETH AND BONES 1013 


unmistakably proved them 
us of fishes (Dendrodus) which is exclusively palwozoic, and thus 
Secided that the formation mast be Old Bed. So, again, the micro- 
examination of certain fragments of teeth found ina sandstone 
of Warwickshire disclosed a most remarkable type of tooth-structure 
{shown in fig. 752), which 
was also ascertained to 


the ‘ Keupersandstein * of 
Wiirtemberg; and the 
identity or close resem~ 
anne the cis to 
whi ese teeth belonged 
having been thus esta- 
blished, it became almost. 
cortain that the Warwick- 
shire and Wiirtemberg 
sandstones were equiva- 
lent formations, a point. 
of much apes import 
ance. ors pea 
arising out of is dis- 2 

Ses tho nture of £!%-75%—Seotion of tooth of Ladyrinthodon. 
the animal (provisionally 

termed inthodon, a name expressive of the most peculiar 
feature in its dental structure) to which these teeth 

‘They had been referred, from external characters merely, to the 
order of saurian tiles; but it is now clear that were 
gigantic salamandroid Amphibia, having many points of relationship 
to Ceratodus (the Australian ‘mud-fish’), which shows a similar, 

‘h simpler, dental o1 isation. 

6 researches of Professor Quekett on the minute structure of 
bone! have shown that from the average size and form of the lacunie, 
their disposition in regard to each other and to the Haversian 
canals, and the number and course of the canaliculi, the nature of 
even a minute fragment of bone may often be determined with a 
considerable approach to certainty, as in the following examples, 
among many which might be cited :—Dr. Falconer, the distinguished 





1 Soe hin memoir on the ‘Comparative Structare of Bone’ in the Trans. Micros. 
Soo. ser. i. vol. ii.; and the Catalogue of the Histological Museum of the Roy. Call, 
‘of Surgeons, <0. ji. 





SSS 
1Ot4 THE MICROSCOPE IN GEOLOGICAL INVESTIGATION — 


peek ore abbr peace fc ae 
of the gigantic fossil votisho at the Siva 

Se cialotais coal bones about which fopiontars 2! 

them for minute examination in Sipe oa, 


roscopic evidence, that 
be pronounced reptilian, and probably to omental = 
tortoise tribe; and this determination was borne out by other 
evidence, which led Dr. Falconer to conclude that they were toe 
bones of his great tortoise. Some fragments of bone were found, 
many years since, in a chalk-pit, which were considered by Professor 
Hehe pearcippiadamim yn ter Ea LE 
bird allied to the albatross, This determination, founded solely on 
considerations derived from the very im: ly preserved 

forms of these fragments, was called uestion by some other 


tologists, who thought it more that these bones 
Erg es bee eperane ee aed 


was extended u 
digit. "So specie of terihtyih hoverer, at al frie et 
this in dineiesiaese at that time known ; 
Precip bean ne itp mini heehee Tare 
decisive, the question would have long remained unsettled 
brik Ung eines hair erie ana Tha piel an 
decisive, by showing that the minute structure of the bone in 


tion maded ‘Bet thatof lo bone, and 
cosea tially from atered that no one who placed 
much rellaais ‘upon that on aides ale ent 


tertain. epee = 
on the matter, By Professor Owen, however, the validity of 
determination was questioned, and the bone was still pli ee 
be that of a bird, until oe eee at om COR 
value of the Ppncame trium tly confirmed, by the discovery 
of undoubted pterodactyle bones of corresponding and even of greater 
dimensions in the same and other chalk quarries. 

‘The microscopic examination of the peti now in course of 
deposition on various parts of the great oceanic area, and 
of the large number of samples brought up in the ‘| 
ings, has led to this very remarkable conclusion—that the débrix 
resulting from the degradation of continental land-masses are not 
carried far from their shores, being entirely absent from the bottom 
of the ocean-basins. The sediments there found were not of 
organio origin, mainly consist of volcanic sands and ashes, which are 
found in voleanic areas, and of clay that seems to have been pro- 
duced by the disintegration of masses of pumice (vesicular lava), 
which, after long floating and dispersion by surface-drift or oeean- 
currents, have become water-l and have sunk to the bottom. 
As no ordinary silicious sand is found ar mee save in the neigh- 
bourhood of continents and continental ds, and as all oceanic 
islands are the products of local voleanic persis this absence of 
all trace of submerged continental land over the great oceanic area 
affords strong confirmation to the belief which geological evidence 
has been gradually tending to establish, that 
which form the existing land were Samual in the immediate 


— 


P 


ORIGIN OF UCEANIC AREAS 1015, 


neighbourhood of pre-existing land, whose degradation furnished their 
materials ; and consequently that the original disposition of the 
great continental and oceanic areas was not very different from 
what it now is! Further, the microscopic examination of these 
oceanic sediments reveals the presence of extremely minute particles, 
which seem to correspond in composition to meteorites, and which there 
is strong reason for regarding as ‘cosmic dust’ pervading the inter- 
planetary spaces. Thus the application of the microscope to the 
study of these deposits brings us in contact with the greatest 
questions not only of terrestrial, but also of cosmical physics, and 
furnishes evidence of the highest value for their solution. 


1 See Professor Geikie’s lecture on ‘Geographical Evolution’ in the Proc. Roy. 
Geog. Soc. July 1879; also‘ A Search for Atlantis with the Microscope,’ by the same 
author, Nature, 1882, p. 25. 





1016 


CHAPTER XXIV 


ORYSTALLISATION. POLARISATION, MOLECULAR 
COALESOENCE 


uly 


miner remarkable either for the elegance of their 
for, the beauty of their colours, or for both combined. 
forms of in substances, when in any way 

in virtue of that peculiar arrangement of their molecu! 
termed crystallisation ; and each subject which erystallises at 
so after a certain type or plan, the identity or difference 
types furnishi: ciabiar ict qeeaenersio aaa 
It does not follow, however, that the form of the crystal 
constantly the same for each substance ; on +, the mmo 
lan of crystallisation aay Seale itself under a Restle 
rma; asa the  stody these in such minute crystals ax are 
appropriate subjects for observation by the microscope is not 

a very sniereating 62) sepllsation Gb ts pow; Bat i aaee 

ing some valuable hints to the desi, This is particularly 

case with erystals of snow, which bel fe) to the -hlagoa pi 

the basis of every figure being being a hexagon of six rays the 
‘become incrusted with an endless variety of secondary 

of the same kind, some consisting of ‘ato, pai sass 
solid but translucent prisms hea) pon another, and others 
gorgeously combining lamine an in va richest 

the angles by which these figures are bounded being in’ 

or 120°, Beautiful arborescent forms are not anfreq! 

by the peculiar mode of aggregation of individual 3 Of 
we have often an examploon # large scale on a window ; 
microscopic erystallisations sometimes present the same curious 
phenomenon (fig. 753). The Mineral mys presents 
interesting microscopic objects : avanturine, lapis Inzuli, cryin 
silver, &c. make very good specimens ; whilst thin sections of granite, 
gabbro, and other rocks of the more or less regularly 


rs jOlaisher on 'Snowcrystals in 1865,’ Quart, Journ. Micros. Sef. vol. iif. 1855, 
p. 179, 


20 =| 
fi 


3 


zeiS? 





recommenee with increased rapidity. This interesting spectacle 
may be watched under any but the instrament specially 
eee Ey hmann! is ‘ly adapted to studies of this 
‘ind. The degree of heat can be varied at will. The phenomena 
become far more striking, however, 
when the crystals, ag come into 
being, are made to stand out bright 
upon a dark ground, by the use of 
the 5 spot lens, the paraboloid, or any — 
other form of black-ground illumi- 
nation ; still more beautiful is the 
spectacle when the polarising appa- 
ratus is employed, so as to invest 
the crystals with the most gorgeous 
variety of hues, : 
By chemically precipitating erys- 
talline products ee ey pros 
we can ol un a 
insight into the crystallisation 
cess. One of the earliest workers 
at this subject was Link in 1839. 
He observed that the ag ane 
first wed in the form of v 
minute liquid globules, which ran together and eventually by almost 
insensible lations passed into the solid and crystalline condition, 
In fact, the deposition of crystalline precipitates out of solutions 
seems mostly to occur in this way, Carbonate of lime is a good 
instance of this, the liquid globules finally arranging themselves 
into the little rhombohedra Vases to the substance. On the 
temperature of the glass slide during the solidification depend 
the aah and prsecenney of the tle are ‘Thus santonine, when 
erystallising rapidly on a vw jot plate, forms lar; 
radiating from centres mine canes 3 aan tie heat is 
less considerable the crystals are smaller, show concentric 
waves of very decided form (fig. 754) ; but when the slip of glass is 
cool the erystals are exceedingly minute. In the case of sulphate of 
copper, Mr, R. Thomas? succeeded, by keeping the slide at a 


4 ‘Veber Krystallanalyse,’ Pogg. Ann. Palfxiti, 1881, pp. 500-622, 
4 Soo his paper ‘On the Crystallisation of various temperatures of the Double 














tors CRYSTALLISATION, POLARISATION, F 


temperature of from 80° to 90°, in obtaining m« 
beautiful forms of spi stallisation, such as thy 
fig. 755, Mr. Slack has n that © great varie 
curved forms can be obtained by dissolving metallic, 
santonine, &e. in water Sor 

silica, The nature of the action that takes 

stood by allowing a of thee silica solution to d 
the result of which will be the production of a com 
peta mer esters er ras When a group 
mation to radiate from a centre, the contract 
will often give them a tangential pull. Anothe 
silica is to introduce a very slight curling with ju 





Fio. 764.—Radiating erywtallisation of santoni 


tion above the slide to exhibit fragments of Newto 
is illuminated with Powell and Lealand’s modifica! 
Smith’s dark-ground illuminator for high powers, | 
a Ath objective. With crystalline bodies these 
the variety of colours to be obtained with the 
best slides exhibiting a series of tertiary tints." 

results may often be obtained from a mixture of t 
and some of the double salts give forms of peculing | 
mann has done excellent work in this departmen: 
must be had to his papers in the ‘ Zeitschrift fiir 
for a deseription of the phenomena such mixtures ¢ 





Sulphate of Magnosia and Sulphate of Zine,’ in Quart, Ja 

p. 187,177, See also H. N. Draper on *Crystals for th 
lectwal Observer, vol. vi. 1865 p. 487. 

ion the Employment of Collcid Sion in’ the Preparation 

Polariscope,’ in Monthly Micros. Jowrn. v. p50. 











DICHROISM 1019 


¥wing list specifies the salts and other substances whose crystalline 
yems are most interesting. When these are viewed with polarised 
ight some of them exhibit a beautiful variety of colours of their 
"wn, whilst others require the interposition of the selenite plate for 
he development of colour. The substances marked d are distin- 
{ished by the curious property termed dichroism, which was first 
aoticed by Dr. Wollaston, and specially investigated by Sir D. 
Brewster. This property consists in the exhibition of different 
eolours by these erystals, according to the direction in which the 
light is transmitted through them, a crystal of chloride of plati- 
mmm, for example, appearing of a deep red when the light passes 
slong its axis, and of vivid green when the light is transmitted in 
‘@he opposite direction, with various intermediate shades. It is only 
Weasessed by doubly refracting substances ; and it depends on the 








Fro. 755.—Spiral crystallisation of sulphate of copper. 


pei! dese of some of the coloured rays of the light which is polar- 
ised during its passage through the crystal, so that the two pencils 
formed by double refraction become differently coloured, the degree 
of difference being regulated by the inclination of the incident ray 
to the axis of double refraction. 





Acetate of Copper, d Bitartrate of Ammonia 
» _ Manganese Lime 
” Boda Potass 
» Zine Boracic Acid 
Alum Borate of Ammonia 
Arseniate of Potass » Soda (borax) 
ine Carbonate of Lime (from urine of 
‘Aspartic Acid horse) 
Bicarbonate of Potass » — Potass 
Bichromate of Potass » , Boda 
Bichloride of Mercury Chlorate of Potass 
Binoralate of Chromium and Chloride of Barium 


» Cobalt 





1020 ORYSTALLISATION, POLARISATION, ETC. 
CMorideof Copper and Ammonia Phosphate of Ammonia 
pieene aa . a 
Soda 


Chromate of Potass 
Cinchonoidine Platino-chloride of ‘Fballiunt 
Citric Acid. Platino-cyanide of Ammonia, d 
eee of Mercury Prussiate of Potass eae 
ic Acid ” ” 
ee ae of Potass ‘Quinidine 
rt ees faligiaine 
Mannite Santoning 
oe ‘Stearine 
Muriate of Ammonia Sultiate ‘of Ammonia 
‘Nitrate of Ammonia Cadmus 
2 Bismuth = Copper ma Ammonia: 
” Copper Copper an Magnesia 
Bota Copper and Fotass 
* Strontian Irom and Cobalt 
ts Urania ” esi, 
Oxalle Acid 4 
‘Oxalate of Ammonia » — Potassa 
» Chromium » Boda 
» Chromium and Ammonia, d Zinc 
Chromium and Potass, @ Tartaric Acid 
» Lime ‘Tartrate of Soda 
» Potass Urie Acid 
» Soda ‘Urate of Ammonia 
Osalurate of Ammonia » Soda 


Tt not unfrequently that a beautiful speci 
coon f orpatallis as davntcpn taste idan tii naee er Sore 
keep for display. In order to do this successfully, it is necessary to 
es EA and Mr. Warrington recommends castor oil as the 
best preservative. A small pee this should be poured on 
the crystallised surface, a gentle warmth ied, and a 
cover then laid upon the drop and gradually pressed down ; and 
after the superfluous oil has been removed from the margin a coat 
‘of gold-size or other varnish is to be applied. Although most of the 
objects furnished by vegetable and animal structures, which are 
advantageously shown by polarised light, have been already noticed 
in their appropriate Bass, it will be useful here to rveapitulate the 


principal, with some 


Vegetable Polyzoaries 
Cuticles, Hairs, and Scales, from Leaves Tongues (Palates) of Gasteropods 
Fibres of Cotton and Flax mounted in balan 
Raphides ; Cuttle-tish bone 
Spiral cells and vessels Scales of Fishes 
Starch-grains Sections of abe 
Wood, longitudinal sectionsof, mounted ” irs 
in balsam ” Qailis 
: ” Horns 
Animat Of Shells 
Fibres and Spicules of Spon; » Skin 
Polypidome of Hydrogoa » Teeth ; 
Spicules of Gorgonias » ‘Tendon, longitudinal 








CONCRETIONARY 1021 


manent for of exystallianble substances, when tho aggro. 
rms 
gai af th hong arts aks pln nthe of certain 

ira mag ear eg and « class of facts of great interest in 
their bearing pear fon the mode of formation of various calif struc. 
tures in animals was light ingenious 
pe tp . Rainey,! whose of i bi Bec serntr 
conisted in bringing abut a dow decomposition of the salta of Iie 


The Soot is eiectaa of aS ma peosiemare 
lime, whi i crease in diameter at expense of an 
amorphous uonewtiae 


Seed eens epeniieaial 
to correspond very closel pe hpreripe yon concre- 
tions which are common begin rca te 
at one time supposed to have a matrix of cellular structure. The 
small calcareous concretions termed ofoliths, or ear-stones, found 
pingennen upriigiomgs nape pee mS 


the same. 
Similar concre' spher- 
oids have already been men- 
tioned as occurring in the 
skin of the shrimp and other 
pee calcified shells 
af Crustacea ; they oocur 
also in certain im 
layers of the shells of Mol- 
lusca ; and we have a very 


the outer Inyor of the en- 
velope of what is commonly 
known as n ‘soft ogg,’ oran 





‘egg without shell,’ the cal- 
careous deposit in re fibrous Fro. 756.—Artificial concrotions of 
inn already described carbonate of lime, 


ere insufficient to 
Tn the external layer of an ordinary egg-shell, on the 
slit i the concretions have enlarged themielves by the pro- 
fas accretion of calcareous particles, so as to form a continuous 
yer, which consists of a series of polygonal plates resembling those 


1 Sop his treatise ‘On the Mode of Formation of the Shells of Animals, of Bone, 
and of saver! other structures, by a process of Meleoalar Coalenceace, 

fn eortain artificially formed peslincke; te,’ 1858; and his ‘Purther Experiments and 
Oberevations' ia Quart. Journ, Micros. Sei. n.s. vel. b. 186}, ps 28) 











1022 ORYSTALLISATION, POLARISATION, 


of 0 eee Sogate In the solid ‘ shells" 
ostrich cassowary this concretionary i 
thickness ; and vertical as well as horizontal secti 
interesting objects, showing also beautiful effects of ¢ 
ised light. And from the researches of Professor! 
on the scales of fishes, there can be no doubt t 
calcareous deposit which they contain is formed up 
This line of inquiry has been contem 

Professor Harting, of Utrecht, who, working 
mentally the same as that of Mr, Rainey (viz. the; 
of insoluble salts of lime in the presence of an ¢ 
has not only confirmed but greatly extended his 
that with animal colloids (such as egg-albumen, 
solution of gelatine) a much greater variety of i 
produced, many of them having a strong resembla 
structures hitherto known only as occurring in the 
of various classes, The mode of experimenting us 
Professor Harting was to cover the hollow of an ¢ 
late with a layer of the organic liquid to the dey 
be of an inch, and then to immerse in the bore 
but at diametrically opposite points, the solid sali 
on one another by double decomposition, such as 
or acetate of lime, and carbonate of potash or so¢ 
very gradually dissolved, the two substances may ¢ 
n each other, and may throw down baad > | 

of the ‘colloid.’ The whole is then cot wi 
and left for some days in a state of perfect tranqui 
begins to appear at various spots on the surface 
flecting light, which gradually increase and coalese 
crust that comes to adhere to the border of the plat: 
portion of the precipitate subsides, and covers t] 

plate, Round the two spots where the salts are 
instance the calcareous decate have a different | 
in the same experiment several very distinet prodi 
obtained, each in some particular spot. The length 
is found to vary with the temperature, being gene 
eight weeks. By the introduction of such a coli 
madder, logwood, or carmine, the concretions tab 
one employed. When these concretions are tre 
acid, so that their calcareous particles are whol 
there is found to remain a basis substance which p 
of vach ; this, which consists of the ‘colloid’ some 
termed by Harting calco-globuline, Besides the glo 
with the uliar concentric and radiating arran 
by Mr. Rainey (fig. 756), Professor Harting < 
variety of forms bearing some resemblance to the fc 
‘discoliths ' and ‘ cyatholiths’ of Professor Huxley 
culated ‘spicules’ of Alcyonaria, and the very simil 
mantle of some species of Doris, 3, Lamelle of 
substance,’ which are very closely imitated by | 
fattened polyhedra, found’ on the surface of the 


DETECTION OF MINUTE QUANTITIES OF POISON 1023 


theroidal concretions which form a sort of rudimentary shell within 
ve body of Limaz. 5. The sinuous lamelle which intervene between 
9 el plates of the ‘sepiostaire’ of the cuétle-fish, the imitation 

is being singularly exact. 6. The calcareous concretions that 
ive solidity to the ‘shell’ of the bird’s egg, the semblance of which 
‘refessor Harting was able to produce in situ by dissolving away 
ne calcareous component of the egg-shell by dilute acid, then im- 
versing the entire in a concentrated solution of chloride of 
alcium, and transferring it thence to a concentrated solution of 
arbonate of potass, with which, in some cases, a little phosphate of 
oda was mixed.' Other forms of remarkable regularity and definite- 
yess, differing entirely from anything that ordinary crystallisation 
would produce, but not known to have their parallels in living bodies, 
have been obtained by Professor Harting. Looking to the relations 
between the calcareous deposits in the scales of fishes and those by 
which bones and teeth are solidified, it can scarcely be doubted that 
the principle of ‘molecular coalescence’ is applicable to the latter, 
as well as to the former ; and that an extension and variation of this 
method of experimenting would throw much light on the process of 
tasification and tooth formation. The inquiry has been farther pro- 
tecuted by Dr. W. M. Ord, with express reference to the formation 
of urinary and other calculi.” 

Micro-chemistry of Poisons.—By a judicious combination of 
microscopical with chemical research, the application of reagents 
may be made effectual for the detection of poisonous or other sub- 
stances in quantities far more minute than have been previously 

to be recognisable. Thus it is stated by Dr. Wormley# 
that micro-chemical analysis enables us by a very few minutes’ labour 
to recognise with unerring certainty the reaction of the yryygoth part 
of a grain of either hydrocyanic acid, mercury, or arsenic ; and that 
in many other instances we can easily detect by its means the presence 
of very minute quantities of substances, the true nature of which 
could only be otherwise determined in comparatively large quantity, 
and by considerable labour. This inquiry may be prosecuted, how- 
ever, not only by the application of ordinary chemical tests under 
the microscope, but also by the use of other means of recognition 
which the use of the microscope affords. Thus it has been shown that 
by the careful sublimation of arsenic and arsenious acid, the subli- 
mates being deposited upon small discs of thin glass, these are dis- 
tinctly isable by the forms they present under the microscope 
(especially the binocular) in extremely minute quantities ; and that 
the same method of procedure may be applied to the volatile metals, 
mercury, cadmium, selenium, tellurium, and some of their salts, and 
to some other volatile bodies, as sal-ammoniac, camphor, ani sulphur. 
The method of sublimation was afterwards extended to the vegetable 

1 See Prof. Harting's Recherches de Morphologie synthétique sur la luction 

ifciellede quelques Formations Caleaires Inorganiquee,publiées par ! Académie 
Royale Neer Handaise des Sciences, Amsterdam, 1879; and Quart, Journ, Micros. 

ee ie troatne On the Influence of Colloids upon Crystalline Form and 


79, 
3 Micro-chemistry of Poisons. 





1024 CRYSTALLISATION, POLARISATION, 


alkaloids, such as morphine, strychnine, veratrine, 
quently it was shown that the same method cou 
tended to such animal products as the constitue 
and of urine, and to volatile and decomposable o1 
generally. By the careful prosecution of micro~ 
especially with the aid of the spectroscope (where 
detection of poisons and other substances in very 
can be accomplished with a facility and certain 
formerly scarcely conceivable. 


APPENDICES AND TABLES 


USEFUL TO THE MICROSCOPIST 

















1027 
























APPENDIX A 
TABLE OF NATURAL SINES 
es es ee 
4 “0131 goed | -7254 | “7284 
\s 7343 | -7373 | -7402 
a 7460 | -7489 | +7518 
| -0567 ‘1576 | “7604 | -7632 
‘ovat “7688 | 7716 | “7744 
“0915 °7826 °7853 
“1089 7983 | -7960 
8038 | “8064 
8141 | -8166 
‘8241 8266 
‘8339 “8363 
8431 | -8457 
8526 | -8549 
8616 *8638 
8703 | “8725 
“8788 *8809 
"8870 | 8890 
“8949, | -8969 
9026 | 9044 
9100 | “9118 
“9171 | -9188 
9239 | +9256 
‘g304 | 9920 
‘9367 9382 
9426 | “9441 
9483 | -9497 
‘9537 “9650 
9588 | -9600 
| 9636 | -9648 
| “9681 | 9692 
i 9724 “9734 
9763 “9772 
9799 | -9808 
9832 | -9840 
4 “9863 | -9870 
“5842 "9890 | -9896 
“5983S “9914 “9920 
“6122 “9936 | -9940 
6259 “9954 | -9958 
“6394 9969 “9972, 
“6528 “9981 | -9984 
6659 9988 “9990 9992 
6788 9905 9996 “9998 
2 “6915, 9999 “99991-0000 
“6978 “T009 “7040 ! 
“TLOZ “T132 “7163, 









































sive of any ven anos the length ofthe permenlicalaropposita the given angle {na 
langle which contains he given angle divide! by the length of the hypotenuse, 
sonstructed on the prineiple that the hypotenuse Ls alwaya equal to unity, by which 
tion Is got rid of, ns ths denominator may be left out. ‘Tass 


= Perpendicular _ } 
Sin 307  ypotenuse “1 = 


3u2 








2 
& 
5 
$ 


i| 


| 


USEFUL TO THE MICROSCOPIST 


Bisulphide of Carbon . 
Quinidine . 

Zircon. . 
Carbonate of Lead 
Borate of Lead . 
Sulphur (melted) 
Phosphorus. 
Realgar (artificial) 
Diamond (ep. gr. $4). 
Chromate of 


Crown. 

Plate . 

Flint 

Dense Flint 

Extra Dense Flint 
Boro-silicate Crown 
Phosphate Crown. 
Barium Silicate Crown 
Boro-silicate Flint 
Borate Flint 


Barium Phosphate Crown | 
Very heavy Silicate Flint . 


Glass of Antimony 


it Sp Sh oti 
(approximately) # > 
Se eo 


Glass 





‘als 





1030 APPENDICES AND TABLES 


APPENDIX C 


TABLE OF ENGLISH MEASURES AND WEIGHTS, 
METRICAL EQUIVALENTS 


‘The following are calculated from the values of the 
by Col. Clarke, BE. (1867), as equal to 89870482 inches 
of a cubic foot of water at 62° F. found by Mr. H. J. Chi 
equal to 62:278601 Ib. avoirdupois. 





Leyeta 
Inch . . cose ee. 258998 C 
Foot =12 inches woe eee ee 58048797 T 
Yard=8 feet... .... . = 91489M 
Fathom=2 yards . . . . . . =1:92878 
Pole=5} yards... . . . . =6:02015M 
Chain=4'poles |... . . - =201166D 
Furlong=10 chains. . . . . . =201166H 
Mile=8 furlongs. . . . . . . =1°60988 EK 
SuPERFICIES 
SquareInch . . . . . . = 645148 Square 
= +00645 Milliar: 


» Root =144 Square Inches= 92001 
» Yard-9 ,, Feet = 886112 Millian 
= 88611 Contiar 











Perch=80} ,, Yards = 2:52924 Deciar 
Rood=40 Perches . . = 10-11696 Ares. 
Acre=4 Roods . . . =4046784 ,, 
Voiume 
Cubic Inch . i = 
» Foot. 728 Cubic Inches= 2°88161 
» Yard. » Fett = 7 
Capacity 
Apothecaries’ 
Minim, mq... = 05920 Cubic Centimetre or Mi 
» £3 = 60 z Centimetres or M 
Ounce, £3 =8 f 5= 7 = 
Pint,O . =20 = =56 
Gallon,C = 80 = 454667 ,, Decimetres, Mill 
Imperi 
Gill. . . . . . =142:08854 Cubic Centimetres = 1: 
Pint. . =4 gills =56895415 ,, =5 
” Decimetre, Mill 
» Decimetres, Mill 





B85 . ” 
Bushel| =4pecks = 8:68788 Decalitres. 
Quarter =8bushels= 2-90986 Hectolitres. 


USEFUL TO THE MICROSCOPIST 1031 


Waicet 
Apothecaries’ 
Grain, gr... . . . . . . =648799 Centigrammes. 
Scruple,9. . . . = 20 gr.=1-29760 Gramme. 
gues 228. eee 
ce %. . = B3= gr. = 811424 Decagrammes: 
Pound, lb. | =12 3=5760 gr. =8°78708 Hectogrammes. 
Avoirdupois 
yrachm, dr. . . . . , = 2784875 gr.= 1-77406 Gramme. 
yance,oz. . . . =16dr.= 487-5 gr.= 2'88850 Decagrammes. 
‘ound, Ib. . . . =160z.= 7000 gr.= 4°54160 Hectogrammes, 
marter,qr.. . . =281b.. . . . . =12/71647 Kilogrammes. 
{undredweight, ewt.= 4 qr. § = 1:01782 Centner. 
ton. wwe « = 20cwt . . « . = 101782 Tonneau. 





1 Ib. Avoirdupois= 822857 Ib. Troy or Apothecaries’. 
1 1b. Troy or Apothecaries’ = 1:21527 1b. Avoirdupois. 





4BLE OF METRIO MEASURES AND WEIGHTS, WITH THEIR 
ENGLISH EQUIVALENTS 


‘The metre was originally intended to be the ryadyausth part of the dis- 
ce from the pole of the earth to the equator, measured along a certain 


ridian, but owing to an error its 1 is too short, The metre is 
tefore the length of a definite stan: in Paris. 
Lenera 
Micron, ie. p . = yo Millimetre . . = -00008987 Inch, 
Millimetre. . = fy Centimetre. . = “08987 ,, 
Centimetre | | = yy Decimetre . . = ‘89870 
Decimetre . . = yy Metre. . . . =8-98704 Inches. 
Metre . . . = Unit. . . . . . =8'28087 Feet. 
= 1-098628 Yard. 
Decametre . . =10 Metres. . . « “98840 Pole. 





Heetometre. | =10 Decametres . . =4-97101 Chains. 
Kilometre | | =10 Hectometres . . =4:97101 Furlongs. 
= 6218767 Statute Mile. 


ana SUPERFICIES 


1084, Decimetres - 107641 8q. Ft.= 155-00 8q, In. 
» Metre = _1-19601 Square Yard. 

> Zo », Metres = 1196011 ,, Yards, 

1 =1 $} Decametre =119°60115 4, oy 

: =1 |) Hectometre= 247110 Acres, 





VoLuME 


Millistere . . =1 Cubic Decimetre = 61-02587 Cubic Inches, 
Centistere =10 ,, Decimetres =610-25868 ,, 





Decistere . . =100,, » === «BOB156 y, Feet, 
Btere=Unit | =1 |, Metre = 130708 |, Yard? 
Decastere . . =10 ,, Metres = 1807085 ,, Yards. 


Hectostere. . =10 Decasteres = 180-79854,, te 





IO. GO NF 


10 


OONVERSION OF BRITISH AND METRIC MEASURES 


ina. 
000039 
000079 
000118 
000157 
000197 
000238 
000278 
“00315 
000354 
000394 


000433 
000473, 
000512 
"000551 
“000591 


000709 
000748 
W00787 


USEFUL TO THE MICROSCOPIST 





99 


ns, 
S-937043 
7974086 
1811130 
15-748173 
19-685316 
23633969 
559303 
“496348 








LINEAL 
Micromillimetres $0. into Inches fo. 
mm. ins. 
1 089370 
2 078741 
3 8111 
4 1187483, 
& “196853 
6 336233 
z 376593, 
8 314963 
9 384334 
10 (10m) “393704 
u “433075 
32 “472445 
18 “bl1si6 
“4 “561186 
15 *890586 
16 639037 
a7 209297 
18 708668 
19 748038 
20 (30m) “787409 
a1 936779 
22 266160 
23 905620 
24 244890 
25 904961 
26 1033631 
27 1-063008 
a8 1-103872 
29 ri74s 
80 (3m) 1181118 
an 1230483 
39 1-359664 
33 1909234 
34 1-338595 
35 1.377965 
36 1417336 
37 1456706 
38 1496076 
39 1836447 
40 (40cm) 1674817 
“1 1614188 
42 1-53858 
“a 1693039 
“ 1733399 
45 1771669 
46 1811040 
47 1850410 
48 1889781 
pr 1.929181 
50 (6m.) 1-968532 
dectm, 

q 

2 

3 

4 

rf 

6 

7 

& 

9 

10 





35 
(=1 metre) 39370483 


= 3280860 ft, 
= 1008638 yd. 





1033 


ing, 

2007802 
2047963 
3088633 
3°136003 
9:165374 
3204744 
374115 
3289485 
3399855 
936226 


3401696 
3440967 
9°480337 
3519708: 
3°559078 
3°596449 
se37819 
a77189 
3716860 
3°765980 


2°795301 
4834671 
rer04 
nmr 
9°963788 
3°909183 
3-001528 
3070804 
3110264 
3149685 


3189005 
3238375 
8267748 





3700830 
3740191 
3770561 
salg0ss 
3-858303 
3907673 
100 (10 om. = 1 deoim.) 





USEFUL TO THE MICROSCOPIST 1035 


1 equivalent of the metre is 89:87079 inches, and of the kilo- 
432'84874 grains. In the above tables Colonel Clarke’s 
89:370482 inches in 1867 have been adopted as being the 
te. In 1882 the metre was again measured by Rogers, who 
al to 89°37027 inches. sha athe ‘Vong 

can be more accurately compared either lengths or 
The actual weight of the standard kilogramme in Paris is 
grains. Its theoretical value, viz. the weight of a cubic deci- 
er, according to Colonel Clarke and Mr. Chaney, is 15418-08110 
Rogers’ value of the metre were used it would be a trifle lesa. 
nme is some 194 grains heavier than theoretically it ought to 
itre, a vessel holding a kilogramme of water, has therefore a 
city than a cubic decimetre. 


en necessary in the examination of a photo-micrograph of 
other periodic structures to determine at what rate per inch 
the structure is in the original object, the amplification of the 
graph being known. 

: In a photo-micrograph of @ diatom amplified 785 diams. 
be counted in “8 of an inch. At what rate per inch is the 
the diatom ? 


magnifying power x number counted , 
space counted : 
785 x12 . 
8 ie = 29.400 per inch. 


> answer is required in rate per mm., the space in which 
is counted being in inches as before, then, because 1 inch 
om. 





785 x 12 

‘B inch x 25:89977 

ose a rule divided in mm. is used to determine the space in 

umber on the photo-micrograph is counted, and the rate per 

tired: if twelve dote ean be counted in 7 mm. then, because 
187 inch, 





=1157°5 per mm. 


= 29,400 per inch. 








USEFUL TO THE MICROSCOPIST 1037 


APPENDIX E 
OPTICAL FORMULE 









©, the optical centre of a lens: Let A and B be the vertices, let 
of the curve A=r, and that of B=s, ¢= thickness of the lens 
refractive index. Then 


Ate tts woe?! 2 og @ 
r-3' T-8 Me So hed oe 


explaining the method of treating the signs: First, it should 
‘ly noticed that all curves which are convex to the left hand 
e radii, and those turned the other way negative radii. 
 biconvex let r= 2, 2= —8, and f=1; then by (i) 

fet. 8 32, Bowne. =F. -8, 
g-(-8) 2+8 5 2=(-8) 248° 6 

int O is measured, therefore, to the right hand from A, and to 
B. Ins plano-concave let r= —2,8=00, and ¢=1; then 


AC= 





-2x1_o. ~wxl lwo _ ; 
AG=—*) -05 BCs “> = 1... @ 
therefore eoincident with A. 

nodal points D and E may be found thus: 











ap=1,*!. gre}, * . @ 
ple pi Pas 
ple: Ine meniscus r= —8,6= -2,¢=},andp 
-s.i 8 =f 
Ap - 2 peg By) Ee Bs 8 5 8 hg 
- $° 8-2) ~ 8° Bee” 8 Tl 84 We 


2 
Dis measured 4 inch to the right from A. 
1 


oo i) 





x2 1 
3° =3s8 "3:27 8 
2 
EB is mensured } inch to the right from B. 
If the meniscus iitimaed round so that its convexities face the left 
bund, r=2, »=8, t= Bags 
1 


pecde gee @ 


ae 


1038 APPENDICES AND TABLES 


formule (ii) are approximations, sufficiently accurate for general practical 
purposes, but in cases of importance the following, longer but more 
accurate, formule should be used : 


t 








ap~-__*# 3; BE= 
#(r—8)—t(-1) # 
Plano-eonvex Lens.—Let f=the principal focal point and y=the 
semi-aperture; then if parallel rays are incident on A, the plane side of 
the lens, r= co , and by (ii) BE=0. The nodal point is therefore at the 
vertex B, and the focal length 





Bi As Ef=Bf. . 2... . Gv) 
Tho spherical aberration ee 
age =} fa) i a) 
Thus when » =%, 
Bfa SRB Me os. as) ipa sean 
f 


If the parallel rays are incident on the convex side A, #=2, 
BE-= —° (ii), and the focal length 
ry 





rt i i? A 
Bho Wi Efe Ty. + Oui 
The spherical! aberration . 
aye - Me eee ee a (viii) 
When p= 1516 (plate glass) : 
afe Fe Stns cei wit ae Seek oh SEG: 
When p = 1-62 (flint glass) ; 
bf= 80424 kk vil 
Lf 7 (viii) 
To find the radius of a plano-convex lens, the ref. index and focus 
Ef being given: 
raf. ee evi) 
"4 To find the radius of a plano-convex lens, the ref. index, the thickness, 
f and the focus Bf being given : : 
' roboDusso ee 


A plano-concave lens follows a plano-convex; f will be negative, 
which shows that the focus is virtual. Concaves being thin, ¢ is usually 


neglected. 
‘Equi-convex and equi-concave generally : 


aed i 
Bhogrp ct Gs) 


Equi-convex more accurately : 


1 Heath's Geometrical Opttcs, 1887. 


USEFUL TO THE MICROSCOPIST 1039 


r t 
: Bio wat) 2qe) 20) 
Spherical ' aberration 4u"(u=1) eg 
FA neste of chara ee ok. DO Pa i 
Ts | a 
In an equi-convex Ions when n= *, 
apa 10 beet Saas ge ten sth) 


To find the radius of either an equi-convex or equi-concave lens, 
Benerally, the ref. index and the focus Bf being given: 


r=2@-Nf ss... ee. Gs) 


To find the radius of an equi-convex lens, the ref. index, the thickness, 
aad the focus Bf being given : 


pe UD LAF essed | 


pel » 2G} 
Bi-convex and bi-eoneave, generally : 
_1 ors i 
re TC) 
Bi-convex, generally : 
1 ra _1 at i 
Le a) 
‘The same when about equi-convex, generally : 
Bye 1, 78 sg eee Gly) 


“pol'e-r 2+) * 
Bi-concave ¢ may be neglected Bf=E f practically. 
Bi-convex more accurately, and converging and diverging menisci : 


{u-ni-r} 


Bye Lo 
@=D{r- we} 


When the light is travelling from right to left 
t 
r{u-n ute } 


Serene eee a (av) 
@-) roam} 


Spherical aberration : 
weds mtd_yl_ly sy? ‘ 
; of- Tete t( f ale; ‘) } yo eM 
Example: Letr=2, #= 8, ¢=1, and n=3; then by (xv) 


1 Heath's Geometrical Optics, 1887. 


1 





1040 APPENDICES AND TABLES 


— ut ch ai 





8 5 
pyaar | 
pre dae: 
2°38 a 
Similarly af=-23 
By (xiv) py=B-t aa}. 
7 gna 7, 
‘Therefore (xiv) and (xv) are respectively 77 and 76 


The following is an example worthy of se ee 


r-actand > (y—1)4, 
f 


‘Thus let 7255, 0-5, t=1,p=8, 
7-8-3 1h is 

Then by (xv) BI rT) * 4 = —810. 
2\2 8 i2 


It will be observed that, although this meniscus is thickest in the 
middle, it hae, however, a large negative focus. 

The nodal points of a sphere are at its centre. 

‘The focus of a sphere, measured from the centre : 


Bsa tt yori tt + Gx 
‘The focus of a sphere measured from its surface : 

7 (2—p) ‘ 

en 


‘The focus of a hemisphere measured from the vertex, the light being 
incident on the convex surface: 


Bre 7 oe 
Fg i) 

But when the light is incident on the plane surface 
-s ‘ 
Bhat wD 


When » = 1'6 the focus of a sphere measured from the surface = 4 the 


ius, 
The focus of a hemisphere measured from the plane side =1} the 
radius, and when measured from the convex side the focus = 2 radii. 


In a cylindrical lens the nodal points cross over. 
To find the radii r and s of a crossed lens of minimum aberration for 


parallel rays: 


USEFUL TO THE MICROSCOPIST 1041 





For plate glass p=1°516; r="6985f; and e= —8°044f; (xviii) 
aga — 1008 ¥ Boca hy aii ie, 0 OD 
For flint glass p= 1:62; r=-668/f; and #= —12-06/; (xviii) 
2 
af = 108 ee Gui) 


Critical angle.—Let 6 be the critical angle for » ray passing out of a 
nser medium into a rarer one. 


Then oe) 


‘When. p= 1:888, 6=48° 864’; une » O=41° 48}; p= 152 6=41° BY’; 
= 1-62, 6 = 88° 7’. 

Let f be the principal focus, and p=the distance from the object to 
8 optical centre of the lens, p’=the distance from the optical centre of 
e lens to the conjugate image. 

fob 


Then p= H a 
P P+?’ 
Let v be the distance from the object to f, and w be the distance from 


on the other side of the lens to the conjugate image. 
‘Then 








+e (x) 





v=p-fi w=p'—f; p=urf; p'=w+f; and vw=f?; o£; 
a ec) 
If o be the size of the object and ¢ the size of its conjugate image 
‘ oR'-f), 





t 


of; 3 fa th alk ren )) 

Examples: With an objective of }-nch focus it is required to project 
1 image of a diatom ‘08 long, so that it may be 1°5 inch on the screen, 
hat must be the distance of the screen from the optical centre of the lens? 





Therefore p’= 253 inches, the distance required. . . . . . (xxii) 


Conversely, if the image of a diatom projected by a }-inch objective 
reasures 2 inches on the screen at 40} inches from the optic centre 
‘hat is the size of the diatom ? 





see ee (xxii) 


ae size of the diatom required. 
3x 





USEFUL TO THE MICROSCOPIST 1043 


mmple will be of interest, Let parallel rays fall on the convex face of 
m field lens of a Huyghenian eyepiece; find their focus. 
Let f, the focus of the field lens=8, and that of the eye lens f'=1; 


=8 and the distance between the surfaces, that is BA’,=18; t the 


ckness of the field Jens = 5 and ¢ that of the eye Jens= 3; AD=0 


); BE=-—!= —+ (ii), Similarly A’D’=0; B’E’= -f--$.@: 


3 10 
=EB+BA’=2+18=2, Now 





o’=E'-, 21 = see ee (sav 
8x1 8 sit 
area att rer ee ¢ = 35) ) 


‘We see, therefore, that the equivalent focus is 1} inch, but the 
mincipal point, G’, from which the focus is measured is 1 inch to the left. 
fom E’; therefore the focal point is } inch to the right from E’. Now as 
® is 1, inch to the left of B’, the plane surface of the eye lens, it follows 
BME ihe focal point, is yy inch to the right of the plane surface of the 
A) 





This explains ‘the microscope objective of 10-ft. focus.’ 
The equivalent focus of the objective was 10 ft., but the nodal point, 
¥, from which that focus was measured was 9 ft. 11} inches from the 
Yective, which would give 4 inch as the working distance of the lens. 
objective in question has a double convex back lens and a plano- 
™meave front; a small decrease in the distance between the lenses, such 
‘ @yby inch, has the effect of causing the principal point, G’, to recede many 
®t, and of causing a great increase in the equivalent focus. 

With regard to the optical tube length, the position of the principal 
‘ints of acombination plays an important part. Suppose the Huyghenian 
“epiece, in the preceding example, was mounted as an objective; the 
Ibe length would have to be measured from the right-hand principal 
"int of the eyepiece, wherever that might be, to the left-hand principal 
¥int of the objective, which in the example before us is 


GaP 20248. ps8 ss oe 5k lexi 





G is therefore measured 8 inches to the left from the point D; D is, 
+ we have seen, coincident with A, the convex vertex of the field lens. 
D anyone measuring the tube length from the field lens, which is the 
aeterior lens of our supposed objective, or from the middle of the 
ambination, would be 8 or 4 inches in error. 
-The importance of this cannot be over-estimated, as the optical tube 
has a direct bearing on the power. If Q=the distance of vision 
‘gy 10 inches), M =the magnifying power, F = the equivalent focus of the 
Vepiece, F’ =the equivalent focus of the objective, O=the optical tube 
Xgth measured in the manner indicated above; then 


M= cose ee oe e © (xxviii) 





If¢ =the focal length of the entire microscope, N.A.=the numericat 
rture, and «=the diameter of the eye-spot, then 
9 FF , 
oN Oo” eee ee ee (exix) 
Journal R.M.S. 
3x2 





USEFUL TO THE MICROSCOPIST 1045 


aro a= ~8 (xxxil); om gis (axxvi); wt aren MA: 

Py 20 

= iz fc = 3 

f=2F (xxiii); therefore 0 Pad 
= Fw _ _5 

aps eee Ho aD 

‘This is half the aberration of an equi-conver lens (fig. 1) of the same 
bboal length as the combination where 

separa a og r 

af ee ee GD 

If the front lens of the combination be turned round so that its conver 

rarface faces the incident light the aberration is 


a oe 
éF ee ee aD 


ro) 
wr half what it was before (fig. 6). 
is is nearly a third of the aberration of » plano-convex in the best 
position (fig. 2), which is 7 
_vy 22 
Fane we eee Coil 
‘The following figures pictorially illustrate spherical aberration in 
tingle lenses and in various combinations of two plano-convex lenses, all 
ing the same focus, F, the same aperture, and the same refractive 
index, 3. The dot nearer the lens is the focal point for the marginal, and 
that farther away the focal point for the central rays; the distance 
between the dots is the spherical aberration 8 F 


Fro. 1. Fro. 2. Fis. 5. 
Fig. 1. An equi-conver,7=F; 
8Fe= -10 f= 178 6 1 we ew (xi) 


Fig. 2. A plano-convex, reas 


oF= -110 f= —11.. 0. | (viii) 


Fig. 8. A crossed convex, rh F; = -k F (aviii); 


aFH 101 f= 1) a 37) 


Fig. 7. A combination of two planos with their convex faces in con- 
iact, the focus f of the first lens being equal to /’, that of the second. 


Phe foous of the combination F=/ . BOR wo) ea ade ed eR 


oF= —-s93%'= --067.. 0... + Ql) 


¥F 
Fig. 4. The same, only 2f=/"; 


% dy Oe ye Oe -reu 168 6 1 eo ee (xl) 

















USEFUL TO THE MICROSCOPIST 1047 


An excellent combination, suitable for a bull’s-eye, can be made of an 
Panatic meniscus and a plano-convex of flint, or a crossed plate lens. 

e following are the radii of some examples. A doublet of plate glass 
==1516. 

1st lens, a meniscus, diam. 1:7”; r= +°964”; +1875". 

2nd lens, bi-convex crossed, diam. 21”; r’= +1:816”; #’= —12-07”. 

The flatter side of the crossed lens to face the meniscus, the distance 
between the lenses 05”, P= 1:6”, P’=2:425”", 83F = —-168”, angle 70°. 

A better combination can be made by substituting a flint plano- 
convex for the second lens, diam. 21” 4 =1-62;r’= +1:88';3F = —-182”. 
‘The aberration is therefore 036” less than before. 

The aberration may be further reduced by adding another meniscus 
and by making all the lenses of flint 4 = 1-62. 

1st lens, a meniscus, diam. 1-65”; r= +°958"; = +1°85. 

2nd lens, a meniscus having its concave side facing the convex side 
of the first lens; diam. 20”; r’= +1°67”; 8’= +2:55”. 

‘The third lens is a plano-convex, with its plane side facing the 
convex side of the second meniscus; diam. 2:1”; r”= +2914”; P=1'55; 
3F= —-0226; angle 70°. 

The aberration is therefore ‘145’ less than that of the first example. 
‘The distance between the lenses is 05” as before. 

To find the radii r and s of a lens which will refract light from a point 
Pto point p’ with minimum aberration. 























K= P+?) | | (alii); 2 Serr 
@-)y cu f pty’ =) 
7 2 (u+2) p i 
‘Gas pk-tG@en we Fee GD 
r 
tar ee 
Let B be the coefficient of in formule v, viii, xi, and xvi, then for 
parallel rays in each particular case the lateral aberration = 8 % . (avi) 
Diameter of least circle of aberration = 38%, ee eee (xvii) 
Distance of least circle of aberration from focus = ~feu . (xlviii) 
‘When the rays are not parallel 
alvi=op'y — (xlvi)=}op'y? (atvitt) = ~B apy" 
It is interesting to note that Y=2(u-1)t. ss. ee (alix) 
y 
‘Therefore, when p Ynt 


To find m, the magnifying power of simple lenses or magnifying 
glasses. Lot d be the least distance of distinct vision apart from the lens, 
and f be the principal or solar focus of the lens. Then 


meals thw Six aute Gy a 


It may be of interest to note that formula (xx) on this page may be used. 
to determine the focus of spectacles required to bring the abnormal focus 





USEFUL TO THE MICROSCOPIST 1049 


Formula relating to Prisms 


Let c= the refracting angle of the prism, ¢ the angle of incidence on 
she first surface, ¢’ the angle of refraction at the first surface, y the angle 
f incidence in the prism at the second surface, and w’ the angle of re- 

‘ion on emergence; then the total deviation 
D=G4y'-15 Pryor 2... . Gi) 
When the ray passes through the prism symmetrically the deviation 
Minato minimum: ¢=y', $= m5, and 7 
_¢«+D 
sin’) 
Be 





»y which formula the refractive indices of media can be found, because 
‘oth : and D are capable of accurate measurement. 


sin 


Formula relating to Conic Sections 
Ellipse.—Let A= major aris; a= ininor axis, Then 


A-v 
2 





Focus = 


Parabola.—Let A= height; a= 3 base. Then 








Focus = -%, Le Qi) 

Hyperbola.— Let A = major axis; 
Foeus = “At#at=A srccei Oige. ne OR 
Works consulted:—Coddington, Camb. 1880; Parkinson, Camb.; ‘Ency- 
slopedia Britannica’ ;‘ Journal R.M.S.’; Hoath, Camb, 1887, &c. It will be 





seen that several of the formule have been entirely reset, while some 
appear now for the first time. 





1050 APPENDICES AND TABLES 


APPENDIX F 


EXAMPLES USEFUL TO THE MICROSCOPIST 


Square # inch . . . = 10-08045 square millimetres. 
wa om +e + = 645148, ” 
oe = eBORL i 
Doe oe ee = 08451 is 

= 645148 # » 
woo on se = LS, e 


Square centimetre . 
» — miillimetre 
» 0p... 
» Wp... 
i Wipe se) esp = 00155 » on 


Multiples of the above may be found by multiplying the valuet 
dy the square of the multiplier. 

Thus, square ;t; inch =; x4; the square of 4-4 x 4-16, and6 
x 16 = 108-2268 square millimetres, the answer required. 


Cubie } inch + + = 82:00508 cubic millimetres. 
we . 1688662 ,, ” 

948300 ,, ” 

2. = 01688 | < 

+. =1688662 


=15'5008 square 3 inch 
5003, re 


” Tyson 









Cubic centimetre. . . . . =61-02587 cubic 3; inch 
» 6millimetre. |; | | 6102587. qty wn 
» 0p... 2... =6102087° «3, ste 

= 061025 mow 
yee ee ee ee = 000061025 








Multiples of the above may be found by multiplying the values 
by the cube of the multiplier. 

Thus, 2 cubic millimetres: 2 cubed =2x2«2=8, and 61:02. 
= 488-20296 cubic ;!; inch, the answer required. 


Areas of Circles 
4 inch diameter=122718 sq. jinch= 79171 6q- millim 
” * = °78539816 , 5» 50670, ” 





wo SAAD ey 
* = 778540 ssw 


“78540 ads 





*78589816 5q. sq. 3k 
854-0 # os 
18°54 * non 

“7854 + non 


USEFUL TO THE MICROSCOPIST 1o5r 


ultiples of any of the above may be obtained in the same manner as 

\ preceding example. 

wus, if the diameter of the circle ~ =f; inch, then the square of 8 being 
“7854 x 9 = 7-0686 aq. ;35 inch cod *05067 x 9 =-45608 eq. millimetre, 
le areas required. 





Volumes of Spheres 
. diameter . =1-02266 enbie 3; inch= 16-758 cubic millimetres. 
” ” . = 62860 » = 8500 , » 
” ” + = 80801, » = 4965 4, ” 
ym 9 = 152860 G5 =| “00858 ” 
» ow + = 152860 ates » = 858000, 
wdiam.. 2. = "52860 cubic mm. = 81-958 cubic po inch. 

zi 1600-0 »  # =81958 » S05» 





528°60 » 9» & 08195, 
oe = 52360, nm = 00008195 , 


ultiples of any of the above follow the preceding example of cubic 
ares. ‘Thus, if the diameter of the sphere = 80 y, then the oube of 8 
27 and 5236 x 27 = 14187-2 cubic » and ‘08195 x 27 = -86265 oubio r45 
are the volumes required. 





1052 APPENDICES AND TABLES 


APPENDIX G 
USEFUL NUMBERS AND FORMU1 


Paris line = 088818788 inch. 

Statute mile = 5280 ft. = 1609-380 metres. 

Geographical mile = 6082-66 ft. = 1858'978 metres. 

Nautical mile = 6080 ft. = 1858-167 metres. 

Cubic foot of water weighs 62-2786 Ib. avoirdupois | 

Cubic inch of water weighs 252-286 grs. at 62° Fah 

Gallon of water weighs 10 Ib. avoirdupois at 62° Fe 

1 gallon = 277-46288 cubic inches. 

Cubic foot of sea water weighs 68-968 Ib. 

‘Weight of sea water = 1-027 weight of fresh water. 

1 inch of rainfall = 100 tons per acre. 

Pressure of water in lb. per sq. inch = °488 head of 

‘Expansion of water between 82° Fahr. and 212° Fa 

Dip of horizon in nautical miles = 1-28 /height. 

Marks on hand lead line for sea soundings 1, 2, 
and 8 tags of leather respectively; 5 and 15 fathom 
17 fathoms red rag; 10 fathoms Teather with hole in it 
rag; 20 fathoms 2 knots; 80 fathoms 8 knots &. Aé 
at intermediate 5 fathoms after 20 fathoms—viz.. at 25. 

Pressure of wind in Ib. per sq. foot = 0-002288 (\ 
second)’, 





Areas and Volumes. 
Area of triangle = base x } perpendicular. 
Volume of wedge = area of base x ¢ perpendicular h 
‘Volume of cone or pyramid = ares of base x 4 perpe 
Surface of side of cone = circumference of base x } 1 
Area of parabola = base x ¢ height. 
Velocity of light = 187,272 statute miles per second. 


‘Wave-length of yellow light = _ inch. 
Number of vibrations per second 598,276,600,000,0 


Falling Bodies. 


8, space fallen in feet; V, velocity in fect per secon 
in seconds. 


8-2! Va Vtg VE= 8-005. 
25 V-ViG + VE= 8005, 


Arithmetical Progression 


A, first term; B, last term; 8, sum; d, difference 
number of terms. 


1 Latest determinations by Young and Forbes with Fi: 


USEFUL TO THE MICROSCOPIST 1053 


A=B-d(n-1), B=A+d(n-1). S=(A+B) ee 





Geometrical Progression 
m, multiplier or divisor. 

B na Bm-A 

A=» B=mA®-»,  S= a ad 


Properties of Circles and Spheres dc. 


m . . =8914159265858079 + loge . =0-4971499 
w= 986962 fe, = 1-77945 2 = 81881 
1 1 
+. = lois2 Lm -ses19 
m Ve 
3 + + =752860 /%=1-41401 /2%y = 8:02496 


Circumference, C. Area, A. Radius, r. Diameter, d. Volume, V. 
jurface, 8. 
Ca2nr-nd, A=nr, Sand’, v-7f, a=, 
7 
Area of sector of circle - 128tees in are x area of circle 
860 + 


Length of aro = number of degrees x -017458 7. 
Unit of circular measure = 57°-29578. 

Bide of'square of equal ares to a circle = 7 Vm. 
Side of inscribed square = 7 /2 
‘Area of ellipse = } major axis x } minor axis x m. 
Volume of ellipsoid = major axis x (minor a: 





om 


Number of Threads in Whitworth's Standard Screws 


Sizes yy - - . «+ « Noofthreads 48 
4 gi ah GRY be # 40 
” eB. gL osty aie if 20 
wie Mee See nae ee Se * 16 
or ” 12 


Convenient Approximations for rapid Caleulations 
6 knots =7 miles, more correctly 13 knots =165 miles. 








5 kilometres =38 ,, ” ” 60 kilometres =81 ,, 
lmetre =8f.8lin.,,  ,, 64 metres = 70 yards, 
5centimetres=2 inches ,, ” 88 centimetres = 18 inches, 
8 millimetres =} inch » 5 millimetres =} inch. 


1 pole =5 metres; 1 furlong =2 hectometres. 

5 w=sdyo inch; yoy inch=4 mm.; rooguo inch =} p. 

2 are=289 sq. yds.; 1 rood=10 are; 2 acres=81 are; 100 hectare 
=247 acres; 8 cubic yards = 23 decisteres; 1 decastere = 18 cubic yards; 
} millilitres = 84 m (minims); 2 decilitres=7 f 3 (ounces); 4 litres 





“1054 APPENDICES AND TABLES USEFUL TO THE MICROSCO 


=7 pints (imperial) ; 2 grammes=81 grains; 4 grammes=1 3 (dra 
(epothecaries) 7 grammes =4 dr. (drachms) (avoirdupois). 
Idlogrammes = 11 Ib. (avoirdupois). 
50 kilogrammes = 1 centner =1 ewt. 


Nobert's 19 Band Test Plate 


Band Lines per inch Band Lines per ir 
2 11259°5 16 90076°1 
5 3778-5 | 19 11259571 
10 61927°3 | 


Difference between each band = 5629-75. 


Nobert's last 20 Band Test Plate 


Band Lines per inch Band _Lines per ir 
1 11259°5 15 168892:7 
5 56297-6 20 225190°3. 
10 112595:1 


Difference between each band = 11259°5. 


Convenient Formula for Lantern Projection or Enlargement ar 
| Reduction. 


Let D be the distance of the screen, and d the distance of the o 
from the optical centre of the lens, F the equivalent focus of the ler 
the magnifying power or ‘ number of times’ for enlargement or reduc 
then— 

D-F, 
D=F(M+1); d= Fei ne F pai M-?7F; 

Example : It is required to project by a lens of 6 inches equiv: 
focus a slide having a 3-inch mask so that it may give a 10-ft. disc, ' 
must be the distance of the screen? Here M the magnification wi, 
40 times. D=F (M+1)=6 (40 +1) = 246 inches = 20} feet. 

Note, in a double combination the optical centre may be assume 
be half way between the lenses. To reduce, interchange the object anc 
screen, 


INDEX 


ABB 
A 


of), his compensation eye-pieco, 
; binocular eye-piece, 103 ; 
copie eye-piece, 103; achromatic 
ser, 212, 256-259, 829; chro- 
condenser, 212, 256, 267 ; camera. 
237; apertometer, 255, 887; 
ser, ‘iris-diaphragm fitted to, 
diffraction theory and homo- 
6 immersion, 313, 818; method 
ing object-glasses, 826-388; test 
330, 381; experiments in dif- 
1 phenomena, 376 
aplifying power of lens, 25; on 
eneous immersion, 28; on ‘im- 
rent of optical glass, 81; on 
cation of eye-pieces, 84; on 
‘le of microscopic vision, 48, 44, 
definition of aperture, 45; on 
re, 48 note; on radiation, 57; 
gle of aperture, 60, 61, 62; on 
tion, 63-75; on ‘intercostal 
73; on ‘penetration,’ 62; on 
nplification, 90; on stereoscopic 
90, 93; on ‘aplanatic system,’ 
orthoscopic effect, 95; on Rams- 
sircles, 107; on solid cones of 
2 
on, 19; positive, 21, 809 note; 
ve, 21, 27, 309 note; chromatic, 
herieal, 31, 251, 254, 881; errors 
erical and’ chromatic, corrected 
18, 306 
Isamea, 383 
seis, 686 
1's prism, 344 
on or dioptrical image, 64 
iffraction images due to diffrac- 























of polypes, 786 ; 
1,796; develop- 
4, 798; medusan phase of, BOL 
metra’ ziphicantha, 774; echi- 
yT7T 
‘metrina, 772,776; central capsule 





Act 


Acarina, ongs of, 998-029; anatomy of 
‘988-996; larve of, 988; nymph of, 983; 
integument of, 984; legs of, 984; eyes. 
of, 985; classification of, 986 

Accommodation, of the eye, 88 ; depth, 8> 

‘Acetabularia, 493 ; pileus of, 498 

‘Acetic acid, as a test for nuclei, 440 

‘Acheta, 911 

— campestria, eggs of, 929 

Achiya, xodspores of, 494; 
495 ; zolsporanges of, 569 

= prolifera, 498 and note, 494 

Achnanthee, characters of, 545 

‘Achnanthes, trastules of, 517, 544 
of, 518, 544; ‘stauroa’ of, 545; 
ture of frustule, 545 

Achnanthes longipes, 545 

‘Achromatic, comparison of, with chro- 
matic and apochromatic lenses, 815 

— condenser, Abbe’ 

Powell and Lealan 
servation of pycnogo 

— doublet, Fraunhofer 
32a 

— lenses, Charles's, 146; Marzoli’s, 8025. 


Selligue’s, 303 

— objectives, 19,82; Powell & Lealand’s 
dry, 190; Tully’s, 308; Wenham's, 310; 
cover slips for use with, 880 

— oil condenser, Powell & Lealand’s, 267 


Achromatiem, 17, 19, 148; in photo- 





spores of, 






















micrography, 88; rise of, 145; in- 
augurated, 818 ;’ imperfect, causing 
yellowness, 860 

Acineta, 697 


“Acinetiform young’ of Ciliata, 712 note 

Acinetina, 696; food of, 697 

* Acorn’ monad, 684 

‘Acorn-shells,’ 891 

Actinia, reproduction from fragments, 
787, 801 

— candida, thresd-cells of, 808 

— crassicornis, thread-celis of, 808 

Actinocyelus, 618, 539, 550 

‘Actinomma inerme, 774, 776 

‘Actinophrys, 770 

— form of Microgromia, 662 

— sol, 662-665 

Aotinoptychus, 18, 540, 541 


1003 
en 


‘lea, te waren 
Rah aa solvent for rogins, ec. 4415 


“ae, Ml, 808; apines of, imi- 


Aleyon! bled by polyzoan, 832 
boon mle oo een 





INDEX 


ANE 
-Mnemones, 787. See Actroz0a 
“Anemophilous flowers, 647 


“Ansthum graveolens, seeds of, 649 
of incidence, 8; of refraction, 3; 

* of aperture, 61 

-Angles of aperture, air, balsam, oil, 

\. water, 8-31 





light 278 
Angus set, 869 
= ane : ee 
_ mas, 
Anguillula, 869 
“Angalar aperture, 388 


— — of dry objective, 884; of oil immer- | 


sion, 884 
—— of aperture, resolution dependent 
on, 44 
“= — of water immersion, 884 
Angular distribution of ‘rays, 56; grip, 
61; semi-sperture, 77 


foguiifera, characters of, 542 
alin dyes for blue and green stains, 

Animal kingdom, two divisions of, 652 

-Amimaloule cage, 204 

‘Animaloules, 678. See Rovirrna, Infu- 


soria, Razoropa, &e. 
-Animals and plants, differences between, 
1 


461 
“Anisochele of sponges, 788, 784 
<Anisonema, 600 
<Aanrayp, larve of, collecting, 459; ma- 

sina, 673; sppendages of, 978; jaws of, 

; development of, 878 ; eggs of, 874; 
fresh-water, 819 3 luminosity of,'879 ; 

bibliography, 680; ‘liver’ of, 971 
Annual layers in trees, 628 
Annular cell, Weber's, 299 
= ducts of Phanerogams, 628 
— illumination and false images, 862 
— lamination for examining perforated 
“Annelue of sporenge af for, 60 

nolus ge of fern, 601 
Anodon, pearls in, 847; glochidia of, 

857 ; for observation of ciliary motion, 

St4 
Anomia, prismatic layer in, 848 
“anopia (Nemertines) 876 
Anoplophrya circulans, 702 
“Anorthite, 1008 


“Antedon,’ food of, 696 ; pentacrinoid 
larva of, 825,826; pseudembryo of, 827 
Antenne of insects, 911; preparation of, 
913, 918 note 
-Antherid of Vaucheris, 492; of Chara, 
807,508; of Fucacea, 556,657 of Flo, 
idee, 561; of Peronosporea, 587; o! 
Pas tolnaihes eay'508 of ferme’ 602; 
, 598; of ferns, 602; 
tapetal celle in, 608 
-Antherozoids, 467, 470; of Volvoz, 488; 
of Vaucheria, 492 ; of Spharoplea, 
801; of Gedogonium, 608; of Batra: 
um, 504 ; of Chara, 507, 508; 
of , 556; of Fucacec, B58 ; 
of ferns, 608; of Bhisocarpea, 606 














ém’s law for the absorption of | 


| 
{ 


| 


1057 


apa 


Anthers, 644 

Anthony (Dr.) on psendo-trachew of fly's 
proboscis, 915 note 

Anthophysa, 690 

Anthracite coals, 1006 

Antirrhinum majus, seed of, 648 

Apertometer, 174, 888 ; Abbe's, 255, 887 
Tolles’, 883 ; use of, 887 

Aperture, in microscopic objectives, 88, 
48-47, 60-67 ; how obtained, 45; Abbe 
on definition of, 45, 48 note 

— relation of, to power, 82, 88, 811; as- 
gertained “by vertical illumination, 

— angular, 49 note, 58, 888 

— numerical, 49 | note, 76, 888; 
for dry objective 50; for oil immersion, 
50; for water immersion, 50 





| —Dumerical, of Zeiss’s apochromatic 


series of objectives, 818 
— of objective, 882, 338 
— numerical, table of, 84-87 
Apertures, relative, 49 
‘Aphanizomenon, 491 


| Aphanocapsa, 477 





Aphides, wings of, 922, 928 ; agamic re- 
production in, 980 

Aphodius, antennm of, 912 

Apide, 911 

Apis mellifica, mouth-parta of, 918 

Aplanatic system, 20, 28 
‘objective; use of, $1 

=~ cone, 855 

— aperture, 257, 262 

— foci, Lister's discovery, 804 

Apochromatic objectives, 19, 80, 82, 84, 
80, 211; advantages of, 88, "84; 
objective, Zeiss's, 814-890; dry, 815; 
comparison of, with chromatic and 
achromatic lenses, 815; homogeneous 
objectives, value’ of,’in study of 
monads, 687; objective, use with 
various test acales, 900 

— condenser, Powell and Lealand’s, 954 

Apochromatiam, 814 

‘Apocynacea, laticiferous tissue of, 620 

‘Apogamy in ferns, 605 

‘Apospory in ferns, 605 

‘Apotheces of lichens, 578, 579 

‘Apparent creation of structure, 68 

Appendicularia, 885, 841; pi 
ago, Pets eal of 8485 4a; 
‘Haus’ of, 842 

Apple, raphides in bark of, 681 

‘Apposition, growth by, 468 

— mode of growth of starch, 690 

Apus, 888, 886; parthenogenesis of, 888 
note 











— cancriformis, carapace of, 886 

Aquarium microscopes, 219-295 ; Collins's, 
‘991, 929; Schultse’s, 299, 924 

Aquatic microscope, 148 

‘ARACHNIDA, 982 

— eggs of, 929; related to Pycnogonida, 
888 note; reproductive organs of, 985 

Arachnoidiscus, 518, 641 


‘Arachnosphera obligacantha, 774, 776 


3y 





INDEX 


BAC 
rey, 589 . 
in lineola, compared with Cerso- 
580 
1, 586 
fiagellum of, 72; movement of, 
‘gles of, 588, 586; germination 


internal castsof Foraminifera, 


e 
aethod of isolating diatoms, 553 
Cuff's microscope, 140 

yudenta’ microscope, 198; optic 
194 

350 

2, BOL 

balanoides, 891 ; disc of, 802 

on supposed sexual reproduction 
tta, 709 

ngle, 50, 78 

ive index of, 77 

stomates of, 641 

# earth, 771, 774 

i, 627, 683. 

Gregorian telescope, 144 

sment, 215 

lens’ applied to a microscope, 
5,891. See Cirriped 
‘Antedon, 825 

tycetes, 675; as fungus-con- 
Yof lichens, 670 

‘ores of Basidiomycetes, 876; of 
somycetes, 578 


Puceinia, 658; of Basidiomy- 
76 





ia 


site of, 936; hair of, 954; carti- 
ear of, 970 

ua; 672 

a, red blood-corpuscles, 959; 
, 987 

uspermea, 508 

sapermum moniliforme, 504 
eme of, 505 

re scale’ of Lycenide, 899 

ad Lomb’s microscope, 185-188 ; 
al microscopes, 217-220; ‘ labo- 
microscope, 218 ; ‘ University ’ 
11 microscope, 219, 220; neutral 
nera luci 
axillary p: pe of, 984 

+ 987 

1, 717, 718 

alds, 578 

ticroscope for class demonstra- 
195; camera, 284, 285, 280 ; 
¢, 485; bioplasm, 485; glycerin 
Vof preserving, 444 

organic structure, 942 

0.1 microscope, 180, 182; sub- 
2,181, 182; small first-class mi- 
ve, 149; third-class microscope, 
2;'Star’ microscope, 194 ; ‘ eco- 
microscope, 194,196; histological 
ing microscope, 197, 198; port- 
ticroscope, 199, 202; binocular 
ing microscope, 207; rotatory 














tum, 
‘Tight modifier #84; Ne reat ‘illo 
minator, 985; diso-holder, 988; rings 
for locking coarse adjustment, 801 ; 
lamp, 948, 849; achromatic binoculat 
magnifier, 896 ‘note; disc-holder for 
examination of Foraménifera, 770° 
Beck, (B.) on markings of Podura scale, 


Bock-Jackson model, 168 

Bee, hairs of, 904; head of, 908; wing 
of, 918, 922; ating of, 97 

Beeldsnyder’s achromatic objective, 145 

Beetles. See Coleoptera 

Beggiatoa, torm of, 681 

— alba, 588, 584 

Begonia, seeds of, 649 . 

Behrens’ method of analysing minorals, 


1004 

Bell (Jeffrey) on the spines of Cidaris, 
813 

Bell’s cemente, 888, 448 . 

Beneden (Ed. Van), on Gregarina 
gigantea, 674 note; on movement of 

ines, 675 

Bees woe of 441 

Bergh on Flagellata, 689 

‘i eh,’ 551 

Berkaleya, 528 

Bermuda earth, 588, 540 

Beroé, collecting, 459 

= Forskali:, 805 

= ovatus, Eimer on, 806 note 

Bicellaria ciliata, 884 

Bichromate of potash, 480 

mnvex lens, formule relating 40, 91 









julphiee, character of, 641 

Biflagellate monad, 684 

Bignonia, seed of, 648 

Bignoniacea, winged seeds, 648 

Bilocutina, 737 

Binary subdivision of cell, 488, 466 

Binocalar eye-pieon, Tolles', 108; Abbe's; 

108 
Binocular magnifier, Beck's aoiromatic, 
896 note 
Binocular microscope, 61, 97 
— — Riddell’s, 96; Nachet's, 98; stereo- 
3 Stophenson’s, 

3 ‘erecting, 102; 

stereoscopic, for study of opaque ob- 

jects, 105, 107; use of, 105; non- 

atereoscopic, 100; Powell & Lealand’s. 

high-power, 107; portable, Rousselet’s, 

200 ; body’ in Beck's portable, 200 ; 

Stephenson's for dissection, 201, 208, 

844, 895; dinsecting, Beck's, ‘207 ; 

seecirar microscope, 276 












Biol 
Bioplaam, 435 

‘Bipinnaria,’ resemblance of Aotino- 
trocha to, 874 . 





| Bipinnaria asterigera, 891 
Bra 





tiom, 1024 
— of insects, circulation of, 917, 918; 
ot Vertebrate, 968 
relation of size to that 
of bone Incunm, 048 
Nood-corpusclox of Vertebrata, 958 
maxillary  palpus, linkme on, 
BOS 


Spear 
lu ning light, 

“ Blue mould, lid 

Bodo, 475 

Body of the ann 155 


Bombyz, WU 
— mori, eggs ot, 929 
Bonanni's microscope, 14; his hori. 
zontal microscope, 185 ; hin compound 
condensers, 245, 241 





Borax cestings 435 

Bardered pits in the tracheldes of 
conifers, 622, 028 5 
Boscovich on chromatic dispersion, 42 
Botryllians, 838 

Botryllus violaceus, 839 

Botryocystis, 475 

Botrytis bassiana, 673 

Botterill’s growing slides, 280; his 
zolphyte teough, 208 

Bonguot on uniform radiation, 51 

Boworbank on sponge spicules, 783 
note; on structure of mollusan 
shells, 845 

Bowerbankia, gizzard of, $29; stem of, 
892; polyzoarios of, 435 




















Br 
Bryozon, 828, A208 
Bri 
Bubbtes caren ef yeaa, O07? 
riinlatutey palate ol, B54, 858 697; 

idamentint of, 858 ee 
Buchner's 


INDEX 


BUL 
Ball's oye stand, 201 
= item. 
we 
of 684 

775 on mouth of a dois, 690; on 
- Vorticelle, 701 
and on son conjugating vorti- 
eallids, 711 


Datterfiics, wing of, 011 
Butterfly. Boo’ Lapidoptera 


od 


c 
_batterfiy, eye of, 907; number of 


seresicancs of, 881 note 


Cabinet for 454; arrangement of, 


calls of -chambers, 645 
cect ae he ra brittle- 
Oe ean 


Cacumaria crocea, development of, 824 


Caleispongia, spicalon of, 788 
Galeito in sels, 
mips: ic 
Galocanthes indica, ringed seed of, 649 
347 


Saiveentts , bark of, 684 


Calycine monad, 685 
Calyoles of hydroids, 708 
Cal; i Pagel ros 00 
ts lata, 
Cambium, 635 


rocking microtome, 408 
Gamers fucids, 988; Beale's, 284, 985, 
280; Soemmering’s, 284; Wollaston’s, 
884] Amicl's, 280; Banech and Lomb's, 
985; Schréder's, 236; Abe's, 287 
Campani's ‘microscope, 180; éye-piee, 


la, pollen-grain of, 646 
nularia, 794 * 
= gelatinoea, 789 
ae 194; zodphytic stage 
Campbell's differential screw, 158, 198 ; 
‘adapted to the Continental model, 164; 
fine, adjustment, 164, 1065 used in 
‘micrography, 194 
Campylodiscus, 518, 534, 586; move- 
- menta of, 681; stracture of frustule, 
636 








— clypeus, 586 

= spiralis, cyclosis in, 617 

‘Canada balsam, 388 

az Ma Femecrative medion, 441; mode 
1; as’ mounting 





106% 
car 
445; capped jars for, 447; for mounts 
ing 897 


sects, 
Cansl system of Calcarina, 750; of 
‘Polystomella, 753; of Nummulites. 
768 


Canalicali of bone, 948, 945 
Cancellated structure of bone, 944 
Cancer pagurus, skeleton of, 892 
Canna, starch-grains of, 690 
Cannel coals, 1006 


Cannocchiale, 127 











| Capacity of object-glass, 826 
pillaries, 990, 986 


es, 

itium of Myzomycetes, 565 

Capsule, central, of Radiolarsa, 772 

— of moases, 595 ; ra, 858 

— llicious, of Clathrutina, 660 

Carapace of Copepoda, 884; of Clado- 
885 


Carbolic ‘acid: for mounting prepares 
tions, 442 5 for dehy 
disulphide on a elven for oils, 


cap, scales of, 951 

Carpenter (H. P.) on crinoids, 837 note 

Carpenter (W. B.) on stereoscopic vision, 
98; on classification of Foraminifera, 
724; on Eosodn, 768; onalternation of 

generations in Medusa, $01; ‘on the so- 

Exlled excretory pores of Clenophora, 
808 note; on development of Anterion 
887° note; on structure of mollascan 
shells, 845 

Carpenteria, 147; mode of growth com- 
pared with Eorotin, 768 

a_rhaphidodendron, 748 

Carpogone of Floridee, 561; of Ascomy= 
vetes, 572 

of Floridee, 661 
Carrot, seeds of, 649 
Carter (H. J.) om affnity of Carpenteria, 


Cartilage, 970; mounting, 971 
Carum carui, seeds of, 64¢ 
Caryophylita, lamelin'of, 808 
‘Smith, threed-cell of, 808 
Cascarilla, raphides of, 621 
Cassowary, egg-sbell of, 1031 
Castracane, on beaded structure of di- 
atoms, 522; on Pfitzer’s ‘suxospores, 
528, 524; on frustules of 
diatoms, 524; on reproduction of dis- 
toms, 52 diatoms, 528 
Cat, Pacinian corpuscles of, 977 
Catadioptrie, Aluminator, Stephenson's 


Caleta, lars, “"pro-loga’ of, 096;; feet of, 








bai akg Ma, use refractive index, | Catheart’s freezing microtome, 413, 418, 





INDEX 


cHR 


1063 


con 


aatic, comparison of, with achro- ' Cladococous viminalis, 774, 76 


ic and apochromatic lenses, 815 

«ration, 16, 17, 81 

denser, Abbe's, 212, 256, 267, 890; 
‘ell and Loaland’s oil, 258 

rection, test for, 881 

persion, diminished by Huyghens’ 

ctive, 42 

iatophores of Peridinéum, 695; of 

halopods, 866 

tatoplasm, 467 

tic acid as hardening agent, 428 

coccacee, characters of, 477 

177; as gonid of lichen, 579 

gonid of lichen, 579 

, $00; development of, 








rascles in, 961 
“Giacea, 865 
spores of, 555 
z, wings of, 922, 928 
-iacee, pollen-grains of, 646 
tela, 911 
is, spine of, 809, 812 
ularia, mode of formation of spines 
18 
rwaki on decaying cells of Nitella, 
note; on parasitic plasmode in 
‘Ua, 509 note; on reproduction of 
tiluca, 694 
62,968; of Infusoria, 699; use of, 
iiata, 101; of Turbellaria, 870 
“action, 699 
ion on gills of Mollusca, 864 
rement in protophytes, 465 
2, 6¥9-712 ; ciliary action of, 699, 
‘shield’ of, 7005 lorica of, 700; 
phan-layer, 701 ;' trichozysts of, 
ento-paranitic forms, 702; mouth 
02; foot-stalk in, 702 ; impre: \- 
orgaus of, 7023 ‘ey pots’ of, 
food of, 703 ; artificial feeding, 
contractile venicles of, 704; mul- 
sation of, 704 ; colonial forms, 705 ; 
atment ‘of, 707-709; supposed 
al reproduction, 705, 709-711; dis- 
con of, 709; desiccation of, 700; 
agation of, 711; Stein on acineti- 
Young of, 712 note 
‘Infusoria, general structure of, 

















d epithelium, 968 
achiate zouphytes, 829 


lagellata, 605 
of Noctiluca, 691 note 
lectularius, eggs of, 929 


ma, raphides of, 621 

lium arcticum, peristome of, 597 
ria, pollen-grains of, 647 

ious matter, 976 

stion in ascidians, 896, 889 

lood, 978. 

ambient chamber in Orbitolites, 


of Cirripedia, 808 
edia, 801 
vera, 865 





Cladania furcata, 579 

Clara ‘glomerata, 400; cell division 
of, 499, 504 

Cladorhisa inveraa, 784 

Clay and Lachmann on Lieber 
‘kuehnia, 656; on ‘rolling’ movement 
of Amaba, 669 

Clark (James) on Flagellata, 689 

Clastic rocks, 998. 

Clathrulina elegans, 686 

Clausius on emission of light, 54 

Clavelinid, gemmation of, 886; stolons 
of, 888 

Claviceps purpurea, 572 

Clavicornes, antenne of, 911 

Claws, 958, 957 





Clay, 1014 
Cleanliness, importance of, 458 
Clematis, stem of, 627 





“Closed ' bundles, 685 
Closterium, cyclosis in, 510 ; 
of granules’ in, 51 
in, 511; two zygospores in, 518 note; 
zygospore of, 614; form of cell, 515 
‘Clostridia, form of, 881 





| ‘Clothes-moth,’ 938 


Clove-pink, seed of, 648 

“Club-monses,” 606 

Clypeaster, spines of, B18 

Cc oat Tatbodting by, 418 

nna 1005 

Coarse adjustment, ‘ stey diagonal 
rackwork for, 1673 of Ross model, 177; 
‘Wale’s, 185;' arrangements for ‘lock- 
ing,’ 801 

Cobzea, testa of seeds of, 649 

— scandens, pollen-grains of, 646 

Cocetdin, 876, 671 ee 

Coccidium oviforme, 676 

Coccoliths, 672-674; 'in chalk, 1010 


-Cocconeidee, characters of, 544 


Cocconeis, 544 

Cocconema, 528, 545, 551 

= fusidium, 551 

Coccospheres, 672, 674; in chalk, 1010 

Cockchafer, antenne of, $98. See Melo- 
lontha 

‘Cockle’ in wheat, 869 

Cockroach. See Blatta 

Cocoa-nut, 649 

— shell of, 618 

Cocos-wood, 629 

Coddington’Iens, 87 

Codium, 498 

Codosiga umbellata, fission of, 689 ; 
arborescent colonies of, 690 

ContenTenata, 786-807; bibliography of, 











806; nent gastrula-stage of, 652 
— See Zoipnyres 
Caloplana, 806 


Coenosarc, of hydroids, 791, 794 
Canurus, 868 
Cohn, on sexual generation of Yolvoz, 


460; on movements in 490; 
reproduction of lea, 500, 
£01; on affinities of actors, S19 


| 








7 
pressor, 205; Rowland’s reversible, | Ratifera, 716 f 
205; Powell and Lealand’s, 208; De: | Convergence of light, 18 
26 207 Conversion of relied in, spectros #85 
‘prowsariom, | shown by Arachnotiinews, 541 nate 
* Concentric’ bundles, 635 Cones  Inticiferors tinstie of, O20 
Conoeptacles of Fueacev, $50; of Mar-  Convoloulus, cn 









chantia, 591 
Conchifera, shell of, B48 
Goncretionary spheroids, 1021 
Condensrs, 170, 248-263 
— _Kellm 


20 iwift's, for use with 

lariscope, 262; Collins's, with rotat- 
ing sub-stage, 329 

— total aperture of, 956 

— tabular list of, 268 

— achromatic, 104; Abbe's, 212; Powell 
and Lowland’s, 261-254, 268, 267 ; Brow- 
ater on, 249 

— chromatic, Abbe's, 212, 329 

—sub-stage, Stephenson's, 101; com- 
pound, 186 

Gone of light, 170 

Conferva, 486 

Confervacew, 478, 498-600; binary divi- 
sion of, 499; zotspores of, 600; resem- 
blanco of Melovirew to, 537 





INDEX 


con 


white, 961; change of form 
Of connective tissue, 968, 965; 





of en, Bo Sow of, 980 
' Corrected ‘len 
“Garrection sola a 29,60, 990 
tinental, 807 ; 
OEreliah mathod, 508 
crystals, 995 
Gorrosive sublimate, as s preservative 
medium, 448 


Gorynactis Alimanni, thread cll of, 08 


liscea, characters of, 587 
Geeotnedinces! 518, 660 
- in, 617; markings on frustule 
20; sreolm of, 520; frustales of, 


wr, 588 
- Tgetromphalus for testing lenses, 888 
ee ‘tonal, with embryonal 


Goomerium, division of, 512; form of 
all, 515 
ax botrytis, sygospore of, 514 
Coemic dust, 1015 
Coates of Campylodiscus, 586 
‘Oostonella, silicious shell of, 700 
Cotyledons, 610 
Gover-glass, 880 
‘consequence of using, 19; as section 
lifter, 482 . 
— teeter, Zeise's, 881; Ross's, 881, 88 
ce varying thicknesses of, 880; ‘with 
ent: objectives, $80; cleaning 


on. g. Doon structure of frostule in 
sia, 519 note 
(Crab, '881; metamorphosis, 898; blood- 
corpuscles of, 962; ‘liver’ of, 971 

leg of, 898 

ly. See Tipula 
Oraterium pyriforme, 988 
‘Crayfish, 881; young of, 498 
‘Creation of structure by diaphragms, 68 
Oribrilsna figularis, 880 

gizzard of, 917; wings of, 993; 
+ sound-producing apparatus, 928. See 





of 
‘Grinctace, skeleton of, 816; larva of, 


sr on ‘aperture,’ 45; on redia- 
collection 


tion, 75; on of microscopes, 


Set oh 798, He 
‘Critical ang! ; image, a 3 
images, 


988; mode of obtaining, 852, | 


Crocus, pollen-grains of, 647 
Crouch’s adapter for parabolic speculum, 
381 


Crow silk,’ 499 

Crown glass, refractive index of, 5; 
‘composition of, 82 

‘Crusta petross of teeth, 949, 950 

‘Cavsracta, 881-895 

= larve of, collecting, 459 





cere 
Causracea, suctorial, 880 _ 





Cayrrocami, 462-609 

— preparation of, 497; stracture of, 462— 
485; reproduction of, 465-479 ; litera- 
ture, 608; passage to PHaNzRooamis, 
609 


Cryptoraphidee, 637 

Crystalline forms, list of, for microscope,.. 
1019 

Crystallisation, microscopic examination. 

ft, 1016, 1017 

— effect of temperature on, 1017 

— preservation of specimens of, 1020 

Crystallites, 995 

— in glass cavities, 997 








997; inclusions ins $01, 998 ; micro 
scopical structure of, 990; opti 
Portion ‘and chemical ‘conatitution,. 
1002; sa microscopic objects, 1016 ; 
of mom, 1016; a0 objects for’ polari- 
‘scope, 1017 

Ctenaria ctenophora, 801 note 

Ctenoid scales, 951 


pores 
Ctenostomata, characters. of, 888. 
Cucurbitacee, pollen-grains of, 646 
Cuff’s micrometer, 140; microscope, 1. 
Culicide, antenne of, ‘913; larve, ‘ioe 


2 
—imperiatia, scales ot, 899 ; elytra of, 905. 
Curculionidae, 905; foot of, 994; suckers. 
on foot of, 926 
Currant, parenchyme of fruit, 618 ; pollen-- 
tubes of, 648 
Curvature of the field, 392 
Curved scissors, for section cutting, 897 
‘Cushion-stur, 815.’ See Goniaster 
Cuticle, 965, 966 
= of leaves, 688; of Ciliata, 700 
ic Res 





Gutloraas Sonjugation of, 556 
Cuttle-fish, 858, 868. See Sepia 
= aire’ of, structure, 858; imi- 


028 
‘cuitie'Gah bone,’ structure of, 858 
Cyanaa capillata, ephyre of, 799; scy- 

Phistoma of, 799; strobila, 799 
Cyanthus minor, seed of, 649 
Cyatholiths, 672-674; artificially pro- 

‘duced, 1088 
Cycadee, 609 
Cycas, raphides of, 621 
Cyclammina cancellata, 741, 748 
Cyclical mode of growth in shell of° 

Foraminifera, 738 
Gyetoctypens, 764; shell of, 78 

compared with ‘onbutoliien 736, 760 
Cyeloid weals, 063 












sm, BOK 
nus candies, S68 
Ghehere cot. sae 
Cytherina, aivells of, i ebalk, 1009 
‘Cytodes, contrasted with plastid, 652 
CYytoplann, 407 


D 


Drywdale’s_ moint 


Dallinger and stacey 
2501" tripod ole history” of 








wicula, Ro, wa 

test objects, G30 on nucleus of 

monady, 68? 

Dallinger’s thermo-static stage, 

Dolitagerta. Drysdale 
strncture of, 688; nocleus of, 

Dalyell (J. G.} on Hydra tuba, 708 

Dames geniculatus, proventriculus of, 
006 

Dammar, as a preservative medium, 441; 
‘ws amounting medium, 444; refraative 
index of, 445 

Dandelion, laticiferous tissue of, 020 ; 
pollen-gruins of, G47 

Daphnia, eye of, 834; mouth of, 868, 
840; egge of, S84; ephippial eggs of, 


and 


cc 
Daphnia puter, 896 
Darwin (Charles) on Cirripedia, 891 


Datura, soods of, 649 
Davis on desiccation of Rotifera, 718 
note 





*Day-fly. 

*Dead-man’s toom, 803, 

Deane’s medium 'for mounting insects, 
407 


Soo Ephemera 
See Aleyonium 





Deh sep pres 0 of val 
Deruil shsloton of Vertebrata, 960 
Dermaleichi, 12, 088 


i 
$00; cellulose bos 
inne seal, £105 ptt 


610; endochrome, ae 

510; cycloxin in, 810; binary diviaiom: 

OL ‘S18; clans 

fiation, of 8 %: abitat fy B18, B18: 

— Hantasoh’s yon ‘mothod of pre 
serving, 444 


‘873 ; of Tomopteris, 878; of | 


INDEX 


~ Dienthus, wood of, 648 
yyilaus, parenchyme of, 618 

‘Dispengm 218, 255, 288, 821. 

— with two openings for double illumina- 

: tion, 106 

— ese of, 261 

= Zaise’s iris, 246, 248 ; calotte, 247; 
im ore-rinces, 895; for use in testing 


obigot Flasscs, 829 

iy’s microscope, 147 

Didtones 517; frustules of, 
girdle of, 518 

~ ire, chains of, 584 

Dia ToMaces, 477, 509, 516-554 

— Miller's type-slide, 986 ; perforated 
‘membrane of, examined with annular 
illumination, 862; mode of examina- 
tion of, 368; preserved by osinic acid, 
428; sllicions coat, refractive index of, 
445; mounting, 450; stiper of, 517, 
518; ce, Al, 522; 
sea kioee oe: of, 592; binary division of, 
528, 524; reproduction of, 528-527; 

« lassification of, 527, 582; ‘placochro- 
matic, 97; coccochromatic, 573 
movements of, 528; conjugation of, 

zygoxpores of, 598; gonids of, 
529; habits of, 548, 549; habitats of, 
549; distribution of, 549; fossil forms 
‘of, 850, 551; used ax food, 651 ; collect- 
ing, 55; cleaning, 659, 558 note; 
mounting, 558 ; as food of Ciliata, 708 ; 
in mad of Levant, 1007 

Diatom-trustules in ooze, 1008 

Diatomin, 517 

Diatoms ‘in stomach of ascidians, | 
Holothuria, &c., 544, 558 

Diatoms. Seo Distowacer, 

Dichroism, 1019 

Dickiea, 538 

Dicotyledonous stems, fossilised, 1005 

Drcorrievons, 625; stom of medullary 
rays of, 627; epiderm of, 637 

Dict yocalyz pumicous, 785 

Dictyochya fbu 

Dictyocysta, 

Diet "peruviana, winged seed, 49 


pyoloma 
clathrus, 771 
Dietyota, odapheres of, 886 
‘Didemnians, ais baa 
Dadymium terpula, plasmode 
Differential sorew, Campbell’sfine adjust- 
ment, 164, 188-198 
Differential staining, 430 
Differentiation of cell, 468 


Piftusia, 610; teat of, 071 


tion, 62 

—Abbe's theory of, and homogeneous 
immersion, 812 

— Fraunhofer’s law, 57 

7 Fays are image-forming, 59 
— spectra, 94, 67; phenomens, 63, 64; 
image, 64, 72; experiments, 66-70; fan 
of isolated corpuscles, 72; problem, 7 
pencil, 74, 75; hypothesis of Abbe, 7 





817, 518; 




















1067 


DRE 


fan, 75; theory, application of, 76, 78; 
bans, 288; phenomens, Abbe's experi- 
mente, 87¢ host, 877, 

Digestive vesicles of Ciliata, 708 

Digitatis, seeds of, 649 

Dimorphism in Foraminifera, 127 

Dinobryon, 690 

Dinoftageliata, 605 

Dinomastigophora, 695 note 

Dioptric investigations by Gauss, 108-112 

Dioptrical image, 80, 72 

Diorite, fluid inclusions in, 997 

Dipping tubes, 209 

Diptera, 897; eyes of, 911; antennm of, 
#12; mouth-parts of, 915; wings of, 
993; ovipositor of, 027; imaginal discs 
of, 981 

Direct division of nucleus, 468 

‘Directive vesicles’ of egg of Purpura, 
861 

Disc-holder, Beck's, 288 

Discida, 71 

Discoliths, 672-674; artificially produced, 
1033 

Discorbina, 749 

< globutaris, 728 

Disintegration of rock-masses, 999 

Dispersion, 9, 17; in glass, 81 

—and desiccation of encysted Ciliata, 
709 

jeraive power, 2, 9, 18; of fintglass,10 

Dissecting apparatus, 894 
— microscope, Beck's histological, 197, 
198; Stepl enson’s binocular, 201, 203, 
805; Huxley's, 204, 205; Zeisu's, 205, 

206; Beck's binocular, 207 

Distance of projection of image, 26, 27 

Distinet vision 

Diatome, life Natory of, 870 

= hepaticum, 869 

Divergence of light, 18 

ini'x compound miei , 181 

Division, binary, of cells, 468; of deamids 
511 

— artificial, of Actinospherium, 666 note 

— of naiads, 880 

Dobie's line, 978 

Dog-finh, scales of, 252 

D'Orbigny on plan of growth of Fura- 
minifera, T24 

Doris, spicules in mantle, 852, 858 ; nida- 
mentum of, 858; eggs of, B68; 
of, imitated, 1029 

— bilameltata, development of, 859-861 

— pilosa, palate of, 855 

—‘tuberculata, palate of, 855 

Double illumination, Stephenson's me- 
thod, 106 

Doublet, Wollaston’, 96, 151 
ragmuta, of sponger, 764 

Dragon-iew wing of, 039 | 

n-fly, facets in eyes of, 907 

— Bee Libeltula 

Draparnaldia glomerata, 508 

Draw-tube of mi ‘155 

Drebbel’s modification of Keplerian 
telescope, 123 






































preparing, #84; mounting, 24 
a= aealasonelil mined OF ee 1007 
Ecurxopensata, larva of, collecting, 


459 
— 808-827; skeleton of, 808, 815, 510, 
814; spines of, Goes #15; pedi- 
celaain oft LB ait oy BAY BB 
tion of skeleton, spines, &e., 
i internal keloton, £18; larvae of, 


Echinoderms, decalcification of, 426 

Echinoisdea, skeleton of, 505; spines of, 
801, 818; pedicellaria of, 81 larva 
of, '822; direct development in, 824 
note 

Echinometra, spine of, 810, 810; colour 

Koh mus, shell ot, 800, 810 spines of, 
ichinus, of, 809, 810; spines 
800; teeth of, S13 





— lividus, coloured spines of, 811 

Ectocarpaces, 555 

Eotocarpus siliculorus, conjugation of, 
5568 


Eetoderm, 601 
Eotoplaamn, 463 
Betoprocta, 888 
Eetosare, 


404; in Rihisopoda, 658; 

ntaon U68; of Ciliata, 099 

Edentata, cement in teeth of, 960 

netamorphowis of, 804 

mersion paraboloid, 269 

Edwards (A. ML.) on supposed * swarm 

of Amarbar, 609 

Kel, scales of, 081 

“Egg without shell,’ coneretionary aphe- 

ws in, 1021 . 
‘gxroupsule of Cyclopr, 885 

Eegg-nace of Lernera, 800 

Egzg-shell membrane, 062 

Exge of Sepiola, Doris, 866; of Acarina, 
9S, O20; of inmvets, U2S 




















Ei 

Entomophthore, 971 

Entomostracd, 881, 68, 865; dowicos- 
Pp, ‘S88; development 
S00; ere ch 206 ; "non-sexual repros 

— collecting, 450 

— Rotifers spon, 718 . 

Rntomoatenees eee Oe of Ciliata, 


INDEX 





: 764; 


‘normal cast of, 765; 
layer, 768; peoudopodia 
+ @f, 706; young of, 767 


of “olifora, 11 
jana, 799; of Chrysaora, 


Epiblast, 651 note 
‘Bpiderm of leaves, 687 


1001 
ilobium, emission of pollen-tubes, 
OT 
gz aah 815 
en-tubes of, 648 


Beep ‘af Mucoriné, 810 
Epistome of Polysoa, 888; of Actino- 
trocha, 


874 
Ere collecting, 457 
thelia preservative for, 448 
= 967, 968 
emia, conjugation of 629; xyR- 


= Porouia’ 533 
“Equiconcave lens, 22 
“Bguisetacea, 605; in coal, 1006 


Equitant leaves of Iris, &c., 648 

binocular, Stephenson's 108 
5pm ‘Stephenson's, 
Jerkoe, scods of, 649 
Bristalis, eye of, 911; antenns of, 919 
Error of eto, 382 
‘mechanival stage, 166 
1, eye-apot of, 703 
polyzoaries of, 888; 

perivisoeral cavity, 651 
Ether as a solvent, 441 
‘Ether-spray microtome, 418; Rutherford 
00, 419 
hava si ‘phonophora, ‘714, 776 
resis oulgaris, BO 
Y 








1069 
FAR 


Euler's microscope, 146 

Euler on achromatic microscopes, 145 
Eunotia, 588 

Eunotiee, characters of 558 

Euphorbiacee, laticiferous tissue of, 


Euphrasia, mioropyle of, 648 

Euplectella lum, 785 note 

Eupodiscea, of, BAL 

Eurotium repens, 872 

Evening primrose, emission of pollen- 
tubes, 647 

‘ Exclamation markings oe 

Excrotory organ of eros Te; ot 

tide, 985 


Baar (8) on" the of 
mer (5) om image in eye 





mpyris, 

Exogenous stems, 625, 

— stem, structure of, 688 

—and " endogenous’ stems contrasted, 


Bxogenn fb 
‘xogens, fibro-vascular bundles, 622, 628 ; 
juliary sheath of, 628; spiral vee- 
sels in, 628 
Exoskeleton of decapod: 


808 

Exospores of mosses, 507; of ferns, 602 ; 
of Blymenomyeetes, S76 

Extine of pollen-grains, 644; markings 


on, 645 
Eye, accommodation of, 68 
- vot Pecten, 865; of Onchidium, 865 ; 
of of slog, 865; of anail, 865; of arthro- 
stracture of, 907 
syed af compound microscope, 86, 








Eye-lens, 821 
Bye piece, Abbe's compensation, 42, 022; 
Hoyghenian, 42 cline 42, 899; 
's, 43, 


eden ro 4a, BiB; Airy, 681; Cam: 

re 21; Huy ", 8S 

inoealar, Tollos’ 102; Abbe's, 108 

- Kellner, as condenser, 177 

= r, 298; multi of, 
240; Pie icesob, pre focting, 898; 
micrometer, 818; eld Sr d3; pointer 

in, 825; diaphragms in, 825; index, 825 

— stereoscopic, Abbe’s, 108 

Eye-piooes, classification of, by Abbe, 84; 

‘compensating, sitive, Bal; 

moguaive, 8310990; solid, 829, eld of, 
898; working, 888; penal ‘328. 

Eyes on Chiton shells, 865 

— compound, of insects, 908, 907 

— compound, 906-911; simple 906, 910; 
preparing, 910; mounting, 91 








F 
Faber, inventor of the name microsoope, 
(26, 127 


Faletform young of Coccidia, 677 
Falee images, 862 
medium, 448, 449; for mount- 








insects, 
ran (A.) on structure of Polysoa, 883 
note 





1070 
wan 
Werraec Dire ts 
948, 964, 966, D005, cupllory 


ereerk 
Fenthems uat-tsd for, ta 


Feathor-star,’ 884. Seo Antedow 
Fete, me yk dino #0 


wees heres, 900; in tbe conta ‘of euros, 
622; of Exogens, 22, 628; of Phanero- 


625 
eee — of Vertebrates, 148 
902; white, 065, 964; yellow, 


Piatto i; applied to eyelens by 


iy pe hanes Soy hey! mos peered 
500; fruetifiention af, @00; prothall 
ee eee 3 





‘Filiferous capeules.' See Threadeells 
ain Dy rtp Maltwood's, 246; Panto- 






161; o's, 1825 Oba 

jauser's wpiral, 161; applied to the 

by Powell, 150 ; by moving the wh 

body, 188; by simply moving the nose: 

vince, 18H, 161 :for Powell and Lealand's 

sub-stage, 174; of Rows model, 177: 

Wale’ 183; x Beck's students’ 

jcroseopa, 190 

fly, antenna of, 021 

‘ Fire-dly,' 870. See Lempyris 

Fieh, ciroulation in tail of, USI ; 
wae, OSL 

* Fiah-louse,’ 890 

concretions in, 1021 

cium in bone of, 040; 

cement of teeth in,950 : pla 

of, 950; red bloed-corpuse 

60; pigrmenticelle of, 90 

muscle fibre of; 973; gills of, 23, 9» 

Fission in Lich berkuchnia,| 608; of Mowes, 

















a yolks 



















Pens one 


mean, 275 


ot, 
enter chromatic, 1 
Postal atipgaic, 8 









24; examination 
slides for mounting, 900; method tor 











INDEX 


yor’ 


““wectionising, 491 note; decalcification | 





of, 426; structure of, 720; chamberleta 
in, 7238, 728, 729, 780 ; cyctioal mode of 
growth in, 7 in, 138; shells, 
734; vitreous shells, 724; tabulation of 
sbell in, 724, 725; pl of growth, 
‘734, 729; rotaline type, 725; numma- 


nea, 726 ; inter 


‘mediato akeleton of, 790; canal systera | 


of, 726 ; fossilised forms of, 726, 729, 
‘781, 749, 762; dimorphism in, 727; se- 
condary septa in, 798; Arenacea, 785 





isomorphs, 789; nodosarine type, | 


sandy i 

740; Vitrea. 744; internal caste, 748, 
762 note; nummuline series, 751; alar 
788, TBs Jatersaptal 

canals, 765; margin in, 755, 759; 
collecting, 760; method of separating | 
from sand, ke, 769; mounting, ting, 770; 1 
baie ‘compared with those of den- | 

fine, 944; in mud of Levant, 1007; in 
rocks, 1007; internal casts of, 1019. ° 
Forbes, on reproduction of Sertulariida, 


301 


_> ce 387 
Porficula, antennm of, 12 


Forfteulida, wings of, 
Fon: of Sbjects and fo focal alteration, | 


Formation of microscopic imagen, 48 

«Formed material,’ 942; of fibrous tissue, 
948; of dentine, 044 

Fossil’ coniferous wood, 630, 1005 

— crinoids, 816; echinids, 816 


Sito 
Lituole, 741 
— Radiolaria, 771, 778 note 
= Saccammina, 787 
— wood, 681 
Fossilised Foraminifera (Bosotn), 702 | 
sections of, 687 





726, 749-750 


t 





igilaric 
mntation of nucleus, 468 
Fragnhoter's law of diffraction, 67 
— achromatic doublet, 146 
ines, 278, 974 
Fredericella, collecting, 458 
Free-cell formation, 485, 644 








in embryo-sac, 464, 406 

Freezing apperstas for ‘Thoma’s (Jung's) 
microtome, 405, 406 

— microtome, Hayes's, 411; Cathcart's, 
412, 418 

= imbedding by, 

Freanel on Selligue and Adams's micro- 
scope, 146; on range of magnification, 
M7 

Freyana heteropus, legs of, 984 

Fripp 's method of testing object-ylasues, , 





Frog, blood - corpuscles of, 956, 969; | 
muscle fibre of, 973; papille on tongue 
of, 977; circulation in mesentery of, 





1076 


oar: 


005 circulation in tongue ol, 960; lang 
987 
Frog's bladder, histology of, as seen with 
‘apochromatic, 818 
— Rot, apitheliam of web of, 969; cir- 
culation in web of, 979 
Frond of Pheosporee, 885 
Fructifieation, gonidial, 470; 
470 


— of thallophytes, 470; of Ascomycet 
571; of lichens, 578; of mosses, 59! 
of forns, 600; of Equisetacec, 605 

Fruit juice as w preservative medium, 
442 

Frustules of Diatomacea, 517, 518;: 
structure of, 518, 519 note; girdle, 518; 

8 of, 518, 519; osticlea in, 619; 

‘ings on, 520; character of, as basis. 
of classification, 682; of Coscinodiscus,. 
538 

Fucacea, 556; conceptacles of, 556 

Fuchsia, pollen-grains of, 647 

Fucus, 555 

Fucus jearpus, 556-558 

Penicens 

Fnlgoride, wings of, 923 

Funaria Ayrrometrie, 504 

— sporange of, 596 

Fuxat, 470, 562-589 

— preparation of, 497; zymotic action of, 
462; alternation of erations in 
classification of, 668; parasitic on 
insects, 571 

Fungia, lamelle of, 608 

Fangiform pepillee, 977 

Fungin, 562 

Fungus-céllulose, 562 

Fusion in Dallingeria, 684 

Fuss's description of a microscope, 145 

Fusulina, 750,751, 1012 

Fusulina-limestone, 750, 1007 * 


sexual, 














G 

Gabbro, 1016 

— fluid inclusions in, 997 

Gad-fly, oviporitor of, 997 

— See Tabanus 

Gaillonella procera, 551 

= granulata, 551 

iseriata, B61 

Galileo, inventor of the compound micro= 
scope, 122-127 ; Viviani’s life of, 1 
his invention of eompound microncope, 
Wodderborn on, 128; his occhialino 
123, 196; hin occhiale, 124, 125; his 
microscope, 120 

all-flies,’ ovipositor of, 927 

Galley-worms. See Myriopoda 

Gamuaside, legn of, 984; integument of, 
‘9384; Malpighian vessel of, 935; heart 
of, 085; trachem of, 985 ; characters of, 
986 ; reproductive organs of, 936 

Gamaaua terribilia, mandibles of, 983 

nglion-globules (cells), 975 
lionie celle, 978 




















2072 
Gax 


Ganoid reales, 952 

Garlic, raphides of, 621 

Garneta, 1000 

1s bubbles in glass cavities, 997 

Gaseous inclusions in crystals, 998 

Gaxtrea, Haeckel on, 677 

Gastropoda, palates of, mounting, 450; 
palate of, 848; development of, 843; 
hhell structure ; embryonic 

velopinent of, 858-864; organs of 
hearing in, 865 
diastrala, 651; -stage in Colenterata, 


























G51; formation of, 651 note; of 20% 
phytes, 786; of Gastropoda, 859; of 
blowfly, 981 

Gastrulm of sponges, 781 





€auss's optical investigations, 108-112 ; 
his dioptric investigations, 108-119; 
his system, practical example of, 112- 
118 

Gelatinous nerye-fibres, 976 

— — in sympathetic, 978 

Gemellaria, polyzoary of, 

Gemmme of Marchantia, 691, 592; of 
Salpingaca, 689; of Suctoria, 698; in 
Foraminifera, 728; of Polyzoa, 880 

Gemmation and ‘shape of shell in Fora- 
minifera, 721 

Gemmules of Noctiluea, 094 ; of sponges, 
781 

Gentiana, seeds of, 649 

Geodia, spicules of, 784, 1008 

Gephyrean worm, 8 

Geranium, glandular hairs of, 689 ; cells 
of pollen-chambers, 645 ; pollen-grains, 

646 



























ells of Ti 484; of ferns, 
4; of Marchantia, 598; of mosses, 
6; of Phanerogams, 609 ; of sponges, 
1; of Hydra, 790 
‘Germinal matter,’ 942; of fibrous tissue, 
‘M8; of dentine, 944 
Geaneria, seeds of, 649 


INDEX 


Opa 

Glodigerina bulloides, 745 ;in 
1007 

—conglobata, 746 

— ooze, 748, 1007; resemblam 
1009 


— rubra, colour of, 724 

Globigerine shell, sandy isome 

Glolngerinida, 745 

Globule of Chara, 507, 508 

Glochidia of Aviordon, B57 

Glaocapsa, 477; as ganid of | 

Glow-worm, 879; antennm of, 

Glue and boney cement, 354 

Glaten of grass sends, 650 

Glycerin, as preservative me 
Hantzsch’s method, 444 ; aa 
tive medium, Beale's met 

— -jelly, Lawrence’s mountil 
449; solvent for CaCOy, 444; 
ing insects, 497 ; for mountin 
971 

Gyciphague Krameri, 987 

— palmnifer, 982 

— platygaster, 987 

— plumiger, 932; hairs of, 98 

Gnathostomata (Crastacesn), 

Goadby’s solution for mountin, 
971 

Goes (Dr.) on affinity of Carpe 

Goette on development of Ant 

Gold size, 388 

Gomphonema, stipe of, 518, 5 
mentsof, 681; attacked by Fa 
055 

—geminatum, 545, 546; stipe 
gracile, 551 
omphonemee, characters of, 

Goniaster equestris, spines of, 

Gonidial cells, 470 

— fruetification, 470 

— layer of lichens, 87 

Gonidiophores af Peronosporn 

Gonids, or non-sexual spores « 























INDEX 


GRA 


tatophora parallela, 560 
mtina, 536 

ilissima, 587 

1016 

‘inclusions in, 997 

4, 741, 785; spicule of, 1008 
nodes of, 626; silex in epiderm 
9; palew of, 640; seed of, 649 
apper, gizzard of, 917; wings of, 





ands, microscopic constituents of, 


ina, characters of, 674; movement 
5 

ntea, in lobster, 674 note 

uridis, O76 

inida, 674 

+ (J. W.) on Eosodn, 768 note 

+ (W.) on species of diatoms, 580 | 


+ on Spatangidium, 689; on | 
ratium, 648 note 
atter, 976 | 
's turn-table, 891 
sia, 559 
sections of hard substances, 420 
‘microscope, 184 1 
, 659, 660, 721 

Arcella, peendopodis, of, con- 





4, 671 

-mass of rocks, 995 

sel, pollen-grains of, 647 

3 slides, Botterill’s, 280; Mad- 


289, 290; Lewis's, 289 | 
vells, 640 H 
eed,’ 559 

ad glycerin, 448; and syrup, 
rvative medium, 448 

ding for vegetable substances, 


¢, formula, 885; for freezing, 418 
8, latex of, 620 

xX, as a mounting medium, 444; 
of refraction, 445 

475 

shroa, 792 

lamata, 888 

sperms, fossilised, 1005 
rative apparatus in, compared 
Sryptogame, 609 














1073 


HEM 


+ tgusous solution, 482; Weigerts, 488; 
fill’s method, 488 
Hemionitis, sori of, 600 
Haime (Jules) on development of Tri 
choda, 707 
« Hair-moss,’ 596 
‘ Hair-worm,’ 868 
Hairs of leaves, 689; of insects, 904; of 
Acarina, 984; of mammals, 958 
Halicarida, 987 3 
Haliomma Humboldtis, 116 
— hystriz, 772 
Haliotis (diatom), 542 
— (mollusc), shell structure of, 852; 
palate of, 855 
Haliphysema, 789; sponge-spicules in, 
TAT 
Haller on anditory organs of Acarina, 
A 
Hialteres of Diptera, 924 
Hand-magnifier, Brewster's, 87 
Hanagirg on movement of Oscillariacea, 
490 
Hantzsch's glycerin method for desmids, 
444 
Haplophragmium, 789 
= globigeriniforme, 788 
Hardening agents, 427, 428 
absolute alcohol, 498; chromic acid, 
428; osmic acid, 428 ; picric acid, 428 
Hardy's fat bottle for collecting, 457 
Harpalus, antenne of, 912. 
Harting on Janssen’s microscope, 122 ; 
experiments on formation of con- 











cretions, 1023 
Hartnack on immersion system, 27 
Hartnack's model, 210; his stage, 211 





Harteoeker’s simple microscope, 185 ; hin 
condenser, 248 

‘Hart's-tongue,’ 600. See Scolopen- 
drium 

‘ Harvest-bug;’ 987 

‘Haus’ of Appendicularia. 842 

Hoaustellate mouth, 916 

Haustellium, 916 


| Haversian canals in bone, 946, 947 





yeraft (J. B.) on structure of striated 
muscle fibre, 973 

‘a ether freezing microtome, 411; 
minimum thickness of sections there- 
with, 412 





Hazel, peculiar stem of, 628; pollen- 


H 


on budding in Polysoa, 881 note 
1 (E.) on Monera, 677 note 

© Gastraa theory, 677 note 
Radiolaria, 7725’ on nature of 
en, 749; on Hydrorotin affinity of 
phora, 801 note 

Hertwig on classification of 
aarians, 778 note 

ococeus, red phase of Proto- 
4,473 

wineus, 486 

oxylin, alcoholic solution, 488; , 


grains of, 647 
Hearing, o 


ns of, in Gastropoda, 865 ; 
in Cephal iid 


fa, 865 


! Heart of ascidians, 886; of Acarina, 935 


Heartsease, pollen-tubes of, 648 

‘ Heart-wood,’ 629 

Heating-bath, Mayer's, 898 

Heliopelta, 518, 540 

Heliozoa, characters of, 659; examples 
of, 662-667 ; pseudopodia of, 770 

Heliz pomatia, teeth of, 854 

= hortensis, palate of, 854 

Heller's porcelain cement, 445 

Helmholtz on aperture, 47 

Hematite in carnallite, 998 








32 





a ee development 


= - TL: wings uf, 28 














* INDE: 








HYD 
Honklets on wings of Himenop 
Heplophora, 93 
— maxille af, 934 
Hormogunes of Oscillariaces, 
Rivulariacea, 190; of Seyte 
490; of Nostoc, 491 
Hormceina globulifera, 18, 7 
— Carpenteri, 740 
Hornbiende, 1001 
— correded crystals of, 995; pl 
im, 1008 
Hornet, w 
Borns, 953. 
Horny substances, chemical 














cof, 923; sting of, 








£ corn-graips, 644 
m the ectosare of Am 
scoliths, 672 


eye-picce and 


nm of, 821 


i Foraminifera 








INDEX 


HYD 
and marine mites, 987 
nerves of, 978 
‘of Ascomycetes, 671 ; of Basidio- 
876; of Hymenomycetes, 576 
nylon jeotes, 816; pileus of, 576; 
stipe of, 576 
897 ; eyes of, 911; mouth- 
Parts of, 915; wings of, 922; ating of, 
926, 937; oripositor of, 996, 98 937 Ee 
n 


chambers at, G48 815; seeds of, 40 


; Boegioun, seed of, 649 

+ Hyper of ydrodictyom, 495, 
ag 

aes Ory of Tyroglyphide, 987 





meaning of, 470 note 


I 


of, 689 


‘Ioe-plant 
oripeaitor of, 997 


Tenbmonste 


867 
— power naan 54; compared 
with penetrating power, 886 
‘hemination ete ion, B44 
— for opaque objects, 14 
— oblique, 170, 171, 8815 in Zentmayer’s 


ronan by rotexion, 
jue, 28) from the nm 
355; By dittased daylight, 808; for 
Bark groond. 886; experiments in, 
857; tic, means of obtain- 
ing, 860, 861; annular, 862; double, 
cbjests ‘for study vith, 368; with 
small cones, an cease of errors in 





interpretation, 

Lluminator, Stephenson's catadioptric, 
170, 968-265; oblique, 170; white 
cload, 172; 'Wenham’s reflex, 266, 

, 267-260; Swift's oub- 






985; Toles’ vertical, 285 
‘Image, real, 14 note; virtual, 14 note, 821 ; 
conjagnta, 945 in conjugate, 24; 


gborption’ or “aioptrical, 64 ; diffrac: 
mm, 64; negative, 64; posi q 

95; real object, 891; definition 
of, 880; formed by compound eye, 908, 


Tuanges, by diffraction, djoptrio and 
interference, 72 
Imaginal discs in larva of blowfly, 081 
processes, 414; simple, 414; 
eel a paraffin, 415; metal 
case for, 415 
— masoos, 416; paraffin, 417; wax, 417; 
celia, 417 
— by coagulation or freezing, 418 
Immersion lenses and vertical illumina- 
285, 286 
ous, outcome of Abbe’s 
theory of Siac 812, 818 
—— water, Zeiss 


1075 


INT 


| Immersion lenses, water, Amici’s, 810; 
Powell and UTesland’s 810, 818; Praz- 
mowakl and Hartnack’s, 810; ‘Toles’, 


Sechivi 28; examination of, 881 
tem, 27-29 ; invented by Amici, 27 
Imperfect achromatism, cause of yellow- 
ness, 860 
jimprenionable on organs’ in Ciliato, 708 


Tncident vey, 

Incus of Rolifera, 15 
Index eye-piece, 8: 

— of visit 














487 
raion of nucleus, 468, 
Indusium in ferns, 600 
Inflection of diverging rays, 62 


‘Infusoria, oamic acid, 
{ays ood of Actin rye, 668; 
Ehrenberg’s wrotk on, 6785. ciliate 
679; f, 679 unicellular 





nature of, 680 note 

Infusorial earth, 586, 588, 540, 542, 546, 
‘550, 59, 771; from’ Barbadoes, 771, 774 

Injected preparations, 984 

Inoceramus, portions of shell of, in chalk, 
1009 


Inazcrs, 896-981 
‘of, wooden slides for mounting, 


— parasitic fangi in, 578-574 
— mounting media for, 897; integument 
of, 898; tegumer ndages of, 
896; scales of, 699-004 ; hairs of, 904; 
parte of head, 906; eyes, 906-911; 
antenne of, 911; mouth-parts of, 918; 
circulation of blood, us i ctlimentary 
canal, 917; wings of, 8, 939-094; 
trachew of, 918 ; stipmale of 919; 
sound-producing ‘apparatus, 998; o1 
, 994 ; organ of 








tren aekclopment a “oa; ¢ 
of, 971 

Insect work, polarised light for, 866 
Integument of insects, 898; of Acarina, 


984 
Integuments of ovale, 610 
Intensity of light, mesesaries for, 350 
fular substance, 94 





cartilage, 


ec 
Intercostal points, Stephenson on, 78 ; 
not revelation of real stracture, 78 
Interference, 62 
image, 72 






Keleton in Foraminifera, 
ida, 745; of Calea- 
7 


uit 
Internal caste of Rotalia, 748; of Textu- 
laria, 748; of Hosoin, 785; of wood, 





1005; of masand, 1012 


822 


in greet 





INDEX 1077 


LaT 


videa, 822; of Crinoidea, 824; 
of fly, 981; of 





Phanerogams, 620 
‘squamaria, embryo of, 648 
us tubes, free-cell formation 


of Phanerogams, 620 
in rocks, 762, 767 

sr green seaweed, 487 
‘glycerin jelly, 448 

piderm of, 687; internal struc- 


; 641; mode of preparation for | 


ation of, 642 

t) 

1oek’s simple microscope, 184 
thod of selecting Foraminifera, 


sects, 924, 926 ; of Acarina, 982, 


ose, seeds of, 610 a 
1 palmacinctum, 982; hairs of, 


vjectives, 820 
pochromatic objective, 820 
rerical, 12; biconvex, 12, 18; 
concave, 18; diverging meniscus, 
sno-convex, 18, 15, 38, 87; con- 
;meniscus, 18; biconcave, 18; 
convex, focal ‘length of, 15; 
biconeave, 16; crossed bicon- 
j equiconvex, 16, 22; Stanhope, 
dington, 87; Briicke, 88 
‘argon’s palace, 121 
ion of, 121-122 
aatic, ‘Charles's, 146; Barlow's, 


afraction by, 10, 25 

geneous immersion, of Powell 
aland, 29; of Zeiss, 29 

2; for apochromatic objectives, 


ration of 87 | " 
ng power of, 64; amplifying 
stab, 26 
t by Coscinodiscus, 888 
2, 801 
1, seeds of, 649 
tus curvicollia, scales of, 908 
dra, 607, 1008 
era, scales of, 899, 900; wings of, 
18; scales of, mounting, 906; 
, 911; antennm of, 912; mouth- 
116; eggs of, 929 
us, bony scale of, 946, 952 
robi, 607 

saccharina, scales of, 900, 901 
la, 908 
; 888; extension of perivisceral 
3f, 851; mode of growth in, 628 
2us (ally of Noctiluca), 604 note 
sium scotinum, 578 
iz, form of, 581 
utumnalis, 987 
889 note, 890 

556 
laticiferous tissue, 620 














Liv 


Leucite, mineral inclusions in, 998; 
| _ anomalies in, 1008 
Lever of contact, Ross's, for testing 
covers, 881 
| Libellula, 911; respiratory apparatus of 
larva, 921 
Liber, or inner bark, 688 
faces: 576-579 ; fangus-constituents 
579 
Licmophora, stipe of, 618-588, 584; 
| _ Sabella of, 584 
| — flabellata, 517, 588 
Licmophorec, 545 
— characters of, 588; vitte of, 584 
Lieberkuehnia, movement of, 657 
— paludosa, 658 
Teragners 850-089 ‘i 
jieberkiihn’s microscope, 188 ; his specu- 
Tum, 282-284 
‘Ligamentum nuche,' structure of, 964 
Light; refraction of, 2; recomposition 
of, by prisms, 18; convergence of, 18; 
path of, through com microscope, 
40; quantity of, 50, 51, 54; emission 
of, 51, 54; quantity of, and sperture, 
54 note; cone of, 170; monochromatic, 
71, 872; intensity of, necessaries for, 
859 


— modifiers, 284 
Lignified tissue, test for, 440 


Lignites, 1005 
um vite, wood of, 629 
zie pith of, 611 


Lilium, expotimente with pollen-graina 

‘Lily-stara,’ 894, See Crinoidea 

Limaz mazimus, palate of, 854 

— shell of, imitated, 1038 

= rufus, shell stracture of, 852, 858 

Lime, raphides of, 621 

Limestone rocks, 1007 

Limnaus stagnalis, nidamentum of, 
868; velum of, 860 

Limnocarida, characters of, 987 

Limnocharia, seeds of, 649 

Limnocodium, intracellular digestion 
in, 787 

Limpet. See Patella 

Limulus, 881 

Linaria, seeds of, 649 

Lister's strate for support of body, 147; 
his influence on improvement of Eng- 
lish achromatic object gasses, 148; 
his zooph; gh, 297 ; his di 
of two aplanatic foci, 804; his note on 
Chevalier’s objectives, 804; his infu- 
ence on microscopical optics, 805; his 
triple-front combination, 809 

| Léstrophorus, 988 

| Eithastertseus radiatus, 650 
ithistid sponges, spicules of, 784 

Lithoeyelta ocellua 71 

Lituola, 789 

| Lituole, large fossil forms of, 741 

| Dituolida, 789 
Live-boxes, 294, 295 

Liver, 971 


























1078 INDEX 
’ uy MEA 
72 Magnification, range of, 147 
vera to. Sos Hepatic power, 507; determination 
characters of, 089; examples of, 
oe Mahogany, size of ducts of, 24; stem of, 
‘Lobster, 81; metamorphosis of, 898 630 
‘Dobarorn,’ 872 Malacostraca, 
Loonll of snthars, O44 *Male’ ‘of 08 
Logan, iam of, 0175 oviponitors of, | Mallei of Rotifera, a 
Locusta, eyo of, 912 Malvighbo seat ot Goma, 985 
ia, 743 — Inger of skin in mammals, 
jont-calle of, 866 — bodies in vertobeute kidney, 971 
Lomas wy on spicalos in | Maltwood's finder, 240 
Alcyoniiiuny, €8 note Malea ‘Pollen-grains of, 646 
‘ Pride, of, 018 Make pollen-graing of, 648. 
icornes, om nas ‘eiartel roger et 
lyeod, $20, 8745 plates #, epldorinic 
Rete Mr 
5 , 3 % 
Loghorpermuin er winged seod | Stew at, 090; igs hy BO 
t Mammary glands, 
ia, 833 ‘Man, arrangement of enamel la tooth 
Lorica of Acineta, 007; of Ciliata, 100; 91; Jn tooth of, 000) Made 
‘of Rotifera, 715 955; muscle bre 5 lung of, 
Loup: 208 Mandibulate mouth, 918 
Tota ReiSenie 35; icahaity, 8%, | 6G oe eee 
y A wwil’s, 
322," 457: St i's oplanatio, 205; | Marble derived from Mmestomes, 1011 
Zoins's, 201 Marchantia, } archeganes 
ve, mounting media for, 897 506; prothallium of, O02; stomates 
Lovin on classi alne of palates | 640; elatans of, O45 
in Gast ee 856 98 = 
Lozosoma, jophore ol = 590-598 
Lubbock on Thysanura, 001; on Podwra | Afai ‘843; nacreous bayer of, 
903 , priamat of, 847 
Lucantes, 9121; antennm of, 912 3 cont” of 75 
Luminosity of Noctiluca, 690; of Cteno- | — ot Numemuliter, 750 
phora, 806; of annwlide, 879 Marine forms, 458 
Langs, circulation in, 980, 984 — glue for forming ‘cells,’ 383 
Lychnis, woods of, — mites, 987 
Lychnocanium faloiferum, 77% — work, tow-net for, 4585 dredge for, 468; 
= lwcerna, 771 | atick-net for, 459. 
Lycoperdon, 675; hymene of, 576 Marshall's compound microscope, 185, 
Lycopodiacee, 008; sn coal, 1008 areas aa 
jcopodien, farsipetia etomgal 
Tyninas, collecting, 457 Morahe pocket nedcting, 
Lymph corpuscles, 901 1085 is lance microscope, 3805 
Tysigenooe spaces in Ebanerogeras,618 | achromatia’ mlareesops, 145) hie me 
flecting Fj bls aches 
matic objective, 145, 
M ‘Marzoli’s achromatic lenses 208 
Masonelia, 736 
Maceration of vegetable timmes, 624; | Mastax of Rotifers, 715 
Sohulte's meted, 625 Masti Biateatan Ce 
Machitis polypoda, scole of, 902 Mastog! stipe ol BIR, A ti 
‘Machines for cutting hard sections, 424, | aheath of, 618, 648s evelorunen 
435 526; range of variation in, 
Macrocystie, 656 — lanceolata, 648 
Macronporos of Polytoma, 086; ot | — Sweithis, 643. 
sponges, 781 Matthews's method of #eetioniaing bard 
Macroutrotis Deospoila, young of 898,604 ene a 
ladder, cells of len rs, O46 [ny on 
‘Madre’ Acanthometra occurring i, 177 dp pha =~ 
Madreporus, 602 121; om Divini's 
Magenta as a selective stain, 486 Mayall's age, 104 
Magma, 996 Mayer's heating bath, 398 
Magnetite, 905 “‘Moadow-brown,’ eggs of 920 


2 





INDEX 


MEA 


vork,’ due to 0; 868 
al finger’ for sel diatoms, 


ents of the stage in Tully's 
pe, 147 
15 
all's, 165; Tolles’, 166; Zeiss's, 
sall's removable, 104° 

fh of microscope, 
ental, 108 
rays, 629 

tyledons, 627 
sheath’ of Exogens, 698; of 
Jons, 627 
fresh water, 787 
nounting, 888; of Hydroids, 
tked-eyed, 7923 development 
alternation of generations in, 
res of, 976 
4, collecting, 459 
894 
sree, 788 
e of certain Foraminifera, 








@ of Rhizocarpea, 606; of 
erous trees, 607; of Isoetea, 
Selaginellea, 607 
“um, teeth of, 950 


a of Ehrenberg, a hase in 


nent of Suctoria, 698; ik 


ores of Ulothriz, 486; of Ulva, 
Scenedusmes, 496 
lima, shell of, 851 
wea, 554 
a, 848, 846 
“itifera, 847 

collecting, 457; in confine- 
8 
le, 117 
a, eye of, 911; antenne of, 912; 
of larva, 920 
4, eye of, 907 
frustules of, 517, 580; auxo- 
sf, 625, 526, 680; sporules of, 
sospore of, 680 

587 

‘lis, 628, 524 
1, 528, 584; endochrome of, 527 
» characters of, 587; resem- 
0 Confervacee, 587 
\ putaminis, 962 
ipora, 882, 888 
iporida, 882 
itrate as a test for albuminous 
2e8, 440 
rwaki on movementsof diatoms, 









‘B45 

ers of, 533 

circulare, 517, 582, 588 

edia, 477 

“afingers,’ 808. See Alcyonium 
‘anthemum, seeds of, 649 
linum, epiderm of, 689 
us, conjugation of, 478; xygo- 
AT 





1079 
MIC 


Mesoderm of sponges, 780, 
Mosoglesa of Hydra, &c., 788 note 


Mesophlosum, 638. 

Metal case for imbodding, 418 b 

Met iam of rock-masses, 999, 1000; 
of limestones, 1011 

Metamorphosis of Lernaa, 890 ; 
Girripedia, 808; of Malacontraca, 

Metazoe, 652, 779 

Meteorites in oceanic sedimente, 1015 

Metschnikoff on acinetan character of 
Erythropsis, 702; on intracellular di- 
gestion, 787; on phagocytes, 961 note 

Mica, 1000, 1001 

Michael's (A.) opalescent mirror, 173 

Micrasterias denticulata, binary divi- 
sion of, 512; form of cell of, 675 

‘Mjcro-chemistry in Petrology, 1004; of 
poisons, 1028 

Micrococch, form of, 681 
icrocysts of Myzomycates, 585 

Microgroméa wocialis, 660, 061 

Microlites, 996 ; in glass-cavities, 997 

Micrometer, Cuf’s, 140 

— use of, 281 

— eye-piece, 828 

——Nelson’s new, 227, 228, 299; Jack- 
son’s, 282 

Miorometers, 226-988 

Micron, a, 89 note, 400 

Micro-petrology, 991 

“Microplate” of Bacterium rubescens, 

Micropyle in oval 
icropyle in ovule, 610; of Euphrasia, 
648; in orchids, &e, 613 

Microtcleren, 788,764 
‘croseope, Mayall on the, 119; history 
‘and evolution of the, 119-298; inven- 
tion of, 129 ; inventor of the name, 1! 
essentials in, 154-172; adjustments, 
156-165 ; stage of, 165-168; desiderata 
in, 915; [preservation of, 278 

—_Galileo’s, 129 ; Campani's, 180 
Pritehard's, with Continental fine a 
justment, 150; Ross-Jackson model, 
161; Powell's (H.), 158; Smith and 
Beck's, 158 

—achromatic, Euler on 145; Martin's 

lier’s, 146, 148; Selligue’s, 
‘Ross's early form of, 


— aguariom, 219-295 

— binocular, 61; Riddell’s, 97; Nachet’s, 
98; Chérubin d'Orléans’, 182; Wen- 
ham's stereoscopic, 98; Stephenson 
100, 895 ; Ross-Zentmayer’s, 178 
Powell and Lealand’s, 107, 178; Ross 
177; Rousselet’s, 200 

— chemical, Nachet’s, 216; Bausch and 
Lomb's, 217-220 


of 
892, 



























| — compound, 86, 89, 128, 197; construc- 





tion of, 89; path of light through, 40; 
Retzi on invention of, 127; Hocke’s, 
180; de Monconys', 180; Divini’s, 181 ; 
Janssen’s, 122 ;' Marshall's, ‘185 ; 
Hertel’s, 188; Martin’s, 189; Adams's 








INDEX 1081 


MOR 


ropoda, 859 
J on skeleton of pharynx 
in, 819 note; on Chiton's 


9 

of, wooden slides for 
0 

rl,’ 846, 

epidoptera 

875 

6 


977 





smostraca, 888, 889 
1 551 

+8, keeping, 458; labelling, 
‘ment of, 454 

891, 892 

James Smith's, 894 

4447 


; Muscular tis 


balsam, 449; in aqueous | 


in deep cells, 451 
Ophiurida, 450; Poly- 
i sponge - spicul 
stances, 45 

50; sections of 
ptera scales, 906; wings 
7a, 906; hairs of insects, 
insects, 910; blood, 962 
da baleam, 444, 449 
954-955; cartilage in ear 









A, of Hemiptera, 928 
938 
insects, 918 

retation of, 874, 875 
ehnia, 657; of Amada, 
lingeria, 683; of 
f Artemia, 884 ; of Bran- 
of fly on smooth surface, 
2 corpuscles, 961; of con- 
1e corpuscles, 965; of 
1% 490; of desmids, 510; 
598; of Navicule, 581; 
581; of Ciliata, 701 
heath of desmids, 510 
sation by, 575 





spores of, 669; epispores 


4, Langley’s method of 
9 é 

165, 966; capillaries in, 986 
, microscopic constitueats 


ferous tissue of, 620 

651 

the Radiolaria, 171; on 
ertines, 875 

3ommon Nervous System’ 
81 and note 

80 

ganiems, 651 

of Palmoglaa, 472; of 
W143 of Votoos, 488; of 
6; of Bacteria, 581; of 


; 861; of Amaba, 660; , 


NAI 


of Dallingeria, 688; of Hetcromita, 
685; of Tetramitua, 685; of Noctiluea, 
694 ; of Peridinium, 698; of Suctoria, 

8, of Citiata, 704 
ultiplying power of eye-piece, 240 

Munisr Chalmas and Schlumberger on 
dimorphism of Foraminifera, 727 

Munier-Charles on certain fossil Fora- 
minifera, 493 

Muricea elongata, spicules of, 804 

Musca, eye of, 911; antenne of, 919 

— vomitoria, eggs of, 980 

‘Muscardine,’ 578 

Musci, 594-599 

Muscinea, 598 

Muscle-cells, 975 

Muscular fibre, 972 ; structure of, 978; 
capillary network in, 986 

» preservative for, 443 

, OTA 











yo de hot 
[us le microscope, 184 
Mussels. See Ononele and Mytilacea 
Mya arenaria, hinge tooth of, 848 
Mycele of Fungi, 562; of Ustilaginea 

565 
Mycetoroa, 568 

jliobates, tooth of, 949 
yobia, 982; legs of, 984; maxillm of 
9 


wectice, 987 
ites, legs of, 984 ~ 

fyophan layer’ of Porticella, 701 
Myopy, 190 
yriophyllum, » good weed to collect, 
458 

Mynroropa, hairs of, 904 

Myriothela, intracellular digestion in, 
787 

Mytilacea, sub-nacrecus layer in, 48 
ytilus for observation of ciliary motion, 


Mycomabe, 304 564 

Myzogastret, 568 
fyzomycetes, 509 note, 568 ; 
ment of, 568, 568; spores “seo; 565; 
swarm-spores of, 568 ; ity with 
Monerotoa, 658 

Myzxosporidia, 614, 677 








N 


Nachet on ‘immersion system,’ 27; his 
binocular, 95, 98; his stereo-pseudo- 





scopic microscope, 208; his 
nose-piece, 248 
Nacreous layer in molluscan shells, 848, 
846, 848 
Naggeli and Schwendener on microsoopi- 
8, 67 





Naile, 958, 957 
Nais, 879 





INDEX 


NUD + 
Nediursoste, 3 nidamentum of, 858; em- 


Numerical aj pectin 29, 68, 60, 888, 867 ; 
formals for, 888; problema on, 864 
— — ot Ze tic series of 
Sietiret 185 of dry cbjoctive, 894; 

ter-immersion, 884; of oil-im- 








- Trane, ‘737 
— garansensis, 757 





of, 725 
Nummalitic limestone, 768, 760, 1007, 


Napher uaa parenchyme, 613; stellate 
calls of, 612 

Nymph of Acarina, 988 ; of Oribatide, 
‘988 


oO 
Oak, size of ducts in, 624 


— galls, 997 
Qberhtuecr’s spiral fine adjastment, 161 
Object-glass of compound microscope, 
38, 80; of long focus, 40; of short fooas, 
objen copecity ewer of, 44 
ject; if of, 
ree ening’ BIS; Abe's method of 
testing, 826-898;' diaphragms for use 
in testing, 829; Tripp's method of 


testing, 880 
Object holder for Thoma’s (Jung's) mi- 
crotome, 








changer, Zei we, 248, 264 
Objectives, achromatic, 19, 82; aplanetic, 
19; spochromatic, 19, 80, 84, 80, 211; 


20, 21; immersion, 28, 84, 





aperture of, 44; comparison of, 46; 
illuminating power of, 54 
mersion v. dry, 54, 79 ; dry, 





mounted objects, 55; dry, 68; dry, for 
study of life-bistories, 81; penetrating 
power of, 88, 886; sliding plate with, 
441; rotating disc with, 241; of wide 
spertare, 816; of small’ aperture, ex- 
‘amination of, 88; teste for, 889, 887; 
resolving power ‘of, and numerical aper- 


<= Tapio, 810; Wenham’s duplex 
front, 8: it's 58205 Reichert’ 









3 Ross's, 
805, 809 ; Bmith’s, 806, 809; "Wonham’s, 
810; covers for use with, 580 





1083 


OPE 


Objectives, apochromatic, 814, 815, 820 
immersion, Amici’s, 812; Toles’, 
812; Zeise’s, 818, 817 





’a, 810; boise’ 's, 817 

Oblique tiustination, 170, 171, 881 

— illuminator, 170 

Obliterntion of struoture by diaphragms, 


Occhiale, Galileo's, 124, 195 


Occhialino, Galileo's, 198, 126 
| sediments, 


Oceanic its, microscopic examina- 
tion of, 1014 7 
Ocelli of planarians, 871; of insects, 
Ocales of compound 
com; 
Seular, 40, 821; 9 ine. 


‘dogoniacea, 602, 50% 

Gidevonium ciliatum, 508 

Gnothera, pollen-grain, 646; emission 

llen-tubes of, 647; embryo of, 648 

Oil for immersion ‘lenses, suggested by 
Amici, 99 

— of cassia, used with Stephenson's 
illuminator, 265 

—_of cedar- wood, for immersion ob- 


8, 29 
oil ficeten 870, 871 
Oil-immersion, 29 
8, Amici’s, 819; Tolles’, 


— — objecti 
819; Zeiss, 817 
Oils, solvents for, 441 
Okeden on isolation of diatoms, 558 


note 
Oleander, epiderm of, 688; stomates of, 
Olivine, alteration of, 1001 





— corroded crystals of, 995 
Onehidium, oe eyes of, 865 
Oncidium, spiral cells of, 618 


Onion, raphides of, a1 ; 
(Ofgoies af auchersa, 492; of hero- 
plea, 601 Edogonium, on of 
Chara, 601% of Fucacea, B66, 687; 
of Peronosporea, 587 
Oilitie rocks, etrusture of, 1011 
Oooh in sens, B05 a 
eres, use of the term, 467 note; 
of Voluds, 484; of Faucheria, 402; of 
jheroplea, 801; of Gdogonium, 503 ; 
of Ohara Oty of t Phezosporea, 856; of 
of Marchantia, 698; 


OBepores, 470; of Volvoz, 484; of 
‘aucheria, 498; of Achlya, 495; 
800; of 











ot Spharoplea, sium, 
508; of Chara, 609; of Fucacec, 558 
Ooze, 'Globigerina, ot sin, 786, 
748; compared with 1007 
Opalescent mirror as a substitute for 
g prism, 179 
» | Opalina, 703 


jue illumination by side reflector, 
— monnte, 288 
‘Open’ bundles, 





1084 
f ork 
65; and Nuwnnewlites 
Opereulin, 73 1667/90 
Operculum nf momen, 5G 
Dpeacanhe, vita i CTU ANON ES 
Boy rece deal 3 
jars of, GO 
of, 601; pro- 


Opcdirie mine Spentapyltun, mpines of, 


mounting, 480 
ehitroudea ae welt oy 816; pines of 
815; teoth of, 81 ‘of, 895 
direct dew ont 
dia, quantities of, 
ria conten ta 108 
idiwm, cellulose in zoteytium of, 
7 
— versatile, éttect of light on, 702 
Opiryodendron, 697 
Opium poppy, latex of, 620 
‘Optic axle ef Powell and Loaland's Ne. 
1, 1745 of Baker's third-clnan, 19% 
Optical anomalies in petrology, 1002 





— centre, 44 5 
— tube-length of mi 

— tube-longth, Continent 
Omnls of Antedom, #25 


165 
166 


Orbiculina, 72%, 720, 78% 





60 
Orbitolina, 749 
ont ocourring with flint insta. 





ftatlaoe, 781 note, 738 

tonudasima, 733 

Orbulina, 745 

Orbaline shel, sandy isomarph of, 740 

Orchidecr, polliniam of, 64% 

Orchids, micropyle of, 648 

Orchts, pollon tubes ol 647; saods of, 
40 


ganised structure and living action, 


Ra minute, nucleus of, 80 
‘Organa, 463 
nk of sense * in Citiata, 702 note 
atid, nymph of, 988; mouth-parte 
of, 988; loge of, 934; integument of, 


juporocal glands of, 955 5 
; characters of, 006 








objects for sectionising, 
waloy's method, 416 
Orignmusn Oniter, seed of, 645 
Ornithorhyncus, hasr of, 954 

Orobanche soeds of 049 





INDEX 


PAP 
Orthoptera, eyes of, #11; antennm of, 
912; wings of, 0245 of, 988 
cme ‘Bameden's 

~e 

Orin Dekh, sporangia trestle 

Sector a meena at 

— movements of, 975 

cmp ‘nity wtrochuren, 429 
Ormunia, of, OL = 

— regaiis, yrothalliain of, €O4 note 
Ossein, of bone, 97 

Baines of “rhe 529; of 
weit faviculuces, pe 
Oatrucoda, a 

Ostreacem, shell of, 847 

ors of, 1081 


rasa 
Ororcortestea che ol tive, 20 
Over. 908 
‘Overton on Voleor, 484 note 
ear of ori 0 


sn 
Oran of Zydr70 
tricha, phase in development of 
honda, 
Ozywris vermigwlaris, 865 
Oysters, shell of, 847 


eu 

Patmallas a tsi of chen, 78 
— eruenta, 486 

Puedes ot frond of, 486 


rain marta okay ved 


Ncornes, antenna of, 912 
Zz ina, infested by Distorma, 870 
Pandorina, 475 


— morum, 
swarms} 


finder, M6 
Papaverncea, laticiferous tissae of, 690 


process of, 4855 


INDEX 


PAP 
Paper-cells, 386 
‘Parabolic illuminator, 267-269 ; reflector 
81; speculum, 281 

267-269 ; Edmunds’, 269 ; 
"Wenham's fiat-topped, 269 

Paraffin, solvents for, 417 

— for imbedding, melting point of, 417 

— cells, 886 

Paramecium, Cohn's experiments on, 
(668 ; contractile vesicles of, 704 

— aurelia, supposed sexual reproduction 
of, 710 

Paraphyses of Puccinia, 567 ; of lichens, 
578; of mosses, 596 

Parasites, nourishment of, 462 

Parasitic Crustacea, 889 

— Fungi, 562 

Parietal utricle, 468 

Parker (T. J.) on omic acid for Ento- 
‘moatraca, 428; on use of osmic acid for 
vegetable structures, 438; on Hydra, 
787 


Parkeria, 742 ; @ possible Stromato- 








646 

Passiflorea, pollen-grains of, 646 

Paste-worm, 869 

Pasteur’s solution for growing yeast, 574 
‘note; his experiments with Bacteria, 
587, 588 

Patella, shell structure, 852; palate of, 


855 
Path of ray of light through « compound 


mi (one 
Pathogenic bacteria, 585 
Pavement epithelium, 968 
Pear, constitution of fruit, 618 
“Pearl oyster’ See Meleagrina 
Pearls, 847 
*Pébrine’ in silkworms, 588 

, hair of, 954 


Pecten, prismatic layer in, 848; pallial ; 


eyes of, 864; eye of, 865; fibres of 
adductor muscle, 974 
Pectinibranchiata, 861 
Pectinide, oub-nacreous layer in, 848 
Pedalion, 718 
Boteuis’ 8107 cxperiments in, 87-4 
esis, 878; experiments in, 
Pediastrec, 196; affinitics of, 498 
Pediastrum, zovspores, 496, 497; micro- 
zodspores, 497 
— Ehrenbergii, 498 
= granulatum, 496, 497 
im, 497 
= tetras, 498 
Pedicellarim of echinids and asterids, 
818 
Pedicellina, lophophore of, 888 
Pedicularis palustris, 648 
— sylvatica, emabryo of, 648 
Peduncle of Lepas, 801 
Pedunculated cirripeds, 891 


1085 


PHI 
' Pelargonium, petal of, 448; pollen-grain, 
646 





Penerop! 
— variation in shape of shell in, 722; 
shell of, 724; varietal forms of, 728 
| Penetrating power, 867 
in objectives, 88; of objective, com- 
ith ilumimating power, 836 

Penetration, 88, 82, 88 

Penicillium, fermentation by, 575 

— glaucum, 671 

Pentacrinus asterius, skeleton of, 816 

Pentatoma, wings of, 924 

Peony, starch in cells of, 619 

‘Pepperworts,’ 606 

Perception of depth, 94 

Perch, scales of, 952 

Perforated shells of Brachiopoda, 850 

Perforation of shell in Foraminifera, 
‘794, 725 

Perianth, 648 

Perichlamydium pretextum, 715 

Poridinium uberrimum, 695 

Perigone of mosses, 595 

Periodic structures, 74 

Periostracum of molluscan shells, 846; 
of brachiopod shells, 850 

Peripatus, trachew of, 985 

Peritheces of lichens, 578 

Peronosporea, 567, 668 

Perophora, respiratory sac of, 889; cir- 
culation of, 889 

| ‘Perspicillum,’ Wodderborn’s, 127 
Potale, 643 








lum, eggs of, 988 

Be microscope, Swift's, 992 
etrology : micro-spectroscope in, 1008; 
‘micro-chemnistry im, 1004 

Pettenkofer's tent, 440 

Petunia, seeds of, 649 

Pesiza, botrytis-form of, 572 

Pfitzer, on roproduction of diatoms, 528 

Pheodaria, 777 

Pheosporea, 564, 555 

cytes, 961 note 

Phakellia ventilabrum, 782 

Phallus, 575 

Puaxzrooamia, woody structures, pre- 
aration of, 497 

—embryo-sac of, free-cell formation in, 
464-406 

— relation of, to Cryptogams, 607, 609; 
structure of stems, &c., 610, 625; struc- 
ture of cells, 612, 618; intermediate 
lamella, 618; intercellular spaces, 613 ; 
cell-wall of, 617; sclerogen, 617 ; spiral 
cells in, 618; laticiferous tissue of, 620 
mineral deposits in cells of, 620, 621; 
woody fibre in, 621 et 4¢q.; fibro-vas- 
cular bundles, 625; root, structure of, 
625; flowers of, 643; pollen-grains of, 
644; fertilisation of, 647; ovules of, 
647; seeds of, 648 

Phanerogams, See PHANEROGAMIA 




















Philonthus, antenne of, 912 





INDEX 


POL 


yrain and tube, 609 
1s, 644; form of, 645; experi- 
a with, 646 
+, of orchids, 647 

645, 
4, traced through the style, 647 
1m of orchids and asclepiads, 647 
ds of Floridea, 661; of lichens, 


al spicules, 788 

levigatus, 871 

nida, 887 

tina, 771, 772, 776 

ston of, 659 

itina,'as test for low powers, 
mounting, 450 

wmida, 905 

wtrica, Ehrenberg’s erroneous 
on, 678 

num, pollen-grains of, 646 
wphina, 745 

cmatus Argus, scales of, 900 

‘ies of zodphytes, 786 

vy of hydroids, 791 

4,787. See Hydroroa 

e, of Polyzoa, 829; formation of 
from, 880 si 

‘om of zodphyte, 838, 

¢, of hydraids, 701 

dium, sori of, 600 

ri BT isis 
chum angulare, apospory in, 

‘mella, shell of, 128 

iculata, 752, 758 

va, 752, 754, 765, 

Jamous Forami 
na uvella, life-history of, 684 
‘ma, 749; mode of growth com- 
with Eozodn, 768 

‘aceum, colour of, 724 

chum commune, 595, 596 

nua lagurus, heir of, 905 

air of, as test for objectives, 889; 

it for definition, 868 

1, collecting, 457, 458; keeping 
458; ‘cell’ of, 828; structure 

18; gemme of, 880; muscular 

m, 881; sexusl reproduction of, 
‘colonial nervous stem,’ 881 

tote; tresh-water, loy 

epistome of, 886; classification 
group, 888; bibliography of, 
elation’ to Brachiopoda, "881; 
of, 971 

ies in coralline crag, 1011 






















‘olin graine of, 647 
aticiferous tissue, 620; seed of, 


anea, 726-785 

ious ahells of Foraminifera, 
of Gastropoda, 858 

ritreous Foransinifera, difference 
5, 736 

ne, hair of, 954 

ft sponges, 780 





1087 


PRI 


Porphyra, trichogyne of, 561 
Porphyrtic crystals, glans inclosions in, 
7 


‘Portable’ microscope, Powell and 
Lealend’s, 198, 199; Beck's, 199, 203; 
Rouseelet's binocular, 200; Swift's, 
198, 200 

Portuna, skeleton of, 892 

Positive aberration, 809 note 





— eye-pieoe, 48 
= eye-pieces, 31, 829, 828 
Potash, caustic, action on horny sub- 





stances, 440 
Potato-disease, 568 
— starch-grains of, 620 
— tubers, starch in, 419 
Powell, Tr, formula for objective, 84 
Powell and Lealand’s he ii 





84, 85; high-power binocular, 107; 
sub-stage, 170, 174; their microseoy 
178, 189, 190; binocular, 17 
matic dry, 190; portable micron 
1098; rotating nose-pieces, 949; a:hro- 
matic condenser, 951, 267; new low- 
power condenser, 254; apochromatic 
condenser, 254; dry achromatic oon- 
denser, 258; chromatic oil condenser, 
258; condenser for polarisoope, 262; 
achromatic oil condenser, 968, 967; 
latest condenser, 267; bull's - eye, 
280; vertical illuminator, 2885; com- 









° scatlinstenan 3 water. 

immersion objectives, 810, 818 
inch objective, for observat * 
cyclosis, 614; objectives, for study of 
monads, 687 

Powell’s (H.) microscope, 152, 158; fine 
adjustment applied to the stage, 158 

= fine adjustment, 161 

Prawn, ekeleton of, pigment of, 898 

Prazmoweki and Hartnack’s water-im- 
mersion objectives, 810 

Preparation of vegetable tissues, 427 

Prosbyopy, 120 

Preservative media, 441-448 

issues of Vertebrata, 941 

PHmerdial colle, 465, 466 

— utricle, 468; of desmids, 510; of Pha- 
nerogam cells, 618 

— chamber in’ Foraminifera, 798; of 
Orbitolites, 781 

Primrose, cells of pollen-chambers, 645 

peaitogs feather,’ seed of, 648 
‘rinciple of microscopic vision, 48 

Principles of microscopical optics, 1 

Pringaheim on generative process of 
Pandorina, 486; on Vaucheria, 492 

Prism, refraction by, 8, 9; Wenham’s, 
‘99 ; ‘Stephenson's erecting, 102 

— polarising, substitution of opalescent 
mirror for, 172 

— rectangular, in place of mirror, 172 

— Nicol’s, 244, 269; Nicol’s analysing, 
925; Abraham's, 844 

— refracting angle of, 9, 18 








INDEX 


RAT 
tsand sponge-spiculescompared, 


estine, villi of, 986 

ales of, 952 

4, mode of labelling bottles, 845 
.ge, 14 note; formation of, 28, 24 
v image, 321 

osition of light by prisms, 18 
integument of, 898 

corpuscles of Vertebrata, 968 ; 
, in various Vertebrata, 959; re- 
sizes of, in various Vertebrata, 


801 
cles, flow of, 980 
ow,’ due to Palmella cruenta, 


der,’ 937 

ts in Infusoria, 702 

+, Sorby’s parabolic, 281 

day, 2 

ng angle of a prism, 9, 18 

on, 57 

of, 3 

nit, laws of, 2, 8 

ine surface, 8, 4; by curved sur- 
43 by prisms, &, 9; by lenses, 10 








ve index, absolute, 2; of water, 
lative, 4, 5; of crown glass, 5; 
t glass, 53 of balsam, 77; of gum 
+ 445 ; of Canada balsam, 445; 
lobromide of naphthalin, 445; of 
horus, 446 

ve index of sihcious coat of dia- 
445 

8 of air, of cedar oil, of water, 60 
r, Reichert’s, 898 

vs loups, 88; his objectives, 321; 
ermo-regulator, 893) 

r, huir of, 954 

ction in Actinophrys, 664 5 of 
oaplueriuin, 066; of Clathrulina, 
of Euglypha, 671; of sponges, 
of Campanulariida, 794 ; sexual, 
lyzoa, 881; agamic, of Entomo- 
1, 887; agamic, 930; of Acarina, 











tctive organs of Acurina, 985; 
tchnida, 985 

28, lucun in bone of, 946; cement, 
th’ of, 950, plates in'skin of, 950: 
smic ‘appendages of, 958; red 
corpuscles of, 958, 959 ; muscle- 
of, 978; lungs’of, 987 

seeds of, 640 

ry secondary spectrum, 313 
solvents for, 441 

ag power of objectives, 367 
object-glasser, 44; of lenses, 645 
jective and numerical aperture, 
6 

tion of insects, apparatus of, 918 
tory organ of Spier. 938 
comm, 966 

-a, calcareous polyzouries of, 888 
aria, 720 





1089 


R08 


Reticularia, charactersof, 658; examples 
of, 659-662 

Reticulated ducts of Phanerogams, 628 

Retinule, 907 

Revolving nose-piece, Nelson's, 244 

Rezzi on invention of compound micro- 
scope, 127 

Rhabdammina, 738 

— abyssorum, 740 

Rhabdolithus pipa, 771 

— sceptrum, 771 

Rhabdom, 007 

Rhabdopleura, 888 

Rhamnus, stem of, 628 

Rheophaz sabulosa, 740 

= scorpiurus, 740 

Rhinoceros, horn of, 957 

Bhizocarpece, 606 

Rhizoids of mosses, 594 

Rhitome of ferns, 600 

Runzopopa, 658-674, 770 

— protoplasm of, 461; ectosarc of, 464; 

sher's papers on, 677; Biitachli on, 
677 ; skeletons of, 720; sarcode of, 942; 
sudopodial network of, 977 

Rhizosolenia, 548 

= cyclosis in, 517 

Bhizostoma, 798, 800 

Rhizota, 717 

Rhododendron, pollen-grains of, 647 

‘Rhodospermece, 608 

‘Bhodospermin, 660 

Rhode a, 554 

Rhopalocanium ornatum, 778, 778 

Rhubarb, stellate raphides of, 621; spiral 
ducts of, 623 

Rhynchoglagellata, 694 note 

Rhynchonellide, shell structure of, 851 

Ribbons of sections, 408 

Ribes, pollen-tubes of, 648 

Rice, silicified epiderm of, 640 

* Rice-paper,’ 611 

Rice-starch, 620 

Riddell’s binocular microscope, 96, 97 

Ring-cells, 386, 387 

Rivalto (Giordano da) on invention of 
spectacles, 120 

Rivulariacece, hormogones of, 490 

Roach, sealex of, 952 

Rochea falcata, epiderm of, 689 

Rock, ground-mass of, 995; 
structure of, 996 

Rocks, method of making sections of, 
991; metamorphism of, 999 

Rodents, hair of, 954 

Roe-stone, structure of, 1011 

Root of Phanerogams, structure of, 625, 
636 ef eq. 

Root-cap, 685 

Rosalina varians, 723 

Rose, glandular hairs of, 639 

Rows’ (Andrew) on correction of object- 
glass, 10-21; his early form of achro- 
matic microseope, 150; mechanical 
movements of his stage, 151; his fine 
adjustment, 161, 161; on illumination of 
objects, 260; his arrangement for lock- 


4a 











fluxion- 











INDEX 


8cH 


ton binocular vision, 107; hiv 
adjustment, 160; his camera ' 
1, 286 
’s method of macerating vege- 
tissues, 625 ~ 
¢ (Prof, E.), his aquarium micro- 
222 
(Prof. Max) on identity of 
de’ and ‘ protoplasm,’ 460 note; 
‘closis_ in Diatomacee, 517; on 
‘y of Carpenteria, 747 

(Prof. F, E.) on soft parts of 
sctella, 785 note 
dener on lichens, 577 ' 
ada, 717, 718 | 
spring, 896 ; for section cutting, 





chyme of ferns, 600 
om, 621 
sin Fungi, 562; of Myzomycetes, 


ndrinm, indusium of, 600; sori 
d; sporanges of, 601 

ng, 881, 932 

ollur adjustment, 809 

daria, seeds of, 649 

stoma” of Cyanea, 799 

ma, ws gonid of lichen, 579 
mace, 490; hormogones of, 


shon, conjugation of, 556 
mone. See Actinia 
mones, intracellular digestion in, 


4,801. See Gorgonie 
lies," 777 
wax varnish, 384 
ts,’ 882. See Flustra and Mem- 
vora 
c eye-pieces, 823 
See Doris, Eolis 
808, See Echinus ! 
. 5 
auity of protoplasm in, 469 ' 
08 








ry minerals, 1001 i 
“im, 19, 31; overcome by Abbe’ 
iver, S14 

cutting, scissors for, 307 

4, 431, 432; cover glans as, 432 
ting, 447, \ 
, ribbons of, 408; of hard sub. | 
%, 420; of bonex, 420, 423; of 
420, 423; of enamel, 420; of 
. 420; of shells, 420; of teeth, 
23; of hard und’ soft substances 
er, 428; of Phanerogam tissues, | 


pollen-grains of, 646; seeds of, | 
19,648 

ation of Gastropoda egg, 859; of 

1 body, 872 

‘olution for cleaning slides, 380 
Ua, archegone of, homology of 


Uew, 607 


1091 
SHR 


Selective staining, 431 

— stains, 436 

Selenite, 270 

— with mica film, 271 

— stage, 270 

Selenites, 262; blue and red, 271 

Selligue’s achromatic microscope, 146, 
148; objectives, 308 

Semi-apochromatic objective of Leite, 
820 


Sempervivum, seeds of, 649 

Seneca, on magnifying by water, 190 
Sense, organs of, in Mollusca, 864 
Sensory nerves, 976 

—o1 of sponges, 780 

Se] 1S 






epia, pigment-celle, 866 

Sepioia, eggs of, 868 

‘Sepiostaire’ of cuttle-fish, structure of, 
858 ; imitations of, 1028 

Septa in shell of Foraminifera, 721, 728, 
729 

Serialaria, presumed nervous system in, 
881 


Serous membrane, 965, 966 

Serpula, tubes of, 872 

Serricornes, antenne of, 911 

Sertularia cupressina, 795 

Sertulariida, gonozodids of, 794; z0d- 
phytic stage of, 801 

Sessile cirripeds, 891 

Seta of Tomopterts, 877 

‘ Sewage fungus,’ 583 

Sexual fructitication, 470 

— generation of Volvoz, 488 

Shadbolt on structure of Arachnoidiscus, 
Bal 

Shadbolt's turn-table, 386, 391 

Shadow effects, 61 

Shark, dentine of, 947 

Sharks, scales of, 952 

‘Sheep-por, 588 

Sheep-rot, 860 

Shell, bivalve, of Ostracoda, 889 

— calcareous, of Reticularia, 658; of 
Microgromia, 661 

— ilicious, of Dictyocysta, Costonella, 
700 

— of Foraminifera, 721-726 ; of Lamel- 
libranchiata, 843; of Brachiopoda, 
BAB 

Shellac cement, protection against cedar 
oil, 884. 

‘Shell-fish,’ 843. See Mollusca 

Shells of Mollusca, nacreous layer of, 
843, 846, 848; prismatic layer of, 844, 
845, 847, 848; colour of, 845; an ex- 
cretory "product, 846 ; ' wub-nacreous 
layer of, 847, 848 

— of Brachiopada, 849; periostracum of, 
850; perforations of, 850 

— of Gastropoda, structure of, 852 

= of Cirrwpedia, #02 

«Shield of Cilidfa, 700 

Shrimp, concretionary apheroids in. skin 
of, 1021 

Shrimps, skeleton of, 498 





4a2 





INDEX 


SPH 


Spharria in caterpillars, 674 
;hceroplea annulina, 500, 501 
sheerozoema, rows of cells in, 512 
heeroroum ovodimare, 777 
jphagnacea, 598, 599 
Sphagnum, Veal of, 598 
Sphenogyne speciosa, winged seed of, 
649 
Spherical aberration, 14, 15, 81, 249, 
‘951, 254, 381 
—— diminished by Huyghens’ objective, 


43 
‘Spheroidal concretions of carbonate of 
lime, 1021 1 
Sphingida, antenne of, 913 
‘Sphinz, eyo of, 911; antenna» of, 912 
iguatri, eggs of, 929 








Spicales of aleyonarians, 604 
=o 


8, 772; their names, 783-784 
icious, of sponges, 781 
Srggleatecae of sponges, el 
‘Spiders, 881, 982, 988; microscopic objects 

‘furnished by, 988 ; ‘spinning apparatus, 


989 

‘Spinal cord, Hill's method of preparation 
‘of, 484 

Spindle fibres, 468 

‘Spinnerets of spiders, 989 

‘Spiny lobster, metamorphosis, 898 

Spiracles of insects, 919, 920 

‘Spiral cells in Phanerogams, 618; mode 
of preparation of, 619 

— crystallisation, 1018 

= focussing for projection-lens, $24 

—vessele of Phanerogams, 622, 628 ; 
observation of, in situ, 644; of plants 
compared with trachew of insects, 919 

Spiriferide, pertoration in shells of, 851 

Spinyerina ‘rostrata, shell of, 851 

Spirillina, 744 

— sandy isomorph of, 739 

Spirillum, movement of, 875; granular 
spheres of, 588 note 

— undula, 586 

— volutans, movement of, 581, 588, 586 

Spirit, dilute, as a preservative medium, 
442 

Spirocheete, 581 

‘ogyra, 478 ; attacked by Vampy- 

ella, 654 

Spirolina, a varietal form of Peneroplis, 
728 

iroloculina, 727 
Spirula, 858 

— shells of, bearing Protomyzxa, 65 

Spirulina, movement of, 490 

Bplachnum, sporange of, 504 

Splenic fever, 588 

— due to Bacillus anthracis, 682 

Sponge-spicules, 781-784 

— mounting, 450 

— in Carpenteria, 747 ; in mudof Levant, 
1007 

‘Sponges, 779-786; skeleton of, structure 
of, 779, 780; reproduction of, 761; 
habitat of, 785; preparation of, 78! 
186 ; bibliography of, 786; pseudopodi 

















1093 


STA 


of cells in, 786; intracellular digestion 
in, 787; fresh-water form of, 787 

Spongilla, 785 

Spongolithis acicularia, 550 

Spongy parenchyma of leaves, 641 

Spontaneous generation, 686 

Sporange of Fungi, 562; of Marchantia, 
590, 598; of mosses, 596; of Sphag- 
nacee, 699; of ferns, 600; of Equise- 
tacea, 605 ; of Myzomycetes, 565 

Sporangia of Lycopodiacece in coal, 1006 

Sporangiophores of Mucorini, 569 

Spore, use of the term, 487 note 

Spores of Nostoe, 491; of Myzomycetes, 
568, 565; of Pe ore, 568; of 
Bacteria, 687; of Marchantia, 598; 
of mosses, 597; of ferns, 601; of ferns, 
method for studying development of, 
604 note ; of Equisetacea, 605; of 
Lycopodiew, 606; of gregarines, 675; 
of Monas Dallingeri, 682; of Lycopo- 
diace@ in coal, 1008 

— different kinds of, 470 note 

‘of Chetophoracec, 588 

Tatilaginee, 565; of Puccinia, 











Spori 
566 

Sporocarp of Ascomycetes, 572 

Sporogone of mosses, 597 

Sporophores of Myzxomycetes, 565; of 
‘Peronosporea, 568; of Ascomycetes, 
871 

Sporophyte in ferns, 605 

‘Sporozoa, 674-677 

Sporules of Melosira, 526 ; of Pleuro- 
‘tigma, 526; of Podosphenia, 526 

Spot-lens, 267 

Spring-clip, 394 

— press, 894 

— scissors, 896 

‘ Spring-tails,’ 908. See Poduride 

Squid, 866 

Squirrel, hair of, 954, 955 

Stag-beetle, antenne of, 912 

Stage, horse-shoe, Nelson's, 168, 190; of 
the’ microscope, 165-168; concentric, 
rotatory motion of, 167 ; qualities need- 
ful in a, 167; in Hartnack’s model, 
211; mechanical, 215; graduated 
rotary, 888 

— -forceps, 287 

— -micrometer, 226, 280, 289, 240 

— moist, 290 

= piste. glass, 288 

— thermostatic, 292, 298 

—Turrell’s, 165, 189; Toller’, 166, 184 ; 
Zeixe’s, 167 

— -vice, 287 

‘Staggers’ of sheep, due to Canurus, 86s 

Stahl on movement of desmids, 510 


| Staining, process of, on glass slides, 480, 


481; multiple, 488; double, 488; me- 
thods, 480; differential, 489 

— Bacteria, 487, 488 

— fluids, 482-487 

— procenses, 480 

Stains, violet of methanilin for Bacteria, 
487; methyl-blue for Bacteria, 688 





1094 
ont 
1 
‘Stains, pein blue, 
Staphytomns, antanst of, $2 
Bika tae of testa, mi 617; testa 
of weed of, 


AH ape of, = 





Tite of at: an in” Goma val in | 


potato, 120; in wheat, 6205 in rice, 


eu 
* pie! Ash, &hS. See Anteroiiden 
of Protompes, 858 
Blowtarum, Giuary division of; B19; 
fori of cell, 515 
siactam, 198 


romess, G46 
*Stauros’ of Achmanties, G4 
Steenstrup on alternation of genernticos, 


Stein on affinities of Voleor, 470; on 
contractile vacuoles of Volwow, asl 
note; on Plagellata, 080 Not 
Tuea, (4 note; on Acinet i, 690 note 

Steinheil’s loups, 48; his combination of 
Tenses, 88; his aplanatio longs, 206; hin 

p for tank work, 284; his formule 
combination of lente, 816; hit 
triple loups, 322 
tellaria, gor of, G40 

— metia, patalsot, 4d 

Stem of mosses, SUL; of Brymeese, 585 
. Of Sphagnacesr, S08; structure of, in 

mins, 025; of rogatnia, 
development of, G04, 636; trextment of, 
for examination of their structure, 636, 
aT 

Stemmnta of insects, 910; of spiders, 988 

Stentor, collecting, 457; improssionable 

‘contractile vesicle of, 

conjugation of, 711 

eros, collecting, 487; in oom: 

inement, 458 

Stephanolithis epinescens, 772 















704 
Steph 


 amebiform 





Staphenson ou Plewresigma angulatwm, 

WD: on “intercostal pointas 7S, 

— hiv suegnetion on, homogentoas Se 
me 

— on Coxcinodiacas, 588 

Stephenson's binocul 
stage condenser, 10 
Ine, 102; erecting 
dioptric iluminator, 170, 208, iors 
dissecting mieroeoope, 201, 203, 405; 
tank microscope, 220 

Sterecoaulon rameloeus, 679 

Sterempsendoscopic microscope, Na- 
thot 208 

Sterwoscope, 00; Brewster's modiflention 
of, 

Stareoscopic binocular, Wenham's, 98; 
for study of opaque object, 108, 107 
— aye-piece, Ab) 

— vision, 89-05 












100, 344; sub- 








introduction of, 87; in the 
ees te 26t, 203 Pee 


Sirgpontetr porta setioas ta abatla ct, 





Statodyer ruc ITE 
Sthmeteo layer in mollusean shells, 
Bi ieee, 100-1 Nelson's to 
waa ee ional and ta tas: 
154s edunayers Siodal Tt 
ia bee =e. Tel; centring 
nose 
‘Sabatage Neleon’s, tH: 
Spier wi; Sea ™ 
-1 
_ lest form of, 262 
Sannin teshs Siete set 
Sucker on of 
Suckors on fot of Dytigews, DB} of Cwrs 
culionmide, 996 
Swetorin (Protaroa}, 006-809 
TBagertonte: P01 Bee 
“Tone 
Sulphuric acid, as a ee 
‘Sun. ‘animaloul 
“Sundew,’ glands of, 689 
Sunk. cella, 8 


INDEX 


SUP 


Super-amplification, 33 


Super-stage, 169 
Supplemental yolk in Purpura, 862, 863, 
981 


Surirella, 518, 585; conjugation of, 528 ; 
rygospores of, 529; movements of, 581; 
frustule of, 535 

— biseriata, cyclosis in, 517 

— caledonica, 551 

constricta, 586 

— craticula, 551 

— plicata, 551 

Surirellea, 585 

Suspensor of ovule of Phanerogams, 464 

Sutural line of desmids, 590 

Swarm-spores, 466; not a new genera- 
tion, 467; meaning of term, 470 note; 
of Pandorina, 485; of Hydrodictyon, 
495; of Cutleria, 556; of Clathrulina, 
667; presumed, of Pelomyza, 670 

Bweat- da, 966 

‘Sweetbread,’ 971 

Swift's side-lever, 158; vertical side- 
lever fine adjustment, 162,181; micro- 
scopes, 181, 190, 194, 197; portable 
mi , 198; low-power condenser, 
952; condenser for polariscope, 262; 
sub-stage illuminator, 271; micro: 
spectroscope, 275; live-box, 295; petro- 

ical microscope, 993 

Symbiosis in lichens, 578 

Symbiotes tripilia, hairs of, 984 

Symbiotic alge in radiolarians, 778 

Sympathetic nerves, 978 

Symphytum asperrimum, weeds of, 049 

jynalissa symphorea, 579 

Synapta digitata,‘ anchors of, #19 

— inherens, ‘anchors’ of, 819 

Synapta, rotifers in, 718 

Syncoryne Sarsis, gonozovids of, 792 

ry ta, 475, 

Synedra, 685 

Syringammina, 786 

Syringe for catching minute aquatic 
‘objects, 800 

Syrup, ss « preservative medium, 442 


4438 








T 


Tabanus, 911; ovipositor of, 927 

Tabellaria vulgaris, 551 

‘Table of numerical apertures, 84-87 

— for microscopists, 841-845; for dis- 
secting and mounting, 842 

Tactile papille of skin, 966; nerve to, 
a7 


‘Tadpole, pigment-cells of, 967; circula- 
tion in tail of, 980; general circulation 
in, 081; blood-vessels of, 985, 984 

— of ascidians, 641 

Tadpole’s tail, epithelium of, 968 

Tenia, 867 

Tank microscopes, 219-225 

Tannin, test for, 440 

‘Tapetal cells in fern antherid, 608 








1095 
THA 


‘Tape-worm,! 867 

Tardigrada, desiccation of, 89 

Tarsonemide, 987 

Tante, organs of, in insects, 917, 924 

Teeth, decalcification of, 426 

— fossilised, 1012 

— in palate of Heliz, 854; of Limaz, 
854; of Buccinum, 854; of Mollusca, 
854 

— preparation of, 947 

— of Echinus, 814; of Ophiothriz, 816; 
of Vertebrata, 047 

— of elephant, Rolleston on enamel in, 
852; of Rodentia, Tomes on enamel in, 
862 

Tegeocranus cepheiformis, 982 

= dentatus, 932 

Tegumentary appendages of insects, 098 

Telescope, Barker's Gregorian, 144 

Teleutospore generation of Puccinia, 
566 

Temperature, effect of, 
monads, 686 

Tendon, 948 

Tentacle of Noctiluea, 601, 602 

‘Tentacles’ of Drosera, 689 ; of Suctoria, 
697 ; of Hydra, 788; of annelids, 878 

Tenthredinide, ovipositor of, 927 

Terebella, tubes of, 872; gills of, 873 

= conchilega, 872 

Terebratula bullata, shell of, 851 

Lerebratule, shells of, 849, 850 








on various 





\ Terpainoé musica, 587 


Terpainoce, character of, 587 

Tertiary tints in crystalline bodies, 1014 

Tenselated epitheliam, 968 

Test of Gromia, 680; of Arcella, 670; 
of Diflugia, 671 

Testa of seeds, 649 





| Testaceous amcebans, 670, 671 


‘gum, as a preservative medium, , 





Testing object-glasses, 325; diaphragm 
for use in, 829; Fripp’s method, 830; 
Abbe’s method, 826-383 

‘Test-plate, Abbe’s, 380, 881 

Tests, sandy, of Lituolida, 789 

Tethya, wpicules of, 1008 

Tetramitus rostratus, life-history of, 
685 ; nucleus of, 688 

Tetranychi, 987 

Tetranychus, mandibles of, 988 

Tetraspores of Floridec, 661; of Vam- 
pyrella, 655 

Teztularia, 248 

— aculeata, in chalk, 1008 

— globulosa, in chalk, 1008 

‘Textularian form of shell, 728 

— series, 748 

Textulariide, 786 

Textularini, arenaceoux character of, 
748 

Thalassicolla, 772, 777 

Thallophytes, 467, 470 

Thallophytic type, passage to cormo- 
phytic, 594 

Thallus of Ulva, 488; of Phaosporecr, 
555; of lichens, 677 

Thaumantias Eschscholteii, 797 


3 a ay wae 
batt ttt He wine 


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INDEX 


UNG 


‘Unger on the zoispores of Vaucheria, 
492 

Unicellular plants, 469 

Unio, pearls in, 847 ; glochidia of, 857 

— oceidens, formation of shell in, 849 

Unionide, nacreous layer of, 847 

Unit (standard) for microscopy, 400 

Uredinee, 565 ; alternation of genera- 
tions in, 565 

Uredo-form of Puccinia, 567 

Uredospores of Puccinia, 567 

Urinary calculi and molecular coalescence, 
1023 

Urine, micro-chemical examination, 1034 

Urochordata, 835 

Uropoda, trachem of, 985 

“Urticating organs.’ ' See Thread-cells 

Ustilaginee, 565 

Uvella, 475 


v 


Vacuoles in cell, 464 

—contractile, in protophytes, 465; of 
Volvoz, 481 

of Actinophrys, 662 

‘Vagine of mosses, 596 

Valentin’s two-bladed knife, 898 

Vallisneria, habitat, 618, 614; mode of 
demonstration of cyclosis, 618, 614 

Vatvulina, shell of, 728 

Vampyrelia, 654, 655 

— gomphonematis, 655, 656 

— spirogyree, 654, 655 

Vanessa, 911; haustellium of, 916 

— urtice, eggs of, 929 

ion, range of, in Aatromma, 774 

Varley’s 

Varnish, test for, 383; asphalte, 383 

Varnish 
‘384; red, 385; white, 385; various 
colours, 345 

‘Vascular Cryptogams,’ links with Pha- 
nerogams, 607 

Vascular papillee of skin, 966 

Vaucher, on Siphonacee, 492 

Vaucheria, 491-493 

— Rotifera in, 713 

‘Vegetable ivory,’ endosperm of, 618 

Vegetable substance, preparation of, 
427; gum-imbedding for, 427; bleach: 
ing of, 427; Cole’s staining method, 486 

= structures, hardened in osmic acid, 428, 

Veins of vertebrates, 980 

Velum,’ in gastropod larva, 860 

Venice’ turpentine cement, for glycerin 
mounts, B84 

Ventriculites, 785, 1010 

Venus’ flower basket, 788, 784; spicules 
of, 784 

Verbena, seeds of, 649 

Vertebrata, 835; bone of, 944; teeth of, 
947; dermal skeleton of, 950; blood 

of, 958: red blood-corpuscles, 95H; 

white blood-corpuscles, 960; distribu- 

tion of ciliated epithelium, 968; kidney 

of, 971 
























1097 
WAR 
Vertebrated animals, 941 
Vertical illuminator for ascertaining 
‘aperture,’ 206 
Vespida, 911 


Vibracuia of Polyzoa, 834, 835 
Vibrio, movement of, 875 
— rugula, 586 
“Vibriones,’ as applied to certain nema- 
todes, 869 
Vibriones, form of, 581, 586 
, Vigelius on tentacular cavity of Polyzoa, 
829 note 
| Vignal on oamie acid for Noctiluea, 428 
Vine, size of ducts of, 628 
Viola tricolor, pollen-tubes of, 648 
Violet, cells of pollen-chamber, 645 
— of methanilin, for staining Bacteria, 
487 
Virginian spiderwort, cyclosi 
616 
Virtual image, 14 note, 24, 25, 821 
Vision, depth of, 88, 89, 90; stereoscopic, 
89 
Visual angle, 27 
Vitren (Foraminifera), 744 
Vitreous cells (arthropod eye), 907 
tical compounds, 81 
ells of Foraminifera, 794 
‘Vittee’ of Licmophorec, 584; of seeds 
of umbellifers, 649 
Voeal cords, structure of, 964 
Vogan’s changing nose-piece, 244 
Volcanic ashes, microscopical examine. 
tion of, 101 
— dust, examination of, 999 
Volvocinea, 479-485 
Volvor associated with Astazta, 690 
— vegetable nature of, 484 note; amoe- 
biform phase of, 485; Rotifera in, 713 
— aureus, cellalose in, 481; starch in, 481 
— globator, 479-485; flagellate affinities 
of, 479; contractile vacuoles in, 481; 
endochrome of, 482; multiplication of, 
483; reproductive cells of, 488, 484 
Vorticella, foot-stalk of, 701; contrac- 
' ‘tion of foot-stalk, 702;' fission of, 704; 
gemmiparous reproduction of,’ 711} 
conjugation of, 711 
= microstoma, encystinent of, 706, 707 
Vorticellina, encystment of, 706 





in, 615, 








w 


Waldheimia australis, shell of, 850 

Wale’s coarse adjustment, 185; his fine 
adjustment, 185; his limb, 185, 189 

Wallftower, pollen-grains of, 647 

Wall-lichens, 57 

Wallich, on structure of diatom frustule, 
519 note; on Triceratium, 548 note; 
on Chetoceree, 644 note; on cocco- 
spheres, 672; on Polycystina, 776 note 

‘Wallich’s plan for sectionising a number 
of hard objects, 421 note 

«Wanghie cane,’ stem of, 626 

| Ward’s simple microscope, 205 











INDEX 


z00 





lew, 581 

IPHYTES, 786-807 

— mounting, 388, 389 

— non-sexual reproduction of, 980 

Zoiiphyte troughs, 297, 298 

Zoiisporange of Volvoz, 488, 485 

Zoiisporanges of Pheosporec, 556 

Zoiispores, 468; of Palmoglea, 472; of 
Protococcus, 474, 475; of Palmodie- 
tyon, 487; of Ulva, 488 ; of Vaucheria, 
492; of Achlya, 494; development of, 
494; of Hydrodictyon, 495; of Con- 
Servacea, 500; of Gdogonium, 502; 
‘of Chetophoracea, 508; of Chytri- 
diacee, 555; of Phaosporee, 550; of 
Floridee, 561; of Fungi, 562; of 
radiolarians, 73 

Zoiithamium, collecting, 457 











1099 
zyM 


' Zodxanthelle in radiolarians, 78 
Zoizygospores of Navicula, 526 
Zukal on movement of Spirulina, 490 
Zygnemacee, characters of, 477; habitate 
‘of, 477; conjugation of, 478 
Zygosis in Actinophrys, 665; of Ameba, 
669 ; of gregarines, 677 


Zygospore, 487; formation of, 170; of 
lydrodictyon, 495; in Desmidiacea, 
518, 514 


Zygospores of Palmoglera, 472; of Meso- 
carpus, 478; of Spirogyra, 478; of 
Pandorina, 485; of Ulva, 490; of 
Navicula, 526; of diatoms, 528; of 
Mucorini, 569 

Zygote of Glenodinium, 695 

Zymotic or fermentative action of Fungi, 
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WHITE AND WILCOX. Materia Medica, Pharmacy, Pharmacology, and 
Therapeutics. A Handbook for Students. By WM. HALE WHITE, M.D., F.R.C.P., 
etc., Physician to and Lecturer on Materia Medica, Guy's Hospital; Examiner in 
Materia Medica, Royal College of Physicians, London, etc. ‘American Edition. 
Revised by REYNOLD W. WILCOX, M.A., M.D., Professor of Clinical Medicine 
at the New York Post-Graduate Medical School and Hospital; Assistant Visiting 
Physician Bellevue Hospital. Cloth, $3.00; Leather, $3.50 

WILSON. Handbook of Hygiene and Sanitary Science. By GEORGE WILSON, 
M.A., M.D., F.R.S.E., Medical Officer of Health for Mid-Warwickshire, England. 
With Illustrations. Seventh Edition, Enlarged by 200 pages. 12mo. Cloth, $3.25 

WILSON. The Summer and its Diseases. By James C. WILSON, M.D., Prof. of the 
Practice of Med. and Clinical Medicine, Jefferson Med. Coll., Phila. Cloth, .50 

WILSON. System of Human Anatomy. 11th Revised Edition. Edited by Henry 
EDWARD CLARK, M.D.,M.R.C.S. 492 Illustrations, 26 Colored Plates, and a 
Glossary of Terms. Thick 12mo, Cloth, $6.00 














Potter. A Compend of Anatomy. 
16 Lithograph Plates. 117-other | 


INCLUDING THE VISCERA. (Based on Gray.) By Samu. O. 
late A. A. Surg. U. S. Army ; Professor of the Practice of Me 
College, San Francisco. Revised and Enlarged. 12mo. 
Compend ? Series. See page 29. Strong}: 
Interleaved, for the < 
+,* An Appendix has been added to this edition, containing 16 Lithograph 
Nervous Systems, with explanatory tables that will be found exceedingly usefu 
call special attention to these tables, as being entirely original in design and 
of the most difficult part of Human Anatomy, and including anastomo: 
jon (the arteries and nerves); a thing never before shown completely in tabul: 
so arranged as to grade the branches according to relative importance, and by 
of brackets with various types, the tables are veritable pictures themselves of | 
Dr. Potter's pewer of condensation and arrangement, have never been displ 
~« tables, which must take their proper place as the best of all attempts of th 
ce of pages the size of which was previously determined, and to which the tab 
The plates are equally original, having been made from new drawings by 1 
craphic delineations, and being diagrammatic, do not represent the exact forn 
~ shown. If colored by hand, by the student, as may be done with very littl 
ly increased. 








“In the particular line to which it belongs, and as one of the pioneers, this 
stands in the list of the very best. This is particularly conspicuous in ¥ 
er the sobject of anatomy attractive when presented in compends.”—d meri, 
January, 189%. 
“This is ? Quiz-Compend No. 1, based on Gray principally, and is a book 
sity, and to the practicing physician a great aid as a ready reference wot 
nce, to keep in mind a great many valuable points in anatomy that otherwise | 
nati Medical Journal, February 15th, 1897. 
Of all the’ studies in a medical course, anatomy is the most important. Tc 
ivw, is very irksome, and by having an Anatomy in an epitomized form and t 
1 labor will be saved. Dr. Potter has thus conferred a boon on both the stude 
uilishing his Compend of Anatomy. The tables and plates of the nerves and 
institute the Appendix, and by their aid one can review this important part of 
ne." —-Canada Lancet, Toronto, February, 1891. 








Robinson. The Latin Grammar of | 


Medicine. 


By H. D. Rosinson, PH.D., Professor of Latin Language an’ 
of Kansas, Lawrence. With an Introduction by L. E. Say 
Pharmacy, and Dean of the Dept. of Pharmacy, in the Unive 
275 Pages. 


“Tt is a work that meets with my hearty approval. There is great neec 
rican schools of pharmacy and medicine.”—Z. S. Bastin, Professor of 1 
hwestern University, Chicago. 

* The object of this uscful book is a very laudable one, namely, to improve, 
both physicians and druggists, chietly in the prescribing of drugs. While it is tru 
hod it unpecessary to remember the genitive endings of words used in medici 

vintions in prescribing-writing, there are others who frequently desire to 

‘ggist in Latin, in order that the patient may not learn of facts about which it 

n in ignorance. We hope that the book will prove a success, and by its 

rmaceutical and medical schools, improve the knowledge of Latin in both 

» Philadelphia, January roth, 1891. 

“The plan of the book is excellent, the field new, as it fills a long-felt 

should have it, both the collegian, as it will give a practical tum to his knowl 

uate, as it will give him a direct and useful acquaintance with that languag 
has not had the advantages of the younger men will find it a great help in over 
peedily acquire a familiarity with this \onguage that will surpiar bis classica 
joner, December, 1890. 

















A HANDBOOK 


Local Therapeutics 
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Hospital ; Demonstrator of Osteotogy, University of Pennsylvania; and Arthur Van 
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In One Handsome Compact Volume. Cloth, $4.00 





ANNOUNCEMENT. 


The importance of the local application of simple remedies in slight ailments of 
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