JuLy 25, 1912] 
NATURE 525 
MICROSCOPY. 
(1) Modern Microscopy. A Handbook for Begin- 
ners and Students. By M. I. Cross and M. J. 
Cole. 4thedition. Revised and enlarged. Pp. 
XVii+ 325. (London: Bailli¢re, Tindall and Cox, 
1912.) Price 6s. net. 
(2) Wirkungsweise und Gebrauch des Mikroskops 
und seiner Hilfsapparate. By Prof. W. 
Scheffer. Pp. vii+116. (Leipzig and Berlin: 
B. G. Teubner, 1911.) 2.40 marks. 
(3) How to Use the Microscope. A Guide for the 
Novice. By the Rev..C. A. Hall.’ Pp. viii+ 
88+ plates. (Londonw A. and C. Black, 1912.) 
Price 1s. 6d. net. 
(1) HAT a book on microscopy should reach 
a fourth edition, although the first was 
written some eighteen years ago, says much for 
the information it contains, and is sufficient indica- 
tion that it has taken its place among the literature 
of the subject. It is intended, at least primarily, 
for the amateur worker, and for such the descrip- 
tion of apparatus and methods of using it are 
lucidly set out. 
Important as the amateur may still be, he is in 
point of numbers far outstripped by the profes- 
sional, to whom the microscope is a necessary tool 
in constant use from day to day, but who none the 
less needs a knowledge of the principles governing 
the use of the instrument to enable him to get the 
best results. This knowledge is in too many cases 
sadly wanting, but a careful perusal of this book 
and application of the information given will 
remedy the deficiency. No space is wasted on 
mere catalogue eulogy, the main points of the 
instrument, both from a mechanical and optical 
point of view, being indicated. It is interesting 
to note that the student is advised to give pre- 
ference to a-microscope of English manufacture 
where work of a critical nature is contémplated, 
as in the best of these is to be found that com- 
bination of adjustments that the critical worker 
needs. This advice is in agreement with the 
opinion of the majority of leading microscopists in 
this country. 
Perhaps the most important part of the book is 
that devoted to the preparation of microscopic 
objects, and to ensure that the information is 
thoroughly trustworthy, the cooperation of a 
recognised expert has in each case been secured. 
The result is that a clear, short, and lucid descrip- 
tion of the chief processes involved in each branch 
of microscopic science is provided. 
The book may be cordially recommended to the 
student who desires to acquire a good general 
knowledge of microscopic technique. 
(2) The book by Prof. W. Scheffer is intended 
as a guide to those who are unacquainted with 
NO. 2230, VOL. 89] 
the use of the microscope. Perhaps for its sizé 
it covers too much ground to fulfil its purpose 
efficiently, and the subject is not so simply dealt 
with as the author apparently intends. It is a 
book of considerable interest to those who already 
have a good knowledge of the subject, but, at 
least for English readers of the class for which 
it is written, it would not prove to be a simple 
handbook and guide. 
The opening portions are devoted to an exposi- 
tion of the optical theory of the instrument, which 
is dealt with in a thorough and interesting manner 
without the use of higher mathematics. A slight 
technical error occurs on page 15, Fig. 10-3. The 
figure is intended to show the utmost resolution 
that can be obtained with oblique light. In such 
a case the chief and the first maximum in corres- 
pondence with one another, which are necessary 
for resolution, would be contained in similar halves 
of the circle. 
On pages 54 and 55 are to be found an exposi- 
tion of the usual views held in Germany, as well 
as the misunderstanding, as to the function and 
use of sub-stage condensers. It is implied that 
aplanatism and achromatism are only necessary 
in general if the source of light is small, and that 
the use of a large light source makes up for this; 
a conclusion that is, to say the least, misleading. 
It is interesting to note that the use of wide 
illuminating cones is distinctly favoured, and that 
the advisability of having a centring arrangement 
to the sub-stage is admitted, both points indicating 
that the usual German disregard of such arrange- 
ments is perhaps weakening. 
The description of the Abbe diffraction apparatus 
is most interesting, and the methods of carrying 
out the experiments are concisely stated. The use 
of dark ground illuminators is described, together 
with the effect of over and under correction, when 
using such appliances. The book is, in general, 
most interesting, and is written on scientific lines. 
It fills a place in the literature of the subject that 
no English work can claim to have done exactly 
in the same way. 
(3) There are several books available to those 
who have practically no knowledge of the micro- 
scope and its use, but the one now under notice 
may reasonably claim to be the simplest of them all. 
The expressed intention is to indicate the general 
ideas governing the use of the instrument; and 
with a view to simplicity, the instructions given 
are only in reference to low and medium power 
work. It is to be regretted that in some cases 
there is a want of accuracy of expression which 
might easily have been avoided, and that even the 
plea of simplicity cannot justify. For instance, 
we read, when speaking of the effect of alteration 
