OCTOBER 20, 1899. ] 
related phenomena, as displayed in the history 
of the germ-cells and in the early stages of 
embryological development. This tendency of 
cell-research, with which students of cytology 
are sometimes reproached, is not wholly due to 
the high theoretical interest of the germ-cells. 
It is in large measure a result of purely practical 
conditions, such as the large size of the cell- 
elements in germ-cells or embryonic cells, the 
ease with which they may be obtained in all 
stages of development, and the accurate control 
of results thus rendered possible. Similar 
reasons may be given for the large share of at- 
tention that has been devoted to special forms 
of tissue-cells, such as the epithelial cells and 
leucocytes of salamander-larvee, or the embry- 
onic cells of plant-tissues. Cytological teach- 
ing has inevitably followed in the main, the 
lines of research ; and thus it has come to pass 
that in practice, courses in cellular biology 
cover a very different field from those in histol- 
ogy, requiring special material and employing 
special methods. 
Botanical students have been fortunate in the 
existence of Strasburger’s well-known Botan- 
isches Practicum which, though primarily de- 
voted to general botanical morphology, also 
contains valuable directions for the practical 
study of plant-cytology. Students of zoology 
have had no lack of general works, such as 
those of Flemming, Carnoy, Bergh, Hertwig, 
Henneguy and Wilson, not to mention a num- 
ber of admirable works on histology ; but with 
the exception of Carnoy’s Biologie Cellulaire, 
published fifteen years ago and the-first of its 
kind, none of these works contain practical 
laboratory directions. Carnoy’s work is now 
too far out of date to be of much service to the 
modern student, and the same applies to Whit- 
man’s excellent Methods in Microscopical Anat- 
omy and Embryology published in 1885. A. 
Bolles Lee’s Microtomist’s Vade-mecum, especi- 
ally in the German edition, translated and re- 
vised by Paul Mayer, is indispensable to all 
students of microscopical anatomy, yet even 
this work does not supply the want which 
Hacker has now endeavored to meet. 
The ‘ Praxis und Lehre’ will, we feel sure, 
be of the highest service both to students and 
to teachers of cytology. As the name indicates, 
‘The Teaching Botanist. 
SCIENCE. 575 
it is not properly a laboratory manual, but hap- 
pily combines practice with descriptions of fact 
and the discussion of theory. The plan fol- 
lowed is to describe a series of ‘ objects,’ each 
accompanied by practical directions for the col- 
lection and preparation of material, a brief and 
clear account of the topic which it illustrates, 
and a review of the earlier history and more 
recent literature of the subject. The methods, 
like many of the descriptions, are in the main 
compiled from recent original works, and the 
author has wisely omitted all accounts of ele- 
mentary operations such as the use of the mi- 
croscope, methods of section-cutting and the 
like, which are adequately treated in Lee’s and 
other manuals. The student is thus brought 
directly to the real subject-matter and is en- 
abled to gain a connected idea of the facts, learn- 
ing at the same time how to procure and pre- 
pare the material for first-hand knowledge. 
Some of this material, it is true, is not readily 
procurable, some is practically out of the reach 
of all who are not specialists. Professor Hacker 
has none the less rendered a good service, es- 
pecially to teachers, by bringing together in 
readily available form the widely scattered ac- 
counts of material and method given by special 
investigators. The book isa model of clearness 
and brevity, and is well illustrated by figures 
drawn as far as possible from the latest sources. 
While we do not doubt that further experience 
will suggest many improvements on the practi- 
cal side, the book may be heartily recommended 
as a most useful adjunct both to lecture-courses 
and to practical work in cytology, and one that 
cannot fail to give a stimulus to the study. 
EK. B. W. 
By WILLIAM F. GaA- 
NONG, PHD., Professor of Botany in Smith 
College. New York, The Macmillan Com- 
pany. 1899. Pp. xii+ 270. Price, $1.10. 
The growth of interest in the teaching of 
botanical science has found expression in the 
publication during the past few years of a 
liberal number of books, concerned in one way 
or another with this teaching. Up to this time 
these works naturally fall into two categories— 
that of the text-book and of the laboratory 
manual—and although some attempt has been 
