1912] CURRENT LITERATURE 443 
The tenth and last chapter deals with heredity and sex. The hypothesis 
offered by the author several years ago that the female regularly possesses a 
chromatic element, or something else in addition to the possessions of the male, 
is made the key to the entire discussion of this subject, and a series of facts is 
presented which give the hypothesis considerable apparent plausibility, 
although the philosophical basis for it seems to the reviewer to be a little 
strained. This basis is found in the statement that the female as compared 
with the male has an additional function, namely the supplying of nourishment 
to the young zygote. On the other hand, it may be pointed out that the male 
differs from the female in many functions, and is in many respects morpho- 
se differences as additions to the female. If the egg has the added function 
of nourishing the young zygote, the sperm has the added function of motility, 
and there seems no better a priori ground for expecting an additional chromatin 
element to represent one of these additions than the other. The reviewer 
believes that there is no sufficient ground at present for the assumption that 
sex is always determined in the same manner. It cannot be determined as yet 
whether the basic differences between the sexes are quantitative or qualitative, 
and in either case the same results might be attained by any one of several 
different methods. The attempt to bring the sex-phenomena of all organisms 
under a single viewpoint is premature. 
Each of the chapters is followed by a “bibliography,” but the meagerness 
of the literature lists may be judged from the fact that they include only 
46 titles from 26 authors, including 14 of CASTLE’s own papers. This may 
to show the limitations of its author’s aims. Extensive literature lists are 
indispensable to students, but would defeat their own purpose in a book 
intended primarily for popular reading. 
* The press work is excellent and typographical errors are few, though 
“reversion” is rendered “revision”? in the heading of chap. iv.—GrorcE H. 
HULL 
NOTES FOR STUDENTS 
e mycoplasma theory.—In spite of many attempts to establish the 
Eriksson? in a brief article occasioned by MARESCHKOWSKI’S} appropriation 
? Eriksson, J., Uber die Pere ERE a ihre Geschichte und ihren Tages- 
stand. Biol. Centralbl. 30:618-623. 19 
3 MarescukowskI, C., Theorie der zwei Plasmaarten als Grundlage der Sym- 
biogenesis. Biol. Centralbl. 30:278 gio, 
