GURRENT-LITERATURE, 
BOOK REVIEWS. 
A cytological review. 
CYTOLOGICAL literature has been accumulating so rapidly during the past 
few years that investigators have keenly felt the need of a critical review of 
the more important papers. It is extremely fortunate that Strasburger, the 
man best fitted to make such a review, has undertaken the work and pre- 
sented the results in his masterly way, which makes the book a necessity to 
everyone engaged in cytological research. The volume’ contains a brief, 
judicious summary of the cytological work which had appeared up to August 
1899. It is more than a summary, for the author has taken this opportunity 
to present his own most recent researches upon these subjects, and has given 
the conclusions which he has reached from a fresh study of the literature and 
from his own work 
The reduction division.—In introducing this subject the statement is made 
that the existence or non-existence of a reduction division has not yet been 
settled, either in plants or in animals. After presenting the evidence, both 
for and against a reducing division, he concludes that in both the nuclear 
divisions concerned in the formation of spores from spore-mother cells, the 
splitting of the chromosomes is longitudinal, and consequently there is no 
reducing division. The peculiarity of the first division which follows the 
numerical reduction of the chromosomes lies in the fact that the chromo- 
somes incline to an early separation and very soon undergo a second longitu- 
dinal fission. The second nuclear division which follows the numerical 
reduction of the chromosomes merely distributes the chromosomes, which are 
already marked out when the frst division occurs. In the bryophytes and 
most of the pteridophytes the numerical reduction of the chromosomes occurs 
long before the process of fertilization; but in the heterosporous pterido- 
phytes the two processes are much less widely separated, and in the flowering 
plants reduction of the chromosomes and the process of fertilization come 
very close together. This nearing of the reduction of chromosomes to the 
process of fertilization is plainly a derived condition caused by the reduction 
of the gametophyte. The author still regards the reduction of chromosomes 
as a phylogenetic phenomenon, which is not the cause but rather the result of 
STRASBURGER, EpUARD: Ueber Reduktionstheilung, Spindelbildung, Centro- 
Somen, und Cilienbildner im Pflanzenreich. 8vo. pp. xx-+224. #4 
Gustay Fischer. 1900. Af 10.50. 
AoerI 145 
