THE ADVANCE OF BIOLOGY IN 1897. 
C. B. DAVENPORT. 
Tue delay in issuing the magnificent volume of L’ Année 
biologique for 1897 is regrettable; but the labor involved in 
bringing the work of the year into a condition where the result 
will be quickly accessible is clearly tremendous and the stand- 
ard of the editors seems to rise from year to year. As in the 
two previous years, I shall briefly sketch some of the results on 
which the editors lay most stress. 
Cytology. — Important advances were inde especially by 
Kossel and his pupils in the chemistry of the more active pro- 
teids of the cell, and particularly of the spermatozoón. The 
theory that the centrosome is the center of the cell move- 
ments in general received support from its relation to the tail 
of the spermatozoón and probably (as a series of microsomes) 
to the cilia of epithelia. The variations in the constitution of 
the spindle, out of continuous and discontinuous fibres, was 
made clear. The mechanics of mitosis were further illustrated 
by the behavior of artificial mixtures and of machines; further 
evidence for the dependence of membrane formation upon the 
presence of the nucleus was brought forward. - 
The Sexual Products and Fecundation.— The variability of 
the process of chromatin reduction was made clear by the 
demonstration of the absence of a longitudinal division of the 
chromosomes, in one instance, and of the absence of any sort 
of reduction in a second (Lee) ; the transformations of chroma- 
tin during the growth of the ovum were further studied; the 
idea that polar globules are only aborted eggs received support 
from Francotte's observation that in polyclads they may be 
fertilized and develop into gastrule. Ivanzov interpreted matu- 
ration as an extrusion of ferments that might otherwise destroy 
the spermatozoón. The conclusion that the centrosome occu- 
pies the middle-piece of the spermatozoón gained a general 
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