No. 374.] REVIEWS OF RECENT LITERATURE. Lag 
form, there is a continuous series of developmental changes, each 
stage being based upon the preceding one and conditioned by it. 
The growth of the primary oécyte and the formation of the yolk 
were considered at some length. A true “ yolk nucleus ” arises, as 
the author believes, from the nucleus, and this by continued growth, 
and later by fragmentation, gives rise to very small spherules, which 
later, by enlarging, form the yolk spherules. The yolk nucleus is an 
albuminous body closely allied to, if not identical with, the yolk or 
deutoplasm. This was indicated bya large number of microchemical 
tests. The yolk nucleus at a very early stage of the egg was also 
shown to be the only albuminous body in the cell ; for the rest of 
the extra-nuclear part of the cell is almost exclusively composed of 
pseudo-nucleinic substances. Evidence was cited which indicated 
that the yolk nucleus was formed by the nucleus, and that it enlarged 
by constant additions to it from the nucleus. 
e more important results of a study of the maturation and 
fertilization processes might be briefly stated, although a fuller 
account will appear in the published paper. ‘The first maturation 
spindle arises entirely from the germinal vesicle. It is peculiar in 
that it is barrel shaped, and does not, as far as can be determined, 
bear at either end centrosomes or asters. The first polar body 
receives sixteen chromosomes, while sixteen remain in the egg. The 
second maturation spindle is also barrel shaped, and is also devoid 
of centrosomes and asters. Eight chromosomes remain in the egg. 
The sperm entrance was described in detail, and evidence was 
brought forward to show that the centrosomes - the first cleavage 
figure were derived from the sperm. 
The spindle of the first cleavage figure appears to be formed from 
the segmentation nucleus, there being no ‘central spindle’ extending 
between the centrosomes. The spindle itself was shown to be 
barrel shaped, the daughter chromosomes reforming into a vesicular 
nucleus at the ends or heads of the barrel. A “ Zwischen-Korper ” 
also arises, as in the maturation stages, by a concentration of the 
spindle fibers at the equator of the figure. After the reformation of 
the daughter nuclei, and after division of the cell body, the paired 
daughter centrosomes and asters diverge. The daughter nucleus 
later moves up between the asters, and prepares for the next division. 
Comparative independence and parallelism of the processes under- 
gone by the centrosomes and asters, on the one hand, and those of 
the nuclei, on the other, become very strongly probable. Detailed 
evidence in support of the above points will be given in the published 
paper, a preliminary notice. ) 
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