Wilson.] 47li [Feb. 20. 
tracoil back to \hv iiii(l(llo-])ioco as already rlcscrihod. It is an 
interestintjj fact that Avith tlie doulde stain the nrKMh'-)>iecc of the 
spenn is red wliile tlic nucleus is blue. 
The closing stages of karyokinesis present many interesting 
features. After their divergence, the daughter chromosomes are 
drawn out close to the arehoi»lasm-sj)here. This is followed by a 
remarkable phenomenon which has not yet been carefully 
described although a number of authors have given a partial 
account of it. Each chromosome, namel}'^, gives rise to a minute 
spherical vesicle, the chromatin being mainly aggregated round 
its periphery, Avhile the central portion is clear. At this period 
each daughter nucleus, therefore, is represented by a group of 
vesicles equal in number (probably 38) to the chromosomes. 
This is followed by the progressive fusion of the vesicles, their 
nixmber being rapidly reduced until only three or four remain. 
These finally unite to form the daughter nucleus proper, and this 
is followed or accompanied by the cleavage of the cytoplasm. 
When first formed the daughter nucleus is very small, irregular in 
shape, and stains very imperfectly. Dui'ing the resting stage it 
becomes evenly rounded, rapidly grows, and the chromatin 
gradually resumes its staining power. The staining ])ower of the 
chromatin reaches a maximum when in the form of chromosomes, 
a minimum in the daughter nuclei immediately after division. 
The formation of the " Zwischenkorper " is clearly shown 
during the anaphase. It arises from a group of microsomes 
staining intensely blue which are derived by the disintegration 
of the spindle fibres ; and it is an interesting and suggestive 
fact that the whole substance of the amphiaster, from the first 
formation of the sperm-aster onward, is found to consist of 
granules or microsomes clearly visible after treatment by various 
reagents (sublimate, sublimate- acetic, Flemming, etc.). 
During the reconstruction of the daughter nuclei the reticu- 
lated archoplasm-sphere becomes less distinct, and the daughter 
nucleus is pressed closely against it or perhaps even withdrawn 
into its interior. The remainder of the aster (astral rays) is 
converted into a large l^lue- granular mass, traversed by faint 
rays, which at first entirely suiTOunds the daughter nucleus. 
This mass subscMjuciitly breaks away and disappears on the 
