493 
in the Hymenomycetes. 
daughter-nucleus a new nucleolus is formed, and very soon 
a further division of the two nuclei takes place, which appears 
to be much the same as that just described. Rosen does 
not give any details as to the precise way in which the final 
separation of the nucleus into two daughter-nuclei is accom- 
plished, whether by constriction of the primary nuclear mem- 
brane, or by its disappearance and the subsequent formation 
of two new ones, points of sufficient importance, one would 
have thought, to have been carefully determined. 
Gjurasin has recently published a paper upon nuclear 
division in the asci of Peziza vesiculosa x , which has an 
important bearing on some of the facts mentioned in this 
paper. The nucleus of the young ascus consists of a nuclear 
membrane, chromatin-network, and a large nucleolus. By 
means of Hermann’s safranin-gentian violet, he has been able 
to colour the network pale blue-violet and the nucleolus ruby 
red. In the process of division, the nucleus elongates slightly 
in the direction of the long axis of the ascus ; the nuclear 
network becomes granular, and now colours red. A spindle- 
figure is then formed, the threads stretching from the proto- 
plasm at both ends of the now barrel-shaped nucleus, to the 
middle of the latter. At each pole of the spindle, protoplasmic 
radiations can be made out, but no attraction-spheres. The 
granules of the nuclear network pass to the equator of the 
spindle, divide here into two halves, and move very quickly, 
to the two poles of the spindle. The nucleus elongates still 
more, and the radiating striae gradually disappear. The 
nucleolus has remained unchanged all this time, but now 
becomes slightly elongated. The nuclear membrane finally 
disappears and the nucleolus comes to lie directly in the 
protoplasm. The two daughter-nuclei become surrounded 
with new nuclear membranes, and the nuclear network again 
colours blue- violet. Nucleoli make their appearance in the 
daughter-nuclei, as very small bodies whose size continually 
increases. As the nucleoli of the daughter-nuclei increase in 
1 Ueber die Kemtheilung in den Schlauchen von Peziza vesiculosa , Bulliard, 
Berichte der Deutsch. Bot. Gesellschaft, Bd. XI. p. 113, 1893. 
