CELL-DIVISION. 35 
Fig. 13, I, J, shows several stages of the process just described in 
two asci of Lachnea scutellata. 
While this is taking place the nuclear beak becomes smaller and 
smaller until it is finally reduced to a mere thread in which chromatin 
and membrane are no longer recognizable. The centrosome remains 
for a short time as a deeply staining and sharply defined disk adhering 
to the plasma membrane. Very soon it becomes free from the mem- 
brane and is drawn back to the somewhat pointed nucleus, where it 
appears as a saddle-like thickening upon the point of the nucleus, or 
Fic, 13.—Free cell-formation in the ascus. 
G, H, Erysiphe is. I, J, Lachnea scutellata. 
G, the plasma membrane is complete; nuclear beak withdrawn and centrosome saddle-shaped, and 
_ Closely applied to the nuclear membrane. 
H, a mature spore with cell-wall; centrosome closely applied to nuclear membrane at upper side. 
I, J, portions of two asci showing several steps in process of free cell-formation 7x situ.—(After Harper.) 
as a simple disk (Fig. 13,G, H). The nucleus now gradually assumes 
its original spherical form, the chromatin passing into the structure of 
the resting stage, while the centrosome remains closely adhering to 
the nuclear membrane. 
It will be observed that in the specific case of cell-formation described 
the plasma membrane is completed before the nucleus has reached the 
resting stage, but in Lachnea (Harper, 1900) the daughter nuclei of 
the eight-nucleated stage are completely reconstructed before the beaks 
are formed. This may be, of course, a case of individual variation 
and of only secondary importance. 
