484 Harper . — Cell-Division in Sporangia and Asci . 
on the contraction of the protoplasm becomes much more 
marked, the furrows open widely and the masses of proto- 
plasm tend to round themselves up. 
The cleavage-segments produced in this way are seen to be , 
unequal and as a rule multinucleate. The cleavage-furrows 
have so far shown no tendency to orient themselves with 
reference to the nuclei. But as the process advances, and the 
protoplasm is cut into smaller and smaller masses, we find the 
nuclei more evenly distributed, and it is seen that none of 
these portions are left without nuclei. In the end the result 
is always the separation of the protoplasm into uninucleate 
masses (Fig. 6). The process which at first seemed to be in- 
dependent of the nuclei is seen finally to be directed solely 
from the standpoint of their distribution. The cleavage, as 
has been already noted, is attended by a very pronounced 
shrinkage of the protoplasm. This began while the segments 
were still multinucleate, and by the time cleavage is complete 
the segments are so reduced as probably not to occupy more 
than one-third of the volume of the primordial cell. An 
exact estimate of this reduction is very difficult. Rothert 1 
estimates the shrinkage of a Saprolegnia sporangium at 
a corresponding stage at thirteen per cent. It is to be noted 
that the cell does not entirely fill the membrane at these 
stages, sections always showing a considerable open space on 
one side or the other (Figs. 4, 5). This indicates that loss of 
water and volume begins prior to cleavage. To be sure, this 
reduction prior to cleavage may be artificial and due to fixation, 
though the structure and appearance of the protoplasm give 
no evidence of this. The cavity around the protoplasmic 
mass prior to cleavage must be filled with water or at least by 
solutions which are not precipitated in fixation nor stained by 
ordinary reagents, but at the end of cleavage the uninucleated 
segments are floating or, better, imbedded in a liquid which 
contains an abundance of dense oily droplets, which blacken 
with osmic acid and take up stains (especially orange G.) 
with considerable avidity. There is generally a layer of 
1 l. c., p. 315- 
