486 Harper . — Cell-Division in Sporangia and Asci. 
as a consequence a sharply angled polygonal outline in cross 
sections. The appearance of the sections at this stage is 
characteristically different from that in the last. The seg- 
ments seem to be delimited and separated from each other by 
rather broad granular plates, and if one had not observed the 
preceding stages it would be easy to believe that these figures 
indicated a stage in cleavage where the protoplasm was being 
cut up simultaneously by granular plates into uninucleated 
spores. The granular plates are very conspicuous in stained 
sections (Fig. 7), and careful observation shows that, in the 
case of every cell, cleavage is complete rather than in progress 
at this stage, the granular plates being really double, and 
composed of the closely appressed membranes of the swelling 
protospores. Still I am inclined to believe that the appear- 
ance of this stage in unsectioned and unstained material of 
Saprolegnia such as Biisgen studied was what led him to 
advance the doctrine of a fusion of the once separated spores, 
followed later by a second more definitive cleavage by granular 
cell-plates. As a result of this growth in volume the liquid 
in which the primary segments floated disappears. Whether 
it is taken up again as food by the spores from which it has 
been extruded or simply is forced out of the sporangium, or 
whether both of these processes take place, is not easy to 
determine. The spore-mass at this stage fills the sporangium. 
The protoplasm of the protospores is evenly vacuolar and not 
apparently more or less dense than in the cleavage stages. 
The next further step in development consists in a rapid 
multiplication of the nuclei by division. The divisions do not 
proceed as simultaneously as in the case of the earlier nuclear 
multiplication prior to cleavage, and we find spores containing 
1, 2 or 4 nuclei in the same section (Fig. 7). The apparent 
irregularity is due in part to the fact that the spore appears 
in several sections. The process of division continues how- 
ever till each segment contains from eight to twelve or possibly 
more nuclei. There is no evidence to be gained that the 
different spores finally contain exactly the same number of 
nuclei nor that each nucleus is removed by the same number 
