Harper. — Cell-Division in Sporangia and Asci. 505 
the two protoplasmic masses very soon brings the two 
membranes together and the contents of the sporangium 
are thus cut off from the sporangiophore by the new plasma- 
membranes. Between these a cell-wall is soon laid down. 
Cleavage of the spore-plasma begins at once by surface- 
furrows and clefts, which are rather wide and without the 
aid of vacuoles cut from below upward (Fig. 36) and, later, 
from both the upper and lower surface of the sporangium, 
thus dividing its contents into irregular polygonal blocks. 
There are two or three layers of these blocks in the apical 
thicker portion of a well-developed sporangium. At the 
edges of the spore-mass it is cut into only a single row of 
blocks (Fig. 37). These masses are very variable in size, and 
each contains a large but variable number of nuclei. They 
correspond morphologically to the blocks into which the 
spore-plasma of Pilobolus is first divided by the surface- 
furrows and vacuoles. They generally, however, contain 
many more nuclei than do the latter. With this the process of 
cleavage is complete in Sporodinia. A thin wall is built about 
each of the cleavage-masses which becomes at once a spore. 
The sporangial-wall is never thickened as in Mucor and 
Pilobolus , and bursts immediately for the escape of the spores. 
I have not detected by stains any intersporal substance, 
though the spores tend to adhere slightly when the spor- 
angium is broken on a microscope slide. In nutrient liquids 
the spores round themselves up and put out a germ-tube 
very soon without any noticeable swelling. They contain 
from ten to fifty or so nuclei. 
Sporodinia shows thus a very interesting abbreviation of 
the process of spore-formation as compared with Pilobolus 
or Synchitrium decipiens. It is seen, however, that the 
process in Sporodinia is related to that in P. crystallinus 
very much as the cleavage in Synchitrium decipiens is 
related to that in S. Taraxaci , except that in the latter 
the spore germinates as a sporangium. In Sporodinia 
and in Synchitrium Taraxaci the process stops with what is 
the initial stage of the process in the other two forms, and 
