Harper. — Cell- Division in Sporangia and Asci. 503 
5. Formation of surface-furrows which deepen and meet 
the vacuoles, and thus cut the plasma into irregular and 
finally oblong sausage-shaped multinucleated bodies, which 
are further divided to form one or few nucleated energides, 
•the protospores. 
6. Nuclear division followed by cell-division, constituting 
embryonic development of protospores into mature binu- 
cleated spores. 
SPORODINIA. 
Sporodinia is a further type of the Zygomycetes, in which 
the asexual reproductive apparatus is considerably modified. 
The fungus occurs in nature as a parasite on various Hyme- 
nomycetes, especially Boleti , and, as described by Brefeld, is 
very easily grown on bread cultures. It is a very favourable 
object for the study of spore-formation in the sporangia. 
The whole development and ripening of the spores is here 
passed through in a very brief space of time, one hour from 
the first swelling of the end of the sporangiophore sufficing 
for the development of the ripened spores. The spores are 
thin-walled, variable in size, short-lived, and by no means so 
resistent to unfavourable environmental conditions as those 
of Mucor and Pilobolus. They retain their capacity for ger- 
mination only a week or two. Zygospores are produced 
much more abundantly by this fungus than by other members 
of the group, and serve the purpose of maintaining the 
existence of the fungus through a period of unfavourable 
conditions. 
The sporangiophores are here dichotomously branched, and 
with the ripening of the spores become regularly septate. 
The ends of the sporangiophore-branches swell to the form 
of flattened spheroids, whose transverse diameter is only about 
twice that of the extremely thick sporangiophores. The 
spore-plasma becomes aggregated in the form of a cap-shaped 
mass, thinning at its edges and lining the upper two-thirds 
of the spheroid. In sections the spore-plasma shows a regu- 
larly crescentic outline. The central and lower parts of the 
