Harper . — Cell-Division in Sporangia and Asci. 523 
and Mosses has arisen in this latter fashion. For the Ascbmy- 
cetes it is impossible as yet to construct an ancestral line of 
development which shall settle this question. We can say 
however, as noted above, that the unlikeness in the method 
of spore-formation in the ascus and the sporangia which 
I have studied makes it impossible to assume any very direct 
relationship between the Phycomycetes and Ascomycetes. 
To keep clear this distinction in the method of cell-division 
in the sporangium and ascus I would propose that the term 
free cell-formation be restricted to the method of cell-division 
in the ascus. The method of division by which the sporangio- 
spores and conidia are formed may be described as cleavage by 
constriction. In Synchitrium decipiens and Pilobolus , where the 
division proceeds to the ultimate separation of the energides 
as protospores, the process can be called progressive and com- 
plete cleavage . In Sporodinia we have a restricted cleavage. 
In cutting off the gametes in Sporodinia and the conidia of 
the mildews we have division by simple constriction. The 
process is probably the same in the cell division of Cladophora. 
In cases such as the cutting off of the columella in Sporodinia 
and Pilobolus we have the process more or less modified by 
the appearance of internal cleavage by flattening and fusion 
of vacuoles. 
Doubtless further types and modifications of the cleavage 
process will be found in investigating other, even nearly 
related Fungi, and it is hardly necessary to attempt further 
applications to the general theories of cell-division until 
a larger number of cases have been worked out for comparison. 
