506 Harper . — Cell- Division in Sporangia and Asci. 
it is plain that the ripe spores in the two types are not 
exactly homologous structures. Such variations in closely 
related forms are rather surprising, but in each case the 
abbreviated cleavage process is evidently an adaptation to 
meet the demand for a more rapid method of multiplication 
in the species in which it appears. Investigation will doubt- 
less lead to the discovery of still further modifications of the 
process. It may be noted that the absence of winter spores 
in Synchitrium decipiens , as compared with S'. Taraxaci where 
they are present, may be correlated with the longer process 
of cleavage and embryonic development in S. decipiens. It 
is hardly worth while to propose changes in nomenclature 
to distinguish the different forms of spores already described 
until a larger number of forms have been thoroughly studied. 
It is plain, however, that the term sporangiospore, as used 
by Leger, includes several structures quite distinct as to the 
method of their formation. The use of the term protospore for 
the ultimate product of cleavage in such forms as Synchitrium 
decipiens , Pilobolus and probably Saprolegnia , is certainly con- 
ducive to clearness. The ripened product of the sporangium, 
whether the cleavage process is more or less complete, and 
whether embryonic development is present or absent, may 
still be loosely designated as a spore or sporangiospore. 
Cell-division also occurs in Sporodinia in the cutting off 
of the gamete-cells from the suspensors in sexual reproduction. 
This is an interesting case, since the mass of protoplasm to be 
cut in two is nearly as great in diameter as in the sporangium 
when the columella-wall is formed. There, as we have seen, 
the cleavage is accomplished by a row of vacuoles that flatten 
and fuse edge to edge. Here in the gamete-formation, how- 
ever, the cleavage is accomplished entirely by a circular 
furrow proceeding from the surface to the centre, as in the 
cutting off of the bulb in Pilobolus. The nuclei are extremely 
numerous and are distributed in the protoplasm without any 
apparent relation to the plane of cleavage. The ingrowth 
is simply a deep narrow furrow and not the growth inward 
of a ring of fungus-cellulose. The cellulose-wall is formed 
