128 
R. A. HARPER 
Conard (6) finds the process of spore formation in Lycogala exiguum 
entirely similar to that I have described for Fuligo (14). Rytz (28) 
finds that in Synchytrium succisae nuclear division continues during 
cleavage as I have described for Synchytrium decipiens and for Fuligo 
varians and describes the cleavage process as essentially similar to 
that in S. decipiens. Rytz's figures establish the existence of surface 
furrowing beyond question for this form. 
Bally (2) is inclined to accept the conception of cleavage by 
surface furrows rather than by cell plate formation for Synchytrium 
taraxaci, though stating that his material did not show the stages 
necessary finally to settle the question. Tobler (33) believes that 
cleavage takes place by surface furrows in S. pilificum and S. pyrifof we. 
A number of other recent authors, supposedly using modern methods 
of technique, still report cases of so-called simultaneous cell division of 
multinucleated cell bodies. Baum (5) claims that in Chlamydomucor 
and Coprinus and a number of other forms simultaneous formation of 
a cell plate across the entire hypha may occur, while admitting that 
in hyphae with a central vacuole the cell plate is regularly formed as a 
peripheral ring which progressively widens inward. He admits further 
that this same progressive formation of a cell wall may occur in hyphae 
which are filled with dense cytoplasm through their entire cross 
section. Baum holds that the essential feature in the process in both 
cases is the accumulation of granular material to form a cell plate, 
which is then transformed into a wall and in this he follows the older 
views of Strasburger. These granules he identifies with the so-called 
cellulin granules of Pringsheim. Baum's evidence for the existence 
of simultaneous formation of a cell plate across the entire diameter of a 
hypha is quite inadequate. His figure i, Tafel III, probably repre- 
sents a stage after the cell division is complete. 
Davis (7) describes the formation of zoospores in Saprolegnia 
mixta as a process of cleavage from the central vacuole outward and 
accepts the account of earlier authors as to the loss of turgor of the 
sporange when cleavage is complete and as to the subsequent apparent 
fusion of the newly delimited spores. His figures 33 and 34 are, how- 
ever, quite unlike any cleavage process described elsewhere and he 
asserts that the final step in the separation of the spores consists in the 
breaking down of fine strands of cytoplasm by which the spores have 
been connected. For Derbesia, Davis (8) describes and figures the 
cleavage in the sporange as taking place by branching furrows from 
the periphery inward. 
