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R. A. HARPER 
droplets resembling vacuoles are especially favorable for the demon- 
stration of the parallelism between the exudation of water and the 
formation of the cleavage furrows. I have pointed out the evidence 
for a similar parallelism in the case of Synchytrium decipiens, where 
the extruded liquid contains substances which are blackened by osmic 
acid. Kusano (19) has observed the same extrusion of liquid in S. 
puerariae though denying that it is of universal occurrence in this 
species. The formation of vacuoles from which cleavage furrows 
may arise in Pilobolus and Phycomyces is undoubtedly a similar 
phenomenon bearing the same general relation to the cleavage process. 
Such loss of water from sporanges has long been associated with the 
ripening processes by which the watery protoplasm of the hyphae or 
Plasmodium is transformed into the condensed and dust-like mass of 
spores. I have already pointed out the possibility that this exudation 
of water may at least be a factor in the process of cleavage on the 
assumption of an analogy between the furrowing of the spore-plasm 
and the cracking of a drying colloidal mass. 
In a recent paper with Dodge (15) we have also pointed out the rela- 
tion of this same extrusion of water into vacuoles in the early stages of 
the formation of the sporanges of Trichia to the formation of the capil- 
litium. An essential and doubtless primitive feature of the transition 
from the expanded vegetative condition to that of the dust-like spores 
for reproduction in these slime moulds is the exudation of water and 
it is quite to be expected that from the physical chemical standpoint 
the formation of the capillitium, the production of thick spore walls 
and condensed reserve products, and even the process of cell division 
itself would all develop in a manner most intimately related with and 
dependent on the fundamental process of getting rid of superfluous 
moisture. Still as I have elsewhere emphasized cell division in these 
sporanges cannot be regarded as simply a matter of the drying out 
and cracking to pieces of a colloidal mass. The extrusion of water 
into internal vacuoles shows that the process is initiated and con- 
trolled by changes in the spore-plasm itself. The fact that the final 
furrows always separate uninucleated spores is also proof of organi- 
zation in the segmenting mass. 
Visible evidence of this organization such as we find in connection 
with the processes of cell division in many plant cells is entirely 
lacking in these sporanges. There seems to be no evidence whatever 
for the existence of such systems of specially oriented fibrils as are 
