100) CELL AND NUCLEAR DIVISION IN FULIGO VARIANS 249 
so as to form tissues,z. ¢., aggregates of cells with specific shapes 
and dimensions, only became possible after cell division came to 
bea function of the same mechanism which effects the division 
of the nucleus, but, as Strasburger (22) long ago pointed out, 
the process itself is by no means necessarily dependent upon the 
existence of this particular mechanism or of any correlation 
whatever with nuclear division. 
Hofmeister (8) calls attention to the fact that the division 
of protoplasmic masses for the formation of reproductive cells is 
quite universally accompanied by loss of water and reduction of 
volume with increased density of the protoplasm. This phe- 
tomenon of contraction and loss of water is especially conspicu- 
ous in the process of spore formation in sporanges, as I have 
already noted. It seems a fairly natural assumption that the 
tensions set up in a mass of protoplasm which is contracting as 
@result of loss of water may be utilized in some fashion to pro- 
duce the extremely irregular cleavage furrows which we observe 
in the early stages of spore formation. That these furrows, 
however, are not purely mechanical in their origin and analogous 
‘0 the fissures that appear on the surface of a drying colloidal 
Mass js shown, as I have noted elsewhere, by the fact that, 
_ oe they never cut off Sr inne containing no 
lacks 5 ultimately they produce approximately equal uni- 
a... Some form of organization must be assumed 
the cleava 2 in the protoplasm which determines the progress of 
~~ ge So as to lead to a constant result. Still, even with 
fe “sumption, the possibility remains that the source of the 
Seg eae controlled may be in the tensions produced 
Nn due to loss of water. 
Usiversiry op Wisconsin, 
INDEX OF LITERATURE. 
Mortierella Van Tieghemi. Beitr. zur Physiol. der 
: /’. Dr Bary. A i, wiss, Bot. 3 > 279. | 
der Pil, oy Vergleichende Morphologie, Physiologie und Biologie 
€, Bacteria und Mycetozoa. London. 
: * Bacuwany, H- 
Pilze, Jahrb, 
