S80 KANSAS UNIVERSITY QUARTERLY. 
of the trophoplasm by the spindle fibres from taking any part in 
the formation of the cell plate—these are considerations which 
seem to exclude the probability of a mutual interchange between 
kinoplasm and trophoplasm. 
Besides the dynamic role which the kinoplasm seems to play in 
the separation of the chromosomes of the dividing nucleus it, per- 
haps, exclusively enters into the formation of the cell plate and the 
plasma membrane which, in free cell formation, demarks the new 
cell from the general cytoplasm. A beautiful demonstration of 
this last process has been worked out by Prof. Harper.' He finds 
that in the ascus of Erysiphe the daughter nuclei of the last divis- 
ion which is to produce the ascospores remain attached to their 
centrospheres by means of a projection of the nuclear wall. The 
chromatin framework of the nucleus extends up into the neck pro- 
duced by the extension of the nuclear membrane and comes into 
intimate contact with the centrosphere. The radiations of the 
aster appear to be formed under the immediate influence of the 
nucleus and seem to grow outward from the centrosphere through 
the cytoplasm. Finally the kinoplasmic radiations of the aster 
bend backward toward the nucleus and increase in length. The 
radiations continue to grow, and at length they bend inward below 
the nucleus where they fuse together and form a complete mem- 
brane which demarks the nucleus together with a certain amount of 
cytoplasm, from the general cytoplasm of the ascus. When this 
process is complete the projection from the nucleus which was 
united with the centrosphere draws back and leaves the nucleus 
suspended in the cytoplasm. The plasma membrane of the spore 
is thus seen unmistakably to be formed by the kinoplasm. The 
fact that it remains in contact with the kinoplasmic radiations 
throughout this process is evidence that the nucleus has an import- 
ant function to fulfill, either in inciting the growth of the membrane 
and in directing the course which it shall take, or in contributing 
to the material for the growth of the new membrane. It has al- 
ready been observed that Strasburger conceives the union of the 
nucleus with the kinoplasm to be for the purpose of establishing 
direct communication between the nuclear substance and the grow- 
ing membrane. The fact that the chromatin of the nucleus also 
comes in direct contact with the centrosphere is an indication that 
the nucleus is also exerting a formative influence on the growing 
membrane. Harper points out that the processes just described 
are evidence that the kinoplasm is a specific part of the cell and 
1 Kerntheilung und freie Zellbildung im Ascus (Cytologische Studien. pp. 95-150). 
