84 KANSAS UNIVERSITY QUARTERLY. 
size of the developing membrane, and the nucleus as the bearer of 
the inheritable qualities must govern these characters. In the 
latter case, the direction of the cell plate having once been estab- 
lished, the problem is a comparatively simple one. Whether or 
not a kinoplasmic connection of the nucleus with the forming 
plasma membrane is necessary might depend in the individual 
cases upon the energy of the nuclear influence, the distance of. the 
daughter nuclei from the growing membrane, and the sensitiveness 
of the cytoplasm in transmitting the nuclear influence. These are 
moments to which Haberlandt has called attention in considering 
the necessity of the proximity of the nucleus to those regions where 
growth is taking place most rapidly or is continuing the longest, ! 
and their application in this instance is equally evident. 
It seems fairly certain from the forgoing observations that the 
bulk of the nucleolar substance of the pollen mother cell remains 
in a state of solution after the daughter nuclei have gone into the 
resting state and is used, in part at least, in the formation of the 
cell plate. The proposition seems to me to be a reasonable and 
well-grounded one that the nine-tenths of the substance of the nuc- 
leolus of the mother cell which has not been used in the formation 
of the nucleoli of the daughter cells has been devoted to the build- 
ing up of the new structuaes which arise during cell division. It 
may be that the kinoplasmic fibres sever their connection with the 
daughter nuclei so early in the formation of the cell plate because 
the nucleolar substance is to be obtained outside of the daughter 
nuclei. 
If it is a fact that the nucleolus is merely reserve material which 
is destined to take part in the formation of the new structures of 
the dividing cell, then it must be regarded as reserve material of a 
very special potentiality. The long waiting of the mother cells 
and the gradual accumulation of nucleolar material already referred 
to are apparently a preparation for the critical time when the divis- 
ions of the mother cells shall follow each other in quick succession. 
At such a time the energies of the mother cell are probably taxed 
to their utmost so that the ordinary activities of the cell are in 
abeyance. The nucleolar substance is probably one of those which 
needs the influence of the nucleus for its formation, and at the time 
of nuclear division this influence could possibly not be given. 
This would then necessitate the previous preparation of the nuc- 
leolar substance as we have observed to be the case with the pollen 
mother cells of Asclepias. 
fees pseL02; 
