192 BOTANICAL GAZETTE [MARCH 
this method of exchange is confined to this particular case, but 
since all of the essential constituents of protoplasm go into the 
nucleus of Peperomia sintenisii, it seems probable that the same 
thing happens in other organisms, and that this is rendered possible, 
as is probably the case in P. sintenisii, by the action of some substance 
or substances which continually pass out of the nucleus and cause 
a change in the cytoplasm. 
It may be that the previously mentioned change of the cytoplasm 
around the nucleus, just before division, is connected with the accumu- 
lation, outside the nucleus, of the substance which has passed from 
the nucleus; and that the disappearance of the nuclear membrane is 
connected with a change of the cytoplasm causing a suspension of the 
reaction between the cytoplasm and nucleoplasm. The disappearance 
of the membrane might then be by absorption, analogous to the 
absorption of the nuclear membrane between two fusing nuclei. 
The substances which made possible this absorption, by accumulating 
outside the nucleus, would probably not be the same as those which, 
by reacting with the cytoplasm, caused the formation of the nuclear 
membrane. On the other hand, it seems not improbable that during 
division the nuclear sap loses its power of reacting with the cytoplasm, 
for it may become mixed with the cytoplasm or form a definite part 
of the cytoplasm, as in the maturation of certain animal eggs. 
At the division of a cell of Peperomia sintenisii, as in other plants, 
the nuclear sap and nucleolus are lost in the cytoplasm; and so it 
is evident that nucleoplasm may also become a part of the cytoplasm. 
In many animals the clear substance which passes from the nucleus 
at maturation goes to form a special part of the embryo, and the 
passing of nucleoplasm to the cytoplasm has been considered as 4 
method by which the chromosomes influence the development and 
activities of an organism. The observations on Peperomia sintenisit 
seem to show that some substance or substances are being constantly 
passed from the nucleus to the cytoplasm, and this may also be a 
means by which the nucleus controls the activities of the cell. The 
control of the cytoplasm by the “resting” nucleus seems to be well 
illustrated in the formation of the blepharoplast of Derbesia (Davis 
: Here radiations pass from the nucleus out to the cell wall, 
and at the ends of these radiations granules which fuse to form the 
blepharoplast are laid down. 
