63 
its plasomes, just as the leaf or other multicellular organ grows 
by the volume increase of its cells. 
The question how these plasomes grow, after division takes 
place, is answered as follows: As the masses they compose pos- 
_ sess a large quantity of water, they are easily moved upon each 
other, therefore the process of intussusception is not necessary to 
cause their increase in volume. This increase, in case of a plasome ~ 
which has just divided, may be explained in a purely physical 
manner. By diffusion and absorption, water holding solid sub- 
stance in solution enters these little bodies and is assimilated ; 
in this way the solid matter of the product of assimilation fixes 
the volume of the plasome. 
The only question unanswered by this hypothesis is, “How 
does the dead substance, which posesses a certain molecular 
structure, become a part of the living unit in such a way that 
after a certain time it no longer posesses this structure but is an 
integral part of the living unit, and division again occurs ?” 
Just as the molecule is the final form element of lifeless matter, 
so is the plasome the final form element of living organism. All 
the processes of division occurring in the cell depend on this ability 
of the plasome to divide; for example, if a chlorophyll grain 
divide, it is not by the simple process of a part of the plasomes 
separating from the remaining portion, but by a sing lelayer of 
these units dividing. 
But the growth of the protoplasm must be distinguished — 
from that of the plasome; the latter, by growth, simply makes good 
its former volume, while the protoplasm grows by the increase in 
number of its plasomes. ; 
This theory of the manner of growth does not exclude the 
notion of increase in volume by the stretching caused by pressure. 
The foregoing, while nota literal translation, gives nearly the 
whole of this paper of Prof. Wiesner, which he says contains in 
brief the conclusions reached by several years of study, and while 
it may be regarded as an effort to consider the question of cell- 
growth from a new stand point, it is more especially an effort to 
make clear those points about which converge the new discoveries — 
about the life and development of the cell, and particularly the 
meaning of the processes of division. 
