673 
shape can we derive the accurate relation of the volumes from the 
proportion between the lengths. To have a good chance in this 
respect | compared allied animal species, wherever obtainable, or 
at least those in which detinite homologous cells may be considered 
as similarin form. Besides spinal ganglion cells were particularly chosen 
for the calculations, on account of their regular, round shape, which 
as such leads more to conformity. It is self-evident, that cells were 
compared which differed as much as possible in size; thus individual 
deviations, which would affect regular relations, as are supposed to 
exist between the volumes of the nucleus, the plasm, and the cell, 
are minimized and recede into the background. The linear dimension 
of the plasm (equal to the cube root of its volume) was taken as 
the difference between the diameter of the cell and that of the nucleus. 
An exponent d can be calculated giving the relation between the 
volumes of the plasm YD and D, and the volumes of the cells C 
1 
C, 
first column of figures in Table Il are found. Most of these approach 
very closely 1.2 or 6/5. 
Old (6) P 0.27 d 
Besides it was found that el = Cv so that el ae 
Thus the value of the plasm-exponent 2 (= 0.27 d) can be calculated 
d D 
and C,, in the equation ( ) — D then the values recorded in the 
1 
Ja Neen JD} 
from the equation =) = — with the value of d calculated for 
lee D, 
every pair of cells investigated. The results of these calculations are 
given in the second column of figures of Table IL. Most of them 
differ but little from 1/3. 
Not being acquainted with the details of the data made use of 
in these calculations, we could not be certain beforehand, however 
guided in their choice by the principles stated, that they were indeed 
serviceable. In the case of Tragulus e.g. there seems to have been 
something wrong with them. But finding for a fair number of cell- 
couples, chosen on those principles, such a striking conformity in 
the results of the calculations, we feel justified in admitting the real 
existence of regular proportions. 
As was already stated couples of cells of similar form had to be 
chosen for the calculation to enable us to derive the volume from 
the diameter; but the general validity found earlier for the relation 
of volume between the ganglion cell and body, and considerations 
in connection with what follows, leave no room for doubt, that 
also between cells dissimilar in form, but functionally equal, the 
