SIZE CHANGES IN NERVE CELL BODIES 323 
and all complications of comparison sufficiently discounted. 
For species relativity of plasma to nucleus, a constancy can not 
be denied until it is analyzed apart from immediate function. 
This applies not only to the nerve cell, but to all specialized cells 
in their proper measure. Until that be done, criticisms of Rich- 
ard Hertwig’s nucleus-plasma relation, of which the species con- 
stancy is an extension for the nerve cell, are not worth the paper 
on which they are written. When it is done, there is still no 
reason to this investigator to doubt that the nucleus-plasma 
relation will be a fact and no longer a theory. 
CONCLUSIONS 
The planimeter or area method applied to the stages of func- 
tion affords results which are identical with those from the dia- 
metral method of measurement, both in size and in nucleus- 
plasma relations. Previous conclusions for functional size 
changes and species size relations of nerve cell bodies are verified. 
The value of the planimeter method is as a mutual check on 
the diametral method, particularly in irregular cells. Alone it 
has no special or superior value, while it gives only two dimen- 
sions, with smaller variations than in volume calculation, and is 
quantitatively misleading. 
Collective averages of cells irrespective of their functional 
state, which has been the usual basis of comparison between in- 
dividuals, afford inconstant results and should be discarded. 
It is a scientific solecism that function, the one faculty which 
results from the differentiated state, is the one factor which has 
been neglected in the measurement of differentiated cells. To 
deny functional size changes on this basis because of small and 
inconstant variations between one animal and another, as Kocher 
has done, is a fallacy, and such results indicate only the tend- 
ency to a uniformity of absolute species size for corresponding 
nerve cell bodies. 
