548 
David H. Dollev 
unity of mechaiiism which underlies function for all nerve cells throughout 
tlie ontogenetic and pliylogenetic scale wliatever tlie stiranlus as liereto- 
fore predicated from personal work and from tlie correlation of the resiüts 
of otliers. 
5. The nnity of the niicleiis-plasma coefficient among the different 
types of cells of the primitive animal as contrasted with its heterogeneity 
among different types in higher animals would appear to be a significant 
factor in differentiation of nerve cells. 
Regarding the Nissl snbstance as chroniidial apparatns: 
1. The functional hypertrophy manifest in plasma and nucleus has 
beeil connected with the specific piirpose of the forniation of chroniatiii 
in terms of Richard Hertvvig’s ideas regarding the reciprocal inter- 
action between these elements. The enlargement of the nucleus in its 
association with the morphology of the intra- and extra-niiclear chro- 
niatin gives independent evidence of a genetic relationship between theni. 
The Nissl snbstance, the cytoplasmic chroniatic constitiient, of niiclear 
origin in the sense that it is continiiously siipplied throiigh the contribu- 
tory mediation of the nucleus, is the piirposefiil prodiict of this intracellular 
coordination and the ininiediate som’ce of energy. To its formation both 
the plasma and the nucleus integrate as the single response to any form 
of Stimulation. For the nerve cell, this represents essentially its work 
on the side of the elaboration anu storing of energy and iip to the 
point of its transmutation into the nerve impulse. 
Regarding the cellular enlargement in general: 
1. The general significance of the enormoiis cellular enlargement 
is that of a functional overgrowth, a work hypertrophy. 
2. The contrast between this functional overgrowth and the normal 
inherent growth capacity independent of function, which the resting cell 
must largely represent, greatly broadens the liniits of the capacity of 
functional growth which can be ascribed to nerve cells. Even the cells 
so far universally foiind more or less hypertrophied from their functional 
localization Start at bh'tli from the common resting level with the same 
constant nucleus-plasma relation. With differentiation, the distinction 
must be made for nerve cells that this power of functional growth is 
greatly lessened. 
Regarding the natiire of differentiation in nerve cells: 
1. With a unity of mechaiiism, Chemical differences in the coni- 
position of chromatin as the specific snbstance most directly and essentially 
involved in supplying energy are necessarily predicated to explain certain 
