22 THE ORIGIN OF THE NERVOUS SYSTEM 
organismic when it exists. Moreover, it is not primarily 
the material exchange between protoplasm and environ- 
ment, but the ordering and controlling of this .Change in 
definite ways which constitute the fundamental charac- 
teristic of organismic pattern. In short, however it 
may arise, organismic pattern is not simply the pattern 
of the material exchange between protoplasm and 
environment but rather a definite behavior pattern of 
different regions, cells, or cell groups. The fundamental 
factor in determining protoplasmic behavior of organis- 
mic character is the nonspecific, quantitative factor of 
excitation, and with excitation transmission is associated. 
In view of all the facts, then, the logical procedure in 
attacking the problem of the origin of organismic pattern 
is to determine whether, or to what extent, excitation 
and transmission are actually concerned in determining 
this pattern. And since the data of both ontogeny and 
phylogeny indicate that organismic pattern once estab- 
lished undergoes progressive complication, it is evident 
that we must first of all attempt to discover the simplest 
terms in which organismic pattern appears in nature. 
The following chapter is devoted to a consideration of 
this question. 
