i8 THE ORIGIN OF THE NERVOUS SYSTEM 



organismic pattern. The conclusion that organismic 

 pattern arises in the final analysis through the relation 

 between protoplasm and environment does not of course 

 exclude the possibility that such pattern once estab- 

 lished may persist through processes of reproduction, 

 i.e., may be inherited. 



Before accepting this conclusion, however, it is 

 necessary to examine briefly certain aspects of the 

 problem of pattern which have not yet been considered. 

 Except perhaps in the simplest organisms, protoplasm 

 exists in the form of cells with differentiation into 

 nucleus and cytoplasm, the nucleus being commonly 

 regarded as the fundamental portion of the cell. The 

 cell itself represents an organismic pattern and is 

 primarily an organism, though it may undergo integra- 

 tion with other cells into the pattern of the multicellular 

 organism. While there is every reason to believe that 

 the factors concerned in the origin of cell pattern are 

 essentially the same as those concerned in the origin 

 of other organismic patterns, we may for the moment 

 accept cell pattern as given and inquire whether the 

 pattern of multicellular organisms is inherent in the 

 cells. The investigations of recent years in the fields 

 of genetics and cytology have led to the postulation of 

 definite chromosome patterns differing for different 

 chromosomes, and many biologists believe that the 

 totality of chromosome patterns in the nucleus of the 

 germ cells of a species represents in some way, and con- 

 stitutes the basis of, the organismic pattern which 

 appears in the development of the individual. 



Cytological investigation, however, has established 

 beyond question the fact that every cell of the indi- 



