4 THE ORIGIN OF THE NERVOUS SYSTEM 



wooden material, become possible when the materials 

 are steel or concrete. Protoplasm in consequence of its 

 physicochemical constitution represents a certain kind 

 of material in which certain kinds of pattern are possible, 

 and organismic pattern must lie within the range of 

 possibilities determined by this constitution. 



As regards the most minute and presumably the 

 simplest organisms, e.g., certain bacteria and ultra- 

 microscopic forms, if such exist, our knowledge is at 

 present insufficient to permit us even to say with cer- 

 tainty whether they are cells in the ordinary sense of 

 the word, and concerning their pattern as organisms 

 we are almost completely ignorant, but it is at least 

 certain that in the bacteria orderly differences between 

 surface and interior exist. The single cell is of course 

 primarily an organism, though it may as a part of a 

 multicellular organism become specialized and lose to a 

 greater or less degree its capacity for independent exist- 

 ence. And, finally, the multicellular form represents a 

 still more complex order and integration. 



ORGANISMIC PATTERN 



The fundamental fact for present purposes is that 

 the organism, as the term implies, represents an order 

 and unity of some sort. Concerning the character of 

 this order in the simplest living forms we know practi- 

 cally nothing, but as regards all other organisms we may 

 say that this order expresses itself in the appearance of 

 more or less definite spatial morphological and functional 

 relations and in a more or less definite and orderly 

 behavior of the whole. It is necessary before going 

 farther to inquire how the organismic pattern or order 



