168 The Unity of the Organism 



rhythmic, or at least not of the same time-intervals as the 

 excitations, gradation in intensity of reaction, and so on. 

 To these he devotes more than a hundred pages, all under 

 the common heading, "Coordination in the Simple Reflex." 

 It is unnecessary to follow the matter further, sufficient 

 having been given to show something of the variety of ends, 

 all definitely and specifically contributory to the needs of 

 the organism as such, and all accomplished through differ- 

 entiation and integration of one relatively simple organic 

 structure, the reflex-arc. 



The Integration of Reflex-Arcs 



Our next task is to learn something of the combinations 

 among the myriads of reflex-arcs of which the higher nerv- 

 ous system is composed. The definition of the reflex-arc 

 given on a preceding page presents this mechanism in its 

 simplest terms, and so far as the definition indicates it would 

 seem possible for it actually to exist and be operative in 

 this simplicity. In fact, physiologists are accustomed to 

 assume such an entity and to call it the simple reflex-arc, 

 and its activity the simple reflex. But while such a concep- 

 tion is convenient and helpful for didactic purposes, espe- 

 cially as an aid to visualizing the earliest stage of cell inte- 

 gration in the evolution of the nervous system, as a matter 

 of fact, according to Sherrington, it probably never exists 

 in nature. "A simple reflex is probably a pure abstract 

 conception, because all parts of the nervous system are 

 connected together and no part of it is probably ever 

 capable of reaction without affecting and being affected by 

 various other parts, and it is a system certainly never abso- 

 lutely at rest." ^ 



The factual basis for the conception that one of the most 

 essential distinctions between the nervous system and other 

 systems of the body is the integratedness of the former, is 



