192 CELL INTELLIGENCE THE CAUSE OF EVOLUTION 



when these cells are stimulated in any way whatever, only 

 one kind of activity, some special activity, is the result. 



A discharging centre is for an action, it presides over it ; 

 when stimulated^ that action occurs more intensely, when 

 inhibited that action is restrained or suppressed. When 

 the centre is destroyed, the action is rendered impossible. 

 The doctrine of centres affirms that there is specialization 

 throughout the nervous system, that certain cells and 

 these alone are concerned with the performance of a par- 

 ticular function, that if that group be destroyed some par- 

 ticular activity becomes impossible. If this functional 

 specialization did not exist, then any one cell-group in the 

 central nervous system could act vicariously for another, 

 but this does not happen. The respiratory centre cannot 

 act for the sweating centre, nor either for the vomiting 

 centre. Just as a gland is not a muscle and cannot do 

 a muscle's work, so the centre for salivation is not that 

 for the flow of tears and cannot do its work. There is, in 

 fact, higher specialization in the nervous system than else- 

 where. One neural region governs the muscles of 

 breathing, another the diameter of arteries, another the 

 glands of perspiration, another those of gastric juice, an- 

 other the act of vomiting, while still others are the places 

 of the uprising of emotions, volitions, speech or memory. 



"The central nervous system is not a neural chaos in 

 which the units are unrelated or equivalent existences, 

 but it is a cosmos in which the functional units are differ- 

 ently endowed and are related to each other after the man- 

 ner of a hierarchy, the centres being arranged on several 

 functional planes. Centres are co-ordinated by being sub- 

 ordinated some to others. There is no equality of func- 

 tional position as there is no equality of capabilities. The 

 nervous system knows no such thing as socialism, if by 

 that is meant equality of position and powers. But in the 



