CONFORMITY WITH PLAN 281 



concerning the structural principles of the nervous system 

 in animals. Every stimulus that reaches an animal affects it 

 in the same way — a wave of excitation arises in a nerve. All 

 waves of excitation are qualitatively alike, and do not permit 

 of our distinguishing between stimuli. 



On the other hand, all the nerve-fibres of the animal 

 are isolated. Each receptor nerve-fibre ends in a receptor 

 centre. The isolated nerve-fibre with its centre may be 

 described as an independent nerve-person. This arrangement 

 makes it possible to distinguish from one another as many 

 stimuli as there are nerve-persons. Now every muscle and 

 every gland is connected with a nerve-person. If we consider 

 this arrangement as a whole, we see that, on one hand, the 

 possibility is offered of summing up any chosen combination 

 of stimuli by cutting out certain receptor nerve-persons, 

 and, on the other hand, of making every sort of nervous 

 combination of the muscles and glandular structures, the 

 activity of which then gives a unified response. 



The binding together of the nerve-persons is effected by 

 net-shaped nervous connecting routes. The nerve-persons 

 themselves are merely representatives, and within the body 

 they transmit, on the one hand, the stimuH to which it is 

 subjected, and, on the other, those which it itself exerts. 



In the mark-organ are united the receptor representatives 

 in the combination characteristic for each animal, and in 

 the action-organ are similarly combined the effector repre- 

 sentatives. 



The combinations of representatives are so arranged, that 

 those of the main receptors are united into special groups, 

 and those of the main effectors into others. The groups of 

 nerve-persons may again have a representative of their own, 

 which we may call their captain ; and the captains may be 

 united into groups, represented by an adjutant. 



If we consider the whole body of representatives (of the 



