34 S. BENT RUSSELL 



A 2, A simultaneous mix in several nerves results similarly 

 in a certain movement or movements. 



B, The effect of time intervals between discharges in deter- 

 mining variation of response is the same in the apparatus as 

 it is in a nervous system. 



Of course there are types of response to environment that are 

 not covered by this discussion. It is believed, however, that 

 the theory advanced herein with some modifications will be 

 found to answer for a large part of the field which is not 

 included. 



In reviewing the different arrangements shown in our tables 

 and diagrams one fact seems to be brought into prominence. 

 It is that the channel that is to be made to govern after suit- 

 able experience must be there in the first place as part of the 

 structure. In regard to nervous systems this is not such a 

 great difficulty as it may seem. Remember the shocking stupid- 

 ity often shown by animals usually thought intelligent and the 

 limited field in which animals can be trained. On the other 

 hand there is reason to think that in life many nervous chan- 

 nels remain undeveloped. Moreover there is abundant evidence 

 in animal behavior to show that the associative memory of 

 each species is in proportion to the complexity of its nervous 

 system.' 



Our mechanical system may be thought at fault because it 

 requires signals to succeed each other in order to affect the 

 opening of the transmitters, so that if two sensations were 

 simultaneous they would never become associated together. 



The answer is that each of two simultaneous signals may be 

 associated with a common signal which precedes them. 



To summarize briefly the points covered we have shown that 

 a comparatively weak nervous channel may become a com- 

 paratively strong one if it be provided with two sensory points 

 and with outside occurrences that shall cause the two points to 

 be excited in succession from time to time. We have shown how 

 this principle will account for the different ways of learning 

 and habit forming. 



We have also demonstrated a mechanism that will simulate 

 in its various forms the working of nervous discharges. With 



7 Loeb, J. Comparative Physiology of the Brain and Comparative Psychology. 

 New York and London, 1900, p. 13. 



