1 62 MAN, — THE ANIMAL 



reproductive reactions and upon which the Freud- 

 ians place so great a stress, we can only con- 

 jecture. Until it is more thoroughly analyzed, no 

 fundamental or permanent results will be obtained 

 by this school of psychologists. 



It is equally difficult to separate the stimuli as- 

 sociated with the "hunger urge." Muscular con- 

 tractions in the wall of the stomach seem to be the 

 immediate cause of hunger pangs, but what starts 

 these contractions? Thus far we are studying 

 simply the results and not the causes of such 

 changes. We know equally little about the other 

 "internal urges" which form a prominent part of 

 the modern study of the mind of man. Biology 

 has a long period of technical research ahead of it 

 before such questions can be satisfactorily an- 

 swered. 



There is another common phenomenon of the 

 senses that also awaits further study. This has 

 to do with that strange habit of closing the doors 

 of one sense or another in order not to hear the 

 passing street car or see the trees in the land- 

 scape. By diverting the mind, internal, visceral 

 sensations also pass unrecognized. Just what 

 happens awaits discovery in all such instances. 



The neuron, which is the basis for all forms of 

 nervous response, cannot act alone. It is im- 

 portant only when in contact with other neurons. 

 While it Is thus proper to describe the neuron as a 



