MENTAL AND SOCIAL EVOLUTION 109 



by the patterns of nerves in the brain, and this pro- 

 duces generalizations and abstractions. It, also, in its 

 normal condition, produces effective co-operation in all 

 the movements of the muscles. When there is a lack of 

 proper co-ordination for any cause, such as lesion of 

 the brain, there results that condition we call abnormal 

 mentality, in its different forms, or insanity. This co- 

 ordination is prevented, also, by intoxication, or by any 

 pathological effect on the tissue. The whole is physi- 

 ological in process, while the result is impressions, 

 coming from the environment, by way of the senses, 

 into the nervous structure, and then further producing 

 a resulting molecular motion, which is the psychical 

 phenomena. It is all the result of natural force, the 

 "persistence of force" acting along the line of least re- 

 sistence. 



The structural neural centers furnish fixed nodi, in 

 which functions operate in a very variable and unstable 

 way. The processes, while of course determined by 

 what are termed material structures, are so modified 

 physiologically, by the association fibres of con- 

 duction, crossing and mediating the sensory, and motor 

 centers, permeating every part of the brain structure, 

 that they must not be considered localized in the sense 

 of the old phrenology. It is probable that the higher 

 in the brain is the locality of neural function, the more 

 universal are the contributions, by all parts of the 

 conduction paths, beginning at the periphery of the 

 body, running through the ganglia, the myel, the 

 oblongata, mesencephalon, diencephalon, the cerebrum, 

 and ending in the various association centers of the 

 prosencephalon. Psychological abstraction, and gener- 

 alization evidently occur in these higher parts, and 

 they are the effects of the most complex functions, of 



