730 Dynamic Theory. 



thrombosis whereby certain of the blood tubules are stopped up by a 

 clot and the parts of the brain beyond the obstruction thus deprived of 

 their blood supply ; special stimulation by intoxicants, poisons and 

 other agencies ; mechanical injuries, extreme cold, old age, &c. The 

 quality of the blood often becomes impaired through general disease. 

 And it may be supposed that the quality and efficiency of the cells and 

 other nervous tissues themselves, likewise deteriorate through disease, 

 alcoholism, &c. Derangement of the digestive and sexual functions 

 reacts often upon the brain, producing hysteria, mental depression, and 

 in some cases irritability and changeableness of temper and disposition 

 to deceit. ' ' In some cases recorded by M. Lallemand the most extreme 

 mental depression was engendered by the presence of ascarides in the 

 rectum." ( Carpenter.) 



The forms which insanity takes are extremely varied. It may be that 

 the derangement is confined to intellectual processes, the emotions not 

 being specially involved. In such cases the recollection or some special 

 division of it fails first, so that some important element that should enter 

 into the composition of ideas and volitions is wanting, leaving such 

 ideas and volitions incomplete and faulty. As one after another of the 

 memories fails, the connections and associations between ideas are de- 

 stroyed, so that the cerebral movement is reduced to incoherent and 

 unrelated ideas, which when expressed convey no sense. The will com- 

 posed of the incongruous stimuli of these disconnected ideas partakes 

 of their incoherent nature and is ready to fall to pieces and to be recon- 

 structed by ever}^ new stimulus or suggestion. There is consequently 

 no connected train of thought and no stability of purpose. The thoughts 

 are like dreams. 



But derangement may affect the emotional department of the cerebrum 

 without the intellectual faculties being primarily involved. The constant 

 and unresisted stimulation of certain feelings causes the abnormal activ- 

 ity of the nervous elements involved to become habitually erethised. 

 People may become cross and irritable, passionate and violent; they may 

 become the chronic victims of excessive and self perpetuating grief or 

 sorrow, unless there be counteracting motives, either objective or sub- 

 jective. The objective motives are such as the environment supply in 

 resentment and forcible restraints imposed by society, or the diversion of 

 new occupations or surroundings. The subjective motives are those 

 supplied by one's own intellectual faculties and arise from the action of 

 certain of the internal sense organs. The control which the stimuli from 

 these exert upon the actions is what is denominated self-control (ch. 66). 

 To speak with precision, there is of course no such thing as self- control. 

 The stimuli from the " internal senses " arise from ideas which have 

 been constructed from sensations derived from environment in times 



