i8o Journal of Comparative Neurology. 



ive parentage, is the accompaniment of arrested development, 

 or is the penalty left by previous disease. 



As the result of the first of these causes, to-\vit, the capacity 

 of the cell to assimilate nourishment, some types of cells have a 

 very limited functional capacity, within the limits of safety, and 

 slight power of resistance. They are easily overworked and 

 their possessors constitute oftentimes the mental invalids which 

 abound to enliven the tedium of the busy practitioner. Still 

 other types of cells are essentially short-lived, coming early to 

 maturity, possessing their maximum of functional power for a 

 comparatively short period, and soon falling into decay and the 

 degeneracy of premature old age Hysteria is an excellent ex- 

 ample of a form of mental disorder due to the third class of cell 

 defects, and has its origin in defective mhibitory control of cell 

 energy. That recovery from mental disease is so seldom satis- 

 factory, and the tendency toward recurrence after one attack is 

 so great, is due to the changed nutrition of the brain cells and 

 their dmiinished capacity to assimilate nourishment. It is to be 

 borne in mind also that the large lymph spaces around the 

 blood vessels of the brain and about the brain cells, and the con- 

 nection seen between these in some cases, at least, indicate the 

 importance which we must attach to the rapid elimination of 

 waste products from contact with the cellular elements. The 

 products of cell metabolism are extremely inimical to the normal 

 activity of the cells, and their toxic effects upon the system have 

 been fully established. 



To understand more clearly cell nutrition and cell energy 

 and their delicate adjustment and interdependence, we must re- 

 member that there is an extreme susceptibility in these carrying 

 blood vessels, to stimulation from the activity of the cells them- 

 selves, and that their calibre and the supply of material which 

 they convey, vary with the slightest variation of cell activity, or 

 their stimulation from the exterior. With this varying calibre 

 and the consequent changes in the blood pressure come the 

 modifications in the relation which the nutritive supply bears to 

 the activity of the cell. There is a genuine hyperaemia of the 

 brain cortex during its period of activity, which seems essential 

 to the rapid evolution of energy, and during which both the 

 amount of nourishment consumed and of waste products pro- 



