STUDY— PHYSIOLOGICALLY CONSIDERED. 639 



out a recurrence of the suffocating fit ; but only the subsidence of 

 the inflammation — indicated by the diminished hoarseness of the 

 cough — gives a guarantee that the danger is past. 



STUDY— PHYSIOLOGICALLY CONSIDERED. 



By p. J. HIGGINS, M. D. 



THE ultimate element by means of which those processes that con- 

 stitute the mind are carried on, is the microscopic cell of the 

 gray matter of the brain. These gray nerve-cells, with the delicate 

 tissue in which they are imbedded, form a layer, from one sixth to one 

 twelfth of an inch in thickness, on the surface of the brain. This area 

 would be small, were it not disposed in folds or convolutions which 

 greatly increase its extent. It is upon the number and quality of these 

 nerve-cells, and the systematic exercise of their function, rather than 

 upon mere size or weight of brain, that the mental capacity of the 

 individual depends. 



The activity of the nerve-cells of the brain, in other words, de- 

 pends partly upon their inherent vitality or vigor of constitution, and 

 partly upon the quantity and quality of their blood-supply. They 

 may be stimulated into unwonted activity by an effort of the will or 

 the spur of excited consciousness ; but even in these cases, should the 

 strain last any length of time, the blood-supply is quickly and largely 

 increased. 



Skeptics may cavil, but the solid fact remains that strength of 

 intellect, like that of muscle, is frequently inherited. Capacities differ 

 from the beginning. For this reason, children can not be expected to 

 make equal progress under any system of teaching, any more than 

 horses upon a race-course. But, by persistent and judicious training, 

 the strength, speed, and endurance of all may be increased through a 

 steady and gradual development. 



In order that the teacher may utilize his efforts to the best advan- 

 tage, he should understand the laws of the mind's development, and 

 the influences that modify and regulate its activity. Mental philoso- 

 phy deals with the former — to explain some of the latter is the object 

 of this paper. 



The brain-substance may be touched, and even cut, with little or 

 no consciousness of sensation ; yet the gray nerve-matter is very deli- 

 cate in construction, and exquisitely sensitive to changes in its blood- 

 supply. Like other organs, it is exhausted by continued activity, and 

 needs rest in order to recuperate its vitality. All tissues wear more or 

 less by work ; that is, molecules of their cell-substance die and become 

 foreign matter, which must be cast off and replaced by new material. 



