794 POPULAR SCIENCE MONTHLY. 



this have to psychical force? The modern view of physiology de- 

 mands that "we shall interpret the beginnings of every activity of the 

 individual in terms of protoplasm. It is difficult at first sight to 

 understand the relation between the muscle cell and the gray cell of 

 the brain. It is not so difficult, however, when we remember that 

 both were originally undifferentiated protoplasm, having common 

 properties: both were able to contract, and both to co-ordinate. 

 Gradually the one cell specialized so that this contracting function 

 superseded and dominated all the others, while in the other case it 

 was the co-ordinating or directing or automatic function that was 

 given the first place. Whatever of vigor there was in the original 

 protoplasm we find in the specialized cell of the adult body. Vigor is 

 at bottom one thing, and we find that vigorous psychical force tends 

 to be found in the same individuals in which vigorous physical force 

 is found. When an undifferentiated bit of protoplasm contracts — as, 

 for example, an amoeba — what happens? This is the simplest term 

 of muscular contraction. All we can now say is that the mass does 

 not change, the total volume remains constant, the ultimate particles 

 rearrange themselves. This may be done so as to overcome resist- 

 ance, and thus becomes work. That these particles should be able to 

 arrange themselves, in opposition to mechanical force exerted upon 

 them from the outside, indicates that there is something besides 

 mechanical force within the cell, something besides physical force. 

 It can hardly be regarded as mere chemical force, for in the case of 

 many of the lower forms of even single-celled organisms there is 

 a high degree of adaptation of means to ends, indicating psychical 

 activity. To work out this relation of muscular to psychical force 

 would, I think, throw light upon some of the interesting questions as 

 to why some races are fitted to survive and others are not; as to why 

 weak-minded individuals are so often those with fiabby muscles; and 

 as to why there is such a close connection between vigorous doing 

 and strong willing. These matters are related not merely to the 

 individual, but to the whole race, and, indeed, to the whole series of 

 which the human race is but a part. 



2. Of how much importance is physical exercise in the develop- 

 ment of the brain? The modern school of psychologists tell us that 

 from one third to one half of the brain surface has muscular func- 

 tions; that this great fraction of the brain is concerned with making 

 muscles contract, each little spot being concerned with its own muscle 

 or group of muscles. This does not prevent these parts of the brain 

 being also used in other ways. This we know less about. We do know, 

 however, that it is necessary to have muscular exercise of any group 

 of muscles, if the corresponding nerve center is to be developed. 

 Careful examinations have been made of the brains of those who had 



