3IO THE GROWTH OF THE BRAIN. 



studied showed marked differences. Five years later 

 another set of records showed the same differences. 

 Similar illustrations might be indefinitely multiplied. 

 At any moment the active body-cells contain a mass of 

 substances capable of producing energy by their 

 decomposition, yet the mass present at any moment 

 is but a trifling fraction of that which will be built up 

 and broken down in the course of a normal lifetime. 

 This capacity to build up food-stuffs into its own 

 substance is the peculiarity of the living cell, as con- 

 trasted with a crystal or a machine, and it is a question 

 of great interest to learn whether in ourselves, by our 

 own foresight, and within the limits of a lifetime, it can 

 be increased. Thus it would be of importance could we 

 determine whether the greater store of available energy 

 in those who seek by hygienic care to cultivate their 

 effective force is to be counted as an actual addition to 

 their powers, or whether it is simply that fraction of 

 inherited energy which has been rendered available by 

 more effective expenditure. Probably both, changes 

 follow. Yet, so seldom are the natural forces normally 

 expended, that it is difficult to get the data for a 

 judgment. 



In the body-form deviations from the mean are 

 familiar, and their implication appreciated. The build 

 of the "sprinter" is something quite different from that 

 of the lifter of heavy weights. Or, taking deviations 

 which are more marked, any part head, arms, legs, 

 chest may be too large or too small for the other 

 portions of the body, and it is abundantly evident 

 that these failures in proportion, if those of excess, may 

 easily reach the point where the offending part becomes 

 too large to be correctly nourished or controlled by the 

 remainder of the body ; or, if those of defect, where the 

 part must work under excessive strain, in order to con- 



