212 THE BIOLOGY OF THE SEASONS 



must be tested afresh when applied to another order of facts, 

 such as human conduct. 



Returning to our figure of an ascending and a descending 

 curve, we see that the period of human adolescence is an 

 ill-defined part of the up-grade after juvenile characters 

 have been for the most part lost, when adult characters 

 are being put on, when childish ways and childish things 

 are being put away and the life is taking definitive shape, 

 when sex-impulses begin to be more than whispers and the 

 limit of growth is within sight. 



Our first note relates to the difficult question of growth. 

 From studies on animals it seems clear that growing is an 

 uphill business ; it is an ascent whose gradient becomes 

 always steeper and more difficult. It illustrates what is 

 called the law of diminishing return. At the same time, 

 though the juvenile rate of growth is never afterwards 

 attained, and in most cases is not even approached, there 

 is often a remarkable reacceleration during adolescence. 

 Like a good horse, the organism puts on a spurt as it gets 

 near the top of the hill. 



Professor C. S. Minot compares the business of growing 

 to the building of a wall by one man. As the wall rises, the 

 man becomes more and more tired ; he has to lift the stones 

 higher ; he builds more and more slowly. The wall goes on 

 growing, but at a steadily diminishing rate. We may 

 say, perhaps, that just as he gets near his limit, beyond 

 which he cannot reach, he braces himself up for a rapid 

 effort. 



Now, there is a corresponding acceleration associated with 

 human adolescence, and we do well to remember it, for 

 it means that the energies of the organism are necessarily 

 to some extent preoccupied with its own business. It is 

 an intricate and difficult problem]: there is increasing 

 stability and increasing instability, there is great vigour 



