92 THE RATE OF GROWTH [ch. 



Our curve of growth, whether for weight or stature, has a definite 

 form or characteristic curvature: this being a sign that the rate of 

 growth is not always the same but changes as time goes on. Such 

 as it is, the curvature alters in an orderly way; so that, apart from 

 minor and "fortuitous" irregularities, our curves of growth tend to 

 be smooth curves. And the fact that they are so is an instance of 

 that "principle of continuity" which is the foundation of all physical 

 and natural science. 



The curve of growth (Fig. 4) for length or stature in man indicates 

 a rapid increase at the outset, during the quick growth of babyhood ; 

 a long period of slower but almost steady growth in boyhood; as 

 a rule a marked quickening in his early teens, when the boy comes 

 to the "growing age"; and a gradual arrest of growth as he "comes 

 to his full height" and reaches manhood. If we carried the curve 

 farther, we should see a very curious thing. We should see that a 

 man's full stature endures but for a spell; long before fifty* it has 

 begun to abate, by sixty it is notably lessened, in extreme old age 

 the old man's frame is shrunken and it is but a memory that "he 

 once was tall"; the dechne sets in sooner in women than in men, 

 and "a httle old woman" is a household word. We have seen, 

 and we see again, that growth may have a negative value, pointing 

 towards an inevitable end. The phenomenon of negative growth 

 extends to weight also; it is largely chemical in origin; the meta- 

 bolism of the body is impaired, and the tissues keep pace no longer 

 with senile wastage and decay. 



We must be very careful, however, how we interpret such a Table 

 as this; for it records the character of a population, and we are apt 

 to read in it the life-history of the individual. The two things are 

 not necessarily the same. That a man grows less as he grows older 

 all old men know; but it may also be the case, and our Table may 

 indicate it, that the short men live longer than the tall. 



Our curve of growth is, by implication, a "time-energy" diagram f 

 or diagram of activity. As man grows he is absorbing energy 

 beyond his daily needs, and accumulating it at a rate depicted in 



* Dr Johnson was not far wrong in saying that "life declines from thirty-five"; 

 though the Autocrat of the Breakfast-table declares, like Cicero, that "the furnace 

 is in full blast for ten years longer". 



t J. Joly, The Abundance of Life, 1915 (1890), p. 86. 



