74 



THE RATE OF GROWTH 



[CH. 



anmial velocities already represented on our acceleration-curves, 

 we shall see that the one series of observations joins on very well 

 with the other ; and in short we see at once that our acceleration- 

 curve rises steadily and rapidly as we pass back towards the date 

 of birth. 



But birth itself, in the case of a viviparous animal, is but an 

 unimportant epoch in the history of growth. It is an epoch whose 

 relative date varies according to the particular animal: the foal 







cms. 



70 

 60 

 50 

 40 

 30 

 20 

 10 



2 4 



6 8 10 12 14 16 18 20 22 



months 



Fig. 7. Curve of growth (in length or stature) of child, before and after 

 birth. (From His and Riissow's data.) 



and the lamb are born relatively later, that is to say when develop- 

 ment has advanced much farther, than in the case of man ; the 

 kitten and the puppy are born earher and therefore more helpless 

 than we are; and the mouse comes into the world still earher 

 and more inchoate, so much so that even the little marsupial is 

 scarcely more unformed and embryonic. In all these cases ahke, 

 we must, in order to study the curve of growth in its entirety, 

 take full account of prenatal or intra-uterine growth. 



