Experimental Study of Growth 



245 



follows a period of slower growth ; and, vice versa, those that fall 

 behind make it up later, if they remain in good health. A young 

 guinea pig may lose one third its weight from intestinal catarrh, 

 and make the loss good later. ''It is probable that the same is 

 true of man, and that the usual and even the severer illnesses of 

 childhood and youth do not greatly affect the ultimate size of 

 the adult." PagHani shows that children brought up in poverty 

 and undersized will recover in the most surprising manner if 

 placed under favorable circumstances. 



"It has been asserted by Carpenter, Spencer, and others that 

 the functions of nutrition and reproduction are in principle 

 opposed to one another, because reproduction makes such a de- 

 mand upon the parent for material that the supply of nutrition 

 and growth of the parent is lessened." Unfortunately for this 

 philosophic generalization the premises are wrong — the grow- 

 ing animal is not growing at its maximum of assimilative power. 

 It has been shown that young female guinea pigs grow about the 

 same whether they are carrying young or not. Minot concludes 

 that "gestation does not represent a tax upon the parent but a 

 stimulus — it does not impede growth, but on the contrary 

 favors it." Spencer's ^^ dogmatic assertions" concerning the 

 opposition of growth and reproduction are open to justly severe 

 criticism. 



A guinea pig reaches its full size by the end of the first year, 

 when it weighs about 775 grams. A rabbit is also full-sized a 

 year after birth, and weighs 25000 grams. Man may be said to 

 be full grown at the end of twenty-five years, and has then an 

 average weight of 63000 grams. If we add to these times the 

 length of the period of gestation, and divide the weights by these 

 numbers, we obtain the average rate of growth a day. 



365 -f 67 days = 1.82 per diem 



365 -h 30 days = 6.30 per diem 



9139 + 280 days = 6.69 per diem 



The calculation shows that man is larger than the rabbit because 

 he grows for a longer period ; but the daily increments are nearly 



