208 CERTAIN LAWS OF VARIATION 



tained in the case of man, we saw that between the 15th 

 and 19th years the rate of growth was only about 1- 

 2400th part of that obtaining in the third week of 

 foetal existence. Now granted that any effect pro- 

 duced by a changed environmental condition at this 

 early period dwindled down to even a tenth of its origi- 

 nal amount by the time the adult stage had been 

 reached, yet the organism, as far as the permanent 

 effect of environment is concerned, would still be 240 

 times more sensitive in the one case than in the other. 



Striking evidence in support of this conclusion that 

 retardations of growth, once produced, are never totally 

 eradicated, has been recorded by Galton.* A friend 

 of his took monthly measurements of the circumference 

 of his children's heads during the first few years of 

 their lives, and by plotting them out on paper, obtained 

 curves of growth. These curves were regular on the 

 whole, but each of them showed occasional halts, which 

 were found to coincide in point of time with the various 

 infantile diseases the children had experienced. These 

 illnesses had therefore arrested the development, and 

 this " had not been made up for by after growth." In 

 fact " disease had drawn largely upon the capital, and 

 not only on the income of their constitutions." 



A few of Minot's data afford similar evidence. In 

 one of his guinea-pigs, No. 34, the increase in weight 

 was quite normal at first, but then absolutely ceased 

 from the 90th to the 110th day. After this it con- 

 tinued normally as before, but the animal never suc- 

 ceeded in recovering its loss, and after two years 

 weighed only about two-thirds as much as the other 

 *" Inquiries into Human Faculty," p. 235. 



