PHASES IN THE LIFE OF THE INDIVIDUAL 705 



no statistical data on which to found any knowledge, but from the 

 third month onwards there are a few records available. The 

 diagram shows that from the third to the fourth month the increase 

 in growth is 600 per cent., after which it quickly drops until, during 

 the last month of pregnancy, it is barely twenty per cent. 



GKOWTH OF THE BODY AFTER BIRTH 



The rate of growth from birth to maturity has been investigated 

 most fully by Minot 1 in the case of the guinea-pig. When this 

 animal is born it is far advanced in development, the period ol 

 gestation being unusually long. Immediately after birth there is a 

 lessening in the power of growth, a fact which Minot ascribes to the 



\ 



Z 5811 n 23 29 J535 45 



75 90 105 120 135 ISO 165 ISO 195 2IOiiajfc> 2*1 



FIG. 175. (From Minot's Problem of Age, Growth, awl Death, 

 G. S. Putnam & Sons, and John Murray.) 



physiological shock from which the organism suffers as a consequence 

 of being born. After two or three days, however, the young are 

 fully recovered, and are capable of adding over five per cent, to their 

 weight in a single day. By the time they are seventeen days old 

 they are only able to add four per cent, to their weight, and by the 

 time they are twenty-four days old, less than three per cent. When 

 they have been born forty-five days, they can add only a little over 

 one per cent, to their weight ; when ninety days old, less than one 

 per cent., and 'still less as they grow older, until when about a year 

 old they attain their full size. The curves in the accompanying 

 diagrams show the daily percentage increments in weight in male 

 and female guinea-pigs respectively, as ascertained by Minot. It is 

 seen that the curve for the females is very similar to that for the 



1 Minot, "Growth and Senescence," Jour, of Physiol, vol. xii., 1891. "Age, 

 Growth, and Death," Popular Science Monthly, vol. Ixxi., 1907. 



23 



