174 



THE RATE OF GROWTH 



[CH. 



month by month during the Antarctic season, of the sizes of pregnant 

 females and the foetuses they contain; and from these I draw the 

 following averages: 



Antarctic blue whales; length of mother and of foetus 

 (Season 1938-39) 



2126 



83-8 



^ .- 



NOV 



DEC 



JAN 



FEB 



MAR 



Fig. 43. Pre-natal growth of blue whale. Average monthly sizes, 

 from data in International Whaling Statistics, xiv, 1940. 



The observations are rough but numerous. At the lower end of 

 the scale measurements are few, and the value indicated is probably 

 too high; but on the whole the curve of growth taUies with other 

 estimates, and points to birth about June or July, and to conception 

 about the same time last year (Fig. 43). The mean size of the 

 mother- whales does not alter during the five months in question; 



