Development and Care of the Young 187 



weight twelve-fold; it develops keen senses and complex in- 

 stincts, acquires a serviceable and comely dress, and is ready for 

 flight. 



This was well illustrated by a nest of four Cedar-birds, one 

 of which hatched _ 

 in my hand on 

 the twelfth day 

 of August; three 

 which lived to 

 grow up we re 

 weighe d and 

 measured daily 

 for a p e r i o d of 

 fifteen days, from 

 birth to the time 

 of flight. The 

 eggs from which 

 these birds were 

 born were nearly 

 of the same size 

 and weight (a t 

 time of hatching 

 weighing 38^ 

 grains or nearly 

 T V ounce ), but 

 by the end of the 

 first day marked 

 differences in rate 

 of growth had ap- 

 peared, and were 

 constantly main- 

 tained. 



The weight of 



the most vigorous nestling was doubled on the first day, more 

 than trebled on the second, and nearly quadrupled on the third. 

 On the twelfth day, when it weighed approximately one and one 

 fifth ounces, and had increased in weight thirteen-fold, it left 



Male grampus, Corydalus cormitus : full size, 



