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THE POPULAR SCIENCE MONTHLY 



but there is possibly a variation in other organs, such as the leg or 

 tarsus, but it is difficult to obtain reliable measurements on some of 

 these parts. The most vigorous nestling (No. 1) more than doubled 

 in weight on the first day, more than trebled on the second, and more 

 than quadrupled on the third, while on the twelfth day, when it left 



Fig. 29. Young Cedarbird, No. 1 of table, shortly after hatching, lying on side, 

 cicatrix of umbilicus showing on abdomen ; weight 5 grams. August 10, 1901. 



the nest it had increased its initial weight seventeen-fold. What ten 

 days will do for the young cedarbird on the score of appearance may 

 be seen by comparing Figs. 29 and 30, the first of which shows nestling 

 No. 1 when about two hours old. The data on which these curves are 

 based are given in the following table. 



Fig. 30. The same Cedarbird (on left) as shown in Fig. 29, ten days later with 

 birds Nos. 2 and 3 from the same nest. All show the crouching tendency, in evidence 

 of fear. 



Kuhlmann, 2 who has recently published an interesting study of the 

 development of the instincts and intelligence in certain altricious birds, 

 in particular the turtle dove, the brown thrush and the red-wing 

 blackbird, finds the rate of growth quite similar to that shown for the 



2 The Psychological Review, Monograph Series, No. 44, November, 1909. 



