The Role of the Chromosomes 



225 



been given. One of tlic most striking of these color changes 

 occurs in the male scarlet tanager, which during the breeding 

 season wears a uniform of brilliant scarlet with black wings; 

 after which he assumes a dull olive drab like the female, 

 which he wears during the winter, resuming his brilliant garb 

 in spring. Another bird with a pronounced difference be- 

 tween summer and winter plumage is the male bobolink. 

 We hail with joy his return to our northern fields in spring, 

 with his bright livery of black, buff and cream, and his ring- 

 ing, cheery song. In the fall, when in his dull drab coat 



Effect of Diet on Body Form in- Amblystoma 



Fig. 1, young cannibal after full meal. Fig. 2, typical larva. Figs. 

 3-5, young cannibals. Fig. 6, normal larva, typical of the ordinary 

 specimens among ■which the cannibals were found. From Powers, 

 "Morphological Variation and its Causes in Amblystoma tigrinum. " 

 Studies from the Zoological Laboratory of the University of Nebraska, 

 Vol. IV, No. 71. 



he gathers in flocks of thousands upon our marshes, we shoot 

 him as the plump little "reed bird"; while over the rice fields 

 of the Carolinas, upon his return from his summer sojourn 

 in the North, he meets an even worse reception from the rice 

 grower as his inveterate enemy, the "rice bird." 



Immediately following the breeding season, i. e., at the 

 time of the fall molt, birds are usually in poor condition 

 both in respect to feathers and flesh. Some male tanagers 

 and bobolinks in the New York Zoological Gardens were pre- 

 vented from breeding for one season, during which time they 

 remained in full song and excellent physical condition and 

 retained their full breeding plumage. About a month previous 



