BEHAVIOR OF VERTEBRATES 433 



Craig (10) shows that stimulation of a female dove by the 

 male without copulation was followed by oviposition. "The 

 present paper goes to show that the stimulus to the whole pro- 

 cess of egg development and laying is a psychic (neural) stim- 

 ulus not dependent upon the introduction of sperm." (P. 305.) 



Chappellier's (6) paper is a brief report upon a systematic 

 study of the sex organs and sex life of hybrid birds. He dis- 

 cusses the apparent sex indifference in female hybrids obtained 

 from crossing canaries and goldfinches. He mated one of these 

 females with a canary. Nest-building began shortly after mating. 

 The process of nest construction was desultory and lasted through 

 the egg-laying period. The first egg was laid more than two 

 months after mating. During 92 days she laid 16 eggs in a 

 very irregular fashion and ate each of them in turn within one 

 or two days after laying it. Although mated with an ardent 

 male, she was entirely indifferent to him. This passivity in 

 hybrid females is connected with a rudimentary condition of 

 the ovaries, which are represented by three or four small form- 

 less masses. 



Herrick (12) devotes nearly 100 pages to the nest structures 

 and the activity of nest-building in birds. The series of papers 

 is very comprehensive. He treats of the function of the nest, 

 the classification of nests on the basis of behavior, analysis of 

 increment nests, variations in nests of certain birds, nidification, 

 intelligence in nest-building and the origin of the instincts of 

 incubation and nidification. The discussion of nidification is 

 based chiefly upon the writer's field observations of behavior in 

 nest-building. The author is conservative in his discussion of 

 the presence of intelligence in nest-building: " Instinct furnishes 

 the springs of action in birds." These are exceedingly complex 

 and in a high degree adaptable. This innate equipment takes 

 the place in a large measure of mind or intelligence. He finds 

 evidence of a wide group of associations between sense impres- 

 sions and motor impulses. Habits of approaching and leaving 

 the nest are quickly formed. Apparently one finds occasional 

 adjustment of means to end where difficulties arise. 



In regard to the origin of instincts of incubation and nidifica- 

 tion, Herrick reaffirms his former position : the instinct to hide 

 supplemented by that of guarding the eggs is responsible for the 

 later instinct of incubation where guarding with concealment 



