OVULATION IN BIRDS AND MAMMALS 217 



This is a familiar occurrence in many species of birds. In such 

 cases it is sometimes assumed simply that the maturing of eggs 

 is the cause of the nest-building. But the reverse is no doubt 

 equally true ; the activity of building and the contact with the 

 comfortable nest stimulate the development of eggs. The vis- 

 ceral and the peripheral activities of the bird are in reciprocal 

 relation ; each stimulates the other, and they proceed step by 

 step together. It is a case of '"circular activity" (Baldwin, 

 1906). Contact with the nest, under appropriate conditions, 

 exerts a powerful suggestive or an almost hypnotic influence 

 upon the bird, causing in her an emotional attitude which some- 

 how involves the ovaries. This attitude leads her to work further 

 upon the nest. Such work causes the stimulus from the nest to 

 be repeated. Thus the circular activity goes on and on. 



In the paper on the influence of the male on ovulation, I said 

 (Craig, 191 1, p. 300): 'The influence of the male in inducing 

 oviposition is a psychological influence." The reviewer of that 

 paper in the Psychological Bulletin (Washburn, 191 2, p. 309) 

 says : ' The word ' psychological ' is perhaps a little extreme here : 

 the tactile stimuli produced by the male's preening of the head 

 and neck of the female might operate reflexly." No doubt a 

 reflex arc is involved here as in all nervous action ; but it is 

 not a simple reflex. It is a reflex which is set working, not by 

 any one sense stimulus, but by the total situation including both 

 the totality of present sense stimuli and also memory factors. 



The one condition necessary to induce ovulation is that the 

 female should accept the attentions paid to her and throw her- 

 self into the mating and laying attitude. 1 When she does so, 

 her whole organism is affected. Her posture in standing and 

 her carriage in walking are greatly altered. She follows the 

 male to the nest and spends hours in dedicating and building that 

 structure (whereas a solitary female pays no attention to a nest, 

 under normal conditions). Her whole bearing shows intense 

 emotion, not violent, but deep. As the days pass, this manner 

 grows upon her, becoming an extreme attitude at the time of 

 egg-laying. 



1 The mating and the laying attitudes may be said to be two attitudes which 

 are subdivisions of one more general. In the ordinary course of the brood cycle, 

 the two are closely united. But I think I have seen each occur quite without the 

 other. In Case 2 (Craig, 1911), for example, there seemed to be no mating atti- 

 tude whatever, only a laying attitude. 



