8o 'Journal of Comparative Neurology and Psychology. 



After days of copulation and nest-building, all of which are con- 

 trolled by cooing and other ceremonies, two eggs are laid and the 

 birds enter upon fourteen days of brooding. 



D. Tlie daily cycle. 



The male and the female take turns very regularly in sittiug on 

 the eggs. Each time when one bird relieves the other, there is a 

 ceremonial communication between them. 



C". TJie hroocling cycle, continued. 



After the eggs are laid, the birds are guardedly quiet when near the 

 nest, but there is no diminution of conjugal affection (page 74). 



The hatching of the eggs, and the movements of the young under 

 the breast, are strong stimuli to the parents (page 73 ). 



The parents may even add at this time a new call to their vocab- 

 ularly, a call to the young to feed (pages 43, 44, 76). 



The parents, while still feeding the young, gradually work up, 

 by cooing and other performances, to that pitch of excitement which 

 is needed to start a new brood cycle (page 76). 



B". The annucd cycle, continued. 

 At the end of the summer, especially when the molt begins, the 

 birds have not sufficient energy to work up to the beginning of a ne^v 

 brood cycle. Thus brooding stops. 



A". The life cycle, continued. 

 Pigeons do not reach their maximum breeding powers until an age 

 of about three years. 



The lengih of life is not definitely known. 



