Eugene Howard Harper 5 



for mating are put together, egg-laying ordinarily ensues at the end 

 of a rather definite period, at the least eight days. The female functions 

 are held in abeyance till the proper stimulus is received from a mate. 

 The maturing of the egg is so exclusively a female function that it 

 seems odd at first thought that an apparent exception should occur to 

 the rule. Of course, we know that the final maturation of the egg, or 

 the giving off of the polar bodies, awaits in most animals the act of 

 fertilization. But here the effect is produced upon the egg by the 

 entrance of sperms. How mating itself and the act of copulation could 

 influence the ripening of the egg in the ovary is another problem. In 

 this connection the curious fact must be mentioned that two female 

 pigeons placed in confinement together may both take to laying eggs. 

 The function of ovulation is in a state of tension, so to speak, that 

 requires only a slight stimulus, "mental" apparently in this case, to 

 set the mechanism to working. At any rate, it is impossible to regard 

 the presence of sperm in the oviduct as an essential element of the 

 stimulus to ovulation, although it may have an important influence in 

 the normal case. Our attention is directed to the various and complex 

 instincts of the male which come under the head of courtship, both 

 before and after mating is effected, as furnishing a part of the stimulus 

 to the female reproductive organs. 



Phylogenetie considerations would lead us to consider the peculiar 

 habits of the pigeon as recently acquired. The retention of ova in 

 the unmated female, is in particular not very firmly fixed, as the facts 

 stated show. The habits of the common fowl are certainly more primi- 

 tive. In monogamous birds it might be expected that the function of 

 ovulation would be adjusted so as to take place only after mating, inas- 

 much as it is probable that in a state of nature mating may be delayed 

 for various causes, and the production of an unfertilized egg is no trifling 

 loss, as in the mammal. In polygamous birds mating is sure to occur, and 

 the female functions may be adjusted for continuous ovulation, with 

 the practical certainty that in nature no unfertilized egg will be pro- 

 duced. 



The complex reproductive instincts of the pigeon, displayed in their 

 highest . form in the male, are matters of common observation among 

 those who have observed pigeons, and need not be dwelt upon at great 

 length. 



As is weU known, the strutting of male pigeons is not simply a fea- 

 ture of courtship and rivalry among males. It is continued until egg- 

 laying begins, and is accompanied by a less active similar manifestation 

 by the female. It is in fact an accompaniment of the whole period 



