502 Miscellaneous. 



impregnates a whole series of ova arranged in the ovary in the order 

 of their maturation, from the egg which has hurst its capsule to 

 those which have to undergo a fortnight or three weeks of ovarian 

 evolution before dehiscence) present a ready field for experiment. 

 In these the various degrees are so clearly marked that there is no 

 room for confusion. If the theory is well founded, the first eggs of 

 each series should furnish males, and the last females. 



In M. Coste's experiments this result has not been attained. Of 

 five eggs laid after a single copulation, the first two gave males, 

 the third a female, the fourth a male, and the fifth a female. The 

 experiments were continued by M. Gerbe. A hen, after impregna- 

 tion, laid fourteen, and, after a second impregnation, eleven eggs, of 

 which the order of laying was noted. Of the first series, the second, 

 seventh, eighth, and tenth eggs gave male birds ; the fifth, ninth, 

 and eleventh female, and the remainder were infertile or abortive. 

 Of the second series, the second, third, sixth, and seventh furnished 

 females ; the fourth and eighth males ; the first and the last three 

 were infertile, and the fifth was broken during incubation. Thus it 

 appears that, in the fowl, males and females are produced indiffer- 

 ently, and not in an order corresponding with the maturity of the 

 eggs, and that M. Thury's theory does not apply to these birds. 



If it be held that the impregnation does not take place while the 

 ovum is still retained within its capsule, but that the spermatozoids 

 lie in wait upon the surface of the organs, to impregnate the ova 

 during their passage towards the oviduct (after the analogy of In- 

 sects), it must still be admitted that every impregnated ovum must 

 have attained its extreme limit of maturation. 



But in the Mammalia a phenomenon occurs which has no parallel 

 in birds : copulation precipitates the dehiscence of the capsule of 

 the ovum ; so that ova may be at pleasure made to separate from the 

 ovary two or three days sooner or later, according as the females are 

 allowed access to the males at the commencement or towards the 

 end of the rut. In the former case, the products should be female ; 

 in the latter, male. 



To test this view, M. Gerbe has made some experiments on rab- 

 bits. A female rabbit in which the rut was but just commencing, 

 so that she resisted the approaches of the male for several hours, 

 was isolated after copulation, and killed in four weeks. The right 

 horn of the uterus contained three, and the left one nine young, of 

 which the sexual relations were as follows : — 



In the right horn : the first, female ; the second, male ; and the 

 third, female. 



In the left horn : the first, male ; the second and third, female ; 

 the fourth, fifth, and sixth, male ; the seventh, female ; and the 

 eighth and ninth, male. 



A second rabbit, far advanced in heat, was killed four weeks after 

 copulation. The right horn of the uterus contained five, and the left 

 seven young. These were — 



In the right horn : the first, female ; the second, male ; the 

 third, female ; the fourth, male ; and the fifth, female. 



