330 PRINCIPLES OF STOCK-BBEEDING. 



that before the fourth month the sex cannot be said 

 to be confirmed, and that it will prove male or female 

 as the tendency to the paternal or maternal type may 

 predominate." ' 



It should be remarked in this connection that the 

 testicles and the ovaries are formed from the same 

 embryonic structure, and at an early stage of develop- 

 ment it is impossible to determine which form of the 

 generative apparatus is to be produced. According 

 to this theory, the male offspring should resemble the 

 father, and the female offspring should resemble the 

 mother ; but we have seen that the transmission of 

 resemblance is frequently from the father to the 

 daughter, or from the mother to the son ; and some 

 physiologists even claim that this is a law of heredity 

 that has few exceptions. 



Dr. Flint has presented a provisional theory that 

 does not differ essentially from that of Sir Everard 

 Home. He says : " It may be that when just enough 

 of the male element unites with the ovum to secure 

 fecundation, or when it might be said that the female 

 element predominates, the foetus is a female; and, 

 when a greater number of spermatozoids unite with 

 the vitellus, the male sex is determined. 



" Such an idea, however, is purely theoretical ; and 

 the question of the determination of sex presents thus 

 far hardly the shadow of a satisfactory explanation." ' 



Mr. Wright's directions for breeding the sexes of 

 chickens at will is apparently based upon the idea 



1 "Principles of Breeding," by Goodale, p. 89; Morton's "Cyclo- 

 paedia of Agriculture," vol. i., p. 336. 



8 "Physiology of Man "" Generation," vol. v., p. 346. 



