GENERAL PRINCIPLES OF BREEDING. 83 



aside as unreliable. They appear periodically; 

 and the lapse of a decade is sufficient to pass 

 in review, through the agricultural press, the 

 whole brood upon any given subject bearing 

 upon agriculture. That of controlling the sex 

 of offspring has, ever since the days of Aristotle, 

 been one of the most fruitful topics of discus- 

 sion, and the various theories that have been 

 advanced appear and reappear with perennial 

 vigor. These theories may be briefly summa- 

 rized as follows: 



1st. A strong mental impression on the part of the parents, 

 but especially of the mother, at the time of conception, will 

 determine the offspring. 



2d. The concentration of the attention of the dam on her 

 peculiarly feminine qualities, at the time of sexual union, 

 will secure female progeny. 



3d. If the amorous desires of the male are stronger than 

 those of the female the progeny will be a female, and vice 

 versa. 



4th. The development of the foetus in the right side 

 (horn) of the womb will secure a male, and in the left side a 

 female. 



5th. The point of origin of the artery of the testicle from 

 the main abdominal trunk (aorta) will determine the sex of 

 the majority of the offspring, the male sex predominating 

 in proportion as the origin is more anterior. 



6th. The male germ is supplied by the right testicle or 

 ovary, and the female by the left. 



7th. The excitation of one side or the other of the system 

 of the male at the time of coition will determine the sex of 

 the young. 



8th. The persistent selection for breeding purposes of 

 females which yield one sex mainly, and of males from 

 females of the same kind, will finally secure a race produc- 

 ing a great excess of the sex in question. 



