486 ON GENERATION. 



nearly perfect, in one case in the right in another in the left 

 horn of the uterus ; in twin cases in both horns. 



At this time, too, the male embryo is readily distinguishable 

 from the female by means of the organs of generation. These 

 parts are also very conspicuous in the human embryo, and 

 make their appearance at the same time as the trachea. 



Males and females are met with indifferently in the right 

 and left horn of the uterus. I have, however, more frequently 

 found females in the right, males in the left horn ; and I have 

 made the same observation in does that carried twins, as well 

 as in the sheep. It is certain, therefore, that the right or left 

 side has no appropriate virtue in conferring sex ; neither is the 

 uterus, nor yet the mother herself, the fashioner or framer of 

 the foetus, any more than the hen is of the pullet in the egg 

 which she incubates. In the same way as the pullet is formed 

 and fashioned in the egg by an internal and inherent agent, is 

 the foetal form produced from the uterine ovum of the hind and 

 doe. 



It is indeed matter of astonishment to find a foetus formed 

 and perfected within the amnion in so short a space of time 

 after the first appearance of the blood and punctum saliens. 

 On or about the 19th or 20th day of November this punctum 

 first becomes visible; on the 21st the shapeless vermiculus or 

 maggot that is to form the body of the future animal is per- 

 ceived ; and in the course of from six to seven days afterwards 

 a foetus so perfect in all its parts is seen, that a male can be 

 distinguished from a female by the organs of generation, and 

 the feet are formed, the hooves being cleft, the whole having a 

 mucous consistency and a pale yellowish colour. 



The substance of the uterus begins to be extenuated imme- 

 diately after the appearance of the embryo ; contrary to what 

 takes place in the human female, whose uterus grows every day 

 thicker and fleshier with the advancing growth of the foetus. In 

 the hind and doe, on the other hand, the more the embryo aug- 

 ments the more do the cornua of the uterus assimilate themselves 

 to the intestines ; that horn in particular in which the foetus is 

 contained looks like a bag or pouch, and exceeds the opposite 

 one in dimensions. 



The ovum or conception, thus far advanced, and with its in- 

 cluded foetus perfectly distinct, has still contracted no adhe- 



