T1VIPAUOUS ANIMALS. 40? 



These results appear still more surprising, when we consi- 

 der that both the absorbing vessels of the foetus, and like- 

 wise its nervous system, appear to act but feebly ; as viru- 

 lent poisons injected into the pleura, peritoneum, or cellular 

 tissue, do not appear to produce any decidedly deleterious 

 effects *. 



The circumstances on which the sex of the foetus de- 

 pends, though removed beyond the reach of observation, 

 have nevertheless been the subject of conjecture. Many 

 years ago, Sir F. H. EYLES STILES, in reference to mo- . 

 noecious and dioecious plants, advanced the opinion, that 

 " in all cases where the male and female organs are found 

 separate, the defect is not in the flower, which I suppose 

 to be originally instructed with the rudiments of the or- 

 gans of both sexes, but that it arises from some circum- 

 stances in the plant, that determines it to blow the one or- 

 gan and not [the other f." An opinion somewhat similar 

 is adopted by Sir EVEIIARD HOME, with regard to qua- 

 drupeds. He supposes " the ovum, previous to impreg- 

 nation, to have no distinction of sex, but to be so formed 

 as to be equally fitted to become a male or female foetus ; 

 and that it is the process of impregnation which marks the 

 distinction, and conduces to produce either testicles or ova- 

 being turned on one side, at an angle nearly approaching to a right angle : 

 and what may deserve notice, all of them turned the same way, towards the 

 left side. I was urged to rear one of them as a curiosity ; but, conceiving 

 that it might grow up rather a disgusting object, 1 had the whole destroyed, 

 preserving only the one which appeared to be perfect. That one I kept 

 about a month, when it was seized, as well as the mother, with a disorder 

 which greatly enfeebled it ; and to save the parent, 1 destroyed the offspring. 

 But it was previously discovered, that this also had the tail distorted, and 

 turned aside at a considerable angle, although free from the knot which 

 distinguished the other four." Lin. Trans, vol. ix. p. 323. 



* M. MAGENDIE, Precis El. ii. p. 448. 

 ~f- Phil. Trans, vol, lv. p. 250. 



