14 ON GERMINAL TRANSPLANTATION IN VERTEBRATES. 



Group V. 

 In this group are placed fifteen cases in which the grafted animals died 

 or were lost without any autopsy being- made upon them. Only six died 

 as the immediate result of the operation, four of the six being cases in which 

 a ventral route to the ovaries was attempted. 



The results obtained by us from ovarian grafting in rabbits are largely 

 negative. Seventeen animals have been operated upon. 



One rabbit, in which an autograft was made onto the uterine horn on each 

 side, gave birth four months later to two young. Nine months later a 

 second operation showed both these autografts functioning ; they were 

 removed and ovaries from another rabbit were placed in their stead; atrophy 

 of the external genitalia soon resulted and the animal was a few months 

 later discarded.* 



Of the other homoplastic cases, two showed regenerated tissue at the 

 original ovarian site, one of these having had young. Of the remainder, 

 six died or were lost, while three showed complete atrophy of the external 

 genitalia and three more are still alive, manifesting normal sexual instincts 

 but having borne as yet no young. 



On the whole the results obtained from rabbits are very similar to those 

 obtained from guinea-pigs. Autografting is evidently not difficult, and 

 may be followed by the birth of young. In heteroplastic grafting, regener- 

 ation of ovarian tissue at the original site is a commoner event than growth 

 of the introduced tissue, the latter result not having been certainly obtained 

 in our experiments with rabbits, though the former has been obtained in 

 two cases. 



5. CRITICAL EXAMINATION OF THE OBSERVATIONS OF GUTHRIE AND MAGNUS ON 



SUPPOSED FOSTER-MOTHER INFLUENCE. 



A cursory reading of Guthrie's evidence may well lead one to accept 

 without question his conclusions: (l) that in his fowls the transplanted 

 ovaries have functioned, and (2) that the foster-mother has influenced the 

 character of the young; but critical analysis of the evidence fails to sub- 

 stantiate either conclusion. Since the ovaries exchanged were transplanted 

 to the original ovarian site, it would have been impossible by autopsy to 

 ascertain whether the ovary present was transplanted or regenerated 

 tissue. But regeneration is a much commoner result of such operations 

 than successful transplantation, as our results with guinea-pigs show; and 

 in the absence of other evidence the interpretation of the functioning ovary 

 as a regenerated ovary should be preferred. The only other evidence we 

 have is that derived from the character of the offspring. 



*Simple inspection of the external genitalia appears to be sufficient in rabbits to show 

 whether or not the uterus is functioning normally. 



