18 ON GERMINAL TRANSPLANTATION IN VERTEBRATES. 



The work of Magnus demands no extended discussion. Into a black 

 rabbit were introduced the ovaries of a white one. The grafted black rabbit 

 was then mated with a white male rabbit. Two litters of young resulted 

 which consisted in part of black animals and in part of white ones. There 

 is no question of an intermediate or modified character in the young, such as 

 Guthrie would have us believe occurred in his experiments. If any foster- 

 mother influence was exerted at all, it was such as changed the character 

 of germ-cells completely from the albino to the fully pigmented condition. 

 But this supposed influence manifested itself in part only of the germ-cells 

 subjected to the new somatic environment; the others were unaffected. 



An alternative interpretation is plainly possible. The ovary observed 

 at the autopsy of the grafted black rabbit may have been regenerated from 

 fragments of ovarian tissue not removed by castration. We do not under- 

 stand that there was anything in the observed position of the organ decisive 

 either for or against such an interpretation. 



It is known from studies of Hurst and of Castle that the albino condition 

 in rabbits is a Mendelian recessive to black. The grafted black rabbit may 

 have been a heterozygous black, containing albinism as a recessive char- 

 acter. In that case, if the black rabbit had not been operated upon, but had 

 been mated with an albino male, we should have expected that young would 

 be produced half of which were black, half albinos. This is substantially 

 the result observed. Accordingly, so far as the character of the young is 

 concerned, there is no reason to think that they were produced from intro- 

 duced ovarian tissue rather than from regenerated ovarian tissue of the 

 black rabbit herself. 



But if we adopt the interpretation that the observed ovary was really an 

 introduced ovary, we encounter this difficulty. If introduced egg-cells 

 through somatic influences were changed in character so that they produced 

 black young instead of white ones, why were not a// the egg-cells so affected? 

 Were they not all subject to the same somatic influences? On the whole, 

 therefore, we meet fewer difficulties by interpreting the observed ovary as 

 a regenerated ovary rather than as a transplanted ovary. 



6. A REVIEW OF THE LITERATURE ON GRAFTING OF TESTICLES. 



The work on testicle grafting is less voluminous than that on ovarian 

 grafting. In a general way some of the more uncritical of the early inves- 

 tigators reported results of a positive nature; but later work along the same 

 lines gives results of an entirely different character. 



Berthold in 1849 interchanged testicles between two cocks after castrating 

 both animals. The organs, one in each animal, were not sutured. Five 

 months later they were found grown against the colon in both cases, and 

 full of active spermatozoa. The cocks retained their sexual instincts. 



Mantigazza (i860), experimenting on frogs, found living testicular tissue 

 in grafted animals after a period of 70 days. He thought that the tissue 

 preserved its structure. Bizzozero (1868) confirmed these results. 



