EXAMINATION OF OBSERVATIONS OF GUTHRIE AND MAGNUS. 17 



breeding- capacity. It does not prove him to have been homozygous in 

 white. If W 1 was homozygous, only white chicks would be expected, what- 

 ever the character of the white rooster. 



We have now examined in detail the two pairs of transplantation exper- 

 iments which form the entire basis of Guthrie 'e assumption that the foster- 

 mother may in a case of homoplastic transplantation affect the character of 

 the offspring. In no one of the four cases does the hypothesis that the 

 transplanted ovary functioned offer less difficulty than the hypothesis that 

 only regenerated ovarian tissue functioned. In two of the four cases the 

 advantage is overwhelmingly with the latter hypothesis. That ovarian 

 tissue might easily be left behind in exchanging ovaries between two ani- 

 mals Guthrie frankly admits in a recent paper (1910), citing experiences 

 of his own to show just how this might come about. He still maintains, 

 however, his belief in foster-mother influence, because, we believe, of a fail- 

 ure to grasp fully the laws of inheritance of the character which he used as 

 a criterion. A similar failure is shown by the comment which he makes 

 in Science (1909) upon the case which we have more fully described in this 

 paper (Group I) . Referring to our failure to detect foster-mother influence 

 in the young borne by female 27, he says : "Had the operated pig been 

 bred to a male of the same strain as the pig from which the engrafted ovary 

 was obtained * * * characteristics in the offspring indicative of such 

 influence might have been obtained." Now, suppose the operated pig had 

 been so bred, what result might have been expected? Exactly that which 

 was obtained from the mating with an albino, only we should have been left 

 in uncertainty, precisely as in Guthrie's own experiments, as to whether 

 the pigmentation of the offspring was due to maternal or paternal influence. 

 By the'mating with an albino male all such uncertainty was eliminated, 

 since it was rendered sure that if the offspring were pigmented they could 

 have derived this character from no other source than the transplanted 

 ovary of the little black guinea-pig. 



Our case does not prove that foster-mother influence is impossible. No 

 such claim is made for it. But our observations do show that evidence such 

 as Guthrie has presented is wholly without value in establishing foster- 

 mother influence, and that in one specific case, the first critical case on rec- 

 ord, we believe, no foster-mother influence is detectable. 



In view of our own experiments on guinea-pigs, in which the source of 

 the tissue which liberated the ova is fully established and in which no foster- 

 mother influence is detectable, we may fairly ask that the experiments with 

 fowls be repeated on adequately controlled material before we accept the 

 interpretation which Guthrie has given to his results.* 



*While this paper was in press our attention was called to the fact that Dr. C. B. 

 Davenport (1910, Proc. Soc. Exp. Biol. Med., vol. vn, p. 168) had indeed repeated Guth- 

 rie's experiment with fowls, on material adequately controlled and of known pedigree. 

 The result was that in every case castration was incomplete and ovarian regeneration 

 occurred, leading to the production of young showing no influence of the introduced 

 graft. 



