May 26, 1911] 



SCIENCE 



817 



overlooked this statement. And I may say 

 that all subsequent statements regarding my 

 results have been made from the same stand- 

 point. 



In attempting to interpret my results from 

 the Mendelian standpoint, to overcome the 

 difficulty in concluding that in no instance 

 the offspring were derived from engrafted 

 ovarian tissue, Castle can only see his way 

 clear by speculating as to the result that 

 might have followed had I employed two 

 white cocks in the matings, one cock being a 

 half-breed. But he assumes that only one 

 white cock was used, for, as he points out, 

 I use the expression " the white rooster." But 

 since a point of doubt has been raised as to 

 whether one or more white cocks were em- 

 ployed, and since Castle claims that I make 

 no specific statement on this point, I would 

 refer to the table on page 565 of the paper 

 appearing in the Journal of Experimental 

 Zoology, which is headed " weights of the 

 chickens were as follows," in which the ex- 

 periment numbers of the individuals, both 

 male and female, used in the experiment are 

 given, together with their weights. 



In respect to the evidence of soma influence, 

 this was observed in the offspring directly 

 from the transplanted ovaries. Therefore, it 

 is not open to the same doubt as in the case 

 of more indirect or circumstantial evidence. 

 But supposing that such offspring had been 

 bred, and supposing the offspring resulting 

 from this mating (grand chicks) had or had 

 not presented characteristics indistinguishable 

 from the offspring obtained by straight breed- 

 ing or of hybrids obtained by crossing un- 

 operated fowls of the breeds employed, such 

 results could not affect the conclusions of 

 foster-mother influence in the first generation. 

 It would only show that in the particular 

 individuals presenting feather markings indi- 

 cating soma influence, that similar feather 

 markings were or were not transmitted to 

 their offspring, or that individuals pre- 

 senting no such markings might or might 

 not transmit evidence of soma influence to 

 the next generation. Again, the fact that the 

 markings in all cases were not uniform in the 



offspring of the first generation, in no way 

 invalidates the results. For all exact knowl- 

 edge of soma influence must of necessity 

 spring directly from experimental results. 

 Therefore, it can not be assumed that all such 

 offspring must present similar characters 

 either to be acceptable as evidence that an 

 engrafted ovary may preserve its reproductive 

 function, or that such offspring may be influ- 

 enced by the somatic tissues of the host. 

 That is to say, it is not permissible to assume 

 that all of such offspring would be influenced 

 in the same direction or to the same degree. 

 Nor can it be assumed that evidence of soma 

 influence can be demonstrated in other com- 

 binations of fowls, much less in different spe- 

 cies of animals. 



Seemingly a lack of insight into the under- 

 lying physiological principles in such experi- 

 mentation has led Castle and his collaborator 

 into a misunderstanding, and therefore into 

 stating their belief that my interpretation of 

 the results, and my criticism of a statement 

 of theirs regarding evidence of soma influ- 

 ence,* was due to a failure to grasp fully the 

 laws of inheritance of the character which I 

 used as a criterion. But this is more of a 

 personal matter and therefore of no general 

 interest. 



These writers call attention to the fact that 

 Davenport attempted to repeat my experi- 

 ments on fowls, with the result that in every 

 ease spaying was incomplete, and the young 

 from such operated hens showed no influence 

 of the introduced graft. This is far from 

 being an argument against the acceptance of 

 my conclusions, as all that it shows from his 

 interpretation is that the ovaries were incom- 

 pletely removed in his experiments. But as 

 a matter of fact, his experiments and results, 

 while meagerly reported," such as they are, 

 might as weU lead to the conclusion that he 

 obtained very strong evidence of soma influ- 

 ence. That is, the chicks so closely re- 



* ' ' Guinea-pig Graft-hybrids, ' ' Science, N. S., 

 1909, XXX., 724. 



° Davenport, ' ' Inheritance of Plumage Color in 

 Poultry," Proceedings of the Society for Experi- 

 mental Biology and Medicine, 1910, VII., 168. 



