president's address. — SECTION D. 257 



the transplantation and growth of mammalian ova within a uterine 

 foster-mother. The fertilized ovum of a rabbit transferred to the 

 oviduct of a rabbit of a different variety and developing in her uterus 

 gives rise to an animal that shows no foster-mother influence. But 

 this does not prove that, while the germ cells are maturing, they are 

 free from influence by the soma. 



Many workers have sought to obtain evidence oji this latter point. 

 Among the latest results published by workers in this field are those 

 obtained byW.E. Castle and John C. Phillips ("On Germinal Trans- 

 plantation in Vertebrates," Carnegie Institution of Washington, 1911). 

 These workers have been fully alive to the fact that the complete 

 removal of the original ovary is at least as difficult and delicate an 

 operation as the grafting of a new one from another animal ; and have 

 realized that, if results are to be of value, there must be no question as 

 to whether they may not be due to regeneration of the origi.nal ovarian 

 tissue. • They give a summary of prcvioii.s work, so far as the last fifteen 

 years are concerned, and they pay especial attention to the work of 

 Guthrie (1908) and of Magnus (1907), examining that work in the light 

 of their own. Guthrie exchanged the ovaries of black and of white 

 Leghorn chickens, and afterwards mated the grafted birds with birds 

 of the same breed. He obtained results which he interpreted as 

 showing that the foster-mother exercised an influence on the germ plasm. 

 Magnus made similar experiments with rabbits, and arrived at a 

 like conclusion. Castle and Phillips point out that regeneration of 

 old ovarian tissue is more common than successful transplantation, 

 that Guthrie had attached the new tissue to the site of the old, and 

 that, therefore, an autopsy could not show th-it regeneration had not 

 taken place ; and that the results obtained were just what would be 

 expected if the functioning tissue were regenerated tissue ; in short, 

 that the results were, in the main, such as would have been expected 

 had there been no operation. The results obtained by Magnus with 

 rabbits are shown to be open to criticism of a like Icind with a like 

 conclusion. Davenport, in repeating Guthrie's experiments, found 

 that regeneration occurred in all his cases. 



The series of experiments carried out by Castle and Phillips was, 

 in view of the difficulty of the operations, extensive. The cases hcr« 

 referred to are the most important of those in which offspring were 

 produced from grafted tissue. 



The left ovarj^ of an albino guinea-pig was removed, and the 

 ovary of a pure black guinea-pig was grafted on the cornu of the 

 uterus, not on the old site. Later, the right ovary was removed and 

 the ovary of a young black animal, not of the same ancestry as the 

 first, was grafted. Presumably this animal \v'as of pure breed, but 

 the question is not in this ca,se important ; for, as Ave shall see, the 

 right ovary was not concerned in the results obtained. After recovery 



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