EXAMINATION OF OBSERVATIONS OF GUTHRIE AND MAGNUS. 15 



Since in Guthrie's experiments the character of the germ-cells furnished 

 by the mother is in question, we may conveniently group the experiments 

 according - to the character of the male used. 



Series I. Rooster Black. 



Black hen Bl, control, mated with the black rooster, had 13 black chicks 

 with "grayish-yellow breasts and throats, and frequently the under sur- 

 faces of the tips of the wings were light colored as well, but the plumage on 

 the entire dorsal surface was always solid black." 



Black hen B 3 and white hen W 3 had their ovaries exchanged and were 

 later bred to "the black rooster." Black hen B3 produced six black 

 chicks, four apparently normal, but two " with white legs." We are not 

 told whether this whiteness was of down or final plumage, but the state- 

 ment is added: "In regard to the chicks from this hen described as ordi- 

 nary black, some doubt exists as to whether the ventral light-colored area 

 described for normal black chicks was not lighter and greater in extent in 

 all cases than in the normal chicks." Since this ventral lightness is of 

 down only, not of later plumage, we are led to infer that the description 

 of the abnormal black chicks was also based on the down colors. And 

 since, further, white chicks are not white in the down, but blacks chicks are 

 light be\ow in the down, it seems that Guthrie's real meaning is that the 

 two abnormal chicks had light legs (not white legs) in the down. But 

 this does not indicate whether the adult plumage in that region was to 

 be black or white. If this reasoning is correct, then the only difference 

 between these two chicks and ordinary black chicks is that they perhaps 

 had more extensive light ventral areas in the down plumage, the light area 

 extending onto the legs. This has no relation whatever to the plumage 

 condition of the white race from which the graft was taken and can not 

 fairly be assigned to that source. 



If the six chicks were produced from regenerated ovary (i. e. , from germ- 

 cells of the black hen not removed at the operation) we should expect them 

 all to be black, as they were. If they were produced from transplanted 

 ovarian tissue without foster-mother influence, we should expect them all 

 to be white, which they were not. For the white of Leghorn fowls, accord- 

 ing to Bateson and Davenport, behaves as a dominant character in crosses 

 with black, cross-breds being white or white spotted sparingly with black. 

 Unless, therefore, we grant that these six chicks came from regenerated 

 ovarian tissue of the black mother herself, we are forced to assume that the 

 ovarian tissue transplanted from the white hen completely changed its char- 

 acter from white to black within the black hen. It is a hypothesis at least 

 equally plausible to suppose that no cells were changed in character, but a 

 few were overlooked in the castration. 



White hen W 3 , having received the ovary from black hen B 3 , was also 

 mated with ' 'the black rooster. ' ' She produced twelve ' 'white chicks with 

 black spots on the dorsal surface of the head, neck, wings, back, or on the 



