486 GENETICS IN RELATION TO AGRICULTURE 



saved. . . . Like the other three young they were black, but with a few red 

 hairs among the black ones. They bore no white hairs .... 



Female 1970, daughter of the grafted albino, was mated with the albino male, her 

 father, and bore three young, two of which were albinos and one black with some red 

 hairs. If female 1970 had been the daughter of a pure-black mother, instead of a 

 grafted albino, we should have expected her to produce an equality of black and of 

 albino young. The observed result was the nearest possible agreement with this 

 expectation. 



A control mating of the albino male, 654, was made with a female of pure-black 

 stock. As a result there were produced two litters of young, including five individuals, 

 all black, with red hairs interspersed. This result shows that the red hairs found on 

 the six young of the grafted albino was due, not to foster-mother influence of the 

 grafted albino, but to influence of the male parent. The young of the grafted mother 

 were exactly such in color as the black guinea-pig which furnished the graft herself 

 might have been expected to bear had she been mated with male 654 instead of being 

 sacrificed to furnish the graft. The white foot borne by one of the young furnished no 

 exception to this statement. Spotting characterized the race of guinea-pigs from 

 which the father came. He was himself born in a litter which contained spotted 

 young whereas neither the pure-bred black race that furnished the graft nor the albino 

 race that received it was characterized by spotting. 



Inasmuch as the offspring of albino parents are invariably albinos, it is certain 

 that the six pigmented offspring of the grafted female were all derived from ova 

 furnished by the introduced ovarian tissue taken from a black guinea-pig. This tissue 

 was introduced while the contained ova were still quite immature, and it persisted 

 in its new environment for nearly a year before the eggs were liberated which produced 

 the last litter of three young. These young, like the earlier litters, gave no indication 

 of foste'r-mother influence in their coloration. 



The conclusion is forced upon us that the egg-cell during its growth 

 does not change in germinal constitution. Its growth is like the growth 

 of a parasite or of a wholly independent organism : what it takes up serves 

 as food; this is not incorporated merely in the growing organism, it is 

 made over into the same kind of living substance as composes the assimilat- 

 ing organism. Thus a critical experiment designed to test the relation 

 of soma to germ cells with respect to coat coloration failed to demonstrate 

 any direct interrelation whatever, and further experiments by the same 

 investigators indicated that for other factors also the foster-mother 

 exerted no influence whatever on the developing ova. The ovary of the 

 black guinea-pig produced exactly the same kind of ova in the body of the 

 albino as it would have produced had it remained in the body of the black 

 guinea-pig. Figs. 192 and 193 show the nine animals reported in this 

 experiment. The full record of this experiment of Castle and Phillips' 

 shows in detail the character of critical investigation which has been 

 brought to bear on various phases of the question of the inheritance 

 of acquired characters. 



In passing, it should be mentioned that a few previous experiments 

 on germinal transplantation appeared to indicate the existence of some 

 influence of the foster-mother. Of these the experiments of Guthrie on 



