66 MODES OF RESEARCH IN GENETICS 



of the probable condition of that character in 

 the progeny of that organism. 



Thus, to take some concrete instances by way of 

 illustration, if one breeds a Cornish Game cock 

 bird to a Barred Rock female, the female offspring 

 resulting will not be, in respect to plumage, 

 color pattern, in the slightest degree like either 

 parent. On the contrary they will be solid black 

 in color. 1 A knowledge of the somatic condition 

 of the parents, in such a case, no matter how 

 detailed it might be, would, in advance of the 

 actual breeding test, give no clew whatever as to 

 the probable somatic condition of its offspring. 

 Yet, in its procedure of correlating parent and 

 offspring in respect to somatic characters, the 

 "law of ancestral inheritance" definitely assumes 

 that the somatic condition of the one may be 

 taken as a valid and reliable criterion of the other. 

 Many cases like that just cited might be given 

 from existing Mendelian literature. Indeed, it 

 may be said that nearly all experiments in crossing 

 plants or animals furnish illustrations of the 

 general principle that the somatic condition of a 

 character may be a most unreliable criterion of its 

 probable behavior in inheritance. 



It may be objected that the types of cases cited 

 in the preceding paragraph are hardly a fair basis 

 for the criticism of the law of ancestral inheritance 



1 For details see Pearl, R., and Surface, F. M. Arch. f. Ent. 

 Mech.y Bd. 30, pp. 45-61, 1910. (Roux Festschrift.) 



