218 



The Journal of Heredity 



the wcij^ht of the indixidual eggs laid 

 by the hen. Such slight changes as 

 were noticed can be explained by the 

 fact that the weight of a hen's eggs 

 tends to diminish toward the end of her 

 laying season. 



2. It could not be fovuid that the 

 cock ]jroduced any effect whatc\'er on 

 the form (proportion of length to 

 breadth) of the eggs. Walther says 

 that the weight and length of an egg 

 are very closely correlated, so this result 

 is only what would be expected from 

 result"No. 1. 



3. The glossiness of surface of the 

 eggs did not seem to be at all affected 

 by the cock. This is not such a critical 

 case as some of the others, because the 

 differences in glossiness of the eggs of 

 the pure races used in the experiment 

 are not so great and sharply distin- 

 guished. As far as it goes, however, the 

 examination of this point utterly fails 

 to show any trace of xenia. 



4. As to the influence of the cock 

 on the color of egg shells, the experiment 

 was not entirely conclusive. It was 

 started with another purpose in mind, 

 and sufficient care was not taken to 

 choose breeds of fowl that were sharply 

 distinguished in the color of their eggs. 

 The results, such as they are, tell 

 against rather than for an influence of 

 the cock on the color of the egg shelT, 

 but Walther does not claim that they 

 are final. 



THE CONCLUSIONS 



In conclusion, Walther says: "The 

 study of the question whether the male 

 bird is in a position to influence the egg 



shell characteristics in the direction of 

 those that mark his own breed or si:)ecies, 

 was taken up to determine the accuracy 

 of the investigations previously men- 

 tioned, purporting to show that xenia 

 occurred in the animal kingdom." As 

 far as Holdefleiss' results are concerned, 

 Walther thinks they are hardly worth 

 considering. As for the results from von 

 TscheiTnak's crosses of canary species, 

 Walther says, "My own results have 

 contradicted them, as far as size, shape 

 and glossiness of the eggs is concerned, 

 showing not the slightest trace of in- 

 fluence on the part of the cock. For 

 the question of influence on the color 

 of the egg shell, my researches unfor- 

 tunately are not in a position to throw 

 much light. I think that both these 

 alleged cases of xenia in birds' eggs are 

 from ever}' point of \'iew utterly 

 unsafe grounds for drawing any sweep- 

 ing conclusion." 



Few biologists would 1)0 likely to 

 dissent from Walther on this point, 

 that no sweeping conclusions should be 

 drawn from this evidence ; and Walther's 

 own results must share the same fate. 

 Von Tschermak's experiments with ca- 

 naries must be regarded with respect 

 until they are contradicted or explained 

 away, but the evidence of xenia in 

 poultry is certainly not adequate. 

 American poultry breeders do not, on 

 the whole, entertain a belief in xenia in 

 their flocks, and as far as the present 

 evidence is concerned, their skepticism 

 seems to be justified. The question is 

 a recent one, and much work may yet 

 be done on it, but until such work is 

 done, xenia in fowls must be considered 

 an open question, at most. 



Barred Pattern in White Fowls 



In the note at the bottom of page 149, Journal of Heredity, AjM'il, 191.^ (Vol. 

 VI, Xo. 4), it is stated that "Further analytic breeding proves that this barring 

 is carried in the germ-plasm of the White Leghorn, not the White Plym.oulh Rock." 

 The last line should have read, "of the White Leghorn as well as the White Plvmouth 

 Rock." 



