ABSENCE OF XENIA IN OSTRICH EGGS 



South African Ostrich Hens Mated with North African Ostrich Cocks Lay Eggs 



Characteristic of Their Own Species — No Signs of Male Influence on 



the Egg Shells — No Xenia 



J. E. DuERDEK, M.Sc, Ph.D. 



Professor of Zoology, Rhodes University College, Grahamstoivn; Officer-in-charge, 

 Ostrich Investigations, Grootfontein School of Agriculture, Middlehurg, C.P. 



IN T\-Ul Joi RXAL OF Heredity for 

 May, 1915, Vol. vi. No. 5, appears 

 a review of certain in\^estigations on 

 xenia in fowls. By xenia is there 

 understood "that the eggs laid by 

 a hen are influenced as to size, shape 

 and color by the cock with which .she 

 is mated." The occurrence of xenia 

 in plants is first noted. Here cross- 

 pollination is often found to have an 

 influence on the character of the seed 

 obtained directly from the cross, a 

 result which is shown to be readily ex- 

 plained from the peculiar formation of 

 the endosperm, where one of the two 

 nuclei from the foreign pollen is involved 

 in its production. The reviewer then 

 discusses the various instances which 

 have been adduced as showing some 

 paternal influence on bird's eggs, espe- 

 cially those of Holdefieiss and Walther 

 with fowls and Armin von Tschermak 

 with canaries and finches. The conclu- 

 sion arrived at is that "the evidence of 

 xenia in poultry is certainly not ade- 

 quate." The article closes with the 

 statement that "the question is a 

 recent one, and much work ma}^ yet be 

 done on it, but until such work is done, 

 xenia in fowls must be considered an 

 open question." 



Some recent work in crossing the 

 North African and South African ostrich 

 upon which the present writer has been 

 engaged for some time affords ver}- 

 conclusive evidence in support of the 

 above contention and, although dis- 

 tinctly negative in character, seems well 

 worthy of record, since it represents 

 such a clear cut test case. In 1912 the 

 Government of the Union of South 

 Africa imported 132 specimens of the 



North African ostrich from Nigeria 

 with the object of possibly improving 

 the domesticated Cape strains, built 

 up during the past fifty years of ostrich 

 farming from the original South African 

 wild bird. The imported birds, origi- 

 nally captured by the Arabs from wild 

 nests, were stationed at the Groot- 

 fontein School of Agriculture, and the 

 breeding experiments in connection witli 

 them were placed in charge of the writer. 



Zoologists generally recognize four 

 species of the ostrich genus, Struthio: 

 The North African ostrich, 5. cameltis, 

 Linn.; the South African ostrich, 5. 

 australis, Giuney; the East African 

 ostrich, 5. massaiciis, Naumann; and 

 the Somali ostrich, 5. molybdophanes, 

 Reichenow. The two last mentioned 

 are however not well established species, 

 appearing to represent only intermediate 

 types of the other two. On the other 

 hand the northern and the southern 

 birds have clearly defined distinguish- 

 ing characteristics as regards bodih' 

 size and color, nature of the egg, and 

 other minor features. Observing them 

 side by side as can be done at Groot- 

 fontein, without any intermediate forms, 

 no one would hesitate in assigning them 

 specific distinction. 



As in all other birds the eggs from 

 the same ostrich and also from different 

 ostriches vary within certain limits as 

 regards size, shape and surface charac- 

 ters. But beyond these fluctuating 

 variations several well defined and 

 constant differences distinguish the egg 

 of the North African from that of the 

 South African ostrich; and it is the 

 presence of these which affords such a 

 decisive test as to the occurrence or 



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