SEX-LIMITED INHERITANCE IN POULTRY 17 



and they only, were realized. Thus the conbination white 

 hackle — white wing-bar (pure Dark Brahma type) did not occur. 

 In r2 from Dark Brahma grandfathers two kinds of males are 

 possible, viz., those like the pure bred Dark Brahma and hybrids. 

 Of the two males that matured one belonged to the Dark Brahma 

 type and one to the hybrid type but the Brown Leghorn combi- 

 nation did not reappear. Both sets of experiments thus speak 

 strongly for the conclusion that all sex-limited characters are 

 linked together in the sex-chromosome. 



Finally, our study throws light on the question whether all 

 secondary sex-character's are sex-limited — in the sense of being 

 carried in the sex-chromosome. For if they are we should expect 

 the female hybrid to inherit such characters from her father's 

 race only. But as we have seen, this is not the case. The de- 

 tails of penciling, stippling, and shafting show clear evidence of 

 blending of conditions from both parental races, in the first hy- 

 brid generation. Figs. 7 and 8 show how like the feather pattern 

 is in the pullets of reciprocal crosses. This leads us, provision- 

 ally, to classify sex-dimorphic characters into two classes: a, 

 characters whose development is controlled primarily by deter- 

 miners located in the sex-chromosomes and, h, characters whose 

 development is specially influenced or modified, probably by 

 secretions of the sex-glands. 



January 19, 1912 



LITERATURE CITED 



Bateson, W. 1909 Mendel's principles of heredity. Cambridge, England, 396 

 pp. 



Davenport, C. B. 1911 Another case of sex-limited heredity in poultry. 

 Proc. Soc. for Exper. Biology and Medicine, vol. 9, pp. 19, 20. Dec. 

 20, 1911. 



DoNCASTER, L. AND Raynor, G. H. 1906 Breeding experiments with Lepidop- 

 tera. Proc. Zool. Soc, London, vol. 1, p. 125. 



Durham, F. M. and Marryat, D. C. E. 1909 Inheritance of sex in canaries. 

 Rept. Evol. Com., vol. 4, pp. 57-60. 



GooDALE, H. D. 1909 Sex and its relation to the barring factor in poultry. 

 Science, vol. 29, 1004, 1005, June 25. 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY. VOL. 13, NO. 1 



