I go 



Saiuinelreforut. 



obtained by the writer with the moth Ahra.xits grossiiiiiriala and its variety 

 lacticolor, and the subsequent matings with the crossed offspring, described 

 in the paper in 'Science', are again exactly comparable, when the barred 

 character alone is taken into account. Space does not permit of a detrailed 

 account of these later results, which include every possible kind of mating; 

 it must suffice to say that they are completely explicable on the hypothesis 

 that the barred character is dominant, that B. P. R. males are homozygous 

 both for barring and for absence of the character which determines femaleness; 

 while B. P. R. females are heterozygous both for barring and for the female 

 determinant, and further that the barring 'factor" and the female deter- 

 minant cannot coexist in the same germ-cell. The writers express these 

 facts by the following formulae. Let B = barring, b its absence; F = the 

 female determinant, f its absence; then 



B. P. R. d = BfBf, producing gametes Bf, Bf. 



B.P.R 9 = BfbF, „ „ Bf, bP. 



C.I.G. 5 = bfbf, „ „ bf, bf. 



C.I.G. 9 = bfbF, ,. „ bf, bF. 



C.I.G. 9 X B.P.R. d will then give bfBf (= barred males), and bF.Bf 

 (= barred females), but B.P.R. 9 x C. I.G. J will give Bfbf (= barred males) 

 and bFbf (= non-barred females). With respect to the later crosses, in 

 which large numbers of chicks were reared from every possible mating, 

 the results were in accord with this hypothesis in every case, but not all 

 the non-barred birds were black as in the first cross. The details of other 

 colours are not yet given. In the first cross the barring of the cross-breds 

 was not quite identical with that of the parents, but evidence is given that 

 it is not intermediate in the true sense, but is due to the superposition of 

 another factor derived from the Indian Game. In the F.^ generation birds 

 barred like the pure B.P.R. reapjieared. 



In their paper in the Report of the Maine Agricultural Experiment 

 Station, the authors give details of a number of other characters in the 

 same crosses. Among these reference must be made to two which appear to 

 be sex-limited — shank colour and egg-production. Although both the parent 

 breeds are yellow- shanked, tlie l)lack females from the cross B.P.R. 9 x 

 C.I.G. 3 have black shanks; in the liarred males from this cross, and in 

 the barred offspring of both sexes in the converse cross, the shank is yellow. 

 An account of the behaviour of this character in the next generation is to 

 be awaited with interest, for there is apparently some relation between the 

 barred pattern and the yellow shank which requires elucidation. The 

 inheritance of egg-production also appears like sex-limited. Of the pure 

 breeds B.P.R. hens are good layers, C.I.G. poor; when crossed the barred 

 hens from the mating C. I.G. 9 x B. P.R. d are good layers like the paternal 

 breed, while the black hens from the converse cross are poor layers. This 

 suggests that the egg production is correlated with the barred plumage, 

 and is similarly transmitted in inheritance. For an account of other 

 characters, for example mortality of eggs and chickens, and the relations 

 of pea and single combs, the reader is referred to the original paper. 



Prof. T. H. Morgan's work with the fly Drosopliila provides a case of 

 sex-limited inheritance exactly the converse of that just described. Hitherto 

 almost the only case known of an animal organism in which a character 

 is transmitted from a heterozygous male only to his female offspring, is 

 in Man, where colour-blind ness and other eye-diseases, and also luumo- 

 phiFhu appear to behave thus. Now Morgan has discovered and worked 



