6 Varietäten, Descendenz, Hybriden. 



The authors point out that this phenomenon is superficially 

 comparable with that seen in Sweet Peas and Stocks where two 

 albinos crossed together give a coloured F v In the Fowls we are 

 not dealing with albinos, since the birds all have pigmented eyes, 

 and in the Silkies the buff of the down is an indication of the pre- 

 sence of some pigmentation. The R-white however contains some 

 factor which is complementar}^ to that present in the Silky, and 

 the two are needed for the production of fully coloured plumage. 

 The Silky crossed with the White Rose-comb Bantam gives only 

 whites in F l and hence it is likely that of the two complementary 

 factors one only is present and is common to both of these types. 

 If this is so the Rose-comb should give only coloured offspring when 

 crossed with the R-white. Disparity of size prevents the direct cross, 

 but the authors have tested the point indirectly by mating the F, 

 J from the Rose-comb X Silky with a £ R-white. The mating gave 

 28 birds all fully coloured, from which it may be inferred that the 

 Rose-comb white, if crossed with the R-white, would behave like 

 the Silky in giving only coloured birds. 



The authors regard the Dominant white as containing an addi- 

 tional factor, D, whose action is to prevent or diminish the produc- 

 tion of colour by the two complementar}'- factors. The results upon 

 which these conclusions are based are given in detail , together 

 with analyses of the inferred gametic constitutions of the various fowls. 



The inheritance of the pale brown down colour and the brown 

 stripe in the chicks of the Game Bantams is shown to be explicable 

 on the assumption that the allelomorphs concerned are 1. presence 

 and absence of brown colour, and 2. presence and absence of brown 

 stripe; the factor for brown-stripe being epistratic to that for pale 

 brown. A point of interest is that both the brown striped and the 

 pale brown chicks develope into adults practically identical in the 

 colour of the plumage. 



The authors show that in respect of colour the Breda fowl is 

 similar to the well known case of the Andalusian, viz., the blues 

 crossed together throw blacks, blues and splashed whites approxi- 

 mately in the ratio 1:2:1. The blacks breed true. This is confirmed 

 by crosses between the Andalusian and Breda. 



Davenport's view of the recessive nature of the Silky plumage 

 is confirmed. 



A case appeared in which the offspring of one white </ crossed 

 by a Brown Leghorn hen consisted of a mixture of fully coloured 

 birds and mottled birds. No extensive experiments have been car- 

 ried out with this mottled character, but the authors bring forward 

 evidence which leaves little doubt that it behaves as a simple do- 

 minant to the fully coloured. R. P. Gregory. 



Durham, Fl. M., A preliminary Account of the Inheri- 

 tance of Coat-Colour in Mice. (Rep. Evol. Comra. Roy. Soc. 

 IV. p. 41—53. 1908.) 



In addition to results largely confirmatory of previous work on 

 the inheritance of coat-colour in mice, Miss Durham has studied the 

 relation of the dense to the dilute coat-colours on a considerable 

 scale; and in regard to the pied varieties, the existence of a domi- 

 nant pied condition has been demonstrated. The relation of the 

 pigmentation of the eye to that of the coat has been investigated 

 and in part elucidated. 



