L. DONCASTBR 97 



F^ X F^ both with excess of black, but with more white than in C Ca II, 

 of four youug, three were white-with-black and one black-with-white. 

 In two other matings also between black-with-white birds (G Ca II 

 and N) white-with-black was produced. In one case where a similar 

 mating between white-with-black birds was made (CC'al, F^ from 

 C X F„ from Cal) 2 white-with-black and 2 black-with-white appeared. 

 It appears then that birds with excess of black can be produced from 

 those with excess of white, and vice versa. But the only mating.s from 

 which pure blacks were produced were those in which two black-with- 

 white birds were paired together (C Ca /J and GCalV). The latter 

 of these pairings consisted of an F^ cock from mating C, paired with his 

 own black daughter produced in the mating CCall; these two produced 

 1 white-with-black, 3 black-with-white and 2 black. 



Since these results seemed somewhat confusing, and might perhaps 

 be partly due to the impurity of the original stock of black fantails, 

 I obtained two well-bred black fantails from fanciers which had no 

 white speckling on the webs and paired them with whites (K and L). 

 In mating K (white J x black (/) two young were produced, one of 

 which died before it was fully fledged, but it appeared to be completely 

 black. The other was patched black and white, the patches of colour 

 being larger than in Series C and D. The white hen then died, and on 

 pairing the black cock with another (mating K.,), one black and white 

 mottled young one was produced. In the converse cross (Z) one young 

 one only was produced which was black-with-scattered white feathers, 

 and most of the tail white. The pied F^ bird from K mated with the i^i 

 from L gave 9 young, 4 white, 3 black-with-white, 1 black with one 

 white tail feather and 1 blue and white, with black wing and tail- 

 bars. The Series K and L thus differ from C and D in producing one 

 full black -fi bird, and in producing no white-with-blacks. They differed 

 also in that most of the black-with-white birds had the central tail 

 feathers white, while those in the Series C and D were almost always 

 black. 



The results appeared at first very perplexing, especially the absence 

 of blacks in F.,, and the fact that black-with-whites and white-with- 

 blacks when paired together can each produce the other. These facts 

 indicate that two or more pairs of allelomorphs must be present, and an 

 explanation may possibly be sought on lines similar to those suggested 

 by Mudge with regard to the inheritance of piebaldness in Rats. If we 

 assume that pattern depends on two pairs of characters, P for piebaldness 

 and S for full (self) colour, each allelomorphie with its absence ( p and s), 



