1908.] INHERITAXCE OF COLOUR IN PIGEONS. 71 



been introflucerl by the Fantail. It is jDointed out below that one 

 of the Fantails in the strain used (Lee $ 7) showed a black 

 feather. The relation between this bird and Fantail S 23, the 

 bird used in Exp. 2, is shown in a pedigree of the Fantails. 

 Although several pairs of pure-bred Fantails were kept, " splashed" 

 birds never appeared in their offspring. An opportunity appears 

 to have arisen in the crossing, however, by which this latent 

 character was able to manifest itself. 



A further series of experiments was undertaken on the crossing 

 of two distinct white breeds, Tumblers and Fantails. Here again 

 blue colour was produced in the F. 2 generation. An account of 

 this cross is included in the present paper. 



For testing the various Mendelian ratios the pigeon is not a 

 thoroughly satisfactory subject to work with, unless the experi- 

 ments can be carried out on a very extensive scale. To insure 

 the desired mating it has been found necessary to keep each pair 

 of birds in a separate aviary. The number of pairs kept is there- 

 fore limited. Further, the number of offspring produced by a 

 pair of pigeons is comparatively small, seldom exceeding ten in 

 any one year. In a few cases, when a ratio between the numbers 

 of the various types of offspring produced by a cross was desired, 

 the .same mating has been continued for a second year. 



In the following account the ordinary Mendelian terms 

 are used. 



The Barb Pigeon. (Pigeon polonais.) 



In 'Animals and Plants under Domestication,' Darwin describes 

 the points of the Barb thus: — "Beak short, broad, deep; naked 

 skin round the eyes broad and carunculated ; skin over nostrils 

 slightly swollen." It was hoped that these characters might be 

 traced in the crossbreds, but some ditHculty was experienced in 

 obtaining accurate measurements, and the attempt was abandoned. 

 The "eye-wattle" or cere, moreover, does not attain to its 

 maximum development until the bird is in its fourth year. The 

 Barb is a " self-" or whole-coloured j)igeon, and is found in black, 

 red, yellow, dun, and white. Of these black is the commonest. 

 Blue Barbs are exceedingly rare, and are seldom if ever used by 

 breeders for crossing with the other colours. 'No wing- or tail- 

 bai'S, or chequering are found in the usvial colours. The eye- 

 wattle is bright red. The iris is generally white, sometimes 

 orange, and in white Barbs is black. The beak and claws ai-e 

 desired by breeders to be white ; there is, however, a tendency for 

 black Barbs to have the beak tipped with black, or even horn- 

 coloured beaks. This was the case with the specimens used in 

 these experiments. Four black Barbs were obtained ; tliose used 

 in Exps. 1 and 34 were bought through a poultry advertising 

 paper, and their origin is unknown. Barb 2 -i No- 7, used in 

 Exp. 2, was obtained from Mr. J. Wilkins of Swindon. This 



