78 MR. R. STAPLES -BROWNE ON [Feb. 18, 



F. 2 Generation. 



As Avill be seen by the Table no black birds were raised in 

 Exp. 3. This experiment came to an untimely conchision early 

 in the breeding season owing to the accidental death of the S • 

 No other (S raised in Exp. 1 Avas then living. It seems likely, 

 however, that if the mating could have been continued black 

 birds would have appeared. Exp. 4 was continued foi' two years, 

 nnd, in addition to the bii'ds included in the table, a young bird 

 was hatched which died in the nest at the age of ten days. It 

 was dark in colour, but Avhether it would eventually have been 

 black or blue could not at that age be distinguished. 



Black birds in the F. 2 generation. — ^Of the fifteen black birds 

 raised five showed no trace of white, the other ten having some 

 white feathers. Birds entirely black were not tested at this point 

 of the experiment, but in the crosses between Bai'bs, Fautails, 

 and Nun pigeons it was shown that extracted blacks in F. 2 bred 

 true {v. Exps. 40 & 41). Those having Avhite feathers were 

 noticed to show more white than the birds of the F. 1 genei^ation. 

 In addition to having Avhite feathers on the same parts of the 

 body as the preceding generation, these birds frequently showed 

 white on the head aud throat, also on the Avings, and more espe- 

 cially on the flight-feathers. The black, hoAvever, always greatly 

 predominated in the plumage. In one case there Avere only a 

 A'ery feAv Avhite feathers on one thigh. 



Mue birds in the F. 2 generation. — In addition to the general 

 description of the blue birds already giA^en, it may here be stated 

 that the bird bred in Exp. 5 (No. 19) diflered from those in 

 Exp. 3 in having the blue coloui' much darker. In the young 

 I'aised from the subsequent matings of the ofispring of this bird, 

 the dark blue colour Avas \"eiy marked, so that it AA^as possible to 

 pick them out at sight in an aA'iary containing many blue birds. 

 This bird shoAved two AAdaite feathers on the rump w^hich Avere 

 afterwards moulted out. Experiment, hoAveA^er, proved that it 

 did not contain Avhite {v. Exp. 13). Of the blue birds raised in 

 Exp. 3 two (Nos. 1 & 14) showed no Avliite, Avhile the third 

 (No. 51) had a few Avhite feathers at the vent. Further matings 

 proved that two of these birds contained Avliite recessive, Avhile 

 the other did not (see Exps. 9, 16, & 30). Of the four F. 2 blues, 

 therefore, tAvo Avere homozygous to that colour. 



Fed birds in the F. 2 generation. — A general description of 

 these birds has already been giA-en. It seems desirable to post- 

 pone all further details until the iuA-estigation is more advanced. 



WJiite birds in the F. 2 genei"ation. — Of the ten extracted Avhite 

 birds six shoAved no coloured feathers, and four shoAved a little 

 colour. From Exp. 4 tAvo bii-ds Avith coloured feathers Avere 

 raised. Of these one (No. 1) showed four or five feathers of a 

 brownish or i-eddish tinge on the neck, these were afterwards 

 moulted out. The other (No. 15) had the head and throat 

 ticked with some reddish feathers. These birds Avere not bred 

 from. In Exp. 5 one Avhite bird (No. 5) Avas produced Avhich 



