Ciiap. VI. THEIR REVERSION IN COLOUR. 207 



of bine and chequered Ibirds ; but it will now be seen that 

 when two birds belonging to distinct races are crossed, 

 neither of which have, nor probably have had during many 

 generations, a trace of blue in their plumage, or a trace of 

 wing-bars and the other characteristic marks, they very 

 frequently produce mongrel offspring of a blue colour, some- 

 times chequered, with black wing-bars, &c. ; or if not of a 

 blue colour, yet with the several characteristic marks more 

 or less plainly developed. I was led to investigate this 

 subject from MM. Boitard and Corbie 26 having asserted that 

 from crosses between certain breeds it is rare to get anything 

 but bisets or dovecot pigeons, which, as we know, are blue 

 birds with the usual characteristic marks. We shall here- 

 after see that this subject possesses, independently of our 

 present object, considerable interest, so that I will give the 

 results of my own trials in full. I selected for experiment 

 races which, when pure, very seldom produce birds of a blue 

 colour, or have bars on their wings and tail. 



The Nun is white, with the head, tail, and primary wing- 

 feathers black; it is a breed which was established as long- 

 ago as the year 1600. I crossed a male Nun with a female 

 red common Tumbler, which latter variety generally breeds 

 true. Thus neither parent had a trace of blue in the plumage, 

 or of bars on the wing and tail. I should premise that 

 common Tumblers are rarely blue in England. From the 

 above cross I reared several young: one was red over the 

 whole back, but with the tail as blue as that of the rock- 

 pigeon ; the terminal bar, however, was absent, but the outer 

 feathers were edged with white : a second and third nearly 

 resembled the first, but the tail in both presented a trace of 

 the bar at the end: a fourth was brownish, and the wings 

 showed a trace of the double bar : a fifth was pale blue over 

 the whole breast, back, croup, and tail, but the neck and 

 primary wing-feathers were reddish; the wings presented 

 two distinct bars of a red colour ; the tail was not barred, but 

 the outer feathers were edged with white. I crossed this 

 last curiously coloured bird with a black mongrel of com- 

 plicated descent, namely, from a black Barb, a Spot, and 

 26 < Les Pigeons,' &c, p. 37. 



