130 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



have been recorded, it appears that patience alone is necessary Within recent 



times, as far as animals are concerned, the crossing of distinct species has done little or nothing in 

 the formation or modification of our races. It is not known whether the species of silk-moth 



which have been recently crossed in France will yield permanent races Some 



authors believe that crossing is the chief cause of variability — that is, of the appearance of 

 absolutely new characters. Some have gone so far as to look at it as the sole cause; but this 

 conclusion is disproved by some of the facts given in the chapter on bud-variation. The belief 

 that characters not present in either parent or in their ancestors frequently originate from 

 crossing is doubtful." 



I thiiik that these quotations express the essentials of what we know about the results 

 of hybridization. Darwin is quite decided in his opinion that it is very difHcult to get 

 anything in the hybrid which is not in the parent. 



I have already stated that the hybrids which have hitherto been obtained in the case of 

 pigeons are mainly those between the male common ]3igeon and the ring-dove. No one, so 

 far as I know, has ever succeeded in getting the reciprocal hybrid ; that is, the hybrid be- 

 tween the male ring-dove and tlie female of any of the common races. It is comparatively 

 easy to mate a male common pigeon with the female ring-dove. The ring-dove is a quite 

 small species (the reader may refer to pi. 8). A male homer, such as I now have mated 

 with a ring-dove, would not from preference select a female of the ring-dove species, but 

 the isolation of such a pair is usually all that is necessary to bring about the mating. In this 

 case the male is much the stronger and the female makes no resistance; being much the 

 weaker she would not offer to peck or strike. But when the attempt is made to effect a 

 mating in the reverse order, using the small ring-dove as the male and set him to courting 

 the very large female homer, the male meets with difficulties at once. There is no natural 

 affinity between the two birds, and if the small male does not keep at a proper distance he 

 is likely to be punished at once. After he has received a few blows on his head the male 

 no longer wants to remain in the sight of such a large and offensive bird ; he becomes timid 

 and scarcely dares to approach her. Mating in this way, with a small male and a large 

 female, is something so contrary to the common rules of nature that it becomes difficult. 

 It is, however, not at all impossible when one takes it in hand and uses time and a few precau- 

 tions. It is a very simple process to isolate the two birds and put them where they can not see 

 their own species. At the time of mating pigeons do not know their own species unless it is 

 presented to them. Allowing that the male has a cage of apjjropriate size, he gets into the 

 habit of getting into the nest-box and calling for a mate. At that time the large female can 

 be caught in one's hands and held up alongside the nest-box. The male will be a little afraid, 

 but any blows with the beak or strokes with the wing can be prevented ; and if this be 

 repeated for a week or two, the male becomes accustomed to the sight of the large female and 

 at length welcomes her. When it is clear that the female is ready to mate she can perhaps be 

 trusted, especially if she shows any signs of fondling his head while being held in your hand; 

 she can then be set free in the cage, and if the male keeps on calling she will probably go 

 into the nest-box and the match is practically completed. But all this would not happen 

 in a state of nature. 



Of the difficulties of getting these hybrids I want to say just a word further. From one 

 pair beginning May 3, 1896, and ending August 23, 1897, I had 41 eggs and raised only 4 

 males; only 7 birds hatched; only 14 were fertilized. You can not get enormous numbers 

 of hybrids from the ring-dove and the common pigeon. I have kept a fantail mated with a 

 ring for more than a year and got only 1 bird. This was a white male with 13 feathers in 

 his tail ; the father's influence gave one additional feather to the tail of the young. A homer 

 mated for 6 months with a ring-dove supplied but 2 specimens, both males. Only a year 

 ago I succeeded in getting a male alba-risoria hybrid mated with a female homer (C. tab- 

 ellaria). The mating was accomplished some time in April (1897), and I got eggs shortly 



