jSz 



THE BOOK OF POULTRY. 



toed progeny will be increased ; but still (sup- 

 posing, as we have done, no appreciable Dorking 

 blood in the farmyard), not so very many ; and 

 the four-toed progeny will still have little 

 tendency to produce five toes. But from these 

 five-toed chickens again select a pair to breed 

 together ; we shall now find the tendency much 

 increased ; probably half the progeny might be 

 five-toed, and even the four-toed ones would 

 produce more or less five-toed chickens. In the 

 next generation the tendency would be so 

 increased that probably very few four-toed 

 chickens would occur ; and in a generation or 

 two more a four-toed bird would be as rare as 

 the five-toed one originally was. We have 



accumulated into one direction the 

 A Strain. transmissive tendencies of many 



successive generations, and we have 

 now a strain, a race which we can depend upon 

 with almost absolute certainty to produce birds 

 with five toes. 



Now suppose, we will not say the first hen 

 herself, but even our first pair of birds from her, 

 with five toes, to be still alive after six years, as 

 might easily be the case, we might probably 

 select from our last progeny a pair that as 

 nearly as possible resembled them both in that 

 and other points : we might be unable to see 

 any difference at all between them as to the 

 point in question. But their breeding value 

 would differ enormously. The first pair have 

 no tendency to be relied upon to any extent ; 

 the last pair can be depended upon as regards 

 nearly every chick. The first gives us nothing 

 beyond individual features, on which we were 

 able, by care and system, to build a " strain " ; 

 the other pair represents work done, a point 

 fixed, the " strain," which only requires ordinary 

 care to preserve its character. 



Breeding for one point only is thus an abso- 

 lutely simple matter ; but every fowl is bred for 

 many points, which must be combined. Here 



the difficulty begins, and the novice 

 The usually finds that as he attempts to 



Breeder's deal with any one of those points 

 Difficulty which need improvement, he is apt 



to lose in some other already 

 attained. The reason for this is of course the 

 fact that the faults as well as the good points in 

 a parent tend to be reproduced ; and it is 

 impossible to say when the tendency to revert 

 to any past fault apparently overcome is prac- 

 tically lost ; absolutely lost it never is, and the 

 fault may crop up again on any provocation, 

 after even twenty generations of absence. And 

 the novice in breeding is almost constantly 

 offering such provocation towards the reappear- 

 ance of apparently banished faults. As each 



defect becomes distinctly apparent to him, he is 

 apt to select or buy a bird to correct it. Every 

 time he does this some influence really is 

 exerted, and if this were followed up the 

 ground gained might be secured. But little is 

 done towaxAs fixing the point by only one step ; 

 while the following season some other point 

 probably appears to need correction, and he goes 

 off after that And so he goes on, apparently 

 getting little farther at the best, and too often 

 confronted by the unexpected appearance of 

 new faults which fill him with as much amaze- 

 ment as despair. 



The greatest service Mr. Darwin ever con- 

 ferred upon breeders was to account for these 

 unexpected reappearances of long-banished 

 defects, and to explain the kind of 

 Effects of " provocation," as we have termed 

 Crossing. it, that recalled them into being. 



He clearly showed, by a large 

 amount of evidence, that the mere fact of cross- 

 ing between two entirely alien families has a 

 peculiar tendency of itself to produce reversion 

 to such long-lost characters. Thus it is that 

 when two different breeds of poultry are crossed, 

 there is always more or less production of that 

 black-red plumage which it is believed was the 

 colour of the wild jungle race of fowls ; or, when 

 two non-sitting breeds are crossed, there is often 

 a considerable recurrence in the progeny of the 

 long-lost instinct of incubation. In less degree, 

 but still in a very great degree, the same applies 

 to unrelated families of the same breed, which 

 have tendencies to different defects, or even 

 which have gone through a different course oj 

 breeding (as illustrated presently) in regard to 

 the points bred for. We knew a case in which 

 the mating with first-rate Spanish hens of a 

 cockerel of the finest quality from another 

 strain, produced an amount of red in face 

 sufficient to make a genuine Spanish fancier 

 tear his hair. This and many similar occur- 

 rences Mr. Darwin has made perfectly clear, 

 upon the simple principle that the mere act of 

 crossing — the mere fact that it is a cross in the 

 strain at all — has a strong tendency to cause 

 the reappearance of long-lost characters, which 

 will generally of course be bad ones from the 

 breeder's point of view, and this in great degree 

 independent of the individual merits of the 

 birds crossed. 



Successful breeding, therefore, such as builds 

 up a real "strain," or maintains a high standard 

 of excellence already attained, will consist 

 mainly of two factors. We must study on 

 the one hand such a course of selection as will 

 work steadily towards the desired end, with- 

 out frittering away the ground gained by 



