Kraemer: Effects of Inbreeding 



231 



they regained both weight and spirit. 

 If the evils of inbreeding are over- 

 emphasized here, Ballance, the success- 

 ful breeder of Malays, stands on another 

 platform. Inbreeding does not neces- 

 sarily involve the deterioration of the 

 stock, he believes; "but all depends on 

 how this is managed. My plan has 

 been to keep about five or six distinct 

 runs, and to rear about 200 or 300 

 chickens each year, and to select the 

 best birds from each run for crossing. 

 I thus secure sufficient crossing to pre- 

 vent deterioration." 



"With pigeons," says Darwin in con- 

 clusion, "breeders are unanimous that 

 it is absolutely indispensable, notwith- 

 standing the trouble and expense thus 

 caused, occasionally to cross their 

 much-prized birds with individuals of 

 another strain, but belonging, of course, 

 to the same variety. It deserves notice 

 that, when size is one of the desired 

 characters, as with pouters, the evil 

 effects of close interbreeding are much 

 sooner perceived than when small birds, 

 such as short-faced tumblers, are valued. 

 The extreme delicacy of the high fancy 

 breeds, such as the tumblers and im- 

 proved English carriers, is remarkable; 

 they are liable to miany diseases, and 

 often die in the egg, or during the first 

 moult; and their eggs have generally to 

 be hatched under foster-mothers. 



"Although these highly prized birds 

 have invariably been subjected to much 

 close interbreeding, yet their extreme 

 delicacy of constitution can not perhaps 

 be thus fully explained. Mr. Yarrell 

 informed me that Sir J. Sebright con- 

 tinued closely interbreeding some owl- 

 pigeons, until from their extreme steril- 

 ity he as nearly as possible lost the whole 

 family. Mr. Brent tried to raise a breed 

 of trumpeters, by crossing a common 

 pigeon, and recrossing the daughter, 

 granddaughter, great-granddaughter 

 and great-great-granddaughter with the 

 same male trumpeter, until he obtained 

 a bird with 15-16th of trumpeter's blood ; 

 but then the experiment failed; for 

 'breeding so close stopped reproduction". 

 The experienced Noumeister also asserts 

 that the offspring from dove-cotes and 



various other breeds are 'generally very 

 fertile and hardy birds'; so again, MM. 

 Boitard and Corbie, after 45 years' 

 experience, recommend persons to cross 

 their breeds for amusement; for, if they 

 fail to make interesting birds, they will 

 succeed under an economical point of 

 view, 'as it is found that mongrels are 

 more fertile than pigeons of a pure race.'" 



CONCLUSIONS WARRANTED. 



I have here gone back to literal quota- 

 tions from Darwin, because the views 

 of this great naturalist, who was also 

 an expert breeder, so exactly coincide 

 with the general experience of practical 

 men. I will freely admit that some of 

 the evidence given in his examples is of 

 damage done by inbreeding, and some 

 of it merely of the results of pairing two 

 animals which are not of first-class 

 strength ; the effects of bringing together 

 two strains of weakness are thus mis- 

 taken for the effects of inbreeding. But 

 if one admits that famous breeders 

 thoroughly understand the necessity of 

 breeding only from sound animals, then 

 it must be admitted that these numerous 

 examples prove that continued inbreed- 

 ing in itself is injurious. As far as the 

 practical production of farm animals 

 goes, inbreeding does not offer itself as 

 a desirable method; but this, however, 

 is well understood. I might easily quote 

 a great number of further instances from 

 Darwin, which lead one to want to use 

 caution in the practice of inbreeding. 

 At the same time, however, I must say 

 that in England the question has been 

 illuminated just as it has for us, and it 

 is absolutely wrong to believe, as we 

 are so often told, that the English un- 

 conditionally advocate and practice 

 inbreeding in their herds. 



Things went the same way in France. 

 If we examine Sanson, Baron, Magne, 

 Cornevin and other important writers 

 on the question of inbreeding, we find 

 that here again views are decidedly 

 diverse. Sanson- fully recognizes the 

 potency of inbreeding, and the right 

 places for its application, without suffi- 

 ciently defining the different grades of 

 close interbreeding. Baron takes a 



^Sanson, Traite de Zootechnie, Paris, 1896. 



