Haynes: Inbreeding in Dogs 



369 



Average dogs. Champions. 

 SCOTTISH TERRIERS 



Inbred 3 1- 



Line-bred 4 9 



Out-bred 93 90 



AIREDALE TERRIERS 



Inbred 7 2 



Line-bred 6 10 



Out-bred 87 88 



Note. — The "Line-bred" in the above only includes dogs bred from the primary cross of half 

 brother to half sister, and there are certainly dogs in the "Out-bred" that are truly in-bred. 



inbred dogs winning championships nine from half brother and sister with 



furnishes a gauge to judge the effective- the same sire and one from half brother 



ness of this breeding system in ac- and sister with the same dam. 



complishing the result desired by the It will be immediately noted in the 



breeders of these animals. above table that in- and line-breeding 



Of 100 Scottish terrier champions, are more common in Airedales than in 



one is inbred, from a dog mated to his Scottish terriers, the ratio being close 



own daughter. Of 100 Airedale cham- to two to one in all cases. Possibly this 



pions, two are inbred, one from a bitch may be accounted for by the fact that 



mated to her own son and one from full being a manufactured variety, close 



brother and sister. breeding has been more or less forced 



because of lack of breeding stock. It 



LINE breeding. ^-^^ ^^^^ ^^ ^^^^^ ^j^^^ ^^^ ^^^^^ ^^^^^_ 



In the case of line-breeding, however, ing popularly supposed to be practiced 



we get very different figures. Taking by dog fanciers is not apparent. In the 



only the two primary crosses of line- cases of the average dogs, only 7% of the 



breeding, i. e., the crossing of half Scottish terriers and 14% of the Aire- 



brother and sister, sired by the same dales are closely bred, 



dog, and half brother and sister, dammed The salient feattu-e of these figures 



by the same bitch, which, of coiu-se, for the breeder is, of course, the evidence 



does not begin to include all line-bred they present that line-breeding has, in 



dogs, we find that of the hundred the cases of these two breeds at least, 



Scottish terriers picked at random proved very much more effective than 



four are line-bred, all from half brother in-breeding in accomplishing the object 



and sister with the same sire. Of the desired. The ratios of champions pro- 



htuidred average Airedales six are line- duced in Scottish terriers is 1 to 9, and 



bred, five from half brother and sister in Airedales, 1 to 5. These figures con- 



with the same sire, and one from half firm my studies in prepotency in Aire- 



brother and sister with the same dam. dales. ^ 



Among the hundred Scottish terrier Summarizing the data, it is evident 

 champions nine were bred this way, that neither inbreeding nor close line- 

 eight from half brother and sister with breeding is used as much by dog breeders 

 the same sire and one from half brother as is generally supposed, and that of the 

 and sister with the same dam; and 10 two systems line-breeding has been the 

 Airedales champions were so bred, more productive of results. 



'Science, N. S. XXXVII, No. 977, pp. 404-405. 



Mendelism in Man 



Such rules (those of Mendelian heredity) have been demonstrated in operation 

 for an immense diversity of characteristics in both animals and plants in great 

 variety. It should be explicitly stated, however, that in the case of the ordinary 

 attributes of normal men we have as yet unimpeachable evidence of the manifes- 

 tation of this system of descent for one set of characters only, namely the color 

 of the eyes. — William Bateson: Biological Fact and the Structure of Society (1912). 



