1921.] 



Research in Animal Breeding. 



Suggestive as the poultry experiments are, we recognise that 

 we are only at the beginning of this kind of enquiry. Some 

 experiments of a similar nature with rabbits gave a ditt'erent 

 result.* A cross was made between the Polish, which is the 

 smallest of the breeds of ujmesticated rabbits, and the Flemish, 

 which is one of the largest. The Polish was used as the father 

 of the Fl animals, which were intermediate, and fairly uniform 

 in size (Fig. 7). From two pairs of such Fl animals an F2 

 generation was raised. Owang to lack of : ccommod .t'on the 

 total number of offspring reared was only 37. Nevertheless this 

 F2 generation shows a remarkable feature in that the size of 

 the Fl animals was not exceeded, although some were nearly as 

 small as the Polish parent. The absence from the F2 generatic n 

 of anything approaching the size of the Flemish is highly 

 puzzling, and no explanation can at present bn offered. The 

 experiment is being repeated with the difference that the Fl 

 animals have been bred from Pohsh doe x Flemish buck, 

 instead of in the reverse wav as before. 



3^ 



sit. 



I r I I I M I I M I I I I I i I I ( M I f I I I I I I 1 1 1 I 1 I M I I I M I I I I I 1 I I i I I M n I I I I I I I i I I I I I ( I I I I I 



t'c?Po 



LLsh 



I 



I - 

 . Q- 



00 in 



Fig. 7. Illustrating the inheritance of weight in a Polish x Flemish cross. Each individual 

 epresented by a dot on the chart according to its weight in lb. and oz. Thus, ti e F, animal, 

 6 weighs 4 lb. 13 oz., and the PI 17 weighs 5 lb. 2 oz. 



When planning investigations on these cases of apparently 

 continuous variations it was felt desirable to choose another 

 example of a different type. Accordingly a " pattern " case 

 was selected in rabbits. Here, as in many of the domesticated 

 animals, we encounter white markings, and the extent of these 

 is very variable. We can in fact obtain a continuous series 



* *' Genetic Studies in Rabbits. 1. — On the Inheritance of Wei^^ht," by 

 R. C. Punnett and the late P. G. Bailev : Joimuil of Genetics. Vol. Vlli. 

 1918-19. 



