1921.] 



Research in Animal Brekdinc. 



11 



RESEARCH IN ANIMAL BREEDING. 



1. 



R. C. PU-NNETT, F.R.S., 



. Professor of Genetics, Uiuversitji of ('(unhrnlrie. 



When Mendel's discovery in heredity, made over 50 years ago, 

 was unearthed in 1900, it v^as at once cleai' to a few scientific 

 jnen that a new era in the breeding of animals and plants had 

 commenced. What the breeder requires is " certainty " in 

 so far as it is possible to attain it. When a given mating is 

 made he Welshes to know what is likely to result, and further, 

 as he is generally of an intelligent and inquiring mind, why the 

 result is obtained. 



Through jNIendel's work and its recent development the 

 breeder is at last .being placed in a sound position to answer 

 these questions. Plant breeders have not been slow to take 

 advantage of the new knowledge. Realizing early the 

 immensely greater powers of control over the living thing 

 conferred upon them by Mendel, they set to work to build up 

 new^ strains of cereals and other valuable plants. It is 

 unnecessary to detail here the remarkable success which has 

 already attended their efforts, nor to forecast the enormous 

 economic gain that must come to the world when the methods 

 are applied to the produce of vast tropical areas. The rapidity 

 with which plant breeding stations are springing up in both 

 hemispheres is evidence of the service which ^lendel rendered 

 to mankind. 



While, however, the plant breeder is now faii'ly embarked 

 upon bis career of conquest, the breeder of animals tends to 

 lag behind. Nor is this difficult to understand. The majority 

 of plants are self-fertilized. It is an easy matter to obtain the 

 j)nre strains essential for purposes of Mendelian analysis, to 

 keep them pure, and to purify any desirable new strain that 

 may be built up. Animals with their bi-sexual mode of repro- 

 duction are far more complicated things to deal with, and as we 

 shall see later, the separation of the sexes may in itself intro- 

 duce complications peculiar to this mode of reproduction. Then 

 again, plants are cheap owing to their great powers of multipli- 

 cation. Thousands of wheat plants may be grown for the cost 

 of a pig. This rapid multiplication of plants renders more easy 

 the process of Mendelian analysis, and in consequence, man's 

 power of control over them is enhanced. 



