16 Farmers' Bulletin 1167. 



apart from the horns of cattle, coat color, eye color, and the like, 

 the application of this law to livestock breeding has a long way 

 to go before its principles are adaptable to practical use by breeders. 

 It is fairly certain, however, that many of the obscure happenings 

 in animal breeding are really manifestations of Mendelism. Most 

 cases of atavism ("throw backs" to a remote ancestor), for ex- 

 ample, are probably Mendelism in practice. 



The animal structure is so diverse and complicated that the de- 

 termination of the application of Mendel's law to the inheritance 

 of the characters which affect the commercial value of domestic 

 animals is a task of tremendous magnitude. Great progress has been 

 made in laying the foundations for the scientific study of animal 

 breeding by working out the principles of this law, and we may ex- 

 pect still greater progress in the future. Biologists who are studying 

 heredity have their faces set in the right direction. The accomplish- 



FIG. 9. Purebred Hereford sire, scrub dam, and offspring. Note how the character- 

 istic markings of the Hereford sire, especially the white face, are transmitted. 



ments of the last twenty years in the study of heredity have taken this 

 subject out of the field of guesswork, and for this service all animal 

 breeders are under obligations to Mendel and his disciples. 6 If, by 

 skillful selection and intelligent breeding methods we can get re- 

 sults of permanent value; if, with the present knowledge, we can 

 make real progress in animal breeding, we can afford to wait for 

 the more definite working out of Mendel's law, with the assurance 

 that this law controls the mechanics of heredity in domestic animals 

 and that any practical application of it to animal breeding will add 

 to our store of useful knowledge and to the efficiency of our breeding 

 methods. 



6 The discovery of this law by the Austrian monk, Gregor Mendel, in 1865, its virtual 

 disappearance for 35 years and its rediscovery simultaneously by several investigators 

 working independently, form one of the romances of science. Mendel's papers attracted 

 very little attention when published, owing, no doubt, to the intense interest of the 

 world in the researches of Darwin. Mendel died in 1884 without realizing the importance, 

 to humanity, of the work which he had done. 



