JUL 9 iaU8 



THE PRODUCTION AND FIXATION OF NEW BREEDS. 



By \V. E. Castle, Assistant Professor of Zoology, Harvard University, 



Cambridge, Mass. 



The art of animal breeding has been practiced by man since the 

 earliest dawn of civilization. In many cases its products attained 

 centuries ago a degree of excellence which we can scarcely hope to 

 surpass, as in the horses of Arabia and the poultry of China. Of 

 course, these and other breeds have since been modified in useful direc- 

 tions and are capable of further useful modifications; but for the 

 needs of the time and place where bred, the horses and the poultry of 

 centuries ago were probably not inferior to our own. In creating new 

 breeds of domesticated animals, we are merely adapting to new and 

 special conditions very ancient and excellent breeds. This is a work 

 of the highest importance, and I have no desire to minimize it. But 

 while we contemplate with satisfaction present attainments and pros- 

 pects, let us not forget our debt to the past for taking wild species 

 into domestication and moulding them to meet man's needs. To those 

 unchronicled pioneer breeders we owe entirely the material with which 

 we work. 



We stand at the beginning of a new era in which breeding will pass 

 from the condition of an art into that of a science. The difference will 

 be that we shall know the reasons for our procedure, whereas the 

 breeder of the past did not. We shall continue to produce breeds just 

 as he produced them, but we shall know how we produce them, a thing 

 of which he was largely ignorant. His work was largely haphazard ; 

 ours will be orderly. He experimented until he got what was wanted 

 or until he found his ideal unattainable ; we shall produce what we 

 want, and knowing what is attainable will not attempt the impossible. 

 He progressed indirectly, awaiting the caprice of chance; we shall go 

 straight to the goal, knowing the way beforehand. 



No finer swords, perhaps, were ever made than those which the 

 Saracens produced six centuries ago at Damascus and Toledo, but to 

 produce steel of the many varieties now in use, and in the quantities 

 required by the diversified industries of to-day would have been a task 

 beyond the powers of the Saracen either to accomplish or to imagine. 

 Scientific knowledge of metallurgy has brought about the change; no 

 less revolutionary does the application of scientific knowledge to the 

 art of animal breeding promise to be. 



The first great advance made toward such a knowledge was taken 

 by Gregor Mendel when he discovered the principle of unit characters 

 in heredity, the principle, namely, that the various physical and physi- 

 ological characteristics of individuals are transmitted in heredity as 

 distinct units. An individual is nothing but the sum total of these 

 unit characters, which it receives from its parents and hands on to 

 its children. The ordinary individual has two parents and, for each 

 unit character, it receives a contribution from either parent. When 



