THE PRINCIPLES OF BREEDING 

 THREMMATOLOGY 



INTRODUCTION 



The main title of the present volume was chosen because self- 

 explanatory, though it less accurately expresses the scope of the 

 subject than does the sub-title, which is only beginning to come 

 into general use. 



Thremmatology, from the Greek thremma, a thing bred, is a 

 term proposed by Ray Lancaster 1 to cover the principles and 

 practices concerned in the improvement of domesticated animals 

 and plants. 



The term is broader than the " principles of breeding " because 

 it includes development as well as reproduction. It is distinct 

 from evolution in general, which attempts to explain the princi- 

 ples and forces connected with the origin and development of all 

 forms of life but without the slightest reference to economic 

 considerations. In evolution a protozoon is as important as a 

 pig, a hydra of as much significance as a horse, and the most 

 pestiferous weed as much an object of interest as either corn 

 or wheat. 



Thremmatology limits itself to those species and varieties whose 

 natural qualities made them useful to man in the beginning, and 

 it asks and seeks to answer this one question, How can they be 

 made still more useful and better adapted to the purposes of an 

 advancing civilization ? In this study forms of life that are of no 

 economic value are of no special concern except as their consider- 

 ation may throw light upon domesticated forms. This latter is 

 often the case, for it is doubtless true that the same principles 

 apply to all species, economic or otherwise, because none were 



1 'See Encyclopedia Britannica, ninth edition, XXIV, 841. 



