Principles of breeding : a treatise on thremmatology or the principles and practices involved in the economic improvement of domesticated animals and plants / by E. Davenport.

  • Davenport, E. (Eugene), 1856-1941.
Date:
[1907], ©1907
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Principles of breeding : a treatise on thremmatology or the principles and practices involved in the economic improvement of domesticated animals and plants / by E. Davenport. Source: Wellcome Collection.

    19/750 (page 3)
    would constitute no exception to the rule that a man must real ize the fruit of his own labors and in his own generation, for breeding is a business and must be made to pay. The breeder must therefore work faster than nature, and thremmatology can not make use of a leisurely operating evolutionary principle unless its action can be accelerated or its cumulative effects exaggerated. Yet again, man cannot afford the immense numbers and the whole sale destruction that characterize nature’s methods of working changes. Animals and even plants cost money, and a relatively large proportion must meet the conditions, or the enterprise must be abandoned. Business considerations therefore set arduous limitations upon thremmatology in respect to both time and numbers from which evolution in general is entirely free. The breeding business has its own particular problems, some of the most important of which unfortunately the known facts of evolution are least able to answer. The profitable study of this subject will, however, be assisted by a clear statement of these problems. The problems of the breeder. Certain questions stand clearly out in the minds of practical breeders, and though an attempt to answer them seriatim would not be the best method of study, and though some of them cannot be answered with certainty in the present state of knowledge, yet nothing is of more con sequence at the outset than that the student get a clear idea of the problems needing solution and towards whose solution the study of thremmatology is directed. They are substantially as follows : To what extent are the characteristics of an individual at matur ity due to its ancestry (heredity), and to what extent are they due to the conditions of life (environment), such as food, climate, exercise, and general care during development ? Are the influences of the conditions of life limited to the indi vidual or are they in certain instances and to some extent carried over upon the offspring ? that is, are the effects of environment inherited ? Can variations be directly controlled to any extent whatever, or only indirectly through selection and by special care during development ?