Breeding and the Mendelian discovery / by A.D. Darbishire ... with illustrations in colour and black-and-white.

  • Darbishire, A. D. (Arthur Dukinfield), 1879-1915.
Date:
1911
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Breeding and the Mendelian discovery / by A.D. Darbishire ... with illustrations in colour and black-and-white. Source: Wellcome Collection.

    19/370 (page 3)
    BREEDING AND HEREDITY 3 created or destroyed. The primary object of cross¬ ing is to combine within one strain two desirable qualities existing in distinct strains. But an appar¬ ent result of crossing is very often a much more rapid production of something new than is brought about by selection {see Plate II.). The novelty in such a case, however, is an illusion, and due to the recombina¬ tion of characters which have been long hidden and long separated. Selection, then, creates something new ; crossing merely recombines characters which already exist. Very little—it may almost be said that nothing—is known of the causes which determine the origin of new characters, either in the domes¬ ticated state or in a state of nature. At any rate, there is not enough known to base a scientific prac¬ tice of breeding upon. But the art of breeding by the recombination of already existing characters— and it is a question whether in its ultimate analysis this may not be all that the breeder can do—^has been brought to a point of extreme precision by the dis¬ covery made by Mendel in 1865. And the object of this book is to make perfectly clear what that discovery was, and how it afíects the practice of breeding. The manner of origin of new forms will be dealt with because a knowledge of Prof, de Vries' observations on this process is necessary to an appre¬ ciation of the significance of Mendel's discovery. Ever since 1859, when Darwin effected the general acceptance of the doctrine of evolution, it has been believed that new forms have originated by the accumulation of the almost imperceptible differ-