Problems of genetics / by William Bateson.

  • Bateson, William, 1861-1926.
Date:
1913
Catalogue details

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

Credit: Problems of genetics / by William Bateson. Source: Wellcome Collection.

    155/290 (page 133)
    VARIATION AND LOCALITY 133 the United States northward to the limit of trees—a slightly diversified region of at least ten times the area of California—has only one! But when one comes to ask how the various forms are adaptational, and how the influences of environment have led to their production, only conjectures of a preliminary and tentative character could be expected in reply. Desert forms are no doubt pallid as in so many instances, and forest forms are more fully coloured, and we may readily enough accept such facts as indications of a connection between bodily features and the conditions of life, but further than that no one can go; so that when we find size, length of ears or of tail, the number of dorsal stripes, the pattern of the colours, not to speak of differences in the pigments themselves, all exhibiting large modifications, we cannot refer these peculiarities to the causation of environmental difference, save as a simple expression of faith. I incline far more to agree with Gulick who, after years of study of the local variations of the Achatinellidae, came to the conclusion that it was useless to expect that such local differentiation can be referred to adaptation in any sense.Even the most convinced Selectionist must hesitate before such facts as those related by A. G. Mayer regarding the distribution of Partula otaheitana, one of these Achatinellidae. The island of Tahiti has been scored by erosion so that a series of separated valleys radiate to the coast. From four successive valleys Mayer collected the species, and found that in the first (Tipaerui) valley all the shells were dextral (115, containing 73 young); in the second valley (Fautaua) 54 per cent, of adults and 55.5 per cent, of the young contained were sinistral; in the third valley (Hamuta) 69 per cent, of adults and 73 per cent, of young contained in them were sinistral; and lastly, in the fourth valley (Pirae) all the shells (131, containing 62 young) were sinistral.In connection with these observations I may mention the fact that in a certain pond in the North of England^® the sinistral form of Limnaea 1' J. T. Gulick, Evolution, Racial and Habitudinal, Carnegie Institution, Pub¬ lication No. 25, 1905. 18 A. G. Mayer, Mem. Mus. Сотр. Anal. Harvard, Vol. XXVI, 1902, p. 117. From the tables given I cannot ascertain the actual numbers from the two inter¬ mediate valleys, but they were considerable. To which I was very kindly guided by Mr. C. T. Trechmaim.