Heredity / by J. Arthur Thomson.

  • Thomson, J. Arthur (John Arthur), 1861-1933.
Date:
1908
Catalogue details

Licence: In copyright

Credit: Heredity / by J. Arthur Thomson. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    and germ-cells has not gone far. For if the leaf of a plant, or a quarter of a zoophyte, or an eighth of a sea-anemone, may grow into an entire organism with reproductive cells, we must infer that the characteristic heritable material, usually segregated in the reproductive cells, is diffusely present in the cells of the body in these organisms. Or else we must infer, as some have done, that there is no characteristic heritable material. The feature common to the ordinary forms of asexual multi- plication is, that the reproduction is independent of eggs or sperms, or of any process comparable to fertilisation. What starts the new life, and forms in this case the material basis of inheritance, is a Hberated portion of the parent. The heredity- relation is one of obvious material continuity. As regards inheritance, the feature characteristic of asexual multiplication is that the resemblance between parent and offspring tends to be complete. As Sedgwick (1899) expresses it: The offspring do not merely present resemblances to the parent—they are identical with it; and this fact does not appear to be astonishing when we consider the real nature of the process. Asexual reproduction consists in the separation of a portion of