Address to the Anthropological Section of the British Association / by Sir William Turner.

  • Turner, Wm. (William), Sir, 1832-1916.
Date:
[1889]
Catalogue details

Licence: Public Domain Mark

Credit: Address to the Anthropological Section of the British Association / by Sir William Turner. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    suggestive pa])ers on Kinship and Heredity.' In the latter of these papers he developed the idea that • the sum total of the germs, geminuies, or whatever they may be called,' which are to be found in the newly fertilised ovum, constitute a stirp, or root. That the germs which make up the stirp consist of two groups—the one which develops into the bodily structure of the individual, and which consti- tutes, therefore, the personal structure; the other, which remains latent in the individual, and forms, as it were, an undeveloped residuum. That it is from these latent or residual germs that the sexual elements intended for producing the next generation are derived, and that these germs exercise a predominance in matters of heredity. Further, that the cells which make up the personal structure of the body of the individual exercise only in a very faint degree any influence on the reproductive cells, so that any modifications acquired by the individual are barely, if at all, inherited by the offspring. Subsequent to the publication of Mr. Gal ton's essays, valuable contributions to the subject of Heredity have been made by Professors Brooks, Jaeger, Naegeli, Nussbaum, Weismann, and others. Professor Weismann's theory of Heredity em- bodies the same fundamental idea as that propounded by Mr. Galton; but as he has employed in its elucidation a phraseology which is more in harmony with that generally used by biologists, it has had more immediate attention given to it. As Weismann's essays have, during the present year, been translated for aud published by the Clarendon Press,^ under the editorial superintendence of Messrs. Poulton, Schonland, aud Shipley, they are now readily accessible to all English readers. Weismann asks the fundamental question, ' How is it that a single cell of the body can contain within itself all the hereditary tendencies of the whole organ- ism?' He at once discards the theory of pangenesis, and states that in his belief the germ-cell, so far as its essential and characteristic substance is concerned, is not derived at all from the body of the individual in which it is produced, but du'ectly from the pareut germ-cell from which the individual has also arisen. He calls his theoiy the continuity of the yerm-plnsm, aud he bases it upon the supposi- tion that in each individual a portion of the specific germ-plasm derived from the germ-cell of the pareut is not used up in the construction of the body of that indi- vidual, but is reserved unchanged for the formation of the germ-cells of the succeed- ing generation. Thus, like Mr. Galton, he recognises that in the stirp or germ there are two classes of cells destined for entirely distinct purposes: the one for the development of the soma or body of the individual, which class he calls the somatic cells; the other for the perpetuation of the species, i.e. for reproduction. In further exposition of his theoi-y Weismann goes on to say, as the pro- cess of fertilisation is attended by a conj ugatiou of the nuclei of the reproductive cells—the pronuclei referred to in an earlier part of this address—that the nuclear substance must be the sole bearer of hereditary tendencies. Each of the two imit- ing nuclei would contain the germ-plasm of one parent, and this germ-plasm also would contain that of the grandparents as well as that of all previous generations. To make these somewhat abstract propositions a little more clear, I have de- vised the following graphic mode of representation:— Let the capital letters A, B, 0, D, &c., express a series of successive generations. Suppose A to be the starting-point, and to represent the somatic or personal struc- ture of an individual; then a may stand for the reproductive cells, or germ-plasm, from which the offspring of A, viz. B, is produced. B, hke A, has both a personal structure and reproductive cells or germ-plasm, the latter of which is represented by the letters ab, which are intended to show that whilst belonging to B they have a line of continuity with A. 0 stands for an individual of the third genera- tion, in which the reproductive plasm is indicated by abc, to express that, though ' Proc. Roy. Soc. Land., 1872, and Joum. Anthrop. Inst., vol. \'., 1876. » Oxford, 1889.