Heredity / by J. Arthur Thomson.
- Thomson, J. Arthur (John Arthur), Sir, 1861-1933.
- Date:
- 1908
Licence: In copyright
Credit: Heredity / by J. Arthur Thomson. Source: Wellcome Collection.
Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.
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![it not the expression of a predetermined inheritance in a more or less predetermined environment ? DelBnitions of Heredity.—It may be of interest to give a few samples of definitions : The word ' Heritage ' has a more limited meaning than ' Nature,' or the sum of inborn qualities. Heritage is confined to that which is inherited, while Nature also includes those individual variations that are due to other causes than heredity, and which act before birth.—Francis Galton, Natural Inheritance, 1898, p. 293. Heredity is the law which accounts for the change of type between parent and offspring, i.e. the progression from the racial towards the parental type.—Karl Pearson, The Grammar of Science, 1900, p. 474. Under heredity we understand the transference to the offspring of qualities of the parent or parents.—T. H. Montgomery, Jr., Proc. American Phil. Soc. xhii. 1904, p. 5. [But the line of descent is from germ-cell to germ-cell. The parent is the custodian or trustee of the germ-cells rather than their producer. It is too metaphorical to speak of the parent transferring qualities to the offspring. The hereditary relation includes the occurrence of variations' as well as the reproduction of likenesses. And what are the offspring apart from their inheritance ?] ' Heredity ' is most usually defined by biologists as referring generally to all phenomena covered by the aphorism ' like begets like.' In this sense it denotes, inter alia, the phenomenon of the constancy of specific or racial types and of sexual characters ; a character may be said to be inherited when it always, in one genera- tion after another, is one of the characters of the species, of the race, or of the one sex of the race, as distinct from the other. The species, race, or sex, so to speak, ' begets its like ' as a whole. But then a further question remains ; even if the type of the race is constant, do individual types within the race beget their like ? In so far as any individual diverges in character from the mean of the race, do his offspring tend to diverge in the same direction, or not ? It is to this question that statisticians have confined them- selves, and they speak of a character being ' inherited ' or not according as the answer to the question is yes or no—they deal solely with what we may term ' individual heredity.' —G. Udney Yule, T902, p. 196. [Bigistsolo are as much concerned with individual](https://iiif.wellcomecollection.org/image/b2129589x_0035.jp2/full/800%2C/0/default.jpg)
