The Germ-plasm : a theory of heredity / by August Weismann ; translated by W. Newton Parker and Harriet Ronnfeldt.

  • Weismann, August, 1834-1914.
Date:
1893
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Licence: Public Domain Mark

Credit: The Germ-plasm : a theory of heredity / by August Weismann ; translated by W. Newton Parker and Harriet Ronnfeldt. 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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    with to construct a theory of heredity, though much was wanting to render it complete. In my last essay I certainly suggested the possibility of solving one of the most difficult problems in heredity—viz., the co-operation of the hereditary substance of the parents in sexual reproduction—by assuming the existence of these * ids'; but I did not for a moment suppose that in doing so I had propounded a complete and elaborated theory of heredity, as some of my readers have thought to be the case; much still remained to be done first. I had as yet not touched upon such phenomena of heredity as have no direct bearing on the question of sexual reproduction, and had also abstained from any mention of the fundamental point of my theory of heredity—namely, the co?istitution of the ids. Although I pointed out that they must possess a complex structure which undergoes gradual and regular changes during the development of the individual from the egg-cell, I did not enter into any further details. This question remained in abeyance, for I was by no means sure whether the conception that I had formed on a priori grounds of the minute structure of the ids would prove tenable when viewed in the light of all the many phenomena of heredity. No conclusion could be arrived at respecting the structure of the ids till these phenomena had been individually considered. All my investigations on the problem of heredity were so far only links, to be some day united into a chain which had as yet no existence. The question of the ultimate elements on which to base the theory was the very point on which I remained longest in doubt. The ' pangenesis ' of Darwm, as already mentioned, seemed to me to be far too mde- pendent of facts, and even now I am of the opinion that the