The microscopic anatomy of the teeth / by J. Howard Mummery.

  • John Howard Mummery
Date:
1919
Catalogue details

Licence: In copyright

Credit: The microscopic anatomy of the teeth / by J. Howard Mummery. Source: Wellcome Collection.

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    throughout the organic world, and as Professor Huxley says : 4 The primordial germs of a man, a dog, a bird, a fish, a beetle, a snail, and a polype, are in no essential structural respects distinguishable. In this broad sense it may with truth be said that all living animals, and all those dead faunae which geology reveals, are bound together by an all- pervading unity of organization.' Especially since Darwin’s time, the study of the cell and its relations to heredity has greatly occupied the attention of naturalists, and 1 microscopic anatomy has shown us the nature of the material on which organic evolution has operated ’. We have to distinguish between the 4 somatic ’ or body cells and the 4 germ ’ cells. The somatic cells build up the body of the individual, the germ cells are the racial cells, and the phenomena of heredity depend on their continuance from one generation to another. The germ cell, according to Weismann, is immortal ; the somatic cell perishes with the individual body. As Wilson says (9): 4 The cell theory must be placed beside the evolution theory as one of the foundation stones of modern biology—these two great generalizations have been developed along widely different lines of research, and have only within a very recent period met upon a common ground.’ The cell nucleus is shown to be the vehicle of inheritance, and, as this author further states, 4 thus the wonderful truth became manifest that a single cell may contain within its microscopic compass the sum total of the heritage of the species. The death of the individual involves no breach of continuity in the series of cell divisions by which the life of the race flows onwards—the individual body dies, it is true, but the germ cells live on, carrying with them, as it were, the traditions of the race from which they have sprung, and handing them on to their descendants ; —the body is merely the carrier of the germ cells which are held in trust for coming generations.’ Another question which has led to much controversy is whether characters acquired during the lifetime of the individual are capable of being transmitted to the offspring. This much-debated theorv was formulated by Lamarck in
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