LONDON WILLIAM HEINEMANN 1896 [ All rights reserved ]...

Shortly after the appearance of Dr. Oscar Hertwig's treatise 'Präformation oder Epigenese?' I published in Natural Science (1894) a detailed abstract of it. But the momentous issues involved in the problem of heredity, and the great interest excited by Dr. Weismann's theories, make it desirable that a full translation should appear. By the kindness of Dr. Hertwig and his German publisher, this is now possible. I have prefixed an introduction, written for those who are interested in the general p

Inquiry into the problems of heredity is beset with many difficulties, of which not the least is the temptation to argue about the possible, or the probable, rather than to keep in the lines of observation. Setting out from a laborious and beautiful series of investigations into the anatomy of the Hydromedusæ, Weismann came to think that the organic material from which the sexual cells of these animals arose was not the common protoplasm of their tissues, but a peculiar plasm, distinct in its na

What is development? Does it imply preformation or epigenesis? This perplexing question of biology has reappeared recently as a problem of the day. Of late years there have been set forth contradictory doctrines, each seeking to explain the process by which the fertilised egg-cell, an apparently simple beginning, gives rise to the adult organism, which often is exceedingly complicated, and which has the capacity of producing new beginnings like that from which it itself arose. The opposing views

As may be seen in his essays, On Life and Death , On the Duration of Life , etc., Weismann believes himself to have established a fundamental distinction between unicellular and multicellular organisms. Unicellular organisms (he would have it) do not undergo natural death, but, since they are able to reproduce themselves continuously by a process of simple division, are immortal. Multicellular organisms, on the other hand, must perish after a definite duration of life, and so are mortal. He make

Now that criticism of the germplasm theory has given us a bias in the right direction, it is necessary to map out more clearly the path along which solution of the problem may be sought. In general terms, our problem is the necessary origin from an egg, always of the same organism, with its manifold characters, and the explanation must avoid the attribution to the egg of characters foreign to its nature as a cell. This is the more necessary as Weismann objects to the supposition that cell-divisi

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