United States or Falkland Islands ? Vote for the TOP Country of the Week !
The important law of inheritance at corresponding periods was also set aside. In no case, as Weismann points out, is the original mutilation of the nervous system ever transmitted. Even where an extirpated ganglion was never regenerated in the parent, the offspring always regained the part in an apparently perfect condition.
Caterpillars and butterflies often show us a further step in advance in the direction of minute imitation of ordinary surroundings. Dr. Weismann has published a very long and learned memoir, fraught with the best German erudition and prolixity, upon this highly interesting and obscure subject.
Weismann has emphasized this idea in his doctrine of "panmixia," or the withdrawal of selection, which always results in degeneration. Selection, artificial or natural, may serve to counteract this universal tendency of organic life, but only approximately. As Sir William Dawson says, "All things left to themselves tend to degenerate."
Opposing these Neo-Lamarckians were such prominent scientists as August Weismann, A.R. Wallace, E. Ray Lankester, who strenuously opposed the idea that "acquired characters," or more precisely parental experience, are ever transmissible.
When the processes of development and of reproduction are closely scrutinized, we find evidence which, together with the conclusions based thereon, was first effectively stated by August Weismann, of Freiburg, in his famous little book, "The Germ-Plasm."
LAFARGUE, La théorie darwinienne. I am well aware that in these last years, perhaps in consequence of the relations between Darwinism and socialism, consideration has again been given to the objections to the theory of Darwin, made by Voegeli, and more recently by Weismann, on the hereditary transmissibility of acquired characters. See SPENCER, The Inadequacy of Natural Selection, Paris, 1894.
Nor is it consistent with itself: thus the boa-constrictor has rudiments of hind limbs and of a pelvis, and if it be said that these bones have been retained "to complete the scheme of nature," why, as Professor Weismann asks, have they not been retained by other snakes, which do not possess even a vestige of these same bones?
Granting that external influences of environment and bodily condition may effect the germ-cells; granting even that some of the most general effects of use and disuse might be transmitted, what warrant have we for believing that the special acquired characteristic can be transmitted? Weismann answers, None at all.
But this was only his ignorance; for man may deny his descent from an ape and be eligible as a churchwarden without being any the less a convinced Evolutionist. What is more, the religious folk can claim to be among the pioneers of Evolutionism. Weismann, Neo-Darwinist though he was, devoted a long passage in his History of Evolution to the Nature Philosophy of Lorenz Oken, published in 1809.
Romanes writes: "Professor Weismann has shown that there is throughout the metazoa a general correlation between the natural lifetime of individuals composing any given species, and the age at which they reach maturity or first become capable of procreation." This, I believe, has been the conclusion generally arrived at by biologists for some years past.
Word Of The Day