In Situ Treatment of Contaminated Sediments

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 edition. Excerpt: ...experiments on butterflies appear to give bona-fide examples of hereditary transmission of characters, acquired under the influence of the environment. A perfect example of a purely local influence affecting the offspring is proved by the many and accurate observations made by Hyattj in the larval shells of certain cephalopods. Kropotkin and other Russian scientists think the struggle against environment is much fiercer than any intraspecific struggle, constituting a stronger obstacle to reproduction than competition among individuals. There is probably much to be said for the contrary, that it is favourable conditions, and a relatively easy life, which create and preserve new variations. Certain biologists have been led to the conclusion that evolution is going on in definite directions. This is what is called the orthogenetic view, which holds that the main factor in the transformation of species is a definite evolutionary direction which disregards usefulness completely. It is thus radically opposed to the Weismannian doctrine of natural selection. Rather, stress is laid on the effects of external influences, such as climate, or nutrition, on the constitution of a given organism which reacts in its own peculiar way. De Vries Theory of Mutation is winning increasing recognition. It involves the hypothesis of periodical, but sudden and quite noticeable, steps in evolution; and all conditions previous to mutation are held to be of far higher importance than all those subsequent to it. Two important phenomena stand out and mark the evolution of the organic world: one is the actual existence of different species, their differentiation in groups, the increasing complexity of organisms, their evolution from the lowest to...