Essays in scientific synthesis / by Eugenio Rignano.

  • Eugenio Rignano
Date:
[1918]
Catalogue details

Licence: In copyright

Credit: Essays in scientific synthesis / by Eugenio Rignano. Source: Wellcome Collection.

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    or morphological changes, corroborate the hypothesis that the latter changes, just like the movements, depend on the disturbances of the nervous circulation provoked by particular discharges of this energy. At the same time a whole series of facts revealing the most intimate co-operation of the ontogenetic and the physiological functional stimulus, and therefore the contingent substitution of one for the other (as happens, for instance, in the latest stages of the development of the eye), are in favour of the identity of their nature and in favour of the idea that the former is, in short, nothing but a reproduction, by internal causes, of the latter, this being provokable only by external factors. The centro-epigenetic hypothesis, finally, reconciles in one harmonious whole the very numerous and appar¬ ently contradictory facts which have made biologists propound the three famous and more or less inter¬ dependent dilemmas, of nuclear somatization or non¬ somatization, of the existence or non-existence of preformist germs, of the epigenetic or preformist nature of development. Thus, as far as the first of these three dilemmas is concerned, experiments on the isolation and on the displacement of blastomeres, on the formation of double monsters from a single egg, or of a single embryo from the fusion of two blastulas, on the reformation of com¬ plete organisms from fragments of hydra and fragments of Begonia leaves, all appeared to be in favour of non¬ somatization or nuclear non-specialization. On the other hand, the opponents of nuclear non¬ somatization mainly insist, apart from other less impor¬ tant arguments, on this : that the nucleus is the part,
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