Societies and Academies

Abstract

LONDON. Royal Society, Nov. 3.—Hans Spemann (Croonian Lecture): Orgfisers in animal development. The conception of ‘organisers in dcveopment’ has been derived from experiments in amphibian embryos in the earliest stages. The different regions of such an embryo have not the same value for development; most of them are relatively indifferent and do not carry their destiny in themselves. This can be shown by transplantation of these parts into other regions of the embryo; they follow the development of their new environments. But there is a certain region in the embryo, parts of which, when transplanted into, an indifferent region of th embryo, do not adapt themselves to their new environment, but retain their own character, and force, as it were, the others to follow them. Such parts organise a new embryo, which. is built up partly by the transplanted cells, partly by the cells of the host. Therefore they were called ‘organisers,’ and the region where they lie together in those early stages of development the ‘centre of organisation.’ Further experimeBts have been made to determine the extent of this centre, its origin, its intimate structure, and the nature of the organising influence.