Journal of Morphology, Vol. 23

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Excerpt from Journal of Morphology, Vol. 23: 1912 1. The study of heredity in embryos offers in one respect a wider field than that in adults inasmuch as heterogeneous hybrids rarely reach the adult stage. Eight years ago I found a method by which the eggs of the sea-urchin can be fertilized by the sperm of starfish, ophiurians and holothurians. The larvae are purely maternal, namely plutei. The results were confirmed by Godlewski for the fertilization of the egg of the sea-urchin by the sperm of the crinoid. It is well known that if we cross two homogeneous forms, e.g., two forms of sea-urchins, the paternal influence can be clearly seen in the pluteus stage. Since I have never published the figures of my experiments on heterogeneous hybridization, I may supplement my former statements with a few drawings. Figs.1 to 6 are camera drawings of plutei of Strongylocentrotus purpuratus produced by artificial parthenogenesis. The plutei are, of course, in every detail identical with the plutei obtained if these eggs be fertilized with sperm of their own species. Figs. 7 to 9 are drawings of five days old plutei of Strongylocentrotus purpuratus and Strongylocentrotus franciscanus. They differ from the pure breeds of S. purpuratus in several characters of the skeleton which exist in the pluteus of franciscanus but are absent from purpuratus, namely the greater roughness of the skeleton, the presence of cross bars and the greater length of the arms. In figs. 10 to 13 are shown the five days old plutei of the egg of S. purpuratus fertilized with the sperm of the starfish (Asterias). About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.