Excerpt from On the Embryology of Echinoderms, Vol. 9 The yolk contracts somewhat immediately after the fecundation takes place, and we might repeat here, word for word, the description of the changes which the yolk und goes in the Starfishes, and have the history of the changes during the segmentation of the yolk of an Echinus. For an account of this I would refer the reader to the fifth volume of the Contributions to the Natural History of the United States, by Professor Agassiz. The embryo, on escaping from the egg, resembles a Starfish embryo, and it would greatly puzzle any one to perceive any difference between them. The forma tion of the stomach, of the asophagus, the intestine, and the water-tubes takes place in exactly the same manner as in the Starfish, the time only at which these different organs are differentiated not being the same. We have thus very early in the history of these two orders differences which to a practised eye tell at once to which of them the young larva belongs. What is a particularly important difference is the forma tion in Ophiurans and in Echinoids of calcareous rods at an early period of the larval condition. 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.