Report Of The Scientific Results Of The Voyage Of H M S Challenger Vol 19

Author : C. Wyville Thomson
Publisher : Forgotten Books
ISBN 13 : 9781330374856
Total Pages : 222 pages
Book Rating : 4.3/5 (748 download)

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Download or read book Report of the Scientific Results of the Voyage of H. M. S. Challenger, Vol. 19 written by C. Wyville Thomson and published by Forgotten Books. This book was released on 2015-06-25 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excerpt from Report of the Scientific Results of the Voyage of H. M. S. Challenger, Vol. 19: During the Years 1873-76, Under the Command of Captain George S. Nares, R. N., F. R. S. And the Late Captain Frank Tourle Thomson, R. N Hardly any traces of coloration were visible, no external appendages distinguished the different species, no definite shape, marked out by hard portions of the integument, which facilitate the recognition of representatives of so many other divisions of the animal kingdom, were anywhere noticeable. The majority of the specimens in the collection were cylindrical or flattened fragments, generally truncated, and rarely so intact that it was possible at first sight to distinguish between head and tail. The cephalic slits of those specimens which belong to the group of the Schizonemertea, and the mouths of many of the fragments, were the only external marks that could serve both for the discernment of what was posterior and anterior, and for a rough and provisional arrangement of the forms as they were probably related to each other. The various figures on Pl. I. will give a general impression of the appearance of the fragments just alluded to. I more especially insist upon the poor aspect presented by the preserved material of the Nemertea in order to impress the reader with the fallacy of pronouncing an unfavourable judgment on a collection of marine invertebrates by relying merely upon the external appearance of the specimens. For I can hardly sufficiently emphasise the exceedingly good state of preservation of the large majority of the Challenger Nemertea. They were, indeed, in so perfect a state that the internal anatomy of all the fragments could be determined, and in very many cases delicate histological details could be revealed with as much facility as if the specimens had been captured a few days instead of ten years ago. I feel the more called upon to make this statement, and to express my admiration for the extreme care which the scientific staff have so evidently given even to unattractive and small-sized fragments, as it has been occasionally stated (even in certain of these Reports) that the Challenger material was sometimes unfit for the minute investigation of internal anatomical structures. So far as the collection of Nemertea is concerned, this statement is absolutely unfounded. The study of the fragments and complete worms constituting this collection was only possible by aid of the microtome. This instrument was very freely made use of, and the most important improvement to which it has been subjected by Caldwell, whose automatic microtome was available, has enabled me to go into many more details than would otherwise have been possible. The total number of sections through different specimens of the Challenger material which have been prepared in the drawing up of this Report amounts to 19,560. They were all of them stained with Ranvier's picrocarmine. As already mentioned in the Narrative of the Voyage, the number of Stations from which the Challenger obtained Nemertea is more than twenty. 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.