Excerpt from The Inorganic Constituents of Marine Invertebrates Although many analyses of corals and molluscan shells are on record, some important groups of organisms have received only slight attention, and little has been done heretofore toward determimng the composition of their tests or skeletons. The few published data, more over, have been generally but not always incomplete in certain particulars, especially with regard to the localities from which the specimens analyzed were obtained, the depth of water in which each creature lived, and the temperature of its habitat. Even in our own work some of these details are lacking, but their great significance when known is strikingly evident in the study of such groups of animals as the echinoderms and alcyonarians. Furthermore, some of the older analyses are unsatisfactory for other reasons, for many of them were made to determine single facts, such, for instance, as the proportion of magnesium carbonate alone; and in others such essential constituents as organic matter were not taken into account, an omission that is especially serious, for it renders the accurate comparison of the analyses with others impossible. In the shells of mollusks the proportion of organic matter is small, but in the echinoderms, alcyonarians, and phosphatic brachiopods it is relatively large, ranging from 10 to even 40 per cent or more. This statement, however, must not be misconstrued; it refers, of course, only to the specimens, dried or alcoholic, which were actually analyzed. In order to compare the analyses, therefore, so as to determine the true composition of the inorganic shells or skeletons, the very variable amounts of organic matter must be rejected, and the remainders recalculated to 100 per cent. Relations then appear which are not recognizable when the crude unreduced analyses are compared. Any one of our tables Of analyses will Show this fact very clearly. In a strict sense completeness can not be claimed even for our analyses. Minor constituents which have been detected in marine organisms, such as barium, strontium, fluorine, manganese, copper, zinc, and lead, have been ignored. They occur, as a general rule, only in traces and have little or no significance with respect to the larger problems before us. What organisms tend to form limestones and what ones are notably magnesian, phosphatic, or siliceous are the ques tions which we are attempting to answer. In most of the analyses lime, magnesia, phosphoric oxide, sulphur trioxide, silica, and loss on ignition were determined. Alumina and oxide of iron were also considered and weighed together. The loss on ignition covered carbon dioxide. 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.