Outlines Of General Zoology PDF Download

Excerpt from Outlines of General Zoology: Mammals, Birds, Reptiles, Fishes, Invertebrates Zoology is a systematic exposition of animals according to their external and internal structure, and the functions of their organs. The internal structure can be frequently inferred from the external characters we may, for example, determine the aliment of an animal, and the structure of the digestive organs, by examining the teeth. This is, however, not sufficient in all cases, so that it becomes necessary also to examine the internal parts, because the relation between animals depends upon the entire organization; and this being well ascertained, the functions of the various organs can generally be determined without much difficulty. From the earliest period it was found necessary to group those animals together which were observed to have certain natural characters in common. We find, upon inquiry, that the endeavors to arrange animals systematically have taken two principal directions, which have been named natural and arttficz'al classification. The former has in view the classification of animals upon the greater or less perfection of the various organs, among which those connected with the circulation and oxygenation of the blood, locomotion, and digestion, hold a prominent place; the latter depends upon a character or habit arbitrarily chosen, and independent of others. A character, however, which may be regarded as unessential by one observer, will be considered as of the greatest importance by another. In the earlier stages of science, when the number of known species was comparatively small, artificial methods were popular, because they were considered easy of acquisition: now, however, it is found that they are calculated to give superficial ideas and that to present the condition of zoological science in its true light, a more philosophical system must be made use of. 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.