Comparative Anatomy And Physiology
Cód:
491_9781443732222
Originally published in 1885. PREFACE: THE reader who is sufficiently acquainted with the progress in vertebrate physiology during the last phase of physiological methods, and who knows how scattered and incomplete are the investigations which have been made by the same kind of physical and chemical inquiries on invertebrate animals, will not expect to find in the present volume any complete statement of the physiology of animals, in the sense in which that term is now used. Such observations as have been made without especial reference to the vital processes of man are, for the most part, very valuable and suggestive but the time to write a text- book of Comparative Physiology, aswe now understand it, has not yet arrived. All that I have attempted to do in this little book has been to illustrate the details of structure by a notice of such experimental inquiries as I have con- vinced myself, or have adequate reason to believe, are, in their broad outlines, correctly stated. I have much more attempted to make use of what were long since called the experiments that Nature makes for us, by referring to, sometimes perhaps insisting on, the dif- ferent methods by which similar results are attained by different animals. That which I have most constantly kept before myself, and which I hope the student will faithfully bear in mind, is, that there has been an evolution of organs as well as of animals, and that he who desires to understand the most complicated organs must first know the structure of such as are more simply constituted. In pursuit of this object, I have written about organs rather than about groups of animals but I have added an index in which the various parts of an animal are collected under the head of its name so that the student who desires to use this manual as a zoological text-book will have no difficulty in selecting the portions of the chapters which bear on a particular form or set of forms. I have departed a little from the ordinary method of wr
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