Transcriber’s Notes: Underscores “_” before and after a word or phrase indicate _italics_ in the original text. Equal signs “=” before and after a word or phrase indicate =bold= in the original text. Small capitals have been converted to SOLID capitals. Illustrations have been moved so they do not break up paragraphs. Old or antiquated spellings have been preserved. Typographical errors have been silently corrected. THE BODY AT WORK [Illustration] [Illustration] [Illustration] [Illustration: FIG. 1.—PHOTOMICROGRAPHS OF CELLS OF THE CORTEX OF THE CEREBELLUM AND CEREBRUM. _For description see p._ x. _Frontispiece._] THE BODY AT WORK A TREATISE ON THE PRINCIPLES OF PHYSIOLOGY BY ALEX HILL, M.A., M.D., F.R.C.S. SOMETIME MASTER OF DOWNING COLLEGE, CAMBRIDGE WITH 46 ILLUSTRATIONS LONDON EDWARD ARNOLD 1908 [_All rights reserved_] PREFACE Few subjects are as well provided with text-books as physiology; yet it may be doubted whether the interests of the amateur of science have been adequately cared for. From his point of view there are certain obvious drawbacks to even the most admirable of text-books. Writing for medical students, their authors assume that their readers have passed through two years of preliminary training in physics, chemistry, and biology; they take for granted that they will have the privilege of supplementing their study of the theory of physiology with practical work in a laboratory; they treat all parts of the subject with equal thoroughness. In this book I have endeavoured to describe the phenomena of life, and the principal conclusions which have been drawn as to their interdependence and as to their causes, in language which will be understood by persons unacquainted with the sciences upon which physiology is based. I have omitted all reference to experimental methods and to the technique of the science, save when a knowledge of the means by which information has been obtained is essential to a comprehension of its bearing. I have passed over such sections of the subject as are generally considered unsuitable for ordinary discussion. And since this book neither aims at being an introduction to the systematic study of physiology, nor poses as an aid in the preparation for professional examinations, I have treated with some thoroughness the more recondite and the more suggestive results of recent research, and have tried to indicate the trend of modern thought regarding problems as yet unsolved. I have endeavoured to reflect the intrinsic interest of the science apart altogether from its medical applications.