OF PHYSIOLOGY; BEING AN ACCOUNT OF THE LAWS AND PRINCIPLES OF THE ANIMAL ECONOMY, ESPECIALLY IN REFERENCE TO THE CONSTITUTION OF MAN. BY THOMAS JOHNSTONE AITKIN, M.D., F.R.C.S.E. LECTURER ON PHYSIOLOGY AND ON MATERIA MEDICA; MEMBER OF THE MEDICO- "Shall the work say of him that made it, He made me not?" LONDON: PRINTED FOR SCOTT, WEBSTER, AND GEARY, 36 CHARTERHOUSE SQUARE. HARVARD COLLEGE LIBRARY FROM THE LIBRARY OF MRS. ELLEN HAVEN ROSS JUNE 28, 1938 EDINBURGH: PRINTED BY W. BURNESS. PREFACE. A KNOWLEDGE of the structure of the human body cannot but be considered by every cultivated, intelligent, and inquiring mind, as a most desirable acquisition. In tracing the many curious contrivances which are exhibited in its organization, in perceiving the admirable adaptation of its parts to the performance of their varied offices, and in viewing the whole series of its organs in their mutual relation and subserviency, one exercises the highest faculties of his mind, and acquires information that may be useful in life. Indeed, so obvious is the importance of an acquaintance with the mechanism of our bodily frame, that one, viewing the subject in a general sense, might naturally wonder why Anatomy and Physiology are not considered as indispensable elements of education. The object of the present work is to give such an account of the structure of the animal body, and especially of that of man, as well as of the manner in which the various parts of the machinery operate, as may be readily understood by those who may not previously have directed their attention to investigations of this kind. Science is enriched with several works of great merit on these subjects; but they either are exclusively intended to exhibit a minute and detailed description of the organization, in order to adapt them to the use of persons who, from their profession, necessarily require an intimate knowledge of the size, proportion, and relative situation of the different parts of the body; or else they treat of the functions in such a manner as can only be properly understood by those who have previously obtained considerable acquaintance with the structure. The descriptions, moreover, although sufficiently clear and explicit to those who are familiar with such subjects, are generally loaded with technicalities, and the allusions and illustrations, though readily understood and appreciated by the initiated, are but little adapted to interest or instruct the general inquirer. Nothing so much distinguishes the present age as the eager desire evinced by all classes of society for acquiring scientific knowledge: the crowds attending public lectures, the number and character of the works on various departments of science that daily issue from the press, and even the tone of general conversation, sufficiently shew how anxiously information of this kind is sought after. It has been from the conviction that a work like the present is needed, and not from any belief that I am especially qualified for the task, that I have been induced to undertake it. I have, however, endeavoured to the utmost of my power to fulfil the objects in view, to afford such a description of the various structures of the body as may serve to convey a correct idea of their organization, and to give such an account of their mode of action as appears best to accord with experience and observation. The professional reader will readily perceive that the descriptions are drawn directly from the objects described. Indeed, that I might do justice to the subject, this was the only method that was left me, in attempting to give to the general reader an account of the intricate construction of many parts of the animal machinery. It was impossible to refer to the various sources of information respecting the uses and applications of the different parts; since, though many of the discoverers of physiological truths be well known, appreciated, and justly venerated by the professional student, still their authority and names can have but little comparative interest or weight with those whose attention is less directed to such inquiries. Neither |