PREFACE. Vll 



prepare themselves in a manner consistent with the modes of thought 

 that must prevail in the times now quickly approaching. It may be too 

 much for us to expect that our contemporaries, who have been educated 

 in the ideas of the past, should unlearn so much of what they have learn- 

 ed, should in so many things begin their studies again ; but we may de- 

 mand a right preparation from those who are only now commencing. 

 In offering to them this book, I do not present an untried work. It is 

 the result of an experience in teaching for many years, an attempt to set 

 forth in plain language the great features of the science, and to give in 

 sufficient detail a representation of the present state of Physiology. For 

 the purpose of facilitating its study, I have divided the whole subject 

 into two branches, Statical and Dynamical. The expediency of this has 

 been impressed upon my attention by the necessity of conforming the 

 course of lectures of which these pages are an abstract, to the wants of 

 a medical class. The physician is chiefly concerned with the conditions 

 of life the organic functions, as digestion, respiration, secretion, etc. 

 The doctrines of development and the career of an organic form are of 

 less pressing interest ; but it was very soon found that other advantages 

 were derived from this subdivision, as might have been expected from its 

 conformity to the usages of writers on other branches of Physical Science. 



To the general reader I may remark that I have endeavored to carry 

 put in the following pages the spirit of what is contained in the preced- 

 ing paragraphs. I have devoted more than twenty years not merely to 

 the study, but also to the experimental determination of physiological 

 questions, of which only a summary could here be offered. It was not 

 possible to give my own results more in detail in a formal text-book on 

 the entire science, but it may not perhaps be improper here to say that 

 opinions sometimes delivered in a few lines have cost me many days, or 

 even weeks, of expensive and laborious experiment. 



Among the contemporary works I have used as authorities are Dr. 

 Carpenter's different treatises, Todd and Bowman's Physiological Anat- 

 omy, and Kirke's and Paget's Hand-book. As respects monographs, the 

 language of the authors themselves has been employed wherever it was 

 possible. A list of wood-cuts is annexed, in which reference is given to 

 the sources from which those not original have been derived. In the 

 explanation of these engravings the description used is that of the au- 

 thors themselves in most cases, and it is incorporated in the text, as, 

 for instance, in Book I., Chapter XVII., in which, the engravings being 

 derived from the Neurology of Leveille and Hirschfield, the accompany- 

 ing descriptions are merely translations from the French ; or, again, in 

 Book II., Chapter VII. , in Dr. Prichard's statements of the methods ot 

 examining the skull. With respect to the original engravings, it will be 

 seen that many have been obtained by the aid of microscopic photog- 



