

PEEFACE TO THE THIRD EDITION. 





IN preparing the first edition of this work, published about five years 

 ago, I hoped that my experience as a practical physiologist and public 

 teacher and the discipline of eleven years during which I was occupied in 

 writing my large treatise in five volumes might enable me to make a book 

 which would meet the wants of practitioners and students of medicine. 

 My expectations in this regard have been more than fulfilled. My work 

 has been very favorably received by the profession ; it is extensively used 

 as a text-book, and two very large impressions of the first edition and a 

 second edition, published in 1879, have been exhausted. Encouraged by 

 the favorable reception of the book, I have spared no pains in its revision 

 for a third edition. I have rewritten certain portions, carefully corrected 

 all the errors and inaccuracies that I have been able to discover, and have 

 eliminated here and there statements that did not seem to me to be fully 

 in accord with the existing state of physiological knowledge. In addition 

 to minor corrections, I have made the following important alterations : I 

 have adopted the views of Bowman, lately confirmed by the experiments 

 of Heidenhain and others, with regard to the functions of the Malpighian 

 bodies of the kidney. The section upon Animal Heat has been entirely 

 rewritten ; and I have given an account of my new experiments upon this 

 subject, published in 18 79, showing the probable generation of heat in 

 the body by the union of oxygen and hydrogen and the formation of water. 

 I have introduced a short description of the cerebral convolutions, with 

 a new diagram, and a brief account of the recent discovery by Boll, of 

 " retinal red." I have also added a diagram illustrating the mechanism of 

 micturition, and a figure, kindly prepared for me by Dr. E. G. Loring, 

 of New York, showing the appearance of the fundus of the eye as seen 

 with the ophthalmoscope. 



Although the work may appear to some readers to be rather formidable 

 in size, I have endeavored to condense it as much as possible. It undoubt- 

 edly contains much more than is usually taught in lectures to medical stu- 

 dents ; but, in a text-book for the use of practitioners as well as students, it 

 is not desirable, in my opinion, to omit any subject properly belonging to 

 human physiology. I venture to hope that those who use this work as a 

 book of reference will find nearly all subjects in which they may be inter- 

 ested more or less fully discussed, although I have generally omitted foot- 

 notes referring to other authorities. My main object, however, has been to 

 meet the requirements of medical students. 



NEW YORK, April, 1880. 



