Vlll PREFACE. 



those which are essential only to abstract physiological knowl- 

 edge. 



As medical students are generally obliged to commence the 

 study of Physiology without any anatomical knowledge, I be- 

 lieve it to be absolutely necessary that their first physiological 

 book should contain some account of the structure and relation- 

 ships of the organs, the functions of which they are about to 

 study. I have therefore added a short account of the construc- 

 tion of the various parts discussed in each chapter; it has, 

 however, been found necessary to curtail this anatomical por- 

 tion to a mere introductory sketch. Numerous illustrations, with 

 full descriptions attached to each, are introduced to supplement 

 the explanation given in the text. 



So far as is consistent with an accurate treatment of the sub- 

 ject, I have avoided technical terms and scientific modes of 

 expression. I know that in attempting to explain physiological 

 truths in every-day language and in a plain, common-sense 

 way, I run the risk of appearing to lack the precision that such 

 a subject demands ; but after mature consideration I have come 

 to the conclusion that great scientific nicety and a scholastic 

 style of expression have a deterrent effect upon the beginner's 

 industry ; and I think it better that he should acquire the first 

 principles of the science in homely language, than pick up tech- 

 nical odds and ends in learned terms, the meaning of which he 

 does not comprehend. 



As many words, strange to the first year's student, have to be 

 used and must be learned, it has been thought advisable to add 

 a short glossary, containing an explanation of the most ordinary 

 physiological expressions. 



Great difficulty is always found in fixing upon a starting- 

 point at which to begin the study of Physiology. To begin 



