VI 11 PREFACE. 



an examiner has shown me are difficult to grasp and are com- 

 monly misunderstood ; and I have treated such subjects as are 

 useful in the practice of medicine or surgery, more fully than 

 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 

 believe it to be absolutely necessary that their first physiologi- 

 cal book should contain some account of the structure and 

 relationships of the organs, the functions of which they are 

 about to study. I have therefore added a short account of the 

 construction of the various parts discussed in each chapter; it 

 has, however, been found necessary to curtail this anatomical 

 portion to a mere introductory sketch. Numerous illustrations, 

 with full descriptions attached to each, are introduced to sup- 

 plement 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 physiologi- 

 cal 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 1 have 

 come to the conclusion that great scientific nicety and a scho- 

 lastic style of expression have a deterrent effect upon the be- 

 ginner's industry ; and I think it better that he should acquire 

 the first principles of the science in homely language, than pick 

 up technical 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 



