PREFACE. 



A knowledge of the fundamentals of human physiology is 

 essential in the training of the dental student, because physiology 

 constitutes, along with anatomy, the basic science upon which 

 all medical and surgical knowledge is founded ; and dentistry is 

 a highly specialized department of surgical practice. To oper- 

 ate on the teeth without knowing something about the physi- 

 ology of the body as a whole, would reduce the dentist to the 

 level of a craftsman who, although perhaps very highly skilled 

 in his technical work, was yet quite ignorant of the nature of 

 the machine upon a part of which his work had to be done. 



But there are also practical reasons why the dentist should 

 be familiar with physiology, for good health, and not good looks 

 alone, depends very largely on sound teeth. The neglect of this 

 fact may cause disturbances in bodily functions to which, at 

 first sight, the teeth may apparently bear very little relation- 

 ship ; thus, extreme emaciation, with its consequent lowering of 

 the normal resistance of the body towards disease and infection, 

 is well-known to be frequently due to no other cause than some 

 abnormal or pathological condition affecting the teeth ; and, on 

 the other hand, this very condition itself may become intract- 

 able to the most skilled dental treatment and hygiene, if meas- 

 ures are not taken at the same time to improve the general health. 

 Although it is obviously beyond the province of the dentist to 

 undertake the treatment of these general conditions, yet it is 

 most important that he should be sufficiently familiar with the 

 normal functioning of the human body to be able to recognize 

 what is really at fault. A knowledge of the laws of nutrition 

 and dietetics must therefore form a most important part of every 

 course in dentistry, and these have received particular attention 

 in this book. 



The physiology of the digestive system, of the circulation of 

 the blood and of the nervous system is scarcely less important. 

 The pain and shock produced by a dental operation may cause 

 considerable disturbance in the action of the heart or in the dis- 

 tribution of blood in the body, and this disturbance, especially 



