2 INTRODUCTOEY. 



should understand Pathology, wliicli, iu its full and proper 

 meaning, implies a knowledge of diseased processes, abnormal 

 conditions, and morbid structures, as well as what precedes 

 them and what results from them. For this purpose a knowledge 

 of many collateral branches of science is essential, more parti- 

 cularly a knowledge of Physiology ; and no one can be a physio- 

 logist without being an anatomist and a chemist. By Physiology 

 is meant that science wdiich treats of the conditions, phenomena, 

 and laws of life whilst the animal body is in a state of health. 

 Without a knowledge of the laws of health, it is impossible to 

 grasp and comprehend the laws of disease, for it may be truly 

 said that the latter are but perversions of the former, and are 

 natural, or physiological, under the operation of existing circum- 

 stances and causes. 



In addition to Pathology and Pliysiology, Medicine compre- 

 hends THERArEUTics, or the science which explains the actions of 

 remedies upon the animal body, the means by which disease may 

 be naturally overcome, and a return to health assisted and pro- 

 moted; and Hygiene or Prophylaxis, which treats of the sanitary 

 condition, food, and surroundings whereby disease may be pre- 

 vented, and all other methods by wdiich health may be preserved. 



Disease may also be studied clinically : that is to say, disease 

 may be studied as it presents itself in each particular case to 

 the attention of the observer. The term clinic can scarcely, with 

 propriety, be applied to any method by which diseases of the 

 lower animals are studied, as it means "a patient who keeps his 

 bed," but for the want of a better, and as it is now a generic 

 term, I am constrained to retain it. 



Before proceeding further with our object, it is necessary 

 that I endeavour to give a definition of disease, and this I can 

 only do by following the rules already laid down by our latest 

 pathologists. A definition of disease can only be arrived at by 

 comparing it with the standard of health, and health, says 

 "Williams, " consists in a natural and proper condition and pro- 

 portion in the functions and structures of the several parts of 

 which the body is composed ; " but no fixed rule can be applied 

 to this, for what is health in one may be disease in another, and 

 there are degrees or gradations of health which cannot be said 

 to be due to disorder or disease. For example, one animal may 

 fatten and maintain the most robust health upon the same 



