326 THE BIOLOGICAL SCIENCES AND MEDICINE. [LECT. 



and is, such a thing as a pure science of medicine 

 a "pathology" which has no more necessary sub- 

 servience to practical ends than has zoology or 

 botany. 



The logical connection between this purely scientific 

 doctrine of disease, or pathology, and ordinary biology, 

 is easily traced. Living matter is characterised by its 

 innate tendency to exhibit a definite series of the 

 morphological and physiological phenomena which 

 constitute organisation and life. Given a certain 

 range of conditions, and these phenomena remain 

 the same, within narrow limits, for each kind of 

 living thing. They furnish the normal and typical 

 character of the species, and, as such, they are the 

 subject-matter of ordinary biology. 



Outside the range of these conditions, the normal 

 course of the cycle of vital phenomena is disturbed ; 

 abnormal structure makes its appearance, or the pro- 

 per character and mutual adjustment of the functions 

 cease to be preserved. The extent and the importance 

 of these deviations from the typical life may vary in- 

 definitely. They may have no noticeable influence on 

 the general well-being of the economy, or they may 

 favour it. On the other hand, they may be of such a 

 nature as to impede the activities of the organism, or 

 even to involve its destruction. 



In the first case, these perturbations are ranged 

 under the wide and somewhat vague category of 

 " variations ; " in the second, they are called lesions, 

 states of poisoning, or diseases ; and, as morbid states, 

 they lie within the province of pathology. No sharp 



