cxii THE BEGINNINGS OF LIFE. 



or non-ascertainable. They are no longer regarded as enti- 

 ties. They are due to changes of state in some portion of 

 the body, whereby the vital movement in the part is diverted 

 from a normal into an abnormal mode of activity. 



The complicated structure of the human body, and the 

 allocation of specific functions to specific parts, necessitates, 

 and has occasioned, a functional correlation and interde- 

 pendence. Any disturbance of this normal balance of func- 

 tions of necessity entails a definite sequence of pathological 

 states and actions, A morbid change in an important organ, 

 if it interferes with the function of the part, rarely exists 

 alone. It sets up other associated effects, whereby the dis- 

 turbed equilibrium of functions is more or less replaced by 

 a new adjustment 



The effects are often well marked, though very variable, 

 when the disease is one in which any notable alteration in 

 the composition of the blood occurs. Supplying the mate- 

 rials of growth for all parts of the body, any changes in the 

 composition of the blood are found, now to affect one organ 

 and now another most profoundly. Before entering, how- 

 ever, upon the consideration of those diseases in which 

 changes in the nature and quality of the blood form the 

 most important condition of the disease, it will be useful to 

 dwell for a time upon some of the more local pathological 

 changes that occur in the more solid tissues of the body. 

 The two sets of phenomena are closely related to one an- 

 other. Morbid states which are at first purely local may, 

 after a time, produce general diseases; and a general or 

 constitutional disease frequently entails limited lesions in 

 special parts. A wound or a local inflammatory process 

 may lead to thrombosis, gangrene, and blood-poisoning ; 

 just as, following a reverse order, various febrile conditions 

 may cause local lesions now in one organ and now in an- 

 other. 



