GENERAL PATHOLOGY. 29 



These two varieties are generally combined. 



Atrophy is accompanied by impaired function, which is 

 frequently still further impaired by its association with de- 

 generation of the tissue. 



Atrophy is local or general. 



Local atrophy may be due to — • 



1. Imperfect blood supply. 



2. Impaired nutritive activity. 



3. Excessive functional activity, leading to exhaustion. 



4. Inflammation. 



5. Nervous disturbance. 



General atrophy is usually simple, affecting firstly the 

 adipose tissue, then the muscles and viscera, and lastly the 

 tissues of the nervous system. 



It may be due to — 



1. Deficient supply of nutriment. 



2. Excessive waste ; as in exhausting diseases. 



3. Impairment of nutritive activity. 



DEGENERATIONS. 



Degeneration, unlike atrophy, is characterized by quali- 

 tative rather than by quantitative changes in the tissues 

 and organs. 



Two kinds of degeneration are distinguished. 



In the one the albuminoid constituents are directly meta- 

 morphosed into some new material of lower type ; whereas 

 in the other the new material is deposited in the tissues from 

 the blood. 



The first kind is termed Metamorphosis ; the second is 

 termed Infiltration. 



In both there is impaired function of the parts involved ; 

 but this is much more marked in the metamorphoses. 



