i88 



Rctvogressive Processes. 



The loss of volume of the cells in atrophic conditions consists in 

 part in decrease of their so-called paraplastic substances, partly in 

 loss of their actively functionating constituents (Ribbert). The 

 former, including the stored-up nutrient matter (fat, glycogen) and 

 the cellular secretory products (mucin), are generally used up 

 without chance of replacement from the blood supply or from the 

 protoplasm ; the above-mentioned diminution of size of the liver 

 cells, for example, resulting, or of fat cells which after loss of their 





Fig-. 21. 



Fattv infiltration of tlie sural muscles in pseudoliypertropliic musouhir atropliy ; 



X 220. (After Tlioma.j 



fat are found shrunken into simple connective tissue spindle cells. 

 The functional substance, as the contractile substance of muscle 

 cells, undergoes metabolic alterations resulting in diminution of 

 its bulk. It is difficult to make out how intercellular substances 

 come to undergo the observed solution and removal, as it cannot 

 be here assumed that it is simply carried off by the lymph, the 

 appearance of giant cells indicating clearly that the processes opera- 

 tive are of complicated nature. In the bone marrow the presence 

 and increase of these elements seem to be related with the removal 



