THE CAUSATIOX OF DISEASE. 1 9 



briefly allude to the processes of hypertrophy and degeneration. 

 The former is due to a modification of cell-E. Consider the case 

 of muscle. Increased exercise leads to a larger supply of blood, 

 the E of individual muscle-cells is thus richer in food-stuffs 

 and Oxygen, and the cells therefore grow to their fullest limit, 

 or may even be excited into multiplication. But what will 

 happen if, on the contrary, their blood-supply be cut off wholly, 

 or in part, while at the same time all agents of putrefaction 

 be excluded ? Degeneration occurs, fat taking the place of 

 protoplasm. Again, the influence of E upon cell-action is 

 well shown in . the case of those cells which congregate in 

 an inflamed area. If the blood-supply to them be deficient, as 

 it often is, they degenerate into fat, and perish, and may thus 

 (if circumstances do not permit of their removal) form cheesy 

 masses ; if, however, the E be compatible with life, they 

 continue to live and grow. There is every possible grade — 

 according to the nature of the E — between the extremes of 

 rapid and complete degeneration, on the one hand, and of 

 advanced and permanent development, on the other. 



Many unicellular organisms float freely in a fluid medium 

 from which they derive their food, and to which they return 

 their refuse. But the component cells of complex tissues are 

 fixed ; it becomes therefore necessary to provide for them a 

 fitting cell-environment, and to this end organs are required 

 for the manufacture of nutrient blood-plasma for securing 

 the proper supply of 0, for conveying the fluid food and to 

 the tissues, and lastly, for removing the refuse matters. If 

 any one of these systems is thrown out of gear, it is obvious 

 that the cell-environment will be interfered with. There will 

 cease to be that proper interaction of cell and cell-envi- 

 ronment which constitutes health. The interaction will be 

 abnormal. There will, in other words, be disease. 



All disease is ultimately such an improper interaction of 

 cells and their environment. We have therefore now to 

 inquire into the several ways and means by which this cell- 

 environment may be influenced j for disease — it is , obvious 

 from our definition of it — may come through any of them. 

 The following list exhibits some of the ways in which cell- 

 environments may be morbidly modified : — 



C 2 



