82 THE ACTION OF THE LIVING CELL 



in the next chapter, the properties of cytost are quite 

 at variance with those of histamine. For the present, 

 the point we desire to stress is that in shock the in- 

 creased diffusion of fluid from the blood occurs sec- 

 ondarily to the congestion of the capillaries. 



With the increased permeability of the capillaries, 

 cytost present in the blood may be expected to diffuse 

 along with other blood constituents into the fluid 

 (lymph) bathing the tissue cells. This consideration 

 is of importance since, as will be shown subsequently, 

 cytost in sufficiently high concentration may exert a 

 distinctly deleterious action upon the various cells 

 with which it comes in contact. 



In the experiments so far considered, cytost has ap- 

 peared to act selectively upon the abdominal viscera 

 and lungs. As will be seen presently, however, this 

 selectivity of action is more apparent than real, for 

 other tissues, such as muscle and brain, are affected by 

 cytost. Such effects, nevertheless, become evident in 

 such tissues only when they are exposed to the direct 

 action of cytost in a concentration considerably greater 

 than is necessary to bring about similar changes in the 

 viscera. 



The extreme sensitivity of the viscera to such a 

 tissue toxin is perhaps analogous to the fact that among 

 humans, at any rate, these organs are the most sus- 

 ceptible to disease. Statistical studies of the causes 

 of death have shown that, in the great majority of 

 cases, death is actually due to various derangements 

 of these particular tissues. (Pearl, 1922.) 



This is perhaps not surprising, for these organs 

 really represent the actual metabolizing center of the 

 mammal. The skeletal tissues are merely a support- 



