SHOCK 15 



That connective tissue cells from the chick heart may 

 be kept alive in the laboratory for years exceeding 

 the normal life span of the fowl, and presumably, if 

 the tissue culturist so desires, for an indefinite period, 

 was shown conclusively by Carrel and Ebeling. Nat- 

 ural death, it thus appears, is restricted to multicel- 

 lular organisms. 



During the evolution of such organisms, the cells of 

 the various tissues have become dependent upon their 

 neighbors for such necessities of life as food and oxy- 

 gen. For example, if the blood-flow to an individual 

 organ is interrupted, the cells of that organ die, owing 

 to starvation and want of oxygen, while other tissues 

 continue to live unless the death of the first organ in 

 some fashion deprives the other tissues of their normal 

 environment. If, for example, the cells of the glomeru- 

 lus of the kidney are damaged, as in nephritis, the loss 

 of proteins from the blood causes water to diffuse more 

 easily into the other tissues of the body, which thus 

 become waterlogged. 



Coincidentally the elimination of nitrogenous waste 

 products is impaired and the body cells suffer from 

 their accumulation. In the brain, the accumulation 

 of such waste products results in coma and eventually 

 in the death of the organism. In similar fashion, the 

 injury or death of any of the component tissues of a 

 multicellular organism will result in disturbances and 

 perhaps the death of other tissues in the body. 



When an animal is decapitated, death ensues; yet 

 for some time after the decapitation the individual 

 tissues may be shown to be alive. The heart, if re- 

 moved to a suitable environment and supplied with 

 the necessary salts, will continue to beat for some 



