16 THE ACTION OF THE LIVING CELL 



hours, and the muscles, upon stimulation, will con- 

 tract. Indeed, the major part of our knowledge of 

 neuro-muscular physiology is based upon experi- 

 ments made upon the surviving organs of "dead" ani- 

 mals. Eventually, of course, such isolated tissues will 

 die, owing to starvation or other change from the 

 environment in which they normally find themselves 

 in the intact animal. 



One must, therefore, distinguish between the death 

 of the organism and the death of the individual com- 

 ponents, the tissue cells of the organism. From a prac- 

 tical standpoint, the former is simply a loss of the 

 nicely balanced and integrated activities of the indi- 

 vidual tissue cells, while the latter is an actual death 

 which may result from the former. 



On the other hand, as has been noted above, if the 

 tissue cells are transplanted to a suitable environment, 

 such as that employed in the technique of tissue cul- 

 ture, there is no reason to believe that they should not 

 live forever. 



The localized death of tissue cells — i.e., necrosis — 

 may therefore be brought about in either of two 

 fashions: by a localized injury — for example, the 

 application of a caustic chemical or a destructive 

 physical agent such as X-radiation; or by a change 

 in the internal environment induced by the disfunc- 

 tioning of some remote tissue or organ, such as that 

 of the kidney, previously mentioned. This being the 

 case, it is logical to assume that because of the recipro- 

 cal relations existing between the component tissues 

 of an animal, a localized injury must inevitably result 

 in induced changes, or perhaps even the death of other 



