66 GENERAL BIOLOGY 



is so firmly associated with the external phenomena 

 just mentioned that its use in connection with the 

 oxidations and reductions taking place in tissues is 

 apt to be misleading. For this reason the term 

 Energesis has been proposed for tissue respiration. 

 Since the function of the process is to release the 

 necessary energy required in the life of the organism, 

 this word is very appropriate and deserves wider use. 



Poisons. So long as katabolism is compensated 

 by an approximately equal anabolism, the life process 

 proceeds normally. If the destruction of proto- 

 plasm, however, occurs too rapidly for the con- 

 structive changes to keep up with it, then abnormal 

 conditions arise which soon result in the death of 

 the tissue or of the organism. Thus, although 

 oxidations are absolutely essential for life, excessive 

 oxidation soon destroys the protoplasm, and certain 

 oxidizing substances, such as potassium perman- 

 ganate, are poisons on this account. Other sub- 

 stances, such as the salts of the heavy metals, 

 mercury, silver, etc., destroy the life of the proto- 

 plasm by entering into permanent combination with 

 substances composing it. Other more complex 

 substances act as poisons by substituting themselves 

 for essential parts of the protoplasm. Thus many of 

 the proteins elaborated by plants, such as strychnine, 

 morphine, caffeine, etc., are deadly poisons to the 

 tissues of higher animals. The actions of these 

 substances are, however, very diverse. Indeed, 

 the animal organism constantly forms such protein- 



