128 PATHOLOGY 



Insufficient Air. A sufficient supply of fresh air is 

 necessary to the proper oxygenation of the blood and the 

 maintenance of health. 



Asphyxia. If the insufficiency be great, asphyxia, 

 a condition of cyanosis, depression, and stupor occur. 



Suffocation. Complete lack of air causes suffocation 

 and death. ' * 



Poisons. Definition. Any substance which intro- 

 duced into the living organism direct tends to destroy 

 the life or impair the health of that organism. 



The effects of poisons depend upon the nature of the 

 poison, the dose, and the nature of the individual. 

 Tolerance or immunity may be produced by repeated 

 ingestion of poisons. 



Corrosive Poisons, Escharotics, Caustics. Such poi- 

 sons, which are exemplified by various acids, alkalis, 

 mineral poisons, nitrate of silver, etc., cause destruction 

 of the cells with which they come in contact by abstrac- 

 tion of water and coagulation of the albuminous con- 

 tents of the cell. They cause local lesions similar to 

 burns, with necrosis, sloughing, and surrounding inflam- 

 mation. 



Organic poisons are those which enter the blood and 

 cause extensive lesions to various organs of the body, 

 as the kidneys, liver, gastro-intestinal mucous mem- 

 brane, heart muscles, blood-vessels, etc. Such poisons 

 are lead, arsenic, phosphorus, and mercury. 



Toxins of Bacteria. As we have seen, the toxins of 



