PHYSIOLOGY IN THE STUDY OF DISEASE 85 



restlessness and the distress and later drowsiness ? 

 Why the quick pulse ? and why the congestion of 

 the veins ? Are these due to different causes or 

 to some common cause ? 



The work of Haldane and of others had shown 

 that the breathing is regulated by the condition 

 of the blood going to the base of the brain. If the 

 carbonic acid formed in the muscles and passed 

 from them into the blood increases above a certain 

 level, breathing is increased, and thus the carbonic 

 acid is got rid of. 



In the case of the gassed patient carbonic acid 

 cannot freely get away, and so it accumulates in 

 the blood and increases the breathing. It is a 

 beneficent response, for the increased breathing 

 helps to overcome the effect of the drowning out 

 of the lung, and not only favours the giving up of 

 carbonic acid, but at the same time helps to increase 

 the taking up of oxygen by the blood. 



What of the restlessness and distress and the 

 later drowsiness ? Physiological investigations have 

 shown that these are not the result of the increased 

 carbonic acid in the blood, but of a decrease in the 

 oxygen. 



It is this want of oxygen which is the real 

 danger. Life is simply a process of combustion for 

 which oxygen is as necessary as it is for a fire, and 

 a decreased supply of oxygen is incompatible with 

 life. 



