RESPIRATION 127 



whether in virtue of defective oxygen pressure or of the presence 

 of poisonous proportions of CO. In the first place it is evident that 

 a man may advance for some distance into such an atmosphere 

 before he begins to be seriously affected; for the temporary 

 marked increase in the breathing may, when the oxygen pressure 

 is defective, at first prevent an appreciable fall in the alveolar 

 oxygen pressure. This must, for instance, happen while a balloon 

 or aeroplane is rising rapidly, or while a miner is advancing with 

 an electric lamp into an atmosphere very highly charged with 

 fire-damp. When the breathing begins to quiet down again the 

 effects of the atmosphere will develop fully and it may then be too 

 late to turn. At 320 mm., for instance, I was at first quite capable 

 of making observations and taking notes, including a note of the 

 increased breathing and its subsequent quieting down. 



Another, and often still more serious, danger arises from the 

 gradual and insensible failure of judgment. A man suffering from 

 anoxaemia will usually go on, and insist in going on, with what 

 he set out to do. An airman will very probably continue to ascend, 

 oblivious to danger ; and a miner engaged in rescue or exploration 

 work, or in dealing with an underground fire, will insist in going 

 on when he is suffering from the anoxaemia of CO poisoning, 

 and will often fight any one who tries to make him desist. 



All these considerations apply equally to clinical cases of anox- 

 aemia ; and for this reason the condition is quite commonly never 

 recognized till too late. The early recognition of clinical anox- 

 aemia is a matter of great importance. 



Besides the immediate symptoms of anoxaemia there are a 

 number of delayed symptoms or after effects. They depend partly 

 on the length, and partly on the severity, of the exposure. A 

 short exposure, even with loss of consciousness, produces no 

 serious after symptoms ; but occasionally a man's behavior is very 

 abnormal for a few minutes after recovery. One of my ac- 

 quaintances has twice knocked persons down on waking up from 

 a short loss of consciousness caused by anoxaemia; and my own 

 behavior was distinctly abnormal just after coming out from the 

 steel chamber in the experiment alluded to above. Similar ab- 

 normalities after slight CO poisoning have often come under my 

 observation. Thus a well-known inspector of mines, on returning 

 to the surface after he had been affected by CO from an under- 

 ground fire, first shook hands very cordially with all the by- 



