126 RESPIRATION 



held responsible for his actions. Without reason he may begin to 

 laugh, shout, sing, burst into tears, or become dangerously violent. 

 He is, however, always quite confident that he himself is perfectly 

 sane and reasonable, though he may notice, for instance, that he 

 cannot walk or write properly, cannot remember what has just 

 happened x and cannot properly interpret his visual impressions. 

 When unable even to stand, owing to experimental CO poisoning 

 or to anoxaemia produced by low pressures in a steel chamber, I 

 have always been quite confident in my own sanity, and it was 

 only afterwards that I realized that I could not have been in a 

 sane state of mind. 



A recent experience of this kind was in a steel chamber in which 

 Dr. Kellas, who is an experienced climber in the Himalayas and 

 has exceptional powers of resisting anoxaemia, was with me. 11 

 We had reduced the pressure to 320 mm., and as I could no longer 

 write or make any observations I handed him the notebook. He 

 afterwards told me that I remained sitting, but always answered 

 his questions quite deliberately and confidently, and insisted on 

 his keeping the pressure at 320 mm. This went on for an hour and 

 a quarter, of which time I could afterwards remember absolutely 

 nothing. At last Dr. Kellas obtained my assent to raising the pres- 

 sure to 350 mm., after which I took up a mirror to look at my lips, 

 though Dr. Kellas observed that for some time I looked at the 

 back instead of the front of the mirror. I had, however, begun to 

 realize that we had been far longer at the low pressure than we 

 had intended, and agreed to a rise to 450 mm. On reaching this 

 pressure my mind had cleared and I noticed a return of feeling 

 and power in my legs. After coming out I could vaguely remember 

 taking up the mirror, but nothing before that, after handing over 

 the notebook. We had no intention of staying at so low a pressure 

 that it was impossible for me to take notes, and my persistence 

 was quite irrational. Dr. Kellas was much bluer than I was during 

 the stay at 320 mm., but could still write quite well, watch the ba- 

 rometer, and manage the regulating tap ; but whether he was quite 

 normal mentally seemed rather doubtful. Perhaps he shared to 

 some extent my irrational desire to continue the experiment: 

 otherwise I think he would have noticed how abnormal my condi- 

 tion was. We were both at the time unacclimatized to low pres- 

 sures. 



This personal experience illustrates some of the peculiar 

 dangers associated with atmospheres which produce anoxaemia, 



11 Haldane, Kellas, and Kennaway, Journ. of Physiol., LIII, p. 181, 1919. 



