198 BIOLOGICAL PROBLEMS 



ologist, Paul Bert, not to wait until too great a height 

 was attained before taking oxygen. 



It may be pointed out in passing that such accidents 

 are not possible at the heights at present attained by 

 aeroplanes. 



Mountain sickness is characterized in most subjects 

 by headaches, nausea, and distress in breathing, 

 especially on exertion. After a period of seven to 

 ten days acclimatization takes place, mainly due to a 

 new formation of haemoglobin, the oxygen-carrying 

 pigment of the blood, or to an increased number of 

 red blood corpuscles. Also, after the first few hours, 

 an attempt at acclimatization is made, in so far as 

 the blood is concentrated by a diminution in the 

 'amount of its watery portion, the plasma, so that 

 its oxygen-carrying capacity is thereby relatively in- 

 creased. 



In flying, even in a first flight, provided no alarming 

 evolutions are indulged in, there is at first little or no 

 sensation beyond the sheer enjoyment experienced in 

 rising higher and higher above the fast-receding 

 earth. The depth of respiration is gradually but im- 

 perceptibly increased, until, at a height of 12,000 to 

 15,000 feet, almost everybody breathes through the 

 mouth as well as through the nose. Following the 

 deepening of respiration there is a quickening of 

 the pulse, and, as the height is increased, a rise in 

 the blood pressure. When a great altitude is reached, 

 there appear, varying in different subjects at heights 

 from 15,000 to 21,000 feet, muscular weakness and 

 subjective and objective nervous sensations. Less 

 often there is nausea and occasionally vomiting. 



Before the use of oxygen at high altitudes it was 

 not an uncommon occurrence for an airman who went 

 to photograph at altitudes of 20,000 feet or more to 

 believe from the results attained that his camera had 



