Contribution to the Physiolog}' of Respiration under tlie Arctic Climate. 81 



desire to be active and we could work. We went unwillingly to 

 bed, preferring to sleep just as the occasion offered; the sleep was 

 short yet refreshing. One had the feeling of never resting and 

 never tiring, which contrasted strongly with ths psychical helpless- 

 ness of the dark period. We were disposed to be friendly towards 

 one another, very willing to listen and likewise to talk. 



With regard to the transition-periods, the spring was charac- 

 terized at one and the same time by strong light and severe cold. 

 We thus had the opportunity of convincing ourselves of the fact, 

 that the temperature variations have but small influence on the 

 health in comparison with that exerted by changes in the intensity 

 of the light. 



As my experience during the first arctic winter had thus led 

 me to the conviction, that this, apart from a number of collateral 

 causes, had a deep-going influence on my state of health, I came 

 to the reasonable conclusion, that it would also have some effect on 

 the respiration, whatever the summer might show. The more so, 

 as my scattered observations had already indicated some factors in 

 the physiological basis for the condition. 



My plan was to make respiration experiments every two months 

 throughout the year; but the conditions on the Expedition, journeys 

 etc., made me alter my plan a little; instead of 6 series I obtained 

 only 5, as Г twice had an interval of 3 months. The observations 

 fall, however, to some extent at the periods of the year, when the 

 most marked differences were to be expected. 



It was originally Hasselbalch's discovery of the effect of light 

 on the frequency of respiration and the blood-pressure, which led 

 me to the idea, that these functions must also undergo change in 

 the arctic regions according to the time of year; I expected especi- 

 ally to find during the dark period a change in the opposite direc- 

 tion to that discovered by Hasselbalch. I also thought it possible 

 that I might be able to contribute something towards the solution 

 of the vexed question of the influence of light on metabolism. And 

 lastly, it was my intention to test whether Haldane and Priestley's 

 hypothesis, that the COo-tension in the alveoli is an approximately 

 constant quantity under varying conditions of life, would also hold 

 good under the very different conditions met with on an arctic 

 expedition. 



During the preliminary experiments, which seemed to support 

 my supposition with regard to the effect on the respiration-frequency 

 and blood-pressure, I became aware of a relation between the fre- 

 quency and the air-pressure. Any definite effect of the temperature I 



