Contribution to the Pliysiolog}' of Respiration under tlie Arctic Climate. 135 



tension again follows the fluctuations of the barometer; the excep- 

 tions are but few. The variations in the air-pressure are very con- 

 siderable in this series; but the temperature is high and uniform. 

 Dividing the series according to the average height of the barometer 

 we obtain an average of ЗГ4 when the barometer is < 750, and 

 324 when the barometer is > 750, thus a decided difference, even 

 though not so well-marked as in the April experiments. 



It may be added, that the three experiments for May show the 

 same features. 



We can thus show a connection between the alveolar carbonic 

 acid tension and the air-pressure, both in the Danish and in the 

 Greenland experiments, most marked in the last, yet only for the 

 winter and spring experiments. This connection is undoubtedly the 

 rule. That it is specially distinct in the arctic winter harmonizes 

 well Avith the direct observation of its influence on the state of 

 health. These variations, never very considerable, are obscured in 

 the arctic summer; it will be shown below, that the latter also 

 exerts a levelling influence on the phenomena of respiration in other 

 ways, and that this influence, just as is the case here, persists until 

 the beginning of winter. 



The influence of changes in the air -tempe rature can 

 still less be calculated, partly because such an influence does not 

 appear at a definite temperature limit, partly because, as mentioned, 

 there never was the same temperature at the roof and on the floor 

 of the cabin; the difference in temperature might even be very 

 large. I can therefore indicate the temperature of the gas-meter but 

 not that of the layer of air round about me during the experiment; 

 regarding the latter I only know that it was always lower than the 

 gas-meter's and as a rule varied in the same direction as this. Nor 

 can I give the temperature of the inspired air; it passed through 

 a metal tube and was thus to a certain degree heated up before it 

 was inspired; but now and then I noticed that it was cold. 



The mean temperature of the place does not seem to have any 

 influence. If so, it should give higher carbonic acid tension in 

 winter than in summer in my Greenland experiments; but my con- 

 trol experiments in Copenhagen, which give a still higher carbonic 

 acid tension than the Greenland winter experiments, quite throw 

 cold water on such a view. It is obviously the temperature in one's 

 immediate surroundings during the experiment, which is of impor- 

 tance. And in this regard I must acknowledge the correctness of 

 Haldane's opinion, that it is not the temperature read on the ther- 

 mometer which is of importance, but on the contrary the purely 

 subjective feeling of discomfort under an unaccustomed temperature. 



