Contribution to the Physiology of Respiration under the Arctic Climate. 141 



As the sunlight is a factor, the action of which does not display 

 itself at once in its fullest extent, but on the other hand, once 

 manifest persists even a long time after the cessation of the light, it 

 is a mistake to attempt to show the influence of the light by making 

 experiments on the same day, partly in the sunshine, partly in the 

 shade, as Zuntz and Loewy have done. It agrees well with my 

 experiments, however, that the German investigators have found a 

 rise in the intensity of all the changes in the respiration on pro- 

 tracted stay in high altitudes, in spite of the fact, that the supposed 

 lack of oxygen does not increase but must rather be considered to 

 become less, on becoming accustomed to the high climate, as pointed 

 out by themselves. 



The minimum value of the carbonic acid tension in my experi- 

 ments does not fall in the summer solstice either; the movement 

 downwards is continued, at any rate so long as the sun is constantly 

 above the horizon. 



The second question which arises is this: why is the alveolar 

 carbonic acid tension less in Greenland in January than in Copen- 

 hagen in February? 



This question I am unable to answer satisfactorily; but various 

 causes seem to play some part in this regard. In the first place it 

 is doubtful, whether I have hit upon the maximum of the annual 

 period in the Greenland experiments; a good deal indicates that this 

 first occurs a month later. The sun appears in the middle of Feb- 

 ruary; but on the ship all is covered over and the lamps lit till 

 far on in March. The minimum period hardly occurs before the 

 end of August and it is just towards the end of this time that its 

 influence is most marked. 



It is not excluded, further, that the after-effects from the previous 

 light period are still present in the January experiments, as it was 

 just in the preceding autumn that I was out on the sledge-journey, 

 right until the sun disappeared and thus took as much advantage 

 of the diminishing light as possible. It must also be remarked that 

 the barometric pressure during this period of experimentation was 

 very low, almost 10 mm. lower than during the experiments in 

 Copenhagen; there can be no doubt that this is of some importance 

 in this connection. And lastly, the temperature may also play some 

 part; in the January experiments it was distinctly higher than at 

 the other periods when experiments were made. The weather at 

 this time was very broken and stormy, with abnormally high air- 

 temperatures for the time of year. I am unable here, as is the case 

 for the low temperature, to show definite experiments displaying the 

 influence of the temperature, but there is some probability, to judge 



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