Contribution to the Physiology of Respiration under the Arctic Climate. 139 



and the air-pressure can just as little play any part in the movement 

 as a whole. For the first four averages the temperature is respec- 

 tively 120°, 111°, 11-2° and 10-5° and the corresponding barometric 

 heights 759, 761, 762 and 757 mm. And during this period represented 

 by the months named the carbonic acid varies by 75 mm., i. e. a 

 reduction of 21-9^'/o reckoned from the value for February. 



The explanation must therefore be sought for elsewhere and it 

 is found — I believe — when we bring together my series of annual 

 variations with the results of the English and German investigations 

 in the High Alps. We then see, that there is a very great agreement 

 between the change occurring in the alveolar carbonic acid tension 

 on going from Copenhagen to North-East Greenland and that which 

 occurs on journeying from London or Berlin to the top of Monte Rosa. 



It may be added, that the same parallelism applies also to all 

 the other respiratory functions investigated, frequency, total volume 

 of air respired and metabolism. The agreement is so striking, that 

 it seems to be more than due to chance, when Ward on his return 

 from Zermatt found irregularly fluctuating values for his carbonic 

 acid tension, just as I had a much greater standard deviation in my 

 experimental group for November than in any of the remaining 

 series. I imagine that the greater deviation in my November ex- 

 periments was due to the lack of physiological equilibrium after the 

 preceding, fatiguing sledge-journey; but it is not excluded, that the 

 change in the carbonic acid tension may proceed uniformly in the 

 one direction, less regularly in the other. 



If the agreement in the series of values given above is more 

 than due to chance, as I believe, the hitherto prevailing explanation 

 of the results of the mountain experiments cannot be the right one; 

 since the air-pressure in North-East Greenland is not lower than in 

 Copenhagen, and there can therefore be no talk of lack of oxygen. 

 The changes must be due, at least in the main, to a factor common 

 to the two climates, and of such there is certainly only one which 

 can come into consideration, namely, the strong light rich in 

 ultraviolet rays, which is further strengthened by reflection 

 from the ice and snow. 



XLIV. 11 



