Contribution to the Physiology of Respiration under the Arctic Climate. 143 



carbonic acid tension to changes in the total volume of air passing 

 in and out of the lungs. 



Thus, whilst there is nothing in my experiments to indicate 

 that the variations in the air-pressure influence the total volume of 

 air respired, the effect of the cold is very clearly seen. For the 

 April experiments we have 



™ . Litres per hour 



Temperature (reduced) 



60° 453 



111° 485 



The standard deviation in the two groups, which include 6 and 

 7 experiments, is 8*5 and 1225 respectively. The difference is thus 

 significant. It appears further from the short series given on p. 104 

 that the total volume of air respired decreases considerably on the 

 first cold day and then rises uniformly on the following days. On 

 the cold days in May such an "adaptation" does not occur, as there 

 is a few days' interval between the three experiments. Quite a cor- 

 responding diminution in the total volume of air respired occurs in 

 experiment No. 66, as also in No. 55, but here the temperature is 

 not lower than at many other times, and I have noted nothing to 

 show that I felt the cold during the experiment. 



Lastly, it will be seen from the table on the day experiments, 

 that the total volume of air respired is on an average lower in May 

 than in November. Now the total volume of air respired was ad- 

 mittedly abnormally high during the period last-mentioned, but a 

 difference can be distinctly seen in the table corresponding to the 

 temperature. It is very marked, for example, in the groups for 9 

 a. m. and 3 p. m., where the difference of temperature is consider- 

 able, whereas we find the same total volume of air respired in the 

 two series in the group for 5 p. m., where the temperature is very 

 nearly the same. 



The annual fluctuations in the total volume of the air respired 

 will be seen from the following summary. 



Litres per hour 

 (reduced) 



Copenhagen, February 384 + 24, p. = 125 



N.E.Greenland, April (group II) 485 + 3-1, /^ = 1225 



— June 495 i 5-1, fx = 274 



— August 521 + 4-2, n = 19-5 



— November 522 ± 84, fi = 396 



— January 472 ± 35, ix = 178 



We thus have an annual period with its maximum at the time 

 when the alveolar carbonic acid tension has its minimum and vice 



