Contribution to the Physiology of Respiration under the Arctic Climate. 129 



physiological "constants" varies according to definite laws under the 

 influence of physiological and climatological factors. 



Haldane and Boycott ^ find that the alveolar carbonic acid 

 tension falls and rises with transition from cold to warmth and 

 conversely. They believe, in opposition to Scott ^, that there is no 

 connection between this phenomenon and the fluctuations in the 

 rectal temperature, but that it is due to a reflex action on the centre 

 from the skin of the face and hands. In this connection they speak 

 of the possibility of an annual periodicity Avith the lowest values 

 in summer; the observations are however but few and scattered. 

 The authors do not believe, that the fall in the tension begins at a 

 definite temperature, but rather, that it occurs when the warmth or 

 cold is felt as somewhat unpleasant. 



It is already mentioned in Haldane and Priestley's work, that 

 very great changes in the air-pressure are the cause of variations in 

 the composition of the alveolar air, whereas this is not affected by 

 ordinary, so-called normal fluctuations of the barometer. Haldane 

 and Boycott have now investigated this condition more closely in 

 a pneumatic room and have come to the result, that the carbonic 

 acid tension remains constant until a total pressure of ca. 550 mm. 

 during experiments of short duration. When the pressure further 

 decreases, the carbonic acid tension also falls. If a sufficient amount 

 of pure oxj'gen is introduced the pressure can go down to 307 mm. 

 without the carbonic acid tension changing. In experiments of 

 longer duration, on the other hand, the carbonic acid tension falls 

 a comparatively large amount and the effect lasts longer; after 20 

 hours the tension had fallen 7 mm. against 1 — Г5тт. in an experi- 

 ment of short duration, and the effect only disappeared after some days. 



Ward took part in these experiments and undertook a journey 

 later to Monte Rosa, in order to test, if the results obtained experi- 

 mentally would hold good. 



Ward came to the following results-^: 



London before the journey 



Zermatt, ^Лт 07 



Cap. Regina Margherita 



Zermatt 



Oxford, November 07 



The Journal of Physiology. Vol. XXXVII, 1908. 



ibid. 



ibid. 



