RESPIRATION 



201 



These differences are just what might be expected in view of the 

 action of haemoglobin as a weak acid in alkaline solutions. In spite 

 of the great differences in the dissociation curves of blood and 

 serum Hasselbalch's law held good. He therefore applied it as a 

 means of calculating the hydrogen ion concentration of corpuscles 

 and of abnormal blood, and seemed justified in doing so. 



Vol % 



10 tO 30 40 50 60 70 SO SO 



. Serum, 38 



Blood, 1 8 

 Blood, 38 

 Blood corpuscles, 38 

 Serum, 18 



Figure 58. 

 COa dissociation curves (from Hasselbalch loc. cit.) 



Nevertheless this method, like that of Barcroft and Peters, 

 seems to break down with abnormal blood. As an example of 

 abnormal blood he took, from the paper already referred to by 

 Christiansen, Douglas, and myself, experiments in which Douglas 

 had flooded his blood with lactic acid by running quickly a number 

 of times up and down the laboratory stairs at intervals during 

 about a quarter of an hour. As a consequence his blood had lost 

 about 40 per cent of its normal power of combining with CO 2 , and 

 his resting alveolar CO 2 pressure was diminished by about a fifth. 

 The samples were taken about ten minutes after the last ascent of 

 the stairs, and all sensible hyperpnoea had passed off. From the 

 data given, Hasselbalch calculates, in accordance with the law 

 he had discovered for the same blood at varying pressures of CO 2 , 

 that the PH of Douglas's arterial blood had fallen by .12. This 

 would, in accordance with the data given above as to the effects 

 of increase of PH on the breathing, suffice to increase the breath- 

 ing to about ten times its resting value. Indeed Hasselbalch evi- 

 dently believed that there must have been such an increase, since 

 he speaks of the immensely increased breathing being unable to 

 compensate for the decrease in PH. The breathing was, however, 

 perfectly quiet and apparently normal, though the lowering of 



