234 Chapter XV 



value of K remains unchanged at '00025. This represents the reaction 

 of the blood. Such were the samples of Higgins' blood which have 

 been considered so far. 



Now take two specific cases V and VI. Let me compare them 

 with (I), the normal blood. 



The normal blood I, exposed to no C0 2 pressure, gives a value 

 for K of '0025 and exposed to the CO 2 of the normal alveolar air of 

 the patient (40 mm.) gives a value of '00025 for K. Either of these 

 may be found by a single determination of the percentage saturation 

 y at an oxygen pressure of oc. Then, taking n, the number of 

 molecules y aggregated together, as 2 '5, 



y Kx n 



100 == l 



x n (lOO-y)' 



With this compare blood V. The alveolar C0 2 is found to be 

 27 mm. A point on the dissociation curve is found in the presence 

 of this quantity of C0 2 . It also gives the value of '00025 for K, 

 therefore the blood is mesectic. Now some of blood V is taken again 

 for the purpose of determining the acidosis. Free from CO 2 , it 

 gives a value of K = '00065. From this it is clear that the amount of 

 the acidosis is equivalent to about '07 / lactic acid. Now pass to 

 blood VI. The alveolar C0 2 is also found to be 27 mm. Exposed to 

 27 mm. C0 2 the value of K works out to be '00024. The blood is 

 therefore off the line, it is meionectic. The value of K in the absence 

 of CO 2 is '00075. This corresponds to an acidosis equivalent to '085 / 

 lactic acid. In this case therefore the acidosis and the CO 2 together 

 amount to more than the original C0 2 . Blood VI being meionectic 

 the respiratory centre would be stimulated ; blood V being mesectic 

 the respiratory centre would not be stimulated. 



In all the cases I, III, V and VII, not only would the blood be 

 mesectic, since K remained normal, but the rhythm of the respi- 

 ratory centre and no doubt a hundred other things would remain 

 normal also. 



Now consider another series, I, II, IV, VI. In this as in the first 

 the alveolar CO 2 decreases progressively, but the value of K decreases 

 also, since the aggregate of floating acids increases. In this case the 

 blood would become increasingly more meionectic and the respiratory 

 centre would become increasingly active. 



