S. Kuriyama Ale 
vigorously aerated, and the reaction thus changed, which now 
served as an index of the alkali reserve of the blood, was again 
estimated colorimetrically. The CO: capacity of the plasma was 
determined by Van Slyke and Cullen’s method,® the larger size 
apparatus® being used. ‘The results were calculated so that they 
showed cc. of CO2 reduced to 0°C., and 760 mm. Hg, bound as 
bicarbonate in 100 cc. of the plasma. The blood was collected 
from the external jugular vein by a needle connecting to a cannula 
passing to the bottom of a centrifuge tube containing potassium 
oxalate and a layer of paraffin oil. No anesthetic was used. 
During the operation the rabbit was kept quiet so as not to dis- 
turb the circulation and respiration. 8 or 9 cc. of the venous 
blood were collected at once. After mixing with the oxalate, 
part of it was taken out for dialysis and the rest was centrifuged 
for obtaining the plasma. ‘The same vein could be used for sev- 
eral punctures. But if thrombosis occurred, the vein on the 
other side was used. The blood was examined usually in the 
morning. When this was done twice a day, the first examination 
was made in the morning and the second one in the afternoon 
after thyroid feeding. On the first experimental day, the blocd 
examination was made before changing foodstuffs or before the 
first thyroid feeding. The results of this day, therefore, can be 
considered the normal value. The results are shown in Tables 
I and II, and Charts I and II. 
From these results it will be seen that the hydrogen ion con- 
centration of the normal rabbit blood is pH 7.35 to 7.5. The 
kind of food caused no noteworthy difference. After aeration 
of the dialysate the value became pH 8.1 to 8.2. Levy and his 
coworkers! reported that pH of the oxalated blood from normal 
men varies from 7.4 to 7.6. This is nearly the same as my re- 
sults with the rabbit blood. When thyroid was given to the 
oat-fed rabbits, the hydrogen ion concentration of the blood 
slightly increased (the maximum, pH 7.25 to 7.3). In the blood 
of acidosis patients, Levy and his coworkers!® observed a reac- 
tion of pH 7.1 to 7.4; therefore nearly the same degree of acidosis 
as found in my thyroid-fed rabbits. A slight decrease of the 
® Van Slyke, D. D., J. Biol. Chem., 1917, xxx, 347. 
10 Levy, R. L., Rowntree, L. G., and Marriott, W. McK., Arch. Int. 
Med., 1915, xvi, 389. 
