344 CO, Capacity of Blood. I 
Experiment 10.—Dog, male, 11 kilos. CO, administration. Procedure 
same as Experiments 8 and 9, but the CO, in bag was run up higher. 
Equilibrating air 5.5 per cent COs. 
; Blood COz. 
Time. Condition. Baan oR es Pete ho ae 
Content. Capacity. 
per cent vol. per cent | vol. per he sf Os 
11:30 a.m. | Normal. 48 50 39.9 
11.45 “ CO, started. 6.2 | 
Ie oe acs , 57 54 
LS sm: 67 60 
She ae 10.3 70 62 40.1 
PAT Gy os 72 66 
OLD cae 14.0 _ 79 65 
4.00 * 87 71 
4.45. - 20.0 86 74 42.0 
4.50 “ CO, stopped.* 
* After drawing a few breaths of fresh air the dog stopped breathing. 
The heart continued to beat for several minutes and then stopped. Died. 
Experiment 10 is extraordinary. The CO, in the air breathed 
reached 20 per cent. The CO, content of the blood rose to 86 
and the CO, capacity to 74. When the animal was finally allowed 
to breathe normal air again its respiration ceased after a few 
breaths and a fatal apnea followed. Apparently the alkali con- 
tent of the blood had been raised so high that when the abnor- 
mally high pressure of CO. was withdrawn the respiratory center 
’ Jacked an adequate stimulus. 
CONCLUSIONS. 
Whenever by means of morphine respiration is depressed and the 
alveolar COs, is raised, or whenever by the administration of CO. 
in the air breathed the CO, content of the blood is forced up, 
the CO, capacity (alkaline reserve) of the blood also rises. This 
rise is probably due to a compensatory passage of alkali from the 
tissues into the blood. Through this mechanism respiration 
exerts a powerful influence upon the ‘alkaline reserve”’ of the 
blood. 
