Blood Oxygen Analyses. 



211 



control of hydrogen ion concentration is absolutely essential 

 before valid conclusions can be drawn as to the influence of electro- 

 lytes, alone or in combination. 



Furthermore, it is essential to follow with care the changes 

 which go on in a suspension of living and dead cells as well as to 

 determine the initial conditions which are provided. We find 

 that a bacterial suspension in 5 isotonic NaCl solution quickly 

 reverts to a pH of about 7.2 whether its initial hydrogen ion 

 concentration be above or below this value. A similar change takes 

 place in a balanced solution of 5 isotonic NaCl + isotonic CaCl 2 

 but at a much slower rate as indicated by the table below. 



Hydrogen Ion Concentration of Suspensions of Bad. coli in the Presence 



of Electrolytes. 



Initial. 



5 



Isotonic NaCl. 



Initial. 



5 Isotonic NaCl + Isotonic CaCli. 



4 A Hrs. 



9 Hrs. 



30 Hrs. 



4* Hrs. 



9 Hrs. 



24 Hrs. 



4.0 



7.0 



7.0 



7.2 



4-0 



4.8 



4.8 



5-8 



5-0 



7-3 



7-2 



7-2 



5-0 



6.5 



6-5 



7-2 



6.0 



7-5 



7-2 



7-2 



6.0 



7.2 



7-2 



7-1 



7.0 



7.2 



7-0 



7-4 



7-0 



7-2 



7-2 



7-5 



8.0 



7.2 



7.2 



7.2 



8.0 



8.0 



8.0 



8.0 



116 (1576) 



Discrepancies in blood oxygen analyses by the methods of Van 

 Slyke and Henderson-Smith. 1 



By Arthur H. Smith, J. A. Dawson and Barnett Cohen. 



[From the Sheffield Laboratory of Physiological Chemistry, Osbom 

 Zoological Laboratory and the Laboratory of Public Health, Yale 

 University, New Haven.] 



Loosely bound oxygen is liberated from the hemoglobin in 

 blood by the addition of potassium ferricyanide. In the Van 

 Slyke method, 2 all the gases are exhausted by means of a Toricellian 

 vacuum from a laked blood-ferricyanide mixture and measured 

 directly. In the Henderson-Smith method, 3 the oxygen is evolved 



1 This work was initiated in the Laboratory of Intermediary Metabolism, Chemi- 

 cal Warfare Service, Yale Station, under Lt.-Col. F. P. Underhill. 



2 Van Slyke, D. D., Jour. Biol. Chem., 1918, XXXIII, 127. 



3 Henderson, Y., and Smith, A. H. f Jour. Biol. Chem., 1918, XXXIII, 39. 



