Appendix I, On methods 297 



oxygen in the plasma. Such blood therefore when shaken with air at 1 5 C. will 

 take up '006 c.c. of oxygen per c.c. This also must be added to the reading obtained 

 above, which will bring it up to (0-063 + 0'006)=0'069 c.c. This therefore is the 

 corrected oxygen reading, and represents the oxygen in the blood from this animal, 

 which when cold will be practically entirely in the haemoglobin, when warm it will 

 have been to a trifling extent in the plasma. 



Determination of Percentage Saturation of Blood with oxygen 

 by means of tJie differential method. 



The percentage saturation is of course the quantity of oxygen which the blood 

 contains A, divided by the total oxygen capacity (7, multiplied by 100, i.e. 



A 



100X ^. 







We have already described methods for the estimation of A and C ; but as they 

 cannot both be performed upon the same sample of blood it is convenient to make 

 use of the following very simple device. 



If the blood in question be simply shaken with oxygen it will take up oxygen 

 until it becomes saturated. If the quantity which it originally held was A, and that 

 which it takes up on shaking was B, then 



B = C-A or A = C-B. 



The percentage saturation then is 



We proceed to measure C and B. Of these two measurements B is made first. 



Measurement of B. 



Place 2 c.c. of ammonia in each bottle, underneath the ammonia run 1 c.c. of the 

 blood to be estimated into the bottle on the left hand side (L) and 1 c.c. of saturated 

 blood (not necessarily from the same animal) in the right hand bottle (R). 



Grease the stoppers. 



It is most important that the stoppers should be thoroughly clean inside and free 

 from all traces of ferricyanide. 



See that the taps are open. 



Place the bottles on the stoppers and the apparatus in the bath. 



After five minutes read. Suppose the reading to be 



Left Bight 



120 119-5 



Close the taps ; see that the surfaces do not move for two mimites, then shake for 

 one minute, or until the unsaturated blood ceases to become redder. Replace in the 

 bath, after one minute read, shake again for one minute. Read and shake for 

 alternate minutes until the reading becomes constant. Suppose it then is 



Left Eight p 



129-5 110 19-5-0-5 = 19 mm. 



B then = 19. 



