The acquisition of oxygen by the blood in the lung 187 



Suppose -08% of CO was in the air inspired by the subject; when 

 he had been breathing the mixture long enough for equilibrium to 

 have been established, some of his blood was drawn, and the relative 

 quantities of oxyhaemoglobin and CO haemoglobin estimated, the 

 result being that there was 46 % of the latter and 54 % f tne former. 

 If we consult their curve (Fig. 97) it informs us that the oxygen and 

 CO must have exerted in the fluid, with which the haemoglobin was 

 in contact, pressures related in the proportion of '06 of CO to 20*9 of 

 oxygen. But the actual pressure of CO was '08 % of an atmosphere, 



20'9 

 therefore the oxygen pressure in the plasma was '08 x ^~= 27'9/ 



of an atmosphere For the sake of simplicity we have omitted a 

 slight correction for aqueous vapour, which does not affect the main 

 point, namely that the oxygen pressure in the plasma exceeds that 

 in the atmospheric air, and still more that in the alveolar air, being 

 in this experiment almost double the latter. 



Perhaps there was nothing more convincing about the researches 

 which we have described than the experiments with which they were 

 controlled. Their authors seemed to show not only that there was 

 evidence of secretion in the lung, but that under conditions of im- 

 paired vitality that secretion disappeared. Moreover, this aspect of 

 the question transferred the problem from one of merely theoretical 

 importance into one of great practical interest to the clinician, 

 for if the body depends upon the secretory activity of the lung, and 

 this is easily impaired, then the primary object of treatment in the 

 case of lung complaints should be a care for this precious function. 

 It should aim at the restoration of the lung from a condition analogous 

 to that of dyspepsia. 



Of mice for instance the authors say " After exposure to a cold 

 atmosphere for a short time their body temperature begins to fall, 

 particularly if they are exposed to a somewhat high percentage of 

 carbon monoxide, and they become torpid." It was easy to cool 

 down the surroundings of the mouse by placing the bottle containing 

 it in cold water. The result invariably was that the oxygen tension 

 went down to about 15 % of an atmosphere. 



In the light of more recent work I am not now greatly concerned 

 to quote the results of Haldane and Lorrain Smith at great length. 

 I am concerned to state the problem in such a way that the reader 

 shall be in a position to criticise it intelligently. 



Indeed for fifteen years it divided the physiological world in a 



