166 SEQTIONAL'ADDRESSES. 



where y is the percentage satui'afcion and x the oxygen pressure. The 

 value of K is the measure of the af&nity of oxygen for lieemoglobin : 

 the less the value of K the less readily do the two substances unite. 



Now =- has been shown by Laurence J. Henderson,' and indepen- 

 dently by Adair, to vary directly with the concentration of COj. The 

 value of this constant is, according to Henderson, too gi'eat to be a 

 direct effect of the CO2 on the hsemoglobin, and involves as well the 

 assumption that the hsemoglobin in blood is in four forms — an acid 

 and a salt of reduced hsemoglobin and an acid and a salt of 

 oxyhaemoglobin. The presence of COo alters the balance of these four 

 substances. 



It is rather fashionable at present to say that ' the whole question 

 of acidosis and anoxaemia is in a hopeless muddle. ' To this I answer 

 that, if it is in a muddle, I believe the reason to be largely because 

 schools of thought have rallied round words and have taken sides under 

 the impression that they have no common ground. The ' muddle, ' 

 in so far as it exists, is not, I think, by any means hopeless; but I 

 grant freely enough that we are rather at the commencement than at 

 the end of the subject, that much thought and much research must 

 be given, firstly, in getting accurate data, and, secondly, on relating 

 cause and effect, before the whole subject will seem simple. No effort 

 should be spared to replace indirect by direct measurements. My own 

 inference with regard to changes of the reaction of the blood, based 

 on interpretations of the dissociation curve, should be checked by actual 

 hydrogen ion measurements, as has been done by Hasselbach and is 

 being done by Donegan and Parsons.' Meakins also is, I think, 

 doing great work by actually testing the assumptions made by Haldane 

 and himself as regards the oxygen in arterial blood. 



The Compensations for Anoxamia. 



For the anoxic type of anoxaemia two forms of compensation at 

 once suggest themselves. The one is increased hsemoglobin in the 

 blood; the other is increased blood-flow through tlie tissues. Let us, 

 along the lines of the calculations already made, endeavour to ascertain 

 how far these two types of compensation will really help. To go back 

 to the extreme anoxic case already cited, in which the hsemoglobin 

 was 66 per cent, saturated, let us, firstly, see what can be accomplished 

 by an increase of the hsemoglobin value of the blood. Such an increase 

 takes place, of course, at high altitudes. Let us suppose that the 

 increase is on the same gi'and scale as the anoxaemia, and that it is 

 sufficient to restore the actual quantity of oxygen in one c.c. of blood 

 to the normal. This, of course, means a rise in the hsemoglobin value 

 of the blood from 100 to 150 on the Gowers' scale. Yet even so great 

 an increase in the hsemoglobin will only increase the oxygen taken 

 up in the capillary from each c.c. of blood from '031 to '036 c.c, and 

 will therefore leave it far short of the '06 c.c. which every cubic centi- 

 metre of normal blood was giving to the tissue. So much, then, for 

 increased hsemoglobin. It gives a little, but only a little, respite. Let 

 us turn, therefore, to increased blood-flow. 



