24 Chapter II 



subject. Moreover it presents another very attractive feature. The 

 difference between oxyhaemoglobin and the body believed to be 

 isomeric with it, methaemoglobin, has always been somewhat of 

 a mystery. It would therefore be a relief to regard methaemo- 

 globin (6) as a chemical compound of oxygen and haemoglobin, whilst 

 oxyhaemoglobin was a physical combination of the two bodies. 



Before dealing with the matter at greater length we should make 

 it clear that on the adsorption theory there is no reason why the two 

 bodies should be isomeric. The amount of oxygen which haemo- 

 globin should unite with has not a fixed limit on this theory. The 

 relationship which we have pointed out in Chapter I, that of the 

 oxygen and the haemoglobin being united in proportion to two 

 atoms of the one to one molecule of the other, would be a purely 

 accidental one with particular significance. 



The adsorption theory of oxyhaemoglobin was originally put for- 

 ward merely as an explanation of the facts then known, but not in any 

 way as the result of experiments intended to show that it was more 

 likely to be correct than the chemical theory. 



Since its advent, however, a very laborious research has been 

 carried out by Manchot' 7 ' which must be considered, for if the 

 experimental evidence advanced by this worker can be accepted it 

 could be most easily interpreted along the lines of this adsorption 

 theory. The point which is fundamental to Manchot's work is 

 that the amount of oxygen with which 1 gram of haemoglobin can 

 unite is dependent upon the concentration of the haemoglobin 

 solution. Up to a certain point the more dilute the haemo- 

 globin solution the greater the quantity of oxygen it can unite 

 with proportionally. Manchot's method was somewhat as follows : 

 (1) he reduced the blood used, till it no longer gave the oxyhaemo- 

 globin bands, (2) he then diluted it with various fluids, shook the 

 solutions with oxygen and measured the amount absorbed. The 

 experimental procedure failed to satisfy us on two counts : (1) we 

 do not regard the spectroscope as a satisfactory index of the initial 

 reduction, (2) no attempt was made to test whether the haemoglobin 

 at the end would yield, to a vacuum or to ferricyanide, the amounts 

 of oxygen alleged to have been taken up by adsorption. Burn (S) has 

 been at great pains to verify Manchot's results, having due regard to 

 the conditions just stated. He reduced the blood with the pump till 

 no more gas came off. He then determined the amount of gas which 

 1 c.c. of blood would absorb when shaken with air in the differential 



