CHAPTER VII 



THE MANUFACTURE OF HAEMOGLOBIN 



JLhe specific oxygen capacity of haemoglobin can be determined 

 with accuracy on "whole blood " because there is in that fluid no other 

 substance which contains an appreciable quantity of iron. If the 

 properties of the pigment are to be examined in detail it is necessary 

 to have some definite ideas about the preparation of the pigment in 

 a state of purity. It is at this point that haemoglobin begins to present 

 those elusive quahties which conspire to make it "perhaps the most 

 interesting substance in the world." Could we, once and for all, give 

 a complete statement of why haemoglobin on aU occasions acts as 

 it does, we should have made strides with seven league boots through 

 the realm of colloid chemistry, and more than that — it is possible 

 that we should have shortened to an appreciable extent the journey 

 which must be traversed before we obtain any true insight into- the 

 difference between living and dead matter. 



The classical method for the preparation of haemoglobin is some- 

 what as follows. You obtain blood from some animal the haemo- 

 globin of which crystallises out with ease. Here then is a crop of 

 problems as yet quite unsolved : Why does the blood of some animals 

 crystallise more readily than that of others? On what property of 

 the haemoglobin does its tendency to form crystals depend ? Why are 

 the crystals from the bloods of different animals, and even from the 

 blood of the same animal j of different forms? We attribute the dif- 

 ference to the globin, and for the present we must let the matter 

 pass with the statement that the blood of the rat crystallises with 

 great ease, e.g. on the addition of distilled water, and that the horse 

 and dog are the animals from which it is most easy to obtain haemo- 

 globin crystals in bulk. Indeed crystals of haemoglobin may be pre- 

 pared from horse blood by a process no more elaborate than that 

 of passing the blood through a Sharpless separator (i) reputed to 

 revolve at 17,000 revolutions per minute; this procedure we have 

 seen in Prof, Laurence J. Henderson's laboratory. To return to the 

 classical method, starting with the blood of the horse, or if such 

 cannot be obtained then the blood of the dog — but in no wise using 

 the blood of the ox, sheep or pig, for they do not readily crystalUse — 



