H^MOCHROMOGEN - 19 



are very carefully set out. He states definitely that hsemochromogen 

 in his view is a chemical compound of hsematin (a salt or ester with a 

 nitrogenous substance). Yet the monograph was inaccessible, was ap- 

 parently little read, and got buried. In spite of its publication the teach- 

 ing three years ago was simply that when hsematin (C34H3QN404FeOH) 

 was reduced, reduced alkaline hsematin (C34H3oN404Fe) was obtained, 

 and that this body was identical with the substance hsemochromogen 

 obtained by making blood alkaline and then reducing it, and there- 

 fore that the characteristic spectrum of hsemochromogen was a 

 property of the material. 



So the matter stood when it was taken up in 1924 by Anson and 

 Mirsky(3), Their line of approach was an enquiry as to whether the 

 slight differences in the spectra of the hsemoglobins of various forms 

 of life were reflected in the spectra of the hsemochromogens obtained 

 by reducing these hsemoglobins in alkaline solution — Anson and 

 Mirsky being under the impression that the hsemochromogens were 

 protein-free substances. 



It soon appeared that the spectrum with the conspicuous band, and 

 the formula C34H3oN404Fe, did not belong to the same substance. The 

 formula was an attribute of one substance, the spectrum of another. 

 Which shall we designate by the term "hsemochromogen"? Anson 

 and Mirsky decided to keep the term "hsemochromogen" for the 

 material with the conspicuous band, in which case it could no longer 

 be applied to the substance with the formula C34H3oN404Fe. 



What then is the mistake which hitherto has vitiated our views 

 and made us attach the formula of one substance to the spectrum 

 of another ? The mistake is that we have not recognised that hsemo- 

 chromogen, prepared directly from hsemoglobin, like hsemoglobin 

 itself, is a conjugated protein. 



Suppose hsemochromogen be made in the way which has been 

 indicated by rendering blood alkaline and then by reducing the 

 alkaline fluid, it is clear that the protein is all present. The world 

 supposed that it had been split off from the iron-containing portion 

 of hsemoglobin, but the fact remains that any rigid separation of the 

 globin from the pigment means the loss of the hsemochromogen 

 spectrum. 



On the other hand, if C34H3oN404Fe be made from the crystals of 

 hsemin, the substance produced does not possess the spectrum of 

 hsemochromogen. Add globin to it in sufficient quantity and the 

 typical hsemochromogen spectrum appears. 



