ON THE EVOLUTION OF HAEMOGLOBIN. 79 



however, differs from normal deoxidized hsematin in not 

 uniting with loosely combined oxygen when exposed to the 

 air. In order to raise it to an oxidized state, it is necessary 

 to add a minute quantity of potassic permanganate. The 

 well-marked absorption bands then disappear, but are again 

 developed by the addition of a deoxidizing reagent. This 

 spectrum is, however, not seen unless the solution be some- 

 what alkaline ; and when the natural bile is exposed some 

 time to the air, so as to become somewhat acid, the bands 

 may not be seen until a slight excess of ammonia has been 

 added. Hence clearly enough, as in the case of normal 

 hgematin, the above-named bands in the spectrum are charac- 

 teristic of the alkaline deoxidized solution, but this bile 

 pigment of Helix has a less affinity for loosely combined, 

 oxygen. Such then being the case, it is necessary to inquire 

 whether it be possible to change it into normal haematin, or 

 to alter both into one common product. 



As far as I have yet been able to ascertain, there are at 

 least three very distinctly different modifications of hsematin, 

 which, when iu an alkaline solution and deoxidized, give 

 spectra of almost exactly the same character, the bands are 

 at the same distance apart, but their centres are situated 

 in very materially different wave-length positions, as will be 

 seen from the following table : — 



Very dark Much fainter 



l)nnd. band. 



Bile pigment haematin .... 564J . . 532 



Fresh made nor.iial liEematiu from human blood 561^ . . 529 

 The same kept several years sealed up in a lube 556| . . 524:| 



On taking a small quantity of an aqueous solution of 

 human blood, adding ammonia, and boiling, we obtain a 

 brown solution of what I regard as normal hsematin. Adding 

 a little potassic sodic double tartrate, and deoxidizing with a 

 minute portion of ammonium ferrous sulphate, we obtain 

 the well-known spectrum of deoxidized hsematin. If, how- 

 ever, the boiled ammonical solution of blood be sealed up in 

 a glass tube and kept for several years, it becomes deoxidized 

 by its own decomposition, and the spectrum, though very 

 closely analogous, is not identical with that obtained on 

 deoxidizing the fresh made solution. Both bands are raised 

 towards the blue end to the extent of nearly five millionths of 

 a millemeter, the upper one being also made somewhat 

 broader. I may here say that these quantities are as dis- 

 tinct and easily measured with suitable apparatus as an equal 

 number of inches in the height of a man. 



According to the principle already named, such a relation 

 between the spectra indicates some definite change of the 



