COMPOUNDS OF HEMOGLOBIN WITH GASES. 237 



Non-existence of the so-called " pseudo-haemoglobin." After 

 treating blood with reducing agents until the two bands of oxyhaemoglobin 

 were no longer visible, Siegfried 1 found that there yet remained oxygen 

 removable by boiling in a barometric vacuum. He therefore concluded that, 

 in addition to oxyhsemoglobin, there existed another oxygen compound of 

 haemoglobin, and that this is characterised by the same absorption spectrum as 

 reduced haemoglobin. To this hypothetical body he gave the name of pseudo- 

 luemogloljin. Its existence has been absolutely disproved by Hiifner. 2 The 

 mistake into which Siegfried fell illustrates the danger of drawing conclusions 

 from qualitative spectroscopic observations. Hiifner has shown that without 

 spectrophotometric determinations it is impossible to know whether a solution 

 of blood or of haemoglobin is completely reduced. The only reliable criterion 

 is to be obtained by determining the values of e r and e' r so as to ascertain the 



quotient which should = 0'76 17. 



e r 



Blood which has been proved to be completely reduced in this manner, 

 yields no trace of oxygen when boiled in a mercurial pump. 



THE COMPOUNDS OF HEMOGLOBIN WITH CARBONIC OXIDE AND NITRIC 

 OXIDE, AND THEIR RELATION TO OXYHSEMOGLOBIN. 



Introductory remarks. In a previous part of this article, I have 

 referred to oxyhsemoglobin as an easily dissociated compound, formed 

 by the linking of one molecule of oxygen to a molecule of the highly 

 complex, iron-containing, crystalline colouring matter, "haemoglobin," 

 and I have subsequently shown that this conception has received con- 

 firmation through the fine researches of Hiifner on the molecular 

 weight of haemoglobin and on the volume of oxygen with which it 

 can combine. In the present section, reference must be made to ad- 

 ditional facts which, besides possessing an interest of their own, throw 

 fresh light on the nature of oxyhsemoglobin, and, in a measure, on the 

 function subserved by it, although this subject will be more fully dis- 

 cussed under the heading of " Respiration." 



It had been noticed independently by Claude Bernard 3 and by Hoppe, 4 

 that blood which had been treated with carbonic oxide, or the blood of 

 men and animals asphyxiated by charcoal fumes, presents an intensely bright 

 arterial colour, but that, unlike arterial blood, it does not in a few hours change 

 to a venous hue, but retains its vermilion tint for long periods of time. The 

 idea forced itself on the minds of both Claude Bernard and Hoppe, that through 

 the action of CO the power which the coloured corpuscles possess of acting as 

 oxygen-carriers had in some way been interfered with. Claude Bernard has, 

 however, the merit of being the first to show that, when brought in contact 

 with the blood, CO is absorbed and displaces oxygen ; and he afterwards based 

 upon these facts a method for the quantitative determination of the oxygen of 

 the blood. 



At the same time as, and independently of, Bernard, Lothar Meyer 5 



1 "Ueber Hamoglobin/'^rc/i. /. Physiol., Leipzig, 1890, Phys. Abtli., S. 385. 



2 " Bestimmung der Sauerstoffcapacitiit des Blutfarbstoffs," ibid., 1894, Phys. Abth., 

 S. 140 and 175. 



3 " Lemons sur les effets des substances toxiques et me'dicamenteuses," Paris, 1857, 

 p. 158 ; also " Proprie'te's des liq. de 1'organisme," Paris, 1859, tome i, p. 355. 



4 "Ueber die Einwirkung des Kohlenoxydgases auf das Hamatoglobulin, " Virchow's 

 Archiv, 1857, Bd. xi. S. 288. 



5 "Die Gase des Blutes," Gottingen, 1857; and Ztschr. f. rat. Med., 1858, S. 256; 

 "De sanguine oxydo carbonico infecto," Diss. Inaug., Vratislavice, 1858. 



