COMPOUNDS OF HAEMOGLOBIN WITH GASES. 237 
Non-existence of the so-called " pseudo-haemoglobin." — After 
treating blood with reducing agents until the two bands of oxyhemoglobin 
were no longer visible, Siegfried ' found that there yet remained oxygen 
removable by boiling in a barometric vacuum. He therefore concluded that, 
in addition to oxyhemoglobin, 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- 
ha nioijlohiii. 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 T and e',. so as to ascertain the 
quotient — which should = 0*7617. 
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 Haemoglobin with Carbonic Oxide and Nitric 
Oxide, and their relation to Oxyhemoglobin. 
Introductory remarks. — In a previous part of this article, I have 
referred to oxyhemoglobin 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 oxyhemoglobin, and, in a measure, on the 
function subserved by it, although this subject will be more fully dis- 
cussed under the heading of " Eespiration." 
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, "Arch./. Physiol., Leipzig, 1S90, Phys. Abth., S. 385. 
2 " Bestimmung der Sauerstoffcapacitat des Blutfarbstoft's," ibid., 1894, Phys. Abth. 
S. 140 and 175. 
3 " Lecons sur les efTets des substances toxiques et meMicamenteuses, " Paris, 1857, 
p. 158 ; also " Propriety des liq. de l'organisnie, " Paris, 1859, tome i. p. S55. 
4 "Ueber die Einwirkung des Kohlenoxydgases auf das Hamatoglobulin," Virehow's 
Arehiv, 1857, Bd. xi. S. 288. 
s "Die Gase des Blutes," Guttingen, 1857; and Ztsckr. f. rat. Med., 1858, S. 256; 
" De sanguine oxydo earbonico infecto," Diss. Inaug., Vratislavice, 1858. 
