1 90 HsEMO GL OB IN. 
Hypothesis of Hoppe-Seyler, that the coloured substance of the 
corpuscles possesses properties which differ from those of haemo- 
globin — Arterin (?), and Phlebin (?). — It has been shown that we are 
forced to assume the existence in the coloured corpuscles of a very unstable 
compound of haemoglobin. Hoppe-Seyler, as far back as 1877, l expressed the 
opinion that whilst the compound or compounds of haemoglobin existing in the 
blood corpuscles absorb the rays of the spectrum precisely as solutions of 
haemoglobin, in other respects very remarkable differences can be detected, 
certain of these differences being, in bis opinion, of great physiological 
importance. 
Subsequently, 2 Hoppe-Seyler, returning to this subject, endeavoured to 
prove by a variety of arguments that such are the differences between the 
properties of the colouring matter as it exists in the coloured corpuscles and 
pure haemoglobin, that Ave cannot logically assert that they are identical. He 
examined in detail the differences in behaviour which had been observed by 
himself and by others, between the blood-colouring matter as it exists in the 
corpuscles and solutions of pure oxy- or reduced haemoglobin. He referred to 
the undoubted fact that the colouring matter, as it exists in the coloured 
corpuscles, is not dissolved out by serum, liquor sanguinis, or saline solutions, 
of a certain strength. It does not, he alleged, crystallise, nor readily yield 
its dissociable oxygen when heated in vacuo ; it readily decomposes peroxide 
of hydrogen (H.,0.,), setting free ordinary inactive oxygen, and is not oxidised 
during the process ; a solution of potassium ferricyanide does not for a long 
time attack the blood corpuscles, or convert their colouring matter into 
methaemoglobin. 
On the other hand, a solution of oxyhsemoglobin (or, as Hoppe-Seyler 
preferred to express it, of the oxyhemoglobins, so as to recall the fact of the 
minor differences presented by the haemoglobin of different species of animals) 
is soluble in serum or in blood plasma, or in solutions of the neutral salts ; 
it crystallises with greater or less facility, according to the animal whence 
the blood is obtained. When thoroughly pure, it has scarcely any power 
of decomposing H 2 0.„ but under the influence of this body it is readily 
oxidised. 
Solutions of crystallised oxyhaemoglobin, Hoppe-Seyler maintained, give 
up their dissociable oxygen with difficulty and incompletely, when heated 
in vacuo. When blood is saturated with CO, this gas can subsequently be 
entirely removed, by passing a stream of hydrogen gas through it for some 
hours, or by long-continued boiling in vacuo. On the other hand, when a 
solution of oxyhaemoglobin is saturated with CO, and the solution is heated 
in vacuo, the poisonous gas is, Hoppe-Seyler stated, given off with great 
difficulty and incompletely. 
Lastly, highly dilute solutions of potassium ferricyanide readily convert the 
oxyhemoglobins into methaemoglobin. 
The evidence by which Hoppe-Seyler endeavoured to prove that the 
properties of the blood-colouring matter, as it exists in the corpuscles, differ so 
oTeatly from those of haemoglobin, that we cannot with truth say that this 
body exists in them, is, on every single point, of so unsatisfactory a character 
as not to stand a moment's investigation, and would lead us to reject his 
hypothesis, even if we had not been placed in possession of some remarkable 
farts 1 leaving on this subject, which have been ascertained by the method of 
spectrophotometry. The non-crystallisation of the colouring matter as it 
exists in the coloured corpuscles might, were it really true, well be explained 
by the fact that haemoglobin does not exist in a free state, but is combined 
1 " Physiologische Chemie," Berlin, 1877, Th. 1, S. 381. 
- "Beitrage zur Kenntniss des Blutfarbstoffes," Ztschr. f. physiol. Ohem., Strassburg, 
1889, Bd. xiii. S. 477. 
