224 
H.-EMOGLOBIX. 
been previously stated, in the case of oxyhemoglobin, distinguished by 
the symbols A and A' : the first has been determined for the spectral 
region which lies between the two bands a and j3 of oxyhemoglobin, 
and is limited by X 554 and /. 565 ; the second has been determined for 
the spectral region which corresponds to the darkest part of the second 
(,S) band of oxyhemoglobin, and extends from '/. 531 "5-/. 542*5. 
Spectrophotometry Constants of Oxyhemoglobin* {Hiifner). 
Limits of Spectral Region in which 
f n and e' were determined. 
(i2ofe ) . . X554-X565 
(iJofe' ) . \ 531 -5-X 542-5 
Absorption relation A and -4' corre- 
sponding to the two regions. 
A' 
0-002070 
0-00131-2 
From the above constants we are able, as has been shown (see p. 215), 
to determine the percentage of hemoglobin in the blood with surprising 
accuracy. The further use of these constants will be referred to in 
explaining the mode of determining the relative amounts of hemoglobin 
and oxyhemoglobin coexisting in any .sample of blood. 
We have now to consider in some detail the light which spectro- 
photometry has shed on certain questions which possess great interest 
to the physiologist, and which have up to a certain point been already 
discussed in this article. 
Hiifner and his pupil v. Noorden long ago noticed that the quotient 
A' i 
'—, which is the same as — -, was remarkably constant, not only in 
A £o 
the blood of animals of the same species, but in all, however widely 
separated in the animal scale. 2 Subsequent researches by Hiifner and 
his pupils, carried out with a much more perfect spectrophotometer 
than the one employed by v. Noorden and himself, more than confirm 
the earlier results in so far as the constancy of the quotient is 
concerned. 
If the defibrinated blood of any animal, diluted with 150-160 parts 
of 01 solution of XaOH, or a solution in the same dilute XaOH of 
crystals of oxyhemoglobin of approximately equivalent concentration, 
be thoroughly oxygenated by shaking with air and the values of s and 
c 
g'„ be determined, it will Lie found that the quotient — will vary very 
So 
slightly from l - 580. In very few determinations, out of a large number, 
was it as low as T57S. So soon, however, as the blood commences to 
undergo any change, as, e.g., a partial conversion into methemoglobin, 
the coefficient is lowered. 
1 The values of A and A' g given above differ materially from those which had been 
assigned to them previously by Hiifner and his pupil v. Xoorden as a result of researches 
carried out with Hiifner's earlier and much less perfect spectrophotometer, and employing 
haemoglobin which had been frequently re rystallised. 
- v. Noorden's observations included the blood of man, the dog, the cat, the rat, the 
guinea-pig. and the owl. " Beitrage zur quantitativen Spektralanalyse, in besondere zu 
derjenigen des Blutes" (aus d. Lab. d. Prof. Hiifner in Tubingen), Ztschr. f. physiol. Chcm., 
Strassburg, 1880, Bd. iv. S. 9-35. 
