22 4 



HEMOGLOBIN. 



been previously stated, in the case of oxyhaemoglobin, distinguished by 

 the symbols A Q and A\ ; the first has been determined for the spectral 

 region which lies between the two bands a and /3 of oxyhsemoglobin, 

 and is limited by \ 554 and x 565 ; the second has been determined for 

 the spectral region which corresponds to the darkest part of the second 

 (j8) band of oxyhaemoglobin, and extends from /. 531'5-X 542-5. 



SpectropJwtometric Constants of Oxyhcemoglobin 1 (Hufner). 



From the above constants we are able, as has been shown (see p. 215), 

 to determine the percentage of haemoglobin 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 haemoglobin 

 and oxyhaemoglobin 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. 



Hufner and his pupil v. Noorden long ago noticed that the quotient 



A ' ' 



L, which is the same as -, was remarkably constant, not only in 



-"0 ^0 



the blood of animals of the same species, but in all, however widely 

 separated in the animal scale. 2 Subsequent researches by Hufner and 

 his pupils, carried out with a much more perfect spectrophotoineter 

 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 150160 parts 

 of 01 solution of NaOH, or a solution in the same dilute NaOH of 

 crystals of oxyhsemoglobin of approximately equivalent concentration, 

 be thoroughly oxygenated by shaking with air and the values of S Q and 



z Q be determined, it will be found that the quotient will vary very 



2 <> 



slightly from 1'580. In very few determinations, out of a large number, 

 was it as low as 1'578. So soon, however, as the blood commences to 

 undergo any change, as, e.g., a partial conversion into methsemoglobin, 

 the coefficient is lowered. 



lr rhe values of A and A\ given above differ materially from those which had been 

 assigned to them previously by Hufner and his pupil v. Noorden as a result of researches 

 carried out with Hiifner's earlier and much less perfect spectrophotometer, and employing 

 haemoglobin which had been frequently recrystallised. 



2 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. Hufner in Tubingen), Ztschr.f.physiol. Chem., 

 Strassburg, 1880, Bd. iv. S. 9-35. 



