X METHJEMOGLOBIN 495 



oxyhtemoglobin, it will also show the two absorption bands of the 

 latter lying between D and E (see p. 480). (Ray-Lankester, 1 Araki, 

 and Menzies.-) In the extreme violet Gamgee has described a band 

 identical with that found in oxyhsemoglobin, and therefore probably 

 also due to oxyhsemoglobin. According to Gamgee, the band in the 

 violet lies between h and L. In greatly diluted solutions it is 

 restricted to between K and H, in stronger solution it extends to 

 M, and in very strong ones into the ultraviolet. 



Alkaline metha3moglobin possesses, according to Jiiderholm, three 

 bands, two on either side of the D-line, which frequently become con- 

 fluent, and a third at E. Their respective centres lie at 



A602; A578; A539. 



In solutions so strong that the two first bands become confluent, an 

 absorption-band is seen on the violet side of the D-line, which crosses 

 the D-line and extends up to the red. 3 This band and that at E 

 correspond again with those found in oxyhsemoglobin. v. Zeynek 

 has examined alkaline methsemoglobin solutions spectro-photometri- 

 cally; the absorption-quotient measured at the same place as in 

 oxyhaemoglobin is 1'185 ; the absorptive power of methsemoglobin is 

 therefore considerably less than that of oxyha3moglobin, a factor 

 which may have to be taken into account under certain conditions. 



Haldane has pointed out to the author that neutral methsemo- 

 globin solutions really consist of a mixture of alkaline and of acid 

 methsemoglobins, for on faintly acidifying a neutral solution by 

 shaking with expired air, containing about 4 per cent of C0 2 , the 

 band of alkaline hsematin is wiped out, unless oxy- or nitric-oxide- 

 hsemoglobin be present. 4 Haldane has also observed that a met- 

 hsemoglobin solution made by diluting blood with water, if subjected 

 to the vacuum, shows, as soon as the CO 2 has been boiled out, the 

 spectrum of alkaline methsemoglobin. If air is allowed to come into 

 contact with this methemoglobin solution it is reconverted into 

 neutral metha3moglobin. 



Photo-methaemoglobin is discussed under cyan-methaemoglobin. 



[A cid-hwmoglobin] 



Hemoglobin is dissociated by stronger acids in a short time into 

 tematin and globin, but if feeble organic acids or exceedingly dilute 



1 Ray-Lankester, Quarterly Journ. of Mic. Sc. 1O., N.S., 402 (1870). 



2 E. A. Menzies, Journ. of Physiol 17. 402 (1895). 



3 E. Ziemke and Franz Miiller, Arch. f. (Anat. u.) Physiol. 1901, Suppl. p. 177. 



4 In this way oxyhfemoglobin may readily be demonstrated. 



