52 



PRACTICAL PHYSIOLOGY. 



[VI. 



alkali-hsematin, Stokes's reduced hgematin or hsemochromogen, 



and observe its spectrum ; two absorption-bands between D and 

 E, as with HbO., and HbCC), but they are nearer the 

 violet end. The first band to tlie violet side of the D 

 line is well defined, while the second band, still nearer 

 the violet end (in fact, it nearly coincides with the 

 E line), is less defined. They disappear on shaking 

 vigorously with air, and reappear on standing, pro- 

 vided sufficient ammonimn sulphide be added. 



HaBmochromogen and Hsematin. — Seal up in a glass tube 

 a solution of oxy-h:Temoglobin with caustic soda. Hoppe-Seyler 

 recommends the following method but it is unnecessary. Ar- 



KEO range a tube as in fig, 29. Place some hitmoglobin solution 

 in A, and into a narrower cup-shaped glass tube (B), with a 

 long stem place some NaHO, and place B inside A, as shown 

 in the figure. Draw out the end of tube A in a gas-flame, and 

 seal it in the flame. Mix the two solutions. At the end of 

 three weeks break ofl" the narrow end of the tube, and shed 

 the contents upon a white plate. The contents consist of red 



^ hitmochromogen, but the latter, as soon as it is exposed to 

 the air, becomes brown, and is converted into hsematin. 



16. VI. Methaemoglobin (fig. 30). 

 (a.) To a medium solution of oxy-hsemoglobin add 

 a few drops of a freshly-prepared strong solution of 

 ferricyanide of potassium (or a i per cent, solution of 

 potassic permanganate), warm gently, observe the 

 change of colour, and examine it with a spectroscope. 

 If the two bands of oxy-haemoglobin are still present, 

 Fig. 29. — Appara- allow it to stand for some time and examine 

 tus for making again. If they persist, carefully add more ferri- 



Hsemochromogen. & .* ,., ,,-^ , ' , i i- -».^ , 



cyanide until the two bands disappear. ^ote 

 one absorption-band in the red near C, nearly in the same posi- 

 tion, but nearer D than the band of acid haematin; the violet 

 end of the spectrum is much shaded. Three other bands are 



A a B C 



. 40 50 



mi 



I 



70 



Eb 



80 



iiiiliinliiiilijllllllil||nllljll[llll 



F 



9p , jqo u 



liiulmiliiii 



m^miL 



A 



Fig. 30. — Spectnim of Methiemoglobin in Acid and Nential Solutions. 



described, tw-o in the green, and one in the blue, especially in 

 dilute solutions. On adding ammonia to render the solution 

 alkahne, the band in the red disappears, and is replaced by a 

 faint band near D. 



J 



