20 



MANUAL OF HISTOLOGY. 



of Hoppe, to which the statements made above in respect to blood- 

 crystals refer. 



A dilute solution of oxyhaemoglobin shows, as was discovered by Hoppe, 

 two broad bands of absorption between the lines D and E of the solar 

 spectrum (fig. 2, a) in the yellow and green part. Solutions of reduced 



Fig. 2. Appearances of solutions of haemoglobin in the spectroscope, a, oxyhoemoglobin and nitroxy- 

 haemoglobin ; 6, carbonic oxide haemoglobin ; c, reduced haemoglobin ; d, haematin in acid solution ; 

 e, haematin in alkaline solution ;/, reduced haematiu. Solar spectrum with Frauenhofer's lines. 



haemoglobin, on the other hand, have only one absorption band between 

 D and E (e), (Stokes). 



Reduction of oxyhaemoglobin takes place easily. It may be brought 

 about by the action of carbonic acid also. 



Reduced haemoglobin may also form crystals. They are of a deep 

 purple colour, and far more soluble than those of oxyhsemoglobin. 



The latter substance, in contact with carbonic oxide gas, parts with its 

 oxygen, and absorbs the last named compound. In this way a crystalline 

 compound of carbonicoxide with haemoglobin is produced (Hoppe). 



