THE BLOOD. 



119 



analysis. Hoppe Seyler (1862) and Valentin, in Germany ; 

 Stokes and Sorby, in England ; Bert, Claude Bernard, Be- 

 noit, 1 and Fumouze, 2 in France, have, by applying to the 

 study of the blood the means of analysis discovered by 

 Kirchoff and Bunsen, shown that when a large solution of 

 arterial blood is examined through a prism (spectroscope) 

 by the light of the sun or of a lamp, we find, instead of the 



Red. 



Yellow. 



Green. 



Blue. 



Violet. 



B C 



I 



Fig. 36. Absorption of certain parts of the spectrum by solutions of blood.* 



ordinary luminous spectrum, one crossed by broad dark 

 bands (placed as in Fig.- 35) ; this is called the absorption 

 spectrum of the blood: it is essentially characterized by 

 two dark bands in the yellow and green, and also by the 

 almost entire extinction of the most refrangible rays, begin- 

 ning at the blue or the indigo (Fig. 35, C). 



It is remarkable that the venous blood, and that which has 



1 R. Benoit, " Etudes Spectroscopiques sur le Sang." These, 

 Montpelier, 1869. 



2 Fumouze, " Les Spectres d' Absorption du Sang." Paris, 

 1871, in 4to. 



* A, Fraunhof er lines. B, Oxygenated arterial blood (two bands of absorption 

 between the lines D and E of Fraunhof er, that is, in the yellow of the spectrum). 



C, Arterial blood in a more concentrated state of solution (absorption of all 

 the rays beginning at F, that is, the blue). 



Dj Solution still more concentrated. E, Venous blood, reduced blood; ab- 

 sorption band near the line D of Fraunhofer (that is, in the yellow). (Paul 

 Bert.) 



