120 THE BLOOD AND ITS CIRCULATION. 



lost its oxygen, as well as solutions of hemoglobuline which 

 have been deoxidized by any reducing agent, present a differ- 

 ent spectrum : the interval which separates the two bands is 

 darkened, or, in other words, the two black bands fuse into 

 one (reduction band of Stokes) (Fig. 35, E). At the same 

 time the shading which covers the most refrangible part is 

 withdrawn towards the violet, so that there is more transpa- 

 rency to the blue rays. 



There is thus a spectrum of oxygenated blood and of 

 deoxidized blood, of oxygenated hemoglobuline and of 

 reduced hemoglobuline. 



Claude Bernard and Hoppe Seyler demonstrated, at about 

 the same time, that oxide of carbon drives the oxygen from 

 the blood and takes its place, entering into combination with 

 hemoglobuline. This combination gives a spectrum (spec- 

 trum of oxycarbonated blood, very similar to that of the 

 oxygenated blood, with the exception of the two black 

 bands being slightly displaced towards the right. The prin 

 cipal feature in this spectrum is that the action of reduc- 

 ing elements produces no change in it ; in other words, the 

 spectrum of oxycarbonated hemoglobuline does not furnish, 

 like that of oxygenated hemoglobuline, Stokes's band of 

 reduction. The importance of these discoveries and of their 

 application is evident in the case, for instance, of a person 

 suffocated either by the fumes of charcoal or the oxide of 

 carbon. It is also important to notice that these distinguish- 

 ing bands can be obtained by washing with water old blood- 

 stains upon iron, wood, linen, etc., even where the blood is 

 already decomposed and putrid. Valentin has proved satis- 

 factorily the presence of blood upon a board taken from a 

 dissecting table, which had lain unused in a damp place for 

 three years, and also upon a rusty butcher's hook, which had 

 been long tkrown aside. Numerous attempts have been 

 made in vain (Kitter) to discover any coloring matter, of 

 which the spectrum could possibly be mistaken for that of 

 the blood, or which could, by means of the agents of reduc- 

 tion, show any thing analogous to the band of Stokes. 



This method of research is beyond almost every thing that 

 could be desired on the score of minuteness ; for Valentin 

 has discovered indisputable traces of the blood spectrum in 

 a solution containing only seven-thousandths of blood in a 

 thin layer of fifteen millimetres. 



By successive study of the spectrum of oxygenated and 

 deoxygenated blood, of oxygenated and reduced hempglob- 



