COLORING ORGANIC SUBSTANCES. 



103 



precise action is, can still be only conjectured. And yet the idea 

 that the hasmatine or the corpuscles are alone or mainly acted upon 

 by the inspired oxygen seems to be weakened by the observations 

 of Hannover, which show that chlorotic persons, whose blood is 

 poor in red corpuscles, exhale as much carbonic acid as healthy 

 persons. (<f- 1 ' 1 1) 



The probability that haematine is finally transformed into haema- 

 toidine has already been shown. From it, also, melanine is proba- 

 bly derived. 



In connection with haeraatine should be mentioned the red crys- 

 tals first observed and obtained from the red blood-corpuscles by 

 Funke, and which Lehmann terms the albuminous crystalline sub- 

 stance of the blood. Fig. 44 shows the form of these crystals in 



Fig. 44. 



Fig. 45. 





Crystals of human venous blood. 



Crystals from blood of the guinea-pig. 



human blood, and Fig. 45 those obtained from the corpuscles of the 

 guinea-pig. They are not formed till after the corpuscles burst. 



The relation of these crystals to haematine is, doubtless, important; 

 they being the substance from whose metamorphosis haematine is 

 probably produced. 



4. Melanine. 



This is the dark pigment found on the choroid coat of the eye, 

 and in pigment-cells generally. The melanotic deposit, so called, 

 also probably consists of it. Its formula is not yet ascertained. It 

 is certain that the pigment often deposited in the lungs as a morbid 



