COLOBLNTG MATTERS. 93 



the circulating fluid, and relieves the general effects of the 

 deficiency of coloring matter; an effect which cannot be 

 produced by the most nutritious articles of food. Hematine 

 is probably destroyed in the organism, and furnishes material 

 for the formation of the other coloring matters. 



Melanine. This substance resembles hematine, contain- 

 ing, however, a smaller proportion of iron. It is of a brown- 

 ish color, and is found in all parts of the body where pigment 

 exists ; such as the choroid, iris, hair, or epidermis. It exists 

 in the form of granulations, either free or .enclosed in epithe- 

 lial cells. In all probability it is formed by a transformation 

 of'hematine. 



biliverdine. This is a greenish-yellow coloring matter 

 peculiar to the bile. Extracted from the bile, it is insoluble 

 in -water, but soluble in alcohol or ether. It contains iron in 

 nearly the same proportion as hematine. 



Biliverdine is formed from hematine, enters into the con- 

 stitution of the bile, is discharged into the small intestine, 

 and, after undergoing certain modifications, is discharged 

 from the body in the feces. 



Urrosacine. This is the principle which gives the amber 

 color to the urine. After extraction, it is insoluble in water, 

 but soluble in alcohol or ether. It exists in the urine in very 

 small quantity, and is formed in the kidney, in all probability 

 at the expense of the hematine. Urrosacine and biliverdine 

 are the two coloring matters discharged from the body. 



Summary. A review of the individual properties of the 

 organic nitrogenized principles shows great differences in their 

 physiological, and very slight differences in their purely 

 chemical characters. It is a fact too apparent to require 

 argument, that their chemical history is of little importance 

 compared to a study of their vital properties. In fact re- 

 searches into their ultimate composition, with the excep- 



