832 APPENDIX. 



ably identical with stercobilin, which is found in the faeces. Uroerytlirin 

 is one of the coloring matters of the urine. It is orange red and con- 

 tains iron, as is also Clioletelin 



Melanin is a dark brown or black pigment which occurs especially in 

 epidermal tissues, where it is associated with keratin. It is found in the 

 lungs, bronchial glands, hair, choroid, skin of negroes, etc. ; also in the 

 urine and in melanotic diseases, e.g., sarcoma. It is a transformation 

 product of proteids, to which it is closely related, and can be made arti- 

 ficially by boiling proteid with sulphuric acid. It contains C, H, 0, N, S, 

 and (rarely) Fe 



Lipochromes are pigments, usually yellow or yellowish-red, which are 

 associated with fat, being almost always present in adipose tissue Lit- 

 tle is known about them, but they are thought to consist only of C, H, 

 and 0. 



Hc&matin has been fully treated of, p. 1(52 ft xeq. 



Indican or Potassium Indoxyl sulphate,, (.^ H r XKSO ( , is found in the 

 urine and is derived from proteid putrefaction in the intestines. It is 

 colorless. 



Indiyu or Indigo-blue, C IO H 10 N., O.,, is formed from iudican. It is 

 usually found free in small amounts in decomposing urine, where it may 

 give a bluish color to the- sediment; in very rare instances it makes the 

 whole urine blur. 



Lndol, C M H. N, belongs to the aromatic series and is a product of 

 proteid putrefaction in the intestine. It is found in the fueces and helps 

 cause their odor. When absorbed, it is excreted in the urine as potas- 

 sium indoxyl sulphate (indican). 



Skatol, C 9 H y N, is also one of the aromatic series, a product of pro- 

 teid putrefaction in the intestines. It is found in the faeces and contrib- 

 utes to their odor. When absorbed, it is excreted in the urine as sodium 

 or potassium skatoxyl sulphate. Both indol and skatol are crystalline 

 and volatile. 



Nitrogenous Bodies of Uncertain Nature. 



Ferments are bodies which possess the property of exciting chemical 

 changes in matter with which they come in contact. They are at present 

 divided into two classes, called (1) organized, and (2) unorganized or 

 soluble. 



(1.) Of the organized, yeast may be taken as an example. Its activ- 

 ity depends upon the vitality of the yeast cell, and disappears as soon as 

 the cell dies, neither can any substance be obtained from the yeast by 

 means of precipitation with alcohol or in any other way which has the 



