212 PHYSIOLOGICAL CHEMISTRY. 



phenols and aromatic acids. Leucine and tyrosine are occa- 

 sionally found, but their presence is generally pathological, 

 if in quantity more than traces. 



Among products of distinctly pathological origin blood and 

 pus may be mentioned ; both yield albumin and the corpuscles 

 of each may frequently be recognized by the microscope. It 

 is also possible to recognize the coloring matter of the blood 

 by the spectroscope. It has been mentioned that cholalic acid, 

 a derivative of the two characteristic acids of the bile, may be 

 found with the fats of the feces. The bile acids themselves, 

 glycocholic and taurocholic, are also found; likewise the bile 

 pigments or their disintegration products. Most of the bile 

 coloring matters fail to be reabsorbed from the intestine into 

 which they are discharged and must be excreted therefore by 

 the feces and only in small part by the urine. 



