332 HAND-BOOK OF PHYSIOLOGY. 



6 -^11 ^2 / C 1 TT O ) 



Leucin, or amido-caproic acid, [-ON, or -^-j^ 1 V- 



H ) 2 



occurs normally in many organs of the body and is a product of the pan- 

 creatic digestion of proteids. It is present in the urine in certain diseases 

 of the liver in which there is loss of substance, especially in acute yellow 

 atrophy. It occurs in circular oily discs or crystallizes in plates, and can 

 be prepared either by boiling horn shavings, or any of the gelatins, with 

 sulphuric acid, or out of the products of pancreatic digestion, 



2 H 3 2 } 

 Sarcosin may be considered as methyl glycin, CH 3 > 1ST. It is a 



H ) 

 constituent of kreatin, but has never been found free in the human body. 



Neurin (C 6 H 13 NO), is an unstable body, which has been found in 

 ox and pig'*s gall. 



0, H & ) 



Taurin, C 2 H 7 NS0 3 or S0 2 HO > N; or amido-isethionic acid, is a con- 

 EC ; 



stituent of the bile acid, taurocholic acid, and is found also in traces in 

 the muscles and lungs. See above. 



Cystin, C 3 H 7 NS0 2 occurs in a rare form of urinary calculus, which 

 is only formed in a urine of neutral reaction. It can be crystallized in 

 hexagonal laminae of pale yellow color, becoming greenish on exposure 

 to light. 



C 9 H 9 N0 3 ,orC 2 H 3 OJ 



Hippuric Acid, C 7 H 5 V N, or benzolglycin, a normal 



H ) 



constituent of human urine, the quantity excreted being increased by a 

 vegetable diet, and therefore it is present in greater amount in the urine 

 of herbivora. It may be decomposed by acids into glycin and benzoic 

 acid. It crystallizes in semi-transparent rhombic prisms, almost insoluble 

 in cold water, soluble in boiling water. (See also p. 361, Vol. I.) 



Tyrosin, C 9 H n N0 3 , is found, generally together with leucin, in 

 certain glands, e.g., pancreas and spleen; and chiefly in the products of 

 pancreatic digestion or of the putrefaction of proteids. It is found in 

 the urine in some diseases of the liver, especially acute yellow atrophy. 

 It crystallizes in fine needles, which collect into feathery masses. It gives 

 the proteid test with Millon's reagent, and heated with strong sulphuric 

 acid, on the addition of ferric chloride gives a violet color. 



Lecithin, C 42 H 84 P N0 9 , is a phosphoretted fatty body, which has 

 been found mixed with cerebrin, and oleophosphoric acid in the brain. 

 It is also found in blood, bile and serous fluids, and in larger quantities in 

 nerves, pus, yelk of egg, semen, and white blood-corpuscles. On boiling 

 with acids it yields cholin, glycero-phosphoric acid, palmic and oleic acids. 



Cerebrin, C 1? H 33 N0 3 , is found in nerves, pus-corpuscles, and in the 

 brain. Its chemical constitution is not known. It is a light amorphous 

 powder, tasteless and odorless. Swells up like starch when boiled with 

 water, and is converted by acids into a saccharine substance and other 

 bodies. The so-called Protagon is a mixture of lecithin and cerebrin. 



