APP.] CHEMICAL BASIS OF THE ANIMAL BODY. 757 



thyroid, salivary glands, liver, &c., and is one of the products of the 

 tryptic (pancreatic) digestion of proteids; in acute atrophy of the liver 

 it is present in the urine in large quantity, in company with tyrosin. 



As usually obtained in an impure form it crystallises in rounded 

 lumps which are often collected together and sometimes exhibit radiating 

 striation. When pure, it forms very thin, white, glittering flat crystals. 

 These are easily soluble in hot water, less so in cold water and alcohol, 

 insoluble in aether. They feel oily to the touch, and are without smell 

 and taste. Acids and alkalis dissolve them readily, and crystallisable 

 compounds are formed. 



Carefully heated to 170 C. it sublimes, but at a higher temperature is decom- 

 posed, yielding amylamin, carbonic anhydride and ammonia. In the presence of 

 putrefying animal matter it splits up into valeric acid and ammonia. 



Leucin is amido-caproic acid, and may be represented thus : 



Preparation. From horn shavings by boiling with sulphuric acid, 

 neutralising with baryta and separating from tyrosin by successive crys- 

 tallisation. See also Kiihne 1 , who prepares it by the action of pancreatic 

 ferment (trypsin) on proteids. 



Scherer has given the following test for leucin. The suspected sub- 

 stance is evaporated carefully to dryness with nitric acid ; the residue, 

 if it is leucin, will be almost transparent and turn yellow or brown on 

 the addition of caustic soda. If this be again very carefully concen- 

 trated with the alkali an oily drop is obtained, which is quite character- 

 istic of this substance. Leucin if not too impure, may be easily recog- 

 nized by its subliming on being heated; a characteristic odour of 

 amylamin is at the same time evolved 



Asparagine. C 4 H 8 N 2 O 3 . 



Is not found as a constituent of the animal body but appears- to be 

 formed by the decomposition of proteids, notably during the germinative 

 changes of the proteids in leguminous seeds 2 . It is a crystalline body, 

 and when boiled with acids or alkalis is readily converted into aspartic 

 acid. 



Aspartic (or asparaginic) acid. C 4 H 7 NO 4 . 



This acid has been obtained in small quantities among the products 

 of the pancreatic digestion of fibrin 3 and vegetable glutin 4 , although not 



1 Virchow's Archiv, Bd. 39, S. 130. 

 8 Landwirthsch. Versuchs Stationen. Bd. xvm. 1. 



3 Kadzieje-wski u. Salkowski, Ber. d. deutsch. cTiem. GeselL Jahrg. vn. (1874), 

 S. 1050. 



* V. Kuieriem, Zeitscli.f. Bio!. BJ. xi. (1875), S. 198. 



