38 MEAT EXTRACTS. 



mins and gelatin, as well as the albumin and gelatin peptones, are 

 precipitated by this reagent. In an excess of the reagent the albumin 

 peptones are soluble, while the gelatin peptones are not. 



A 10 per cent solution of trichloracetic acid was prepared and its 

 action tested on the following nitrogenous bodies: (1) Gelatin; (2) 

 a mixture of gelatoses and gelatin peptones; (3) Witte's peptone 

 (albumose and peptone preparation) ; (4) meat extract. The results 

 of the test are as follows: 



In the case of the gelatin sample ten drops of the reagent gave a 

 slight precipitate, while the other three nitrogenous substances exam- 

 ined gave no precipitate. An excess of the reagent gave a heavy 

 white precipitate with gelatin and Witte's peptone, a smaller pre- 

 cipitate in the case of the meat extract (the reaction being obscured 

 by the dark color of the solution), while the gelatose solution showed 

 only a slight turbidity. 



It is evident from these results that trichloracetic acid does not pre- 

 cipitate the gelatoses, neither when a small amount nor when an 

 excess of the reagent is used. The gelatoses are precipitated by the 

 tannin salt reagent and it is possible that a method for estimating the 

 gelatoses may be worked out on the basis of the trichloracetic acid 



reagent. 



Total Meat Bases. 



The meat bases contain from 40 to 60 per cent of the nitrogen in 

 solid meat extracts, as is shown in Table III. In one of the poorest 

 extracts examined, but 3.82 per cent of the total nitrogen is present 

 in this form. 



The meat bases are divided into two general classes, the mono- and 

 the di-amido acids. By the method of analysis employed, the meat 

 bases are found in the filtrate from the tannin-salt precipitate. 

 Some of the meat bases, for example, kreatin and kreatinin, and the 

 hexon and xanthin bases are well defined chemical bodies that have 

 been isolated and analyzed, but a considerable number of the nitro- 

 genous bodies classed as total meat bases are of unknown constitution 

 and are classed as undetermined nitrogenous matter. 



Many new bodies have been found in meat extract in recent years. 

 Kutscher a has recently found the following nitrogenous bodies: 

 Ignotin, methyl guanidin, carnomuscarin, neosin, novain, and oblitin. 

 Krimberg 6 has demonstrated the presence of carnosin, carnatin, 

 and methyl guanidin in flesh. Micko c applied Fischer's ester method 

 to Liebig's extract and found alanin, leucin, and glycocoll in abund- 

 ance. No amido valeric acid was found, and most of the amido acids 

 were left in a sirupy mass. 



«Zts. Nahr. Genussm., 1905, JO: 528. 

 bZts. physiol. Chem., 1906, 48:412. 

 c Zts. Nahr. Genussm., 1902, 5:193. 



