BACTERIAL CELLULAR SUBSTANCE 79 



tyrosin as 235; Cohn as 295; while Fischer says that with 

 rapid heating the corrected point is 314 to 318. 



"The tyrosin obtained gives a Hofmann test with 

 Millon's reagent. It gives Scherer's test with nitric acid 

 and sodium hydrate on platinum foil, and also a beautiful 

 Piria test with sulphuric acid, then barium carbonate and 

 ferric chloride, which test is characteristic for tyrosin. 



"The leucin crystallized in the characteristic knobs or 

 balls. As it became purer it crystallized more and more in 

 shining, white, very thin plates, sometimes in radial groups, 

 sometimes not. The crystals were finally obtained with a 

 practically constant melting-point, 262 to 263 or corrected, 

 268.5 to 269.6. The pure laboratory leucin (Kahlbaum) 

 melted at the same point. Schwanert, Hammersten, and 

 others give the melting-point for active leucin as 170; 

 that for the inactive form is given as 270. Fischer says 

 the melting-point is 293 to 295 (corrected) if heated 

 quickly in a closed tube. Cohn gives 275 to 276. The 

 leucin obtained melted with darkening and decomposition. 

 With careful heating in an open tube it sublimed with 

 the characteristic white, woolly deposit. It also responded 

 to Scherer's test on platinum foil with nitric acid and 

 sodium hydrate, which test Hammersten says is charac- 

 teristic for leucin." 



Agnew 1 has made the following contribution to the 

 mono-amino-acid content of the cellular proteins of the 

 colon and tubercle bacilli. 



The material used in this research consisted of the cellular 

 substance of the bacteria. Growths from massive cultures 

 were placed in large Soxhlets and extracted for three days 

 with absolute alcohol and for the same time with ether. 

 The protein bacterial substance thus freed from everything 

 soluble in alcohol and ether was ground into a powder and 

 passed through a fine-meshed sieve. For the preparation 

 of the amino-acids Fischer's method slightly modified was 

 employed. The cellular protein was boiled with three and 



1 Unpublished research. 



