20 BACTERIAL PROTEIJ)S. 



The purified pyogenetic agent obtained from the pneu- 

 monia bacillus of FJUEDKANDER was found by I>i c HNER 

 to give the following reactions: It is soluble in water and 

 the concentrated mineral acids, very soluble in dilute alka- 

 lies, from which it is precipitated on the addition of an acid. 

 From its aqueous solution, it is not precipitated by heat, 

 nor by saturation with sodium chloride, but is precipitated 

 by magnesium sulphate, copper sulphate, platinum chloride, 

 gold chloride, lead salts, picric acid, tannic acid, and abso- 

 lute alcohol. It gives the xanthoproteid, Millon, and 

 biuret reactions. 



The Bacterial Proteids. BRIEGER and FRANKEL ob- 

 tained the proteid poison of diphtheria by precipitating 

 the filtrate from a Chamberland filter after concentration 

 to one-third its volume at 30, with absolute alcohol after 

 feebly acidifying with acetic acid. The precipitate was puri- 

 fied by repeated solution in water and repreeipitation with 

 alcohol. Dried in a vacuum at 40, it forms a snow-white, 

 amorphous, very light mass. From its aqueous solution it 

 is not precipitated by heat or dilute nitric acid, singly or 

 combined, nor by sodium sulphate, sodium chloride, mag- 

 nesium sulphate, or lead salts. It is precipitated by car- 

 bonic acid (to saturation), concentrated mineral acids, 

 potassium ferrocyanide and acetic acid, phenol, organic 

 acids (soluble in excess), copper sulphate, silver nitrate, 

 and mercuric chloride. The so-called alkaloidal reagents 

 phosphomolybdic acid, potassio-mecuric iodide, potass io- 

 bismuthic iodide, platinum chloride, gold chloride, and 

 picric acid also cause precipitation. The xanthoproteid, 

 Millon, and biuret reactions give positive results. An ulti- 

 mate analysis furnishes the following figures computed 

 from the ash-free substance : C 45.35, H 7 J3, N 16.33, S 

 1.39, O 29.80. From these facts BRIEGER and FRANK KL 

 conclude that this substance is allied to serum-albumin. 

 Their bouillon cultures contain serum-albumin, and they 

 suppose that the bacteria convert this into the poison by 

 causing a rearrangement in the atoms; but the same poison 

 was formed when nutrient solutions containing no proteid 



