BACTERIAL POISONS. 71 



65° C. for five minutes, direct sunlight for fifteen to eighteen 

 hours, weak acids and alkalies destroy the activity of a teta- 

 nus filtrate, and no means of precipitating the toxine without 

 at the same time partially or wholly removing its specific 

 properties at present exist. Attempts to isolate the 

 poison of tetanus have, however, been repeatedly made, 

 and the latest work in this direction is that of Brieger 

 and Georg Cohn. 1 Tetanus filtrates differ in virulence 

 according to the medium on which the bacillus is grown, 

 and a concentrated impure poison three times as powerful 

 as the direct poison used by Kitasato was obtained from a 

 medium of veal-bouillon containing 1 per cent, peptone 

 and "5 per cent. salt. The crude poison was precipitated 

 from the sterile filtrate by saturation with ammonium 

 sulphate. The precipitate floated on the surface, was 

 removed, allowed to drain on porous slabs and dried in 

 vacuo. The whole of the toxine was held in the pre- 

 cipitate, the remaining fluid being innocuous. Prepared 

 in this way the crude poison contained about 6 per 

 cent, of ammonium sulphate and other salts, proteids 

 and peptone, amido-acids, and volatile odorous products, 

 and its activity was neither destroyed by a tempera- 

 ture of 6o° C. nor by the addition of absolute alcohol 

 with 1 per cent, of corrosive sublimate. The proteid 

 impurities were removed with basic lead acetate and 

 a trace of ammonia, and the remainder by dialysis. 

 Evaporation of the dialysed fluid in vacuo at 20" C. 

 yielded the tetanus toxine in the form of faint yellow trans- 

 parent scales, which are soluble in water and lsevo- 

 rotatory. It contains but little ash and does not respond 

 to many of the common J:ests for proteids. Calcium 

 phosphate, used with such success by Yersin and Roux 

 in their researches on the poison of diphtheria, does 

 not, as is the case with enzymes, remove the toxine 

 from its solutions. The poison is free from phos- 

 phorus. Although in yielding the biuret reaction, 

 and a precipitate on the addition of ammonium sul- 



1 Brieger and Georg Cohn, Zeitschrift fur Hygiene, 1893. 



