410 PATHOGENIC BACTERIA. 



when it is present in quantities not exceeding 0.2 per 

 cent, in peptone bouillon freed from fermentable acid- 

 producing substances (muscle-sugar) it leads to the maxi- 

 mum accumulation of toxin by utilizing the available 

 peptones to the best advantage. 



Martin 1 believes that it is essential to provide a stand- 

 ard peptone for use in cultures intended to be highly toxic, 

 and has recommended for this purpose what he calls a 

 "bouillon de panse," which is prepared by adding to 

 200 grams of finely chopped hogs' stomachs, 10 c.cm. of 

 pure hydrochloric acid and 1000 c. cm. of water. The mixt- 

 ure is kept at 50 C. for from twelve to twenty-four hours, 

 during which time the proteids of the stomach are con- 

 verted into peptones. The mixture is now heated to ioo° 

 C, to destroy the excess of pepsin, and passed through a 

 cloth. The liquid is warmed again to 8o° C. and alka- 

 linized, then filtered through paper. After this it is to be 

 elevated to 120 C, filtered again through paper, dis- 

 pensed in flasks, and sterilized in the autoclave. The 

 dipththeria bacillus grows abundantly in the medium, 

 without the production of any acid, and produces toxin 

 of which T ^ ¥ c.cm. killed a 500-gram guinea-pig. The 

 mixture can be used as thus prepared, or can be mixed 

 with an equal volume of veal infusion. 



I have tried this method, but have not found it any 

 better, if as good, as the ordinary bouillon made accord- 

 ing to the suggestions of Park and Williams. 



The Immunisation of the Animal. — The animals chosen 

 to furnish the antitoxic serum should be animals which 

 present a distinct natural immunity to ordinary doses of 

 the toxin, and should be sufficiently large to furnish large 

 quantities of the finished serum. Behring originally 

 employed dogs and sheep ; Arouson at first preferred the 

 goat ; but Roux introduced the horse, which is more easi- 

 ly immunized than the other animals mentioned, and, 

 being large enough to furnish a considerable quantity of 

 serum, recommends itself strongly for the purpose. 



1 Ann. de P Inst. Pasteur, Jan. 25, 1898, vol. xii., No. 1. 



