DIPHTHERIA ANTITOXIN 279 



days old has been advocated, or of acid beef-broth in which 

 B. coli has been grown for twenty-four hours, in order 

 to eliminate the glucose (p. 27). L. Martin makes use of 

 " peptone " prepared by the auto-digestion of a pig's 

 stomach with dilute hydrochloric acid. The cultures are 

 then filtered through a Berkefeld or Pasteur-Chamberland 

 filter to remove the bacilli. The filtrate is germ-free and 

 very toxic, and a little carbolic acid may be added to 

 preserve it. In New York 10 per cent, of a 5 per cent, 

 solution of carbolic acid is added to the culture, the bacilli 

 are allowed to deposit by standing for forty-eight hours, 

 and the culture is filtered through paper ; in this way 

 filtration through a filter-candle is dispensed with. Less 

 than O'Ol c.c. of the toxin should kill a 250-grm. guinea- 

 pig in three to four days. Selected horses which have been 

 tested with mallein and tuberculin, and kept under obser- 

 vation for some time to ensure that they are healthy, are 

 then inoculated with this filtrate, commencing with a dose 

 of O01 to Ol c.c., according to the toxicity of the toxin, 

 or 20 c.c. of the toxin together with 10,000 units of anti- 

 toxin may be given for the first three doses. Individual 

 horses vary very much in their susceptibility to the toxin, 

 so that care has to be exercised with the first injections. 

 The injections are given subcutaneously over the shoulder, 

 and produce a local swelling and some rise of temperature 

 and general disturbance, lasting two or three days. When 

 this has passed away the inoculation is repeated, a larger 

 dose being administered provided the reaction due to the 

 former one was not too severe. The treatment is con- 

 tinued for five to six months, the dose of toxin administered 

 being gradually increased until it may attain 500 c.c. or 

 more. Cartwright-Wood found that by growing virulent 

 diphtheria bacilli for three or four weeks in ordinary 

 peptone broth, with the addition of 10 or 20 per cent, of 

 blood- serum or plasma, subjecting the culture to a tern- 



