PROTECTIVE INOCULATIONS. 353 



great and peculiar pathogenic power. The distinguished German 

 chemist and his associate have succeeded in isolating from tetanus 

 cultures a toxalbumin which is far more deadly than tetanin. 



Brieger and Cohn in more recent investigations (1893) relating to 

 the toxic products of the tetanus bacillus have arrived at the following 

 results : The cultures were made in veal bouillon containing one per 

 cent of peptone and one-fifth per cent of chloride of sodium. Large 

 quantities of the cultures in this medium were filtered through porce- 

 lain filters. The active substance was precipitated from the filtrate 

 by means of a saturated solution of ammonium sulphate. By adding 

 this salt in excess the precipitate is made to rise to the surface and is 

 skimmed off with a platinum spatula. The liquid is removed by plac- 

 ing this upon porous porcelain plates and the crude toxin is dried in 

 a vacuum. It still contains 6.5 per cent of ammonium sulphate. The 

 tetanus bouillon after filtration is said to be fatal to mice in the dose 

 of 0.00005 cubic centimetre. A litre of this bouillon gave about one 

 gramme of the dried precipitate, which produced characteristic te- 

 tanic symptoms and death when injected into mice in the dose of 

 0.0000001 gramme. Kitasato in his experiments had previously ob- 

 tained a tetanus bouillon which was five times as toxic as that used by 

 Brieger and Cohn in their experiments, and which killed mice in the 

 dose of 0.00001 cubic centimetre. The dried precipitate obtained by 

 Brieger and Cohn contained various impurities, including a certain 

 amount of ammonium sulphate, but was found to kill susceptible ani- 

 mals in the proportion of 0.0000066 gramme per kilogramme of body 

 weight. 



It was purified without loss of toxic power by placing it in a dialyzer 

 in running water for from twenty -four to f orb* -eight hours, after which 

 it was dried in vacua at 20 to 22 C. The purified toxin thus ob- 

 tained had a slightly yellowish color, and was in the form of trans- 

 parent scales, which were odorless, tasted like gum acacia, and were 

 easily soluble in water. The chemical reactions of this purified toxin, 

 according to Brieger and Cohn, show that it is not a true albuminous 

 body. When injected beneath the skin of a mouse weighing fifteen 

 grammes, in the dose of 0.00000005 gramme, it causes its death, and 

 one-fifth of this amount gave rise to tetanic symptoms from which the 

 animal recovered after a time. The lethal dose for a man weighing 

 seventy kilogrammes is estimated by the authors named to be 0.00023 

 gramme (0.23 milligramme). Comparing this with the most deadly 

 vegetable alkaloids known it is nearly six hundred times as potent as 

 atropine and one hundred and fifty times as potent as strychnine. 



Fermi and Pernossi (1894), as a result of an elaborate research, 

 23 



