PROTECTIVE INOCULATIONS. 3853 
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 (1898) 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 
avacuum. 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 forty-eight hours, after which 
it was dried in vacuo 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, 
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