TETANUS TOXINE. 109 



organic substance i.e., only a very small trace of pure toxine. 

 The organic matter required for a mouse was only 0*000000025 

 grm. According to BRIEGER and COHN (loc. cit.}, the lethal dose 

 of a far from pure toxine was about 0-0000005 grm. for a mouse, 

 and '00023 grm. for a man, but occasionally still more poisonous 

 preparations have been obtained. The individual variations are 

 also very great. According to BEHRING and KNORR, the certain 

 lethal dose for a mouse is about six times as great as that which 

 is just below that required to kill. Still greater, however, are 

 the variations in the toxicity due to the susceptibility of the 

 different species of animals. 



KNORR, 1 in his paper on the subject, gives a scale of suscepti- 

 bility to tetanus poison. He finds the horse to be the most 

 susceptible animal. If we take the dose that kills 1 grm. of 

 horse as unity, the amounts of poison required by the following 

 animals are as follows : 



1 grm 

 1 , 



1 ', 



1 



of guinea-pig, 

 goat, . 

 mouse, 

 rabbit, 

 hen, . 



2 times as much. 

 4 ,, 



13 



2,000 

 200,000 



BEHRING 2 gives the following scale for fresh poisons, which 

 show no difference between the direct and indirect toxic value 

 (equivalent, poisons) : 



One lethal dose for 1 grm. of mouse ( + Ms) kills 



12 grms. of horse. 

 6 guinea-pig. 

 0'2 grm. of goat. 

 Titf rabbit. 



The numbers thus agree fairly well. In the case of old 

 poisons, in which, according to BEHRING, the direct toxic value 

 ( + Ms) is much smaller than the indirect value ( + ms) i.e., the 

 relative value for the quantity which, after neutralisation of T^OQ- 

 an ti toxine unit, is still lethal (xoW an ti toxine units = 40,000 

 Ms), are quite irregular. In like manner the ratios between the 

 smallest dose that causes illness and the smallest fatal dose vary 

 very greatly with the species of animal. 



1 Knorr, " Das Tetanusgift und seine Beziehg. zum tier. Organismus," 

 Munch, med. Woch., 1898, 321, 362. 



2 Behring, "Ueber Tetanusgiftmodifikationen," Fortschr. d. Med., 

 xvii., 501, 1899. 



