25 
upon individuals of the same species. The same quantity of poison 
per gram weight of a particular animal always produces similar 
results. 
In 1893 Wladimiroff ® conducted under Behring’s direction a series 
of experiments to determine the minimal fatal dose for various 
species of animals. Considering the susceptibility to tetanus toxine 
for mice as 1, we have the following results. The minimal fatal dose 
is calculated to the body weight: 
Animal species. 
Minimal fatal dose. 
Susceptibility. 
White mice 
1 : 500.000 
' 1 
0.1 
2 
Considerably less than 
About 
White rats . 
1 : 50,000 
Guinea pigs 
1 ; 1,000,000 
Rabbits . 
Greater than 1 : 24,000 
Goats.. 
1 : 250.000 
Expressed in figures of minimal lethal doses for the above-men- 
tioned animals we have the following: 
Animal species. 
Minimal fatal dose. 
Minimal fatal dose ex- 
pressed in minimal fatal 
dose for mice. 
White mice 
0.00004 
1 
White rats 
0.004 
100 
Guinea pigs 
0.0002 
5 
Young goats 
0.1 
25.000 
Medium size rabbits. . . . . . 
5.0 
125, 000 
According to Behring, 1 minimal lethal dose per mouse is equiva- 
lent to 12 for a horse, 6 for a guinea pig, h for a goat, for a rabbit, 
T^oVo for a goose, for a pigeon, and 3 for a chicken. That is, 
the horse is 12 times as susceptible as the mouse, and the mouse is 
30,000 times more susceptible than the chicken. 
Knorr ^ in his paper on the subject gives a scale of susceptibility to 
tetanus poison. He finds the horse to be the most susceptible 
animal. If we take the dose that kills 1 gram of horse as unity, the 
amounts of poison required by the following animals is as follows: 
1 gram of guinea pig 
1 gram of goat 
1 gram of mouse . . . . 
1 gram of rabbit 
1 gram of hen 
2 times as much 
4 times as much 
13 times as much 
2,000 times as much 
200,000 times as much 
o Wladimiroff, A.; Ueber die Antitoxinerzeugende und immunisirende Wirkung 
des Tetanusgiftes bei Thieren. Zeit. f. Hyg., vol. 15, 1893, pp. 405-422. 
^ Knorr; “Das Tetanusgift und seine Beziehg. zum tier. Organismus,” Miinch. 
med. Woch., 1898, 321, 362. 
