THE BACILLUS OF TETANUS. 389 
ing toa platinum needle—of an old culture is often 
sufficient to kill very susceptible animals like mice and 
guinea-pigs. Other animals require a larger amount. 
Birds are but little susceptible, and fowls scarcely at 
all. It is a remarkable fact that an amount of toxin 
-sufficient to kill a hen would suffice to kill 500 horses. 
On the inoculation of less than a fatal dose in test- 
animals a local tetanus may be produced, which lasts 
for days and weeks and then ends in recovery. On 
killing the animal there is found at autopsy, just at the 
point of inoculation, a hemorrhagic spot, and no changes 
here or in the interior organs other than these. A few 
tetanus bacilli may be detected locally with great diffi- 
culty, often none at all; possibly a few may be found 
in the region of the lymphatic glands. From this 
scanty occurrence of bacilli the conclusion has been 
reached that the bacilli of tetanus, when inoculated in 
pure culture, do not multiply in the living body, but 
only produce lesions through the absorption of the 
poison which they produce at the point of infec- 
tion. These authors also found that pure cultures of . 
tetanus, after the germs had sporulated and the toxins 
had been destroyed by heat, could be injected into 
animals without producing tetanus. Even one or two 
millions of spores, if deprived of the toxins, proved 
harmless to guinea-pigs, and from 15 to 30 c.c. of 
broth cultures were harmless to rabbits. But if a cul- 
ture of non-pathogenic organisms was injected simul- 
taneously with the spores, or if there was an effu-. 
sion of blood at the point of injection, or if there was 
a previous bruising of the tissues, the animals surely 
died of tetanus. Even irritating foreign bodies were 
introduced along with the spores deprived of their 
