THE BACILLUS OF TETANUS. 389 



ing to a 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 



