PROTECTIVE INOCULATIONS. 351 
at the seat of injury, in cases of tetanus in man, has now been 
demonstrated by numerous observers, there is no longer any ques- 
tion that tetanus must be included among the traumatic infectious 
diseases, and that the bacillus of Nicolaier and of Kitasato is the 
specific infectious agent. Kitasato’s experiments (1890) show that 
cultures of the tetanus bacillus which have been sterilized by fil- 
tration through porcelain produce the same symptoms, and death, in 
the animals mentioned, as result from inoculation with cultures con- 
taining the bacilius. It is evident, therefore, that death results from 
the action of a toxic substance produced by the bacillus. This is 
further shown by the fact that the bacillus itself cannot be obtained in 
cultures from the blood or organs of an animal which has succumbed 
to an experimental inoculation with an unfiltered culture; but the 
blood of an animal killed by such an inoculation contains the tetanus 
poison, and when injected into a mouse causes its death with tetanic 
symptoms. 
When a platinum needle is dipped into a pure culture of the teta- 
nus bacillus, and a mouse is inoculated with it subcutaneously, the 
animal invariably falls sick within twenty-four hours and dies of 
typical tetanus in two or three days. Rats, guinea-pigs, and rabbits 
are killed in the same way by somewhat larger quantities—0.3 to 0.5 
cubic centimetre (Kitasato). Pigeons are very slightly susceptible. 
The tetanic symptoms are first developed in the vicinity of the point 
of inoculation: if the animal is inoculated in the posterior portion of 
the body, the hind legs first show tetanic contraction; if in the fore- 
part of the body, the muscles of the neck are first affected. At the 
autopsy there is a certain amount of hyperemia at the point of inocu- 
lation, but no pus is formed; in inoculations with garden earth, or 
accidental inoculations in man, pus is commonly found in the vicinity 
of the inoculation wound. The various organs are normal in appear- 
ance. Kitasato says that he has not been able to demonstrate the 
presence of the bacillus or of spores in the spinal marrow, the nerves, 
muscles, spleen, liver, lungs, kidneys, or blood from the heart; nor 
has he been able to obtain cultures from the various organs. In mice 
which were inoculated at the root of the tail Kitasato was able to de- 
monstrate the presence of the bacilli at the point of inoculation by the 
microscopical examination of an excised piece of the tissues for eight 
to ten hours after the inoculation; later than this they were not found. 
In pus from the inoculation wounds of men and animals accidentally 
infected the bacilli are present, but the formation of spores does not 
always occur. According to Kitasato, the sooner death has occurred 
after accidental inoculation the less likely are spores to be found in 
