BACILLUS BOTULINUS 249 



B. Tetani presents a drumstick appearance due to large terminal 

 spores ; in glucose stab cultures growth resembles an inverted tree. 



B. Welchii. One of the surest tests for differentiating B. 

 Welchii from the other anaerobes was devised by Welch and Mit- 

 tal. Bacilli are injected into the ear vein of a rabbit, which is 

 killed after a few minutes by a blow on the head. The body is 

 incubated and within twenty-four hours it becomes tensely dis- 

 tended with gas, and at autopsy gas bubbles are found in all the 

 organs. 



B. Edematis may be distinguished from B. Welchii by the fact 

 that it is motile and the lesions it produces are edematous rather 

 than emphysematous. 



B. Chauvei. Injection of pure cultures into rabbits is the 

 best means of differentiating B. chauvei from B. edematis and 

 B. welchii. Rabbits are immune to the former and susceptible 

 to the two latter organisms. 



BACILLUS BOTULINUS 



As already stated the term meat poisoning is applied to dif- 

 ferent conditions produced by different agents. The relation of 

 certain members of the colon-typhoid group to so-called ptomain 

 poisoning has already been noted. Another and totally different 

 type of food poisoning is due to the toxin generated by B. botulinus 

 during its growth on nitrogenous substances outside of the body. 

 The bacillus is a parasite and does not multiply within the body. 

 Fortunately it requires time for it to develop and produce its toxin, 

 and for this reason fresh foodstuffs are not apt to be dangerous so 

 far as botulism is concerned. Sausage, canned meat, and fish have 

 been found mainly responsible for the conveyance of the poison to 

 human beings. It is of singular importance that meat may con- 

 tain numbers of the bacilli and relatively large amounts of the 

 poison without any visible sign of decomposition. In 1896 van 

 Ermengen isolated B. botulismus from a sample of ham which 

 had been eaten raw and which had caused a number of cases of 

 poisoning, some of which had ended fatally. 



