BACILLUS BOTULINUS 477 



in the zone of fluidification, show constant motion. The appearance of 

 the surface colonies on glucose-gelatin plates is regarded by the discov- 

 erer as diagnostically characteristic. 



In gliicose broth there is general clouding and large quantities of 

 gas are formed. At 35° C. and over, the gas formation ceases after four 

 or five days, the broth becoming clear with a yellowish-white flocculent 

 sediment. At lower temperatures this does not occur. 



Milk is not coagulated and disaccharids and polysaccharids are not 

 fermented. 



The gas formed in cultures consists chiefly of hydrogen and methane. 

 All cultures have a sour odor, like butyric acid, but this is not so offensive 

 as that of some of the other anaerobic organisms. 



The bacillus lives longest in gelatin cultures, but even upon these, 

 transplantations should be done every four to six weeks, since the 

 spores of this bacillus show less viability and resistance than do those of 

 most spore-formers. 



Pathogenicity. — Botulism or allantiasis, as noticed in human beings, 

 is, as far as we know, always due to ingestion of infected meat, usually 

 of ham, canned meats, or sausages (botulus = sausage). Symptoms 

 appear only after a definite period of incubation which varies from 

 twenty-four to forty-eight hours. The first definite symptoms are 

 chilliness, trembling, and giddiness. These manifestations are soon 

 followed by headache, occasionally by vomiting. In contradistinction 

 to the meat poisonings caused by other microorganisms, those due to 

 Bacillus botulinus may show few or no symptoms directly referable to 

 the intestinal tract. The chief diagnostic characteristics of the disease 

 are a group of symptoms referable to toxic interference with the cranial 

 nerves. Loss of accommodation, dilated pupils, ptosis, aphonia, and 

 dysphagia may occur. Fever is usually absent. Consciousness is rarely 

 lost. The characteristic symptoms may be produced in various animals 

 by injection of living cultures or culture filtrates, i.e., toxins. The most 

 susceptible animals are guinea-pigs. These may be killed by the injec- 

 tion of minute quantities of bouillon cultures or of toxin. Preceding 

 death, which occurs within twenty-four to thirty-six hours, there may 

 be general motor paralysis, dyspnea, and hypersecretion of mucus from 

 nose and mouth. Guinea-pigs may be infected per os as well as by 

 hypodermic injections. Cats, mice, and monkeys are highly susceptible; 

 rabbits are less so, but still favorable subjects for experimental studies. 

 Birds, especially pigeons, are highly resistant, but react typically to 

 large doses. Autopsies upon man or animals dead of botulism show 

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