748 A MANUAL OF BACTERIOLOGY 



to find it. Burke 1 examined a variety of substances 

 leaves, hay, vegetables and fruits, manure, soil, insects, 

 snails, material from birds and isolated the organism 

 on seven occasions from mouldy hay, mouldy and damaged 

 cherries, beans, spiders on beans, and the manure 

 from a hog which had recovered from botulism. It is 

 not necessarily associated with active decay, but may 

 be present in blemishes on otherwise sound fruit and 

 vegetables. 



B. botulinus, when consumed apart from its toxin, 

 produces no effect, so that botulism is caused by the 

 ingestion of food in which the toxin has been formed as a 

 result of the development of B. botulinus in it. The toxin 

 is destroyed by heating to 70 C., so that well-cooked 

 food would be harmless, even though B. botulinus might 

 have been growing in it. Symptoms usually appear 

 twelve to twenty-four hours after the consumption of 

 the infected food and are almost entirely referable to 

 lesions of the central nervous system thirst, dysphagia, 

 amaurosis, paralysis of accommodation, ophthalmoplegia, 

 mydriasis, etc. Vomiting and diarrhoea are frequently 

 absent, but if present are slight and transitory. Fatal 

 cases show increasing respiratory paralysis and cardiac 

 failure ; the case mortality may be 30 per cent., 50 per 

 cent., or higher. 



Ergotism is another example of food intoxication, due 

 to the consumption of rye which has been attacked by 

 the ergot fungus, Claviceps pur pur ea. 



2. Food-poisoning associated with infection. While 

 infection associated with food may be due to the typhoid 

 and tubercle bacilli, cholera vibrio and many other 

 organisms, common usage restricts this form of food- 

 poisoning to infections with organisms belonging to the 



1 Journ. of Bacteriology, 1919, vol. iv, p. 541. 



