FOOD POISONING 747 



sterile, a few bacterial spores escaping. If these consist of 

 strict aerobic species no harm results, but if anaerobic 

 forms survive poisonous products may be generated. 

 Generally, the development of anaerobes is accompanied 

 with gas formation, which tends to bulge the tins, giving 

 rise to the condition known'as " blown tin." the existence 

 of which acts as a danger signal. 



On the whole, evidence of the formation of poisonous 

 ptomaines in foodstuffs is not very conclusive, and this 

 form of food-poisoning must be of rare occurrence. 



Mussels from polluted layings occasionally give rise to 

 gastro-enteritis. This has been ascribed to the forma- 

 tion of a ptomaine, mytilotoxin, by the action of putrefac- 

 tive bacteria. 



In the United States outbreaks of food-poisoning in 

 connection with milk, cheese and ice-creams have been 

 recorded. Vaughan determined that the poisonous 

 property is due to the formation of tyrotoxicon, a benzene 

 derivative. The mode of its formation is unknown. 



Botulism is another form of food intoxication, caused 

 by the consumption of food containing the toxin of 

 B. boiulinus, an anaerobic bacillus which has. been de- 

 scribed at p. 524. No instance of botulism seems to have 

 been recorded in this country, but it occasionally occurs 

 on the Continent and in the United States in connection 

 with animal and vegetable products, preserved or tinned, 

 such as ham, sausage, pickled mackerel, bean salad and 

 canned beans, olives, 1 clam broth and meats. li has 

 also been met with in connection with fodder causing 

 poisoning of horses. 2 It was at one time supposed that 

 B. botulinus is a normal inhabitant of the hog's intestine, 

 but Dickson examined the intestine of 250 hogs and failed 



1 A characteristic and exhaustively investigated outbreak. See Public 

 Health Reps., U.S.A. Public Health Service, 1919, vol. 34, No. 51. 



2 Graham and Brueckner, Journ. of Bacteriology, 1919, vol. iv, p. 1. 



