Parenteral introduction of amounts of the culture filtrate of Bacillus botulinus greatly in excess of the minimum lethal dose has been observed to cause the practically immediate death of mice. This result is due to the presence in the filtrates of a chemical poison possessing properties distinct from those of the contained botulinus toxin which itself acts only after a well defined period of incubation. This chemical poison is not neutralized by botulinus antitoxin; it is effective only when large amounts of the culture filtrate are given; it is thermostable, not being destroyed when heated in the autoclave in a sealed tube, though when it is heated in an open container its toxicity diminishes with a coincidental volatilization of basic material. The volatile substance can be identified as ammonia.
Death resulting from the injection of comparatively large amounts of ammonium salts (0.1 gm.) is easily distinguished from that due to botulism, both through the character of the symptoms and the absence of an incubation period. However, when the amount of toxic salts injected is smaller (0.01 gm.), the symptoms of poisoning are not so characteristic and death may be delayed long enough to suggest a period of incubation similar to that observed in botulism (Table IV). This circumstance is of importance in connection with the examination of partly decomposed food products in which the presence of botulinus toxin is suspected. As a rule such suspected material is injected in massive doses (0.5 to 1 cc.) in mice. It is conceivable that such spoiled foods may be contaminated with common putrefactive bacteria yielding ammonia during their growth and thus may cause death of the test animals. If in such tests mice passively protected by the preliminary injection of an excess of antitoxin be used in addition to normal animals, the chances of an error in the interpretation of the results will be materially reduced, though not ruled out. Unfortunately for such a procedure, botulinus antitoxin is not readily available, while furthermore, recent findings indicate that it may not always be effective owing to the existence of a group of toxin-producing bacteria very similar to Bacillus botulinus, but not homologous immunologically with either of the known types of the latter.
The test of thermostability of the toxic constituents of suspected food may conceivably help to determine the true nature of the poison.