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 an Italian chemist named Dr. Selmi proved that putrefactive animal matter and certain bacteria yielded alkaloidal products, often poisonous, to which the name of ptomaines was given. Selmi was engaged as an expert in the investigation of a case in which it was suspected that an individual had been poisoned. A product was obtained, apparently an alkaloid, but which Selmi could not identify with any known vegetable substance. He came to the conclusion that it was of animal origin, and after a long series of experiments he proved his theory. Several eminent toxicologists at first asserted that ptomaines could be distinguished from vegetable alkaloids by the property of yielding Prussian blue with ferric salts. This test, however, proved fallacious as several series of vegetable alkaloids, notably the pyridic and the allylic, gave the same reaction. The distinction between animal and vegetable alkaloids is a delicate one, and has to be established by an accumulation of chemical evidence.

Leucomaines, which are also alkaloidal products, are distinguished from ptomaines by being formed in the body from living tissues, as a result of their activity. These were first separated by Armand Gautier in 1886. Their constitution is more complex than is that of the ptomaines, but they are not generally of a poisonous character.