From decomposing organic matter substances can be separated which have all the characters of alkaloids.

The alkaloids produced by putrefaction are usually known by the name of ptomaines. It was at one time supposed that they were different in their chemical nature from the alkaloids which occur in plants, and they were supposed to have a much greater reducing power than the latter. It was therefore proposed to distinguish between ptomaines and other alkaloids by the addition of potassium ferricyanide: if the alkaloid changed this into ferrocyanide, so that a precipitate of prussian blue was obtained on the addition of ferric chloride, it was supposed to belong to the class of ptomaines; whereas non-reduction was supposed to show that it belonged to the vegetable alkaloids. It was soon found, however, that this test was not trustworthy, for such important alkaloids as morphine and veratrine produced reduction. Later researches, especially those of Brieger, have shown that some at least of the so-called ptomaines are identical with vegetable alkaloids.

We may indeed now regard alkaloids as products of albuminous decomposition, whether their albuminous precursor be contained in the cells of plants and altered during the process of growth, or whether the albuminous substances undergo decomposition from the presence of microbes, either outside or inside the animal body, or by the simple process of digestion by unorganised ferments such as pepsine.

The alkaloidal products formed by the putrefaction of albuminous substances, vary according to the stage of decay at which they are produced. At first the poisonous action of these products may be slight. As decomposition advances, the poisons become more virulent; but after a longer period they appear to become broken up and lose to a great extent their poisonous power.

Muscarine, which is the poisonous alkaloid of some mushrooms, has been made synthetically by Schmiedeberg and Har-nack from choline; and Brieger has obtained from decomposing albuminous substances several well-defined chemical bodies - dimethylamine, trimethylamine, triethylamine, ethylenediamine, choline, neurine, neuridine, muscarine, gadinine, cadaverine, putrescine, saprine, and mydaleine, as well as some substances to which he has given no name. Muscarine, neurine, and choline all have a similar action, their power diminishing in the order just mentioned, choline being much weaker than the other two. They all produce salivation, diarrhoea, vomiting, dyspnoea, paralysis, and death. Muscarine and neurine in frogs produce complete stoppage of the heart in diastole; in mammals they only weaken its action. Neurine, cadaverine, putrescine, and saprine have no marked physiological action; but one alkaloid which Brieger has isolated from human cadavers in an advanced stage of decomposition appears to affect the intestine, causing enormous peristalsis, continuous diarrhoea, lasting for days, and extreme weakness. Mydaleine, obtained from a similar source, is interesting, inasmuch as it causes a rise of temperature; for frequently we find in cases of acute disease that the rise of temperature coincides with the constipation, and is removed by purgation, so that the question arises how far the rise of temperature in such cases may be due to the absorption of poison from the intestine. Mydaleine causes dilatation of the pupil, enormous secretion of tears, saliva, and sweat, vomiting, diarrhoea, paralysis, convulsions, twitching, dyspnoea, coma, and death.

Sepsine, which was isolated by Bergmann and Schmiedeberg from putrefying yeast, causes vomiting, diarrhoea, and bloody stools; but Nicati and Rietschl have produced choleraic symptoms in animals by cultivations of Koch's comma bacillus from which the organisms themselves had been removed; and somewhat similar results were obtained several years ago by Lewis and Douglas Cunningham with cholera stools in which any organisms present had been destroyed by boiling.

1 Compt. rend., xc. 928.

The extract from putrefied maize has a tetanic and narcotic action, which appears to be due to two different substances. These are not present in the same proportion, so that sometimes the tetanising action, and at other times the narcotic action, is most marked.

Another alkaloid, resembling atropine in its action, has been separated by Sonnenschein and Zuelzer from decomposing animal matter; and this has also been found in the bodies of persons dying from typhus fever.

Another which resembles curare in its action has been separated by Guareschi and Mossol from putrefying brain.

Another substance causing tetanic symptoms has also been obtained from animal matter.