Authorities in toxicology appear to agree in including convulsions among the effects of belladonna and of its active principle—atropia—on man. Convulsive and tetanic symptoms would appear to be also nearly constantly produced when fatal doses of this poison are administered to dogs, rabbits, and other animals, and to various birds. The recent remarkable progress of our knowledge of the exact and intimate physiological action of various medicinal substances is greatly due to investigations that have been made on animals of a lower type of organisation; and, accordingly, numerous observers have instituted experiments with atropia on such animals, and, especially, on frogs.