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518 This occurrence of amœbæ in the stools of healthy individuals, and their absence from the stools in a proportion of cases possessing the clinical characters of the type called "amœbic," have suggested caution in definitely accepting the micro-organism as the true cause of this type of dysenteric disease, and suggest a suspicion that after all it may be merely an epiphenomenon. Evidence, however, is steadily accumulating corroborative of Schaudinn's opinion.

Many attempts have been made to induce dysentery by the injection of animals, or by feeding them with material— stools, liver pus, cultures— containing amœbæ. In a proportion of instances, especially where injections were used, amœbic dysentery has resulted. But as it is impossible to secure the amœba in pure culture, unless it may be in liver pus, these experiments are open to the objection that the successes depended possibly not on the amœbæ present, but on other micro-organisms of a pathogenic nature unavoidably introduced at the same time.

Especially important is one of Schaudinn's experiments. It has a very distinct bearing on the way in which dysentery may be acquired tinder natural conditions, and as indicating the necessity for the immediate disinfection or destruction of dysenteric stools. Schaudinn fed cats on fresh dysenteric stool without inducing disease; but when he carefully dried the stools at natural temperatures, that is to say, when he had induced the Entamœbœ histolyticœ, they contained to encyst and form encapsuled spores, and then administered the material to cats, he produced typical amœbic dysentery. In other words, the amœbae in fresh stool, being in their unprotected vegetative state, were destroyed by the gastric with perhaps quite as good a claim to be considered pathogenic, inasmuch as they can be detected only in specially prepared cultures, elude the eye, even of the sharpest observer, in stools prepared in the ordinary way. Craig, Vedder, and Hoyt have found cysts of A. coli in 70 per cent, of Filipinos and in 50 per cent, of American soldiers in the Philippines— the examinations having being made after the administration of Rochelle salts.