Resistant stages, which serve for transmission to other hosts, are according to Schaudinn[17] first formed when the diseased portions commence to heal, or more accurately, the recovery commences when the vegetative increase of the amœbæ in the intestine discontinues. The so-called spores of _E. histolytica_ were distinguished very definitely from those of _E. coli_; they were said to consist of spheres of only 3 to 7 µ in diameter, which were surrounded by a double membrane, at first colourless, but becoming a light brownish yellow colour after a few hours, and possessing a protoplasmic content containing chromidia. They were said to arise by fragments of chromatin passing outwards from the nucleus of the amœba into the surrounding cytoplasm (fig. 9, _a_) and undergoing so marked an increase that finally the whole cytoplasm became filled with chromidia. The remainder of the nucleus underwent degeneration and became extruded. On the surface of the cytoplasm there then arose small protuberances containing chromidia. These processes had been observed in the living organisms. They gradually divided and separated from membranes which later became yellow. The remainder of the amœba perished. Craig[18] had also seen phases of this process of development. It must be remarked that, according to recent researches, these processes of exogenous sporulation are degenerative in character (see p. 41). The small spores may be fungi. The “sporulation” processes are only mentioned here as a warning. They are now only of historic interest. By means of an experiment made on a cat, Schaudinn ascertained that ingestion of permanent cysts, which resist desiccation, is the cause of the infection. The animal took food containing dry fæces with amœba cysts; these fæces came from a patient suffering from amœbic enteritis in China. On the evening of the third day the cat evacuated blood-stained mucous fæces which contained large numbers of typical _Entamœba histolytica_. On the fourth day after the infection the animal experimented upon died, and the large intestine showed the changes previously stated. [17] _Arb. a. d. kaiserl. Gesundheitsamte_, xix, pp, 547–576. [18] “Life cycle of _Amœba coli_ in Human Body,” _American Medicine_, 1904, vii, p. 299; viii, p. 185. _E. histolytica_ also is found in the large intestine. This was originally shown to be the case by Kartulis, and the fact has recently been confirmed from many quarters. It is also present in the metastatic abscesses of which it is the cause (_cf._ among other authors, Rogers, _Brit. Med. Journ._, 1902, ii, No. 2,177, p. 844; and 1903, i, No. 2,214, p. 1315).