A comparative study of the contents of the gelatinous accumulations of the culture media and the contents of the cytoplasm of Amoeba proteus and Arcella vulgaris

Comparative data give the basis for reinterpreting alleged chromidia, mitochondria and Golgi material described for certain rhizopods. Three distinct groups of granules can be demonstrated in both Amoeba and Arcella by techniques ordinarily employed for revealing chromatin elements of a cell, mitochondria or Golgi material. With respect to physico‐chemical properties the granules appear identical with certain forms of bacteria in the culture media. They are not destroyed by alcohol, ether, or Altmann's fluid containing 5% acetic acid. These granules are apparently bacteria; two groups representing permanent cytoplasmic entities either as symbionts or commensals, the third possibly temporary invaders. None of the cytoplasmic inclusions of these rhizopods have given the characteristic mitochondrial reaction when treated with Janus green. Spherules and granules, or alleged Golgi material, in Amoeba blackened with osmic acid can be revealed by techniques ordinarily employed for demonstrating the chromatin elements of a cell. Similar spherules and granules occur in the gelatinous material of the culture media, free or in bodies similar to those sometimes found in food vacuoles. In Arcella, neutral‐red‐stainable and osmiophilic bodies, apparently identical with granules or small globules found individually distributed in the cytoplasm, can be observed both in food bodies in food vacuoles and in similar food organisms in the medium. Those occurring in the cytoplasm may represent indigestible material.