Of the genus of monera which we call protamœba I have given an illustration in my _History of Creation_ (tenth edition), which has been frequently reproduced. Several species (at least two or three) of this genus still exist, and are distinguished by the shape of their flap-formation and their method of motion. They resemble ordinary simple amœbæ, and only differ from these to any extent in the absence of a nucleus. The _protamœba primitiva_ seems to be pretty widely distributed; it has been found repeatedly by observers (Gruber, Cienkowski, Leidy, etc.) in inland waters. In the zoological demonstrations which I have given at the University of Jena for forty years, and in the course of which the lowly inhabitants of our fresh water are regularly examined with the microscope, the _protamœba primitiva_ has been found four or five times. It always had the same form, as I described it, moved about by the slow formation of flaps at its surface, multiplied by simple cleavage, and showed no trace of a nucleus in its homogeneous plasma-body even with the most careful application of the modern methods of tinting the nucleus. A larger number of very fine granules (microsoma) that were irregularly distributed in the plasm, and were more or less colored by nucleus-reagents, cannot be reckoned as clear equivalents of the nucleus in this or in similar cases; they are probably products of metabolism. The same may be said of the larger marine form of rhizomoneron, which A. Gruber has recently called _pelomyxa pallida_. The large marine form of rhizomoneron to which Huxley gave the name of _bathybius Haeckelii_ in 1868, and as to the real nature of which many opinions have been expressed, seems, according to the latest investigation, not to have the significance ascribed to it. However, the much-discussed question of the bathybius is superfluous as far as our monera theory and the associated hypothesis of archigony (chapter xv.) are concerned, since we have now a better knowledge of the much more important monera-forms of the chromacea and bacteria.