"Monads" occur two microscopic inhabitants of fresh water, which in the perfectly simple and structureless constitution of their unnucleated, radiate protoplasmic body resemble Protogenes—the genera Protomonas (Monas amyli) and Vampyrella (the latter in three different species); they differ, however, from Protogenes in their mode of propagation. Whereas Protogenes, after it has grown to a certain size, does not gain any further increase of mass, but directly breaks up into two fragments, Protomonas and Vampyrella retract their rays, and pass into the inactive state, and meanwhile the little protoplasmic globule becomes encysted, or surrounded with an envelope (cyst). While so encysted, Protomonas breaks up into a great number of smaller globules, and Vampyrella into four fragments (tetraspores). All of these afterward become free, and by a simple process of growth are developed into the perfect form.
In the mean time I had myself observed, in fresh water at Jena, a fourth allied genus of extremely simple organisms, in all respects like the common Amœba, but distinguished from it by having no cell-nucleus, and no contractile vesicular envelope; hence I named it Protamœba primitiva. While in the first-named three slime-globules (Protogenes, Protomonas, and Vampyrella) numerous filaments radiate from the entire surface of the central protoplasmic body, in Protamœba, on the contrary, just as in the common Amœba, there are only a few short, finger-shaped processes, which are constantly changing, being now retracted, and again pushed out in some other place. When Protamœba has, by taking in food—which operation it performs after the manner of Amœba—attained a certain size, it breaks up by division into two parts. I first published my observations of Protamœba in the "Generelle Morphologie," vol. i., p. 133. Afterward I published figures of Protamœba primitiva, which are to be found in my "Natural History of Creation," sixth German edition, p. 167, and in my "Anthropogenic," third edition, p. 414,
Backed by these observations, which were still further prosecuted afterward by other investigators, and also by myself, I, in 1866, in the "Generelle Morphologie," established a special class, that of Moneres (i. e., simple), for all these organisms of most simple constitution, la the first volume of that work I wrote as follows:
