D. The two daughter-cells, produced by the complete division of the two nuclear halves (cytosomata still connected at the equator) (Double-knot, Dispirema) 1. Upper daughter-nucleus 2. Equatorial constriction of the cell-body 3. Lower daughter-nucleus. Fig. 11—Indirect or mitotic cell-division (with caryolysis and caryokinesis) from the skin of the larva of a salamander. (From _Rabl._). When we examine a little closer the original features of the ovum, we notice the extremely significant fact that in its first stage the ovum is just the same simple and indefinite structure in the case of man and all the animals (Fig. 13). We are unable to detect any material difference between them, either in outer shape or internal constitution. Later, though the ova remain unicellular, they differ in size and shape, enclose various kinds of yelk-particles, have different envelopes, and so on. But when we examine them at their birth, in the ovary of the female animal, we find them to be always of the same form in the first stages of their life. In the beginning each ovum is a very simple, roundish, naked, mobile cell, without a membrane; it consists merely of a particle of cytoplasm enclosing a nucleus (Fig. 13). Special names have been given to these parts of the ovum; the cell-body is called the _yelk_ (_vitellus_), and the cell-nucleus the _germinal vesicle._ As a rule, the nucleus of the ovum is soft, and looks like a small pimple or vesicle. Inside it, as in many other cells, there is a nuclear skeleton or frame and a third, hard nuclear body (the _ nucleolus_). In the ovum this is called the _germinal spot._ Finally, we find in many ova (but not in all) a still further point within the germinal spot, a “nucleolin,” which goes by the name of the germinal point. The latter parts (germinal spot and germinal point) have, apparently, a minor importance, in comparison with the other two (the yelk and germinal vesicle). In the yelk we must distinguish the active _formative yelk_ (or protoplasm = first plasm) from the passive _ nutritive yelk_ (or deutoplasm = second plasm). Fig.12 Mobile cells from the inflamed eye of a frog. Fig. 12—Mobile cells from the inflamed eye of a frog (from the watery fluid of the eye, the _humor aqueus_). The naked cells creep freely about, by (like the amœba or rhizopods) protruding fine processes from the uncovered protoplasmic body. These bodies vary continually in number, shape, and size. The nucleus of these amœboid lymph-cells (“travelling cells,” or planocytes) is invisible, because concealed by the numbers of fine granules which are scattered in the protoplasm. (From _Frey._)