Definition of the _forms_ | +Ontogenesis.+ | +Phylogenesis.+ of the five first stages | The five first stages | The five first stages of the development of | of the individual | of the phyletic or the animal body. | development. | historical development. -------------------------------+------------------------------+------------------------ | | _First Stage of Development._ | 1. | 1. | +Monerula.+ | +Moneron.+ A simple cytod (a | | plastid without a kernel.) | Animal egg without a | Most ancient animal | | kernel (when the egg-kernel | Monera, originating by | | has disappeared, | spontaneous generation. | | after being fructified). | | | | | | | | | | | | _Second Stage of Development._ | 2. | 2. | +Ovulum.+ | +Amœbæ.+ A simple cell (a | | plastid containing a | Animal egg with kernel | Animal Amœbæ. kernel.) | (a simple egg-cell). | | | | | | | | | | | | | | | | | _Third Stage of Development._ | 3. | 3. | +Morula.+ | +Synamœba.+ A community (an | (_Mulberry form._) | aggregation of identical | | An aggregation of simple cells). | Globular heap of homogeneous | Amœbæ. | | “cleavage spheres.” | | | | | | | | | | | | _Fourth Stage of Development._ | 4. | 4. | +Planula.+ | +Planæa.+ A solid or bladder-shaped, | (_Ciliated larva_.) | globular, or oval | | Many-celled primæval body, _composed of two | Many-celled larva | animal without kinds of different cells_: | without mouth, composed | mouth, composed of externally ciliated, | of different cells.