PLANULA • E-FREE TRANSLATION.COM • Definition of Planula

... of amoebae (synamoebae), corresponding to the mulberry-yolk in the first development of the fecundated egg, and to some still living heaps of amoebae. To the fourth stage he assigns the planaea, corresponding to the embryonic development of an albumen and the planula or ciliated {48} larva. When these ciliated larvae are developed, they contract themselves so as to form a cavity; and this fifth stage—especially important for his theory—he calls gastraea. In this form, he says, the progaster is already ...

— The Theories of Darwin and Their Relation to Philosophy, Religion, and Morality • Rudolf Schmid