[435] Term first introduced in Die Kalkschwämme, p. 468, 1872.
[436]"On the Primitive Cell-layers of the Embryo as the Basis of Genealogical Classification of Animals, and on the Origin of Vascular and Lymph Systems," Ann. Mag. Nat. Hist. (4), xi., pp. 321-38, 1873.
[437] First distinguished in Die Kalkschwämme, i., p. 465.
[438] Even in the 'seventies it was still believed by many that the egg-nucleus disappeared on fertilisation. The true nature of the process was not fully made out till 1875, when O. Hertwig observed the fusion of egg- and sperm-nuclei in Toxopneustes (Morph. Jahrb., i., 1876).
[439] Studien z. Gastræa-Theorie, p. 214, 1877. These forms were known even in 1870 (Carter, Ann. Mag. Nat. Hist. (4), vi., pp. 346-7), to be Foraminifera. The figures of supposed collar-cells, etc., do credit to Haeckel's imagination.
[440] History of Creation, Eng. Trans., ii., pp. 278 ff.
Systematische Phylogenie, iii., p. 41, Berlin, 1895.
[442] "Notes on the Embryology and Classification of the Animal Kingdom," Q.J.M.S. (n.s.), xvii., pp. 399-454, 1877.
[443] It was "part of the non-historic mechanism of growth" (loc. cit., p. 418).