Chapter Iii. _the Atom._ in the Text I Have Quoted the Great Masters,

Ehrenberg, Dujardin, Pouchet, Heterogenie. In the end spontaneous generation will conquer.

Chapters IV., V., VI., &c. Throughout this book, in ascending from inferior to superior life, I have taken for my guiding thread in the great labyrinth, the hypothesis of Metamorphosis but without serious intention of constructing a chain of beings. The idea of ascending Metamorphosis is natural to the mind, and is, in some sort, irresistibly imposed upon us. Cuvier himself, at the close of his Introduction to his Poissons, confesses that if that theory has no Historical value it has a logical value. On the Sponge, see Paul Gervais Dict. d'Orb. V. 375; Grant in Chenn, 307, &c. On Polypes, Corals, and Madrepores (Chapters 4 and 5) besides Forster, Peron and Dawin consult Quoy and Gaimard; Lamouroux, Polypes Flexibles; Milne Edwards, Polypes and Ascidies of the Channel, &c. On the Calcaire, see the two Geologies of Lyell.