1. 1809 Philosophique Zoologique, Chap. VII.; translation, American Naturalist, 1888, p. 960.
2. 1871 Proceedings of the American Philosophical Society, p. 259; On the Method of Creation of Organic Types, reprinted in Origin of the Fittest, 1887, p. 210.
3. 1872 Penn Monthly Magazine, on Evolution and its Consequences; reprint, Origin of the Fittest, 1887, p. 30.
4. 1877 American Naturalist, p. 607, on the Laws of Digital Reduction.