“ The second law is often referred to as Lamarck’s hypothesis of the evolution of organs in animals by appetence or longing, although he does not teach that the animal’s desires affect its conformation directly, but that altered wants lead to altered habits, which result in the formation of new organs as well as in modification, growth or dwindling of those previously existing. ”

“ Life by its proper forces tends continually to increase the volume of every body possessing it, and to enlarge its parts, up to a limit which it brings about.
2. “The production of a new organ in an animal body results from the supervention of a new want (besoin) continuing to make itself felt, and a new movement which this want gives birth to and encourages.
3. “The development of organs and their force of action are constantly in ratio to the employment of these organs. ”

“ In 1793, in consequence of changes in the organization of the natural history department at the Jardin du Roi, where he had held a botanical appointment since 1788, Lamarck was presented to a zoological chair, and called on to lecture on the Insecta and Vermes of Linnaeus, the animals for which he introduced the term Invertebrata. Thus driven, comparatively late in life, to devote his principal attention to zoology instead of botany, he had the misfortune soon after to suffer from impaired vision ”