Lamarck's ideas on evolution were one of the first theories to center around the evolutionary change of species. His first law of evolution dealt with the mechanism by which nature changed living creatures. In his book "Philosophie Zoologique," he proposed that the use or disuse of certain organs and traits was directly related to the changing environment over large spans of time.
Lamarck's theory on evolution posited that organisms change according to the challenges presented by their environment. His second law states that these changes are inherited through generations from a genetic need to improve the species. The Creation Science Tidbits website explains Lamarck's second law as an inherited "desire" to produce offspring that are closer to perfection than the parent generation.
Although popular opinion places Lamarckian evolution at odds with Darwinism, the two agreed on many things. For example, early Lamarck writings hint at the possibility of natural selection on which Darwin later based his evolutionary theories in "The Origin of Species." Although Darwin refuted Lamarck's ideas on inheritable traits, the two evolutionists cited much of the same evidence for their claims.