In the first part I present some historical elements related to the “Philosophie Zoologique” by JeanBaptiste Lamarck, a fundamental work of modern biology. This work deserves a special mention in its 200th anniversary, since it contains some important concepts for “The Origin of Species by Means of Natural Selection, or the Preservation of favored races in the struggle for life” the principal work of Charles Darwin. Subsequently we review the pangenesis and various contradictions in the explanation of the variability required for the action of natural selection that culminate with the birth of genetics. In this paper is important show the particular position of Mendelian experiments in relation with the evolutionary paradigm caused by the origin of species.