The great French zoologist Lamarck (1744-1829) was best known for his theory of evolution, called 'soft inheritance', whereby organisms pass down acquired characteristics to their offspring. Originally a soldier, Lamarck later studied medicine and biology, becoming particularly interested in botany. His distinguished career included admission to the French Academy of Sciences (1779), and appointments as Royal Botanist (1781) and as professor of zoology at the Musee Nationale d'Histoire Naturelle in 1793. Acknowledged as the premier authority on invertebrate zoology, he is credited with coining the term 'invertebrates'. In this two-volume work of 1809, he outlines his theory that under the pressure of different external circumstances, species can develop variations, and that new species and genera can eventually evolve as a result. Darwin paid tribute to Lamarck as the man who 'first did the eminent service of arousing attention to the probability of all change ... being the result of law'.