Complex sentence: In 1839 he returned to France, where he was involved with silkworm cultivation, and from 1843 until his death in 1870, he worked as a botanist in Pondicherry.
Split into simpler sentences: In 1839 he returned to France, where he became involved with silkworm cultivation. From 1843 until his death in 1870, he worked as a botanist in Pondicherry.