The hypothesis of the symbiont, by Altmann and Schimper, 1890, stated that mitochondria and chloroplasts may be considered as intracellular parasites which have entered in the cytoplasm of eukaryotic cells in the early evolutionary period and remains in the symbiotic relationship with eukaryotic cells. Mitochondria are supposed to be derived from bacterial cells while chloroplasts have been derived from blue green algae.