Complex sentence: Then, Henri was admitted at the lycée Fontanes-Condorcet (upper classes) as a lodger, which very selective recruitment was practically Parisian, especially from the same district, and from the smallest republican commercial and civil servants bourgeoisie population.
Split into simpler sentences: Then, Henri was admitted at the lycée Fontanes-Condorcet (upper classes) as a lodger. He faced a very selective recruitment that was practically Parisian, especially from the same district, and from the smallest republican commercial and civil servants bourgeoisie population.