Complex sentence: From 1851 he worked as an apprentice at the "Löwenapotheke" in Halle, and during his time spent in Halle he studied under bryologist Karl Müller.
Split into simpler sentences: From 1851 he worked as an apprentice at the "Löwenapotheke" in Halle. During his time spent in Halle he also studied under bryologist Karl Müller.