Complex sentence: Alibert believed that when diagnosing skin disorders several criteria needed to be used, and tried to introduce a classification system for diseases that was similar to the method Bernard and Antoine Laurent de Jussieu used in botany.
Split into simpler sentences: Alibert believed that when diagnosing skin disorders several criteria needed to be used. He devised a system of classifying skin diseases, similar to the method Antoine Laurent de Jussieu used in botany.