Sentence:  I felt that it was almost as useless for Europeans to go out amongst the tribes of monkeys and spend their lives trying to bring them up to such a level of intelligence as is implied in the appreciation of the Christian religion, as for the Limanorans to <WSD>apostolise</WSD> amongst mankind, and struggle to drag them up to the stage of progress these islanders had reached. 
Meaning of the word marked with <WSD> tags:  To proselytize.