Conversation so far:
What did Alfred Russel Wallace accomplish?
Above all, Alfred Russel Wallace's role as the co-discoverer of natural selection and his work on zoogeography marked him out as an exceptional figure.
What did you discover about vaccinations after reading the Alfred Russel Wallace article?
In the early 1880s, Alfred Russel Wallace was drawn into the debate over mandatory smallpox vaccination.

Question: What did he do in 1890?
Self-contained rewrite: What did Alfred Russel Wallace do in 1890?