Finnish lichenologist William Nylander is generally considered to have been the first to demonstrate the use of chemicals to help with lichen identification. In papers published in 1866, he suggested spot tests using KOH and bleaching powder to get characteristic colour reactions—typically yellow, red, or green. In these studies he showed, for example, that the lichens now known as Cetrelia cetrarioides and C. olivetorum could be distinguished as distinct species due to their different colour reactions: C+ red in the latter, contrasted with no reaction in the former. Nylander showed how KOH could be used to distinguish between the lookalikes Xanthoria candelaria and Candelaria concolor because the presence of parietin in the former species results in a strong colour reaction. He also knew that in some cases the lichen chemicals were not evenly distributed throughout the cortex and the medulla due to the differing colour reactions on these areas. In the mid-1930s, Yasuhiko Asahina created the test with para-phenylendiamine, which gives yellow to red reactions with secondary metabolites that have a free aldehyde group. This spot test was later shown to be particularly useful in the taxonomy of the family Cladoniaceae.