[ 16 ] Albert Hofmann (shown here in 1993) purified psilocybin and psilocin from Psilocybe mexicana in the late 1950s. Two diethyl analogs (containing two ethyl groups in place of the two methyl groups) of psilocybin and psilocin were synthesized by Hofmann: 4-phosphoryloxy-N,N-diethyltryptamine , called CEY-19, and 4-hydroxy-N,N-diethyltryptamine , called CZ-74.