Charles Grant Blairfindie Allen (February 24, 1848 - October 25, 1899) was a science writer and novelist, and a successful upholder of the theory of evolution.His first books were on scientific subjects, and include Physiological Æsthetics (1877) and Flowers and Their Pedigrees (1886). He was first influenced by associationist psychology as it was expounded by Alexander Bain and Herbert Spencer, the latter often considered the most important individual in the transition from associationist psychology to Darwinian functionalism. In Allen's many articles on flowers and perception in insects, Darwinian arguments replaced the old Spencerian terms. On a personal level, a long friendship that started when Allen met Spencer on his return from Jamaica, also grew uneasy over the years. Allen wrote a critical and revealing biographical article on Spencer that was published after Spencer was died.