The 24 photographs shown here - lantern slides - were created by William McCalla, a Canadian botanist and teacher. The colours of each one were added by hand.
Born in 1872, McCalla published the illustrated book "Wild Flowers of Western Canada" in 1920. Two years later, he became librarian for Edmonton Normal School and later a teacher of the study of nature. From 1925 to retirement in 1938, McCalla taught natural history at a school in Calgary.
Over the course of his career, McCalla crafted over 1,000 such hand-coloured lantern slides of plants and animals. In 1956, the University of Alberta presented him with an honorary degree and in 1960, McCalla gave his herbarium collection - around 14,000 sheets, to the University.
McCalla died in 1962, aged 90.
All pictures: Provincial Archives of Alberta / Retronaut