Staining of Fungi With Saccharated Iron Oxide

A 0.2% aqueous solution of saccharated iron oxide with a pH of 10.8 is shown to be suitable for supravital staining of fungi. Colonies or fresh tissue materials presumed to contain fungi are immersed in the solution for 1-24 hr, fixed in a 10% neutral solution of buffered formalin about 1 hr, washed, and treated with 10% potassium ferrocyanide in 0.5 N, HC1. Cell membranes of hyphae, perithekia, and walls of sporangia appear dark blue; cytoplasm of the hyphae, sporangiospores and spores stain greenish blue or yellowish green.