Letter, 'Addition to a former paper on Trichophyton tonsurans' from George Thin to Michael Foster Thin expands upon an earlier paper [see PP/1/18], writing: 'In the “Proc. Roy. Soc.,” vol. 33, p. 234, 1881, a paper of mine is published on Trichophyton tonsurans. Since the time that the investigations recorded in that paper were made, the study of parasitic fungi has been greatly facilitated by the introduction by Dr Koch of gelatinised meat juice as a medium for cultivation, and having again studied the development of Trichophyton with the advantages derived from the use of this medium, I believe that two results which I have obtained might be usefully published as a supplement to the paper referred to.' Annotations in pencil and ink. Subject: Dermatology / Pathology Received 7 December 1885. Read Communicated by Foster. A version of this paper was published in volume 39 of the Proceedings of the Royal Society as 'Addition to a former paper on Trichophyton tonsurans'. 2 December 1885