Paper, 'On the influence of certain natural agents on the viru­lence of the tubercle-bacillus' by Sheridan Delépine and Arthur Ransome The authors write: 'Three years ago Dr. Ransome communicated to the Society the results of some experiments, carried out in concert with Professor Dreschfeld, of Owens College, “On certain conditions that modify the virulence of the bacillus of tubercle" [see PP/17/3]. The tendency of these researches was to prove “that fresh air and light, and a dry and sandy sub-soil, have a distinct influence in arresting the virulence of the tubercle-bacillus; that darkness some­what interferes with this disinfectant action; but that mere exposure to light, in otherwise bad sanitary conditions, does not destroy the virus.”' They present the results of similar experiments. Annotations in pencil and ink. Subject: Pathology / Bacteriology Received 1 May 1894. Read 24 May 1894. A version of this paper was published in volume 56 of the Proceedings of the Royal Society as 'On the influence of certain natural agents on the viru­lence of the tubercle-bacillus'. 1894