Dr P. W. Latham, in the Harveian oration at the Koyal College of Physicians, on October 17, 1888, supported my own researches (which have already been published in the Proc. Roy. Soc. Edin., vol. xiv. pp. 97–106, and vol. xv. pp. 33–63), on the subject of “disease germs.” He says:—” “We might hope to find that the action and growth of the bacilli [of phthisis] might be inhibited by certain substances, and then, by injecting these substances into the blood, disease might be prevented, or if disease existed it might be arrested or cured.”