The great majority of investigators believe that trachoma is an infectious disease caused by a specific micro-organism the identity of which has not yet been definitely established. Successful inoculation experiments on human beings and animals seem to prove the communicability of the disease beyond doubt. A great variety of organisms have been described as the cause of trachoma, but all have failed to produce the disease either in man or in experimental animals and have subsequently been shown to be only secondary invaders. The discovery, in 1907, by Halberstadter and von Prowazek1 of characteristic intracellular inclusions in conjunctival scrapings from trachoma was a decided step forward, but the problem soon became complicated by the finding of similar inclusions in various types of nontrachomatous conjunctivitis. At present the inclusion theory does not receive wide acceptance.
A widespread revival of interest in the subject followed the publication in