Although diphtheria and diphtheroid diseases are of very frequent occurrence, the mouth and tongue are but rarely affected, in spite of their exposed position and liability to injury. The micro-organisms which are responsible for the deadly group of pseudo-membranous inflammations must traverse the mouth in order to gain access to those structures in which they most commonly develop their nefarious activity, yet the oral mucous membrane, where the conditions in general are very similar to those at the points of selection, is practically immune to the influence of the micro-organisms in question.
It is the great rarity of oral diphtheria that has led a number of authors to deny its existence as a primary disease, while admitting its possible, but very infrequent occurrence as a secondary manifestation.
While the case I report is, etiologically, not one of true diphtheria, since it was not caused by the Klebs-Loeffler bacillus, the invariable