Since Dochez and Gillespie 1 published their series of type determinations in cases of lobar pneumonia, much work of this character has been done. Almost all of the work, however, has been done in cases occurring in the cities, or, at least, in localities where contact would be a large factor.
In a series of cases covering four years at the Pennsylvania Hospital, Philadelphia, it appeared very noticeable that many of the Type IV cases presented a history of some exposure, which the patients considered to be the cause of their pneumonia. This was largely absent in the cases caused by the typical types. The latter, on the other hand, presented more frequently the history of a contact of some sort which would have given opportunity for inoculation with the infecting organism. The Type IV cases seemed to be largely due to a diminished resistance, while the typical types seemed