312 TEXT-BOOK OF BACTERIOLOGY. 



that there must be an essentially local process, whose action upon 

 the entire organism was promoted by the absorption of dissolved 

 and injurious substances produced by bacteria, and that the real 

 bearers of the poison would only be found in the local changes. 

 But these very changes by no means afford a proper field for 

 bacteriological purposes. While the mouth and the mucous mem- 

 branes of the adjacent regions teem with divers bacteria under 

 ordinary circumstances, their number increases considerably when- 

 ever these parts become diseased. The ulcerous processes formed 

 during diphtheria from the destruction and expulsion of the super- 

 ficial layers, afford to these micro-organisms an excellent medium 

 for undisturbed settlement and limitless reproduction. They grad- 

 ually advance into the tissue, immigrate into the inflammatory and 

 coagulated accumulations characterizing diphtheria, and, finally 

 cause a motley array of most diversified forms. Errors and mis- 

 interpretations were a natural consequence. Only by extreme* 

 caution and keen judgment of his own results, did Loftier succeed 

 in finding the way out of this confusion. 



In the course of extensive investigation he discovered in the 

 changed mucous membranes of diphtheria patients a kind of bac- 

 terium distinguishable from other bacteria hitherto known ; he was 

 able to cultivate them artificially and to employ them for success- 

 ful transmissions. These results determined him (of course, only 

 conditionally and with every reserve) to ascribe to this micro- 

 organism particularly close, perhaps causative relations to the de- 

 velopment of diphtheria. 



Loffler's statements have been confirmed and amplified by 

 further investigations. A great number of observers, among 

 them Babes, Kolisko and Paltauf, Zarniko, Escherich and d'Espine, 

 have established the regular occurrence of Lender's bacilli in all 

 cases of diphtheria and proved that they alone belong exclusively 

 to this affection. Finally, Roux and Yersin, by means of the bacilli, 

 have been able to produce in animals quite the same symptoms 

 that are peculiar to human diphtheria and they obtained paralysis 

 of a typical kind, so that we regard Loffler's bacilli beyond doubt 

 as the exciter of human diphtheria. 



The bacteria occur within the diphtheritic pseudo-membranes 

 and in the oldest parts of these. They are surrounded by a copious 

 accumulation of cells and do not, as a rule, advance as far as the 

 chief mass of the membranous accumulation which is characterized 

 rather as a layer of exudation containing few if any cells and 

 bacteria. 



They are little rods of moderate size, usually slightly bent, 



