Specificity 433 



the surface of the mucous membrane is chiefly affected. 

 The superficial layers of cells being embedded in coagulated 

 exudate fibrin and show a peculiar hyaline degeneration. 

 Sometimes the membrane seems to consist exclusively of 

 hyaline cells ; sometimes the fibrin formation is secondary to 

 or subsequent to the hyaline degeneration. Leukocytes 

 caught in the fibrin also become hyaline. From the super- 

 ficial layer the process may descend to the deepest layers, 

 all of the cells being included in the coagulated fibrin and 

 showing more or less hyaline degeneration. The walls of the 

 neighboring capillaries also become hyaline, and the necrotic 

 mass forms the diphtheritic membrane. The laminated 

 appearance of the membrane probably depends upon the 

 varying depths affected at different periods, or upon differ- 

 ences in the process by which it has been formed. The 

 pseudo-membrane is continuous with the subjacent tissues 

 by a fibrinous reticulum, and is in consequence removed 

 with difficulty, leaving an abraded surface. When the mem- 

 brane is divulsed during the course of the disease, it imme- 

 diately forms anew by the coagulation of the inflammatory 

 exudate. 



The coagulation-necrosis seems to depend upon the local 

 effect of the toxin. Morax and Elmassian *' found that 

 when strong diphtheria toxin is applied to the conjunctiva 

 of rabbits every three minutes for eight or ten hours, 

 typical diphtheritic changes are produced. 



Flexnerf has made a study of the minute lesions caused 

 by bacterial toxins and especially of the diphtheria toxin, 

 and Councilman, Mallory, and Pearce,{ of both gross and 

 minute lesions that the thorough student should read. 



Specificity. Herman Biggs, in an interesting discus- 

 sion of the occurrence of the diphtheria bacillus and its 

 relation to diphtheria, comes to the following conclusions: 



i. "When the diphtheria bacillus is found in healthy 

 throats, investigation almost always shows that the indi- 

 viduals have been in contact with cases of diphtheria. 

 The presence of the bacillus in the throat, without any 



* "Ann. de 1'Inst. Pasteur," 1898, p. 210. 

 f" Johns Hopkins Hospital Reports," vi, 259. 



t " Diphtheria : A Study of the Bacteriology and Pathology of 

 Two Hundred and Twenty Fatal Cases," 1901. 



"Amer. Jour. Med. Sci.," Oct., 1896, vol. xxn, No. 4, p. 411. 

 28 



