328 A MANUAL OF BACTERIOLOGY 



and stomach, and wounds, may be attacked. A pseudo- 

 membrane usually forms, consisting of laminae of fibrin 

 entangling a few leucocytes and other cells, and here and 

 there small effusions of blood, together with coagulative 

 necrosis of the underlying mucous membrane, and the 

 bacilli are for the most part located in the superficial 

 layers of this pseudo -membrane (Plate VI, 6), though in 

 all cases in which the disease has lasted for any time they 

 are found in the lungs, spleen, and kidneys, and may 

 occur even in the blood. If the patient recovers from the 

 diphtheritic attack, paralytic sequelae are not uncommon 

 and are due to a peripheral neuritis. Pseudo -membranes 

 may be formed by other organisms, e.g. by the strepto- 

 coccus and pneumococcus, also by the pneumobacillus, 

 and occur in Vincent's angina (p. 353), but it is doubtful 

 whether paralytic sequelae follow any but a diphtheritic 

 infection. They are certainly excessively rare in non- 

 diphtheritic infections. 



Some remarkable skin affections of an eczematous or 

 ecthymatous nature have been found by Hare l and 

 others to be due to the diphtheria bacillus. 



Another infection which seems to be generally diph- 

 theritic is membraneous rhinitis. Whereas true nasal 

 diphtheria is a serious condition, membranous rhinitis is 

 seldom, if ever, attended with any risk to life, sequelae 

 do not occur, and it is rare to obtain a history of infection 

 from cases of it. This is remarkable and difficult to 

 explain, for virulent diphtheria bacilli are abundant in 

 the nose and nasal secretion. 



Diphtheria bacilli can occasionally be isolated from 

 well people and those not known to have been in contact 

 with diphtheria cases. The incidence varies in different 

 populations ; in Detroit City, U.S.A., about 1 per cent, of 

 the well people was found to be infected among 4,093 



1 Lancet, 1908, vol. i, p. 282. 



