172 BACTERIOLOGY OF THE EYE 



lacrymal sac excision. Rymowitsch found the Dijdobacillits six times in 

 100 normal cases. B. Harman found it on the normal conjunctiva, 

 as did Erdmann, who agreed with Biard that the Diplobacillns can 

 sometimes be met with in the noses of healthy persons, 1 without 

 causing any disease there. When introduced with the conjunctiva, 

 however, it causes an inflammation. Provided that the organisms 

 found on the conjunctiva were pathogenic, a definite disposition can 

 be presumed, though such is rarely of any marked degree ; this is 

 shown by the numerous family epidemics. There is usually a high 

 degree of contagiousness and susceptibility. 



As acute cases can occur, widespread acute epidemics cannot be 

 excluded, though they have not yet been observed. 



The Diplobacilli have no great tendency to infect wounds of the globe. I have 

 seen severe perforating wounds heal cleanly even in the presence of profuse diplo- 

 bacillary conjunctivitis. Our experience with diplobacillary hypopyon-keratitis 

 teaches us, however, that this organism must be reckoned upon in wounds of the 

 cornea. The variety Diplobacille liquefiant of Petit appears to be especially dan- 

 gerous, and as this organism cannot be distinguished in secretion from other Diplo- 

 bacilli, before every operation and in every wound an examination for Diplobacilli 

 should be made, and treatment adopted if necessary. 



Immunity against the infection only occurs to a very slight degree and very 

 rarely. This is shown by the great chronicity of the process, which rarely heals 

 spontaneously ; also by the frequency of recurrences, whether due to the fact that 

 the Diplobacilli had not quite disappeared on treatment or due to reinfection. 



Differential Diagnosis. 



All other bacilli found in the conjunctiva (diphtheria and xerose 

 bacilli, Koch- Weeks and its allies, B. coli, Friedlander's and Zur 

 Nedden's) are radically different either in shape or staining. 



Friedlander's Pneumobacilli are almost the same size, and decolorize in the 

 same way with Gram ; they do not, however, lie so regularly in pairs, and have a 

 much more definite capsule* than the Diplobacilli, in which the capsule is incon- 

 stant or invisible. The same may be said of the closely allied ozaena bacillus. 



Their cultural peculiarities are quite different. The Pneumobacillus and ozaena 

 bacillus flourish on ordinary media, and that, too, at room temperature. They are 

 especially characterized by the ' nail ' culture in gelatine, which does not occur with 

 the Diplobacillus. 



These two organisms have a well-marked pathogenicity for animals, which the 

 Diplobacillus has not. 



It is quite inexplicable how Pes, under these conditions, could consider the Diplo- 

 bacillus as identical with the Pneumobacillus. That author has merely stated the 

 opinion ; he has furnished no proof. 



The paired arrangement is inconstant in Zur Nedden's bacillus, which is also 



1 Harmau's hypothesis that the Diplobucillus (apparently, too, the Koch-Weeks bacillus) 

 occurs in the stomach, and is transferred by contact during vomiting, is quite without proof. 



