32 Comparative Studies 



it can be stated with safety that a culture which fails to 

 give the granule formation under the proper conditions 

 is not a culture of the true diphtheria bacillus ; on the 

 other hand, a culture which gives a positive result is most 

 probably not pseudo-diphtheria. He is not convinced 

 that his former opinion as to the identity of the 

 two groups is erroneous, and that we have to deal 

 with two distinct, if very closely related, forms of bac- 

 teria. 



Muir and Ritchie (39) state that " the term xerosis 

 bacillus has been given to an organism first observed by 

 Kuschbert and Neisser in xerosis of the conjunctiva, and 

 which has since been found in many other affections of the 

 conjunctiva, and even in normal conditions. Morphologi- 

 cally, it is practically similar to the diphtheria bacillus, 

 and even in cultures presents very minor differences. It 

 is, however, non-virulent to animals and, according to 

 Eyre, does not produce an acid reaction in neutral bouil- 

 lon ; in this way it can be distinguished from the diph- 

 theria bacillus." 



Gliicksmann (40) states that the pseudo-diphtheria bacilli 

 are shorter and more plump than the true diphtheria bacilli r 

 mostly pointed at both ends, wedge-shaped ; less frequently 

 they are club-shaped. In the children's hospital he found, 

 in cases which showed no membrane, and had no fever, 

 that the pseudo-diphtheria bacillus was present in twenty 

 out of thirty-nine cases examined. L,arge quantities of a 

 culture of the pseudo-diphtheria bacillus were inoculated 

 into guinea pigs without producing any effects, except at 

 times a slight local infiltration. The pseudo-diphtheria 

 bacillus was found not to immunize the guinea pigs against 

 the diphtheria bacillus. An animal inoculated twenty 

 times with large doses (15 c. c.) of a culture failed to show 

 any immunization, as it died promptly when inoculated 

 with diphtheria. He believes that inoculation into ani- 

 mals is the only mode of differentiation. 



