Upon the Pseudo- Diphtheria, etc. 29 



stained for from three to five seconds in vesuvin, washed in 

 water and examined. This process will show beautiful 

 double staining of the diphtheria bacilli, when grown on 

 LofHer's blood serum for ten to twenty hours at 34 to 

 35 C., while the pseudo-diphtheria bacilli show no double 

 staining. Neisser believes it would be best to drop the 

 name pseudo-diphtheria, and "designate as pseudo-diph- 

 theria bacilli only those described by von Hofmann and 

 Loftier. The only difficulty in differentiation is with the 

 group of xerosis bacilli and a group of rather thick, short 

 strepto-bacilli." He reports on a careful study of twenty-two 

 bacilli resembling the lyofHer bacillus. Some of these were 

 derived from the throat, from the nose in nasal diphtheria 

 and from the conjunctiva. When grown on blood serum 

 the growth of the strepto-bacilli was observed. But the 

 similarity between the two is less marked, and there is an 

 absence of the longer forms of the bacilli. When stained 

 by Gram's method they appear larger, and may lead to 

 uncertainty. The xerosis bacilli show very slight growth 

 after six hours. When stained the bacilli appear older 

 than the diphtheria bacilli of the same age. The growth 

 of the xerosis bacilli after ten hours is still not very 

 marked. The picture which they present is sometimes 

 quite similar to that presented by the diphtheria bacilli, 

 the form altogether so ; yet not like the diphtheria bacilli 

 of this age usually appear in such cultures. When studied 

 with the method of double staining which he describes it 

 is only in sixteen- to twenty-hour-old cultures that it 

 becomes possible to make a differential diagnosis; the 

 pseudo-diphtheria bacilli showing a negative appearance, 

 like most of the xerosis forms. At times, however, there 

 are single individuals that take on the characteristic stain- 

 ing, but it is impossible to mistake the picture presented 

 by them for that of the diphtheria bacilli. Cultures several 

 days old (this is especially true of many of the xerosis 

 forms) take on the double staining. 



