476 Diphtheria 



stances can it be made to produce acid through the decompo- 

 sition of sugars. 



Pathogenesis. Bacillus hofmanni is not pathogenic for 

 any of the laboratory animals. Animals immunized to 

 repeated injections of its cultures acquire no resistance to 

 Bacillus diphtheriae. 



Dr. Alice Hamilton* carefully studied 29 organisms, of 

 which 26 corresponded fully with the pseudodiphtheria 

 bacilli. They were divisible into three groups: I, Those 

 non-pathogenic for guinea-pigs; II, those that produce 

 general bacteremia in guinea-pigs, and are neutralized by 

 treatment with the serum of a rabbit immunized against a 

 member of the group; III, organisms which form gas in 

 glucose media, produce bacteremia in guinea-pigs, and are 

 neutralized neither by diphtheria nor by pseudodiphtheria 

 antitoxin. Some of the organisms of the second group are 

 also pathogenic for man. Instead of regarding the pseudo- 

 diphtheria bacillus as a harmless saprophyte, Dr. Hamilton 

 believes it an important organism explaining some of the 

 paradoxes that we find at hand. Thus, cases of supposed 

 diphtheria irremediable by or deleteriously affected by anti- 

 toxic serum may depend upon one of these organisms. It 

 is also probably one of them that Councilman found in his 

 case of "general infection by, Bacillus diphtheriae," and that 

 Howard encountered in his case of acute ulcerative endo- 

 carditis without diphtheria, from the valves of whose heart 

 cultures of a diphtheria-like organism not pathogenic for 

 guinea-pigs were isolated. 



The still more recent and comprehensive work of Clark | 

 shows that no kind of manipulation is capable of so modifying 

 Bacillus hofmanni as to make its identity with B. diphtheriae 

 in the least likely. Clark is, however, willing to admit the 

 probability that the organisms may have descended from a 

 common stock. 



BACILLUS XEROSIS. 



This bacillus was first described in 1884 by Kutschbert and 

 Neisser,t who regarded it as the cause of xerosis conjunctivae, 

 having found it upon the conjunctiva in that disease. It has, 

 however, been so frequently found upon the normal conjunc- 



* "Jour. Infectious Diseases," 1904, i, p. 690. 



t "Journal of Infectious Diseases," vn, 1910, 335. 



t "Deutsche med. Wochenschrift," 1884, Nos. 21, 24. 



