290 A MANUAL OF BACTERIOLOGY 



general diphtheria ward (unless a prophylactic dose of 

 antitoxin or of an endotoxic vaccine be given), nor would 

 antitoxin be needed in the majority. 



Most authorities have been unable to convert the pseudo- 

 bacillus into a virulent Klebs-Loffler bacillus, or vice versa, 

 and many are of opinion that it has probably nothing to 

 do with diphtheria (Park and Beebe, Peters, Washbourn, 

 Cobbett, Clark). A few fatal cases have been recorded 

 (e.g. by Stanley Kent) in which a careful search has failed 

 to reveal any but Hofmann bacilli. Boycott 1 found that 

 the seasonal prevalence of the Klebs-Loffler and Hofmann 

 bacilli does not correspond, the former prevailing during 

 September, October, and November ; the latter is more 

 frequent from May to August. 



Priestley records an outbreak of what he terms " pseudo- 

 diphtheria," in which the Hofmann bacillus seemed to 

 be the causative organism, and expresses the opinion 

 that this bacillus is not related to the Klebs-Loffler 

 bacillus. 2 



Salter 3 claimed to have found that the Hofmann bacillus 

 is virulent to many small birds (goldfinch, chaffinch, canary, 

 etc.), and that by successive passages it becomes converted 

 morphologically into a Klebs-Loffler form with feeble 

 virulence for the guinea-pig. He also found the filtered 

 broth culture of the Hofmann bacillus, though harmless to 

 guinea-pigs, to be toxic to small birds, and that it contains 

 a non-toxic substance (toxoid) which has the power of 

 combining with, and neutralising, diphtheria antitoxin. 

 Salter concluded, therefore, that diphtheritic organisms 

 are to be met with of every grade of virulence, the weakest, 

 known as Hofmann's or the pseudo- diphtheria bacillus, 

 representing the most attenuated form of the Klebs-Loffler 



1 Journ. of Hygiene, 1905, vol. v, p. 223. 



2 Public Health, July 1903. 



3 Trans. Jenner Inst. Prev. Med., vol. ii, p. 113. (Bibliog.) 



