Bacilli Resembling the Diphtheria Bacillus 475 



throats examined in New York; they seem to have no rela- 

 tionship to diphtheria, and are never virulent. 



Morphology. This micro-organism bears a more or less 

 marked resemblance to Bacillus diphtherias, but differs in 

 certain particulars that usually make it possible to recognize 

 and identify it. It is shorter and stouter than its relative, 

 is straight, usually slightly clubbed. It usually stains in- 

 tensely, and commonly shows but one unstained transverse 

 band. When the bacilli are short and have a single band, 

 they may resemble cocci. When longer they may show two 

 transverse bands. 



There are no flagella and no spores. 



Staining. The organism stains intensely and more uni- 

 formly than Bacillus diphtherias . When colored by Neisser's 

 or Roux's method, no metachromatic end bodies can be 

 defined. 



Cultivation. The organism is usually discovered in 

 smears made for the diagnosis of diphtheria, and sometimes 

 occasions considerable confusion through its cultural simi- 

 larities and morphologic resemblances to Bacillus diphtherias. 

 It grows more luxuriantly upon the ordinary culture-media 

 than B. diphtherias. The colonies are larger, less transpar- 

 ent and whiter, as seen upon agar-agar. In bouillon there is 

 more marked clouding and less marked pellicle formation. 

 Upon Loffler's blood-serum the cultures are too much alike 

 to be easily differentiated. 



G. F. Petri * found no substances in filtrates of cultures of 

 Hofmann's bacillus capable of neutralizing diphtheria anti- 

 toxin; he also found that horses immunized with large 

 quantities of filtrates of the Hofmann bacillus did not pro- 

 duce any antitoxin to diphtheria toxin. Eleven different 

 cultures were studied and the results are very important. 



Cobbettf and Knapp| show that there is a chemicobio- 

 logic difference between the true and pseudodiphtheria 

 bacilli, in that the pseudobacillus does not ferment dextrin 

 or any of the sugars as the true bacillus does. 



Chemistry. The chemical peculiarities of the culture 

 serve to make certain that Bacillus hofmanni is an independ- 

 ent micro-organism. Under no circumstances does it pro- 

 duce or can it be made to produce toxin. Under no circum- 



* "Jour, of Hygiene," vol. v, No. 2, April, 1905, p. 134. 

 f "Centralbl. f. Bakt. u. Parasitenk.," 1898, xxm, 395. 

 t "Jour, of Med. Research," xn (N. S., vol. vn), 1904, p. 475. 



