236 A MANUAL OF BACTERIOLOGY 



Two microbes were originally isolated by Klebs 

 and Loffler from human diphtheritic membranes; 

 but Dr. Klein 1 has shown that the Klebs-Loffler 

 bacillus No. 1 is not constant in diphtheritic mem- 

 branes, does not act pathogenically on animals ; and 

 does not grow on solid gelatine at 20 C. In fact, 

 this microbe has been termed the pseudo-diphtheria 

 bacillus. The other species, Klebs-Loffler bacillus 

 No. 2, is always present in diphtheritic membranes 

 in fact, it is present even in the deeper layers of 



\ 



,' 



FIG. 46. BACILLUS DIPHTHERIA (Klein). 



A, The Bacillus x 1000. B, Section through the mucous membrane of 

 pharynx of a child dead of diphtheria. C, Colonies from a plate-cultiva- 

 tion of B. diphtheria. 



the membranes in great masses, and almost in pure 

 culture. This microbe acts virulently on animals, 

 and grows on gelatine at 19-20 C. Klein considers 

 this bacillus to be the true microbe of diphtheria 

 (Fig. 46 A and B). 



On the slanting surface of gelatine in tubes, 



1 'Etiology of Diphtheria' in Reports to Local Government 

 Board, 1889-90, p. 143; Proc. Roy. Soc., 1890; Centralblatt fur 

 Bakteriologie, Bd. vii. (1890). 



