DIPHTHERIA 321 



The bacteriological study of diphtheria was commenced 

 by Klebs and Loffler in 1882. Klebs especially investi- 

 gated the pathological histology, and ascribed the disease 

 to small rod-shaped organisms, which he observed in the 

 membrane. It was reserved for Loffler to place this 

 observation of Klebs on a firmer basis by the isolation 

 and cultivation of the bacillus from the membrane, and 

 by the production of certain phases of the disease by 

 inoculation with the isolated organism. The cause of 

 diphtheria is, therefore, this diphtheria bacillus, which, 

 from its discoverers, is frequently known as the Klebs- 

 Loffler bacillus. 



The isolation of the specific organism was accomplished 

 by Loffler by the use of a special culture medium now 

 known as Loffler 's blood-serum, which consists of a 

 mixture of blood-serum (ox serum was that originally 

 used) 3 parts and glucose bouillon 1 part, the whole being 

 coagulated (see p. 76). On this medium the diphtheria 

 bacillus grows and multiplies exceedingly well, while the 

 other organisms associated with it in the membrane are 

 to a large extent inhibited in their growth. 



Diphtheria-like bacilli, so-called " diphtheroid organ- 

 isms," are of wide occurrence, and must not be mistaken 

 for the Klebs-Loffler bacillus (see p. 342). 



Characters of the Diphtheria Bacillus 



Morphology. The B. [Corynebacterium] diphtheria? is a 

 small, delicate bacillus, with rounded ends, frequently 

 slightly curved, and ordinarily measuring 3 ^ or 4 /x in 

 length. It is non-motile and does not form spores. The 

 size varies somewhat even on the same medium, and three 

 varieties of the bacillus have been described, viz., long, 

 medium, and short, according to the length. These 

 varieties tend to be constant and to breed true. Some 



M.B. 21 



