PATHOGENIC BACTERIA. 103 



Bacillus of Diphtheria, (Klebs-Loffler.) 



Origin. In diphtheritic membrane, by Loffler, in 1884. 



Form. Small, slightly curved rods about as long as tubercle 

 bacilli and twice as broad ; the ends are at times swollen ; 

 spores have not been found. 



Properties. They do not possess any movement ; do not 

 liquefy gelatine. They are not very resistant, being destroyed 

 by a temperature of 50 C., but they have lived on blood-serum 

 five months. 



Growth. Grow readily on all media, between temperature 

 of 20 and 40 C. They are facultative anaerobic; they grow 

 quite rapidly and profusely. Egg cultures (Hueppe's method) 

 give good growths. 



Colonies on Gelatine Plates. At 24 C. little round colonies, 

 under low-power, granular centre ; irregular borders. 



Stab Cultures. Small, white drops along the needle track. In 

 glycerine-agar a somewhat profuse growth. 



Potato. On alkaline surface, a grayish layer in 48 hours. 



Blood-Serum (after Loffler). Blood serum 3 parts, and bouil- 

 lon 1 part ; the bouillon contains peptone, 1 per cent., chloride 

 of sodium, per cent., and dextrin, 1 per cent. 



On this medium a very thick yellowish-white layer occurs on 

 the surface, and isolated colonies in the upper strata. 



Staining. Is not colored by Gram's method. Stained best 

 with Loffler's alkaline methylin-blue. 



Pathoyenesis. By inoculation, animals, which naturally are 

 not subject to diphtheria, have had diphtheritic processes de- 

 velop at the site of infection ; hemorrhagic oedema then follows, 

 and death. 



In rabbits paralyses develop, and when the inoculation occurs 

 .upon the trachea, all the prominent symptoms of diphtheria 

 show themselves. 



Manner of Infection in Man. The exact way is not yet known. 

 It is supposed that the mucous membrane altered in some man- 

 ner, the diphtheria bacillus, then gains entrance and the disease 

 develops. 



Products. But it is not the mere presence of the bacillus that 

 gives rise to all trouble ; certain products which they generate 

 get into the system and produce the severe constitutional symp- 

 toms. 



