464 



COR YNEBACTERIUM 

 TABLE ^0— continued 



Growth in 

 broth. 



Fermentation 

 of starch and 

 glycogen. 



Antigenic 

 structure. 



Gravis. 



Animal 

 pathogenicity. 



Appearance variable. 

 Usually surface pel- 

 licle and coarse granu- 

 lar deposit with little 

 or no turbidity. 



+ 



At least 5 types recog- 

 nizable by direct ag- 

 glutination. Types I 

 and II form the clas- 

 sical daisy-head col- 

 onies ; Types III, IV 

 and V approach nearer 

 to the mitis type. 



Almost invariably viru- 

 lent to guinea-pigs. 



Intermedins. 



Appearance very con- 

 stant. In 24 hours 

 there is slight turbidity 

 with little or no de- 

 posit. In 48 hours 

 broth has cleared, and 

 there is a very finely 

 granular sediment, 

 which can be easily 

 dispersed on shaking. 



Little known, but prob- 

 ably at least 2 types 

 with specific antigens. 



Almost invariably viru- 

 lent to guinea-pigs. 



IVGtis. 



Appearance variable. 

 Usually diffuse even 

 turbidity, denser than 

 that of intermedins, 

 and moderate non- 

 granular deposit. Soft 

 pellicle may form on 

 further incubation. 



Little known, but at 

 least 5 distinct types. 



Usually virulent to 

 guinea-pigs, but strains 

 from carriers are often 

 avirulent. 



Note, q = diameter. 



Fermentation reactions are often of help, since many diphtheroids either ferment 

 sucrose or have no action at all on sugars. Some strains cannot be distinguished 

 except by virulence tests, and even this method leaves the true nature of an avirulent 

 mitis-V\ke organism doubtful. Whether in identifying the individual types of 



# 





•t% 



Fig. 83. — C diphtherice. 



Three colonies of gravis type and two of 

 mitis type, on blood-teliurite-agar ( X 8). 



Fig. 84. — C. diphtherice. 



Colonies of intermedins type on blood- 

 tellurite-agar ( X 8). 



diphtheria bacilli, or in distinguishing between diphtheria bacilli and diphtheroid 

 bacilli that closely resemble them, too much attention should never be paid to 

 any one character. Often it is only by observing all the characters of a particular 



