DIPHTHERIA AND GLANDEES GROUP 385 



thei-ia in man. The term diphtheria was originally used 

 by physicians to indicate a characteristic inflammation of 

 the mucous membrane together with formation of a false 

 membrane in the throat or nose. This particular type of 

 infection was said to be diphtheritic. Inasmuch as the 

 organism under discussion is the most common cause of con- 

 ditions of this type in the throat, the term diphtheria is 

 now generally recognized as applying only to lesions pro- 

 duced by this particular organism. 



Morphology. — Young cultures of Corynebacterium diph- 

 thei-icB show rods predominantly 0.4-1.4;u in diameter and 

 1.5-3. 5jLi or more in length. They show marked variation 

 in size and staining characteristics, depending upon the 

 type of medium upon which they are growing and upon the 

 age of the culture. Not infrequently they may stain uni- 

 formly, but more commonly there are deeply-stained bands 

 or granules within the cells. Frequently the cells are 

 slightly curved or pointed and club-shaped. Occasionally 

 branched cells have been noted. 



Cultural Characters. — The organism may be readily 

 secured in culture by rubbing a swab first over the inflamed 

 throat surfaces or upon the false membrane of the diph- 

 theria patient and th^n over the surface of coagulated 

 blood serum. When grown at blood heat upon this medium, 

 development is very rapid; usually colonies may be ob- 

 served in 12 to 18 hours as small pin-pointlike translucent 

 dots, which later become opaque and grayish. It grows 

 best on media containing blood serum or glycerin. It 

 gradually accustoms itself to growth upon artificial media 

 and develops more luxuriantly after many transfers. When 

 grown in broth a delicate scum forms. It will be noted that 

 this pellicle formation is essential in the manufacture of 

 diphtheria toxin already discussed. 



Physiological Characters. — The organism is aerobic and 

 facultative anaerobic. The fact that it does not produce 



