612 PATHOGENIC MICROORGANISMS 



always found together in this form of disease and were regarded by 

 the first observers as representing two distinct forms dwelling in sym- 

 biosis. More recently Tunnicliff, 1 on the basis of experimental work, 

 has claimed identity for the two forms, believing that they represent 

 different developmental stages of the same organism. 



The fusiform bacilli described by Vincent, Plaut, Babes, and others, 

 are from 3 to 10 micra in length, and have a thickness at the center 

 varying from 0.5 to 0.8 micron. From the center they taper gradually 



* 





FIG. 137. THROAT SMEAK. VINCENT'S ANGINA. Fusiform bacilli and spirilla. 



toward the ends, ending in blunt or sharp points. The length of these 

 bacilli may vary greatly within one and the same smear preparation. 

 They are usually straight, sometimes slightly curved. They do not stain 

 very easily with the weaker anilin dyes, but are readily stained by 

 Loeffler's methylene-blue, carbol-fuchsin, or better, by Giemsa's stain. 

 Stained by Gram, they are usually decolorized, though in this respect the 

 writers have found them to vary. Stained preparations show a charac- 

 teristic inequality in the intensity of the stain, the bacilli being more 



1 Tunnicliff, Jour, of Infec. Dis., 3, 1906. 



