BACTERIOLOGY 



In tubercle bacilli this beaded appearance is common, and 

 the unstained spaces are considered by A. Coppen Jones to be 



of the nature of vacuoles. 

 It is doubtful whether this 

 is correct ; on the contrary, 

 it is more probable that 

 the beaded structure rep- 

 resents a fragmentation of 

 /E rnJ^ ^ e P roto pl asm > which is 



\ S "VH a P nase m a ^ cellular de- 



/? s&^ r ^ r ~~^kr r ^" generation. 



%pr & According to Butschli, 



in Bact. lineola, the central 

 body is surrounded by an 

 envelope of protoplasm 

 corresponding to the cyto- 

 plasm of other cells. If 

 such a cytoplasmic layer 

 exists in other species of bacteria, it is too thin to be differen- 

 tiated from the outer capsule. Whether the central body is a 

 true nucleus or not cannot be positively decided, but there is no 

 good reason to believe that it is. 



That the central body is a distinct structure from the outer 

 capsule is demonstrated by the phenomenon of plasmolysis. 

 Thus when bacteria are placed in a 2.5 per cent potassium 

 nitrate or a 1 per cent sodium chloride solution, the central 

 body contracts, and separates itself in places from the capsule, 

 as shown in Fig. 1, D. 



The bacterial plasma in certain species may show the pres- 

 ence of granular bodies, as in B. butyric us, Vibrio bugula, and 

 Bact. Pastcnrianum, which stain bluish or violet-black with 

 iodine ; the so-called granulosc reaction. The exact nature of 

 granulose is not known. It may be identical with starch, or, at 

 any rate, is a closely related carbohydrate. 



Fig. 1. Showing structure of bacterial cell. 



A. Bact. lineola after Butschli, a capsule, b proto- 

 plasmic layer, c nuclear body. B. Bact.oxyla- 

 tuum afi'-r Migula, a capsule, b central body, 

 c vacuole, d metachromatic granules. C-D. 

 plasmolysis of bacterial cell. E. bacilli, show- 

 ing metachromatic granules. 



