22 



MYCOLOGY 



mondy to demonstrate small particles whose size is only many millior 

 times that of a millimeter. The accompanying figure (Fig. 4) adopted 

 from Fuhrmann' represents the relative size of the spheric bacteria 

 and the rod-shaped organisms, while the breadth of the largest known 

 bacterial cell, that of Beggiatoa mirabilis, which approaches that of a 

 human hair in thickness, is represented in the larger area where the 

 width of the cell is twice its length. 



I 3' 3 



o© 



II 



Fig. 4.- 



-Diagram representing the relative sizes of spheric and rod-shaped bacteria 

 {After Fuhrmann.) 



Spheric 

 Bacteria 



Rod-shaped 

 Bacteria 



The cells exhibit a definite cell wall which differs from that of the 

 higher plants in not containing cellulose. The chemical character of 

 the cell membrane indicates its close relationship to the living proto- 

 plasm of the cell. Chitin has been found in the cell wall of some 

 bacteria. Frequently the cell membrane undergoes a mucilaginous 

 modification, so that the filamentous forms are surrounded by a sheath 



• Fuhrmann, F.: Voriesungen iiber Technische Mykologie, Fig. 7, page 17. 



