28 



MORPHOLOGY 



bacterial cells varies as greatly as does the shape. Within 

 the same species a variation in certain cells of o.i and in others 

 to 3 or 5 microns in length has been noted. Temperature, 

 reaction, and composition of the media, and, in addition to 

 these, the age of the cell are responsible for these variations. 



o 



10 



FIG. 21. The comparative size of bacteria, (i) Bact. influenzas. (2) Bact. 

 tuberculosis. (3) B. typhosus. (4) Bact. anthracis. (5) M. gonorrhoeas. (6) 

 M. pyogenes var. aureus. (7) M. freudemeichii. (8) Msp. comma. (9) Sp. 

 undula. (10) Sp. obermeieri. 



The size of the cells differs when introduced into animals and 

 plants and on the various culture media used for the study 

 of bacteria. It does not seem that breadth is any more con- 

 stant than length among species of bacteria which vary in size. 

 It is interesting to note that one of the smallest observed 

 bacteria, Pseudomonas indigofera (Voges) Mig., is only 0.18 



