£-1 Manual of Veterinary Microbiology. 



of the nutrition of n'licrobes ; tliev are secreted for 

 the requirements of digestion, as we have already 

 seen. 



Later, we shall have occasion to see, when consid- 

 ering the role of microbes, that their nutrition is the 

 determining cause of the chemical reactions which 

 characterize fermentations and putrefaction. 



rV". 3Iovements of microbes. 



Some bacteria are immobile (the majority of round 

 and some elongated bacteria), others are gifted with 

 the faculty of moving themselves in the jiuids in 

 which they live. 



The kind of movement varies with the species con- 

 cerned ; sometimes the element, maintaining its recti- 

 lineal direction, performs a simple, more or less regular 

 oscillation around an imaginary longitudinal axis ; at 

 other times it undero-oes a slis^ht inflection in the di- 

 rection of its length and straightens itself again alter- 

 nately ; at other times, again, it assumes a flexuous ap- 

 pearance simulating the movements of a snake ; some 

 even wind themselves around in corkscrew fashion. 



The motion of a certain number of bacteria is de- 

 pendent upon the presence of vibratile prolongations, in 

 others these movements seem to depend upon contrac- 

 tions taking place within the body of the element. 



In all they are directly dependent upon nutrition 

 the integrity of which is necessary to their produc- 

 tion. 



Light and the fluidity of the media are conditions 

 which favor them. 



