30 Manual of Veterinary 31kroUology. 



tlie bacterium termo and bacillus subtilis live we do 

 not find the bacillus septicus. 



Under other circumstances it may happen that the 

 two associated germs assist each other, the one pre- 

 paring alimentary materials for the other, or, it may 

 ije, protecting the other from the noxious action of 

 certain agents (association of aerobic and anaerobic 



germs). 



We ous"bt to mention in this connection the influ- 

 ence exerted upon microbes by the tissue elements of 

 animals in which they sometimes live (phagocytosis); 

 we will enter more into the details of this subject in 

 the second part. 



VII. Action of microbes upon the media. 



1. ROLE OF THE BACTERIA IN NATURE. 



From a general biological point of view the role of 

 microbes consists in reducing to the condition of sim- 

 ple inorganic compounds the organic matter built up 

 by vegetables and incorporated by animals. The dis- 

 assimilation which occurs in these beings correlative 

 with nutrition destroys a part of this organic matter 

 and reduces it to the condition of carbonic acid, 

 water, and salts. This constantly occurring decom- 

 position, however, not only fails to completely min- 

 eralize the substance upon which it acts, but, in addi- 

 tion, at the death of animals and plants an amount 

 of elaborated substance remains which, in future, is 

 exempt from this cause of destruction. It is here 

 that microbes or, more accurately, ferments enter on 

 the scene. 



" The life of the larger forms of vegetation builds 



