304 VEGETABLE PHYSIOLOGY 



There are other plants however which are incapable 

 of carrying on their life in the presence of oxygen. They 

 are of a very humble type, and occur only among the 

 Bacteria and Fungi. An instance may be found in the 

 organisms which induce the formation of butyric acid from 

 sugar or lactic acid. If a few of these are sown in a 

 suitable liquid, and this is then enclosed in a hermetically 

 sealed flask from which free oxygen has been removed, 

 they multiply with extreme rapidity, until indeed either 

 their food supply is exhausted, or the waste products of 

 their metabolism accumulate to an inhibitory extent. If a 

 little free oxygen is admitted their activity ceases and 

 death ensues, or they pass into a resting condition, which 

 lasts as long as oxygen is present. 



