REASON FOR CHEMICAL BREAKDOWN OF ENVIRONMENT 9 



the formation of acid end-products and a consequent fall in 

 the pH of the medium, which may be of such dimensions as 

 to steriUse the activities of the growing organism ; under such 

 conditions some organisms are capable of catalysing neutralisa- 

 tion reactions which either have alkaline end-products or 

 result in the alteration of acid products to neutral ones, so 

 that some degree of stabilisation of the internal environment 

 is accomplished. The organisms therefore attack their 

 environment to obtain material for growth, energy for 

 synthesis, and stabilisation against unfavourable conditions. 



