88 PHYSIOLOGICAL ACTIVITIES 



The failure of bacteria to decompose fats rapidly is prob- 

 ably not to be ascribed to any peculiar difficulty of such 

 dissociation. It is due rather to the fact that fats generally 

 occur in Nature in rather large accumulations and hence free 

 from the elements that bacteria require for growth. The 

 elements C,H,0 are not sufficient. The other nine must 

 be available. Every buttermaker knows that thoroughly 

 washed butter keeps longer. The washing removes the 

 nitrogenous and other substances that bacteria need and 

 hence inhibits their growth. 



