Historical 3 



biology." These sciences are based on the appHcation and practical 

 utilization of the activities of microorganisms. They also deal with 

 the cycle of life in nature, notably the numerous decomposition 

 processes whereby microorganisms liberate products that are useful 



Fig. 1. Sir John Lawcs established the Rothamsted Experimental Station, in 

 which the most continuous experimental studies on soil fertility have been car- 

 ried out for more tlian a century. Some of the fundamental studies of the 

 microorganisms of the soil have been carried out at that institution. 



or even essential for the growth of plants and animals. The knowl- 

 edge thus gained has revolutionized many agricultural practices and 

 has contributed to the discovery of many new processes, ranging from 

 industrial fermentations to the manufacture of chemotherapeutic or 

 disease-combating agents. 



Pasteur established the fact that the mechanism of decomposition 

 of organic matter by microorganisms depends not only upon the 

 natiu'e of the organisms but also upon the environmental conditions 

 under which the process is taking place. In the presence of oxygen, 



