Microbiology Takes fbe Stage 203 



We have come a long way during these last few decades. 

 There is no field of human endeavor where microbes are 

 not recognized now as playing an important, and fre- 

 quently a dominant, part. We can now recognize, utilize, 

 combat, and in most cases control the numerous microbes 

 that cause infectious diseases and epidemics, that attack 

 our animals and our plants, that destroy our food supplies 

 and our clothing, that inhabit our soils and our seas, the 

 air we breathe, the water we drink, and even our bodies. 

 We also have learned to know microbes as complex living 

 systems. We now understand better their growth and their 

 functions, their manner of multiplying, and of utilizing 

 simple and complex nutrients, and we have gained con- 

 siderable information concerning the complex biochemical 

 reactions involved in these processes. 



We have learned much about the life of microbes in 

 pure cultures and in complex populations, and about the 

 production by many of them of specific chemical sub- 

 stances which stimulate or inhibit the growth of others. 

 We have learned also to utilize such substances for im- 

 proving and accelerating the growth of higher forms of 

 life, for destroying injurious microbes, thus improving 

 human and animal health. Diseases and epidemics that 

 formerly decimated huge segments of the world's popu- 

 lation have now been brought under control, deaths due to 

 diseases of childhood are now relatively rare, and the life 

 span of man has been greatly extended. 



How has all this been brought about? What have we 

 learned that will help us to plan our future investigations? 

 To what extent has the microbiologist benefited from the 

 contributions of the general biologist? In what respects do 

 the methods of studying bacteria, fungi, actinomycetes, and 

 protozoa differ from the methods of studying higher forms 

 of life, both plant and animal? Are the tools, the methods, 

 the approaches, or observations used in the study of mi- 

 crobes different from those employed by the general bi- 

 ologist? 



