20 



Microbes and You 



light-type microscopes and explains why we can't just keep setting 

 up stronger and greater numbers of lenses to raise magnifying 

 powers of the instruments. When we employ light of shorter 

 wavelength, such as ultra-violet light, as our source of illumina- 



I 



■,w 



Fig. 6. Universal type electron microscope. (Courtesy of Radio 

 Corporation of America, RCA Victor Division, Camden, New Jersey.) 



tion, we can increase the magnifying power about two or three 

 times that of ordinary light instruments. However, even with 

 ultra-violet light we are unable to photograph these particles which 

 we now call viruses. 



