CHAPTER 22 



Viruses 



BRIEF HISTORICAL REVIEW OF VIRUSES 



CLASSIFICATION 



CHARACTERISTICS OF VIRUSES 



TECHNICS FOR CULTIVATION 

 Tissue culture 

 Fertile eggs 



DISEASES 

 Of bacteria 

 Of plants 

 Of animals 



IMMUNITY TO VIRUS DISEASES 



DIAGNOSTIC PROCEDURES 



BRIEF HISTORICAL REVIEW 



With the discovery of bacteria man felt that he had found the 

 simplest forms of life— that last step between living and dead 

 matter. But when Iwanowski in 1892 demonstrated that the sap 

 from a diseased plant could be passed through the finest porcelain 

 filters and the filtrate Vv^as capable of transmitting the disease to 

 healthy susceptible plants, the concept of the smallest living thing 

 had to be re-evaluated. The filterable agent, too small to be seen 

 under ordinary compound microscopes, was called a virus, a word 

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