Smallpox growing virus

Viruses of vertebrates and man have not been studied nearly as well as those of the plants and bacteria mentioned. Many of them are considerably bigger The influenza virus (shown in Fig. 35 has a particle weight of 350 million the smallpox virus, several billion. These viruses contain components which are host specific and not virus specific. The introduction of tissue culture for growing virus and the use of the electron microscope for their characterization has permitted substantial progress in virus research. 

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