GLOSSARY 211 



Vaccine Originally used for the inoculation of cowpox as a 

 protective agaiAst smallpox; now used for that and for the injection 

 of dead or attenuated bacteria for active immunization or treatment 

 during disease. See Bacterins. Related words: to vaccinate, 

 vaccination. 



Viable Capable of living and reproducing. 



Virulence The power possessed by organisms to develop poisons 

 and produce disease. It varies in different strains, but depends also 

 upon the resistance of the host. 



Virus Any factor which produces disease, either individually 

 recognized or obscure; usually applied to poisons not specifically 

 isolated, like rabies virus. 



