212 MICROBES, FERMENTS, AND MOULDS- 



It may be useful to retrace here the curious history 

 of vaccine, since it is directly interesting to us all. 







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FiK 91 Section of skin covering a small-pox pustule : a, horny layer of the 

 epidermis; d, adenoid tissue-; TO, m, micrococci stained with methyl violet (x 

 850 diam.). 



Before vaccine was discovered, inoculation with 

 small -pox was practised as a preventive measure. 



