4o C.C. NATURAL HISTORY SOCIETY. 



The next question is — How do microbes act ? 



Firstly, they are nature's scavengers. Wherever dead vegetable 

 or animal matter exists there they assemble in their millions, breaking 

 down the complex organic compounds into simpler ones, which can 

 again be usefully taken up by other plants or animals. 



The true key to the answer as to how the microbe acts is found 

 in the fermentation by yeasts. Of yeasts there are different kinds, 

 and the difference between the beers of England, Scotland and North 

 Germany, and that of South Germany and Austria, which we know 

 as Lager beer, is due to the difference in the yeast. In the former 

 an organism growing at a high temperature and forming a frothy scum 

 at the surface is the active agent ; in the latter a bottom growing 

 yeast, which thrives independently of air and at a low temperature, 

 brings about similar changes but with different results, less alcohol 

 being formed and a more delicate flavour. 



Of ferments due to microbes there are no end. The conversion 

 of alcoholic liquors into vinegar is due to one microbe, the souring of 

 milk is due to another, while the turning butter rank and cheese ripe 

 are also effects of microbes. 



Having thus learned something about the manner of the microbe, 

 we can understand better the aims of those who are now working at 

 the diseases some of them cause. It had long been common in the 

 East to inoculate small-pox virus in order to protect the patient from 

 a more serious attack, but Lady Wortley Montagu, after submitting 

 her own child to the operation in 1718, introduced the practice into 

 Europe, where it became common till it was found that small-pox 

 was being spread in all directions from those who had been inoculated 

 and gained for themselves protection. It was then that Jenner, 

 having heard that persons who had caught cow-pox while milking and 

 were protected from small-pox, took the hint and by experiment 

 convinced himself of the country-side tradition. And we are now 

 with a fuller knowledge following along the direction pointed out by 

 Jenner more than a hundred years ago. 





