2 Bacteria in Relation to Country Life 



have their specific bacterial inhabitants. There are 

 bacteria that cause abnormal conditions or "disease" 

 in plants or animals; there are others that are harm- 

 less; there are still others that are known to be dis- 

 tinctly beneficial and indispensable to the growth of 

 higher organisms. 



The existence of bacteria was not revealed until 

 the perfecting of the compound microscope, toward 

 the end of the seventeenth century. Yet, though un- 

 known as such, they made themselves manifest many 

 generations previous, by some of their activities. 

 Decay, putrefaction and fermentation were familiar 

 phenomena at the da,wn of written history. 



Contagion. — The diseases of man and of domestic 

 animals are of very ancient origin. Great epidemics 

 that devastated towns, cities, and entire kingdoms 

 were more common once than they are now. Man learned 

 long ago that disease may be spread from person to 

 person, and that personal contact increases the degree 

 of infection. So certain was this knowledge that attempts 

 were not lacking even in biblicaj/ times, and perhaps 

 earlier in old Babylonia, to establish isolation camps 

 for diseased persons, particularly in the case of lepers. 

 It will not be disputed, therefore, that not only were 

 the phenomena resulting from bacterial activities known 

 thousands of years ago, but that a certain suspicion 

 was entertained in the case of human disease that the 

 outbreak was due, in most cases,_ perhaps to some form 

 of living contagion. 



Discovery of bacteria. — Leeuwenhoek in Holland who, 

 with his more perfectly constructed lenses, first beheld 



