CHAPTER I. 



THE HISTORY OF BACTERIOLOGY. 



THE history of this science is interesting because 

 it tells how the study of bacteria developed from mere 

 theories into a science based upon facts. Long before 

 anything was known of the existence of germs, ref- 

 erences could be found in the writings o>f the ancient 

 Greeks discussing the possibility of disease passing 

 from one person to another. The agent of infection 

 was supposed to originate from the air or moisture. 



With the instruments of ancient times it was im- 

 possible to see the minute living particles which we 

 now know as germs; in fact, it is doubtful that such 

 minute forms were thought of. The seventeenth 

 century, however, marked a new era in the making 

 of optical instruments, Anthony von Leeuwenhoeck 

 in 1675, a linen draper of Amsterdam in Holland, 

 succeeded in perfecting a lens of much greater mag- 

 nifying power than those hitherto in use. By means 

 of this lens he was able to see minute living animal- 

 cules in saliva, water, and other fluids, that were 

 smaller than any seen before. The descriptions of the 

 animalcules he saw were very accurate and correspond 

 to some of the forms we recognize today. 



The discovery of these minute living organisms The theory 



provoked a great deal of discussion, as may be 

 imagined. Perhaps the question most debated was tion 



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