18 BACTERIOLOGY. 



serums are used successfully as preventives in many of 

 the infectious diseases and as a cure in several. An 

 acquaintance, therefore, with the main facts and results 

 of bacteriology is as necessary to the education of the 

 modern physician as a knowledge of anatomy, pathol- 

 ogy, chemistry, or any of the allied sciences. 



But before entering into a detailed consideration of 

 the subject, it may be interesting and instructive to 

 review briefly the most important steps which led up 

 to the development of the science, and upon which its 

 foundation rests, in which we shall see that the vast 

 results obtained by bacteriology were gained only 

 through long and laborious research, and after many 

 obstacles were met and overcome by indomitable per- 

 severance and accurate observation and experiment. 



The first authentic observations of living microscopi- 

 cal organisms of which there is any record are those of 

 Athanasius Kircher, in 1671. This original investi- 

 gator demonstrated the presence in putrid meat, milk, 

 vinegar, cheese, etc., of <e minute living worms," but 

 did not describe their form or character. 



Not long after this, in 1675, Anthony von Leeuwen- 

 hoek observed in rain-water putrid infusions, and in 

 his own and other saliva and diarrhoeal evacuations 

 living, motile " animalculse " of most minute dimen- 

 sions, which he described and illustrated by drawings. 

 Leeuwenhoek was a linen-draper by trade, living at 

 the time of his discoveries in Amsterdam, but he prac- 

 tised the art of lens-grinding, in which he eventually 

 became so proficient that he perfected a lens superior 

 to any magnifying glass obtainable at that day, and 

 with which he was enabled to see objects very much 

 smaller than had ever been seen before. " With the 



