ESSENTIALS OF BACTERIOLOGY 



INTRODUCTION 



History. The microscope was invented about the latter 

 part of the sixteenth century, and soon after, by its aid, 

 minute organisms were found in decomposing substances. 

 Kircher, in 1646, suggested that diseases might be due to 

 similar organisms, but the means at his disposal were insuffi- 

 cient to enable him to prove his theories. Anthony van 

 Leeuwenhoek, of Delft, Holland (1680 to 1723), so improved 

 the instrument that he was enabled thereby to discover 

 micro-organisms in vegetable infusion, saliva, fecal matter, 

 and scrapings from the teeth. He distinguished several 

 varieties, showed them to have the power of locomotion, and 

 compared them in size with various grains of definite measure- 

 ment. It was a great service that this "Dutch naturalist" 

 rendered the world; and he can rightly be called the " father 

 of microscopy." 



Various theories were then formulated by physicians to 

 connect the origin of different diseases with bacteria; but no 

 proofs of the connection could be obtained. Andry, in 1701, 

 called bacteria worms. Muller, of Copenhagen, in 1786, 

 made a classification composed of two main divisions monas 

 and vibrio; and with the aid of the compound microscope was 

 better able to describe them. Ehrenberg, in 1833, with still 

 better instruments, divided bacteria into four orders: bac- 

 terium, vibrio, spirillum, and spirochaete. It was not until 



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