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 organ- 

 isms, but the means at his disposal were insufficient 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 microorganisms 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 measurement. 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. Miiller, 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 



