2 BACTERIOLOGY FOR NURSES 



teeth, and also discovered that they differed in size, 

 shape, and motility; his descriptions and plates 

 leave no doubt but what we now know as bacteria 

 were the "animalcules" which he first saw with his 

 simple lens. 



Leeuwenhoek made no attempt to formulate a 

 theory as to the place these microorganisms occu- 

 pied in nature, but his discovery of their presence 

 in water and in the intestinal evacuations led to the 

 first association of bacteria and disease in the minds 

 of medical scientists. Nothing was done at this 

 time, however, in the way of classifying or separat- 

 ing the organisms, although men did not hesitate to 

 declare them to be the cause of diseases of various 

 kinds. 



In 1762, nearly a century later, Plenciz, a Vienna 

 physician, confirmed Leeuwenhoek's discoveries, 

 and declared that to these " animalcules" was due 

 all of the infectious diseases; that the material of 

 infection must be a living substance, and endeav- 

 ored to explain upon this ground the period of incu- 

 bation. Plenciz believed that each disease was due 

 to a special germ, which was capable of multiplica- 

 tion within the human body and could be trans- 

 mitted to others. That these doctrines of Plenciz 

 should have been lost sight of seems almost incred- 



