18 BACTERIOLOGY 



medicine. Though the contributions which have done most 

 to place bacteriology on the footing of a science are those 

 of recent years, still, during the earlier stages of its devel- 

 opment, many observations were made which formed the 

 foundation-work for much that was to follow. Before 

 regularly beginning our studies, therefore, it may be of 

 advantage to acquaint ourselves with the more prominent 

 of those investigations. 



Antony van Leeuwenhoek, the first to describe the bodies 

 now recognized as bacteria, was born at Delft, in Holland, 

 in 1632. He was not considered a man of liberal education, 

 having been during his early years an apprentice to a linen- 

 draper. During his apprenticeship he learned the art of 

 lens-grinding, in which he became so proficient that he 

 eventually perfected a simple lens by means of which he was 

 enabled to see objects of much smaller dimensions than 

 any hitherto seen with the best compound microscopes in 

 existence at that date. At the time of his discoveries he 

 was following the trade of linendraper in Amsterdam. 



In 1675 he published the fact that he had succeeded in 

 perfecting a lens by means of which he could detect in a 

 drop of rain-water living, motile "animalcules" of the most 

 minute dimensions — smaller than anything that had hitherto 

 been seen. Encouraged by this discovery, he continued to 

 examine various substances for the presence of what he 

 considered animal life in its most minute form. He found 

 in sea-water, in well-water, in the intestinal canal of frogs 

 and birds, and in his own diarrheal evacuations, objects 

 that differentiated themselves the one from the other, 

 not only by their shape and size, but also by the peculiarity 

 of motility which some of them were seen to possess. In the 

 year 1683 he discovered in the tartar scraped from between 



