14 BACTERIOLOGY. 



ning our studies, therefore, it may be of advantage to 

 acquaint ourselves with the more prominent of these 

 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 linendraper. During his apprenticeship 

 he learned the art of lens-grinding, in which he became 

 so proficient that he eventually perfected a lens by 

 means of which he was enabled to see objects of much 

 smaller dimensions than any hitherto seen with the 

 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 diar- 

 rho3al evacuations, objects that differentiated themselves 

 the one from the other, not only by their shape and size, 

 but also by the peculiarity of movement which some of 

 them were seen to possess. In the year 1683 he dis- 

 covered in the tartar scraped from between the teeth 

 a form of microorganism upon which he laid special 

 stress. This observation he embodied in the form of 

 a contribution which was presented to the Royal So- 

 ciety of London on September 14, 1683. This paper is 



