14 BACTERIOLOGY. 



butions 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 development, many obser- 

 vations were made which formed the foundation work 

 for much that was to follow. Before regularly begin- 

 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 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 

 diarrhoaal evacuations, objects that differentiated them- 

 selves 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 



