DISCOVERY OF BACTERIA 5 



Now Leeuwenhoek was not a scientist in the modem sense 

 of the word. That is, he did not spend his time in the lab- 

 oratory and earn his living by scientific work. No one did 

 in those days. There was no such profession open to any one 

 in the seventeenth century; and most of the advances in 

 scientific knowledge made at that time were made by monks 

 or men of leisure who dabbled in science or by men in some 

 business pursuit who were curious about nature and studied 

 its secrets in their odd moments. Thus Leeuwenhoek, besides 

 some regular trade, had a minor position in one of the pub- 

 lic buildings of Delft; in addition to all this he became 

 interested in making lenses and learned how to grind better 

 lenses than any one had before. He finally made them so 

 small and of such high magnification that it required a special 

 holder for the lens in order that he might see anything with 

 it. The lens was in the round hole near the top. The 

 platform and screw were for holding the object to be ex- 

 amined; the microscope was turned toward the light, the 

 eye placed behind the lens, and the object mounted on the 

 platform was examined (see Frontispiece). 



It seems hard to beheve that anything as small as bacteria 

 could be seen with such a crude microscope ; and yet we do 

 not know what else the objects may have been that he 

 described. Examining material scraped off the teeth, he 

 exclaimed : "With greatest surprise I saw that everywhere 

 in this material many very tiny animalcules were to be 

 found, which moved around in the most surprising fashion." 

 He noticed how abundant they were in water and com- 

 mented on the enormous number we must swallow in the 

 water we drink. His chief reaction was one of amazement 

 that there could be so many and so very small living beings. 



