SPONTANEOUS GENERATION 297 



legends, as, for example, the account in Genesis. This ques- 

 tion never can be definitely settled, even though living 

 matter should be made in the laboratory. 



The doctrine of the "spontaneous origin" of particular 

 animals or plants from dead material under man's own 

 observation is a somewhat different proposition and may be 

 subjected to experimental test. The old Greek philosophers 

 believed it. Anaximander (b. c. GlO-547) taught that some 

 animals are derived from moisture. Even Aristotle (b. c. 

 384-322) said that "animals sometimes arise in soil, in 

 plants or in other animals," i. e., spontaneously. It can be 

 stated that this belief was general from his day down through 

 the Dark and Middle Ages and later. Cardano (a. d. 1501- 

 1576) wrote that water gives rise to fish and animals and is 

 also the cause of fermentation. Van Helmont (1578-1644) 

 gives directions for making artificial mice. Kircher (1602- 

 1680) describes and figures animals iJroduced under his own 

 eyes by water on plant stems. 



However, many thinkers of the seventeenth century 

 doubted the truth of this long-established belief. Francesco 

 Redi (1626-1698) made a number of experiments which 

 tended to prove that maggots did not arise spontaneously 

 in meat, as was generally believed, but developed only when 

 flies had an opportunity to deposit their eggs on the meat. 

 It seems that by the latter part of this century the idea 

 that organisms large enough to be seen with the naked eye 

 could originate spontaneously was generally abandoned by 

 learned men. 



The w^ork of Leeuwenhoek served to suspend for a time 

 the subject of spontaneous generation, only to have it revived 

 more vigorously later on. He is usually called "The Father 

 of the Microscope," though the compound microscope was 

 invented probably by Hans Zansz or his son Zacharias, of 

 Holland, about 1590. Leeuwenhoek used a simple lens, but 

 his instruments were so much more powerful that they 

 opened up an entirely new and unknown world (Fig. 169) . 



Anthony van Leeuwenhoek (1632-1723) was apprenticed 

 to a linen draper and accumulated a comfortable fortune 

 in this business. He became interested in the grinding of 



