10 POPULAR ERRORS. 



Francesco Redi, an Italian physician, seems to 

 have been the first to discover (in 1668), what it 

 now seems difficult to believe that anybody could 

 have ever failed to observe, that the maggots found 

 in putrefying meat were not a direct product of 

 putrefaction, but came from eggs deposited by flies. 

 He proved this to the doubting people of his time by 

 placing some meat in jars having gauze over the 

 top, when the meat within the jars decayed as 

 usual, but contained no maggots. 



During the revival of learning, at the close of the 

 Middle Ages, the belief in spontaneous generation 

 gradually died out. Upon the invention of the micro- 

 scope, however, and the discovery of low forms of life, 

 the existence of which were before unknown, it came to 

 be believed by scientific men that these organisms 

 were exceptions to the general rule, for it was seen 

 that wherever suitable conditions for their growth 

 existed they made their appearance. 



Pasteur of France, who is still living, undertook, 

 almost unaided, to refute this opinion, and suc- 

 ceeded so well that his results have been accepted 

 throughout the scientific world. Students of fungi, 

 bacteria, and other microscopic plants and animals, 

 now take it for granted that wherever any of these 

 organisms appear it is conclusive evidence that 

 there were previously present germs of the same 

 kind. 



