PASTEUR, KOCH, AND OTHERS 279 



tancous generation. To approach this question from the 

 experimental side was to do a great service to science. 



The experiments of Redi were simple and homely. He 

 exposed meat in jars, some of which were left uncovered, some 

 covered with parchment, and others with fine wire gauze. The 

 meat in all these vessels became spoiled, and flies, being at- 

 tracted by the smell of decaying meat, laid eggs in that which 

 was exposed, and there came from it a large crop of maggots. 

 The meat which was covered by parchment also decayed in 

 a similar manner, without the appearance of maggots within 

 it; and in those vessels covered by wire netting the flies laid 

 their eggs upon the wire netting. There they hatched, and 

 the maggots, instead of appearing in the meat, appeared on 

 the surface of the wire gauze. From this Redi concluded 

 that maggots arise in decaying meat from the hatching of 

 the eg;s of insects, but inasmuch as these animals had been 



OO ' 



supposed to arise spontaneously within the decaying meat, the 

 experiment took the ground from under that hypothesis. 



Pie made other observations on the generation of insects, 

 but with acute scientific analysis never allowed his conclusions 

 to run ahead of his observations. He suggested, however, 

 the probability that all cases of the supposed production of life 

 from dead matter were due to the introduction of living germs 

 from without. The good work begun by Redi was confirmed 

 and extended by Swammerdam (1637-1681) and Vallisnieri 

 (1661-1730), until the notion of the spontaneous origin of any 

 forms of life visible to the unaided eye was banished from 

 the minds of scientific men. 



Redi (Fig. 89) was an Italian physician living in Arentino, 

 distinguished alike for his attainments in literature and for 

 his achievements in natural science. He was medical adviser 

 to two of the grand dukes of Tuscany, and a member of the 

 Academy of Crusca. Poetry as well as other literary com- 

 positions shared his time with scientific occupations. His 



