308 FRAGMENTS OF SCIENCE 



quently alighting on it. The maggots, he thought, might 

 be the half-developed progeny of these flies. 



The inductive guess precedes experiment, by which, 

 however, it must be finally tested. Redi knew this, and 

 acted accordingly. Placing fresh meat in a jar and cover- 

 ing the mouth with paper, he found that, though the meat 

 putrefied in the ordinary way, it never bred maggots, while 

 the same meat placed in open jars soon swarmed with these 

 organisms. For the paper cover he then substituted fine 

 gauze, through which the odor of the meat could rise. 

 Over it the flies buzzed, and on it they laid their eggs, 

 but, the meshes being too small to permit the eggs to fall 

 through, no maggots were generated in the meat. They 

 were, on the contrary, hatched upon the gauze. By a 

 series of such experiments Redi destroyed the belief in 

 the spontaneous generation of maggots in meat, and with 

 it doubtless many related beliefs. The combat was con- 

 tinued by Vallisneri, Schwammerdam, and Reaumur, who 

 succeeded in banishing the notion of spontaneous genera- 

 tion from the scientific minds of their day. Indeed, as 

 regards such complex organisms as those which formed 

 the subject of their researches, the notion was banished 

 forever. 



But the discovery and improvement of the microscope, 

 though giving a death-blow to much that had been pre- 

 viously written and believed regarding spontaneous genera- 

 tion, brought also into view a world of life formed of in- 

 dividuals so minute so close as it seemed to the ultimate 

 particles of matter as to suggest an easy passage from 

 atoms to organisms. Animal and vegetable infusions ex- 

 posed to the air were found clouded and crowded with 

 creatures far beyond the reach of unaided vision, but per- 



