278 THE FLOATING-MATTER OF THE AIR. 



spontaneous generation which would now be rejected 

 as monstrous by the most fanatical supporter of the 

 doctrine. Shell-fish of all kinds were considered to 

 be without parental origin. Eels were supposed to 

 spring spontaneously from the fat ooze of the Nile. 

 Caterpillars were the spontaneous products of the leaves 

 on which they fed ; while winged insects, serpents, rats, 

 and mice were all thought capable of being generated 

 without sexual intervention. 



The most copious source of this life without an 

 ancestry was putrefying flesh ; and, lacking the checks 

 imposed by fuller investigation, the conclusion that 

 flesh possesses and exerts this generative power is a 

 natural one. I well remember when a child of ten or 

 twelve seeing a joint of imperfectly salted beef cut into, 

 and coils of maggots laid bare within the mass. 

 Without a moment's hesitation I jumped to the con- 

 clusion that these maggots had been spontaneously 

 generated in the meat. I had no knowledge which 

 coidd qualify or oppose this conclusion, and for the 

 time it was irresistible. The childhood of the indi- 

 vidual typifies that of the race, and the belief here 

 enunciated was that of the world for nearly two thou- 

 sand years. 



To the examination of this very point the celebra- 

 ted Francesco Eedi, physician to the Grand Dukes 

 Ferdinand II. and Cosmo III. of Tuscany, and a 

 member of the Academy del Cimento, addressed him- 

 self in 1668. He had seen the maggots of putrefying 

 flesh, and reflected on their possible origin. But he 

 was not content with mere reflection, nor with the 

 theoretic guesswork which his predecessors had founded 

 upon their imperfect observations. Watching meat 

 during its passage from freshness to decay, prior to the 

 appearance of maggots he invariably observed flies 



