SPONTANEOUS GENERATION 85 



forms is a very old one. Formerly, caterpillars 

 were supposed to arise spontaneously from leaves; 

 and frogs, fishes, and eels were said to be produced 

 from mud and ooze. Virgil has described how bees 

 arise from the carcass of a dead bull, and Van 

 Helmont, although a scientist of eminence, tells us 

 that mice may be engendered by putting some dirty 

 linen in a container along with a few grains of 

 wheat. 



The first to perform real experiments in regard 

 to the origin of living things was Francesco Redi, 

 physician to the Grand Dukes of Tuscany. Re- 

 flecting on the origin of the maggots observed in 

 decaying meats, he set himself to trace their source. 

 Noticing that blowflies frequently hovered about, 

 and often alighted on, decaying meat, he thought 

 that these flies might possibly be responsible, in 

 some way, for the appearance of the maggots. 

 Accordingly, he placed pieces of meat in jars cov- 

 ered with gauze to exclude the flies. Although the 

 meat so protected was found to putrefy, no mag- 

 gots made their appearance. Moreover, Redi ob- 

 served that the flies laid eggs, and that from these 

 eggs small maggots arose which grew rapidly as 

 they devoured the decaying flesh. By many obser- 

 vations and experiments, Redi conclusively showed 



