REDI 227 



the fourth Georgic. Kedi demolished this by pointing 

 out that flies, and not bees, appear in corrupt flesh. He 

 did not however go on to explain the old belief by 

 pointing out that one flesh-haunting fly (Eristalis) is so 

 bee-like that it easily deceives an ordinary observer. 

 Pliny's statement that buried crabs produce scorpions 

 was tested, but not confirmed ; it was the same with 

 another belief drawn from Pliny, viz. that the hind legs 

 of the frog are formed by the splitting of the tail of the 

 tadpole. 



Unfortunately Redi did not trust in every case to the 

 experimental method, which he had indirectly learned 

 from Galileo ; his scientific reputation suffers by one 

 unconfirmed speculation. Having tried to explain 

 insect-galls on the supposition that they always begin 

 with an egg laid in the tissues of the plant, he was 

 perplexed by the cases in which no hole or scar showed 

 where the egg had been passed in. In order to explain 

 how a grub might occupy a nut whose shell seemed to 

 be intact, Redi threw out the suggestion that the same 

 virtue which produces flowers and fruits may also pro- 

 duce grubs, and this guess he was rash enough to 

 publish without verification. By the facile hypothesis 

 of a "vivifying principle" he explained the worms in 

 the heads of sheep and deer. One of his pupils, Vallis- 

 nieri, afterwards showed how the egg was brought into 

 the rose-gall, while Malpighi examined the young nut, 

 and found both the hole and the egg, Redi was then 

 obliged to apologise for his random guess. In spite of 

 a few unlucky mistakes he did good service by furnish- 

 ing a simple explanation of cases of propagation which 

 had been reputed mysterious. His experiments im- 

 pressed Swammerdam, Leeuwenhock and Ray, and 

 before many years had passed scientific minds at least 



