HABITATIONS OF INSECTS. 449 



lysed, galls are found to contain only the same princi- 

 ples as the plant from which they spring, but in a more 

 concentrated state. 



No productions of nature seem to have puzzled the 

 ancient philosophers more than galls. The commentator 

 on Dioscorides, Mathiolus, who agreeably to the doc- 

 trine of those days ascribed their origin to spontaneous 

 generation, gravely informs us that weighty prognosti- 

 cations as to the events of the ensuing year may be de- 

 duced from ascertaining whether they contain spiders, 

 worms, or flies. Other philosophers, who knew that 

 except by rare accident no other animals are to be found 

 in galls, besides grubs of different kinds which they ra- 

 tionally conceived to spring from eggs, were chiefly at a 

 loss to account for the conveyance of these eggs into the 

 middle of a substance in which they could find no ex- 

 ternal orifice. They therefore inferred that they were 

 the eggs of insects deposited in the earth, which had 

 been drawn up by the roots of trees along with .the sap, 

 and after passing through different vessels had stopped, 

 some in the leaves, others in the twigs, and had there 

 hatched and produced galls ! Redi's solution of the dif- 

 ficulty was even more extraordinary. This philosopher, 

 who had so triumphantly combated the absurdities of 

 spontaneous generation, fell himself into greater. Not 

 having been able to witness the deposition of eggs by 

 the parent flies in the plants that produce galls, he took 

 it for granted that the grubs which he found within 

 them could not spring from eggs : and he was equally 

 unwilling to admit their origin from spontaneous genera- 

 tion, an admission which would have been fatal to his 

 own most brilliant discoveries. He therefore cut the knot, 

 VOL. i. 2 G 



