HABITATIONS OF INSECTS. 255 



ence, though mentioned by Tacitus, Strabo, and Josephus, has been 

 questioned by Riland, Maundrell, and Shaw, and respecting which nu- 

 merous contradictory and erroneous opinions by more recent authors 

 have been collected by Mr. Conder in his Modern Traveller, have at length 

 had their true history developed by the late venerable vice-president of 

 the Linnean Society, A. B. Lambert, Esq. 1 , Walter Elliot, Esq., and 

 J. O. Westwood, Esq. 2 From their combined observations, it has been 

 ascertained that the Poma Sodomitica are actual galls, two inches long and 

 an inch and a half in diameter, of a beautiful rich glossy purplish red ex- 

 teriorly, and filled with an intensely bitter, porous, and easily pulverised 

 substance, surrounding the insect (Cynips insana Westwood), which has 

 given birth to them, and were found by Mr. Elliot growing on various 

 species of dwarf oaks beyond the Jordan and in the Troad, to the twigs of 

 which Mr. Westwood remarks they are attached in a curious manner, 

 unlike what he has seen in any other galls, the narrow end "rising 

 upwards on each side and bending inwards, so as to clasp the extremity 

 of the twig somewhat like a pair of wide and curved nippers." 



How the mere insertion of an egg into the substance of a leaf or twig, 

 even if accompanied, as some imagine, by a peculiar fluid, should cause 

 the growth of such singular protuberances around it, philosophers are as 

 little able to explain as why the insertion of a particle of variolous matter 

 into a child's arm should cover it with pustules of small pox. In both 

 cases the effects seem to proceed from some action of the foreign sub- 

 stance upon the secreting vessels of the animal or vegetable : but of the 

 nature of this action we know nothing. Thus much is ascertained by the 

 observations of Reaumur and Malpighi that the production of the gall, 

 which, however large, attains its full size in a day or two 3 , is caused by 

 the egg or some accompanying fluid ; not by the larva, which does not 

 appear until the gall is fully formed 4 : that the galls which spring from 

 leaves almost constantly take their origin from nerves 5 ; and that the egg, 

 at the same time that it causes the growth of the gall, itself derives 

 nourishment from the substance that surrounds it, becoming considerably 

 larger before it is hatched than it was when first deposited. 6 When che- 

 mically analysed, galls are found to contain only the same principles as the 

 plant from which they spring, but in a more concentrated state. 



No productions of nature seem to have puzzled the ancient philo- 

 sophers more than galls. The commentator on Dioscorides, Mathiolus, 

 who agreeably to the doctrine of those days ascribed their origin to spon- 

 taneous generation, gravely informs us that weighty prognostications as 

 to the events of the ensuing year may be deduced 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 rationally 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 

 external 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 



1 Linn. Trans, xvii. 445. 2 Trans. Ent. Soc. Lond. ii. 16. 



3 Reaum. iii. 474. * Ibid. 479. 



5 Ibid. 501. 6 ibid. 479. 



