436 



EXTINCTION OF SPECIES. 



[Ch. XLII. 



some 



enmi 



Scarcely any beast^ observes Linnseus^ will toucli the nettle, 

 but fifty different kinds of insects are fed by it.-^ Some of 

 these seize upon the root, others upon the stem ; some eat 

 the leaves 5 others devour the seeds and flowers : but for this 

 multitude of enemies, the nettle {Urticc 

 hilate a great number of plants. The 



would anni- 



same 



us, in his ' Tour in Scania/ that goats were turned into an 

 island which abounded with the Agrostis arundinacea^ where 



famine 



grew fat on the same plant. The goat, also, he says, thrives 

 on the meadow-sweet and water-hemlock, plants which are 



t 



^f 



Wilcke 



proper insect allotted to it to curb its luxuriancy, and to 

 prevent it from multiplying to the exclusion of others. 

 ' Thus grass in meadows sometimes flourishes so as to exclude 

 all other plants : here the Phalcena graminis {Bombyx gram.)^ 

 with her numerous progeny, finds a well-spread table 5 they 

 multiply in immense numbers, and the farmer, for some 

 years, laments the failure of his crop ; but, the grass being 

 consumed, the moths die with hun 

 place. Now the quantity of grass 

 the other plants, which were before choked by it, spring up, 

 and the ground becomes variegated with a multitude of diffe- 

 rent species of flowers. Had not Nature given a commission 

 to this minister for that purpose the grass would destroy a 



number 



t 



made 



mitted in 1 740, and the two following years, in many provinces 

 of Sweden, by a most destructive insect. The same moth is 

 said never to touch the foxtail grass, so that it maybe classed 

 as a most active ally and benefactor of that species, and as 

 peculiarly instrumental in preserving it in its present abun- 

 dance. § A discovery of Eolander, cited in the treatise of 



^"- Amoen. Acad., vi. p. 17, § 12. 

 t Ibid. vol. vii. p. 409. 



t Ibid. vol. vi. p. 17, § 11, 12. 

 Kirby and Spence, vol. i. p. 178. 



