32 OBJECTIONS ANSWERED. 



there is good reason to believe, was introduced with some 

 foreign apple-trees. Now, extensive as is our commerce, 

 it is next to impossible, by any precautions, to prevent 

 the importation of these noxious agents. A cargo, or 

 even a sample, of peas from North America might pre- 

 sent us with that ravager of pulse, the pea-beetle (Bru- 

 chus Pi si, L.); or the famed Hessian fly, which some 

 years ago caused such trepidation in our cabinet, might 

 be conveyed here in a ship-load of wheat. Leeuwenhoek's 

 wolf (Tinea granella, F.) might visit us, in a similar con- 

 veyance, from Holland or France. But though intro- 

 duced, were Entomology a more general pursuit, their 

 presence would soon be detected, and the evil at once 

 nipt in the bud; whereas in a country where this science 

 was not at all or little cultivated, they would most pro- 

 bably have increased to such an extent before they at- 

 tracted notice, that every effort to extirpate them would 

 be ineffectual. 



It is needless to insist upon the importance of the study 

 of insects, as calculated to throw light upon some of the 

 obscurest points of general physiology ; nor would it be 

 difficult, though the task might be invidious, to point out 

 how grossly incorrect and deficient are many of the spe- 

 culations of our most eminent philosophers, solely from 

 their ignorance of this important branch of Natural His- 

 tory. How little qualified would that physiologist be to 

 reason conclusively upon the mysterious subject of gene- 

 ration, who should be ignorant of the wonderful and un- 

 looked-for fact, brought to light by the investigations of 

 an entomologist, that one sexual intercourse is sufficient 

 to fertilize the eggs of numerous generations of Aphides ! 

 And how defective would be all our reasonings on the 



