STRUCTURE OF PUPiE. -97 



some idle doctor, cooped up in his study, lias in- 

 vented, that conduce nothing to the ease and happi- 

 ness of lile, and iiom whicli he expects no other ad- 

 vantage unless tliat of reaping so much the greater 

 har\'est of empty glory from his arguments; as they 

 contain less of truth and common sense, on account 

 of the extraordinary strength of genius and applica- 

 tion requisite to give an imposing air to such ab- 

 surdities.' 



It was the decided opinion of Swammerdam that 

 tlie several transformations of insects, particularly the 

 change from the egg to the cateri)illar, and from the 

 pupa to the perfect insect, are chietly etlected by the 

 evaporation of the superabundant fluids. Thus he 

 tells us that the nit, or egg of the louse {Pcdiculiis 

 hiimanus), is nothing more than the insect itself, 

 which only requires the evaporation of the surround- 

 ing moisture and the casting of the old skin, to bring 

 it to its i)erfect form.* It is not a little surprising 

 that so very accurate a naturali^■t should never have 

 thought of investigating the truth of such an opinion 

 by experiment. That he neglected this precaution, is 

 an instance, among thousands n)ore, of the imperfec- 

 tion of human studies; for his very first trial would 

 have demonstrated the error, which pervades every 

 page of his great work. He was evidently misled 

 into the opinion by perceiving how fluid the contents 

 of an egg or of a pupa are when opened previous to 

 their change, and how dry the insect is upon its 

 evolution. 



It is much more surprising to find Kirby and 

 Spence repeating the same, or nearly the same opi- 

 nion, at the very time, too, when they are in the act 

 of quoting tlie experiments of Rt'aumur, by which it 

 is retiited, though the great experimenter himself mis- 

 interpreted (hem. ' If you open a pupa,' say they, 



t^waniiiierdiiii, ptis!>iiti. 



