SPIRACLES OF PUP^E. 241 



in another way and both this and the preceding 

 experiment are due to the ingenious Keaumur. 

 He took the pupa of a butterfly, and suspending 

 it by a thread immersed it half way down in oil ; 

 on taking it out after some time it was still alive 

 and apparently uninjured, the reason being, that 

 the entire number of its breathing -holes were not 

 covered. He took another of the same species, 

 and plunged it entirely under the oil, and taking 

 it out after a time it was found to be quite dead ; 

 in fact it had been suffocated by the air being shut 

 out from its breathing apparatus, and that as 

 effectually as if it had been one of ourselves lying 

 at the bottom of the sea. We may say, therefore, 

 with perfect accuracy, that though the pupa, this 

 seemingly un-living object, neither moves nor 

 eats, nor in any other w r ay gives us a sign that it 

 is alive, except in a few cases, and that in its 

 advanced stages, we can, nevertheless, prove it to 

 be living ; as it can be shown that it has the power 

 of breathing ; and if it breathes, it lives. 



We may take the liberty of appropriately ap- 

 pending to this statement a most interesting and 

 delightfully-told anecdote, from the pages of the 

 Baron de Geer, of an insect whose larva lives in 



