the difcharge above mentioned, proceeding from a 
fpecies of butterfly, probably the P: urticae, which 
happened during that feafon to be uncommonly 
plentiful in the particular diftricft where the phe¬ 
nomenon was obferved. The fame idea was alfo 
entertained by Swammerdam, though he does not 
appear to have verified it from his own obfervations. 
I am the more particular on this fubject, as I 
have feen in fome author, whofe name I do not at 
prefent recolleft, this folution, and even the ap¬ 
pearance itfelf, regarded as in the higheft degree 
improbable: but the ocular atteftation of fo emi¬ 
nent a character as Peirefc, and the full perfuafion 
of a reafoner like Swammerdam, are furely fufficient 
to eftablifii not only the credibility, but the cer¬ 
tainty, both of the phenomenon itfelf and its ex¬ 
plication. 
