PAPILIONID^ — BUTTERFLIES. 225 



taken up part of an animal, which was in a state of decom- 

 position, and have brought it in contact with an electric 

 cloud, in which it was kept in a state of partial fluidity or 

 vicosity. In this case, the cloud which was seen by the ne- 

 groes, as the state in which the materials were, is accounted 

 for." 



Prof. Troost published this profound solution in the forty- 

 first volume of Silliman's Journal ; but in the forty-fourth 

 of the same magazine a much more satisfactory one is given, 

 for it is there stated " that the whole affair was a hoax de- 

 vised by the negroes, who pretended to have seen the shower 

 for the sake of practicing on the credulity of their masters. 

 They had scattered the decaying flesh of a dead hog over 

 the tobacco leaves."^ 



Another phenomenon to be particularly noticed in the 

 history of the Butterflies, is their appearance at certain 

 times in countless numbers migrating from place to place. 

 II. Kapp, a writer in the Naturfoi^sch, observed on a calm 

 sunny day a prodigious flight of the Cabbage-Butterfly, 

 Fontia hrassicde, which passed from northeast to south- 

 west, and lasted two hours.^ Kalm, the Swedish traveler, 

 saw these last insects midway in the British Channel.^ 

 Lindley tells us that in Brazil, in the beginning of March, 

 1803, for many days successively there was an immense 

 flight of white and yellow Butterflies, probably of the same 

 tribe as the Pontia brassicas. They were observed never to 

 settle, but proceeded in a direction from northwest to south- 

 east. 'No buildings seemed to stop them from steadily pur- 

 suing their course ; which being to the ocean, at only a 

 small distance, they must all have inevitably perished. It is 

 to be remarked that at this time no other kind of Butterfly 

 was to be seen, though the country usually abounds in such 

 a variety.* 



A somewhat similar migration of Butterflies w^as ob- 

 served in Switzerland on the 8th or 10th of June, 1828. 

 The facts are as follows : Madame de Meuron Wolff and 

 her family, established during the summer in the district of 



1 Sil. Journ., xli. 403-4, and xliv. 216. 



2 JVaiurforsch, xi. 94. 



3 Travels, i. 13. 



^ Royal Milit. Chron. for March, 1815, p. 452. K. and S. Introd. 

 ii. 11. 



20* 



