26 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
explicit in the exact meaning they attach to the word, 
probably would not contend for a migration so instinc- 
tive as this, but in order to exhaust the question we 
must analyse all the senses in which the term can be 
employed. They probably, although not expressly, mean 
one of two things; either a quasi-instinctive tendency to 
dispersal, a blind impulse comparable to that which drives 
the Norwegian lemming ever westward into the sea, or 
else simply a quite involuntary movement caused by the 
only possible agency, namely the wind. Now touching 
the first case, 1 am far from denying that there exists. 
among many insects this quasi-instinctive tendency to 
wander. I do not however consider the example of locusts 
and ants at all to the point, because what impels these 
insects to their notorious flights and marches is simply 
the necessity for fresh food, the whole land is a wilderness 
behind them, and the question ever before their legions 
is elther starvation or a move onward; but no sane 
entomologist would I think for a moment. assert that any 
number of moths hke Devlephila gal could so exhaust 
all the nectar of all the flowers on say the Belgian coast 
that they were compelled to seek fresh woods and pastures 
new across the German ocean. 
More relevant is such an insect as the butterfly Vanessa 
cardut the well known but ill-named “painted lady,” 
rather should this be called the Ulysses of the butterflies, 
so deeply does the spirit of roaming seem to have infected 
its very nature. There is no habitable land I believe 
from New Zealand to the Arctic circle of which cardui is 
not a denizen. Usually fairly common in Europe it 
sometimes, as in 1879, appears in innumerable multitudes 
and over-runs a continent exhibiting in this character of 
occasional abundance a curious similarity to the moth 
under discussion. In this year, 1879, it appeared during 
