EPHEMERA. 183 
At length the destined time comes, the 
perfect fly rises to the surface of the 
water, disengages itself from the nymph 
skin, and instantly darts away. 
Lucy, I should like greatly to see 
them at that moment. 
Mother, This process generally takes 
place in the evening, or during the 
night ; each species having its fixed hour 
for changing. Those belonging to the 
river Seine, in France, change in the be- 
ginning of August, between nine and 
eleven at night ; while those of the Rhine, 
in Germany, take wing about two hours 
before sunset. In some parts of Germany 
their numbers are so prodigious, that they 
are used by the gardeners as manure. 
Lucy. But how can they catch such 
swift little creatures r 
Mother. Several kinds of them live 
but three hours-; some but a single 
day ; and even the most long-lived spe- 
cies only for three days. As they have 
no time for eating, so they are unpro- 
vided with a mouth, or any mode of ob- 
