Cardboard, flannel, dust, sand, and porous objects retained it longest.

Metals, marble, and glass, on the contrary, quickly lost their efficacy.

Finally, anything on which the female had rested communicated its virtues by contact; witness the butterflies crowding on the straw-bottomed chair after the twig fell to the ground.
Using one of the most favourable materials--flannel, for example--I witnessed a curious sight.

I placed a morsel of flannel on which the mother moth had been lying all the morning at the bottom of a long test-tube or narrow-necked bottle, just permitting of the passage of a male moth.

The visitors entered the vessels, struggled, and did not know how to extricate themselves.