At sunset the last of the laggards is back in the nest.
Now for a little arithmetic.

For seven times twenty-four hours the caterpillars have remained on the ledge of the vase.

To make an ample allowance for stops due to the weariness of this one or that and above all for the rest taken during the colder hours of the night, we will deduct one-half of the time.

This leaves eighty-four hours' walking.
The average pace is nine centimetres a minute.

(3 1/2 inches .-- Translator's Note.) The aggregate distance covered, therefore, is 453 metres, a good deal more than a quarter of a mile, which is a great walk for these little crawlers.