. The sap which results
from these leaves, when subjected to a heavy pressure, is of a greenish
tinge, and sometimes even colorless; it does not become blue until after
fermentation in the open air. The Indians then boil it in an immense
copper, and, the water evaporating, the indigo is left in the form of a
soft and gelatinous paste, which is subsequently dried in the sun."

On approaching the foot of the mountain, I found that it would be
impossible for us to climb it the next day, the slope being too steep. I
sat down on the trunk of a fallen tree, when I detected a very decided
smell of roses. Under the bark of a log _esquina_ Lucien had discovered
five or six beautiful insects of an azure-blue color, with red feet;
these insects are very common in the sandy soils of Tehuacan, and are
used by the ladies of that district to perfume their linen. Delighted at
this discovery, Lucien continued his search, hoping to find some more
specimens which he intended to take to his mother. He was kneeling down
and working energetically, when he pointed out to me an enormous
caterpillar.

It was of an emerald-green color, and had on its back a row of little
projections like small trees, symmetrically arranged. These were of a
brilliant red, terminating in shoots the same color as the animal's
body.

"What a curious creature!" cried Lucien; "it looks as if it carried a
garden on its back; what use are all these bushes?"

"It is not known, and it is a curious fact that the butterfly which
springs from the caterpillar shows no trace of all this
strangely-arranged hair."

"Will a butterfly come from this caterpillar?"

"Yes, certainly; all butterflies lay eggs, from which proceed
caterpillars, which generally destroy the plants on which they are
hatched. When arrived at maturity, the caterpillar spins a cocoon of
silk, more or less fine, in the centre of which it incloses itself. It
is then called a _chrysalis_. In this cocoon the butterfly is formed,
either white or black, yellow or green, and there it remains inactive
and imprisoned, like a baby in swadding-clothes. In spring it perforates
its silken prison, and soon makes its escape a splendid butterfly,
subsisting upon the juices of the flowers obtained through its
proboscis. Surely you were not ignorant of all these transformations?"

"I thought that they only took place in silk-worms."

"Well, now you are undeceived; all caterpillars and all butterflies are
subject to t