velopment will keep pace with the advancing vegetation. It is the
saccharine they take from the leaf that makes them grow; if you feed
them tough leaves with little saccharine in them the poor worm has all
the labor of eating a vast quantity of material that simply takes its
strength and leaves it exhausted and unnourished. Of course we have
plenty of leaves to choose from and we shall not need to economize our
supply of food. But where people grow silk in great quantities they
calculate very closely, and plan to get the greatest number of pounds of
silk from the smallest possible number of leaves. That is the way all
professional silk-growers work. Paying their leaf-gatherers is quite an
expense, and they do not wish this item needlessly large. They buy the
leaves by weight, and the leaf purchasers soon become expert in
selecting those lots that are the most nutritious; for every one wants
his silkworms to grow large and strong so that they may spin fine
cocoons and give out a valuable quality of silk."

"Why, Mother, just feeding them is an absolute science in itself then,"
sighed Pierre in dismay. "I thought if we kept them from going hungry it
was all we had to do. We never shall be wise enough to work out such a
problem as you have put to us."

"It is not to be expected that we shall," replied his mother kindly.
"Such scientific treatment of silkworms takes both knowledge and
experience. Many people raise a good crop of cocoons without knowing
much more than we do--sometimes not as much. I was only telling you the
possibilities of the industry if one were to pursue it on a large scale.
If you and Marie and I keep our silkworms alive, clean, and well-fed,
and reap a reasonable harvest of cocoons, we must be satisfied. I shall
consider we have done well. Only let us not waste more leaves than we
must. In time we shall learn to estimate about how many to gather at a
picking. Fortunately here in France the mulberry trees yield more leaves
than they do in most countries, so I am not worried lest we fall short.
In some countries the number of leaves is very limited, and the
gatherers are compelled to be exceedingly careful not to waste them. I
remember hearing your father say that in Persia, where the climate is
very hot, the natives gather small branches of leaves, that they may be
fresher than they would be if picked one at a time."

"Why don't we do that here?" inquired Marie. "I should think it would be
a fine plan