"I don't believe they will if we take good care of them," was her mother's soothing answer. "Still, we never can tell. We must heed everything Father has told us if we want to make a success of our task. To begin with there are the mulberry trees--we must not strip them of leaves too early in the season, for if we do the sap will be lost, and the strength of the tree weakened; in addition we must be careful not to waste the leaves by gathering too many at a time, or by getting the wrong kind. You know the worms will eat only freshly gathered leaves. Let us not forget that. And the young silkworms must have small and tender ones. As they grow older they will need more solid food and their development 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."