From a peg over the fireplace she took down a key, and going out, crossed the lawn to a building which stood opposite. The children danced after her, entering the silent structure with prancing steps. Once inside, however, they stopped their skipping as if automatically and instead began creeping softly about on their tiptoes. Then Pierre glanced up and laughed. "I declare if we are not as quiet as though the silkworms were here already," said he. His mother smiled. "It is force of habit," she answered. "We always have to be so quiet when they are here that it is hard to remember there is no need for the precaution when the building is empty. How odd it is that their hearing should be so acute! No one who has not had the care of silkworms can realize the disastrous results of startling them." "Father once told me he had known of a lot of silkworms that stopped eating and died because a sudden noise frightened them," observed Pierre. "Such a calamity is not at all unusual, Pierre," returned his mother. "And more than that, if anything alarms them after they have begun to spin they will frequently snap the thread of their cocoon and refuse to spin any more; if they do continue the interruption causes a lump, or rough place, in the filament so that it is imperfect and has to be broken and tied. In consequence the silk is poorer and brings a lower price. So you see how really important it is not to jar their sensitive nerves." "Who would think that one of those green caterpillars had any nerves!" ventured Marie. "Is it true, Mother, that a thunder-storm will check their spinning?" "Yes. It often does if the thunder is very heavy. Your father once lost an entire crop of silkworms because of a severe thunder-storm. The little creatures died of fright. It is wonderful how delicately attuned they are." "And their sense of smell is so keen," Marie continued thoughtfully. "I remember one day Father hurried me out of the silk-house because I had some perfume on my handkerchief. I was so cross," she added with a shamefaced little flush, "for I thought the perfume very nice and I couldn't understand why he did not like it." "Miss Vanity!" cried Pierre. "I guess afterward you saw he was dead right. He couldn't take the chance of losing his silkworms, and I don't blame him, either. It is far too much work to raise them; isn't it, Mother?" "I rather think you will say so when you have raised your own crop," was the quiet answer. "Do you remember the Italian Father hired to help him once; and how he afterward sent the man away because he would smoke, and smelled of tobacco all the time?" "Yes. That was another example of the same thing," replied Madame Bretton. "Your father was afraid to risk keeping the man. The caterpillars might scent the tobacco and object to it." "I had no idea they were so fussy!" gasped Marie. "I do hope our silkworms won't get frightened and die, or else have something make them stop spinning."