The life of the population of certain departments in the South of France hangs on the existence of silkworms. In each house there is nothing to be seen but hurdles, over which the worms crawl. They are placed even in the kitchens, and often in well-to-do families they occupy the best rooms. In the largest cultivations, regular stages of these hurdles are raised one above the other in immense sheds, under roofs of disjointed tiles, where thousands and thousands of silkworms crawl upon the litters which they have the instinct never to leave. Great or small, the silkworm-rearing establishments exist everywhere. When people accost each other, instead of saying 'How are you?' they say 'How are the silkworms?' In the night they get up to feed them or to keep up around them a suitable temperature. And then what anxiety is felt at the least change of weather! Will not the mulberry leaves be wet? Will the worms digest well? Digestion is a matter of great importance to the health of the worms, which do nothing all their lives but eat! Their appetites become especially insatiable during the last days of rearing. All the world is then astir, day and night. Sacks of leaves are incessantly brought in and spread out on the litters. Sometimes the noise of the worms munching these leaves resembles that of rain falling upon thick bushes. With what impatience is the moment waited for when the worms arrive at the last moulting! Their bodies swollen with silk, they mount upon the brambles prepared for them, there they shut themselves up in their golden prisons and become chrysalides. What days of rejoicing are those in which the cocoons are gathered; when, to use the words of Olivier de Serres, the silk harvest is garnered in! Just as in all agricultural harvests, this ingathering of the silk is exposed to many risks. Nearly always, however, it pays the cultivator for his trouble, and sometimes pays him largely. But in 1849, after an exceptionally good year, and without any atmospheric conditions to account for the fact, a number of cultivations entirely broke down. A disease which little by little took the proportions of an epidemic fell upon the silkworm nurseries. Worms hardly hatched, and worms arrived at the last moulting, were equally stricken in large numbers. It mattered little in what phase the silkworm happened to be: in all it was assailable by the evil.