try of the inhabitants. In 1849 a strange
disease, called pebrine, broke out among the worms; they were unable
to moult and died before the cocoons were spun. It spread in the
most alarming manner until, from a crop with an average of one
hundred and thirty million francs a year, the production of silk
went to less than fifty millions. The silk cultivators sent for
eggs--seed is the technical name--to Italy and Greece, and for one
season all went well. The next, the plague was as bad as ever. More
than that, it spread to Italy, Spain, Greece, and Turkey, until
Japan was the only silk-producing country where the worm was
healthy. Societies and governments, as well as individuals, were
aghast, for the silk industry of the world was on the verge of
annihilation, and every remedy the mind of man could conceive was
tried, only to be rejected. In France alone the loss in 1865 was
over one hundred million francs.

At the suggestion of Professor Dumas, the Government induced Pasteur
to examine into the "disease." He had seen in a report on the
epidemic made by M. de Quatrefages, that there were found in the
diseased worms certain minute corpuscles only to be seen under the
microscope. When in June, 1865, Pasteur arrived in the town of
Alais, he found these corpuscles without difficulty. He traced them
from the worm to the chrysalid, in the cocoon, and thence to the
moth; he found worms hatched from the eggs laid by these moths
invariably developed the corpuscles. He crushed a corpuscular moth
in water, painted a mulberry leaf with it, fed it to a healthy worm,
and the corpuscles developed. He hatched eggs from moths free from
corpuscles and secured healthy worms. While working on the
"disease," Pasteur discovered in 1867 that the mortality among the
worms was in part due to another disease, the _flacherie_, and this
he found was the result of imperfect digestion.

[Illustration: Pasteur in his Laboratory.]

_Flacherie_ was contagious, and was caused by the fermentation of the
food eaten in the body of the worm. The causes of this fermentation,
the condition of the leaves, the temperature, and others were pointed
out. As the result of five years' work, Pasteur had restored the silk
industry to its former position, and had shown that the microscopic
examination of the moth laying the eggs to be hatched was a perfect
safeguard against _pebrine_ and _flacherie_.

At the request of the emperor, Pasteur went to the Villa Vicenti