Pasteur thought with sorrow of the sufferings of the Cévenol populations. The scientific problem was narrowing itself down. Faced by the contradictory facts that one successful set of cocoons had produced corpuscled moths, while an apparently unsuccessful set of worms showed neither corpuscles nor spots, he had awaited the last period of these worms with an impatient curiosity. He saw, amongst those which had started spinning, some which as yet showed no spots and no corpuscles. But corpuscles were abundant in the chrysalides, those especially which were in full maturity, on the eve of becoming moths; and none of the moths were free from them. Perhaps the fact that the disease appeared in the chrysalis and moth only explained the failures of succeeding series. “It was a mistake,” wrote Pasteur (June 26, 1865), “to look for the symptom, the corpuscle, exclusively in the eggs or the worms; either might carry in themselves the germ of the disease, without presenting distinct and microscopically visible corpuscles.” The evil developed itself chiefly in the chrysalides and the moths, it was there that it should chiefly be sought. There should be an infallible means of procuring healthy seed by having recourse to moths free from corpuscles. This idea was like a searchlight flashed into the darkness. Pasteur thus formulated his hypothesis: “Every moth containing corpuscles must give birth to diseased seed. If a moth only has a few corpuscles, its eggs will provide worms without any, or which will only develop them towards the end of their life. If the moth is much infected, the disease will show itself in the earliest stages of the worm, either by corpuscles or by other unhealthy symptoms.” Pasteur studied hundreds of moths under the microscope. Nearly all, two or three couples excepted, were corpuscled, but that restricted quantity was increased by a precious gift. Two people, who had heard Pasteur ventilate his theories, brought him five moths born of a local race of silkworms and nurtured in the small neighbouring town of Anduze in the Turkish fashion, i.e. without any of the usual precautions consisting in keeping the worms in nurseries heated at an equal temperature. Everything having been tried, this system had also had its turn, without any appreciable success. By a fortunate circumstance, four out of those five moths were healthy. Pasteur looked forward to the study in comparisons that the following spring would bring when worms were hatched both from the healthy and the diseased seed. In the meanwhile, only a few of the Alaisians, including M. Pagès, the Mayor, and M. de Lachadenède, really felt any confidence in these results. Most of the other silkworm cultivators were disposed to criticize everything, without having the patience to wait for results. They expressed much regret that the Government should choose a “mere chemist” for those investigations instead of some zoologist or silkworm cultivator. Pasteur only said, “Have patience.”