To end this academic episode, we will quote from Joseph Bertrand’s letter of thanks to Pasteur, who had sent him the article: “...The public will learn, among other things, that the eminent members of the Academy admire and love each other sometimes with no jealousy. This was rare in the last century, and, if all followed your example, we should have over our predecessors one superiority worth many another.”
Thus Pasteur showed himself a man of sentiment as well as a man of science; the circle of his affections was enlarging, as was the scope of his researches, but without any detriment to the happy family life of his own intimate circle. That little group of his family and close friends identified itself absolutely with his work, his ideas and his hopes, each member of it willingly subordinating his or her private interests to the success of his investigations. He was at that time violently attacked by his old adversaries as well as his new contradictors. Pouchet announced everywhere that the question of spontaneous generation was being taken up again in England, in Germany, in Italy and in America. Joly, Pouchet’s inseparable friend, was about to make some personal studies and to write some general considerations on the new silkworm campaign. Pasteur, who had confidently said, “The year 1867 must be the last to bear the complaints of silkworm cultivators!” went back to Alais in January, 1867. But, before leaving Paris, Pasteur wrote out for himself a list of various improvements and reforms which he desired to effect in the administration of the Ecole Normale, showing that his interest in the great school had by no means abated, in spite of his necessary absence. He brought with him his wife and daughter, and Messrs. Gernez and Maillot; M. Duclaux was to come later. The worms hatched from the eggs of healthy moths and those from diseased ones were growing more interesting every day; they were in every instance exactly what Pasteur had prophesied they would be. But besides studying his own silkworms, he liked to see what was going on in neighbouring _magnaneries_. A neighbour in the Pont Gisquet, a cultivator of the name of Cardinal, had raised with great success a brood originating from the famous Japanese seed. He was disappointed, however, in the eggs produced by the moths, and Pasteur’s microscope revealed the fact that those moths were all corpuscled, in spite of their healthy origin. Pasteur did not suspect that origin, for the worms had shown health and vigour through all their stages of growth, and seemed to have issued from healthy parents. But Cardinal had raised another brood, the produce of unsound seed, immediately above these healthy worms. The excreta from this second brood could fall on to the frames of those below them, and the healthy worms had become contaminated. Pasteur demonstrated that the pébrine contagion might take place in one or two different ways: either from direct contact between the worms on the same frame, or by the soiling of the food from the very infectious excreta. The remedy for the pébrine seemed now found. “The corpuscle disease,” said Pasteur, “is as easily avoided as it is easily contracted.” But when he thought he had reached his goal a sudden difficulty rose in his way. Out of sixteen broods of worms which he had raised, and which presented an excellent appearance, the sixteenth perished almost entirely immediately after the first moulting. “In a brood of a hundred worms,” wrote Pasteur, “I picked up fifteen or twenty dead ones every day, black and rotting with extraordinary rapidity.... They were soft and flaccid like an empty bladder. I looked in vain for corpuscles; there was not a trace of them.”