What has been said of the influence and cooperation of the women already named may, with equal truth, be affirmed of numberless others of recent as well as of earlier date. It is particularly true of the wife of the naturalist Heller and of the great astronomer, Kepler. It is true of the wife of the illustrious mathematician, the Marquis de l'Hopital. She not only shared her husband's talent for mathematics, but was of special assistance to him in preparing for the press his important _Analyse des Infiniment Petits_. It is true of the wife of Asaph Hall, the illustrious discoverer of the satellites of Mars. Often he was on the point of abandoning the quest of these diminutive moons--which no one had ever seen but which his calculations led him to believe really existed--but he was encouraged by Mrs. Hall to continue his observations, with the result that his labors and vigils were at last rewarded by the startling discovery of Deimos and Phobos. And there is Mme. Pasteur, who, in her way, was quite as important a factor in the scientific career of her immortal husband as were the women just mentioned in the lives of their husbands, to whose triumphs they so materially contributed. One of the great Frenchman's biographers has truly declared that "it is impossible rightly to appreciate Pasteur's life without some understanding of the immense assistance which he received in his home. Whether in discussing forms of crystals, watching over experiments, shielding her husband from all the daily fret of life, or busy at the customary evening task of writing to his dictation, Madame Pasteur was at once his most devoted assistant and incomparable companion. His surroundings at home were entirely subordinated to his scientific life, and his family shared with him both his trials and his triumphs. At the time when Pasteur was engrossed with the study of anthrax, and, after many difficulties and disappointments, had at length succeeded in preparing a vaccine against it, he at once hurried from the laboratory to communicate his great discovery first to his wife and daughter."[248] It was particularly during his long and arduous researches on the disease of silkworms that Pasteur found his wife's aid of incalculable value. For Mme. Pasteur and her daughter then constituted themselves veritable silkworm rearers. They collected mulberry leaves, sorted larvae, and were unremitting in their labors during the continuance of this memorable investigation. And not only in the silk-producing districts of Southern France were they thus occupied, but also in a special laboratory in Ecole Normale, after their return to Paris.