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828 been almost universally recognized. The processes by which he has arrived at his discoveries and the success which has attended his application of them are best told in his own language, and are thus told in his address before the recent International Medical Congress, which is published in the present number of "The Popular Science Monthly." This address, the "Westminster Review" says, "was as fascinating in the unerring sequency of experiments as in the unbounded prospects of preventive medicine foreshadowed, and the masterly unraveling of some of Nature's most occult secrets."

M. Pasteur in 1880 proposed the application of the method which he used in seeking the cause of the silk-worm disease, to the detection of a parasite destructive to the phylloxera, and its cultivation as an antidote to that pest of the grape-vine. He said in a "programme for researches," which he communicated to the Academy of Sciences, on this subject, suggesting an inversion of the problem studied in the case of the silk-worm: "Let us seek a parasite for the phylloxera species, and, far from combating it, let us cause it to multiply and fasten upon the phylloxera till it destroys it, as the pébrine parasitic corpuscle so easily destroyed the silk-worms. . . . The rapid multiplication of the phylloxera is only a trifle beside the vital and propagative power of certain parasites. . . . The hall of the Academy of Sciences is very large; it has a capacity of hundreds of cubic metres. I am sure I could fill it with a liquid of such a nature that, on planting in it a parasitic microscopic organism of the fowl, the whole immense mass would, in the course of a few hours, be troubled by the presence of the organism in such abundance that all the phylloxeras in the world would be, in number, only as a drop of water to the sea compared with the numbers of the parasite of which I speak."

Notwithstanding this, he is so confident of the efficiency of the methods of treatment which his researches indicate, that he has been able to say, in his work on the silk-worm disease, that "it is in the power of man to make parasitic maladies disappear from the surface of the globe, if, as is my conviction, the doctrine of spontaneous generations is a chimera."

Another field of investigation, in which M. Pasteur has made a few preliminary steps, is that of the transmission of human diseases by microscopic organisms. He has now numerous co-laborers in these fields, in England, France, Germany, and other nations, many of whom have become famous through their researches, and who are extending the range of investigation every day; but he was the first to direct attention to this branch, and is still the leader of the company.

M. H. Bouley, speaking in the name of the Academy of Sciences, before the annual meeting of the "Five Academies," said, in special reference to M. Pasteur's work: "See how, at once, Nature has suffered one of her most impenetrable secrets to be snatched from her—the mystery of contagions is unveiled; and Science, enlightened by the