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 M. Pasteur employed in 1857, and which enables him to obtain microscopic organisms in a state of purity—the only means of arriving at certain results. An infinitely small drop of the blood from a case of malignant pustule is taken, and it is sown in the cultivating fluid constituted by a froth of beer-yeast; a little drop of this fluid is taken again, and sown in a new medium of the same kind, and so on. Thus the media of culture may be multiplied indefinitely to a certain extent during years by the aid of a single droplet of blood taken originally from the case, and one may have always a liquid the inoculation of which in certain animals, such as the sheep or Guinea-pig, reproduces in those animals malignant pustulæ. If this fluid is filtered through a plaster filter, nothing results from the inoculation of the fluid parts which have traversed the filter, but, if the figurate elements which remain on the filter be inoculated, all conditions of the pustular disease are produced. It is the same with the cholera of fowls, and perhaps with puerperal septicæmia."

Marey on Electrical Fishes.—Of a communication from Professor Marey to the Paris Academy of Sciences on electrical fishes, a brief summary is given in the "Revue Scientifique," from which we learn that the author employed a telephone in studying the nature of the electrical discharge of the gymnotus, and the torpedo. Physiologists long ago pointed out certain analogies of innervation, chemical composition, and structure observable between muscles and the electrical apparatus of these animals. It remained to be discovered whether these analogies also exist in the functionment of the two organs. Marey's experiments go to show that the electrical and the muscular functions are in reality homologous, and that they are destined to explain each other. The author also investigated the question whether in those species of fishes which give the electrical discharge there is to be observed a multiplicity of electrical discharges just as a multiplicity of shocks are to be observed in muscular action. The experiments yielded affirmative results. They were made according to the graphic method, as also with the aid of the telephone, the latter instrument being specially adapted for this kind of investigation, inasmuch as it gives a sound when it is traversed by successive currents of sufficient frequency.

Variable Stars.—In directing attention to a certain remarkable star, the "Academy" relates an interesting passage of history connected with it. A Jesuit Professor at Ingolstadt, Christopher Scheiner, was one of the first observers of sun-spots, having noticed them in March, 1611. In accordance with the rule of his order, he communicated his discovery to Budæus, his superior, who, being a disciple of Aristotle, would not accept the observation as correct, inasmuch as no such thing was to be found mentioned in the works of "the Philosopher." When Scheiner had satisfied himself that he had made a true observation, he was permitted to publish the fact, but anonymously. Accordingly, he addressed several letters to Welser, a wealthy Augsburg patrician, and a great patron of learned men; these were printed, and copies sent to Galilei and other astronomers. In the autumn of 1612 Welser published three more letters by Scheiner, under the title "De Maculis solaribus," etc., the second of which, dated April 14, 1612, records observations of Jupiter and his satellites from March 29th to April 8th, among them some observations to which Professor Winnecke, of Strasburg, has lately drawn attention. In order to understand why observations of the satellites of Jupiter were mixed up with those of sun-spots, one must bear in mind that at that time Scheiner still assumed the spots to be merely satellites of the sun, and thus avoided inconvenient questions respecting the purity of the sun's light, which the Aristotelians would not give up. While observing Jupiter's satellites he saw something which offered, as he fancied, a new analogy in support of his opinion; for on March 30, 1612, he remarked in the field of the telescope, besides the four satellites, a fifth star, which he had not noted the previous night. This star decreased in, brightness from night to night, and had, on April 9th, already passed the limit of visibility. Scheiner, moreover, thought he had remarked a small amount of motion, and he