Page:General History of Europe 1921.djvu/793

 Progress of Modern Science and Invention 593 electrical disturbance ; namely, the luminous body. Matter itself may ultimately be proved to be nothing more than electricity. The practical applications of electricity during the past thirty years are the most startling and best known of scientific achieve- ments the telegraph, telephone, electric lights, and electric motors to run cars and various kinds of machines. 1078. Chemistry in Modern Life. The chemist has been able to analyze the most complex substances and discover just what enters into the make-up of a plant or the body of an animal. He has even succeeded in combining ("synthesizing") atoms in the proper proportions so as to reproduce artificially substances which had previously been produced only by plants or in the bodies of animals; among these are alcohol, indigo, madder, and certain perfumes. The chemist is able now to make over two hundred thousand substances, many of which do not occur in nature. He has given us our aniline dyes (made from coal tar) and many use- ful new drugs ; he has been able greatly to improve and facilitate the production of steel. The chemist, since he knows just what a plant needs in its make-up, can, after analyzing a soil, supply those chemicals which are needed to produce a particular crop. He is becoming ever more necessary to the manufacturer, mine owner, and agriculturist, besides standing guard over the public health. II. PROGRESS IN BIOLOGY AND MEDICINE 1079. The Cell Theory and Modern Biology. In the world of plants and animals the discoveries have been quite as astonish- ing as in the realm of matter and electricity. About 1838 two Ger- man naturalists, Schleiden and Schwann, one of whom had been studying plants and the other animals, compared their observa- tions and reached the conclusion that all living things were com- posed of minute bodies, which they named cells. The cells are composed of a gelatinous substance, to which the name of proto- plasm was given in 1846. All life was shown to have its begin- ning in this protoplasm, and the old theory that very simple organisms might be generated spontaneously was shown to be