DISEASE, Oran TIlLony or. The theory that several enthetic diseases are caused by entrance into the body of germs of a vegetable nature, which during their growth produce chemical changes and give rise to chemical prod ucts. These chemical products, like other poi sons, alter functions. disturb the pnwesses of nutrition and repair. and cause disease. The germ theory, in a less accurate form, was pro posed by a few investigators as early as the seventeenth century. (See BACTERIA.) Van Lecuwenhoek's diseovery and description of the inicro-orl.rdnisnis which his imperfect -trinnew, brought into view interested Lange and Ilauptinann. who theorized at once an fhe important ride the miscalled 'animalcules' might play in the production of disease. Aiming the maladies which they considered to be probably due to conlayium animalum were epilepsy. gout, pleu risy. typhus fever, measles, smallpox, and puerperal fever. In 1701 Andry and announeed that syphilis has a similar origin. Lancisi, in 1718, made a parallel claim for malaria. Following these most valuable deduc tions and theories eame the publication, in 1762, of the results of the investigations and deduc tions of .1ntonius Plenciz, a Viennese physician, who declared that all infections diseases were caused by micro-organisms, and that the infective material consisted of either minute living ani mals or plants. letting a flood of light upon the whole subject through these brilliant discoveries of the truth. Ile stated his belief that differenees in the length of the period of lnenhat ion of dis• eases were due to differences in the time of development of special germs, as they multiplied in I he body. 1 le suggested the eouveya nee of germs
through t he air. 1 le made original invest igat ions into the nature of the pnwesses of pntrefnetion and fermentation, and stated as a conclusion reached hy his imp:, that such processes re stilt from the presence, growth, and multiplica tion of living organisms. Following the publica tion and discussion of these statements arose the theory of spontaneous generation of minute animal and vegetable organisms, advocated by iecdhaut in 1749. after loosely conducted ex periments. Bonnet. in 1762. Lazarus and Spal lanzani in 1769, Schultze in 18:36, Schwalm in 1S37. Helmholtz in 1S-13. Schroeder and Von Dusch in 1534, Hoffmann in IS60, Chevreul and Pasteur in 1861, all contributed results of ac curate scientific experiments which showed the absolute falsity of the theory of spontaneous generation. I tut, incredible as it may now seem, it was not till 1S76 that the combined results, philosophical. chemical, and biological. of Tyn dall and Cohn set the question at rest and estab lished the fact that "all life conies from life," to use the words of Harvey's law. About 1573 the germ theory of disease was authoritatively restated, and germ causation became an accepted principle.