Bacteria

a cla of very minute microscopic organisms or microbes which are regarded as of vegetable nature, and as being the cause of accompaniment of various diseases, as well as of putrefaction, fermentation, and certain other phenomena. Some of the better known of these organisms are so exceedingly minute, that under the highest power of improved microscopes they appear no larger than the periods of ordinary type. Various cla ifications have been proposed for them, for they differ largely in size, form, and mode of multiplication.