Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER II. B ACTERIOLOGY. The increase in the knowledge concerning the lowest forms of life, and the discovery within recent years that these often have a truly causative action in the excitation of many maladies, have greatly facilitated the study of the causes and prevention of disease. In fact, it is largely to this advance in knowledge and to the confirmation of the germ theory that much of the success of modern hygiene and sanitation is due. The unicellular, vegetal micro-organisms divide themselves into two general classes with respect to their manner of reproduction, viz., those that multiply by budding—the blastomycetes, and those that increase by simple division or fission—the schizomycdes. In the former class we have the hyphomycetes or mould-fungi, and the saccharomycetes or yeasts, examples of these being familiar to every one. However, it is with the fission-fungi or bacteria, as they are now more generally known, that we are most concerned as sanitarians, since they practically include almost all those vegetal micro-organisms that are more or less closely connected with the production of disease, comparatively few of the yeasts and moulds being pathogenic, and then only indirectly or in a minor degree. Bacteriology, then, is the science of those unicellular, vegetal micro-organisms that multiply by direct division (fission), or, as occasionally happens, by the development of spores. Its study consists in the examination by meansof the microscope of the form and method of growth of these minute plants, in their artificial cultivation on or in suitable media, and in the determination of the effects of the inoculation of pure cultures upon animals. To this may be added another field of research that gives promise of rapid development in the near future, viz...