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 III. Methods of Breeding ; Sterilization ; Liquid Culture Media ; Preparation of Beef-bouillon ; Potato Cultures ; Beef-bouillon Gelatin and Agar-agar; Uses of Food Media for Obtaining and Maintaining Pure Cultures ; Plate Cultures ; Petri Dish Cultures ; Esmarch-s Roll-tube Cultures ; Pure Cultures ; Culture of Anaerobic Bacteria; Incubators ; Thermo-regulators and Safety Burners. METHODS OF BREEDING. Were the microscopical examination of the hacteria as they occur in their natural state the only means at our disposal for studying them, our knowledge of bacteriology would never get beyond certain very narrow limits. "We might know something of the wide-spread existence of these micro-organisms, we might observe their frequent presence in connection with certain forms of disease, and we might perhaps even be able in some cases to prove the regular presence of the same species (as judged by form and appearance), and then, by jumping at a conclusion, maintain it to be the source of the pathological conditions in question. But this would be all, and even this little would stand on weak feet. It is always unsatisfactory to form a judgment from the mere appearance of the smallest living organisms, whose forms are the simplest imaginable, and experience has shown to what great errors one may be led by so doing. Bacteria, which seemed to agree fully as to appearance, turned out on more careful examination to be altogether different species, which had nothing in common but their similarity of form. The disadvantage of this way of proceeding was soon recognized, and attempts were therefore made to render the bacteria as independent of their natural conditions as possible, in particular to sever the parasitic kinds from the organisms whose parasites they are, to bring th...