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LABORATORY OUTLINE FOR GENERAL BACTERIOLOGY CONNECTICUT AGRICULTURAL COLLEGE BACTERIOLOGICAL DEPARTMEN SEPTEMBER 1922 LABORATORY OUTLINE FOR GENERAL BACTERIOLOGY PREFACE The esetcises and descriptions in this laboratory manual are intended primarily for students in General Bacteriology. The work outlined can be covered in an eighteen week pzriod having two two hour laboratory periods a weelr, preferably at intervals of two and five days. The course offered at this institution includes to one hour lectures a week. The lectures and laboratory work a1 e planned as far as possible to ,paralel and supplement each A i 3 . ot hei,. Students in this course do not prepare their culture media or sterilize their glassware for we feel that the beginner in bacteriology call use the limited time more advantageously in other directions. The description of bacterial species includes some pathogens Ijut only non pathogenic organisms ai e used in this course. The glossary of bacteriological terms appended will be found helpful to the student beginning the study of bacteriology. The Authors. CONTENTS PART I. The microscope Measurement of bacteria Sterilization Lockers and equipment Examination of unstaiiled bacteria Gelatin Agar Melting and solidifying points of agar and gelatin Air analysis Cautions and directions for identification of unknown cultures Descriptive chart Plate 1. Types of growth in stab and streak cultures Age for examination of various cultures Stains Morphology Descriptions of culture media Descriptions of various species of bacteria PART 11. Water testing Bacteria in milk. Plating method Direct microscopic examination of milk Effect of temperature on keeping quality of milk Bacteria from various sources Distilled water experiment Bacteria in meats Testing for presence of spores Conversion factors Comparison of metric and English systems Glossary of laboratory bacteriological terms Part I. THE BIICROSCOPE The microscope is a delicately adjusted instrument and great care should be exercised in using it to keep it in good condition. The following rules should be observed 1. When not in use keep in the case. Dust causes unusual wear if allowed to work into the mechanism. 2. Alcohol should never be used on the lacquered parts. If oily material is to be removed use xylol with gentle rubbing. 3. Should the stage or objectives become gummed with im mersion oil or balsam it can be removed with lens paper moistened with xylol. 4. Use the plane mirror for daylight and the concave for arti ficial light. 5. Regulate the amount of light by raising or lowering the Abbe condenser. This is done with a screw under left of stage. The higher the condenser the greater the amount of light. Dust in the eyepiece makes the field appear covered with specks. Wipe with lens paper. 6. Do not touch the surface of the lens with the fingers. 7. Objectives of one microscope should not be changed to another even of the same make. 8. To focus with the two highest powered objectives place object to be examined in center of stage. With eyes at the side at the level of the stage lower the objective with the coarse adjust ment until it nearly touches the cover glass. Adjust mirror and condenser to give desired amount of light. Focus slowly upward with the fine adjustment until the object becomes clear. With the 112 or oil immersion objective a drop of cedar oil between the lens and the cover glass is necessary to prevent dispersion of light. 9. c he fine adjustment is used for bringing out details in very small objects consequently has a limited range and is me chanically delicate. When the fine adjustment screw stops do not force it. 10. Never use oil with any but the oil immersion objectives. With Leitz microscopes the 112 objectives oil immersion are copper colored with nickel end. With Bausch Lomb microscopes the oil immersions are nickeled on the lower half. 11...
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