. Bacteriology and mycology of foods. Food. 32 BACTERIOLOGICAL APPARATUS only be reliably accomplished by considerable practice and experience. To obtain best position: Use a 16-mm. (f in.) objective; focus upon the object; adjust con- denser until image of window-Bash or flame is in the same plane with object. Practically all substages are provided with means for focusing the condenser: The rays of light should be focused sharply on the object. A little experience will indicate when the proper aperture is. Fig. 27.—Showing Action of Different Parts of the Condenser. (After Bausch.) being used
. Bacteriology and mycology of foods. Food. 32 BACTERIOLOGICAL APPARATUS only be reliably accomplished by considerable practice and experience. To obtain best position: Use a 16-mm. (f in.) objective; focus upon the object; adjust con- denser until image of window-Bash or flame is in the same plane with object. Practically all substages are provided with means for focusing the condenser: The rays of light should be focused sharply on the object. A little experience will indicate when the proper aperture is. Fig. 27.—Showing Action of Different Parts of the Condenser. (After Bausch.) being used. The iris-diaphragm when used with dry lenses should not be more than half open. With the oil inamersion objective, how- ever, the full aperture should be used. Final Hints ''Sometimes the worker may have faithfully carried out all the directions heretofore given and been assured that his lenses possess the above-named quahties as they ought, yet be unable to obtain the desired results. He may be working with a water mount and dry objective become ' immersed' in some water which has worked to the top of the cover glass. His objective may be dirty from a previous ' immer- sion ^ or it may have some other dirt upon the front lens. The field may be covered with specks which revolve when the ocular is turned. The field may be dim or hazy, due to dirt on the back of the objec- tive or a film on the inner surfaces of the lenses of the ocular, or because of moisture settling on the lenses because they have just been brought from a cold into a warm room. He may see great streaks on his field, which are due to his own eyelashes, or he may see small slowly moving bodies floating across the field. With the exception of this last, the ailment has only to be mentioned to suggest the remedy. The musc» volintantes, as these last-named bodies are called, are little specks of. Please note that these images are extracted from scanned page images that may have been digitally enhanced for read
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Keywords: ., bo, bookcentury1900, bookdecade1910, booksubjectfood, bookyear1919
