Practical dairy bacteriology, prepared for the use of students, dairymen, and all interested in the problems of the relation of milk to public health . est to have,this widely open, for the colored bacteria are more easily seetiwith an open diaphragm. The bacteria are very small, and evenwith this magnifying power it may sometimes be difficult tomake out their shape; but ordinarily their general appearancecan easily be made out. Examine in this way all the culturesisolated in No. 14, and sketch. *No. 16. Comparison of Yeast and Bacteria. Rub up in awatch glass a bit of a cake of yeast with a l
Practical dairy bacteriology, prepared for the use of students, dairymen, and all interested in the problems of the relation of milk to public health . est to have,this widely open, for the colored bacteria are more easily seetiwith an open diaphragm. The bacteria are very small, and evenwith this magnifying power it may sometimes be difficult tomake out their shape; but ordinarily their general appearancecan easily be made out. Examine in this way all the culturesisolated in No. 14, and sketch. *No. 16. Comparison of Yeast and Bacteria. Rub up in awatch glass a bit of a cake of yeast with a little water. Placea drop of the liquid on a slide and examine directly with themicroscope, using a i/6-inch objective. Dry a little of thematerial on a slide and stain exactly as in staining bacteria(No. 15). Study with the immersion lens, comparing the yeast LABORATORY WORK IN DAIRY BACTERIOLOGY 285 cells as to size and shape with bacteria already studied. Huntfor cells showing budding. If these are not found they may beobtained in quantity by planting a little yeast in a weak solutionof molasses in water and allowing to grow for a few hours in. FIG. 81—CENTRIFUGE FOR MILK TESTING(I^te^natia^.^l Instrument Co.) a warm place. Make a sketch of the yeast cells with buds,showing their relative size to that of bacteria. No. 17. Direct Microscopic Study of Milk. For this acentrifuge is needed, having tubes with straight sides, and closedat the bottom with a rubber cork. (Fig. 81.) Place 2 ofthe samples of milk to be tested, after thorough shaking, in thetubes. It is necessary to fill enough tubes with milk from dif- 286 PRACTICAL DAIRY BACTERIOLOGY ferent samples, to balance the centrifugal machine on both in the machine at a rate of 2,000 to 3,000 per minute,for 5 minutes. Remove the tubes from the machine and theywill be found to have a layer of cream at one end, and a smallslimy deposit at the other end next the cork. Holding the tubewith the cream end down, r
Size: 1602px × 1559px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidcu319, booksubjectdairying
