Measuring the size of bacteria

1. The micrometer of the micrometer is composed of an eyepiece micrometer and a mirror micrometer. The eyepiece micrometer is a circular glass piece with a precise aliquot, divided into 5mm on a 5mm ruler. Share (Figure 14 - lC). The actual length of each eyepiece of the eyepiece micrometer varies with the magnification of the eyepiece and the objective lens, so it must be calibrated with the micrometer before the use.
The micrometer of the stage is a dedicated slide with a precise bisector in the center (Fig. 14-1A). Generally, a line with a length of 1 mm is divided into 100 small cells, each of which is 0.01 mm long or 10 μm long. The eyepiece measures the length of each micrometer.

2. Calibration of the eyepiece micrometer The inner lens of the eyepiece is unscrewed, and the eyepiece micrometer is gently placed on the partition of the eyepiece with the scaled side facing down. Place the stage micrometer on the stage of the microscope with the graduated side facing up. First observe with a low power microscope, adjust the focus distance, after seeing the scale of the micrometer of the clearing table, turn the eyepiece so that the scale of the eyepiece micrometer is parallel with the scale of the micrometer of the stage, and the line on the left of the two feet coincides. Find another line that coincides with two feet to the right (Fig. 15-L).

3. Calculation method calibration formula: eyepiece micrometer length per division (μm) = number of grids of two micrographs between the two coincidence lines × 10 格 two grid lines between the two coincidence lines of the eyepiece micrometers, for example, eyepiece micrometer 20 The small grid is equal to the micrometer of the mirror micrometer. The known micrometer is 10μm per grid, and the length of the 3 grid is 3×10=30μm, so the length of each grid is correspondingly on the eyepiece micrometer. 3 × 10 ÷ 20 = 1.5 μm. The above calculation method is used to respectively correct the actual length of each micrometer of the micrometer under the low power microscope, high power microscope and oil mirror.

4. Determination of the size of the cells The micrometers of the microscope were removed and replaced with E. coli and S. aureus slide specimens. The target was found under low magnification and high magnification, and then the micrometer was measured under the oil microscope. The size of the cells was measured. First measure the length and width of the bacteria to occupy the number of grids of the eyepiece micrometer, and then calculate the length and width of the cells by the length of each grid of the micrometer. And detailed in Table 15-1.
For example, the eyepiece micrometer is 1.5 μm per cell under this microscope. If the average length of the cell is equivalent to 2 cells of the eyepiece micrometer, the cell length should be 3×1.5μm= 3.0 μm.
Generally, the size of the cells is measured, and 10 to 20 cells should be measured, and the average value can be determined to represent the size of the bacteria.