Source of content: Botanical test guide
Operation method
Experiments in the use of light microscopes, plant plotting methods and micrometers
Principle
1. to understand the basic structure and imaging principles of light microscope, basic knowledge of drawing and types of micrometer and its construction. 2. to understand the use and maintenance of light microscope. 3. to understand the use and maintenance of light microscope. 4. to understand the use and maintenance of light microscope. Botanical drawing method, use of micrometer.
Materials and Instruments
Permanent mounts Slide specimens Plants Move I. Optical microscope Caveat 1. When measuring, the same object to be measured more than five times and use its average value to reduce the error. Common Problems I. Homework and synthesis questions 1. using knowledge of drawing, draw the structure of a light microscope and label the parts. For more product details, please visit Aladdin Scientific website.
Xylene. Distilled water.
microscope dissecting mirror micrometer plotter microprobe paper gauze scale ruler scale ruler straightedge magnifying ruler nine-gauge magnifying glass zoom-in mirror plotter plotter plotter pen plotter paper
1. Structure of the optical microscope
The basic structure is divided into two parts: the optical system and the mechanical device. 
(1) Optical system of the microscope
Eyepieces, mounted on the upper end of the barrel, also known as catch eyepieces, commonly used eyepieces are 8X, 10x, 15X, than X.
Objective lens: mounted on the lower end of the barrel of the rotator, also known as the receiver lens, the general microscope has 3-4 objective lenses, 10X below the low confidence objective lens, 40X-65X objective lens for high confidence objective lens, more than 90x is the oil lens.
Light collector: installed in the mirror stage below the light transmission hole, mainly by the focusing lens and variable diaphragm (also called iridescent diaphragm), can be adjusted up and down and zoom in and out, in order to adjust the appropriate luminosity.
Reflector: there are two sides, one is a plane mirror, the other is a concave mirror, can be freely mobilized in both horizontal and vertical directions to align the light source.
(2) Mechanical devices of microscope
Mirror base: at the bottom of the microscope, used to support the whole microscope.
Mirror column, mirror arm and tilting joint: a short iron column perpendicular to the mirror seat, called the mirror column. The curved part on the mirror column is the mirror arm. Where the mirror arm joins the barrel, there is a tilt joint that allows the barrel to be tilted for observation.
The load table (mirror table): for the placement of slides, there are two kinds of round or square. There is a round hole in the center, and there is a slide clamp on each side of the back of the hole to fix the slide from moving.
Mirror tube: a cylinder made of metal, with an eyepiece at the upper end and an objective lens at the lower end, the inner wall of the tube is sprayed with black non-glossy paint in order to avoid diffusion of light.
Objective converter: disk-shaped, fixed in the lower end of the barrel, there are 3-4 objective lens screw port, objective lens according to the magnification of the order of high and low.
Adjuster: located at the back of the lens barrel on both sides, there are two pairs of gears, a pair of large called coarse adjuster, when rotating, can make the lens barrel up and down to lift, rotate a circle can be raised and lowered by 10 mm. a pair of small fine adjuster, rotate a circle only to make the lens barrel to lift 0.1 mm.
2. The imaging principle of optical microscope
Optical microscope is the use of optical imaging principle to observe the structure of the plant body. The imaging principle of the microscope is shown in the figure. 
3. Use of the optical microscope
(1) Microscopy environment
The room should generally be wide and clean, with a solid foundation without vibration, little moisture and dust, and no corrosive reagents should be placed. When natural light is used as a light source, direct sunlight should not be used to avoid damage to the eyes of the observer. Generally use the scattered light from the sun, especially the reflected light from the sky or white clouds.
(2) Placement of the microscope
Place the microscope on the tabletop of the laboratory bench, about 5 cm from the edge of the bench, slightly to the left of the operator, the right side of the drawing paper and other experimental tools.
(3) Lighting
Turn the focusing knob to lift the lens barrel, and then turn the objective converter, so that the low-magnification objective lens is facing the aperture, when you hear a slight resistance to the sound of the card, the objective lens has been aligned with the aperture. Adjust the reflector, the iridescent aperture of the light collector, etc., so that the light in the field of view is uniform and bright.
(4) Device slide specimen
Take a slide specimen (such as onion root tip longitudinal permanent preparation) placed on the carrier table, with the specimen pusher clamped slide specimen, adjust the specimen pusher so that the specimen is located in the center of the through-hole.
(5) Use of low magnification lens
Rotate the low magnification objective lens to the center and carefully turn the coarse adjuster downward to about 1 cm from the slide. After that, then use the coarse adjuster to lower the low magnification lens to about 2-3 mm from the slide, through the eyepiece to view the specimen, while in the counterclockwise direction with the coarse adjuster to make the lens barrel slowly rise, slowly move the slide, until the object image is seen. At this point, the fine adjuster is further turned up and down to make the object image as clear as possible.
(6) Use of the high magnification lens
First find the material under low magnification as in the above procedure, then move the part to be observed under high magnification to the center of the field of view and press it tightly with a spring clip without further movement. Replace the high magnification lens and turn it up and down with the fine adjuster until a clear image appears.
(7) Use of oil mirror
①First find the object to be observed with the low magnification lens, then change to the high magnification lens, place the object in the center of the field of view, and maximize the amount of light collected by the light collector.
② Turn the lens barrel upward and add a small drop of cedar oil to the light collector and coverslip.
③ Lower the lens slowly so that the oil lens is immersed in the drop of oil and close to the object to be observed, then use the fine adjuster while observing, adjusting it from the bottom upwards to find the object to be observed.
④ After the observation, rotate the lens away from the slide and wipe off the cedar oil on the lens with mirror paper.
Second, the requirements and methods of drawing
Drawing one of the most important laboratory report, more vivid and specific than the written record, can help find them to understand the structure and characteristics of the nucleus, is the study of plant morphology and anatomy must be mastered when the skills and techniques. In thesis and scientific research reports, it is also often necessary to draw some morphological diagrams, outline drawings or cell structure diagrams to represent the morphology and structure of cells, tissues and organs. Botanical drawing is different from art drawing, its specific requirements are as follows:
1. First of all, attention should be paid to scientific and accuracy. The object to be drawn (specimen or section, etc.) must be carefully observed, the relevant written records, experimental instructions, etc. must be studied, the characteristics of the various departments must be correctly understood, and the normal typical materials must be selected, so as to ensure the accuracy of the morphology and structure and to illustrate a certain scientific problem in the drawing.
2. Before drawing, according to the number and content of the drawings required by the experimental instructions, the position and proportion of the drawings should be arranged on the drawings, and a place should be left for writing the titles and notes. 3.
3. first sketch, that is, with a sharpened HB pencil gently sketched out the outline of the figure on the drawings, so as to facilitate modification. Sketching should pay attention to the outline of the drawing against the observation of the size of the outline is consistent with the real thing. 4.
4. Sketch by modification and then draw the object. Formal drawing should be used 2H a 3H drawing hard pencil, according to the direction of the hand stroke, traced with the object to match the line. Lines should be outlined in one stroke, uniform thickness, smooth and clear, no bifurcation at the joints and traces (do not repeat the depiction). 5.
5. plant drawings - the general use of dots against the shade, indicating light and dark and color before the shade, to give a sense of three-dimensional. Points should be round and neat, uniform size, according to the need to flexibly grasp the changes in sparseness, can not be used to smear the method of shading instead of dots.
6. drawings should be kept neat and tidy, notes are written in block letters, should be as detailed as possible, and require parallel lines lead, preferably on the right side of the figure, must be neat and consistent.
7. Drawings and notes should always be written in pencil, not fountain pen, colored water pen or ball point pen.
8. The title of the experiment should be written on the top of the report paper, and the title of the figure and the name and part of the plant material used should be written on the bottom of the figure with magnification.
The use of micrometer
1. Types of micrometer and its structure
(1) Mirror micrometer
The microscope micrometer is a special slide, in the center of it has a graduated scale, the whole length of 1 mm, divided into 10 large cells, each large cell is divided into 10 small cells, a total of 100 small cells, each small cell length of 0.01 mm, that is, 10 um. Some of the whole length of 2 mm, divided into a total of 200 small cells, the length of each cell is still 10 urn. in the periphery of the ruler there is a small black ring, it is easy to locate the position of the ruler. (2) eyepiece micrometer.
(2) Eyepiece micrometer
Is placed in the eyepiece a ruler.
There are two types of fixed and mobile.
The fixed type is a round glass piece, 20-21 mm in diameter, on which various forms of scales are engraved, both linear and reticular.
The linear type can be used to measure the length of an object, usually 5 mm long, divided into 5 large compartments, each of which is subdivided into 10 small compartments, for a total of 50 small compartments.
Net type is mainly used to count the number and measure the area of the object, which is marked with a square grid on the mesh scale. The size and number of squares varies from 25, 36 and 49, to 100 squares in a large square and 25 smaller squares in a central square.
Mobile is mounted in a special eyepiece, the right side of a small wheel that can be converted to control the wheel has a scale, divided into 100 grids, this wheel every turn, the eyepiece can be moved within the indicator line from one end of the scale to the other end of the movement of a grid.
2. the use of micrometer
(1) length measurement method
① Put the microscope micrometer on the carrier stage, adjust the microscope, observe the scale of the microscope micrometer and move it to the center of the field of view.
② Screw down the eyepiece cover, and place the eyepiece micrometer with the graduated side down on the diaphragm of the field of view in the eyepiece.
③Adjust the stage micrometer and the eyepiece micrometer so that their scales overlap, and calculate how many umo each small grid of the eyepiece micrometer corresponds to. The grid value of the eyepiece micrometer (Um): (number of grids of the stage micrometer X 10)/number of grids of the eyepiece micrometer.
④ Remove the stage micrometer and replace it with a slide specimen, then use the eyepiece micrometer to measure the size of the object, the actual length of the object is equal to the number of frames of the eyepiece micrometer corresponding to the object multiplied by the obtained grid value. If you use a different magnification of the objective lens and eyepiece, must be recalculated, the same method as before.
The use of mobile eyepiece micrometer, the length of each grid on the scale is similar to the above calculation method. The use of the original eyepiece on the microscope should be withdrawn, the mobile eyepiece micrometer inserted, then, on the one hand, observe the field of view, one hand twist the knob, so that the field of view can move the vertical indicator line and the end of the object being examined aligned to write down the number of degrees that it represents. Then make the indicator line moved to the other end of the object being examined aligned, and then write down the number of degrees it indicates, the difference between the two, is the length of the object being measured. The length measured with this micrometer is more accurate than the fixed type.
(2) Quantitative calculation method
Usually with an eyepiece mesh micrometer. Before counting, should first be compared with the mirror micrometer, calculate the area of each small square. Then calculate the number of objects in each small square. In order to avoid counting the same object twice, where the object falls on the thin line on the four sides of the square grid, each grid is only counted down and to the right, and the rest of the direction belongs to its grid.
2. draw the roots, stems, leaves, flowers, fruits and seeds of a typical green flowering plant.
3. observe a permanent preparation of a longitudinal section of an onion root tip using a light microscope and plot what is observed.
4. Observe several slide specimens using a microscope and measure the dimensions of what was observed using a micrometer.