The microscope; an introduction to microscopic methods and to histology . be demonstrated by coating a fine glass rod (§ 144) withone or more coats of collodion or celloidin and allowing it to dry, andthen mounting in 50% glycerin as above. Employ a 3 mm.(^ in.) orhigher objective, light with transmitted light, and it will be seen thatwhere the glycerin touches the collodion coating there is a dark line—next this is a light band, and finally there is a second dark line wherethe collodion is in contact with theglass rod.* (Fig. 93). Fig. 93. Solid glass rod coated with col-\lodion to show a dou
The microscope; an introduction to microscopic methods and to histology . be demonstrated by coating a fine glass rod (§ 144) withone or more coats of collodion or celloidin and allowing it to dry, andthen mounting in 50% glycerin as above. Employ a 3 mm.(^ in.) orhigher objective, light with transmitted light, and it will be seen thatwhere the glycerin touches the collodion coating there is a dark line—next this is a light band, and finally there is a second dark line wherethe collodion is in contact with theglass rod.* (Fig. 93). Fig. 93. Solid glass rod coated with col-\lodion to show a double contour. Towardone end the collodion had gathered in a fusi-form *Some of the rods have air bubbles in them, and then there results a capillarytube when they are drawn out. It is well to draw out a glass tube into a finethread and examine it as described. The central cavity makes the experimentmuch more complex. 98 INTERPRETATION OF APPEARANCES [CH. Ill § 147. Optical Section.—This is the appearance obtained inexamining transparent or nearly transparent objects with a microscopewhen some plane below the upper surface of the object is in upper part of the object which is out of focus obscures the imagebut slightl}*. By changing the position of the objective or object, adifferent plane will be in focus and a different optical section most satisfactory optical sections are obtained with high objectiveshaving large aperture. Nearly all the transparent objects studied may be viewed in opticalsection. A striking example will be found in studying mammalianred blood-corpuscles on edge. The experiments with the solid glassrods (Fig
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
