!*" 



Journal of Applied Microscopy. 495 



cut when slightly softened. Paraffin is perhaps the best material for the pur- 

 pose, as it holds the grain so firmly that it may be cut in any direction. No 

 elaborate microtome is necessary, any simple section-cutting contrivance answers 

 quite well. Great care must be exercised, however, to have a knife with an 

 extremely thin and sharp edge. The upper surface of the knife must be wet 

 with alcohol, and the sections are best removed with a camel's hair pencil, and 

 if it is desired to keep them for any length of time, they may be placed in a 

 shallow dish of alcohol, to which is fitted a ground-glass cover. 



The requisite degree of thickness, or rather of thinness, is a matter of some 

 importance, for if too thin the starch grains fall out in cutting, and the gluten 

 cells are disagreeably opaque if too thick. But as a great number of sections may 

 be readily cut, a selection of such as are entire, and of a sufficient degree of 

 transparency may be made with a hand lens. 



The sections cannot be mounted ^-^-iS^^^S^sSj-.,- 

 in balsam, as that renders the starch " ^** " ' ' •-?->-- 

 grains so transparent that they are 

 quite obliterated under the microscope, 

 but glycerine jelly is a very satisfactory 

 medium, and is soon made ready by M 

 placing the containing bottle in a cup V'^- 

 of hot water. i-*^ ' 



-His.— -jz. 



Having slides and cover-glasses m J^|i..;.:-3 



readiness, take a section on a camel's 

 hair pencil and place it upon a slide, 

 the center of which has been marked 

 on the back bv a dot of ink. ij€l- "^7"' 



If the slide is held inclined, a little ;; ^'' 



water, placed with the brush above . ,, 



the section, will run down and carry "-j<^^u ,, 



with it nearly all the surrounding -^' 



grains of starch, but if any remain Transverse Section of a Grain of Wheat. 

 ^1 1 ,., 1 -^1 ^1 Variety, Buda Pesth, X 20. 



they may be readily removed with the ,_Fruit coats; epidermis, mesocarp, and endo- 

 brush. carp. 2 — Seed coats. 3 — Gluten cells, 



. f , , 1 . ,, ,. or perisperm. 4 — Starch cells, 



After absorbing all surrounding ^ ^^ endosperm. 



water, place a drop of glycerine jelly 



upon the section, take a cover-glass in the forceps, moisten one side with the 



breath, and placing its center over the section, lower it carefully upon the gelatin, 



and if this is sufficiently fluid, the cover will settle to its place without using any 



pressure. 



Any attempt to move the cover, or to press it down after it is in place, will 

 cause a cloud of starch to issue from the cells. 



Should the gelatin become so hard that the cover-glass does not settle 

 down of its own weight, warm the slide gently over the lamp. 



When the section is mounted and placed under the microscope, we have the 

 appearance presented in the drawing, which represents a grain of wheat ampli- 

 fied about forty diameters. 



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