12 Objects for the Microscope. 



flower, a few bits of stalk, a lily leaf, or small piece of 

 rhubarb stalk, another of cucumber, a thin slice of raw 

 potato, a wallflower, or a primrose any flower : macerate 

 it in water for a day or two, until it begins to decompose, 

 and the smallest portion placed under the microscope with 

 a drop of water will show you the now separating cells of 

 various shape : those in stalks oblong or cylindrical ; those 

 in the surface of petals and leaves square, or round, or 

 hexagonal, or irregular, with zigzag boundaries, or papilli- 

 form, as in the Geranium, Sweetwilliam, &c. ; those of the 

 parenchyma or pulp of the leaf generally oval. In looking 

 at these, you will certainly find a variety of contents which 

 are seldom preserved for any length of time, and which you 

 must therefore observe in the fresh and living plant. 



CELL-CONTENTS. 



In the slice of potato you will find every cell crowded 

 with starch-granules, that is, if it is a good potato ; for starch 

 is to the potato what fat is to an animal, and if it is in 

 " good condition " tne cells should be "full of it. The test 

 of this is a drop of tincture of iodine, which turns the starch- 

 granules to a beautiful blue or violet colour ; and a diseased 

 potato with empty cells will therefore be detected by a drop 

 of that same iodine. 



In the stem of a lily you will find starch-grains, mixed 

 with green granules of chlorophylle, a kind of vegetable 

 wax, which gives the green colour to leaves. 



All our farinaceous plants contain abundance of starch, 

 especially wheat, barley, oats, maize, rice, arrow-root ; and 

 the granules differ from each other in size and form so 

 decidedly, that they cannot well be mistaken by a careful 

 observer. They are prepared for the microscope, and sold 

 as polariscope objects, because the examination of a starch 

 granule with polarized light shows it with a beautiful black 

 cross, revolving with the polarizer ; or, if over a selenite 

 stage, a brilliant play of colours is obtained. 



Besides starch-grains and chlorophylle, you will find 

 something else in the cells of that lily stem, which I select 

 as an easy one to obtain in any garden. In some cells, not 



