SELECTION, ETC., OF OBJECTS FOR PHOTOGRAPHING. 109 
a glass slide, and the ripe anthers, held in slender 
forceps, are brought into contact with it; the 
pollen is detached, and falls to the bottom of the 
drop. A little agitation of the slide causes it 
to be distributed in a stratum consisting of a 
single layer of cells. When the alcohol has 
nearly evaporated, a drop of glycerine is put in 
its place, the thin cover is applied, and the super- 
fluous fluid removed with bibulous paper. 
EPIDERMIS OF PLANTS. 
The epidermis may readily be stripped from 
the leaves of many plants, and is well suited for 
photography. Succulent leaves, especially, like 
those of the house-leek, ice-plant, various species 
of lily, century-plant, etc., part with their epi- 
dermis easily, while thin and leathery leaves 
do not. 
The well-defined walls, of cellulose, which 
constitute the outer envelope of vegetable cells 
give good photographic contrast with the cell 
contents, and no staining agents are required for 
its differentiation, as is the case with the cell wall 
of many cells making up animal tissues. 
In the epidermis of plants these vegetable 
cells are arranged in a single plane to constitute 
a membrane, and a variety of mosaic patterns are 
produced as the result of the various forms and 
modes of arrangement of the individual cells. 
In mounting portions of the epidermis for 
photography, the principal difficulty to contend 
with is the presence of air-bubbles, which adhere 
