Plant Stomata Light Microscope

Plant Stomata in a Light Microscope.

Plant Stomata in a Light Microscope

A slice stripped from the outer coat of the Holly-berry, and is given for the purpose of illustrating the method by which plants are enabled to breathe the atmospheric air on which they depend as much as our- selves, though their respiration is slower. Among the mass of net-like cells may be seen three curious objects, bearing a rather close resemblance to split kidneys. These are the mouths, or "stomata "as they are scien- tifically called, scientific people always liking to use a long Greek word where a short English one would do as well.

In the centre of the mouths may be seen a dark spot, which is the aperture through which the air communi- cates with the passages between the cells in the interior of the structure. In the flowering plants their shape is generally rounded, though they sometimes take a squared form, and they regularly occur at tne meeting of several surface cells. Their edges are protected by certain "pore-cells", or "guard-cells", so called from their function, which, by their change of form, cause the mouth to open or shut, as is best for the plant. In young plants these guard-cells are very little below the surface of the leaf or skin, but in others they are sunk quite beneath the layer of cells, forming the outer coat of the tissue. There are other cases, where they are slightly elevated above the surface.

Stomata are found chiefly in the green portions of plants, and are most plentiful on the under side of leaves. It is, however, worthy of notice, that when an aquatic leaf floats on the water, the mouths are only to be found on the upper surface. These curious and interesting objects are to be seen in many structures where we should hardly think of looking for them, for they may be found existing on the delicate skin which envelops the kernel of the common walnut. As might be expected, their dimensions vary with the character of the leaf on which they exist, being large upon the soft and pulpy leaves, and smaller upon those of a hard and leathery consistence. The reader will find ample amusement, and will gain great practical know- ledge of the subject, by taking a plant, say a tuft of Groundsel, and stripping off portions of the external skin or "epidermis" from, the leaf or stem, &c., so as to note the different sizes and shapes of the stomata.

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