. Botany all the year round; a practical text-book for schools. Botany. i6 THE LEAF the giving off of moisture, just as animals do through the pores of the skin.^ Now, we all know what happens to us if the perspiration glands of our body get stopped up, and hence we need not be surprised if hedgerows can not be 'kept vigorous and healthy by dusty roadsides, nor if even sturdy trees and shrubs take on a sickly look when the summer rain delays too long to give them their accus- tomed bath. 16. Stomata. — The transpiration pores of leaves are called stomata (sing, stoma) from a Greek word meaning
. Botany all the year round; a practical text-book for schools. Botany. i6 THE LEAF the giving off of moisture, just as animals do through the pores of the skin.^ Now, we all know what happens to us if the perspiration glands of our body get stopped up, and hence we need not be surprised if hedgerows can not be 'kept vigorous and healthy by dusty roadsides, nor if even sturdy trees and shrubs take on a sickly look when the summer rain delays too long to give them their accus- tomed bath. 16. Stomata. — The transpiration pores of leaves are called stomata (sing, stoma) from a Greek word meaning "; Generally they are too small to be seen with- out a compound microscope, but their presence can be made manifest by a simple experiment. Place a bit of looking glass against your cheek or your arm on a warm day, and it will soon be covered with a film of moisture from the skin. Next, place the glass in contact with the under side of a healthy growing leaf for thirty to forty-five minutes, and see if you can detect any moisture on it. The deposit will probably be fainter than that from the skin, but the presence of any at all will show that the leaf transpires. There are a few plants, such as the white lily of the gardens {L. caitdidum) and the wandering Jew, in which the stomata are large enough to be seen with ' a hand lens. The common iris also shows them, though not so distinctly. Strip off from the under side of such a leaf a portion of the epidermis, or outer covering. Place it between two bits of glass with the outside uppermost, and. 4. — Portion of the epidermis of the gar- "den balsam, highly magnified, showing the very sinuous walled epidermis cells and three stomata {after Gray). 5 6 S, 6. — Stomata of while lily leaf: 5, closed; 6, open (Gray). ^ Transpiration, though similar in external effects to the perspiration of ani- mals, must not be confounded with it, as the two functions are physiologically quite Please note that
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