BARK. 
135 
It is to the cuticle of wheat, oats, rye, and some of the grasses, 
that we are indebted for straw and imitation of Leghorn hats. 
In their manufacture, the straws are scraped, so as to have noth- 
ing left but the cuticle. It has been ascertained that the outer bark 
of many of the grasses contains silex, or flint ; in the scouring 
rush, ( Equisetum,) the quantity of silex is such that housekeep- 
ers find it an excellent substitue for sand in scouring wood or 
metals. A singular property of the cuticle is, that it does not 
seem to be subject to the same changes as the other parts of 
bodies ; it is of all substances found upon animal or vegetable 
matter, the least indestructible. The cuticle is sometimes like 
the skin of animals, clothed with wool or down, and it then be- 
comes an important security against the effects of heat and cold. 
The leaf of the mullein has its cuticle covered with a kind of 
wool ; the pericarp of the peach has a downy cuticle. 
2d. Cellular Integument , is situated beneath the epidermis or 
outer skin of the bark. This substance you will recol- 
lect is composed of minute cells filled with a resinous sub- 
stance, which is usually green in young plants. This cel- 
lular layer possesses glands, which when submitted to the 
action of the light carry on the process of decomposing car- 
bonic acid gas, by retaining the carbon and evolving the 
oxygen gas. The cellular integument envelopes branches 
as well as trunks of trees and herbaceous stems ; it ex- 
tends into roots, but there it neither retains its green colour 
nor decomposes carbonic acid gas. It is the seat of colour, 
and in this respect analogous to the cutis, or true skin of 
animals, which is the substance situated under the cuticle, 
and is black in the Negro, red in the Indian, and pale in 
the American. In the leaves of vegetables, the cellular in- 
tegument occupies the spaces comprised between the nerves, 
and is of a green colour ; in flowers and fruits it is of vari- 
ous colours. The cellular substance of some aquatic plants 
is filled with air ; in the pine, sumach, &c. it is filled with 
the proper jufees of the plant. This herbaceous envelope 
of the trunks of trees, after a time dries, appearing on the sur- 
face in the form of the cuticle, and often cleaves off. It is 
renewed internally from the cambium. 
The petals of flowers are almost entirely composed of cellular 
texture, the cells of which are filled with juices fitted to refract 
and reflect the rays of light, so as to produce the brilliant 
and delicate tints which constitute so great a portion of their 
beauty. The fuci, a species of sea weed, and some other plants 
appear to be altogether composed of cellular texture. 
Cellular integument — How situated — Its use — How renewed — 
