48 ims BOTANY 
own peculiar characteristics, which, as we shall see later, 
specially adapt the individual to its particular 
environment. 
SuMMARY. 
Oxygen, a gas that supports combustion. It oxidises 
carbon and other substances, and thus sets free energy. 
Carbon is a solid found in all organic substances 
and forms half the dry weight of plants. Organic 
substances therefore char when heated. 
Carbon-dioxide is a heavy gas which arises from 
the oxidation of carbon and is given off at germination. 
It turns lime-water milky. 
Carbohydrates.—_Starch, sugar, cellulose are com- 
posed of carbon, hydrogen, and oxygen. 
Starch gives a blue colour with iodine. It is found 
in most seeds. 
Grape sugar gives a yellow colour when boiled with 
Fehling’s Solution. It is found in most fruits. 
Cellulose, the chief constituent of wood, is pure in 
cotton wool. It gives a blue colour with iodine and 
sulphurie acid. 
Oils are composed of C.O. and H., but not in the 
same proportion as carbohydrates. They are found 
in seeds. 
Proteins are composed of C.0.H.N.S. They are in 
all parts of plants. Protoplasm, the life substance, is 
in the nature of a protein. 
Bean Seed.—Testa, hilum, funicle, micropyle, two 
cotyledons, plumule, hypocotyl, radicle. Starch and 
protein are present. 
Sunflower, a fruit, the seed being in a seed case— 
much oil. 
Castor bean has oily endosperm. <A earunele is 
present. . 
