BOTANY. 30 
atmosphere by means of the leaves. Thus the plant decomposes carbonic 
acid, assimilates the carbon, and liberates the oxygen; an animal, on the 
other hand, deprives the air of its oxygen, and liberates carbonic acid. 
OXYGEN is next in importance to carbon. It is usually found in combination 
with hydrogen, forming water. NirroGen is less an universal constituent 
than the other, being chiefly found in the younger parts and the seeds. 
These four elements occur as binary compounds in water and oily matters : 
as ternary in starch, gum, sugar, and cellulose; and as quaternary in gluten, 
eqaseie, albumen, and fibrine. The latter compounds have for their base a 
substance known as proteine (C‘°, H*', N*, O'*), with the addition of certain 
proportions of sulphur and phosphorus. 
The principal inorganic constituents of plants are formed of combinations of 
chlorine, iodine, bromine, sulphur, phosphorus, potassium, sodium, calcium. 
magnesium, aluminum, silicon, iron, manganese, and copper. 
Sitica abounds in grasses, giving firmness to the stem. It is sometimes 
found aggregated in the joints of the bamboo as tabasheer. Lime is found in 
all plants, in some existing in large quantity. It occurs as a carbonate on the 
surface of some plants. Sopa and Porasu are also of constant occurrence. 
Plants growing near the sea exhibit a preponderance of soda, while those that 
are Inland abound most in potash. Iron and Maneaness are found in small 
quantity ; Copper has been detected in coffee. 
B. Propucts AND SECRETIONS OF PLANTS. 
Having thus very briefly mentioned the principal elements found in 
plants, we proceed next to a summary of their most important compounds. 
The first to be mentioned is sTarcuH, which is stored up to serve as nourish- 
ment either to the developed plant or to the embryo. Its chemical 
composition is C!?, H'®, O'". Starch may be deposited in seeds, roots, stems, 
receptacles, &c. Sometimes starch is associated with poisonous or acrid 
juices. Jnuline is a substance analogous to starch, and found in Elecampane 
and other plants; lichenine, another variety, is found in Cetraria islandica. 
or Iceland moss. The action of sulphuric acid, or of malt, on starch, or long 
boiling in water, results in the production of a soluble substance, called 
dextrine, and is one of the stages through which starch passes to become 
sugar. 
Gum (C'?, H'', O'') is another substance found abundantly in the vegetable 
kingdom, and is one of the forms through which organic matter passes during 
the growth of plants. There are two forms of gum: one soluble in water (ara- 
bine or mucilage), the other only swelling up into a gelatinous mass (bassorine. 
cerasine, and pectine). Arabine is known familiarly as gum arabic ; combined 
with cerasine it is found in the gum of the cherry and plum tree. Mucilage 
is present in many plants, as in the mallows and in linseed. Bassorine forms 
the chief part of gum tragacanth. Pectine is obtained from pulpy fruits, as 
the apple and pear. It forms a jelly with water, and when dried resembles 
isinglass or gelatine. 
39 
