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increased circumference of the circle, the supply of food is considerably 
increased. Not only should the main roots be spread horizontally, but 
the lateral fibres should be so arranged as to cover as great a surface as 
possible. 
We have now to consider the reproductive organs—the flower and 
fruit. The floral envelopes, the calyx and corolla, are not always present 
in the same flower. The calyx is the outside whorl of leaves ; some¬ 
times it consists of a number of leaves more or less united together. 
The calyx when green, with the small, leaf-like appendages called bracts, 
perform similar functions to those of leaves ; they decompose carbonic 
acid, and give off oxygen under the influence of light. The corolla, 
which is situated between the calyx and stamens, does not throw off 
oxygen. 
The bodies immediately within the corolla are the stamens, or male 
organs, which produce a dust-like powder, usually yellow, and called 
pollen. In the centre of the flower is the pistil, sometimes more than 
one, seated immediately on the miniature seed-vessel. When the flower 
i3 perfect, or attained its full growth, a viscid fluid exudes from the 
summit or stigma of the pistil. About this time the outer cases open, 
and set free their pollen. When grains of pollen fall on the viscid 
stigma, tubes are said to pass down the style, when present, into the 
ovary, and are supposed to come in contact with the ovules, which by 
some means, apparently not well understood, are fertilized. 
A knowledge of the effects of seed-bearing on plants has a practical 
value, and should be clearly understood. The organized matter which 
is expended in the formation of leaves, is returned again to the plant 
many times over when they reach maturity. ‘The first effect of the 
production of leaves is weakness—the final effect of their production is 
strength.’ Flowers and fruit, on the contrary, require to be fed by 
leaves throughout their entire growth ;. they are formed at the expense 
of all other parts of a plant; they check or diminish, instead of adding 
to, the growth or development of plants, as leaves do. Annual plants 
are so exhausted when they perfect,their seeds that they die, but persist 
in nipping off the flowers ; and these plants may be made to live two or 
more years. In this way the tree mignonette is obtained. The sap, 
which otherwise would have been expended in flowers and seed, accu- 
i 
