38 
PLANTS. 
the flower, as may be readily seen in the pea, whose 
capsule is a pod formed of two tough valves that 
open longitudinally. The pericarpium sometimes 
increases to an amazing comparative size, as in 
the gourd and the melon : it always greatly ex- 
ceeds the size of the seeds, and assumes almost an 
infinite variety of forms. Thus in nuts and stone- 
fruits, the seed is incased in a strong shell, which is 
itself inclosed in a pulp or husk. In grapes and 
many kinds of berries, it is plunged in a glutinous 
syrup, contained within a thin skin ; in apples and 
pears, imbedded in the centre of a firm fleshy sub- 
stance ; and in raspberries and strawberries, scat- 
tered on the surface of a soft pulp. These are only 
a few instances among an amazing variety which 
exists in the different trees, shrubs, flowers, and 
grasses, and which all tend to one great end — dhe 
preservation of the future plant. 
