This is obvious in the structure of the teeth and talons of the
tiger; and in that of the legs and claws of the parasite which clings
to the hair on the tiger's body. But in the beautifully plumed seed of
the dandelion, and in the flattened and fringed legs of the
water-beetle, the relation seems at first confined to the elements of
air and water. Yet the advantage of plumed seeds no doubt stands in
the closest relation to the land being already thickly clothed by
other plants; so that the seeds may be widely distributed and fall on
unoccupied ground. In the water-beetle, the structure of its legs, so
well adapted for diving, allows it to compete with other aquatic
insects, to hunt for its own prey, and to escape serving as prey to
other animals.
The store of nutriment laid up within the seeds of many plants seems
at first sight to have no sort of relation to other plants. But from
the strong growth of young plants produced from such seeds (as peas
and beans), when sown in the midst of long grass, I suspect that the
chief use of the nutriment in the seed is to favour the growth of the
young seedling, whilst struggling with other plants growing vigorously
all around.
Look at a plant in the midst of its range, why does it not double or
quadruple its numbers? We know that it can perfectly well withstand a
little more heat or cold, dampness or dryness, for elsewhere it ranges
into slightly hotter or colder, damper or drier districts.
Pages:
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109