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i 
THE CONDITIONS FOR THE DISTRIBUTION OF PLANTS. 109 
splendid vegetation of many Coral islands may, to a certain extent, 
be attributed to distribution by the sea, though it is a fact that salt 
water will kill most germs of plant life, unless they are protected 
by the above or similar means. Other fruits and seeds—some- 
times whole plants—are occasionally distributed by -fresh water, 
rivers, streams, or floods, but as s whole, this agency cannot be 
considered a very important one. More active is the rain, and in 
colder climates the snow and the ice. The principal action of rain 
in regard to distribution of plants is to bury the seed inthe ground, 
and as a whole to assist inthe germiuation of seeds. Seeds of some 
plants, as many Geraniacee, several grasses, &c., are hygroscopic— 
a quality which by alternative expansions and contractions causes 
a certain movement, probably intended for shifting the seeds from 
one place to another; and according to observations by F. Darwin, 
for burying the seeds in the ground. 
Though animals, birds, and insects but too freq uently damage our 
choicest plants and fruits, their assistance in the distribution of 
plants is very important, and seeds and fruits are frequently a dapted 
to take advantage of this fact. 
The hairy or woolly appendages of seeds and fruits, which I have 
mentioned as adaptations for flight, as also the pubescent and tomeu- 
tose seeds that frequently occur in Malvaceous plants, &c., are 
often of such a nature that they adhere to the skin of animals, 
and ure distributed by these. In other cases seeds and fruits are pro- 
o 
ages, which cause them to stick to the skinsof animals. Such 
vided with hooks, bristles, awns, glands, tuber 
es, or similar append- 
structures are common features in many grasses, Umbellifera, 
Composite, Rubiacew, &c., and are frequently met with in common 
Weeds, as in Achyranthes aspera, Sida carpinifolia, Mimosa pudica, 
Paracaryum, Plumbago zeylanica, &c. More direct is the agency 
of monkeys, flying foxes, and larger birds, which are frequently 
attracted by the colour and fragrance of the succulent fruits, eat 
them and throw the seeds away, often at a considerable distance 
from the place of production. Birds as a whole are still more active 
distributors of plants, at least of those numerous species that have 
a berried, baccate or drupaceous fruit. Such fruits have generally 
a gay colour, are frequently sweet and aromatic, and are altogether 
well suited to tempt the birds. Experience has also established the 
fact that many seeds fail to germinate, unless having passed through 
the birds. Such seeds may, however, succeed when submitted 
15 
