CHAPTER III 
PLANT MIGRATION 
ALL organisms, animal as well as vegetable, are at 
some period of their existence provided with an 
opportunity of migration. In the animal world, most 
land creatures have legs or wings, which allow them 
to roam about freely—a freedom which is of special 
importance as enabling them to obtain nourishment 
and to avoid disadvantageous conditions. Aquatic 
animals are likewise to a great extent possessed of 
powers of locomotion, but such powers are not so 
essential to them as to terrestrial creatures, since the 
water itself is full of small organisms, both animal 
and vegetable, on which they can feed; hence a large 
variety of water creatures are content to remain 
during much of their lives fixed to one spot, extract- 
ing from the water as it passes by both the supply 
of organic food and the inorganic substances, such 
as oxygen or carbonate of lime, which they require 
for their life processes. These sedentary creatures, 
of which barnacles, sea-anemones, and zoophytes will 
serve as examples, once attached, do not move from 
the spot where they have settled down; but it is im- 
portant to note that not only are their eggs or young 
mostly liberated into the water, and by it transported 
to new homes, but in their juvenile stages they often 
swim vigorously, and thus achieve a wide dispersal. 
48 
