70 NEW ZEALAND NATURE-STUDY BOOK 
undertaken in the field ; but all of it is capable of demonstration 
indoors. Much of it, however, will fail as a medium of education 
if not directed by a teacher possessing both knowledge and skill, 
hence the amount to be attempted will depend largely, if not 
entirely, on the knowledge equipment and tastes of the teacher— 
in short, this particular part of the course should cease where 
dogmatic teaching begins. 
XVII.—_THE DISPERSAL OF SEEDS. 
Plants, unlike animals, are unable to move about ; hence 
a flowering plant is to all intents and purposes confined to 
the spot on which it grows. Its seeds, if not dispersed, 
would fall to the ground close by the parent plant, whose 
shade and presence would greatly interfere with vigorous 
growth. Besides, the soil in the immediate neighbourhood 
of the parent plant might be unsuitable, to say nothing of 
the interference with the proper development of the 
seedlings in consequence of overcrowding. [or these 
and other reasons it is necessary that seeds, so soon as 
they are ripe, be scattered as widely as possible. Hence 
many plants have special arrangements by means of which 
their seeds are conveyed to places suitable for germination. 
Dispersal by the Wind —To secure dispersal by the 
wind many seeds are provided with outgrowths of various 
kinds which, by offering a larger surface to the wind, 
without appreciably adding to their weight, cause them to 
be carried along frequently for a considerable distance before 
falling to the ground. The seed of the Hakea and Sycamore 
is furnished with wings, that of the Thistle and Dandelion 
with a tuft of radiating hairs; whilst the seed of the 
Clematis has a long feathery style. It may be mentioned 
that seeds furnished with wings are invariably found on 
