60 Animal Life 
Now let us take a tree with very different 
leaves—the Spanish chestnut (Fig. 9). They 
are long, narrow, and sword-shaped. Why is 
this? The terminal branches of the Spanish 
chestnut are much thicker and stronger than 
those of the beech. Consequently they can 
carry more sail. But the distance between 
the buds is but lhttle greater, consequently 
the leaves cannot with advantage be much 
- wider; but as they must be larger they must 
be long and narrow. Take again the firs and 
pimes. Some have long leaves, in others the 
leaves are short. Why is this? They are, as 
everyone knows, evergreen, but the length of 
life of the leaves differs greatly. Some keep 
them on for little more than a year, others 
two or three years, others eight or ten, the pinsapo nearly twenty. And you will 
find that other things being the same, the longer the life, the shorter the leaf— 
thus securing about the same leaf surface. To look at plants from this point 
of view makes country life, it seems to me, far more interesting. 
Another point in which our conception of plant hfe has 
undergone considerable modification of late years 1s as to 
their power of movement. Those who had not studied the 
question used to consider that animals moved but plants 
were stationary. We now know that many of the lower 
plants, especially in young stages, swim about by means of 
fine hairs known as cilia. In fact, plants move much more 
than is supposed. I have given instances in which they 
actually throw their seeds to considerable distances. Indeed, 
so far from being motionless, 1t would be more correct to say 
that they are in almost perpetual motion, though the changes 
of position are so slow that they do not attract attention. 
I have mentioned a few cases in which the reasons for 
the forms and shapes and colours and habits may be explained 
with more or less probability, but the unsolved problems of 
plant life are almost infinite. To make a collection is no 
doubt interesting, but it is like making a library. What is 
the use of the books if you do not read them? What is the 
value of a collection if you do not use it? The problems of 
plant life are all but infinite. Great indeed as is the pleasure 
which flowers give to the eye, it is less than the delight which 
they afford the mind. They offer an endless series of most 
interesting mechanical, optical, chemical, and other problems. 
It is not going too far to say that there is not a single 
plant—not even the commonest—of which the whole life 
history, properties and structures are fully known to us— 
not one which would not well repay, I do not say the 
attention of an hour, but even the devotion of a lifetime. 
Fig. 8. 
spANis ~CHESTNUT LEAF. 
Fig. 9. 
