PLANTS IN GENERAL 575 
presumably the first things to manifest individualized powers 
of choice upon our planet; and plants have so chosen that 
animals have been born and enabled to realize the highest 
opportunities of life. Hence, because some plants have 
chosen as they did, we are now able to choose as we do. 
One of the earliest results of plant choice was doubtless 
the fixed mode of life; and with this we may connect the 
building of a protective cellulose covering and framework 
readily permeable by fluid raw-food materials. The firmness 
of this framework, combined with its power of conducting 
fluids, permitted eventually the building, even upon land, 
of enormous structures hundreds of feet in height. Fixity, 
together with their powers of absorption, have thus enabled’ 
plants to attain in some cases the longest life and the greatest 
size of any organisms. Preferring to be home-keepers rather 
than hunters their more tranquil lives have given neither 
opportunity nor occasion for such specializations of sensitive- 
ness as are involved in the rapid and highly complex re- 
sponses of animals. Hence it is that their modes of life 
appear so different from ours although but modified mani- 
festations of the same fundamental, vital power. 
It is just because of the contrasts between vegetable and 
human life that plants are able to serve our needs in so many 
ways. They feed us because they have retained the power 
of food-making which our line of life has lost. They shelter 
us because they have learned how to form in wood a con- 
structive material better than any we or our ancestors could 
ever make. They clothe us because the cellulose fibers of 
their bodies make a better covering than the hairs our bodies 
have retained. They warm us and work for us because they 
can store up sunshine, as we cannot. They help to make us 
well partly because their waste-products are so different 
from ours. They excite our admiration by doing to perfec- 
tion so many things we cannot do at all. They harm us only 
when we have not learned to know them and to behave 
toward them as we should. There are thus abundant reasons 
why mankind should study the economic properties of plants 
as fully as possible. We may be sure there will always be 
much to learn regarding the relations of plants to human 
