352 VEGETABLE PHYSIOLOGY 
CHAPTER XXII 
THE PROPERTIES OF VEGETABLE PROTOPLASM 
The influence of the environment upon the structure of 
plants we have seen to be far-reaching. Different con- 
ditions of the surroundings are followed by differences of 
structure, which are greater in proportion as the time 
during which those conditions act is more and more pro- 
longed. The living substance of the plant is clearly the part 
influenced by the environment, for we have seen that the 
skeleton and other non-living parts of the plant owe 
their construction to its activity. We may therefore with 
advantage pause at this point to examine a little more 
closely the properties which are exhibited by vegetable 
protoplasm. 
We have seen throughout all the foregoing chapters 
that all the processes which conduce to the well-being of 
the plant are, to a large extent, if not entirely, under the 
control of the living substance. Though the absorption 
of the raw materials of its food from the air and the soil is 
due to physical processes, these are nevertheless largely 
regulated by the behaviour of the protoplasin under all sorts 
of varying conditions. The manufacture of food from these 
crude materials, and its subsequent distribution, the accumu- 
lation and dissipation of energy, the processes of nutrition 
and growth, are all subject to the same regulation. 
But there are also other properties of protoplasm which 
have not so far been more than incidentally referred to. 
The plant exhibits particularly the power of appreciating 
