20 THE NATURE-STUDY OF PLANTS 
We find, then, that as regards the first three factors, 
the two vital functions and their result, there is nothing 
to choose between plants, animals, and human beings ; 
all live under precisely the same laws, enjoying 
health and vigour when they respect them duly, but 
suffering distress, weakness, or death when from one 
cause or another the normal relations between respira- 
tion and nutrition are interfered with or brought 
altogether to a standstill. 
