188 THE HUMAN SIDE OF PLANTS 
course the higher forms of animals can be separated 
easily from the higher forms of plants; but in the 
lower forms, there is no distinction. ‘There are 
many of the lower animals which have no stomach 
or even a trace of a nervous system; while many 
of the lower plants can actually swim through the 
water, taking any course they desire. The most 
skilled scientist cannot be certain whether he is 
dealing with animal or plant. If, then, a dividing 
line cannot be drawn between the lower forms of 
plant and animal life, how can an intelligence be 
assigned to the one in its higher forms without a 
similar power being attributed to the other, espe- 
cially when, with all other powers of the animal, the 
plant favourably compares? 
“There is nothing unscientific,” says Francis 
Darwin, “in classing animals and plants together 
from a psychological standpoint.” 
In a previous chapter it has been shown that 
plants see and are sensitive to the presence or ab- 
sence of light; that they will approach a sunny spot 
from the shade or a shady spot from the sun; that 
an approaching shadow will cause some plants to 
close their petals; thus proving that plants have the 
sense of sight. 
That plants hear has been shown in the instances 
of those sensitive-plants which are susceptible to 
