PLANTS AND MEN 
make almost unbelievable changes in floral and 
vegetable form and structure. There has been 
much experimentation of recent years in con- 
nection with the effect of light, both natural 
and artificial, on plant processes. In general, 
it has been established that it is just as injurious 
for a plant to have too much light as too little. 
Steady exposure to light makes for accelerated 
growth of tissue. Lessening light speeds up 
flowering and reproduction. Control over a 
plant’s light supply therefore means that the 
manipulator can produce at will either large, 
luxuriantly foliaged plants which flower late, 
or from the same seed develop small specimens 
blooming exceptionally early. 
Man is not content with merely controlling 
the external conditions which affect vegetation 
but often steps into their internal processes and 
moulds their life-forces at their very fountain- 
head. By the simple methods of selection and 
cross-breeding, he is able to work miracles with 
the laws of heredity, and bridge in a few years 
gaps which a plant would have taken centuries 
to span by ordinary evolutionary processes. 
Luther Burbank is the modern garden 
[219] 
