12 © PLANT LIFE 
complex phenomena of life are at once reduci- 
ble to terms as simple as those which regulate 
the reactions just indicated, and it is beyond 
all doubt that much more refined investigation 
than our present knowledge renders possible 
will be needed ere we shall solve the ultimate 
secrets of life, if indeed we ever are able to do 
so. But we shall go far by employing the 
methods which have already taught us so 
much, methods which consist in exact ex- 
periment and accurate analysis. 
The principal reason why our knowledge 
of the modus operandi of the living organism 
is so largely lacking in precision lies just in 
the vast range of the materials with which 
we are there dealing, and in the consequent 
difficulty of analysing the results of our experi- 
ments sufficiently to be able to refer them 
to their real causes. 
But although it may not be possible as 
yet to explain the great majority of the life 
processes, either of animals or of plants, it 
will soon be apparent that relatively simple 
chemical and physical processes have pro- 
foundly modified the course of evolution of 
structure and form. This is more obvious, 
perhaps, in plants than in animals, because 
the retention of relatively simple mechanisms 
in connection with the absorption of food 
materials has kept the plant free from the 
complications introduced by the development 
of specialised locomotory activity, and the con- 
comitant elaboration of a nervous system. 
