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. 



