CHAPTER IV. 



ACTION OF THE NERVOUS SYSTEM INTERMEDIATE 

 BETWEEN THE FORCES OF THE ENVIRONMENT AND 

 THE ULTIMATE EFFECTS IN THE ORGANISM. UNI- 

 VERSALITY OF NERVOUS ACTIVITY, OR THE NER- 

 VOUS PROPERTY, IN LIVING MATTER. 



We have seen in the previous chapter! that the 

 life and development of an organism are \sustained 

 and moulded by the forces acting upon the OTganism 

 from the environment. When these forces are 

 altered the growth and development are altered or 

 life may cease. The manner of the transmutation 

 of the force in the environment to the force dis- 

 played by the organism is very obscure. We can 

 assert, however, that the forces of the environment 

 must very readily affect that instable chemical 

 and molecular condition which we have seen to 

 be a characteristic of living matter. This alteration 

 in the chemical and molecular constitution must 

 produce the effects which we see as movements of 

 the mass and changes of its shape. 



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