CHAPTER II 



THE ORGANISM AS A MECHANISM 



WE propose now to consider the organism purely as a 

 physico-chemical mechanism, but before doing so it 

 may be useful to summarise the results of the discus- 

 sions of the last chapter. Let us, for the moment, 

 cease to regard the organism as a structure a " con- 

 stellation of parts ' -and think of it as the physiologist 

 does : it is a machine ; it is essentially " something 

 happening." What, then, is the object of its activity ? 

 Whatever else the study of natural history shows us, 

 it shows us this, that the immediate object of the 

 activity of the organism is to adapt itself to its sur- 

 roundings. It must master its environment, and 

 subdue, or at least avoid whatever in the latter is 

 inimical. It must avoid accident, disease, and death, 

 it must find food and shelter ; it must seek for those 

 conditions of the environment which are most favour- 

 able to its prolonged existence. Ultimate aims the 

 preservation of its race, ethical ideals do not concern 

 us in the meantime. The main object of the function- 

 ing of the individual organism is that it may dominate 

 its environment, and obtain mastery over inert matter. 

 Consciously or unconsciously it acts towards this end. 

 All those actions which we call reflex, or automatic, 

 or instinctive, have this in common, that the organism 

 in performing them comes into relation with only a very 

 limited region of its environment. But knowing that 



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