150 THE NEW PHYSIOLOGY. 



is thus completely justified on the ground that biological 

 observations cannot be expressed or described in terms 

 of ordinary physical working hypotheses. For a more 

 detailed discussion of this position in the light of the 

 empirical facts of physiology I may perhaps refer to my 

 recent book, Organism and Environment. 



I must now pass to the question whether biological 

 and psychological categories must also be treated as 

 different. To this question it seems to me that there are 

 still clearer reasons for returning an affirmative answer. 



When we examine the organic wholeness and per- 

 sistency which shows itself in the life of an organism 

 we see at once that life is limited on all sides by what 

 we can only interpret as physical and chemical condi- 

 tions. If the oxygen percentage in the air breathed 

 falls low enough, or the external temperature rises or 

 falls sufficiently, life no longer dominates the phenomena. 

 In every direction we see similar limitations. 



A plant may be regarded as the type of what appears 

 to be a mere organism. It is very sensitive to changes 

 in its environment, and is helpless against numerous 

 accidental changes, though human foresight can often 

 quite easily guard it. A conscious organism is distin- 

 guished by the manner in which it overcomes these 

 hindrances. It is aware of, and avoids, neutralises, or 

 even takes advantage of them. It adapts its behaviour 

 in such a manner as to maintain itself in the presence 

 of what is outside the mere organic unity of its life. 

 But in so doing the organism shows itself to be more 

 than a mere organism : it includes within the unity of 

 its life what seemed to be independent. In other words, 

 the biological interpretation of the phenomena of 



