2 ORGANISM AND ENVIRONMENT 



regarded as a whole, it is evident that in the case of 

 any given organism they are co-ordinated in such a 

 way that the Hfe of the organism tends to maintain 

 itself as a whole, or at any rate to fulfil its character- 

 istic life-history. This applies not less to the reactions 

 between the organism and its environment than to 

 those between the parts of the organism. In the 

 inorganic world as ordinarily observed and inter- 

 preted we find no such co-ordinated maintenance. 

 How are we to understand its presence in the organic 

 world? This is of course a very old question; but I 

 wish to reconsider it in these lectures in the light, 

 more particularly, of the very rapid advances which 

 have been made during the last few years in the 

 physiology of breathing. 



We are familiar with two opposing theories as to 

 the nature of the co-ordination. One of these is that 

 known as vitalism, which assumes that within the 

 living body there is constantly at work a special influ- 

 ence, the so-called "vital principle," which guides the 

 blind physical and chemical reactions which would 

 otherwise play havoc with the organism. The other 

 is that the body is a very complex and delicate 

 mechanism, so arranged as to bring about the co- 

 ordination. According to one school this mechanism 

 is the result of natural selection, though according 

 to another its origin must be sought in special creation. 

 I hope to be able to convince you that neither the 

 vitalistic nor the mechanistic theory of the relation 

 between organism and environment is tenable, and 



