86 THE PHILOSOPHY OF BIOLOGY 



compare it with all that has been spoken and written 

 since 1869, even with the utterances of the British 

 Association of the year 1912, and he will find that it 

 expresses the point of view of mechanistic biology far 

 better than all the subsequent restatements. The 

 only difference he will find is that the latter have 

 become (as William James has said about academic 

 philosophies), rather shop-soiled. They have been 

 reached down and shown so often to the enquiring 

 public, that each display has taken away something 

 of their freshness. 



Now Huxley's example leads up so well to the 

 consideration of the differences between the chemical 



activities of the organ- 

 ism and those of in- 

 organic matter that we 

 may consider it in some 

 FIG. s. detail. What, then, is 



the difference between 



the explosion of a mixture of oxygen and hydrogen, 

 and the photo-synthesis of starch by the green plant ? 

 In the case of the synthesis of water we have an 

 example of an exothermic chemical reaction. We are 

 to think of the mixture of oxygen and hydrogen as 

 existing in a condition of ' false equilibrium." It 

 may be compared with a weight resting on an inclined 

 plane. 



Suppose that the plane is a sheet of smoothly 

 polished glass, and that the weight is a smooth block of 

 glass. By canting the plane more and more an angle will 

 be found at which the slightest push starts the weight 

 sliding down. Now in the case of the explosive mixture 

 of oxygen and hydrogen we have a chemical analogue. 

 Either the gases do not combine at all at the ordinary 

 temperature or they combine ' infinitely slowly." 



