THE PLANT A LIVING MACHINE. 17 



We now see what the real position of the plant 

 is, to its environment, whether the latter be living 

 or dead. From our point of view, the plant serves 

 as a centre for bringing together the substances 

 obtainable from the soil, and those derived from 

 the atmosphere, and so focussing and directing 

 the radiant energy of the sun upon these sub- 

 stances, that they are broken up, and some of 

 their constituents synthesised, with absorption of 

 energy, into a body, such as starch, containing 

 more energy than did the original substances 

 taken together or separate. It matters little 

 whether the actual carbohydrate thus synthesised 

 is starch, or sugar or inulin : the point is that 

 energy has been gained from outside and bound 

 up with the acquired material for further use. 

 But modern physiology has carried matters much 

 further than this, and especially in the three 

 following directions. 



In the first place, it has shown that much of the 

 energy thus stored from without in the plant is 

 again liberated in the process of oxygen respira- 

 tion, and expended partly as appreciable heat and 

 partly as driving force for stimulating the machinery 

 of the living plant to further activities. 



In the second place, part of it is rearranged 

 with the rearrangement of the molecules with 

 which the energy is bound up, as it were, so that 

 work of various kinds is done in the machinery 

 of the plant : I refer to various metabolic and 

 surface-actions resulting from the peculiar mode 

 of presentment of the resulting substances, for 



B 



