ENERGY TEANSFORMATIONS IN LIVING MATTER 129 



forms of energy are developed, by noting as closely as possible 

 the nature of the instrument or transformer and adapting this to 

 its work, and by studying the effect of each form of energy so 

 developed upon various forms of matter, and the routes or trans- 

 formers by which it is dissipated into other forms of energy. 



In all cases we observe that some material agency or arrange- 

 ment is necessary in order that the transference from any one 

 specific form to any other may be effected, and that this agent 

 differs with the forms between which exchange is going on. The 

 machine or structure through which the change is effected may 

 be termed the energy transformer. 



Observation teaches that bodies or substances which by their 

 structure or arrangement are specially adapted for promoting 

 certain energy exchanges are quite inert with regard to other 

 exchanges. 



In the case of some energy transformations the property of 

 acting as transformer appears to be shared by all forms of matter, 

 although in varying degree, while in other transformations the 

 property is most specific, and associated with some special arrange- 

 ment of matter. Thus, for example, all metals possess the pro- 

 perty in varying degree of electrical conductivity, and in inverse 

 proportion act as transformers for the conversion of electrical 

 energy into heat energy. The specific agencies of the green plant, 

 on the other hand, possess in high degree the power of converting 

 light energy into chemical energy, and here act as peculiar energy 

 transformers. Similarly, all enzymes are energy transformers, 

 limited and specialised in range of action, for the transformation 

 of chemical energy. Again, iron in most marked degree (and a 

 few other metals to a less extent) is, by some special structural 

 arrangement, specially adapted to act as a transformer in the case 

 of magnetic energy, effecting its conversion into electrical or 

 mechanical energy, or vice versa. Similarly, for radiant light and 

 heat some bodies are transparent, and transmit these forms of 

 energy unaltered, while others are opaque and transform the 

 energy into other forms. 



It is not necessary to go on multiplying examples, but it may 

 be urged that in exactly similar fashion the protoplasm of the 

 living cell of plant or animal is on account of its peculiar struc- 

 ture and constitution a transformer of energy, specially adapted 

 for the intermediate conversion of chemical energy, presented in 



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