66 Scientific Proceedings, Royal Duhlm Society. 



retardation and dissipation like the rest of nature. That such 

 conditions are not incompatible with the definition of the dynamic 

 attitude of the organism, but only involve a coefficient of thermo- 

 dynamic efficiency less than unity, can be shown by analogy 

 with our inanimate machines which, by aid of hypotheses in 

 keeping with the second law of thermo-dynamics, may be sup- 

 posed to fulfil the energy-functions of the plant or animal, and, 

 in fact, in all apparent respects conform to the definition of the 

 organism. 



We may assume this accomplished by a contrivance of the 

 nature of a steam-engine, driven by solar energy. It has a boiler, 

 which we may suppose, fed by the action of the engine. It has 

 piston, cranks, and other movable parts, all subject to resistance 

 from friction, &c. Now there is no reason why this engine should 

 not expend its surplus energy in shaping, fitting, and starting into 

 action other engines. In fact, in reproductive sacrifice, all these 

 other engines represent a multiplied absorption of energy as the 

 effects of the energy received by the parent engine, and may in 

 turn be supposed to reproduce themselves. Further, we may 

 suppose the parent engine to be small and capable of developing 

 very little power, but the whole series as increasing in power at 

 each generation. Thus the primary energy relations of the 

 vegetable organism are represented in these engines, and no viola- 

 tion of the second law of thermo-dynamics involved. 



We might extend the analogy, and assuming these engines to 

 spend a portion of their surplus energy in doing work against 

 chemical forces — as, for example, by decomposing water through 

 the intervention of a dynamo — suppose them to lay up in this 

 way a store of potential energy capable of heating the boilers of a 

 second order of engines, representing the graminivorous animal. 

 It is obvious without proceeding to a tertiary or carnivorous 

 order, that the condition of energy in the animal world may be 

 supposed fulfilled in these successive series of engines, and no 

 violation of the principles governing the actions going on in our 

 machines assumed. Organisms evolving on similar principles 

 would experience loss at every transfer. Thus only a portion of the 

 radiant energy absorbed by the leaf would be expended in actual 

 work, chemical and gravitational, &c. It is very certain that this 

 is, in fact, what takes place. 



