12 ANNUAL 



locomotion, and are appropriated to totally diflferent uses. This, however, so 

 far from being derogatory to our own species, is looked upon as a mark of 

 superiority. Why, then, may we not, in the same manner, look upon the 

 differentiation of office in the different members of the solar system as a 

 mark of superiority, instead of an evidence of inferiority ? Here, as I 

 have said, we have the sun in a state rendering it utterly unfit, as far as we 

 know, for habitation by living beings, but still performing most important 

 functions in relation to the whole of the solar system. This brings me to 

 another philosophical doctrine which has come very much forward of late 

 years, and which is known by the name of the conservation of energy. It 

 would take too long a time, and lead me too much out of the way, to give any 

 precise definition of what we mean by this ; but I will endeavour briefly 

 to give a general notion. Let us take the case of a steam-engine. The 

 steam-engine may be said to do work, but that work is done at the expense 

 of something ; there is a loss of something : the coals under the boiler are 

 consumed, and were it not for that coiTsumption we could get no work out 

 of our engine. But what are the coals which have to be consumed in order 

 to produce the requisite result ? They are the relics of extinct vegetation. 

 Whence comes the energy resident in the coals, together with the oxygen of 

 the air ? If the two are bnrnt, we get carbonic acid, and can do nothing 

 further in the way of combustion. It all comes, originally, in the shape of 

 radiation from the sun. Under the influence of solar radiation, under 

 the influence of light, plants are able to decompose, by a process which we 

 do not understand, the carbonic acid of the air, thus appropriating the car- 

 bon, and at the same time setting the oxygen free. This is exactly the 

 reverse of the process which takes place under the boiler of a steam-engine, 

 where the carbon is combined with oxygen, and the combination produces 

 the heat by means of which the engine is worked. Were it not for light, 

 plants could not grow — I mean plants in general ; the fungi are, so to 

 speak, vegetables of prey ; and, just as animals are all of them dependent for 

 their life upon plants, so are the fungi. I say all animals are dependent 

 upon plants for their life, for, although lions and tigers do not eat plants, 

 they eat the animals which do. If there were no plants, you would not have 

 those animals, and if you did not have those animals the lions and tigers 

 would starve, so that in one way and another the radiant energy coming 

 from the sun is, so to speak, essential to the carrying on of life on this earth 

 as we know it, and it may be, by analogy, of life in the other planets of the 

 solar system. This differentiation of function, of which I have spoken, is 

 no derogation to the construction of the system, but rather the reverse. So 

 much for the conservation of energy. I would refer, in conclusion, to 

 another philosophical doctrine which has been brought into notice of late 

 years, and which is called the dissipation of energy. According to the 

 principle of the conservation of energy, there is no loss of energy from the 

 sun, but the heat radiated from that orb is gradually converted into energy 

 which travels through space in the shape of radiation, and a portion of 



