128 The Study of Animal Life part n 



and increased brightness of the sun ; and since there is no 

 reason why we should not believe in a simple order of 

 consciousness in all simple creatures, that consciousness 

 would certainly become gladness with increased vigour of 

 life, just as it is with ourselves. 



The energy of life, we say, is due to the energy reaching 

 us from the sun ; but how is the radiant energy of the ether 

 used to place the growing shoots on the forest tops, and how 

 is it transformed into the potential energy of wood and 

 other substances ? Our trains move by virtue of the 

 energy stored in the coal ; we burn that in a certain 

 place and get expansive energy of steam, which by 

 mechanical arrangements we convert into the moving 

 energy of the engine ; but where is the boiler, and 

 where the machinery in the plant, by which the energy 

 of the sun's rays is transmuted into life ? The partial 

 answer to this riddle has been found. If we break a 

 newly-grown branch we find the tissues filled with a watery 

 slimy sap. If we open a bud we find the slimy stuff again ; 

 under the bark of trees we find it once more ; it is within 

 the tissues of a bulb, and in growing seed ; indeed, in all 

 those parts of a plant which are capable of independent 

 life we always find what we may call for the moment 

 this slimy sap ; while in the hard inner parts of the tree, 

 which we know can live no more, we find nothing of the 

 kind, — such tissues are quite empty. Life, therefore, we 

 find to have something to do with a certain substance, and 

 this is the first step towards understanding the machinery 

 we have spoken of; we have, as it were, found that the 

 movement of the train is due to the engine, but we do not 

 understand that engine. 



4. Cells, the Elements of Life, — Let us leave the trees 

 now for a little, and turn to the simplest of all living 

 creatures, which live in water and in damp places. They 

 are so small that only a few of the larger ones can be seen 

 as tiny specks moving about in the water in which they 

 live. But they can be seen quite easily with a microscope. 

 We find them to be little transparent drops of living 

 matter. They are not really drops ; many of them have 



