132 The Life of the Spider 



them. Now physiology teaches us that not a 

 fibre works without some expenditure of energy. 

 The animal, which can be likened, in no small 

 measure, to our industrial machines, demands, 

 on the one hand, the renovation of its organism, 

 which wears out with movement, and, on the 

 other, the maintenance of the heat transformed 

 into action. We can compare it with the 

 locomotive-engine. As the iron horse performs 

 its work, it gradually wears out its pistons, 

 its rods, its wheels, its boiler-tubes, all of which 

 have to be made good from time to time. The 

 founder and the smith repair it, supply it, so 

 to speak, with * plastic food,' the food that 

 becomes embodied with the whole and forms 

 part of it. But, though it have just come from 

 the engine-shop, it is still inert. To acquire 

 the power of movement, it must receive from 

 the stoker a supply of * energy-producing food ; ' 

 in other words, he lights a few shovelfuls of coal 

 in its inside. This heat will produce mechanical 

 work. 



Even so with the beast. As nothing is 

 made from nothing, the ^^'g supplies first the 

 materials of the new-born animal ; then the 



