A PLANT THAT MELTS ICE 29 



combining with the oxygen of the air in their 

 bodies. Lungs, in fact, are mere devices for taking 

 in fresh oxygen, which then combines with the 

 food or fuel in the blood of the animal. 



A century ago, Count Rumford pointed out that 

 you might burn your hay as you chose, either 

 in a horse or in a steam-engine ; and that in 

 either case you produced alike heat and motion. 

 What we, call fuel is just carbon and hydrogen. \} I 



/ *> 'I ~ m . / ' / 



separated from oxygeji : and what we call burning V. 

 or combustion is just the, re- union of thq^ oxygen^ 

 with the other elements, accompanied by a giving- / 

 off of heat equivalent in arpount to that originally, n 

 required in order to separate Ihe 1 11 . 



Now, the foodstuffs of most animals are plants 

 or parts of plants, especially seeds or grains, as 

 well as the rich stores of starch or oil laid by in 

 roots, bulbs, and tubers. These are all of them 

 reservoirs of food or fuel, produced by the plant 

 for its own future growth, and meant hereafter to 

 sprout or germinate. All seeds, when they begin 

 to quicken, unite with oxygen and evolve heat ; 

 and this heat is just the same in nature, whether it 

 happen to be set free within or without an animal 

 body. If you give an ox corn, he will oxidise it 

 internally and warm his own body with it ; but if 

 you let it germinate, it will oxidise itself, and so 

 produce a very small but slow fire, which warms 

 both the corn and the space around it. Similarly, 

 all growing shoots combine with oxygen, and, 

 therefore, rise in temperature. In early spring, 

 when the ground just teems with sprouting seeds 



