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merit. Heat, light, and moisture are the other con- 

 ditions under which vegetable life exists, as they 

 rouse to action the slumbering vital power in the 

 seed, and develop the plant from it, if the situation 

 is such that the young plant can obtain its inorga- 

 nic food from the soil and its organic food from the 

 atmosphere. 



The seed contains within itself all the organic 

 constituents of plants in the form of starch, 

 albumen, and fat, as well as the inorganic elements ; 

 and is thus enabled to supply from its own resources 

 any element which nature may find necessary for 

 the further development of the plant. 



When the seed is brought under the influence of 

 heat, air, and moisture, some curious changes take 

 place in its component parts ; it absorbs moisture, 

 begins to swell, and from that time absorbs oxygen 

 rapidly, which, affecting first the nitrogenous 

 compounds, changes completely the nature of the 

 compounds present in the seed, converts the starch 

 into cellulose, and, by depositing it in the shape of 

 cells, produces a root downwards into the soil, and 

 a shoot developing subsequently into one or two 

 leaves upwards into the air, which parts have 

 thenceforth to absorb from without the nourishment 

 necessary for the further development of the plant. 



If seed is allowed to germinate in water instead 

 of in the soil, the plant will continue growing, 

 although it receives no portion of its inorganic food 



