34 ELEMENTS OF AGRICULTURE 



again the crop. There is never a mistake — corn comes 

 from corn seed and wheat from wheat seed with abso- < 

 Jute certainty. 



A seed is the egg from which a plant is hatched. An 

 ordinary seed may well be compared to an egg. It con- 

 sists usually of an outer shell protecting the soft inner 

 portion, which is really the young plant folded up. A 

 sitting hen warms her eggs with the heat of her body 

 till the necessary changes have taken place in the egg, 

 then the chick begins to stir, and soon bursting the shell 

 comes into the world a living animal. The apparently 

 lifeless egg, when warmed by the hen, is changed into 

 a living chicken. The equally dead-looking seed, when 

 warmed in the soil by the sun's heat waves, bursts its 

 shell and becomes a living plant. Most plants drop 

 their seeds late in the fall, when a comparatively small 

 number of heat waves come to the earth from the sun, 

 and the earth is in consequence cool. The seed lies on 

 the surface of the ground all winter, the soft little plant 

 folded up within being protected from the cold and wet 

 by the hard outer shell. In the spring, when the heat 

 waves begin to strike with more and more force on the 

 earth's surface, the plant folded up in the seed begins 

 to feel their effect, and soon bursts its shell and begins 

 its life as a young plant. The warmth of the hen's 

 body seems all that is necessary to hatch the egg, but 

 other things besides heat are necessary to hatch out a 

 seed. Seeds may be kept in a warm, dry place for years, 

 and yet never sprout ; but so soon as they are moistened 

 they will, if alive, begin to sprout and grow. Water, 

 then, as well as heat, is necessary for the sprouting of 



