PLANTS. o7 



growth of ])lants, and even to the si)routhig of seeds. 

 Soil is always more or less porous near its surface, and 

 it is lilled with air, which suj)})lios the sprouting' seed 

 with oxygen. 



Depth of Planting. — Most seeds would sprout and grow 

 if dropped upon the surface of the soil in a rainy season, 

 when the atmosphere is damp enough to supply the 

 needed moisture, hut it is generally safer and hotter to 

 cover them with soil. 



The ])roper depth of planting will depend ujion the 

 nature of the soil, climate, croj), etc. In very wet or 

 cold seasons, it is hotter to cover the seed but little, so 

 that it may have hotter access to the air and the warmth 

 of the sun. In warm, dry seasons, it should 1)0 buried 

 more deo]»ly, so as to secure sufficient moisture. 



In some sections of the country, and in some special 

 seasons. ludian coi-n will thrive best when ])lanted at a 

 depth of several inches, while ordinarily a light covering 

 is better. 



JNIany kinds of seeds will not grow at all if buried 

 deeply. The seeds of weeds remain dormant in the soil, 

 nntil they are brought near the surface by plowing or 

 harrowing, where sufficient air and heat are supplied, 

 and then they spring up and grow vigorously. 



Seeds are snpposed to contain a supply of nourishment 

 sufficient to support the young plant until the ascending 

 stem can reach the opon air. 



In some cases of deep ])lanting, Avhile there may be 

 oxygen enough to produce growth, the supply of food in 

 the seed becomes exhausted before the surface is reached, 

 and the ])lant perishes. 



Germination. — The ])rocess of germination, or sprout- 

 ing of seeds, includes three points. 



