206 



SUGAR BEET SEED. 



These are essential for protoplasm development, of 

 which the plant cells are made up. 



The seed leaves, as shown in Fig. 6i) penetrate 

 the surface soil doubled, and have a natural tendency, 

 in consequence thereof, to rotate with some force, — to 

 assume an upright position. This seems to be assisted 

 by the inclined position of the ascending root. The 

 seed leaves then have not yet opened. This takes place 

 in two ways: Either directly, as shown in Fig. 65, or as 

 in Fig. 66, where they are at first convex, and assume 

 their natural position after some days. 



Interesting experiments to determine the most 

 desirable depth at which to plant beet seed have 



FIG. 64. 



Fig. 66. 



resulted in some practical facts; among these we may 

 mention, that seeds were planted to a depth of three 

 inches, and uncovered after 200 days. As soon as 

 exposed to the air they gave evidence of full vigor. In 

 most cases, however, when the soil was damp, germi- 

 nation took place at this depth ; but these germs being 

 unable to come to the surface, died, never having gone 

 beyond the first stage of their existence. 



It is evident that if the seed be at too great a depth 

 it cannot reach the upper surface. After an interval 

 of time, if the resistance to the ascending shoot is over- 



