12 THE BOOK OF NATURE STUDY 



The seeds already mentioned may be classified in the following 

 groups : 



I. SEEDS WITH Two COTYLEDONS. Epigeal Cotyledons. 

 Radish, Mustard and Cress, Dwarf French Bean, Pumpkin and 

 Gourd, Buckwheat, Horse Chestnut, Beech, Holly, Gorse. 



Hypogeal Cotyledons. Pea, Broad Bean, Kidney Bean, Oak. 



II. SEEDS WITH ONE COTYLEDON. Wheat, Barley, Maize, 

 and those of all Grasses. 



Or they may be grouped, according to the presence of food 

 in the embryo or outside the embryo. 



Albuminous Seeds. Buckwheat, Maize, Barley, Wheat, 

 Oats. 



Exalbuminous Seeds. Radish, Mustard and Cress, Beech, Holly, 

 Gorse, Horse Chestnut, Pumpkin, Pea and Bean, Oak. 



GROWTH OF THE RADICLE. Attention has been drawn to 

 the growth of the cotyledons and plumule before that of the 

 radicle, because the growth of a radicle takes place out of sight, 

 and in order to observe it seeds must be grown in moist air, or 

 on a sponge or blotting paper, in sawdust or in sand. All 

 these give good results, provided the seeds have sufficient 

 moisture, heat, and air. Mustard and cress grow very readily 

 on a piece of sponge, suspended in a glass bottle with water at 

 the bottom so as to keep the air moist. The mouth of the bottle 

 may be covered with a thin strip of cork, leaving an opening on 

 each side, in order that the air may have easy access to the 

 seeds. The following is a diary kept of the growth of mustard 

 seeds on a damp sponge : 



1907. 



March 5. Seeds sprinkled on damp sponge. 

 6-8. Seeds are swelling. 

 9. The first root (the radicle) bursts its way through 



the seed-coat. 



,, 10. Root-hairs appear behind the tip of the root. 

 12. The seed-leaves come out and turn green. 



