INTRODUCTION 



II 



the radicle has formed root hairs can plant food be taken 

 from the soil (or other medium in which the seedlings 

 are being grown) ; and not until the plumule has formed 

 green leaves can such plant food be worked over to form 



FIG. 8— GERMINATION IN CLOTH 

 The seeds are laid in rows on the cloth kept damp by sand in the tray below. 



plant tissue. Until then the seedling lives on the food 

 stored in the seed by the parent plant. This food in- 

 cludes starches or sugars, cellulose, fat, proteids or liquids 

 or combinations of two or more of these materials. 



Fully ripened dry seeds are highly resistant to outside 

 influences ; in some cases (squash, pine) continuing vital 



