CHAPTER II. 



cot 



NATURE OF FOOD STORED IN SEEDS AND OTHER 

 PLANT PARTS.* 



17. In the study of the parts of the seed it was found that 

 the seedlings are able to make considerable growth when not 

 supplied with food from the outside. This 

 growth goes on at the expense of food stored 

 in the seed. This food was stored up in the 

 seed during its formation in the ripening of 

 the fruit. In some seeds it is laid down out- 

 side of the embryo and is called endosperm, 

 as in the grain of corn, w r heat, castor bean, 

 etc. In others, while it was first formed as 

 endosperm in the young seed, it was largely 

 or completely absorbed by the embryo during 

 the ripening of the seed, as in the bean, pea, Fi s- * 2 - 



Section through grain of 



squash, sunflower, etc., where it is stored in com. s.c. seed coats; st. 



starch, the aleurone layer 



the Cotyledons Of the embryo. In the Study Hes between the starch and 



seed coats; cot. cotyledon 



of the seeds we have found the general (here the scuteiium)- >. rad- 



icle enclosed root sheath; 



location of the food substance. We wish pi- plumule, 

 now to learn more particularly the form in which it is stored, its 

 nature, as well as the special receptacles and their arrangement. 

 The special receptacles are the cells^ of the endosperm, the coty- 

 ledons, etc., where the food is stored. 



* It will probably be found convenient to study the nature and location 

 of food substances while the student is studying the various seeds, bulbs, 

 shoots, roots, etc., but this short chapter is introduced here in order to 

 avoid the unnecessary description of them with each different object 

 studied. 



f A cell is a unit of microscopic structure in plants. It is like a minute 

 box with cellulose for its walls. Living and growing cells contain the life 

 substance (protoplasm) which has a complicated structure. In some plants 



13 



