FORM AND STRUCTURE 



11 



roundish, elongated oval, lying 

 close to the endosperm. The 

 plumule and radicle arise in 

 its shallow exterior. On the 

 inside of the scutellum occurs 

 a so-called epithelium of pali- 

 sade-formed cylindrical cells, 

 with delicate walls. Its pur- 

 pose, apparently, is to absorb 

 the amylaceous material of 

 the endosperm. Opposite the 

 scutellum and in front of the 

 embryo is a small scale-like 

 appendage, the epiblast, pres- 

 ent only in wheat and oats 

 and apparently of no func- 

 tional importance (Fig. 9). 



10. Reserve food-materials. 

 In the seeds of cereals, the 

 reserve food is stored within 

 the endosperm, while in those 

 of legumes, it is stored in the 

 seed leaves or cotyledons. 

 There are two main groups of 

 reserve materials, the non- 

 nitrogenous, including carbo- 

 hydrates, fats, and oils ; and the 

 nitrogenous, composed of va- 

 rious proteins, and commonly 

 referred to under the general 

 term of aleurone. The em- 

 bryo itself contains oils, pro- 

 teins, and carbohydrates. The 



FIG. 5. A part of the section 

 in Fig. 4, taken at cd, further 

 enlarged : a, starch endo- 

 sperm ; 6, aleurone layer ; cdef, 

 investing membranes, repre- 

 senting the original integu- 

 ments of the ovule and the wall 

 of the ovary ; g, starch grains ; 

 h, aleurone grains. (X 108.) 



