SEEDS 



291 



The middle layers. The cells forming the middle layers 

 (Fig. 4) have thin, wavy, light-colored walls which are frequently 

 compressed, and it is with much difficulty that their outlines 

 are made out. 



The inner epidermis. The cells forming the inner epidermis 

 are rectangular in form, and they contain reddish-brown cell 

 contents (Plate 123, Fig. 5). 



ENDOSPERM 



The endosperm. The cells forming the endosperm are large, 

 rectangular in outline, usually one layer thick, and they contain 

 aleurone grains. 



EMBRYO 



The embryo. The cells forming the outer layer of the em- 

 bryo are smaller than the inner layers, and they are immediately 

 inward from the layer of endosperm cells (Plate 123, Fig. 7). 



The cells forming the greater part of the embryo are large, 

 rounded, and they contain aleurone grains and fixed oil (Plate 

 123, Fig. 8). 



In white and black mustard are characteristic mucilage and 

 palisade cells. 



In nux vomica, stropanthus, and St. Ignatius's bean are 

 characteristic hairs. 



In physostigma and kola are characteristic starch grains. 



In henbane, capsicum, stramonium, lobelia, and belladonna 

 seeds are characteristic epidermal cells. 



In areca nut, colchicum, saw palmetto, and nux vomica are 

 characteristic thick- walled, reserve cellulose cells. 



In cardamon seed are aggregate starch masses with irregular 

 outlines. 



In bitter and sweet almond, linseed, pepo, and stropanthus 

 are aleurone grains. 



In bitter and sweet almonds are stone cells. 



In linseed, quince seed, and in white and black mustard are 

 epidermal cells with mucilaginous walls and contents, etc. 



