THE GRAIN 



place, these cells become more or less crumpled or bent, often leaving 

 small intercellular spaces where the ends meet (a, Figs. 3, 4, and 5). 



Immediately within the " cross layer " is the inner epidermis of the 

 pericarp. It consists of 

 thinner - walled vermi- 

 form or hypha-like cells, 

 termed " tube-cells " by 

 Vogl, from 1 20 to 250 /z 

 long and 12 to 15 p wide; 

 they lie parallel to the 

 outer epidermal cells 

 running from base to 

 apex, and in a ripe grain 



are either separated from FIG. 3. Transverse section of the pericarp and aleuron 



layer of a ripe grain ( x 210). x, Epidermis ; a, " cross 



g 



layer"; b, "tube-cells" (inner epidermis); d, testa; 

 e, crushed nucellar layer ; g, aleuron layer. 



each other altogether by 

 wide spaces or are joined 

 only at irregular intervals. 



In transverse or longitudinal sections of the ripe grain these " tube- 

 cells " are difficult to observe, since they are isolated and do not form a 

 continuous layer, and the individual cells 

 are crushed into close contact with the 

 testa beneath ; their outlines, however, are 

 easily seen when surface views of strips 

 of the soaked pericarp are examined after 

 the outer epidermis has been removed (b, 

 Figs. 3 and 5). 



FIG. 4. Surface view of the cells (a) of the " cross FIG. 5. a, Cells of the "cross layer " 

 layer " of the pericarp, with thin-walled cells of of the pericarp ( x 210) ; b, tube- 

 trie testa crossing them ( x 210). cells of the pericarp. 



The pericarp in the central region of the furrow is thicker than on 

 the opposite side, and in it are usually developed one or two vacant spaces, 

 where the tissue has been torn asunder during the ripening of the grain. 



