PLATE IV. 



FIG. 



25. A vertical section of mature barley straw, highly magnified, 



showing the dark woody bundles of spiral and other vessels 

 amongst the elongated fibrous cells. The central portion 

 (pith) is not renewed, the stem therefore becomes hollow. 



26. A portion of silicated epidermis or skin from mature stem, 



showing the curved prickly hairs, highly magnified. 



27. A portion of the epidermis of a leaf without hairs. 



28. A minute portion of a very young awn, with spiral vessels 



(z'), and {Ji) young hairs developing. 



29. A diagram showing the position of the inflorescence relatively 



to the surrounding leaves : a, the oldest leaf; b c, those next 

 formed. 



30. Portion of (e) barley ear, showing the lateral supports {ss) by 



which each grain is protected. 



31. Pollen granules, enormously magnified. 



