44 FLOURS. 



(29) Pea Flour. 



The pea (Pisum sativum, Linn.) much resembles the lentil 

 in structure, but differs in the shape of the palisade cells, which 

 are square at the apex instead of conical. These are thickened by 

 similar bars visible in surface sections viewed from above, but not 

 when viewed from below (size of the cells, 60//. or more in length, 

 IZ/ui-15/j. in width). The parenchyma of the seed-coat is com- 

 posed of cells similar in shape to those of the lentil, but exhibiting 

 conspicuous intercellular spaces. The cells of the epidermis of 

 the cotyledons are elongated, but in varying directions instead of 

 parallel to one another as in the lentil. The starch grains are 

 rather larger than those of the lentil (30/-C to 47ju), and many of 

 them bear rounded protuberances. The hilum is comparatively 

 seldom fissured, and even then the fissure is not branched as it is 

 in bean starch ; the concentric striae are less regular, and often 

 indistinguishable. 



The diagnostic characters of pea flour are : 



(a) The palisade cells with square ends. 



(b) The characteristic hypodermal cells. 



(c) The epidermal cells of the cotyledons not parallel. 



(d) The starch grains with rounded swellings, less distinct un- 

 branched hilum and less evident strice. 



