42 FLOURS. 



(28) Lentil Flour. 



The lentil (Lens esculenta, Moench) resembles most leguminous 

 seeds in structure. 



The seed-coat is composed of the three following layers : 



(1) An epidermis consisting of a layer of palisade cells (about 

 40//, by IO/A) with a lumen that gradually tapers towards the 

 cuticle ; towards the upper part the wall is thickened by nearly 

 vertical bars, the sections of which are distinctly seen in the sur- 

 face view. The outer end of the cell is not flat but shortly and 

 bluntly conical. 



(2) A layer of parenchymatous cells (about 15//. by 15/*) ; these 

 are contracted in the middle, and hence assume the shape of an 

 hour-glass ; they differ from the hypodermal layer of the bean in 

 not containing calcium oxalate crystals. 



(3) A layer of irregular parenchymatous cells with thin walls ; 

 this layer varies very much in the extent to which it is developed 



The cotyledons are covered with an epidermis consisting of 

 polygonal cells, all of which are elongated in the same direction. 

 The cells of the cotyledons themselves are polygonal, their walls 

 are thin and occasionally exhibit small pits. They are filled with 

 starch and aleurone grains. The former occupy a position that is 

 intermediate between bean and pea starch as regards their shape 

 and appearance. Many are ovoid but less regularly so than bean 

 starch ; many exhibit a fissured hilum and distinct concentric 

 strise, but in others the hilum is not to be seen nor are the striae 

 distinct ; size of the larger grains, 30^ to 40/*. 



The diagnostic characteristics of lentil flour are : 



(a) The palisade cells with conical ends. 



(b) The hour-glass cells u ithout calcium oxalate. 



(c) The nearly parallel epidermal cells of the cotyledons. 



(d) The. thin-walled cells of the cotyledons. 



(e) The starch intermediate in character between pea starch and 

 bean starch. 



