21 



more or less oval in shape, which is very distinct. The column 

 cells are roughly hexagonal in shape, with thickened cell walls, 



Figure 12 

 Fig. 12. Bean. (1) Palisade cells with "light" line; Subepidermal cells 

 with calcium oxalate crystals; (2) Palisade cells in cross section; (3) Starch 

 grains. 



but no intercellular cavities. This layer of cells is only one 

 cell thick. Each cell contains one large monoclinic crystal of 

 calcium oxalate; very rarely more than one crystal is present, 

 and never more than two at the most. Fig. (12) shows the ele- 

 ments mentioned in connection with the common bean. 



CAROB BEAN. 



{Ceratonia Seliqua, L.) 



Grotmd carob beans are used as a cattle food to some ex- 

 tent, and while in general the seeds resemble those of other legumes, 

 there are a few characters which make the identification of the 

 grotind product a comparatively simple matter. In the cells of 

 the mesocarp are found large, brown, wrinkled bodies, which are 

 characteristic ; on treating with dilute alkali and heating carefully 

 a deep blue or violet color is obtained. The long palisade cells 



