CARBOHYDRATES 



IS7 



Those from potato tubers are flattened irregularly oval grains 

 of comparatively large size, with an excentric nucleus (i, Fig. 79). 



Large and small grains are present in the endosperm-cells of 

 wheat, barley and rye ; they are all flattened and lentil-shaped 

 with a central nucleus (2, Fig. 79). 



In the cotyledons of the seeds of, pea, bean and other legu- 

 minous plants, the grains are oval and kidney-shaped as in 4, 

 Fig. 79, with radiating cracks or fissures in the centre. 



In oats the grains are oval and compound (3, Fig. 79), the 

 component fragments («) being small and angular. 



Fig. 79. — (i) Starch-grains of potato : n nucleus of a grain. (2) 

 Starch-grains of wheat. (3) Slarch-grains of oat ; a a compound 

 grain ; n fragments of a compound grain. (4) Starch-grains of hean. 

 (All enlarged 360 diameters.) 



