492 GRAMINE^. CEREALS 



If left longer the crop becomes dead-ripe, in which state the grain 

 is brittle when cut across or broken, and the straw loses much of 

 its brightness; if left on the field the straw also is liable to 

 become greyish and dirty in appearance, and often so brittle that 

 in certain varieties of cereals the ears may drop off whole, and 

 much of the grain be lost in handling the crop. 



For most cereals it appears to be best to cut the crop in the 

 yellow-ripe stage when no trace of chlorophyll can be detected 

 in any part of the pericarp of grains selected at random in 

 several parts of the field. 



Ex. 253. — Germinate grains of all the cereals on damp blotting-paper and 

 carefully note the number of roots which make their appearance from the 

 different kinds. Observe the way in which the plumule makes its exit from 

 the grain. Extract the embryos complete and note the shape of the scutellum 

 in each. 



Does a naked caryopsis of oat or barley germinate similarly to that of 

 wheat ? 



Ex. 254. — Carefully dig up young plants of any of the cereals and note the 

 position and number of the ' coronal ' and ' seminal ' roots. 



Ex. 255. — Make longitudinal sections of young ' untillered ' plants and 

 'tillered' ones in early spring or winter. Examine with a lens or microscope 

 and observe the number of axillary buds. 



Ex. 256. — Make similar sections when the stems are 6 or 8 inches high, and 

 note the presence and position of the young inflorescences or ' ears ' within. 



Ex. 257. — Examine an ear of wheat, barley, and oats just after it appears 

 from the uppermost leaf-sheath. Note the character of the flowers. Make 

 examination at intervals later in order to watch the growth of the caryopsis 

 between the glumes. Which grains of the ear develop most rapidly ? 



Ex. 258. — Cut across grains at various intervals and observe the different 

 changes which come over the grain and its contents during ripening. 



Note the order of disappearance of greenness from the stems, nodes, leaf- 

 sheaths, and leaf-blades. Endeavour to observe the (i) milk-ripe, (2) 

 yellow-ripe, (3) ripe, and (4) dead-ripe stages, and how they pass one into 

 the other. 



