SEEDS AND SEEDLINGS. 



49 



Wheat germinates more readily than Maize, at compara- 

 tively low temperatures, but the seedlings of both should be 

 studied. In Wheat note the groove running down one side, 

 opposite the embryo. The shield- like body which in these 

 seeds lies on one side of the radicle and plumule is, apparently, 

 the single cotyledon, and its function is to secrete diastase, in 

 order to digest the food stored in the rest of the seed, and to 

 pass it on to the growing root and shoot. Note the colourless 



Fig. 26. Maize. A, B, two views of outside of grain ; C, grain cut longitudinally ; 

 D to G, stages in germination. 



sheath which protects the young shoot and through which the 

 foliage-leaves emerge ; and the grass-like leaves with parallel 

 veins. 



The starch-containing part of the Maize or Wheat grain is 

 something not represented in any of the seeds we have studied 

 so far. It is called the endosperm. Seeds like Maize and 

 Wheat are said to be endospermic, because in addition to the 

 young plant, which is present in all seeds, there is in this case 

 a special region in which the reserve food is stored. Seeds 

 which do not include endosperm, and in which therefore there 



8. B. 4 



