THE SEEDLING 13 



Rice; in other words, the former group of plants 

 produces a tap-root, and the latter a bunch of fibrous 

 roots. 



If the seeds that have germinated are so placed that 

 their roots point upwards and stems downwards, it 

 will be found soon that the growing tips of the roots 

 curve downwards and the growing tips of the shoots 

 curve upwards, thereby assuming their normal posi- 

 tion. The roots seem to have an innate tendency to 

 grow down into the soil — avoiding light, — and the 

 stems to grow up in the air — seeking li'ght. 



For purposes of germination, seeds require a suit- 

 able amount of heat, moisture, and air, and these 

 conditions are ordinarily present in the soil. Too 

 much or too little heat or moisture and absence of air 

 in the soil prevent germination. Moreover, seeds 

 require to be screened from light, as light retards 

 germination, and this condition is secured in seed- 

 beds. When these conditions are satisfied, the food 

 materials stored in the seeds, either in the embryo or 

 outside it, as the case may be, undergo chemical 

 changes which render them soluble and available for 

 the embryo. The embryo, thus nourished, grows into 

 a seedling, as described above. In Pea, Gram, and 

 dais or Pulses generally, the seedlings grow at the 

 expense of the food materials stored in their thick, 

 fleshy cotyledons. Hence it is that Pulses have been 

 selected as food-graims by human beings all over 

 the civilized world. As these cotyledons are hinged 

 at the axis of the shoot of the embryo, the food 

 materials pass directly from them to the shoot. In 

 Rice, Wheat, Barley, Maize, and Cereals generally, 

 the seedlings grow at the expense of the food materials 

 stored in the endosperm. As the endosperm is 

 situated outside the embryo, the cotyledon in these 



