COTYLEDONS. 



607 



level of the seed (figs. 141 ^^ and 141 ^^). Here long root-fibres develop from the 

 radicle and from the base of the hypocotyl; these burst through the cotyledon, 

 grow down into deeper layers of earth, and fix the young plants in the spot 

 where the cotyledon has placed it. The apex of the cotyledon remains in the 



Fig. 144.— Germinating Seeds and SeedlingB. 



' Seedling of the Nasturtium {Tropmolum majus). 2 xiie same at an earlier stage of development. » Water Chestnut (Trapo 

 nataiis), from which the embiyo is emerging. ♦ Later stage of development. « Young seedling of the Austrian Oak 

 (Quercus Austriaca). 6 The same, further developed i Seed of the Date (Phoenix dactylifera) from which the embryo is 

 emerging. 8 The same eight weeks later, after the seedling has already developed root and scale-leaves. 9 Young Date 

 in longitudinal section, ic Older Date in longitudinal section, n Seed of the Reed-mace Typha Shuttle worUiii. 

 12 The same with protruding embryo, is The same at a later stage of development. ", is Seedling of the Sedge Carex 

 vulgaris. Fig. 1-8, natural size ; 9, 10, x 8 ; 11-13, x 4 ; 14, 15, x 6. 



seed, and here absorbs the last remnants of the reserve-materials. When these 

 are at last exhausted, one limb of the bent cotyledon grows upwards, and its 

 apex is drawn out from the emptied seed-coat. All this occurs underground. 

 Now the cotyledon also has to reach the sunlight and become green. This is 



