COTYLEDONS. 



G07 



level of the seed (figs. 141 '* and 141 '*'). Here long root-fibi-es 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 Seedlings. 



1 Seedling of the Nasturtium {Tropaeotum vuijus). 2 xhe same at an earlier stage of development. * Water Chestnut (Trapo 

 natajig), from which the embryo is emerging. * Later stage of development. * Young seedling of the Austrian Oak 

 iQuerciu Atialriaca). « The same, further developed ' Seed of the Date (Phoenix dactyltfcra) from wliich the cmhi-yo is 

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

 in longitudinal section. '<> Older Date in longitudinal section. " Seed of the Reed-mace Typha Shulttewurlhii. 

 " The same with protruding embryo. " The same at a later stage of development. », '5 Seedling of the Sedge Carex 

 vulgarit. Kig. 1-8, natural size ; 9, 10, x 8 ; 11-13, x 4 ; 14, 15, x 8. 



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 dnuvu out from the emptied seed-coat. All this occui-s underground. 

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



