THE GROWTH OF THE SHOOT FROM THE BUD 35 



flower. If two bulbs of the dark blue Hyacinth are grown in 

 hyacinth glasses, one in the dark, the other in the light, the follow- 

 ing differences may be seen : 



1. The leaves of the one are yellow ; those of the other green. 



2. The flowers of the one grown in the dark are paler. 



3. The stem of the one grown in the light is upright, much 

 shorter and able to bear the weight of the spike of flowers, whilst 

 that of the one grown in the dark is straggling, inclined to fall 

 down, much longer and unable to bear the weight of the inflores- 

 cence. 



Exactly the same differences will be found in Nature. A 

 Dead-nettle growing in the light has shorter internodes than one 

 hidden in a hedge and more or less shaded from the light, and 

 although it may not be easy to find plants with yellow leaves in a 

 hedge, it is very usual to find them with much paler green leaves. 

 The leaves of trees in a wood show the same differences. Those 

 on the fringe of the wood are greener than 

 those in the depth of the wood, and 

 flowers carpeting a wood are often paler in 

 the thickest part of the wood than on its 

 outskirts. This is well seen in the Herb- 

 Robert. 



COMPARISON OF FOLIAGE-LEAVES WITH 

 COTYLEDONS. A little observation of 

 seedlings soon shows that cotyledons are 

 very varied. This great variety is due to 

 several factors : the size of the seed, the 

 presence or absence of endosperm, the 

 manner of folding of the cotyledons in the 

 seed, and, perhaps most of all, the shape 

 of the seed. It is obvious that narrow 

 cotyledons will fit best into long narrow 

 seeds, as in the ash and sycamore, but 

 there are very many instances of narrow 



J 1 FIG. 19. Seedling of Radish. 



seeds with broad cotyledons. In the latter, 



Lord Avebury points out that the cotyledons lie transversely 



to the seed, not lengthways as in the former case. 



