THE SHOOT 47 



these delicate leaves are others more sturdy, while the 

 exterior ones are frequently quite dry and hard and in 

 many cases covered over by a sticky substance. Some 

 of those in the interior are in many cases covered with 

 thick coatings of hairs, forming a downy pad of material 

 calculated by its non-conductivity to keep out the cold. 



If the bud is small, it will be found to contain only a 

 few leaves, perhaps only two or three; even in this 

 case, however, the general arrangements are the same. 



If we compare the apices of stem and root, we see 

 how the surroundings in each case have influenced the 

 structure. The root apex is specially protected against 

 damage from contact with hard or rough materials while 

 penetrating through the soil ; the stem is exposed to no 

 such danger, but shows a careful protection from frost 

 and wet, and undue evaporation. 



The young leaves are thus merely flattened boat- 

 shaped expansions curling over the apex of the stem. 

 Later, when their protective powers are no longer 

 called for, their adult forms are assumed. 



The leaves bring about their curving over the apex of 

 the stem in the bud by an irregularity of growth. When 

 the little swelling first appears on the growing cone it 

 is itself rounded or conical; it soon becomes laterally 

 flattened and for a time, so long as it is in the bud, its 

 under surface grows faster than its upper one, so that it 

 is made to curve forwards. When it escapes from the 

 bud later it reverses this distribution of growth and 

 grows more rapidly on its upper face, so becoming flat. 



Buds always terminate the ends of normal growing 

 shoots ; indeed the bud-form is always assumed by the 

 apex of the shoot as soon as its growth is suspended by 

 unfavourable conditions. The buds which appear in 

 the axils of the leaves lower down on the stem are the 

 commencements of the secondary shoots or branches, 

 which will elongate in due course. 



