ACORNS 61 



certain that no light at all is present in the upper stratum 

 of the soil ? For it is the plumule that needs it, the first 

 leaves that seek it and these are frequently green before 

 they emerge from the soil ; so sometimes is the plumule. 

 We should, I think, be slow in accepting the dictum that 

 light, in the sense of an illuminating power, is alone respon- 

 sible for the formation of chlorophyll and look rather to 

 light-frequencies and the energy possibly accompanying 

 them to further explain the phenomenon. Can we say with 

 certainty that this energy, if it exists, is incapable of pene- 

 trating the soil ? Or if the answer is " No," Hmit the depth 

 of such penetration ? 



Next we will take the matter of the protection of the 

 young buds from light, or I should prefer to say, from hght- 

 energy ; disregarding provisions against possible enemies. 

 Generally such protection is afforded by colour, varying 

 from pink to crimson and russet-brown, but in some plants, 

 such as the Oak, the colouring may include the whole of the 

 leaves of the seedhng if grown in the open ground ; those 

 in the diffused light of the greenhouse showing clear chloro- 

 phyll only, though a more dehcate part of the plumule may 

 be tinted. The buds of the Oak are protected by dry, brown 

 stipules. 



The phenomenon is particularly noticeable in the case of 

 such ferns as the Maidenhair which have been forced. If 

 on a bright day in the early summer one of these is removed 

 from the greenhouse and placed in the open air in the full 

 glare of sunlight the younger fronds turn, or come up, red, 

 but later, when the fronds are stronger, this colouring gradu- 

 ally changes to the familiar green. 



" In other cases," Lord Avebury remarks, in Buds and 

 Stifules, " buds are protected by gummy or resinous secre- 

 tions, as in the Horse Chestnut (^sculus), the Poplar (Popu- 

 lus), Hazel Nut (Corylus), Honeysuckle (Lonicera), Currant 

 (Ribes), Lilac (Syringa), Hornbeam {Carpinus), Elder 

 (Sambucus) and Alder (Alnus), in many herbaceous plants 

 {Viola, Helianthus, Salvia), and most conifers. 



"The gum is often confined to the outer surface, the. 

 interspaces between the leaves being filled by hairs. 



