Keegan: The Hazel (Corylus avellana). 



youth, and has when mature about 150 stomata per square 

 millimetre; the vascular bundle system of the lamina is closed 

 (not open as in Birch). This structure indicates a considerable 

 protective safeguarding- against excessive transpiration, rather 

 than great assimilatory energy ; and the leaf being rather thick 

 it absorbs much heat. The young leaf contains a considerable 

 amount of carotin, with moderate amounts of wax, fat, and 

 resin, which remain throughout most of the life of the organ. 

 Rutin is present with a benzene group not detectable in allied 

 genera, and the tannin amounts to about 5 per cent, in autumn. 

 Free phloroglucin occurs in nearly all the epidermal cells and in 

 the mesophyll. A special feature is the presence of inosite. At 

 the end of July — the period of mature development of the leaf- 

 it contains in dry about 14-5 per cent, albumenoids, 65*8 non- 

 nitrogenous matter, 14*5 fibre, and 6-3 ash. The ash presents 

 some remarkable features. The proportion of soluble salts 

 therein is comparatively small (about 30 per cent, at most). At 

 the end of Jul}' there is 18 per cent, soluble salts, 4*2 silica, 

 30-4 lime, 7 magnesia, 4-5 SO :1 and 77 P' 2 0 5 ; iron and man- 

 ganese are present in some cases in considerable quantity ; in 

 the autumn the silica rises to about 15 per cent., and the 

 phosphorus sinks to 3*9 P 2 0 5 . This composition clearly indi- 

 cates a sparse production of carbohydrates, and forsooth this is 

 a palpable feature in the analysis of the leaves, and is doubtless 

 incidentally connected with the powerful evolution ot fatty 

 matters in the seed. 



Flower and Fruit. — The Hazel is the most precocious of 

 all our flowers of the forest. The bracteal scale of the male 

 catkin is clothed with hairs, and its epidermal cells have 

 infolded walls. The ovary encloses two loculi with one ovule 

 in each, and is surmounted by two long styles of a purple-red 

 colour. The nut is a one-seeded achene resulting by abortion 

 from the bilocular ovary. Its pericarp is composed of an 

 epidermis studded with fine hairs, below which a layer of 

 roundish cells occurs with moderately thin walls arranged 

 tangentially ; these cells gradually give way to large oblong 

 radially disposed cells with very stout walls pierced by numerous 

 very fine pore canals, while towards the interior the thickening 

 of the wall is so augmented that finally nothing is left but an 

 almost solid mass with merely a very small cavity within, The 

 hard, dry, tooth-cracking nut is, therefore, constructed of a highly 

 lignified cellulosic skeleton or framework, not strengthened by 

 anv serious intermixture of mineral matters, but solely the result 



1902 October i. 



