20 A'eco-afi : The Wych Elm. 



40.8 lime. Silica-containing rosettes of cells surround the 

 epidermal hairs whose walls are also imprej,mated with silica, as 

 are also some of the walls of the epidermis ; while crystals of 

 oxalate of calcium occur in the nerves and druses of same in 

 the mesophyll. 



Flower and Fruit. — The flowers are disposed in loose 

 clusters or in simple umbels, and most of them are male by 

 abortion ; they all open nearly simultaneously, and fertilisation 

 is effected all at once in each umbel, soon after which they fall 

 to earth. The dried flowers contain about 20 per cent, albu- 

 menoids and 8 ash, which has 29.2 per cent, potass, 14 lime, 

 11 P-O^, and 16.3 SO^. The fruit is a samara with peripheral 

 wing's ( = a wing-ed achene), i.e., the external epidermis expands 

 into flattened prolongations in the form of wings ; the interior 

 remains empty for some time, but is rapidly filled up by the 

 developing embryo, which has tuberous cotyledons with cellulosic 

 cell-walls, nerves in the procambial state, and aleurone and oil, 

 but no starch ; the radicle is superior, and there is no endosperm. 

 The histological composition of the ripe fruit is obscure, the 

 various original parts having become fused, or some of them al- 

 together obliterated. The chemistry, however, is of great interest. 

 The dried fruit and seed yield 8.3 per cent, of a fluid oil which is 

 mostly of olein giving with mineral acids dark greenish-brown 

 colours and a pale yellowish elaidin ; also considerable resin, 

 some sugar (glucose and levulose), traces of tannoid, a very 

 large quantity of mucilage with much oxalate of calcium, but no 

 phloroglucin, and no starch ; the ash amounts to 9.9 per cent., 

 and contains 30.9 per cent, soluble salts, 14.6 silica, 24.3 lime, 

 4.7 magnesia, 8.5 P-O^, and 3.3 SO*. It will be observed that 

 the amount of silica in this fruit is quite unique among our 

 forest trees, and is probably connected with the great, rapidity 

 which marks the maturation of the organ. The thin extended 

 surface of the winged epidermis off"ers facilities for rapid evapo- 

 ration and the drainage of silica thereto from other parts. 



Summary. — An eminent peculiarity of this tree is the highly 

 developed system for the conduction of water — the spacious 

 vessels in the wood, the numerous lacuna; in the leaves, etc. 

 The physiological processes are characterised as languishing, 

 and so far imperfect; the increase of lignin, cellulose, and starch 

 is slow, the albumenoids and the soluble carbohydrates show 

 few symptoms of exhaustion, and the fixed insoluble matters 

 tend to accumulate in a very marked degree. The young stems 

 cease to g-row at an c-arly period, the \('getati\e development 



Naturalist, 



