104 Keegaji : The Sycauiorc. 



nucellus, immediately borders the foliaceous wrinkled coty- 

 ledons ; there is no endosperm ; it ripens in September, and 

 about half of the seeds produced are fit to germinate up till two 

 years. The whole fruit contains about 8 per cent, of water, 

 26 albumenoid, 8 to 10 fat-oil, 2 sugar, 9.5 fibre, considerable 

 resin and oxalate of calcium, 5.5 ash, which has 37 per cent, 

 soluble salts, 2.6 silica, 25.7 lime, 4 magnesia, 8 P^0■^ and 

 3.6 SO-'^. The reserve materials are aleurone and oil, no starch. 

 When the fruit covers are transparent, so that light can easily 

 enter into the deepest parts of the seed, then a dense homoge- 

 neous protoplasm, coloured uniformly green, fills the cells of the 

 embryo. This green pigment was formerly thought to be chloro- 

 phyll, but it is doubtful if this seed-green is really identical 

 M'ith or related to leaf-green. 



Summary. — There is some similarity between the physiology 

 of the Beech and that of the Sycamore, but in the latter we have 

 to deal with a case of palmate nervation of the leaves. With 

 regard to these organs, we have all the chemical evidence of 

 rapid growth and early decline. The production of starch 

 declines towards the autumn, that of cellulose does not increase, 

 and complete lignification is not consummated till the fall ; 

 the albumenoids and the sugars remain uniform till very late, 

 and there is a heavy fixation of ash with much silica and lime 

 in the old leaf. K special feature is the large quantity of wax 

 coating on the lower epidermis, the cause of which is difficult 

 to assign, but is doubtless connected with a decline of the 

 vitality on that side of the organ. The transpiratory activity 

 is only moderate, and the assimilatory energy is not as great 

 as the sombre green of the foliage would seem to indicate. As 

 regards the stem, the thickness of the liber relatively to that 

 of the wood in older trees is comparatively feeble, which is a 

 sign of defective differentiation ; and notwithstanding that the 

 wood is very fibrous, the lignification of that particular element 

 is very slow, and not completed up till about 80 or 100 years. 

 Moreover, the felled timber is liable to rot when exposed to 

 atmospheric variations— a circumstance which is attributable 

 to a serious deficiency of tannin and resin. However, notwith- 

 standing all these grave drawbacks, the Sycamore manages to 

 endure well and hearty for over two hundred years. That it 

 somehow maintains a remarkable soundness of main body and 

 limb is clear from the fact that it is not subject to maladies like 

 gummosis, or to a partial demise of any of its twigs and young 



Natuia-ift, 



