368 



KNOWLEDGE. 



October, 1913. 



stores up in all its organs is considerably larger and more 

 durable than that of any tree in our sylva. The beautiful 

 Beech exhibits a distinctive variation in this respect, inasmuch 

 as even in January and February its wood is very rich both in 

 oil and starch, every cell in the parenchyma of the outer rings 

 being full of starch (not the case in most starch-trees), and 

 this remains up till April, when the wood is still rich in oil (in 

 fat-trees there is little oil in spring or summer). In the Beech, 

 too, the wood becomes lignified very slowly ; the quantity of 

 tannin produced here and elsewhere is relatively small ; it lays 

 up a store of starch in the inner rings in a rare manner, and 

 it requires more nitrogen, potash, and lime than many other 

 trees. " The whole tree " says Wicke, " sticks, so to speak, in 

 a siliceous coat of mail, the silica forming a thick solid crust 

 over the whole stem and the young twigs " (the actual white 

 colour of the bark is, however, due to lichens). The pure ash 

 of the bark contains up to ninety per cent, carbonate of lime, 

 indicating an enormous affluence of acids, mainly oxalic. The 

 chief difference between Beech and Oak, as revealed by the 

 chemistry of their leaves, is that the latter is more vivacious 

 than the former : the Oak has much more tannin and 

 carbohydrates, and its protein falls off in greater amount 

 towards autumn, at which time also the quantity of silica in 

 its ash is little over half of what it is in that of the Beech ; 

 this latter tree, however, evolves more fat-oil, its ripe nut 

 containing some twenty per cent, thereof, while the acorn 

 produces only about six per cent, at most. This various 

 outcome of these two constituents seems referable to the 

 varying capacity of the two trees to withstand the effects of 

 external conditions of weather, and so on. 



We now approach the Ash (Fraxinus excelsior) with its 

 smooth bark and knotty protuberances; and it must be 

 confessed that it is difficult to render full justice to its perfec- 

 tion of organisation and to its wonderful wealth of chemical 

 constituents. In fact, we here enter upon a new chapter in 

 the chemistry of the forest. In 1856 Prince Salm-Horstmar 

 discovered in the infusion of the bark a peculiar fluorescence, 

 and in 1857 he isolated and examined the substance causing it 

 and named it fraxin. Its dilute aqueous solution with a trace 

 of alkali exhibits by reflected light a strong bluish fluorescence, 

 due to the absorption of certain rays. It is a colourless 

 crystalline glucoside perhaps derived from cinnamene. The 

 tannin of the Ash totally differs from that of any of our native 

 or denizen trees, the Holly excepted. In fact, it is identical 

 with the tannin of coffee, and is accompanied by a tannoid 

 whose dun shades with alkalies produce the blackish Ash 

 leaves in the fall. Ash leaves, indeed, may be ranged among 

 the wonders of British botanical chemistry. They rival the 

 Oak in the manufacture and storage of starch, but far surpass 

 it as respects carbohydrates, such as mannite, inosite, and 

 also malic acid, malates, and mineral matters, but have not so 

 much wax, fat, carotin, tannin, or mucilage. The difference 

 in this case arises from the nature of the protoplasm, or of its 

 behaviour. While, on the one hand, the products of assimila- 

 tion are only somewhat different, on the other hand the 

 products of deassimilation exhibit a marked variation. Thus, 

 while the tannin of all the trees hitherto considered contains 

 what is called a phloroglucin nucleus, that of the Ash has a 

 quinol nucleus, and, moreover, it is linked on to the derivatives 

 of a hydrocarbon which indicate that a larger number of 

 carbon and hydrogen atoms are relinquished on the disrup- 



tion of the albuminoid molecule. This means that the pro- 

 cess of oxidation in this particular direction is carried in the 

 Ash leaf to a loftier pitch than is the case with regard to the 

 preceding organisms in our review. The Ash is a tree of 

 great soil consumption, and its leaves retain their vitality up to 

 the first frosts, the ash therein amounting to 10-5 per cent, in 

 dry matter with 45-8 per cent, of lime. Curious how it is 

 that this tree sucks up no manganese from the soil, while 

 closely contiguous plants and trees may absorb a great deal. 



The lordly Sycamore and some of its allies remain to be 

 considered. The chemistry here is comparatively simple. 

 They are all starch trees, but at the same time are rather 

 oily. Thus there is a lavish plaster of wax on the lower 

 epidermis of the leaves of a Sycamore. Its bark is very poor 

 in tannin, and has no resin apparently, but a saponin-like 

 substance, very much oxalate of calcium, and 9-4 per cent, 

 of ash are found here. Its vital powers awaken early in the 

 year, for concurrently with the regeneration of the starch in 

 spring a quantity of cane-sugar (rising mainly from the roots 

 or base of the trunk) becomes dissolved in the cell sap, which 

 thereby gains sufficient tension to bleed out through the bark 

 if pierced. The adult leaves have no reserve of starch, 

 having no true chromoplasts, but contain much carotin, wax, 

 and albuminoids at all times, also a good deal of tannoid and 

 tannin, only a little sugar or mucilage, but much oxalate of 

 calcium almost from birth, and 11-2 per cent, of ash, which 

 even on 8th August yields 14-9 per cent, silica. The fact 

 that in the leaves the production of starch declines towards 

 the autumn, while the cellulose does not increase, the 

 albuminoids and sugars remain uniform till very late, and 

 there is a heavy fixation of silica and lime in the old tissues, 

 indicate the rapid growth and early decline of vitality of these 

 organs. That well-known ally, the Horse Chestnut, exhibits 

 a similar chemistry, except that its fruit contains starch and 

 saponin, and its bark yields the brilliantly fluorescing aesculin 

 discovered by Canzoneri in 1825. The tannin of these 

 Aceraceae is especially competent to evolve very brilliant 

 crimson tints, as is seen in the American Maples in Autumn, 

 but our species, alas ! are precluded from this beauteous 

 display by reason of the sharp weather fangs that cause a 

 premature demise of their external tissues. 



By way of summary it may be concluded that starch trees 

 are Elm, Oak, Ash, Sycamore; fat-trees are Birch, Alder, 

 Linden, Scots Pine, Holly. The richest in starch, but having 

 less chlorophyll, are Birch, Ash, Elm, Scots Pine, Oak ; poorer 

 in starch, but having more chlorophyll, are Beech, Sycamore, 

 Alder, Poplar, Rowan. As to nitrogen the leaves of Alder, 

 Elm, Beech, Willow, Linden, Sycamore, contain most ; while 

 those of Oak, Hazel, Poplar, Ash, have less, as against those 

 of Birch and Scots Pine, which contain the least. Trees rich 

 in waxy and fatty matters are Scots Pine, Sycamore, Beech, 

 Alder, Birch ; while Oak, Ash, Elm, Poplar, Holly, produce 

 one half or less thereof. The greatest proportion of lignin or 

 crude fibre is found in Scots Pine, Oak, Sycamore, and 

 rather less in Ash, Elm, Birch, Alder, and Hazel. Alder and 

 Oak produce the most tannin ; there is much less in Beech, 

 Elm, and Poplar. The mineral matters of the soil are most 

 strongly absorbed by Elm, Sycamore, and Ash, while the other 

 trees flourish with vigour in most cases on a much sparer diet 

 of that sort. 



SAGACITY OF A DOG. 



Mr. James Saunders, of Luton, contributes the following to 

 The Selborne Magazine : — 



" There were two terrier dogs, a black smooth-coated one, 

 and a rather larger white one. The latter was in the water 

 by his own desire, where he was enjoying himself. The black 

 one slipped off the stone coping and had an involuntary bath. 

 He tried to extricate himself by striving with his fore-paws to 

 gain the top of the coping, but the sides of the lake were so 



perpendicular that his hind feet could get no grip. He 

 partially succeeded several times, but always fell back till he 

 showed evident signs of distress. In the meantime the white 

 dog had left the water by the shallow river bed, and at once 

 went to see what the other dog was doing. He soon realised the 

 gravity of the situation and tried to grab the black dog by the 

 neck. In this he failed several times, but at last got some of his 

 teeth under the other dog's collar and hauled him out instantly." 



