Lignin

“ Their thick stems required, however, more strength than is necessary in their diminutive successors, and to meet this want some remarkable structures were introduced similar to those now found only in the stems of plants of higher rank. The cells and vessels of all plants consist of thin walls of woody matter, enclosing the sap and other contents of these sacs and tubes, and when strength is required it is obtained by lining their interior with successive coats of the hardest form of woody matter, usually known as lignin. ”

“ FIBRE, VEGETABLE, called also Lignine; (Ligneux, Fr.; Pflanzen-faserstoff, Germ.) is the most abundant and general ingredient of plants, existing in all their parts, the root, the leaves, the stem, the flowers, and the fruit; amounting in the compact wood to 97 or 98 per cent. It is obtained in a pure state by treating saw-dust successively with hot alcohol, water, dilute muriatic acid, and weak potash lye, which dissolve, first, the resinous; second, the extractive, and saline matters; third, the carbonate and phosphate of lime; and, lastly, any residuary substances. ”

“ The nitrogenous matter consists of vegetable fibrine, albumen, and gluteine in the rough form of gluten. The fatty matter is in no way peculiar. The non-nitrogenous carbo-hydrates are starch, dextrine, sugar, gum, cellulose, and lignine—starch chiefly. ”

“ Decay of Ligno-cellulose.—When a mass of ligno-cellulose (jute) is allowed to lie for a long period in a damp state, it undergoes resolution accompanied by structural disintegration. The soluble products of this change are acid bodies of the pectic class, and astringent substances closely resembling the tannins. In this decomposition also we have evidence of the plastic condition of the ligno-cellulose molecule, of the variety of its modes of resolution, according to the various directions in which it is attacked. ”

“ Ligno-celluloses find their chemical representative in the jute fibre. They constitute the woods, and are therefore of the widest distribution and the highest industrial utility. It is important to note that a complex having all the chemical characteristics of a ligno-cellulose occurs in a soluble colloidal form in the juice of the white currant. The formation of ligno-cellulose is the chemical equivalent of the morphological change of the plant cell known as “lignification.” ”

“ The gradual wasting of plant-tissue in the formation of peat, lignite, coal, etc., may be estimated as averaging for peat, 20 to 30 per cent.; lignite, 30 to 50 per cent.; coal, 50 to 70 per cent.; anthracite, 70 to 80; and graphite, 90 per cent. of the original mass. The evolved products ultimately represent the entire organic portion of the wood--the mineral matter, or ash, being the only residuum. These evolved products include both liquids and gases, and by subsequent changes, solids are produced from some of them. ”

“ Decompositions of Ligno-cellulose.—In addition to the specific resolutions above described which depend upon the distinctive chemical characters of the cellulose and lignone respectively, the following may be noted: to simple hydrolytic agents the two groups are equally resistant, therefore by boiling with dilute acids or alkalis the groups are attacked pari passu. Weak oxidants may also be used as bleaching agents to remove coloured by-products without seriously attacking the ligno-cellulose, which is obtained in its bleached form. Nitric acid of all strengths effects complete resolution. ”

“ The sap is to the plant, what the blood is to the animal,—the elements of nutrition and secretion are contained in it, and whatever interferes with its normal constitution by subtracting from, or adding to it, deteriorates its qualities, and retards or accelerates the functions of the individual. Excess or deficiency of the natural elements may also be a source of disturbance; if carbonic acid be too abundantly liberated in the soil, as Dr. Lindley expresses it, "plants become gorged;" and if, on the other hand, the elimination be too slow, they become starved. ”

“ Soot from wood has been found to contain, as an average, 1.36 per cent of nitrogen; .51 per cent of phosphorus and 5.34 per cent of potassium. We practice burning straw and corn stalks in enormous quantities, to get them easily out of the way, thus scattering on the winds valuable plant food, thoughtlessly and lazily wasting where these people laboriously and religiously save. These are gains in addition to those which result from the formation of nitrates, soluble potash and other plant foods through fermentation. ”

“ Indeed the evidence of biological observation goes to show that the ligno-celluloses are formed, by a process of chemical modification, from some more purely cellulosic tissue, which preceded it, and with this modification there is, nevertheless, a retention of the general features of the original cellulose. In the domain of animal chemistry, recent investigation has also shown that the development of proteid tissues finds its chemical expression in their aldehydic characteristics, or as it has been put, the immediate physical cause of life is to be found in the chemical tension of aldehydes. ”

“ Lignite, in considerable quantity, exists among the tertiary deposits of the Alps, and has recently been found in the north-west provinces of India, in the vicinity of Kalibag; but all partaking of the usual qualities—wood, only partially altered by inhumation, and imperfectly adapted for domestic purposes.
One overwhelming consideration with us, in the discussion of [130] this question, is the position which man occupies, and the part he now plays on the theater of creation. The beasts and quadrupeds of the earth do not appear to have been formed so early as the carboniferous epoch. ”

“ In the old pharmacy the products of destructive distillation of guaiacum wood were known as Oleum ligni sancti. It must have consisted of the substances which we mention further on in the following article.
Description—The wood (always known in commerce as Lignum Vitæ) as imported consists of pieces of the stem and thick branches, usually stripped of bark, and often weighing a hundredweight each. It is remarkably heavy and compact. Its sp. gr. which exceeds that of most woods is about 1·3. ”

“ Nitrogen, which is the most important plant-food that may be absent from dry-farm soils, may be secured by the proper use of leguminous crops. All the pod-bearing plants commonly cultivated, such as peas, beans, vetch, clover, and lucern, are able to secure large quantities of nitrogen from the air through the activity of bacteria that live and grow on the roots of such plants. The leguminous crop should be sown in the usual way, and when it is well past the flowering stage should be plowed into the ground. ”

“ The lignite-beds furnish the fuel, the slow-paced erosion lays the fuel bare, spontaneous combustion supplies the torch, and the whole phenomenon is explained.
That the lignite is in some way connected with the fiery metamorphosis of the Bad Lands we might have inferred from the fact that no lignite ever appears above the burned belts, and in a hill entirely burned the lignite is entirely wanting. The burned clay also corresponds in position to beds overlying the coal in hills immediately adjacent. ”

“ Experiments at Rothamsted and elsewhere, as well as everyday practice of the farm, bear testimony to the paramount importance of nitrogen-supply, and to the crops it is capable of raising. This applies not only to corn crops of all kinds, but to root crops, grass, potatoes, &c. Leguminous crops alone seem to have no need of it. In view of this practical experience, Liebig’s “mineral theory”—according to which he laid down that plants only needed to have mineral constituents, such as phosphoric acid, potash and lime, supplied to them—reads strangely nowadays. ”

“ These lignites or modern coals are only peat beds which have been buried for a longer or shorter time under clay, sand, or solidified rock, and have progressed farther or less far on the road to coal. As with peats, so with lignites, we find that at different geological levels they exhibit different stages of this distillation--the Tertiary lignites being usually distinguished without difficulty by the presence of a larger quantity of combined water and oxygen, and a less quantity of carbon, than the Cretaceous coals, and these in turn differ in the same respects from the Triassic. ”

“ If that be greater, so is this; as in Plants is common; the Lignous Body being usually so far dilated, that the utmost shootings thereof may easily be seen to jut out, and adjoyn to the Skin. And if the Sap be still of greater energy, it so far dilates the Lignous Body, as not only to amplifie the Pith and all its Pores; but also so far to stretch them out, as to make them tear. Whereupon either running again into the Cortical Body, or shrinking up towards [84] it, the Trunk thus sometimes becomes an hollow Stalk, the Pith being wholly, or in part voyded. But generally it keeps entire ”

“ Pecto-celluloses are so named because the associated substances—carbohydrates, together with their oxidation products, i.e. containing either two carbonyls (CO) in the unit group or carboxyl (CO·OH) groups in a complex—are readily hydrolysed by weak acids to the gelatinous “pectic acids” or their salts. Ligno-celluloses are the substances of lignified tissue, the non-cellulose constituents of which are characterized by the presence of benzenoid and furfuroid groups; and although essentially complex, they may be regarded as homogeneous, and are conveniently grouped under the name lignone. ”

“ Storing Nitrogen.—Man needs protection from his own greed, and nature's checks are his salvation. An illustration is afforded in the case of legumes grown for the maintenance of soil fertility. The clovers and some other legumes are seeded primarily for the benefit of the soil. The need of organic matter is recognized, and a cheap supply of nitrogen is wanted for other crops in the rotation. The purpose of the seeding is praiseworthy, but if all of the product were available for use off the land, observation teaches that the soil producing the crop probably would fare badly. ”

“ By growing any of the class of crops called Legumes we may add to the soil not only humus but also nitrogen. Cowpeas, beans, clover, vetch and plants having foliage, flowers, seed pods and seeds like them are called Legumes.
Most of the farm plants take their nitrogen from the soil. This nitrogen is taken in the form of nitric acid and nitrogen salts dissolved in soil water. The legumes, however, are able to use the free nitrogen which forms four-fifths of the atmosphere. This they do not of their own power but through the aid of very minute plants called bacteria or nitrogen-fixing germs. ”

“ They are occasionally adulterated with boxwood shavings. Lignum vitae is imported chiefly from St Domingo, the Bahamas and Jamaica.
The bark was formerly used in medicine; it contains much calcium oxalate, and yields on incineration 23% of ash. Guaiacum resin, the guaiaci resina of pharmacopoeias, is obtained from the wood as an exudation from natural fissures or from incisions; by heating billets about 3 ft. in length, bored to permit of the outflow of the resin; or by boiling chips and raspings in water to which salt has been added to raise the temperature of ebullition. ”

“ Thus, with a few established facts in mind, one can easily determine how to maintain or even to increase the supply of nitrogen in the soil, and without the purchase of nitrogen in any form; and it is just as possible and just as necessary thus to provide the nitrogen needed in grain farming as in livestock farming. When we consider that animals destroy two-thirds of the organic matter in the food consumed we find that as between the two systems above described the organic matter or humus of the soil will be better maintained in the grain system outlined. ”

“ An Excess of Nitrogen.—Too much nitrogen, due to heavy manuring or other cause, produces an excessive growth of stalk or straw, at the expense of grain production, in the case of corn, wheat, and other cereals. It produces a rank growth of potato vines and partial failure of the crop of tubers. It produces a tender growth of straw or vine that invites injury from fungous diseases. It is the rule that soils have a deficiency in nitrogen, but when there is an excess, the best cure comes through use of such crops as timothy, cabbage, and ensilage corn. ”

“ The enlargement at the ligule is abrupt. The base widens gradually to about 2 cm. but is much thinner than in the short species. In the upper part of the petiole the reverse is true, the cross section of the leaf-stalk of the Thrincoma being almost diamond-shape, while that of Thrinax is merely lenticular.
4. These differences of proportion of ligule and stalk are obviously correlated with the different habits of the two species. The shorter and more robust trunk of the one enables it to withstand the strain of the relatively limited exposure to the wind. ”

“ Leguminous Crops and the Acquisition of Nitrogen.—The fact that the growth of a leguminous crop, such as red clover, leaves the soil in a higher condition for the subsequent growth of a grain crop—that, indeed, the growth of such a leguminous crop is to a great extent equivalent to the application of a nitrogenous manure for the cereal crop—was in effect known ages ago. Nevertheless it was not till near the approach of the closing decade of the 19th century that the explanation of this long-established point of agricultural practice was forthcoming. ”