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snow-clad summit of Peerpunjal, is described as being of an oval form, encircled by mountains clothed with vegetation, which are themselves girded by a higher range covered with snow. The level of the valley is of considerable extent, being about 60 miles in length, and 40 in breadth; its elevation is estimated by the late lamented traveller M. JACQUEMONT to be 5248 to 5576 feet; he, however, states that the beauty of this valley has been much exaggerated, both by his countryman, BERNIER, and by Mr. FORSTER. But there is no doubt that in consequence of its being copiously watered by numerous streams, lakes, and canals, there is considerable moisture both of soil and climate, and almost constant verdure; [he knew not of the late famine:] while the numerous gardens, and the great variety of fruit trees, and of beautiful flowers, must always strike visitors from the arid plains of India, whether Europeans or Asiatics, as Abul Fuzl. From the mixed nature of the cultivation, the climate must evidently be mild and temperate, for even in the warmest months of summer, the breezes which descend at night from the mountains are always cool and pleasant: the periodical rains consist of gentle showers, and the snows which fall in winter cannot remain long on the ground. The Flora of Cashmere has a great resemblance to that of European countries, but the moisture of the climate and its mild temperature in the season of vegetation, causes so great an extension of the herbaceous parts, as well as of the flowers of plants, that many of them rival in luxuriance those of tropical countries." The mildness and moisture are indicated by the culture of rice, melons, gourds, and cucumbers. The kidney. bean thrives well-also the egg-plant, capsicum; marsh-tree mallow, wheat, barley, saffron ; turnip, raddish, beet-root; clover, &c. Of trees, the walnut, aspen, poplar, plane, and willow are named as most common. Fruit trees are so common as to constitute a jungle.

The author passes under review, also, the valley of Nipal-the several river valleys and passes of the great chain-Kunawar, Bussahir, &c. He even digresses to the Neelgherries of the peninsula, to show that a similarity exists in its vegetation and climate with that of the lower ranges of the northern chain; but we must now close our imperfect sketch of the contents of this first number, regretting only that we are from our ignorance of the science so little able to select and set before our readers the points which must have the greatest value in the eyes of a Botanist. Every Botanist in India will, however, possess the work; and possessing, prize it.

2.—Analysis of the Edible Moss of the Eastern Archipelago. By W. B. O'Shaughnessy, M. D. Asst. Surg. H. C. S.

The third number of that meritorious work, the India Journal of Medical Science, contains an able analysis of this curious delicacy of the Chinese materia culinaria, the substance of which we venture to transfer to our pages, as coming properly within the scope, to which the motto on our title page confines, or rather extends, our investigations.

The edible moss is a small and delicate fucus, of a white colour, and flattened filiform shape. The longest of the separate individuals in the specimens examined by Dr. O'S. did not exceed two inches from the ciliary processes, corresponding to the root, to the extreme of the ramifications, which were not very numerous or regular. Dr. O'S. names it the fucus amylaceus, from its remarkable and important peculiarity of containing a large proportion of pure starch.

Digestion in cold water for 24 hours separated a portion of gum, and the soluble alkaline salts:—this branch of the analysis proved it to differ from the Iceland

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moss in containing no bitter principle. Another portion was cut into very minute shreds, and boiled for 24 hours in distilled water, which was renewed as fast as it evaporated. On cooling, the liquid gelatinized, holding suspended an abundance of the undissolved ligneous shreds. The jelly was transparent and colourless; neither acid nor bitter; gave no precipitate with tincture of galls, and only a transitory blue tinge with iodine. The ligneous fibre yielded a trace of wax on boiling in alcohol; after which, ground to a fine powder, and boiled in distilled water, the solution struck a fine deep blue with iodine, from the starch present: scarcely a particle of the starch can be taken up by simple boiling until after trituration. The woody fibre incinerated gave a small residuum of earthy salts and iron. The quantitative composition deduced from Dr. O'SHAUGHNESSY's analysis is as follows:

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With regard to the best mode of rendering the moss available as an article of diet, we extract the following judicious observations :

"In the first place, from the tendency of pectin or vegetable jelly to form insoluble compounds with saline and earthy bases, it is necessary to steep this fucus for a few hours in cold rain water as the first step in its preparation. This removes a large portion, if not the entire, of the sulphate of soda, leaving all the gelatine and starch. It should next be dried by the sun's rays, and ground to a fine powder : I say ground, for cutting or pounding, however diligently or minutely performed, still leaves the amylaceous globules so mechanically protected, and so closely involved in an external sheath of tough ligneous fibre, that scarcely a particle of the starch can be extracted by boiling, even though the decoction is prolonged for several hours. When ground, boiling for 25 minutes or half an hour dissolves all the starch and gelatine. The solution while hot should be passed through muslin or calico, and thus the ligneous fibre is removed; lastly, the strained fluid should be boiled down till a drop placed on a cold surface gelatinizes sufficiently.

"With milk and sugar, and flavoured with lemon juice or sherry, this substance when prepared as I direct, would afford the invalid a pleasant article of diet, especially at sea, where other jellies or their materials cannot be so easily preserved. As I am informed that this fucus is found abundantly on the eastern coast of Bengal, I entertain considerable hopes of its being hereafter found available also in several processes of art and in various manufactures."

The wide field of vegetable chemistry has been hitherto nearly untrodden in India; and yet there is no country where it offers a richer harvest of curious and novel results. We hope Dr. O'SHAUGHNESSY's talents, once directed to the subject, will be fixed on this difficult branch of chemical analysis. He has already acquired in England the peculiar skill and experience in recognizing and separating the numerous and complicated principles of which organic substances are composed, that alone can give confidence in such analyses, and ensure their general acceptance by chemists.

XI.-EUROPEAN SCIENCE.

De Candolle's Theory of the Rotation of Crops.

It is a well-established fact in the practice of husbandry, that a succession of the same kind of crops on the same piece of ground, deteriorates not only the ground, but the crops. Thus, a successive crop of wheat, barley, or oats, on the same land, destroys the stamina of the ground, and renders each succeeding crop less in produce and value. A succession of wheat, barley, and oats, frequently repeated, will produce the same effect, though not so quickly. Even a succession of green crops will affect both the crops and the soil in a similar manner, in a given time.

This deterioration of soil and crop, is most perceptible when there is no intermediate application of manure. Manure will, no doubt, protract the period of greatest deterioration; but manure cannot constantly maintain a profitable re turn from a succession of the same kind of crop. Besides, it is impossible to obtain a sufficient quantity of manure for frequent intermediate applications, in order to counteract all the effects of deterioration. The impossibility of maintaining to perfection the same kind of vegetable on the same piece of ground in a well cultivated garden, illustrates, in a striking manner, the limited powers of In the field, where the cereal crops always ripen their seed, the power of manure is still more limited. These evil effects, arising from what is emphatically and properly called over-cropping, have, therefore, been established beyond doubt.

manure.

To obviate the serious evil of deterioration of soil and crop, which neither labour merely, however dexterous, nor manure, however well prepared, can prevent, the adoption of a succession of different kinds of crops has been attended with beneficial results. Thus a green crop, such as grass, turnips, or potatoes, was made to succeed a corn crop; and when this alternation of crops was substituted for a successive series of corn or grain-crops, experience soon discovered that less deterioration affected any crop of the series, or the land itself. It was also found, by this arrangement, that a longer period might elapse, than by the former, between the applications of manure, without diminishing the gross produce of the intermediate crops.

In the progress of experience, this beneficial arrangement of cropping was discovered not to bestow all the advantages of which the alternate system was capable. It was well to cause the gentler sway of the green crop to succeed the severer energies of a corn one; but it left the important question undecided, whether the particu lar corn crop selected was the most proper one by nature to follow its predecessor. Thus, it would be an improvement on the old series of cropping, to make wheat follow grass, barley after potatoes, and oats succeed turnips; but is wheat the best successor to grass of any of the corn crops? and, in like manner, a similar question might be asked of the rest of the series. Experience again suggested, that a better arrangement might be followed. It said, let wheat follow a bare fallow, potatoes, or beans; let barley succeed the turnip, and let oats be taken after the grass.

The trials of experience suggested yet better arrangements, to secure the greatest produce of the different kinds of crops. It was soon discovered that all kinds of soils were not adapted to the most luxuriant growth of all the kinds of crops. Thus a clay soil was found to suit wheat better than barley; a bare fallow better than turnips; and beans better than potatoes. A gravelly soil on the other hand, was most suited to those crops which were rejected by the clay soil.

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All these different changes and alterations suggested by experience, in the succession of crops, and the soils which are best suited to them, produce this irrevocable result that a particular corn crop shall succeed a particular green crop, on the soil that is best adapted to them; and that manure shall be applied, at given intervals, with one of the green crops, or with bare fallow. Thus, on strong soils, wheat must follow a manured fallow, grass after wheat, oats after the grass, then beans after oats, and wheat to precede the manured fallow after the beans. On weak soils, barley succeeds to turnips which have been manured, grass follows the barley, and oats precede the manured turnips.

Experience having proved that these successions of corn and green crops, on their respective soils, are best suited to insure the greatest produce, it is requisite that one series of successions shall follow another, in regular order, on its respective soil. These series of successions are called the "Rotation of crops." Should any alteration be desired in the rotation, it can only consist of a substitution of one corn crop for another, or one green crop for another; for the corn and green crops must always stand in the same relative position to each other. But this substitution of one crop for another will generally be attended with a sensible deterioration in the crop or soil, if the deterioration be not counteracted by an additional quantity of manure. A modification may be effected in the rotation by extending the time which it occupies. Thus the rotation on strong soils, which embraces six years, may be extended to seven or eight; and that of four years, on weak soils, may be extended to five or six years. The extension of the length of the rotation must be effected alone through the gentle, or the green, and not the severe or corn class of crops; and that not by means of any of the green crops indiscriminately. Thus the extension must not be effected by a repetition of any of the corn crops; for, we have already observed, such a proceeding would hasten their own deterioration; nor by adding an alternate green and corn crop to the end of the rotation, for that would be a mere attempt to deteriorate the soil by delaying the application of manure; nor by repeating the turnip or potatoe crop, for neither can be raised without manure ;-but it must be effected by allowing the grass to remain as many years longer as it is desired to extend the term of the rotation. The period of grass crop can alone be extended without trouble.

Experience again steps forward to check speculation in the endurance of the grass crop. On strong soils it is inimical to the grass crop to prolong its existence beyond one year, and hence annual grasses and the six years' rotation is best suited to that class of soils; whereas, an extension of the existence of grass on the weaker soils, serves to strengthen the energy of the soil. Two at least, or perhaps three years of grass confers a lasting benefit on such soils. Having thus fixed upon the length of rotation which is best adapted to the soil, let it be irrevocably adhered to.

In the establishing of this beneficial system of cropping, experience alone has discovered the progressive steps which have led to its completion. The rationale of the system has never been inquired into by those who have administered its rules or benefited by their application. The investigation of causes is the duty of the philosopher, and not of the farmer, who has only to deal with effects; but the happiest results may be anticipated from the combined efforts of both; when the former directs his mind to establish the principles upon which the experienced operations of the latter depend.

Among all the important practices in husbandry, that of the rotation of crops is the most important; for by an attentive adherence to it, the utmost regularity of

work will be maintained through every department of labour. To a steady adherence to this practice is justly ascribed all the improvements on land which have attracted the admiration of every lover of this country: to it is properly attributed the regular apportionment of an invariable extent of land, which is annually devoted to the growth of culmiferous crops; and which regularly checks, as far as human means can, injurious fluctuation in the supply of the first necessary of life : and to it is accurately imputed the supply of the immense numbers of high-fed live-stock which daily grace our markets.

To the intelligent agriculturist it is delightful to learn that the discoveries of science tend more and more to develop those principles which his practice illustrates. That practice has hitherto kept "the even tenor of its way," by the guidance of unerring experience, amid the contempt of scientific reproach. It now receives its justification in the confession of scientific error.

Various reasonings have hitherto been employed by men of science to account for the necessity of a rotation of crops. It has been thought sufficient to explain all the phenomena to state, that different plants absorb different juices from the same soil, and, therefore, though the ground may be exhausted by one class of vegetables, it may be rich enough for another. But it is well known to botanical physiologists, that plants absorb all the soluble substances which the soil contains, whether injurious to their growth or not. It has also been stated as an explanation, that the roots of different plants, being of different lengths, extend into dif ferent layers of the soil, and thus derive from it adequate nourishment. But the roots of all plants must be in the same stratum at the period of germination, and it is besides probable that all the arable part of the soil is homogeneous. It is known that plants of the same family, such as clover and lucerne, do not prosper in succession, although their roots are of different lengths. These theories are therefore not satisfactory.

BRUGMANS stated that a portion of the juices which are absorbed by the roots of plants, are, after the salutiferous portions have been extracted by the vessels of the plant, again thrown out by exudation from the roots, and deposited in the soil. This idea has been more fully pursued by DE CANDOLLE, who sees in it the true theory of the rotation of crops. He thinks it probable, that it is the existence of this exuded matter, which may be regarded in some measure as the excrement of the preceding crop of vegetables, that proves injurious to a succeeding vegetation. He has compared it to an attempt to feed animals upon their excrements. The particles which have been deleterious to one tribe of plants, cannot but prove injurious to plants of the same kind, and probably to those of some other species, while they furnish nutriment to another order of vegetables. Hence why one kind of corn crop is insured by immediately succeeding another of the same kind; hence why different kinds of crop may with advantage succeed one another; hence in short, the propriety of a rotation of crops.

To subject these theoretic views to the test of experiment, M. I. MACAIRE has made many experiments to prove that vegetables exude matter from the roots, and which are related by him in a memoir inserted in the Transactions of the Société de Physique et d'Histoire Naturelle of Geneva*. After various attempts to raise plants in pure siliceous sand, pounded glass, washed sponge, white linen, he decided upon pure rain-water. After cleansing and washing the roots thoroughly, he placed them in vials with a certain quantity of pure water. After they had put forth leaves, expanded their flowers, and flourished for some time, he ascertained, by the evaporation of the water, and the use of chemical re-agents, that the water * See Edinburgh New Philosophical Journal, No. xxviii. p. 215.

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