cabbage palm of the West Indies, and which is eaten either raw as a salad, or cooked. Further, the leaves afford so excellent a material for covering houses, that even in those hot and humid parts of the world, where decomposition goes on so rapidly, it does not require to be renewed oftener than once in seven years.

The Mauritia flexuosa, or fan palm of the Oronooco, is of still greater utility to the natives of South America. It is a social palm, abounding in the marshes, and having a geographical range of very vast extent. The whole northern portion of South America, east of the Cordilleras, appears to be possessed of this gorgeous palm; from the mouth of the Oronooco to the river Amazon, and through the whole of Guiana, through Surinam and the northern part of Brazil, and in very various places along the river Amazon, even to its source on the eastern declivity of the Cordilleras, this palm is found, constituting forests of greater or less extent. Its smooth grey stem rising often 100 feet, forms groups that, in the northern part of Brazil, resemble the pallisades of some gigantic fortress. The produce of these lofty cylinders is very great, not merely of sago, which is procured only when the process of flowering is about to occur, but many trees being cut down before this event, a juice is obtained from them, which forms, by fermentation, a sweet wine; while those that flower, after which no good sago can be got, furnish an extraordinary quantity of fruit, hanging in bunches many feet in length, which is as agreeable as ripe apples, the taste of which it resembles. The other products of this tree are numerous[J].

It would lead beyond just limits, were we to notice in detail, the plants which yield starch suitable for food, only after undergoing a process of art, by which an acrid principle is driven off, and a bland, wholesome substance remains behind. Such is the Janipha (or Jatropha) Manihot, which yields the Mandiocca, Tapioca, or Cassava, an article not only of great consumption in, but also of considerable export from, Brazil (see Spix and Martius’ Travels, and Lib. of Enter. Knowledge, Vegt. Sub. Food of Man, p. 152), which, when raw, is poisonous both to man and cattle, though it becomes safe and agreeable by the application of heat. So likewise the large tubers of several Arums, such as A. Macrorhizon, A. Colocasia, Caladium acre, and which are cultivated with great care in tropical and subtropical countries, particularly in the Sandwich and South Sea islands. All of these excite inflammation and swelling of the mouth and tongue, even to the danger of suffocation, but which are disarmed of their virulence, and converted into an article of daily consumption, by fire. Even yams and sweet potatoes, which are naturally mild, are less articles of consumption in the south sea islands, than the Tarro, as these tubers of the arums are designated.

I omit all other plants to fix attention on the potatoe, which is not only the source of the purest starch of all, but has many interesting points connected with its history and habitudes, peculiarly connected with my subject. No plant has contributed more to banish those famines which were formerly of so frequent occurrence in Europe, and all the dire train of suffering and disease consequent upon them. Yet did it, in many instances, require royal edicts to induce some nations to cultivate what is now regarded as one of the prime blessings of Providence, from nearly one end of the earth to the other; the potatoe being raised from Hammerfest, in Lapland, lat. 71° north, through all Europe, the plains of India, in China, Japan, the south-sea islands, New Holland, even to New Zealand. What renders it so peculiarly valuable is, that in the seasons when the corn crop fails, that of potatoes is generally more abundant; thus furnishing a substitute for the other, which proves defective from atmospheric conditions, which have little influence over the potatoe, placed as it is underground, and secure against extremes of temperature. The potatoe is not a root, as commonly supposed, but an underground collection of buds, having a quantity of starch accumulated around them, for their nourishment when they begin to grow. The quantity of starch varies greatly with the kind of potatoe cultivated, the mode of cultivation, the time of setting, and above all, with the season of the year when the analysis is made. Potatoes in general, afford from one-fifth to one-seventh their weight of dry starch[K]; besides some other nutritive materials. The quantity of starch seems to be at its maximum in the winter months; as 100 pounds of potatoes yield in August about 10 lbs., in October nearly 15 lbs., in November to March 17 lbs., in April 13¾ lbs., and in May 10 lbs. Nor is the quantity of starch alone diminished in spring, but the nitrogen which belongs to some of the other nutritive principles, likewise suffers a deduction; as fresh, not dried potatoes, contain 0.0037 per cent. of azote, while potatoes ten months old contain only 0.0028, causing a sensible difference in their power of imparting nourishment. The starch is withdrawn from the tubers of the potatoe, precisely in the same way that it is transferred from the root, stem, or seeds of other plants, for the service of the young shoot; but the mode in which it is accomplished is but of recent discovery, and constitutes one of the most beautiful instances of design which the whole vegetable kingdom can unfold; “that man’s scepticism must be incurable who does not perceive, and acknowledge, that the means now to be detailed were created for the express accomplishment of the ends[L].”

Starch has been described above as consisting of a multitude of little cells or vesicles, having an envelope, insoluble in water, formed of a kind of organized membrane, and containing within it a substance which is soluble in water, termed amidin. This soluble material is the nutritive element on which the young shoot, proceeding from every eye or bud of the potatoes, is to subsist, till it has developed roots, and unfolded its leaves to prepare additional alimentary substance. But if this soluble material be enclosed in an insoluble membrane, how are the contents to be made available for the growth of the plant? It is true, indeed, that water of the temperature of 160° Fahr. can rupture this tegument, as occurs in the process of boiling potatoes; but the water diffused through the earth in the neighbourhood of the growing tuber, never reaches such a height. How then is the difficulty obviated? This is effected by a secretion called diastase which is found in the tubers in the immediate vicinity of the eyes or buds. “It is stored up in that situation for the purpose of being conveyed, by the vessels connected with the bud, into the substance of the tuber, when the demand for nutrition is occasioned by the development of the shoot. It is probable that the secretion of diastase takes place in every instance in which starch previously deposited is to be re-absorbed[M].” It is not to be found before grains or tubers begin to sprout, yet, “such is its energy, that one part of it is sufficient to render soluble the interior portion of two thousand parts of starch, and to convert it into