"Mandioc, Mandioca, or Maniva, Jatropha manihot, L.—Euphorbiaceæ. A plant with wide-spreading branches, originally from Africa, cultivated in India and in America, from the Straits of Magellan to Florida. As food, it is to Brazil what wheat is to Europeans and North Americans. The root is large, tuberous, fleshy, white internally, and full of a white juice very acrid and very poisonous. The leaves are alternate, divided in three, five, or seven lanceolate lobes, deeply cut and pointed, rather sinuous edges, dark green on the upper side and glaucous on the under side. The male flowers are separated from the female, but both. exist on the same plant.

"The root of the mandioc is that part of the plant which is most important. Some roots attain a very considerable size, and weigh as much as fifteen kilos (thirty pounds). The root is almost entirely composed of starch, with the addition of a poisonous white juice. This poison, which is very subject to change, appears to be cyanhydric acid, or a substance easily turned into that acid. However, it is found easy to deprive the mandioc root of its acid poisonous quality, either by the action of heat, or by repeated washings. The root then becomes a healthy, as it is also a universal, food. It is used for the preparation of farinha de mandioca (mandioc flour), one of the most valuable articles of diet in use among the Brazilians. The following is the process employed for the production of farinha (pronounced farinya):—

"The root is well scraped with a knife, the paste is then reduced by a vertical wheel, and next pressed to deprive it of the poisonous juice. It is then roasted, which extracts the last remains of the poisonous principle, and gives it that look of granulated white flour which is seen at table. It is also called farinha de páo (wood flour, or sawdust).

"The water in which the paste of the mandioc has been washed is left to deposit at the bottom of the vessels a white silt which is very pure starch. This, when dried, is called tapioca, a very delicate and nutritious food.

"The juice of the root is a powerful poison. A small dose is fatal to men and animals after producing vomiting and convulsions. This poisonous principle of the mandioc is very volatile ; for if the juice be exposed to the air, it loses its deleterious effects after

thirty-six hours. The same result occurs when the juice is boiled. When distilled, it furnishes a most poisonous liquid; a few drops placed on the tongue of a dog are sufficient to kill him in ten minutes.

"The name manipuêra is given to the liquid resulting from squeezing the scraped root, which latter is placed in the tepiti (a kind of basket or vessel made of taqua russú, or split and plaited taqua.) Notwithstanding its being so poisonous, the juice is employed for preparing tucupi-a sauce much used in Pará, Amazonas, and Maranhão. To prepare it, the liquid is boiled with hot peppers and garlic, or else these ingredients are merely macerated, and then exposed to the air and night dews.

"When the tuber is macerated and placed in water till it begins to ferment, it loses its poisonous properties, and, after being washed in several waters, it is used to make cakes.

"The name mandioca is given to the root, and maniva generally to the plant, of which there are many species."

Black beans, the feijões (singular feijão) to which I refer repeatedly, is Phaseolus vulgaris. When stewed in toucinho (lard), they form, with farinha, the staple food of the inhabitants. Another favourite dish is the feijoada, a stew of meat and black beans, which is also freely covered with farinha and made into a kind of thick mess-most unpleasant to look at, but excellent. A feijoada is one of the standing dishes at all the meals of his Majesty the Emperor. When at Rio de Janeiro, I was told of a great dinner given at Paris on the occasion of a national fête by the Brazilian Minister to the Brazilian residents in that city. The dinner was to be au Brésilien. Dish after dish made its appearance, but no feijoada. The guests were annoyed, and the host sent for the

"Diccionario de Botanica Brasileira," de Joaquim de Almeida Pinto. Mr. H. W. Bates states ("The Naturalist on the Amazons," vol. i. p. 194. note) that "many useful vegetable products have been reclaimed, and it is to the credit of the Indians that they have discovered the use of the mandioc plant, which is highly poisonous in the raw state, and requires a long preparation to fit it for use. It is cultivated throughout the whole of Tropical America ... but only in the plains, not being seen, according to Humboldt, higher than from six hundred to eight hundred metres, at which elevation it grows on the Mexican Andes. I believe it is not known in what region the plant originated; it is not found wild in the Amazons valley."

cook.

He said no power on earth would induce him to send up such a disgusting dish!

There are, of course, hundreds of wild plants which are used as food, for medicine, for dyeing purposes, etc. Press of other work prevented my being able to work out this matter as I should like to have done, but I may mention indigo, Indigofera tinctoria; salsaparilha or sarsaparilla, Smilax sarsaparilla; and ipecacuanha, Cephalis ipecacuanha, also called zucaquenha or picahonha. name ipecacuanha is derived from the Indian ipé-caá-goéne, "the little plant which causes emeticism" (goéne); or from ipé-caácúnha, "the little plant of the woman" (cunha), being much used in feminine complaints (Captain Burton, vol. i. p. 164, note).

The

Erythroxylon. One species of this genus, the celebrated coca, which is now becoming medically famous in England, is extensively "used in Peru for its remarkable power of stimulating the nervous system, in which respect it quite resembles opium. The leaves are used with a small mixture of finely powdered chalk."*

Melastomaceæ are handsome trees, shrubs, or herbaceous plants; the leaves have five or three ribs ; the flowers are purple or yellow.

There are many plants and shrubs, producing excellent fruit, of which I am unable to give the names. One (found December 10, 1883) grows on a shrub about one foot high; it is called pitanga, and is a bright crimson fruit, very luscious, tasting like an egg-plum, and has a large bean-shaped kernel. Another good fruit, called cajú, is very curious. It is like a small yellow apple in shape, and, though rather astringent, tastes like an over-ripe American apple; its large bean-shaped seed grows outside, on the top of the fruit (Psidium sp.).

NOTES ON THE GEOLOGY OF THE DISTRICTS VISITED.+

As I had no opportunity of inspecting the limestone districts of the valley of the Rio Paraopéba, wherein occur, in the caves, the remains of men and of animals under similar circumstances to

* "The Vegetable Kingdom,” p. 381. John Lindley, 1853.

+ M. Liais's "Géologie du Brésil" has been frequently referred to, “Climats, Faune," etc., pp. 1-38.

our own limestone caves, and as I was unable to visit the metalliferous districts of Pitanguy, Ouro Preto, or São João del Rey, though these were all within a ride of a few hours, I shall confine my remarks to the gneissic formations and their decomposition.

Stratified gneiss forms the total mass of the soil in all elevated parts near Rio de Janeiro and over vast areas of the empire of Brazil, the vegetable earth resting immediately on the top of these strata. I observed the same strata at Bahia. Gardner found it in the province of Ceará, five hundred miles to the north of Bahia ; and "Humbolt describes the gneiss-granite over an immense area in Venezuela, and even Columbia." The mineral composition of gneiss-which is made up of quartz, felspar, and mica-is the same as the components of granite, the only difference is in the former's foliated texture, hence gneiss may be described as schistosegranite. The gneiss is always upheaved at a high angle, and though the base is felspathic, the different strata have important structural differences in composition; granite and hornblende are present in different localities, and modify very considerably the composition of the rocks. To enter into the lithological structure of this group of strata is beyond the scope of a brief article; I should have to describe porphyries, granite, syenite, diorite, pegmatite, eurite, quartzite, gneiss, mica schists, magnetic ironstone, garnets, murchisonite, kaolin (porcelain clay), and numerous other combinations. of quartz, felspar, mica (red, black, or yellow), hornblende, etc., with other metamorphosed sedimentary deposits.

The most salient characteristic of these gneisses is their condition of decomposition, which has been effected on an immense scale. Even the United States do not present such an intensity of remarkable phenomena as do the rocks of Brazil. It is not unusual to find the gneiss completely transformed into clays to a depth of over three hundred yards. The barrancadas or canyons, carved out by the rains, give the plainest evidence of this decomposition. The heavy rains, especially after long continuance of dry seasons, produce the most marvellous effect. As an instance, I may cite (Liais) the storms of March, 1859, when five inches and a half (fourteen centimetres) of rain fell at Rio de * "Geolog. Observ.," Chas. Darwin, p. 424.

Janeiro in two hours, and caused great erosions at the Morro do Castello and on a multitude of argillaceous hills on the Nichteroy side of the bay. One must have seen the torrents in the mountain regions to understand the powerful part which, in the course of centuries, these phenomena can exercise on the configuration of the soil. I have mentioned how the different divides I worked over (four within about twenty miles) are all about the same height (3200 feet), and how these hills abound in canyons, and are separated by steep valleys, hundreds of feet deep, and sometimes a mile or more in breadth. Many of the erosions have the testimony of ocular demonstration. The Visconde de Prados described to M. Liais how one erosion occurred some forty years ago near Barbecena. This crevasse was about seven acres and a half in area, six hundred yards long, fifty-five yards wide, and over thirty feet deep. Therefore, from four hundred thousand to five hundred thousand cubic yards were washed away from this hillside, and the earth excavated entirely disappeared, being carried away by the waters. As these canyons are often from one hundred to three hundred feet deep, they show the power of decomposition by atmospheric agents on the gneiss, and this is in active operation. to-day.

These phenomena explain the valleys of denudation; they reveal how watersheds have been changed so that the original tributaries of the Parahyba do Sul or Rio de la Plata may now flow to the Rio São Francisco; and they show how valleys may be formed much more rapidly than might be considered at first sight. It is important to bear in mind the varying resistance to decomposition of different strata. This is the reason of the irregular and picturesque features so abundant in the mountainranges, of which the Organs offer a remarkable example. The name "Organ Mountains" has been given from the supposed resemblance of its peaks to the pipes of an organ, especially when seen from Rio. In the account of my journey to Petropolis, I have mentioned the vertical walls of rock surrounding the huge, deep amphitheatre now clothed in virgin forest, which the railway scales triumphantly. The pyramids and masses of rock consist of the harder portions of the original strata, which have been thrust up, like the slates of the Longmynd, in Shropshire, at a