Personal Narrative of Travels to the Equinoctial Regions of America, During the Years 1799-1804, Vol.2 — Chapter 2.16, Part 6

In examining the physical properties of animal and vegetable products, science displays them as closely linked together; but it strips them of what is marvellous, and perhaps, therefore, of a part of their charms.

Nothing appears isolated; the chemical principles that were believed to be peculiar to animals are found in plants; a common chain links together all organic nature.

Long before chemists had recognized small portions of wax in the pollen of flowers, the varnish of leaves, and the whitish dust of our plums and grapes, the inhabitants of the Andes of Quindiu made tapers with the thick layer of wax that covers the trunk of a palm-tree.

* (* Coroxylon andicola.

) It is but a few years since we discovered, in Europe, caseum, the basis of cheese, in the emulsion of almonds; yet for ages past, in the mountains of the coast of Venezuela, the milk of a tree, and the cheese separated from that vegetable milk, have been considered as a salutary aliment.

How are we to account for this singular course in the development of knowledge?

How have the unlearned inhabitants of one hemisphere become cognizant of a fact which, in the other, so long escaped the sagacity of the scientific?

It is because a small number of elements and principles differently combined are spread through several families of plants; it is because the genera and species of these natural families are not equally distributed in the torrid, the frigid, and the temperate zones; it is that tribes, excited by want, and deriving almost all their subsistence from the vegetable kingdom, discover nutritive principles, farinaceous and alimentary substances, wherever nature has deposited them in the sap, the bark, the roots, or the fruits of vegetables.

That amylaceous fecula which the seeds of the cereal plants furnish in all its purity, is found united with an acrid and sometimes even poisonous juice, in the roots of the arums, the Tacca pinnatifida, and the Jatropha manihot.

The savage of America, like the savage of the South Sea islands, has learned to dulcify the fecula, by pressing and separating it from its juice.

In the milk of plants, and in the milky emulsions, matter extremely nourishing, albumen, caseum, and sugar, are found mixed with caoutchouc and with deleterious and caustic principles, such as morphine and hydrocyanic acid.

* (* Opium contains morphine, caoutchouc, etc. ) These mixtures vary not only in the different families, but also in the species which belong to the same genus.

Sometimes it is morphine or the narcotic principle, that characterises the vegetable milk, as in some papaverous plants;

sometimes it is caoutchouc, as in the hevea and the castilloa;

sometimes albumen and caseum, as in the cow-tree.

The lactescent plants belong chiefly to the three families of the euphorbiaceae, the urticeae, and the apocineae.

* (* After these three great families follow the papaveraceae, the chicoraceae, the lobeliaceae, the campanulaceae, the sapoteae, and the cucurbitaceae.

The hydrocyanic acid is peculiar to the group of rosaceo-amygdalaceae.

In the monocotyledonous plants there is no milky juice; but the perisperm of the palms, which yields such sweet and agreeable milky emulsions, contains, no doubt, caseum.

Of what nature is the milk of mushrooms?

) Since, on examining the distribution of vegetable forms over the globe, we find that those three families are more numerous in species in the low regions of the tropics, we must thence conclude, that a very elevated temperature contributes to the elaboration of the milky juices, to the formation of caoutchouc, albumen, and caseous matter.

The sap of the palo de vaca furnishes unquestionably the most striking example of a vegetable milk in which the acrid and deleterious principle is not united with albumen, caseum, and caoutchouc: the genera euphorbia and asclepias, however, though generally known for their caustic properties, already present us with a few species, the juice of which is sweet and harmless.

Such are the Tabayba dulce of the Canary Islands, which we have already mentioned,* (* Euphorbia balsamifera.

The milky juice of the Cactus mamillaris is equally sweet.

) and the Asclepias lactifera of Ceylon.

Burman relates that, in the latter country, when cow's milk is wanting, the milk of this asclepias is used; and that the ailments commonly prepared with animal milk are boiled with its leaves.

It may be possible, as Decandolle has well observed, that the natives employ only the juice that flows from the young plant, at a period when the acrid principle is not yet developed.

In fact, the first shoots of the apocyneous plants are eaten in several countries.

I have endeavoured by these comparisons to bring into consideration, under a more general point of view, the milky juices that circulate in vegetables; and the milky emulsions that the fruits of the amygdalaceous plants and palms yield.

I may be permitted to add the result of some experiments which I attempted to make on the juice of the Carica papaya during my stay in the valleys of Aragua, though I was then almost destitute of chemical tests.

The juice has been since examined by Vauquelin, and this celebrated chemist has very clearly recognized the albumen and caseous matter; he compares the milky sap to a substance strongly animalized--to the blood of animals; but his researches were confined to a fermented juice and a coagulum of a fetid smell, formed during the passage from the Mauritius to France.

He has expressed a wish that some traveller would examine the milk of the papaw-tree just as it flows from the stem or the fruit.

The younger the fruit of the carica, the more milk it yields: it is even found in the germen scarcely fecundated.

In proportion as the fruit ripens, the milk becomes less abundant, and more aqueous.

Less of that animal matter which is coagulable by acids and by the absorption of atmospheric oxygen, is found in it.

As the whole fruit is viscous,* (* The same viscosity is also remarked in the fresh milk of the palo de vaca.

It is no doubt occasioned by the caoutchouc, which is not yet separated, and which forms one mass with the albumen and the caseum, as the butter and the caseum in animal milk.

The juice of a euphorbiaceous plant (Sapium aucuparium), which also yields caoutchouc, is so glutinous that it is used to catch parrots.

) it might be supposed that, as it grows larger, the coagulable matter is deposed in the organs, and forms a part of the pulp, or the fleshy substance.

When nitric acid, diluted with four parts of water, is added drop by drop to the milk expressed from a very young fruit, a very extraordinary phenomenon appears.

At the centre of each drop a gelatinous pellicle is formed, divided by greyish streaks.

These streaks are simply the juice rendered more aqueous, owing to the contact of the acid having deprived it of the albumen.

At the same time, the centre of the pellicles becomes opaque, and of the colour of the yolk of an egg; they enlarge as if by the prolongation of divergent fibres.

The whole liquid assumes at first the appearance of an agate with milky clouds; and it seems as if organic membranes were forming under the eye of the observer.

When the coagulum extends to the whole mass, the yellow spots again disappear.

By agitation it becomes granulous like soft cheese.

* (* The substance which falls down in grumous and filamentous clots is not pure caoutchouc, but perhaps a mixture of this substance with caseum and albumen.

Acids precipitate the caoutchouc from the milky juice of the euphorbiums, fig-trees, and hevea; they precipitate the caseum from the milk of animals.

A white coagulum was formed in phials closely stopped, containing the milk of the hevea, and preserved among our collections, during our journey to the Orinoco.

It is perhaps the development of a vegetable acid which then furnishes oxygen to the albumen.

The formation of the coagulum of the hevea, or of real caoutchouc, is nevertheless much more rapid in contact with the air.

The absorption of atmospheric oxygen is not in the least necessary to the production of butter which exists already formed in the milk of animals; but I believe it cannot be doubted that, in the milk of plants, this absorption produces the pellicles of caoutchouc, of coagulated albumen, and of caseum, which are successively formed in vessels exposed to the open air.

) The yellow colour reappears on adding a few more drops of nitric acid.

The acid acts in this instance as the oxygen of the atmosphere at a temperature from 27 to 35 degrees; for the white coagulum grows yellow in two or three minutes, when exposed to the sun.

After a few hours the yellow colour turns to brown, no doubt because the carbon is set more free progressively as the hydrogen, with which it was combined, is burnt.

The coagulum formed by the acid becomes viscous, and acquires that smell of wax which I have observed in treating muscular flesh and mushrooms (morels) with nitric acid.

According to the fine experiments of Mr. Hatchett, the albumen may be supposed to pass partly to the state of gelatine.

The coagulum of the papaw-tree, when newly prepared, being thrown into water, softens, dissolves in part, and gives a yellowish tint to the fluid.

The milk, placed in contact with water only, forms also membranes.

In an instant a tremulous jelly is precipitated, resembling starch.

This phenomenon is particularly striking if the water employed be heated to 40 or 60 degrees.

The jelly condenses in proportion as more water is poured upon it.

It preserves a long time its whiteness, only growing yellow by the contact of a few drops of nitric acid.

Guided by the experiments of Fourcroy and Vauquelin on the juice of the hevea, I mixed a solution of carbonate of soda with the milk of the papaw.

No clot is formed, even when pure water is poured on a mixture of the milk with the alkaline solution.

The membranes appear only when, by adding an acid, the soda is neutralized, and the acid is in excess.

I made the coagulum formed by nitric acid, the juice of lemons, or hot water, likewise disappear by mixing it with carbonate of soda.

The sap again becomes milky and liquid, as in its primitive state; but this experiment succeeds only when the coagulum has been recently formed.

On comparing the milky juices of the papaw, the cow-tree, and the hevea, there appears a striking analogy between the juices which abound in caseous matter, and those in which caoutchouc prevails.

All the white and newly prepared caoutchouc, as well as the waterproof cloaks, manufactured in Spanish America by placing a layer of milk of hevea between two pieces of cloth, exhale an animal and nauseating smell.

This seems to indicate that the caoutchouc, in coagulating, carries with it the caseum, which is perhaps only an altered albumen.

The produce of the bread-fruit tree can no more be considered as bread than plantains before the state of maturity, or the tuberous and amylaceous roots of the cassava, the dioscorea, the Convolvulus batatas, and the potato.

The milk of the cow-tree contains, on the contrary, a caseous matter, like the milk of mammiferous animals.

Advancing to more general considerations, we may regard, with M. Gay-Lussac, the caoutchouc as the oily part--the butter of vegetable milk.

We find in the milk of plants caseum and caoutchouc; in the milk of animals, caseum and butter.

The proportions of the two albuminous and oily principles differ in the various species of animals and of lactescent plants.

In these last they are most frequently mixed with other substances hurtful as food; but of which the separation might perhaps be obtained by chemical processes.

A vegetable milk becomes nourishing when it is destitute of acrid and narcotic principles; and abounds less in caoutchouc than in caseous matter.

* (* The milk of the lactescent agarics has not been separately analysed; it contains an acrid principle in the Agaricus piperatus, and in other species it is sweet and harmless.

The experiments of MM.

Braconnot, Bouillon-Lagrange, and Vauquelin (Annales de Chimie, volume 46, volume 51, volume 79, volume 80, volume 85, have pointed out a great quantity of albumen in the substance of the Agaricus deliciosus, an edible mushroom.

It is this albumen contained in their juice which renders them so hard when boiled.

It has been proved that morels (Morchella esculenta) can be converted into sebaceous and adipocerous matter, capable of being used in the fabrication of soap.

(De Candolle, sur les Proprietes medicinales des Plantes.

) Saccharine matter has also been found in mushrooms by Gunther.

It is in the family of the fungi, more especially in the clavariae, phalli, helvetiae, the merulii, and the small gymnopae which display themselves in a few hours after a storm of rain, that organic nature produces with most rapidity the greatest variety of chemical principles--sugar, albumen, adipocire, acetate of potash, fat, ozmazome, the aromatic principles, etc. It would be interesting to examine, besides the milk of the lactescent fungi, those species which, when cut in pieces, change their colour on the contact of atmospheric air.

Though we have referred the palo de vaca to the family of the sapotas, we have nevertheless found in it a great resemblance to some plants of the urticeous kind, especially to the fig-tree, because of its terminal stipulae in the shape of a horn; and to the brosimum, on account of the structure of its fruit.

M.

Kunth would even have preferred this last classification; if the description of the fruit, made on the spot, and the nature of the milk, which is acrid in the urticeae, and sweet in the sapotas, did not seem to confirm our conjecture.

Bredemeyer saw, like us, the fruit, and not the flower of the cow tree.

He asserts that he observed [sometimes?

] two seeds, lying one against the other, as in the alligator pear-tree (Laurus persea).

Perhaps this botanist had the intention of expressing the same conformation of the nucleus that Swartz indicates in the description of the brosimum--"nucleus bilobus aut bipartibilis."

We have mentioned the places where this remarkable tree grows: it will be easy for botanical travellers to procure the flower of the palo de vaca and to remove the doubts which still remain, of the family to which it belongs.

) Whilst the palo de vaca manifests the immense fecundity and the bounty of nature in the torrid zone, it also reminds us of the numerous causes which favour in those fine climates the careless indolence of man.

Mungo Park has made known the butter-tree of Bambarra, which M. De Candolle suspects to be of the family of sapotas, as well as our milk-tree.

The plantain, the sago-tree, and the mauritia of the Orinoco, are as much bread-trees as the rema of the South Sea.

The fruits of the crescentia and the lecythis serve as vessels for containing food, while the spathes of the palms, and the bark of trees, furnish caps and garments without a seam.

The knots, or rather the interior cells of the trunks of bamboos, supply ladders, and facilitate in a thousand ways the construction of a hut, and the fabrication of chairs, beds, and other articles of furniture that compose the wealth of a savage household.

In the midst of this lavish vegetation, so varied in its productions, it requires very powerful motives to excite man to labour, to rouse him from his lethargy, and to unfold his intellectual faculties.

Cacao and cotton are cultivated at Barbula.

We there found, what is very rare in that country, two large cylindrical machines for separating the cotton from its seed; one put in motion by an hydraulic wheel, and the other by a wheel turned by mules.

The overseer of the farm, who had constructed these machines, was a native of Merida.

He was acquainted with the road that leads from Nueva Valencia, by the way of Guanare and Misagual, to Varinas; and thence by the ravine of Collejones, to the Paramo de Mucuchies and the mountains of Merida covered with eternal snows.

The notions he gave us of the time requisite for going from Valencia by Varinas to the Sierra Nevada, and thence by the port of Torunos, and the Rio Santo Domingo, to San Fernando de Apure, were of infinite value to us.

It can scarcely be imagined in Europe, how difficult it is to obtain accurate information in a country where the communications are so rare; and where distances are diminished or exaggerated according to the desire that may be felt to encourage the traveller, or to deter him from his purpose.

I had resolved to visit the eastern extremity of the Cordilleras of New Grenada, where they lose themselves in the paramos of Timotes and Niquitao.

I learned at Barbula, that this excursion would retard our arrival at the Orinoco thirty-five days.

This delay appeared to us so much the longer, as the rains were expected to begin sooner than usual.

We had the hope of examining afterwards a great number of mountains covered with perpetual snow, at Quito, Peru, and Mexico; and it appeared to me still more prudent to relinquish our project of visiting the mountains of Merida, since by so doing we might miss the real object of our journey, that of ascertaining by astronomical observations the point of communication between the Orinoco, the Rio Negro, and the river Amazon.

We returned in consequence from Barbula to Guacara, to take leave of the family of the Marquis del Toro, and pass three days more on the borders of the lake.

It was the carnival season, and all was gaiety.

The sports in which the people indulge, and which are called carnes tollendas,* assume occasionally somewhat of a savage character.

(* Or "farewell to flesh."

The word carnival has the same meaning, these sports being always held just before the commencement of Lent.

) Some led an ass loaded with water, and, where-ever they found a window open, inundated the apartment within by means of a pump.

Others carried bags filled with hairs of picapica;* (* Dolichos pruriens (cowage).

) and blew the hair, which causes a great irritation of the skin, into the faces of those who passed by.

From Guacara we returned to Nueva Valencia.

We found there a few French emigrants, the only ones we saw during five years passed in the Spanish colonies.

Notwithstanding the ties of blood which unite the royal families of France and Spain, even French priests were not permitted to take refuge in that part of the New World, where man with such facility finds food and shelter.

Beyond the Atlantic, the United States of America afford the only asylum to misfortune.

A government, strong because it is free, confiding because it is just, has nothing to fear in giving refuge to the proscribed.