The Gulf Stream is a well-known oceanic current, so called because it issues from the Gulf of Mexico. It owes its origin to the fact that the westward moving waters of the tropical portion of the Atlantic Ocean, encountering the eastward projection of South America, become divided into two currents, one setting southwards along the Brazilian coast, and the other northward past the mouths of the Amazon and Orinoco, into the Caribbean Sea. It then enters the Gulf of Mexico, and thence emerges through the Channel of Florida as the Gulf Stream. Its course is next to the north and eastwards, in a direction parallel to the coast of the United States, past Cape Hatteras, along the southern edge of the 'great banks' of Nantucket and Newfoundland (between the meridians of 48 and 60 degrees west), after which its course as a distinct current is less obvious.
In the earlier part of its course, especially when rounding the extremity of Florida, the Gulf Stream forms a well-defined current, distinguished by its high temperature and its deep blue or indigo colour. On account of the descent of the Polar or Baffin Bay current along the coast in a direction opposite to that of the Gulf Stream, the water on its inland side is colder than that to the eastward of it. The difference of temperature between the Gulf Stream and this cold current sometimes amounts to 20 or even 30 degrees Fahrenheit
The velocity of the Gulf Stream varies with its course. Within the Florida Channel it attains a mean of 65 miles per day, this sinks to 56 miles off Charleston, becomes 36 miles to 46 off Nautucket, and 28 miles to the south of the Newfoundland Banks; 300 miles to the eastward of Newfoundland its movement is hardly perceptible. At the bottom of the Florida Channel the observed temperature is 34 degrees that of the surface from 80 to 84 degrees Fahrenheit. Research Gulf Stream
A plain is an expanse of low and nearly level land. Some plains, such as the Fens of England, large parts of Holland, and extensive areas of Russia, are almost perfectly flat; but generally an extensive plain consists of wide, gently sloping valleys separated by low hills. Such a plain is termed ' rolling' or 'undulating'. Many plains look extremely flat when viewed from the top of the neighbouring hills, but on descending one finds numerous instances of steep gradients, the valley slopes of the streams which cross the plain.
Plains are not all of the same type. Some plains may have been formed by the wearing down of lands that were once much higher. Such areas are more correctly called 'peneplains', e.g. Finland, a lowland area of very old rock, the HudsonBaylowlands, and Anglesey. Secondly, where layers of rock have not been folded but remain almost horizontal, extensive plains also occur. The Central Plains of the United States and the great plains of European Russia are in this group. Thirdly, plains may have been formed by the gradual accumulation of silt brought down by rivers. These are usually called alluvial plains. Good examples are the plain of North China, the Indo-Gangetic plain, the plains of Iraq, and much of the Amazonlowland. Some plains are the beds of old lakes. Rivers entering a lake deposit silt which is spread by the movement of the water over the lake floor. Such plains, though not large in size, are usually very fertile. Much of the great wheat land of Southern Manitoba is the bed of an old lake -lake Agassiz. The fertile plains of Hungary are of similar origin. Finally, some plains, such as the coastal plains of the United States from ChesapeakeBay to Florida, have been formed by the uplift of part of the sea floor bordering a continent.
The plains of the world tend to be areas of most advanced development and densest settlement. They are easier to cultivate than highland areas as the soil is usually deeper and more fertile. Hence the great plains, except where covered with large tracts of uncleared forest or occasional deposits of infertile soil, are important agricultural lands. Some plains, such as portions of Central Asia or of the Murray-Darling Basin, are too dry for successful agriculture. Unless irrigation is a practical possibility such plains are occupied by pastoral farmers engaged in rearing animals, and even the pastoral farmers sometimes have to bore wells for water, as in Hungary and in Australia. Where coal is found in or near plains, densely populated industrial centres usually develop, as in the North-Central United States. Movement is easy in all directions over lowlands, and rivers are generally slow and easily navigable, so that they are used as commercial highways. This is well illustrated by the United States, where the Mississippi and its tributaries provided the main lines of communication before the period when railways were developed.
The acouchi is a cavy-like rodent of the genus Myoprocta, family Dasyproctidae. They are found in the Amazon forests where they eat plants. Research Acouchi
The Amazon Ant (Formicidae rufescens) is a reddish coloured ant, about eight millimetres long found in a large part of the temperate Holarctic region preferring sunny, warm habitats on sandy soil or limestone. Amazon ants have aggressive sword-like mandibles which they use as weapons when raiding. The Amazon ant is remarkable in that it is unable to build a nest, feed itself or rear its offspring. Instead it raids other ant nests, particularly those of Formica fusca, and carries off pupae which soon hatch and are employed as slaves. Amazon ant raids usually occur in late afternoon in July and August. The Amazon ants emerge, and after a while slowly line up into a formation a few centimetres wide and several metres long containing thousands of ants. This formation then marches the tens of metres to another antnest, kill the defending ants and carry away thousands of pupae to be hatched as slave workers. After mating, the winged male dies, but the winged female sheds her wings and assaults an antnest of another species, penetrating the nest she kills the queen ant and gradually takes over the entirenest, enslaving the worker ants. Research Amazon Ant
Ant is the popular name for hymenopterous (or membranous-winged) insects of various genera of the super-family Formicoidea. Ants are found in most temperate and tropical regions. They are small but powerful insects, and have long been noted for their remarkable intelligence and interesting habits. They live in communities regulated by definite laws, each member of the society bearing a well-defined and separate part in the work of the colony. Each community consists of males; of females much larger than the males; and of barren females, otherwise called neuters, workers, or nurses. The neuters are wingless, and the males and females only acquire wings for their Nuptial flight, after which the males perish, and the few females which escape the pursuit of their numerous enemies divest themselves of their wings, and either return to established nests, or become the foundresses of new colonies. The neuters perform all the labours of the ant-hill or abode of the community; they excavate the galleries, procure food, and feed the larvae or young ants, which are destitute of organs of motion. In fine weather they carefully convey them to the surface for the benefit of the sun's heat, and as attentively carry them to a place of safety either when bad weather is threatened or the ant-hill is disturbed. In like manner they watch over the safety of the nymphs or pupae about to acquire their perfect growth. Some communities possess a special type of neuters, known as 'soldiers,' from the duties that specially fall upon them, and from their powerful biting jaws.
There is a very considerable variety in the materials, size, and form of ant-hills, or nests, according to the peculiar nature or instinct of the species. Most of the British ants form nests in woods, fields, or gardens, their abodes being generally in the form of small mounds rising above the surface of the ground and containing numerous galleries and apartments. Some excavate nests in old tree-trunks. One little yellow ant (Myrmica domestica) is common in houses in Britain in some localities. Some ants live on animal food, very quickly picking quite clean the skeleton of any dead animal they may light on. Others live on saccharine matter, being very fond of the sweet substance, called honey-dew, which exudes from the bodies of Aphides, or plant-lice. These they sometimes keep in their nests, and sometimes tend on the plants where they feed; sometimes they even superintend their breeding. By stroking the aphides with their antennae they cause them to emit the sweet fluid, which the ants then greedily sip up. Various other insects are looked after by ants in a similar manner, or are found in their nests. It has been observed that some species, like the European Red Ant (Formica sanguinea), resort to violence to obtain working ants of other species for their own use, plundering the nests of suitable kinds of their larvae and pupae,which they carry off to their own nests to be carefully reared and kept as slaves. Amazon Ants (Polyergus rufescens) often keep between three and five times as many slaves as their own inhabitants in a nest.
In temperate countries male and female ants survive, at most, until autumn, or to the commencement of cool weather, though a very large proportion of them cease to exist long previous to that time. The neuters pass the winter in a state of torpor, and of course require no food. The only time when they require food is during the season of activity, when they have a vast number of young to feed. Some ants of southern Europefeed on grain, and store it up in their nests for use when required. Some species have stings as weapons, others only their powerful mandibles, or an acrid and pungent fluid (formic acid) which they can emit. The name ant is also given to the neuropterous insects otherwise called Termites.
In the 1990's a new species of ant, in appearance the same as any common garden ant, was discovered in Budapest and in 2009 the same species was found in Britain, which has a suicidal attraction to electrical fields - an attraction which overides even the desire to eat. Like American fire-ants, these ants are drawn in vast quantities to electrical switches where they die and can cause failure of the electrical system due to the numbers of ants involved, typically hundreds of thousands. In Texas, fire-ants are a major cause of traffic light failures, being drawn to the switch boxes where they die and short out the circuits. Research Ant
Bertholletia is the name given in honour of Berthollet to a genus of Myrtacese, of which only one species, Bertholletia excelsa, is known. This tree forms vast forests on the banks of the Amazon, Rio Negro, and Orinoco, averaging 30 metres in height, with a stem only 60 cm in diameter, and destitute of branches until near the top. It produces the well-known Brazil-nuts of commerce, which are contained in a round and strong seed-vessel, to the number of from fifteen to fifty or more, and contain a great deal of oil. Research Bertholletia
The Bussu-palm (Manicaria saccifera) is a South American palm found in the swamps of the Amazon, whose stem is only three to four meters, but whose leaves are often nine metres by one and a half metres in breadth. These are used by the Indians for thatch, the spathes are used as bags, or when cut longitudinally and stretched out they form a coarse but strong kind of cloth. Research Bussu-Palm
Cayman or Caiman is the name given to several species of tropical American alligators, differing from typical alligators in certain minor details of structure. They are most numerous on the banks of the Amazon where they are known as jacare or yacare. Research Cayman
The Dipnoi are an order of fishes, including only the singular mud-fishes (Lepidosiren), important as exhibiting the transition, between fishes and the amphibia. Formerly Lepidosiren was reckoned the lowest of the amphibia, now it constitutes the highest order of fishes. The body is fish-like in shape, covered with small horny scales of a cycloid character; the pectoral and ventral fins are represented by two pairs of long filiform organs; the heart has two auricles and one ventricle, and the respiratory organs are twofold, consisting of ordinary gills opening externally, and of true lungs - formed by the modified swimming-bladder - communicating with the oesophagus by means of an air-duct or trachea, whence the name. They are also called Protopteri. The combination of respiratory organs is similar to that which is presented by the tailed amphibians with persistent gills (perennibranchiate), as the axolotl. This interesting group is allied to the ganoids through the Ceratodus of Queensland. The Lepidosiren paradoxa is found in the Amazon; Lepidosiren annectens in the Gambia. Research Dipnoi
The hoatzin (Opisthocomus cristatus) is a curious bird found only in the dense undergrowth which fringes the margins of rivers and lagoons around the Amazon. It is pheasant-like, with a long, thin body, a strong, serrated beak, an erectile crest on the head and long claws. The breast-bone is curiously modified, the keel being much reduced, having its anterior portion aborted and its posterior flattened out. Over this flattened region is a thickened patch of skin on which the bird rests. The crop is enormous, and the bird consumes large quantities of leaves and fruit. The young are remarkable in having claws both on the thumb and the index finger, and in using these, together with the bill and feet in scrambling about among the branches. Research Hoatzin
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Gulf Stream
