Page:The New International Encyclopædia 1st ed. v. 12.djvu/822

* MALAPROP. 730 a[AI.ARIA. also euiployed by Shakespeare in tlic character of Dogberry (Much Ado About Nothing, 1600). MALAP'TEBU'RUS (NeoLat. for *mala- coptcrurus, from Gk. /ja'/MHOc, vialuKus, soft + VTei>6v, ptcroii, wing, fin + ovpi. oura, tail). A genus of African catfish (q.v.), in which in place of a free dorsal fin there is a soft fatty tin near the tail. Two species are known, viz., Malapte- rurus eleclricus and Malaplvrurus Bcninensis, both remarkable principally for their electric or- gans and i)rojM?rties. See "Klectkic Fishes. MALAR, ma'lar, or MAELAR. One of the largest and most heaulil'ul lakes in Sweden, stretcliing for seveiily miles westward from Stockholm, with a breadth of from 2 to 23 miles (Map: Sweden, G 7). Its waters are nearly on a level willi the Baltic Sea, into which they are discliarged by channels running through and around the city of Stockholm. The lake contains over 1200 islands, and the scenery along its shores is niudi varied with wood, law'n, and cliffs, and adorned with castles, country-seats, and villas. The surrounding country is fertile and populous, and upon the shores stand the towns of Enkiiping, Vosteras. Strongniis, and a number of villages. MALARIA (from It. maV aria, bad air, from mala, feni. sg. of mato. from Lat. mains, bad, and aria, from Lat. aer, from Gk. a-^p, air, from itip, aein, to blow), and Malarial Fever. This disease was until recent years regarded as a poisonous emanation (whence the name) from the soil of certain localities, but is now definitely linown to be one of the specific infectious dis- eases, and to be caused by an animal parasite peculiar to the blood of man and mosquitoes — the J'lasmodiiim malariw. This parasite, discovered in 1880 by Laveran (q.v.) belongs to a class of protozoa called hemocytozoa or hemosporidia which attack and develop in the red blood cor- puscles of animals, birds, and fish, and of which numerous species are known. In the human blood several varieties of the parasite have lieen dis- tinguished, each associated with a definite type of fever. These are the parasites of tertian, quar- tan, and sestivo-autunmal fever. It was first pointed out by Golgi that the tertian and quar- tan parasites c.vist in the blood in great groups, all the meml)ers of which are at approximately the same stage of devehipment. An entire group, for example, undergoes sporulation within a few hours' time, and this sporulation is always ac- companied by the malarial paroxysm. The ter- tian parasite requires about forty-eight hours to accomplish its life cycle and produce spores; the quartan about seventy-two hours; so that in a single infection with one or the other of these parasites we observe the characteristic malarial paroxysm on every third and every fourth day, respectively. Double infection, that is. the in- troduction of two separate groups of parasites at different times, may occur, however, and produce daily paroxysms or attacks on two successive days, with a day's intermission, etc. The exact duration of the life cycle of the a-stivo-aiitumnal type of parasite is less definitely understood. Sporulation may occur at irregular intervals, or may take place continuously, and the resulting fever is correspondingly irregular and sometimes almost continuous. The Plasmodium may be observed in the blood of individuals suffering from an attack of malarial fever, moving about in the plasma or attacking and destroying the red blood corpuscles. It begins its life cycle as a small round or oval hyaline amoeboid body. The tertian variety is the largest, and is about the size of a red corpuscle (jj'j^ of an inch in diameter). The a-stivo-autumnal variety is less than half that size, the quartan somewhere be tween the two. The red corpuscles attacked become expanded or shrunken, and decolorized, and the pigment collects in clumps of granulr-.. Later on, long, active processes called flagethr develop from the full-grown parasite, and movr about freely in the blood. These are believed t^ be the sexual elements. The most brilliant chapter in the history of malaria investigation records the series of ex- periments by Koss. Manson, and others which proved that the disease was not air-borne, but communicated exclusively by the bites of mos quitoes which serve as intermediary hosts fur the parasite, and are the sole agents of infection Only a particular family of mosquitoes — tlic anopheles — are capable of coninumicating the dis ease. Of these three species have Ijecn recognized in this country. The Anopheles t]uadriniacula/iis is most concerned in the spread of malaria in tliu L'nited States, and is probably identical willi Anopheles claviger, the most active agent in Europe. Until the truth of the mosquito theory was established, the only protection again-t malaria was quinine. Now. how'cver, a mui h more eti'eetive defense is possible for those com pelled to live in malarious districts. This con sists in shielding themselves from the bites ' t mosquitoes, especially at night, by the use of net- and screens: in waging a constant warfare upon the insects by draining stagnant pools and marshes where they breed; and in destroy in;: their larvae by the liberal use of petroleum dur- ing the malarial season. See Insects, I'koi'aua- Tiox oi' Disease by. Malaria has a wide geographical distribution. No continent is entirely free from it, and certain parts of the tropics are practiciflly uninhabitable by reason of the severe types of fever which pre- vail. In Africa the west coast is the worst dis- trict. In Asia many portions of India, especially along the valleys of the Ganges and Indus rivers, and parts of China and Persia, are malarious. In Europe the disease prevails in Holland, North Germany, the west coast of Italy, and the far districts of England. In North America it occurs chiefly along the lower Atlantic seaeoast and in the Gulf States. The disease is always associated with warm, marshy soils, estuaries, badly drained low-lying districts, and tracts of land rich in vegetation, which offer suitable breeding places for the mosquito. A typical attack of malaria, or paroxysm, is characterized by three well-defined stages — the eold stage is preceded by a headache, yawning, and general malaise; gradually the patient begins to shiver, and in the height of the chill shakes violently. The temperature rises to 102 or even to 10.5 or 106 degrees. This stage lasts from ten minutes to an hour, and is followed by the hot stage, during which the coldness of the surface disappears and the skin becomes flushed. In from one-half to three or four hours the sweat- ing stage sets in. Beads of perspiration appear on the forehead, and the whole body is bathed in a copious sweat. The fever and headache dis- appear, and within an hour or two the patient