54 MALARIA which, from the nature of the subsoil, retain the moisture a short distance beneath the sur- face, though that may be dry and parched, are favorable to the production of malaria. The process of clearing a new country of its woods, and thus exposing the soil to the full action oi the sun, is commonly followed by the prevalence of fevers ; and the same evils often follow the ploughing up of meadow lands. It is not ne- cessary that the amount of the vegetable matter be great or its growth recent, since malarious diseases have often been caused by the drainage of ponds and lakes ; and the fevers that pre- vailed at Bourg-en-Bresse ceased on filling in the half wet ditches of the fortifications. The low grounds on the margin of lakes and the al- luvial lands bordering rivers in warm countries are always plagued with malaria. In India ground covered with low thick growths of brushwood or of weeds and grass, called jun- gles, are so well known to produce malarious fevers, that they are there termed jungle fevers ; even open woods in tropical climates are pro- ductive of malaria. The steeping of hemp and flax, and the decay of vegetable refuse, pota- toes, &e., in confined localities, as cellars or the hold of a vessel, have resulted in fever. The quantity of water required for the generation of malaria is not large, a marsh completely covered with water being innocuous ; it is only when the moisture is drying up under the in- fluence of the sun that it becomes pestilential. So in tropical climates disease prevails chiefly at the commencement and after the termina- tion of the rainy season, and is less prevalent while the earth is saturated. In some cases the quantity of vegetable matter concerned in the production of malaria must be exceedingly small. Dr. Ferguson, one of the medical offi- cers in the army of the duke of Wellington, says: "In Spain, during the month of May, 109, which was cold and wet, the army re- mained healthy ; but in June, which was re- markably hot and dry, marching through a sin- gularly dry, rocky country of considerable ele- vation, several of the regiments bivouacking in the hilly ravines which had lately been water- courses, a number of the men were seized with violent remittent fever (the first which had shown itself on the inarch) before they could move from the bivouac the next morning ; and tin* portion of the troops exclusively were affected with this disorder for some time. In this instance, the half dried ravine having been the stony bed of a torrent, in which soil never could be, the very existence of vegetables, and consequently of their humid decay and putre- wns impossible, and the stagnant pools of water still left among the rocks by the wa- tercourse were perfectly sweet. Yet this sit- uation proved as pestiferous as the bed of a ' < 'ii the Nature and History of Marsh loison," Edinburgh, 1821.) Here, however, otal absence of vegetable matter would be inVult to prove, and would be in contradic- tion with all other experience.Whatever may MALATESTA be the nature of malaria, it is most concentra- ted near the surface of the earth, and becomes weaker as we rise above it; it is also most active at night, probably from the influence of the sun in rarefying and producing currents in the atmosphere, and perhaps, too, because it has a peculiar affinity for the fogs that are then, apt to prevail. In malarious countries it is well known that exposure to the night air is apt to be followed by fever, and that those who sleep in the upper rooms of a house are safer than those who lodge on the ground floor. While as a general rule low and damp grounds are much more unhealthy thali the hills in their neighborhood, yet in numerous instances this rule does not hold good, or is even reversed. The experience of the British army in the East and West Indies is conclusive on this point. In many cases this can readily be explained by the effect of winds and currents of air carry- ing the malaria to the higher ground, which had been generated on the lower ; thus in Italy the malaria from the borders of Lake Agnano reaches the convent of the Camaldules, situ- ated on a high hill three miles distant. Con- nected with the propagation of malaria by cur- rents of air is the fact that woods sometimes act as a screen, protecting a place from the ma- laria which would otherwise be conveyed to it from some neighboring source ; in Italy fevers have frequently become prevalent on the cut- ting down of trees which have thus served as a shelter. It becomes an interesting question bow far malaria can be carried by winds. This has been very variously estimated ; probably three or four miles is the maximum. The ef- fects of malaria are by no means confined to the production of fevers and diseases of an in- termittent type, but it is only in warm climates and in certain unfavorable localities that its full effects upon the constitution are observed. In such places the growth is stunted, the complex- ion sallow, the limbs slender, the abdomen tu- mid, the hair lank and scant, and the teeth de- 'ective ; life is commonly extinguished before 40 years of age, and the population is only cept up by immigration from healthier locali- ties. Yet it is remarkable that when in such places persons live beyond their 40th year, they frequently recover some measure of health and attain to old age. MALATESTA, a family of Italy, many of whose members were rulers of Rimini and other cities of the Romagna, and which became affiliated with the house of Montefeltro and with the dukes of Urbino. The founder of the family was Count Carpegna la Penna de' Billi, who ived in the llth century, and who on ac- count of his violent disposition was called mala l <e*ta (" bad head "), whence the surname of us descendants. Among the latter was Mala-
- esta, count of Verrncchio, who distinguished
himself against the Ghibellines, became ruler of Rimini in 1295, and died in 1312. He was succeeded by his son Malatestino, a zealous en- my of the Ghibellines, who in 1314 added Ce-
