TREES AS A PROTECTION AGAINST MALARIA. 1H 
haps it does not come strictly within the sphere of the present 
inguiry, but its importance will justify me in devoting some space 
to the subject. “It has been observed” (I quote from Bec- 
querel) “that humid air, charged with miasmata, is deprived 
of them in passing through the forest. Rigaud de Lille ob- 
served localities in Italy where the interposition of a screen of 
trees preserved everything beyond it, while the unprotected 
grounds were subject to fevers.” * Few European countries 
present better opportunities for observation on this point than 
Italy, because in that kingdom the localities exposed to mias- 
matic exhalations are numerous, and belts of trees, if not for- 
ests, are of so frequent occurrence that their efticacy in this 
respect can be easily tested. The belief that rows of trees 
afford an important protection against malarious influences is 
very general among Italians best qualified by intelligence and 
professional experience to judge upon the subject. The com- 
missioners, appointed to report on the measures to be adopted 
for the improvement of the Tuscan Maremme, advised the 
planting of three or four rows of poplars, Populus alba, in such 
directions as to obstruct the currents of air from malarious lo- 
ealities, and thus intercept a great proportion of the pernicious 
exhalations.” + Maury believed that a few rows of sunflowers, 
planted between the Washington Observatory and the marshy 
banks of the Potomac, had saved the inmates of that establish- 
ment from the intermittent fevers to which they had been for- 
merly liable. Maury’s experiments have been repeated in 
Italy. Large plantations of sunflowers have been made upon 
the alluvial deposits of the Oglio, above its entrance into the 
Lake of Iseo, near Pisogne, and it is said with favorable results 
to the health of the neighborhood.t In fact, the generally 
beneficial effects of a forest wall or other vegetable screen, as 
a protection against noxious exhalations from marshes or other 
* BECQUEREL, Des Climats, etc., p. 9. 
¢ SALVAGNOLI, Rapporto sul Bonijicamento delle Maremme Toscane, pp. xli., 
124. 
¢ Jl Politecnico, Milano, Aprile e Maggio, 1863, p. 35. 
