7 88 THE POPULAR SCIENCE MONTHLY. 



Sometimes a twofold drainage of the upper, as well as the under 

 aspect of the soil may be practiced that is, draining the subsoil and 

 increasing the evaporation of the surface water. The cutting down 

 of forests in malarious countries has often proved an excellent means 

 of amelioration ; because, by removing every obstacle to the direct 

 action of the sun's rays on the surface of the soil, its humidity during 

 the warm season is sometimes entirely exhausted. In spite of univer- 

 sal experience of this fact, a school originating with the great Roman 

 physician, Lancisi, has sustained the contrary, counseling the mainte- 

 nance and even the extension of forests in malarious countries. Lan- 

 cisi was completely possessed with the " palustral prejudice," and be- 

 lieved that the malaria generated in the Pomptine Marshes, and 

 attacking such townships as Cisterna, was intercepted, if only partially, 

 by the forests between, and he therefore opposed the cutting down of 

 the trees and recommended increased planting. He did not know that 

 the malaria was already in the soil and covered by the forest in ques- 

 tion. Some thirty years ago the Caetani family, to whom Cisterna be- 

 longs, cut down the forest, and twenty years thereafter Dr. Tommasi- 

 Crudeli was able to show that the health of the neighborhood had 

 greatly improved in consequence. A commission appointed by the 

 Minister of Agriculture investigated the whole subject of the coexist- 

 ence of woods with malaria, and in its report issued in 1884 completely 

 disproved the theory of Lancisi and confirmed that of Dr. Tommasi- 

 Crudeli. 



Absorbent plants have been suggested and used as a means of 

 drawing humidity from the soil, not without success in certain coun- 

 tries really malarious. The prejudice that the malaria is due to the 

 putrescent decompositions of the soil has, in Italy, led to the choice 

 of the Eucalyptus globulus as the tree best adapted to combat the 

 poison, the idea being that the eucalyptus, which grows very rapidly, 

 dries the humid earth, and at the same time by the aroma of its leaves 

 destroys the so-called miasmata. No genuine instance of the eucalyp- 

 tus having succeeded in its allotted task is yet known to Dr. Tommasi- 

 Crudeli, though he does not say that its success is impossible. Had 

 its Italian patrons studied its action in its native Australia, where it 

 flourishes much better than in Italy, they would have known that there 

 are eucalyptus forests in those latitudes where malaria is very preva- 

 lent, as has been shown by Professor Liversidge, of the University of 

 Sydney. The cultivation of the tree at the Tre Fontane, near Rome, 

 which it was thought would prove entirely successful in combating the 

 local malaria, disappointed expectations, for in 1882 that hamlet was 

 the scene of a severe outbreak of the fever, while the rest of the Cam- 

 pagna was unusually exempt from it. The eucalyptus, in fact, is a ca- 

 pricious tree in European soil ; while in full leaf, during the winter, 

 it is often killed by nocturnal frost, and even by the late frosts of 

 spring, to say nothing of humid cold and other adverse influences not 



