Not only are lava, peperino, and the volcanic puzzuolana abundant, but in many places—as at Bracciano and Baccano—are to be seen the remains of ancient craters. When the Campagna was in the earliest phase of its history, it was one fertile garden, interspersed with thriving towns and villages. It was also the theatre of events which terminated in making Rome the mistress of the world. This very supremacy was the final cause of its ruin and of its present desolation. While the land remained in the possession of small holders every acre was assiduously tilled and drained; but when it passed into the hands of large landed proprietors, who held it from the mere lust of possession, it became uncared for and uncultivated.
Filtering into a soil loaded with easily decomposed sulphur compounds, the decomposing vegetable matter finds no exit through the underlying rock. The consequences may be imagined, but, to those who have not experienced them, are not easily described. This once fertile land is now a horrid waste, untouched, except at rare intervals, by the hand of the farmer, and untenanted save by the herdsman. Even he, during the months of summer, when the malaria is at its worst, is compelled, if he will avoid the fever, to go with his flocks to the mountains. It may be mentioned, in passing, that the malaria fever, or "Roman fever" as it has been called, has been the subject of recent investigation by Professor Tommassi-Crudelli, of Rome, who attributes it to the presence of an organism, to which the specific name of Bacillus malariæ has been given.
Leaving St. Paul's, we pursued for a short time the Ostian road; and at a poor osteria, where chestnuts, coarse bread, and wine, were the only obtainable refreshments, our route turned to the left, along a road powdered with the reddish dust of the pozzuolana—the mineral which forms the basis of the original "Roman cement"—large masses of which rock form the roadside fences. After a drive of perhaps half an hour, we found ourselves at the Monastery of Tre Fontane (three fountains). The Abbey of the Tre Fontane comprises within its precincts three churches, of which the earliest dates from the ninth century. One of these, San Paolo alle Tre Fontane, gives its name to the monastery. A monk, wearing the brown robe and sandals of the Trappist order, met us at the gate. The contrast now presented between the sterile semi-volcanic country around and the smiling oasis which faces us, is striking. Here are fields which have borne good grass; some sloping hills covered with vines; and, directly in the foreground, almost a forest of eucalypt-trees.
We have come to learn about eucalypts; and our guide takes quite kindly to the role of informant. What follows is derived from his viva voce teaching, from my own observation on the spot, and from a very interesting pamphlet, printed at Rome in 1879, and entitled "Culture de l'Eucalyptus aux Trois Fontanes," by M. Auguste Vallée.