OUR FORESTS 135 



" At first these rains, sweeping down torrentially, unhindered by the 

 lost forests, only enriched the plain with the long-hoarded sweetness of 

 the trees ; but by and by the living rivers grew heavy and thick, vomiting 

 mud into the ever shallowing harbors, and the land soured with the un- 

 drained stagnant water. Commerce turned more and more to deeper 

 ports, and mosquitoes began to breed in the brackish soil that was making 

 fast between the city and the sea. 



" Who of all those powerful landowners and rich merchants could ever 

 have dreamed that little buzzing insects could sting a great city to death ? 

 But they did. Fevers grew more and more prevalent. The malaria- 

 haunted population went more and more languidly about then* business. 

 The natives, hardy and vigorous in the hills, were but feebly repulsed. 

 Carthage demanded tribute, and Rome took it, and changed the city's 

 name from Poseidonia to Paestum. After Rome grew weak, Saracen 

 corsairs came in by sea and grasped the slackly defended riches, and the 

 little winged poisoners of the night struck again and again, until grass 

 grew in the streets, and the wharves crumbled where they stood. Finally, 

 the wretched remnant of a great people wandered away into the more 

 wholesome hills, the marshes rotted in the heat and grew up in coarse 

 reeds where corn and vine had flourished, and the city melted back into 

 the wasted earth." 



Elizabeth Bisland and Anne Hoyt, Seekers in Sicily. John Lane Company. 



Prevention of Erosion by Covering of Organic Soil. We have 

 shown how ungoverned streams might dig out soil and carry it 

 far from its original source. Examples of what streams have done 

 may be seen in the deltas formed at the mouths of great rivers. 

 The forest prevents this by holding the water supply and letting it 

 out gradually. This it does by covering the inorganic soil with 

 humus or decayed organic material. In this way the forest 

 floor becomes like a sponge, holding water through long periods 

 of drought. The roots of the trees, too, help hold the soil in place. 

 The gradual evaporation of water through the stomata of the leaves 

 cools the atmosphere, and this tends to precipitate the moisture 

 in the air. Eventually the dead bodies of the trees themselves are 

 added to the organic covering, and new trees take their place. 



Other Uses of the Forest. In some localities forests are used as 

 windbreaks and to protect mountain towns against avalanches. 

 In winter they moderate the cold, and in summer reduce the heat 

 and lessen the danger from storms. The nesting of birds in woods 

 protects many plants valuable to man which otherwise might be 

 destroyed by insects. 



