GENEEAL FUNCTIONS OF FORESTS. 291 



the gray and dewy morning calls the creeping things of the earth 

 out of their night-cells, it summons from the neighboring wood 

 legions of their winged enemies, which swoop down upon the 

 fields to save man's harvests by devouring the destroying worm, 

 and surprising the lagging beetle in his tardy retreat to the dark 

 cover where he Im-ks through the hours of daylight. 



The insects most injurious to the rural industry of the garden 

 and the ploughland do not multiply in or near the woods. The 

 locust, wliich ravages the East with its voracious armies, is bred 

 in vast open plains which admit the full heat of the sun to hasten 

 the hatching of the eggs, gather no moisture to destroy them, 

 and harbor no bird to feed upon the larvae.* It is only since the 

 felling of the forests of Asia Minor and Cyi*ene that the locust 

 has become so fearfully destructive in those countries ; and the 

 grasshopper, which now threatens to be almost as great a pest to 

 the agriculture of some North American soils, breeds in seriously 

 injurious numbers only where a wide extent of surface is bare of 

 woods. 



General Functions of Forests. 



In the preceding pages we have seen that the electrical and 

 chemical action of the forest, though obscure, exercises probably 

 a beneficial, certainly not an injurious, influence on the composi- 

 tion and condition of the atmosphere ; that it serves as a protec- 

 tion against the diffusion of miasmatic exhalations and nialarious 

 poisons ; that it performs a most important function as a mechan- 

 ical shelter from blasting winds to grounds and crops in the lee 

 of it ; that, as a conductor of heat, it tends to equahze the tem- 

 perature of the earth and the air ; that its dead products form a 

 mantle over the surface, which protects the earth from excessive 

 heat and cold; that the evaporation from the leaves of hving 



* Smela, in the government of Kiew, lias, for some years, not suffered at all 

 from the locusts, which formerly came every year in vast swarms, and the 

 curculio, so injurious to the turnip crops, is less destructive there than in 

 other parts of the province. This improvement is owing partly to the more 

 thorough cultivation of the soil, partly to the groves which are interspersed 



among the ploughlands When in the midst of the plains woods shall 



be planted and filled with insectivorous birds, the locusts will cease to be a 

 plague and a terror to the farmer. — Rentzsch, Der Wald, pp. 45, 46. 



