246 



INDEX. 



Carboniferous period, composition 



of the atmosphere during, 144. 

 Caterpillars, destruction of forests 



by, 73, 74. 

 Cause of deserts, 42. 



of meadows and prairies, 43. 

 of steppe regions, 43. 

 Classes of land suitable for main- 

 tenance of forests, 158, 159. 

 Clayey soils, definition of, 50, 51. 

 Climate, definition of, 119. 



influence of elevation of land 



on, 121, 122. 

 influence of land and water 



areas on, 120, 121. 

 influence of the presence of 



the forest on, 127 to 133. 

 influences producing variations 



in, 120, 121, 122. 

 of forest region, characteristics 



of, 124. 



peculiarities of continental, 123. 

 peculiarities of oceanic, 123. 

 Comparative unimportance of soil 



for plant growth, 25. 

 Conditions influencing the rapidity 

 of spread of forest fires, 65, 

 66. 

 necessary for the growth of 



plants, 20 to 24. 

 necessary for the growth of 



trees, 42 to 47. 

 required for the production of 



rain, 101. 



Continental climate, peculiarities 

 of, 123. 



D. 



Dana, James D., extract from his 

 " Manual of Geology," 70, 145, 

 146. 



Decaying leaves, influence of, on 



disintegration of rocks, 57. 

 Decomposition of carbonic acid in 



plants by sunshine, 22. 

 Definition of assimilation, 32. 



of forestry, 9. 



Deforestation and reforestation, 14. 

 Deserts, cause of, 42. 

 Destruction of forests, 81 to 86. 

 by fire, 64, 65, 66. 

 evil results following, 



81, 82. 

 Disintegration of rocks, agencies 



causing, 52, 53. 



Distant planets, possibilities as to 

 the existence of life thereon, 98. 

 Distinctive flora of particular re- 

 gions, meaning of, 30. 

 Distribution of heat, influence of, 

 by destruction of forests, 84. 

 of solar energy, how affected, 



170, 171. 

 Domestic and domesticated plant 



species, 33. 

 Drainage, 109 to 113. 

 definition of, 109. 

 influence of mountains on, 16. 

 surface, definition of, 110. 

 underground, definition of, 110. 

 Droughts, caused by destruction of 



forests, 81. 



E. 



Earth's ocean of vapor, 90 to 97. 



Earthworm, influence of, in forma- 

 tion of soil, 56. 



Egyptian mummies, reputed pres- 

 ervation of plant seeds in, 33. 



Electrical theory of hail, 149, 150 



Equatorial currents of air, why 

 rain-bearing, 101. 



