xxii LIST OF ILLUSTRATIONS AND DIAGRAMS 



FIG. PAGE 



25. Diagram of relative amounts of organic matter, and of the 



incubation periods of seeds, in heated soils . . .251 



26. Plants growing in soils heated to different temperatures . 255 



2/- )5 )) 5) 5) )) 5) ' -O^ 



28. Diagram of growth of grasses and non-grasses in soils heated 



to different temperatures . . . . .258 



29. Bramley standard apple trees in grass and in tilled soil . . 260 



30. Bramley bush apple trees in grass and in tilled soil . .261 



31. Cox's Orange apple trees grassed after four years . . . 263 



32. Standard trees grassed after twenty-three years . . . 264 



33. Pears in grass and in tilled soil .... . 266 



34. Plums in grass and in tilled soil ...... 267 



35. Cherries in grass and in tilled soil ..... 269 



36. Trees growing with their roots buried 13 feet deep . . 277 



37. Diagram showing the distribution of fine particles in grassed 



and tilled soil . . . . . . . .281 



38. Diagram showing the variation in the water contents of grassed 



and tilled soil ........ 283 



Plate IV Snow scene, April 25, 1908 . . 290 



39. Pots used in pot experiments ...... 292 



40. Plants grown in pots with and without a surface crop . . 294 



41. Mustard in pots with and without a surface crop . . . 295 



42. Effect of a surface crop grown in perforated and unperforated 



trays .......... 299 



43. Effect of weeds on a tree, and its recovery on their removal . 305 



44. Roots of trees of the crab and pear stock in the Ridgmont soil 309 



45. Plants grown at different distances apart . . . .316 



46. Diagram of distribution of soil particles compared with rainfall 327 



47. Paradise and crab roots, and trees grown on these stocks . 331 



