LIST OF ILLUSTRATIONS 



1. Drawing to show how the plant receives its several food 



elements .......... 4 



2. Effects of temperature on germination 9 



3. Effects of ventilation on germination 15 



4. Effects of ventilation on germination . . . . .16 



5. Effects of ventilation on germination . ... .17 



6. Effects of ventilation on germination ..... 18 



7. A mass of soil particles surrounded by capillary film, shown 



in section 27 



8. A mass of sandy loam formed under pressure of the hand 



and held in shape by capillary moisture .... 30 



9. Same soil as shown in Fig. 8, but after a slight pressure of 



the fingers was applied 30 



10. A mass of the same soil as is shown in Fig. 8, but with an 



over-amount of capillary moisture, as is proven in Fig. 11 31 



11. Same soil as is shown in Fig. 10 32 



12. Illustrating soil crumbs 32 



13. Chart indicating diagrammatically the number of English 



heat units required to raise the amount of water, the 

 amount of dry soil, and the combinations of soil and 

 water, respectively, shown in the lower part of the chart, 

 33 in temperature 35 



14. Chart showing the effect of a given amount of heat in raising 



the temperature of soils with different water content . 37 



15. Chart showing the temperature effects of the heat required 



to raise three types of soil with their normal water con- 

 tent from 32 F. to 65 F. of temperature ... 38 



16. The effect of lumps lying on the surface of a field . . 42 



17. A mass of sand loam held in shape by a capillary film . . 45 



18. Pyramid of sandy loam held in position by a capillary film . 45 



19. The appearance of a recently plowed soil mass when the 



plowing has been performed with the soil in proper 

 capillary moisture condition ... . . . 46 



