Oct. 4. i9is-Mar. 27. 1916 Illustrations xxi 



Page 

 Fig. 2. A portion of the same section of a potato plant shown in figure r, show- 

 ing the mycelium in the pith region of the stem 90 



3. A cross section of the cortical region of a potato stem, showing the 



mycelium of Phytophthora infestans 91 



An Automatic Transpiration Scale of Large Capacity for Use with 

 Freely Exposed Plants 



Fig. I. Vesque's automatic balance for measuring transpiration 118 



2. Anderson's apparatus for measuring transpiration 118 



3. Ganong's automatic transpirometer 119 



4. Woods's adaptation of Marvin's weighing rain gage as a transpiration 



balance 120 



5. The Marvin register used by Woods for recording transpiration 120 



6. Schematic diagram of Blackman and Paine 's recording transpirometer 121 



7. Krutizky's potometer for recording transpiration 121 



8. The transpiration balance of Richard Fr^res with its recording appara- 



tus 122 



9. Copeland 's apparatus for recording transpiration 123 



10. Corbett's apparatus for measuring transpiration 124 



11. View of the beam and auxiliary equipment of the platform transpira- 



tion scale designed to carry large pots of plants weighing 150 kgm. 



or more 125 



12. Details of the ball-dropping mechanism 126 



13. Dashpot for preventing the oscillation of the beam during windy 



weather 127 



14. Spring motor, showing the cam K for raising the beam, and the fan F 



for regulating the speed 127 



15. Another view of the spring motor, showing the control mechanism . . . 128 



16. Sample records from the automatic transpiration scale 129 



17. Wiring diagram of the electric circuits of the automatic transpiration 



scale 130 



18. Transpiration graphs corresponding to the three records given in figure 



16, plotted in rectangular coordinates 131 



Effect of Temperature on Movement of Water Vapor and Capillary 

 Moisture in Soils 



Fig. I. Apparatus for determining thermal translocation of soil moisture when 



the column of soil lay horizontally 142 



2. Apparatus for determining thermal translocation of soil moisture when 



the column of soil stood vertically 143 



3. Curve showing the movement of moisture from a warm to a cold col- 



umn of soil of uniform moisture content 146 



4. Diagram illustrating the cause and mechanism of moisture movement 



from a warm to a cold column of soil of uniform moisture content. . . 151 



5. Curve showing the percentage of moisture moved from a moist and 



warm column to a dry and cold column of quartz sand, and from a 

 moist and cold to a dry and warm column of quartz sand 162 



6. Curve showing the percentage of moisture moved from a moist and 



warm column to a dry and cold column of Miami sandy loam, and 

 from a moist and cold to a dry and warm column of Miami sandy 

 loam 162 



7. Curve showing the percentage of moisture moved from a moist and 



warm column to a dry and cold column of heavy sandy loam, and 

 from a moist and cold to a dry and warm column of heavy sandy 

 loam 163 



