LIST OF ILLUSTRATIONS. 5 



15. Movement in lower stomata of potato under (A) high water-content and moderate 



evaporation, (B) low water-content and moderate evaporation, and (C) low 

 water-content and excessive evaporation. 



16. Series 11, weather data for June 20-21, 1916. 



17. Series 11, showing movement in upper and lower stomata of sugar-beet. 



18. Series 16, weather data for July 26-27, 1916. 



19. Series 16, showing effect on movement of reversing the leaves of sugar-beet. 



20. Series 16, showing movement in stomata of onion, and upper stomata of alfalfa. 



21. Series 2, showing movement in lower stomata of oats and of barley. 



22. Series 3, showing movement in lower stomata of oats and of barley, and upper sto- 



mata of alfalfa. 



23. Series 10, showing movement in lower stomata of wheat, barley, and oats. 



24. Series 11, showing movement in lower stomata of wheat, oats, and barley. 



25. Series 11, showing movement in lower stomata of corn and millet. 



26. Series 26, showing movement in lower stomata of wheat growing in the greenhouse. 



27. Series 6, showing movement in lower stomata of Lombardy poplar, and starch-index 



of the guard-cells. 



28. Series 7, showing movement in lower stomata of Rumex patientia, and starch-index 



of the guard-cells. 



29. Series 10, showing movement in upper stomata of alfalfa, and starch-index of the 



guard-cells. 



30. Relation of speed of total opening to temperature. 



31. Series 34, factor data for September 10-11, 1919. 



32. Series 33, showing evaporation, transpiration, and the factors concerned for September 



8-9, 1919. 



33. Series 33, showing evaporation from white-cylinder porous-cup in cubic centimeters 



per hour, compared with product of vapor-pressure deficit and wind velocity, 

 calculated by Johnston's method. 



34. Series 35, showing stomatal movement in heavily watered plants of alfalfa, the 



partial closure at 8 and 10 a. m. following the disappearance of the dew. 



35. ''Relative transpiration" based on evaporation from blotting-paper atmometer and 



from white-cylinder porous-cup, compared with stomatal movement in the onion . 



36. Effect of water-content on movement in the upper stomata of alfalfa. 



37. Series 17, weather data for August 8-9, 1916. 



38. Series 17, showing average movement of alfalfa stomata in watered and unwatered 



field plants, and in cut stems. 



39. Series 17, showing stomatal movement and transpiration in cut stems of alfalfa. 



40. Series 20, weather data for August 25-26, 1916. 



41. Series 20, showing movement in upper and lower stomata of potted potato plants, 



and in upper and lower stomata of cut potato stems. 



42. Series 20, showing movement in upper and lower stomata of heavily watered potato 



plants, and in upper and lower stomata of plants in very dry soil. 



43. Series 20, showing average stomatal movement and transpiration in cut stems of potato. 



44. Series 29, weather data for March 15-16, 1918. 



45. Series 29, showing average movement in upper and lower stomata of watered and 



unwatered field plants and in cut stems of Fouquiera splendens. 



46. Series 29, showing average movement in upper and lower stomata of field plants, 



and cut stems of Verbena ciliata. 



47. Series 29, showing stomatal movement and transpiration in cut stems of Fouquiera 



splendens. 



48. Series 29, showing stomatal movement and transpiration in cut stems of Verbena ciliata. 



49. Series 32, weather data for August 25-26, 1919. 



50. Series 32, showing stomatal movement averaged for 2-hour periods, and trans- 



piration in milligrams per minute for the same periods in heavily watered potted 

 plants of alfalfa. 



51. Series 32, showing stomatal movement averaged per 2-hour period, and trans- 



piration in milligrams per minute of dry alfalfa phytometers. 



52. Series 32, showing transpiration of wet and dry alfalfa phytometers. 



53. Series 33, showing average movement of upper and lower stomata, and transpiration 



of cow-beets in dry pots. 



54. Series 33, showing transpiration from potted cow-beets in dry pots and from potometers. 



