Water in Plants — xi — Preface 



Reviewing plant-water relations, Tageeva (1946) found that wheat plants have 

 reduced water content as they mature ; upper leaves dehydrate more than lower ones. 

 Nevertheless, the upper leaves have a greater rate of photosynthesis than lower ones. 

 Low water supply results in an increase in soluble carbohydrates leading to decrease 

 in photosynthesis. Eaton and Ergle (1948) find that in certain plants such as cotton, 

 water deficit may depress carbohydrate utilization to a greater extent than it does 

 photosynthesis leading to an increased sugar content. 



In the discussion mentioned above (Faraday Soc. Discussion, 1948) papers by 

 VAN DEN HoNERT, LEWIS, FoGG, and Crafts deal with water and food movement in 

 plants and the relations of leaf cell walls and leaf surfaces. Van den Honert, con- 

 sidering the role of living root cells, xylem conductors, living leaf cells and the 

 "gaseous part" (intercellular spaces, stomata, and air layer around the leaf) concludes 

 that the greatest resistance to water movement is the "gaseous part." He agrees 

 with Gradmann's (1928) views that this phase may exert limiting influence on water 

 transport. 



Lewis presents further data on the hydrophobic nature of the outer walls of leaf 

 mesophyll, while Fogg pictures the effects of varying water conditions of underlying 

 tissues on the nature of the leaf surface. 



Crafts, in an analysis of the physical nature of sieve-tube protoplasm, and sieve 

 tube walls, concludes that the mature, functioning sieve tube is a highly specialized 

 structure. The optical nature of the walls and their high water content suggest that 

 they have a loose open structure. The degradation of the sieve-tube cytoplasm at- 

 tending maturation of these elements results in a loss of their semipermeability. It 

 is concluded that this also denotes an open mesh structure. It is suggested that the 

 open structure of sieve-tube walls and cytoplasm constitute specialization favoring a 

 mass flow of the assimilate stream. Went and Hull (1949) present evidence for a 

 temperature coefficient of less than 1 for both rate and intensity of sugar transport in 

 the tomato plant. 



The perplexing problem of stomatal behavior was reviewed critically by Wilson 

 (1948a). Theories proposing that stomatal action can be accounted for by changes in 

 permeability, changes in enzyme activity, or variation in colloidal hydration were not 

 considered adequate as an explanation for the observed effects of light, temperature, 

 and humidity on stomatal aperture. 



Literature cited: — Audus, L. J. 1949: Biol. Rev. 24: 51-93. — Burstrom, H. 1948: Physiol. 

 Plant. 1: 57-64.— Crafts, A. S. 1943: Chronica Bot. 7: 386-8.— Daniel, T. W. 1949: Plant 

 Physiol. 24: 327-30. — Eaton, F. M., and D. R. Ergle 1948: Plant Physiol. 23: 169-87. — Fara- 

 day Soc. Discussions No. 3, 1948: 1-293. — Faraday Soc. Trans. 1946, 42B: 1-304. — Franck, J., 

 and J. E. Mayer 1947: Archives of Biochem. 14: 293-313. — Frey-Wyssling, A. 1941: Ber. 

 Schweiz. bot. Gas. 51: 321. — Gessner, F., and M. Schumann 1948: Z. Naturforsch. 3b: 36-41. — 

 Gradmann, H. 1928: Jahrb. wiss. Bot. 69: 1-100. — Grossenbacher, K. A. 1938: Plant Physiol. 

 13: 669-76. — Hagan, R. M. 1949: Plant Physiol. 24: 441-454. — Haynes, J. L. 1948: Jour. Amer. 

 Soc. Agron. 40: 385-95. — Kelly, S. 1947: Amer. Jour. Bot. 34: 521-6. — Levitt, J. 1947: Plant 

 Physiol. 22: 514-25. — Levitt, J. 1948: Plant Physiol. 23: 505-15. — Mitscherlich, E. A. 1947: 

 Z. Pflanzenernahr., Dungung u. Bodenk. 38: 202-15. — Morton, A. G., and D. J. Watson 1948: 

 Ann. Bot. 12: 281-310. — Osterhout, W. J. V. 1949: Jour. Gen. Physiol. 32: 553-66. — Palmer, 

 G. 1948: Ind. Eng. Chem. 40: 89-92. — Parshad, R. 1947: Jour. Phys. Chem. 15: 761-2. — Red- 

 LicH, O. 1949: Chem. Rev. 44: 1-5. — Scott, A. F., D. P. Shoemaker, K. N. Tanner, and J. G. 

 Wendel 1948: Jour. Chem. Phys. 16: 495-502. — Searcy, A. W. 1949: Jour. Chem. Phys. 17: 

 210-11. — Simha, R., and J. W. Rowen 1948: Jour. Amer. Chem. Soc. 70: 1663-5. — Taft, R. W. 

 and H. H. Sisler 1947: Jour. Chem. Educ. 24: 175-81. — Tageeva. S. V. 1946: Trudy Inst. 

 Fiziol. Rastenii un K. A. Timiryazeva 4, No. 1: 161-75 and 176-92. — Temperley, H. N. V. 1947: 

 Proc. Phys. Soc. (London) 59: 199-208. — Volk, A. 1944: Bodenk. u. Pflanzenernahr. 34: 190-204. 

 — Wadleigh, C. H. 1945: Soil Sci. 61: 225-38. — Wadleigh, C. H., and H. G. Gauch 1948: 

 Plant Physiol. 23: 485-95. — Weissler, A. 1947: Jour. Chem. Phys. IS: 210-11. — Went, F. W., 

 and H. M. Hull 1949: Plant Physiol. 24: 505-26. — Wilson, C. C. 1948o: Plant Physiol. 23: 

 5-37. — Wilson, C. C. 1948b: Plant Physiol. 23: 156-7. — Woestmann, E. 1942: Jahrb. wiss. 

 Bot. 90: 335-81. 



July 1949 The Authors 



'^j LIBRAR , 



'" '' V MASS. / '>. 





