PHYSIOLOGY 



493 



Leguminosae, this change of position is temporary; but in some 

 xerophytes, which are exposed for 

 prolonged periods to great heat and 

 light, the leaf may permanently 

 assume a vertical position. This is 

 well shown in most 

 species of Eucalyp- 

 tus, and in Arcto- 

 stapliylos Manzanita 

 (Fig. 463). 

 phyllodia of 

 Acacias also 



The 

 many 

 illus- 

 trate this. 



Electric Stimuli. 

 While plants are 

 undoubtedly affected 

 by electric stimuli, 

 the reactions are not 

 nearly so obvious as 

 are those resulting 

 from the stimulus of 

 light or heat, nor are 

 they ordinarily of 

 any value to the 

 plant. The study of 

 electric stimuli re- 

 quires further inves- 

 tigation. 



FIG. 464. Viola rostrata. A, normal plant. (After 

 BRITTON and BROWN.) B, plant of the same species 

 grown in the dark. (After MACDOUGAL.) 



BIBLIOGRAPHY 



'95. 1. Askenasy. Ueber das Saftsteigen. Verhandl. d. naturwiss. Vereins 



in Heidelberg. 1895. 



'99. 2. Brown, H.T. The Fixation of Carbon by Plants. Nature. Sept., 1899. 

 '97. 3. Copeland, E. B. Relation of Nutrient Salts to Turgor. Bot. Gaz., 



XXIV. 1897. 

 '00. 4. Czapek, F. Kohlensaure-Assimilation und Chlorophyll. Bot. Zeit., 



LVIII. 1900. Includes bibliography of the most recent work on 



the subject. 

 '97-'99. 5. Davenport, C. B. Experimental Morphology. New York, 1897- 



1899. Includes extensive bibliography. 

 '94. 6. Dixon, H. H., and Joly, J. On the Ascent of Sap. Ann. of Bot., 



VIII. 1894. 



'95. 7. - The Path of the Transpiration-Current. Ann. of Bot., IX. 1895. 

 '97. 8. Ewart, A. J. On the Evolution of Oxygen from Colored Bacteria. 



Jour. Linn. Soc., XXXIII. London, 1897. 



'01. 9. Fischer, A. Structure and Functions of Bacteria. Oxford, 1901. 

 '92. 10. Frank, A. B. Lehrbuch der Botanik. Leipzig, 1892. 



