114 Plant Physiology 



The rate of movement may be studied by leaving the shoots 

 from half an hour to one hour in the dye, then cutting off the 

 stems at successive intervals until the uppermost indication of 

 the stain is found, through examination with a hand lens. After 

 determining the rate of rise of the liquid at laboratory tempera- 

 ture, place some shoots under conditions favorable for rapid 

 transpiration and others under a bell glass, and contrast the 

 results. According to the directions in the next paragraph 1 de- 

 colorize a leaf of the grape, sunflower, or fuchsia, and under the 

 low power of the microscope study the minute ramifications of 

 the veins. 



Place fresh tissue in equal parts of 95 per cent alcohol and 

 glacial acetic acid. After from 24 to 48 hours, take pieces and 

 hold them immersed in pure nitric acid until clear (usually a 

 matter of seconds), place on a slide, add glycerin, and boil 

 over flame until tissue becomes entirely transparent. Put on 

 cover glass and examine in the glycerin. 



Ring small plants such as geranium, sunflower, Ricinus, or 

 other forms with definite bark, by removing a circle of bark 

 about one fifth of an inch long, extending completely around 

 the stem. The plants should not be in an atmosphere so ex- 

 treme as to cause rapid drying-out from the cut surface. Does 

 ringing interfere with the conduction of water to the leaves ? 



REFERENCES 



BURGERSTEIN, A. Die Transpiration der Pflanzen. 142 pp., 



14 pis., 1904. 

 CLAPP, G. L. A Quantitative Study of Transpiration. Bot. 



Gaz. 45 : 254-267, 32 figs., 1908. 

 CLEMENTS, E. S. The Relation of Leaf Structure to Physical 



Factors. Trans. Am. Mic. Soc. (1905) : 19-102, 9 pis. 

 COPELAND, E. B. The Rise of the Transpiration Stream. Bot. 



Gaz. 34 : 161-193 ; 260-283, 1902. 



1 A method suggested by Professor H. M. Benedict, University of 

 Cincinnati. 



