VOLUxVIE XXXIV 



NUMBER 3 



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Botanical Gazette 



SEPTEMBER, igo2 



THE RISE OF THE TRANSPIRATION STREAM: AN 



HISTORICAL AND CRITICAL DISCUSSION. 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 



XXXVIIL 



Edwin Bingham Copeland. 



(with one figure) 



K **I.e phenomene de Tascension dc la seve est reste jusqu' 

 a nos jours sans aucune explication plausible/' wrote Dutrochet 

 in 1837. Knight had said the same thing in 1801. During the 



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intervening century there have been a considerable number of 

 explanations, plausible enough to satisfy their authors, and a 

 very few which have commanded a \vide but temporary adher- 

 ence. Every theory proposed has been overthrown by direct 

 experiment, or shown to be in conflict with generally accepted 

 principles of physics. 



The work of Dixon and Joly and of Askenasy during the 

 past decade has extended the knowledge already possessed in 

 physics as to the cohesive power of water, and by the application 

 of this knowledge these authors have developed a theory which 

 has since almost monopolized the field. Believing that the true 

 solution was to be found in this direction, I set up an apparatus 

 intended to illustrate its application more strikingly than had 

 been done before. This artificial tree had so much in its behavior 

 in common with real trees that when all was done I was likewise 

 unable to explain it. 



Thirty-one pieces of glass tubing, each 3^"^ in diameter and 



161 



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