TRANSPIRA 7/CW. 7 7 



B. Transfer (/>) of JUaboratcd Substances. 



39. What is the path and the physics of the transfer of 

 elaborated food-substances ? 



No experiment is here practicable upon this subject. It is 

 to be worked up theoretically, and expressed in a concise para- 

 graph. (Note Detmer-Moor, 35 1-359.) Construct a diagram 

 showing the structure of this system. 



The well-known constriction-experiment, proving the descent of 

 food-materials in the bark, is easy of trial in summer. 



CORRELATED TOPICS. 

 The theories of sap ascent. 

 Use of ferments. 



Ecological uses of hygroscopic absorption and transfer of water. 

 The latex system. 



LITERATURE. 

 AYard, H. M. Timber and some of its Diseases. London, 



1893. (Chapter IV. ) 

 Darwin, F., and others. Discussion on Ascent of Sap. 



Annals of Botany, 1896. 

 Review of Strasburger's " Leitungsbahnen in Annals of 



Botany, 1892, 227. 

 Noll, F., in the Bonn Text-book. 



C. Transpiration. 



Your earlier experiments have proven that large quantities 

 of water are absorbed by roots and passed up stems. The 

 question next arises, what becomes of it ? Is any of it given 

 off into the air from the leaves, and if so, how much ? 



40. Is water given oif by the leaves of a common plant grow- 

 ing under normal conditions, and if so, in what amount? 



Answer by Experiment 19. 



EXPERIMENT 19. To test this, a method must be used by which 

 loss of water from leaves of an uninjured plant may be exactly cal- 

 culated. For this a potted plant is convenient, but, obviously, evap- 

 oration from the soil and pot must be prevented. Take a Ricinus 



