V. TRANSPIRATION 1 



A . Loss of Weight of a Growing Plant: 



Experiment i. Object: 2 To show that a living plant 



is constantly losing weight. 



i. Choose a well- watered, vigorous, potted plant. 

 Wrap the pot in sheet rubber or oilcloth (or paraf- 

 fined paper), and tie the wrapping about the stem 

 tightly, but not tightly enough to cause injury. 

 Place the plant thus prepared on a pair of balances 

 in a well-lighted window, and record its exact 

 weight in grams in the following table, which should 



Time 



Day 



Hour 



Weight in 

 grams 



be copied into your note-book. After weighing, 

 the window should be opened (if the weather is not 

 too cold) ; direct sunlight is also desirable. Record 



1 NOTE. Where the class is large, or the laboratory equipment limited, 

 and especially when the course extends over only one semester, it is rec- 

 ommended that most, if not all, of the physiological experiments outlined 

 in the remainder of Part I be performed by the instructor as demonstra- 

 tions in the presence of the class. 



2 For directions for recording an experiment see p. 4 of this GUIDE. 

 In each experiment this outline is to be filled out entire, without further 

 directions. 



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