100 PHYSIOLOGICAL PROCESSES IN PLANTS 



Conclusions. 1. Does starch remain where it is manufac- 

 tured ? 



2. What has caused it to apparently disappear ? 



3. What has become of it? (See Prob. XVII.) (Condition 

 of food as it passes through the stem.) 



3. EVAPORATION OF EXCESS WATER (TRANSPIRATION) 



Method a. Cover a flower pot in which a vigorous leafy 

 plant (a rubber plant or geranium, for example) is growing, 



with a rubber cloth so that 

 only steins and leaves are 

 exposed as in Figure 29. 

 Water the plant well be- 

 fore fastening the cloth. 

 (a) Place the pot under a 

 bell jar; or (6) place it in a 

 sunny place on a balance, 

 and note the position of the 

 pans from time to time. 



Observations. 1. What 

 collects on the inner sur- 

 face of the jar? 



2. What is the loss of 

 weight of the plant ? 



Conclusion. Write the 

 conclusion that fits the ob- 

 servation made. 



Note. The giving off 

 through the leaves of the 



exce8S water f 



FIG. 29. Experiment to show transpira- 

 tion. Note the roots covered with root thesis is called transpira- 

 hairs growing from the main stem of the tion. 



plant. Explain their origin. Observation. Remove 



two large leaves from a plant, such as a rubber plant. See 

 that they are of about the same size and weight. Cover 

 the upper surface of one and the lower surface of the other 



