222 



EXPERIMENTS WITH FLOWERS 



Method. Select some buds which are about to open. 

 Note the temperature of the air. Put them in a cold place, 

 such as a refrigerator, or in a stoppered bottle which is 

 immersed in a pail of ice water. The latter is better, since 

 the light is not shut off- as it is in a refrigerator. Repeat 



the experiment, using an open 

 flower instead of a bud. Remove 

 the bud to a warmer place and 

 note the result. Try the exercise 

 with different flowers. Are all 

 equally sensitive? Make the ex- 

 periment with only slight changes 

 of temperature. Procure, if pos- 

 sible, a flower of night-blooming 



12 c - 22 c - cereus or any other night-bloom- 



FIG. 97. Star-of-Bethlehem. , ^ , c 



ing plant. Cut the flower trom 



the stem at night when it is in full bloom and transfer it 

 immediately to a cold dark place. It may be kept open 

 for a long time in this way. Flowers of Phyllocactus lati- 

 frons have been kept open for thirty-six hours in this way. 



Conclusion. State what is to be inferred as to the effect 

 of temperature on opening and closing of flowers. 



Query. From your observations, which do you think 

 is the more potent cause of these phenomena in flowers, 

 light or heat ? Give reason for your answer. 



189. RESPIRATION OF FLOWERS 

 Object. Tb find out what is given off by flowers. 



Apparatus. Some half-open flowers of such plants as dandelion, 

 daisy, or elder, two wide-mouth bottles, corks, and materials for 

 testing gases. 



