PHYSIOLOGICAL PROCESSES IN PLANTS 41 



7. Note the broad base (ovary) of a pistil. Also find a more 

 or less stalklike portion (style) which, terminates in a rough- 

 ened sticky tip (stigma). Note. The stigma usually has upon 

 it a sweet, sticky substance in which pollen grains may grow 

 much as a seed would sprout. 



Conclusion. Do the stamens and pistils have the same or 

 different functions? Keasons for your answer? 



Drawings. 1. A flower from above. Label all parts. 



2. A stamen, showing all parts. 



3. A pistil, showing all parts. 



Observations (Home Work}. 1. Locate some flower buds. Care- 

 fully remove the calyx from one of them. After a time compare in de- 

 velopment with other buds. Result ? 



2. Remove the corolla from another bud. -Do insects visit it ? 



3. Remove the stigma from another young blossom. Effect on fruit 

 after a few weeks ? 



4. Cover a cluster of flower buds with a paper bag. Effect on fruit in 

 a few weeks ? 



Conclusion. Name a function of the calyx ; corolla ; stigma ; pollen 

 (as decided by experiment). 



b. Pollen 



Method. Dust-some buttercup pollen on a piece of paper, or 

 a glass slide. Examine it with a hand lens. Make a solution of 

 about 20 grams of sugar with about 80 grams of water. Make 

 another solution about one half as strong. Place some of 

 each solution in watch glasses, and dust some ripe pollen in 

 each. Place them under a small bell jar with a moist sponge, 

 and examine them from time to time with the low power of a 

 compound microscope. Also try tulip or narcissus pollen in 

 3% cane sugar solution, sweet pea or nasturtium pollen in 

 15% cane sugar solution. 



Note. Some prefer to make a "hanging drop" preparation 

 by placing a drop of the solution used with some pollen on a 

 cover glass and inverting it on a small ring which has been 

 placed on an ordinary slide. Seal it with vaseline, and watch 

 for sprouting pollen. 



