PHYSIOLOGICAL PROCESSES IN PLANTS 



69 



4. Suppose an increased yield is desired. What results from culling 

 the barren stalks ? When should they be culled ? 



5. Suppose quality, such as a greater percentage of oil, is desired. 

 Test a kernel for oil. What part contains most of the oil ? How should 

 you select ears to develop this quality ? What does the white part of the 

 kernel contain ? How select to develop this quality ? What is most of 

 the rest of the kernel around the germ ? How develop this quality? 



6. Suppose you wished to develop, size, shape, color, etc. How de- 

 velop these qualities ? 



7. It may be desirable to select a sort that is hardy and ripens early. 

 The original home of corn was in Central America. How develop hardi- 

 ness and early ripening ability ? 



8. Can corn now be grown on the great alkali plains ? How might a 

 race of corn resistant to drought be produced ? 



9. A great amount of damage is annually done by corn smut. How 

 might a resistant variety be produced ? See Hunter, Essentials of Biol- 

 ogy, p. 81. 



d. Artificial Cross-pollination 



Observations. 1 . Tie up a tulip or lily flower bud about ready to open 

 with a manila bag, so that there will be no danger of foreign pollen being 

 transferred there by bees, wind, or other 

 foreign agents. 



2. Remove the corolla and stamens en- 

 tirely from the pistil of another tulip or lily 

 bud of another sort, being careful to cut 

 the stamens away before the flowers have 

 opened, thus leaving the pistil alone on the 

 receptacle. (Cut at the line marked "W" 

 in Figure 14.) 



3. As soon as the blossom in the bag 

 opens, transfer some of the pollen to the 

 stigma of the flower without stamens. This 

 is best done by crushing a ripe anther upon 

 the finger nail, and then transferring it to 

 the stigma by means of a small scalpel made 



by hammering out the pointed end of a pin. ^ 14> _ ghowi how to 



A camePs-hair brush may also be used. See cut away the gtamens and 



that the stigma is entirely covered with coro n a of a blossom, for 



pollen. Label the stigma thus pollinated, artifical cross-pollination, 



stating the date, from what pollinated, etc. (After Bailey.) 



