have germinated, remove from several of the corn seedlings varying fractions of 

 the endosperm, up to half or more, leaving some uncut; and remove from several 

 of the bean seedlings varying fractions of the cotyledon, up to half or more, leav- 

 ing some undisturbed. Return to the germinating dish; cover and leave for several 

 days longer. Compare the amount of growth in the various seedlings, with rela- 

 tion to the amount of endosperm or cotyledon removed. Tabulate the results and 

 note conclusions. 



QUESTIONS 



1 What are the essential organs of a flower .f* 



2 How do the sperm nuclei within the pollen get from the stigma to the 

 ovule? 



3 In what different ways is pollen transferred from the anthers to the stigma 

 in flowering plants? 



4 What are the advantages of self-pollenation ? of cross-pollenation? What 

 structures in different plants favor self-pollenation? favor cross-pollenation? 



5 In what respects is reproduction in flowering plants more advanced than 

 that in ferns? 



6 How do spores differ from seeds? In what ways are they alike? 



7 In what ways are seeds and fertilized eggs alike? different? 



8 What are the advantages to a species of producing a relatively large 

 number of eggs or seeds? the disadvantages? 



9 To what risks or dangers are eggs and the young of plants or animals 

 exposed ? 



10 In what sense can plants be said to care for their young? 



416 



