SELAGINELLA 151 



(ft) Carefully count and record the number of 

 megaspores in one megasporangium. Is the 

 number always even? 



(i) Carefully observe the megaspores under a high 

 power, and endeavor to account for their shape. 



(;) Make drawings to show all points observed 

 under , 2, (a)-(h). 



(k) Make a study of the microsporophylls, micro- 

 sporangia, and microspores, similar to those 

 just made under E, 2, (a)-(i). 



(/) The number of microscopes is too large to 

 permit of their being readily counted. Sug- 

 gest any advantage to the plant in such a large 

 number of microspores. Explain the cause of 

 the difference in size. Suggest an advantage 

 to the plant in the large size of the megaspore. 

 (m) Mount megaspores and microspores together 

 and make drawings to show their relative 

 sizes. 



(n) Make drawings to illustrate all points observed 

 under E, 2, (k). 



F. Sexual Reproduction: 



i. The gametophytes of Selaginella are not readily 

 obtained in suitable form for study. If prepared 

 slides are available, studies may be made of: 



(a) Archegonia and eggs. 



(b) Antheridia and sperms. 



G. Comparisons: 



1. Compare the relative prominence of the gameto- 

 phyte and sporophyte in Selaginella. Compare, 

 in this respect with all the forms previously studied. 



2. Compare the method of reproduction by spores in 

 Selaginella with that in the forms previously 

 studied. Why should Selaginella be considered 



