SELAGINELLA SP. 125 



a. The cells formed just within the spore wall and that 

 separate it from: 



b. A centrally placed cell, which later divides, thus form- 

 ing the mother-cells that in turn form the sperms. 1 



c. Draw. 



2. The female gametophyte. By studying a section of a 

 germinating megaspore observe: 



a. The space enclosed by the megaspore wall partially 

 filled at its apical end by female gametophyte tissue. 



b. The basal part containing vacuoles, or granular food 

 substances, or both. 



c. The archegonia developed on the part of the gameto- 

 phyte exposed by the rupture of the spore wall. 



d. Draw. 



In some sections it may be that eggs have been fertilized 

 and stages in the development of the sporophyte embryo can 

 be seen. If so, note the following stages: 



e. The first division-wall of the oospore. 



/. The elongation of the outermost of the two cells 

 formed by the first division of the oospore. This 

 elongated cell is the suspensor and serves to push 

 the other cell (embryo-cell) into the female gameto- 

 phyte that nourishes the embyro as it develops. 



g. A specimen in which embryonic leaves, stem, and root 

 can be distinguished. 



h. A specimen in which the young sporophyte plant is 

 emerging through the megaspore wall. 



i. Draw, illustrating the various stages seen. 



1 With Marsilia it is comparatively easy to obtain living sperms by 

 placing the dried sporocarps in water. After a day or two the micro- 

 sporangia and spores will be pushed out of the sporocarp and the sperms 

 will escape from the male gametophytes produced within the micro- 

 spore walls. 



