324 PRACTICAL BOTANY 



its early stages with that of homosporous leptosporangiate Ferns : 

 it is only in the later stages, after the division of the spore-mother- 

 cells, that the distinction appears between male and female 

 sporangia. 



By keeping mature sporocarps moist during the autumn, their 

 rupture by four valves may be observed, and the extrusion of 

 the macro- and microspores embedded in a swollen mass of 

 mucilage : in this the spores germinate, but it disappears after a 

 time. Cultures should be kept, and examined at intervals. 



Longitudinal sections should be cut through the macrospores 

 after the mucilaginous mass has disappeared : in these the 

 rudimentary female prothallium maybe found at the apex of the 

 spore, bearing an archegonium : in others, taken later, young 

 embryos in various stages of development may be found and 

 examined. Compare these with those of other Ferns. 



Observations may also be made with advantage on the sporo- 

 carp of Marsilea, which, though differing in form from that of 

 faj corresponds to it in its essential points. 



