Minnesota Plant Life. 



167 



backbone of the centipede-shaped affair has, however, the ap- 

 pearance of clear jelly and is enormously swollen by the ab- 

 sorption of water. The "legs" of the centipede, twelve to 

 eighteen in number on each side, are yellowish and upon close 

 examination appear to be elongated transparent sacs in each 

 of which a number of pearly yellow bodies of generally oval 



Fig. 58. The interrupted fern (in background) and shield-ferns (in foreground). After 



photograph tay Williams. 



shape are situated. These bodies are spore-cases, some of 

 them containing sixty four small-spores and others containing 

 one large-spore, each. As in quillworts and smaller club- 

 mosses, the small-spores produce little reduced males while the 

 large -spores develop females. The egg of the female, never 

 more than one to the plant, segments, after fecundation, into 



