SPORES AND THALLIDIA. 



11 



Kig. 189.— Ferns. 



Mephrnlepis Dufi. ^ Trickomancs Lyelli. 3 Sorus of the same Fern with cup-shaped investment seen in longitudinal section. 

 * Rhipidopteris pcltata. ^ Polypodium serpens. ^ Pinna of Gleichenia alpina. ' Schizcea Jistulosa. 8 BotrycUium lanceo- 

 latum. 3 Under side of a pinna of Gleichenia alpina; in the two upper cavities the sporangia are covered by leaflets, in 

 the under ones tliey are exposed. ^^, i' Pinna of Cyathea elegans. 12 Longitudinal section tlirough a Sorus and Cup of 

 Oyatkea. ^ Sporangium of Cyathea. 1* Sporangium of Polypodium. is Sporangium of Schizcea. I8 Under side of the 

 Prothalliuni of Spleeuwort. 1, 2, *, s, ^, 7, s natural size ; 3, 9, 10, 11, i^. 13. u^ is^ le magnified from 5 to 20 times, 



