SPORES AND THALLIDIA. 



11 



Fig. 189.— Ferns. 



1 Nephrolepis Duffl,. "^ Tnchomanes Lyelli. s Sorus of the same Fern with cup-shaped investment seen in longitudinal section. 

 ^ Rhipidopteris peltata. ^ Polypodium serpens. ^ Pinna of Qleichenvx, alpina. "^ Schizcea fistulosa, 8 Botrychiwm lanceo- 

 latum. 9 Under side of a pinna of Oleichenia alpina, ; in the two upper cavities the sporangia are covered by leaflets, in 

 the under ones they are exposed, lo^ n Pinna of Cyatkea elegans. is Longitudinal section through a Sorus and Cup of 

 Cyathea. i^ Sporangium of Cyathea. i* Sporangium of Polypodium. is Sporangium of Sckizcea. is Under side of the 

 Prothallium of Spleenwort. \ ^, *, s, s, "J, 8 natural size ; », s, lo, n, 12, is, i*, is, is magnified from 5 to 20 times. 



