SPORES AND THALLIDIA. 



11 



JFig. 189.— Fems. 



NephroUpis Duffi. ^ Trichoma'ms I/yelli. s Sorus of the same Fern with cup-shaped investment seen in longitudinal section. 

 ^ Bhvpid(ypteris pdtata. * Polypodium serpejxs. ^pinna of Gleiehenia alpina. 7 Schizceajistulosa. s Botrychium lanceo- 

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

 the under ones they are exposed, lo, n Pinna of Cyaikea elegans. 12 Longitudinal section through a Soma and Cup of 

 Cyathea. is Sporangium of Cyathea. 1* Sporangium of Polypodiwm. i* Sporangixim of Schizcea. 18 Under side of the 

 Prothallium of Spleenwort. 1, 2^ i^ s^ 6^ 7^ a natural size ; s, 9, 10^ 11, 12. is. 14^ 15^ le magnified from 6 to 20 times. 



