276 EXPLANATION OF THE PLATES. 



calyptra or wliile the fruit-stalk, capsule, lid, and contained 

 six>res, are all developed out of the germinal corpuscle, which 

 occupied its central cavity. 



Fig. 11. — Section of the germinating spore of Pilularia (after 

 Hofmeister). At the lower part of the figure are seen the nu- 

 cleus and two coats of the spore. The pyramidal body at the top 

 is the prothallium, a structure of later growth, here represented 

 as protruding through the micropyle. The section shows an 

 archegonial cavity in its interior — (pp. 57, 183). 



Fig. 12 and 13 (after Suminski) illustrate the process of ger- 

 mination in Ferns — (p. 52, 183). Fig. 12. — ^A tetrahedral fem- 

 sj)ore. 



Fig. 13. — Prothallium or cellular outgrowth from the spore 

 (Pteris serrulata). a, remains of the spore ; 6, radical filaments ; 

 e, antheridial cells containing cellules with ciliated filaments in 

 their interior ; d, archegonia. 



Fig. 14. Shows the connection of a young Fern (Pteris 

 paleacea) developed from the archegonial corpuscule, with its 

 prothallial matrix. 



