276 EXPLANATION OF THE PLATES. 



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

 spores, are all developed out of the germinal corpuscle, which 

 occupied its central cavity. 



Fig. 11. Section of the germinating spore of Pilulcvria (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 fern- 

 spore. 



Fig. 13. Prothallium or cellular outgrowth from the spore 

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

 c, 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. 



