i8 



HEREDITY AND EVOLUTION IN PLANTS 



FIG. 19. Germination of the spores of a fern, c, Before germination; 

 6, early stage, showing protonema (pr.), and first rhizoid (rti); c, d, e, f, 

 successive stages in the development of the prothallus. 



FIG. 20. Prothallus of a fern. Archegonia on the (central) cushion, 

 near the notch; antheridia among the rhizoids, below. (After Margaret 

 C. Ferguson.) 



