IS 



HEREDITY AND EVOLUTION IN PLANTS 



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

 b, early stage, showing protonema (pr.), and first rhizoid (rli) ; r, d, c, /, 

 successive stages in the development of the prothallus. 



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

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

 C. Ferguson.) 



