494 A TEXTBOOK OF THEORETICAL BOTANY 



The prothallus is a self-supporting organism whose cells contain numerous 

 chloroplasts and are able to perform photosynthesis, and whose rhizoids 

 can obtain mineral matter from the soil. The prothallus represents the 



I 



Fig. 483. — Dryopteris filix-mas. Germination of the spore and early stages in the 

 development of the prothallus showing diflferentiation of the apical cell and 

 beginnings of lateral expansion. {After Kny.) 



gametophyte generation of the Fern, so called because the sex organs are 

 developed at this stage. 



Hidden on the inconspicuous prothallus the sex organs of the Fern 

 were for long unknown. This gave rise to the term cryptogam (or " hidden 

 marriage "), which was applied generally to all the flowerless plants. The 

 sexual reproduction of the Fern was discovered by Suminski in 1848, and 



