GAMETOPHYTE 



433 



swimming sperms {Fig. 385). The chimnoy-shaped archegonia 

 are near the notch of the prothallus, and the globular anther- 

 idia are in the region of the rhizoids. In some Ferns the male 

 and female sex organs are on different gametophytes. 



The sperms are active swimmers and reach the egg by swim- 

 ming down the neck of the archegonium which, like the arche- 

 gonia of Bryophytes, opens at the top when the egg is ready for 

 fertilization. From the neck of the archegonium, a substance is 

 also discharged, which chemically attracts the sperms. 



Fig. 387. — A diagram of the life cycle of a Fern. A, sporophyte bearing 

 sori in which the sporangia occur. B, a gametophyte, a product of a spore 

 and the generation bearing the gametes, the sperms of which are shown 

 passing from the antheridia to the archegonia. C, gametophyte bearing a 

 sporophyte, which soon becomes independent andHike the one at A . 



The fertiUzed egg immediately grows into a sporophyte, which 

 lives on the gametophyte only until it has roots and leaves 

 sufficiently developed to support itself {Fig. 386). After the 

 sporophyte reaches maturity, sori are developed and the life cycle 

 is completed {Fig. 387) . Among a group of gametophytes one 

 usually finds sporophytes in various stages of development and 

 greenhouse attendants sometimes collect and pot the j^oung 

 sporophytes growing in unfavorable places, so that they mature 

 and thereby increase their stock of Ferns. Usually, however, 



