3i8 NATURE OF THE GAMETOPHYTE 



tophyte and in origin and appearance are rather suggestive of 

 Anthoceros. The antheridia consist of a number of mother cells 

 quite buried in the tissues of the thallus, being covered by one 

 or two layers of cells which are destroyed or break open when 

 the male gametes are mature (Fig. 218, C). These gametes are 

 quite different from any yet seen, being spirally coiled and pro- 

 vided with numerous cilia (Fig. 218, D). The archegonia are 

 similar to those noted in Anthoceros, consisting of a rather short 

 neck with two central canal cells and a swollen base sunken in 

 the tissues of the gametophyte (Fig. 218, £). The female gamete 

 is formed at the base of the canal cells which finally become 

 mucilaginous and thus form an open passage-way for the entrance 

 of the male gametes as soon as the lip cells have opened. It has 

 been shown in the common ferns that malic acid is present in 

 this mucilaginous substance which strongly attracts the male 

 gametes so that they crowd into the canal, often completely chok- 

 ing it. So we see that the gametophyte of this fern (though 

 differing in form) is essentially of the same character as in the 

 Bryophyta, its subterranean character and absence of chlorophyll 

 being due to its association with fungi. It should be stated that 

 lobes are produced from the end of the tuberous gametophyte 

 of one of the species which become green on reaching the surface 

 of the soil and in a closely allied order or tropical ferns, the 

 sexual generation is normally a green thallus strikingly like some 

 of the simpler Jungermaniales. 



(&) The Germination of the Gametospore. — The early develop- 

 ment of the sporophyte resembles Anthoceros in many respects. 

 The gametospore divides into two cells (Fig. 218, F), from the 

 lower of which a large foot is formed, and from the upper cell 

 the short stem and root arise. Later, the first leaf or cotyledon 

 is formed from the stem. This development of the sporophyte 

 goes on very slowly within the archegonium where it lives as a 

 parasite for a long time. Eventually the root ruptures the arche- 

 gonium or calyptra and comes in contact with the soil. The 

 cotyledon now grows upward and makes its appearance above 

 the ground as the first green leaf (Fig. 218, G). The sporophyte 

 thus becomes a self-supporting plant, although it probably re- 



