LIVERWORTS 



399 



of the archegonia hang down. This stalked structure 

 with the finger-like branches is an archegoniophore. Some 

 liverworts do not have archegoniophores ; their archegonia 

 are embedded in the thallus with the 

 necks up and open at the top. As 

 you have already guessed, it is down 

 the neck that the sperms pass to 

 the egg. 



The sperms are borne in organs 

 called antheridia, a term which you 

 used to describe the sperm-bearing 

 organs of thallophytes. The anthe- 

 ridia of liverworts produce great 

 numbers of sperms. (See Figure 

 197) All the sperms of bryophytes 

 are very small and bear two cilia. 

 In the picture of Marchantia {Figure 

 195) you have noticed those branches 

 whose flat tops are scalloped at the 

 margin. These are antheridiophores 

 and the antheridia are found em- 

 bedded in their flat tops. They 

 open on the upper surface. An- 

 theridia are borne in other ways by 

 other liverworts. 



Perhaps you have already wondered how fertilization 

 is accomplished in Marchantia. You know that in some 

 way the sperms must reach the eggs or else all these struc- 

 tures that we have been describing are of no use to the 

 plant. Sperms are not like pollen ; they are not blown by 

 wind or carried by insects. In order to move they need 

 water; they swim actively by means of their moving 



A 



Fig. 196. — Archegonia of 

 Marchantia. A, a mature 

 archegonium, ready for fer- 

 tilization. B, young stage, 

 showing the row of central 

 cells of which the lowest 

 becomes the egg. 



