LIVER IVOR TS : MARCHANTIA. 



151 



This shows us an increase in the size and complex structure of 

 this new phase of the plant, the sporophyte. This is one of the 

 very interesting things which we have to note as we go on in the 

 study of the higher plants. 



Fig. 184. 

 Marchantia polymorpha, archegonium at the left with egg ; archegonium at the right with 

 young sporogonium ; /, curtain which hangs down around the archegonia ; £, egg ; v } venter 

 of archegonium ; n, neck of archegonium ; sp, young spoiogonium. 



323. Sporophyte dependent on the gametophyte for its nutri- 

 ment. — We thus see that at no time during the development of the 

 sporogonium is it independent from the gametophyte. This new 

 phase of plants then, the sporophyte, has not yet become an in- 

 dependent plant, but must rely on the earlier phase for sustenance. 



324. Development of the sporogonium. — It will be interesting to note 

 briefly how the development of the marchantia sporogonium diners from that 

 of riccia. The first division of the fertilized egg is the same as in riccia, that 

 is a wall which runs crosswise of the axis of the archegonium divides it 

 into two cells. In marchantia the cell at the base develops the stalk, so 

 that here there is a radical difference. The outer cell forms the capsule. 

 But here after the wall is formed the inner tissue does not all go to make 

 spores, as is the case with riccia. But some of it forms the elaters. While 

 in riccia only the outside layer of cells of the sporogonium remained sterile, 

 in marchantia the basal half of the egg remains completely sterile and 



