The Origin of Land Plants 97 



the former being enclosed in the meshes of a net- 

 like complex of sterile cells. This segregation of the 

 sporogenous cells into groups is probably the first 

 hint of the definite spore-bearing organs or spo- 

 rangia, which are characteristic of the ferns. Were 

 the sporophyte of Anthoceros to develop a true root, 

 i.e., to come into direct contact with the source of 

 water supply and soil constituents, the sporophyte 

 would be rendered quite independent, since the 

 highly developed photosynthetic apparatus is ample 

 to provide for the assimilation of CO 2 . 



Whether or not the Anthocerotes are considered 

 to be directly related to the ancestors of the Pterido- 

 phytes, or ferns, there is no question that both in 

 the character of the reproductive organs and that of 

 the sporophyte, they resemble more nearly the Pteri- 

 dophytes than do any other liverworts. 



Sporophyte First Becomes Independent in the 

 Ferns. Although in Anthoceros and the higher 

 mosses, the sporophyte attains a large measure of 

 independence, it never becomes entirely independent 

 of the gametophyte upon which it must draw for its 

 water supply, owing to the failure to make direct 

 connection with the earth. In the second division 

 of the Archegoniates, on the other hand, the 

 Pteridophytes or Ferns, the young sporophyte at an 

 early period develops a true root (Fig. n, A, r), 

 which pierces the tissues of the gametophyte and 

 grows downward into the ground, so that the young 

 sporophyte henceforward absorbs its water supply 



