96 Plant Life and Evolution 



long-continued growth, a very large bulbous foot is 

 developed, and, although this has no direct connec- 

 tion with the earth, there may sometimes be seen 

 to be an extraordinary development of roots from 

 the under side of the gametophyte immediately be- 

 low it, and this unusual development of the roots 

 is obviously induced by the protracted growth of 

 the sporophyte, and its increased need for a greater 

 supply of water. The large sporophyte becomes 

 almost independent of the gametophyte, but not 

 wholly so, as it is still dependent upon it for its 

 supply of water. The upper part of the sporophyte 

 shows a well-developed epidermis, perforated by 

 numerous stomata, exactly like those of the higher 

 plants. Beneath the epidermis are several layers of 

 green cells with intercellular spaces communicating 

 with the openings of the stomata, and this green tis- 

 sue, both in structure and function, closely resembles 

 the mesophyll or green tissue of an ordinary leaf. 



The axis of the sporophyte is occupied by a 

 strand of much elongated cells, which are presuma- 

 bly more or less active agents in the conduction of 

 water, and possibly may be regarded as the equiva- 

 lent of the vascular bundle, which occupies a similar 

 position in the young organs of the sporophyte in 

 the so-called " vascular " plants. In Anthoceros, 

 the spore-producing tissue is reduced to a single 

 layer of cells situated below the green assimilative 

 tissue. There is sometimes a more or less complete 

 separation of this tissue into fertile and sterile areas, 



