LIFE HISTORY OF A LIVERWORT 



2I 3 



not from epidermal cells as in ferns, but each one from a 

 single cell just underneath the epidermis (subepidermal), 



FIG. 156. Anthoceros Icevis, showing the lobed thallus of the gameto- 

 phyte, bearing several upright sporogonia in various stages of develop- 

 ment. At the right and left sporogonia dehiscing, and scattering the 

 spores. Note the slender, thread-like columellas, and the lack of differ- 

 entiation of the sporogonium into seta and capsule. The sheath (calyp- 

 tra) at the base of the sporogonium is formed chiefly from the vegetative 

 tissues of the gametophyte, and only to a slight extent by the walls of the 

 archegonium. 



FIG. 157. Anthoceros Pearsoni. Longitudinal section through a well- 

 developed, glandular thickening, in which are embedded a number of 

 antheridia. X 53. (After M. A. Howe.) 



near the dorsal surface. They remain imbedded in the 

 surrounding tissue until mature, closely resembling, in 



