LIFE HISTORY OF A LIVERWORT 
213 
not from epidermal cells as in ferns, but each one from a 
single cell just underneath the epidermis (subepidermal), 
FIG. 156. Anthoceros Iceyis, 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 
