ABSTRACT
Mosses exhibit a concrete periodicity in their growth pattern by perceiving stimuli in the environment. They show manifestation of gametophytic and sporophytic phases. Regeneration products of varying nature can be obtained from the same organ, such as the sporophyte. F. V. Wettstein had predicted that hybrids produced by reciprocal crosses among the members of Funariaceae would be excellent materials for understanding developmental physiology in mosses. On the basal medium supplemented with 2% sucrose the callus cells of Physcomitrium pyriforme differentiated only partially. The remainder turned brown and became quiescent. Such callus masses, when subcultured on fresh medium of the same composition, turned green and differentiated readily after showing slight multiplication. The callus was also subcultured on the basal medium devoid of sucrose. In high light intensity the differentiation was mainly gametophytic, and in low light intensity the callus remained largely undifferentiated except for the appearance of some protonemal filaments.
