50 



BOTANY AND PHARMACOGNOSY. 



new plant. With the formation and dispersal of the spores the 

 work of this generation terminates, and this phase is called the 

 sporophyte or asexual generation, from the fact that it produces 

 spores. 



Having thus followed the stages of development in the life- 

 history of a m6ss, we see that it is composed of the following 



Pig. 29. Dichotomously branching thallus of the common liverwort {Marchanlia 

 polymorpha) showing near some of the margins the cup-like depressions in which gemmae 

 are borne (c), and several archegoniophores (a). 



parts: (i) The alga-like protonema; (2) the leafy branch which 

 gives rise to an oospore (sexual spore), and (3) the sporogonium 

 which produces asexual spores. The leafy branch is sometimes 

 spoken of as the gametophore (gamete-bearer), and it and the 

 protonema together constitute the gametophyte or sexual gen- 

 eration, while the sporogonium represents the sporophyte or 

 asexual generation. 



