254 



LIFE HISTORY OF BRYOPHYTA 



ing growth of the gametospore. This postponement in the for- 

 mation of the spore mother cells, owing to the larger and larger 

 growth of the gametospore, will steadily progress in the following 

 studies. 



These simple liverworts, like Ricciocarpus, show very clearly 

 two phases or generations in their life history. The thallose 

 plant is the gametophyte or sexual generation because it bears 

 sexual cells or gametes. The capsule is the sporophyte or asex- 



Fig. 185. Diagram of the life history of Ricciocarpus. The upper por- 

 tion of the figure represents the sexual generation and the lower portion, 

 the asexual. The former generation begins with the formation of the 

 spores, sp, from the mother-cell and ends with the formation of the gam- 

 etes, g. The asexual generation begins with the gametospore, gm, and 

 ends with the spore mother cells, sin. 



ual generation because it can only produce spores. The gameto- 

 phyte begins with -the spore and ends with the formation of the 

 gametes. The sporophyte begins with the gametospore and ends 

 with the division of the spore mother cell (Fig. 185). It may 

 appear to An now as strange to regard the few cells of the cap- 

 sule^^ie majority of which become spore mother cells, as a plant. 

 IWit^| shall directly see this microscopic plant assuming larger 

 propolftons as a result of its better nourishment and the stimuli 

 to which it is exposed. It will form a larger and larger number 

 of cells and the spore mother cells will not appear until late in its 

 growth and they will be confined to definite regions and only con- 

 stitute a small part of it. We now call the gametophyte the plant 

 because it is many times larger than the sporophyte, but we will 



