1908] 



BARNES & LAND—CUPULE OF MARCHANTIA 



407 



gemmiparous cells, so that each basal cell ultimately becomes the 

 center of a group. 



As the primordium of a cupule grows older, the number of gemmip- 

 arous cells forming its floor is increased by longitudinal (anticlinal) 

 divisions (/, figs. 8, p). The new floor cells so produced grow into 



Fig. 11 Fig. 12 



Figs, ii, 12. — Further development of gemma cell (now triple) 



and rim (w). 



papillae and soon produce gemma cells. Thus the gemmiparous 

 area is increased in two ways: by the anticlinal division of the prim- 

 ordial cells, and by a similar division of basal cells that have borne 

 or are bearing gemmae. The tissues adjacent grow rapidly, leaving 

 the floor of the cupule soon far below the general surface (fig. 12), 

 and the rim continues to outgrow the developing gemmae, which are 

 embedded in mucus. The antero-posterior diameter of the young 



