Dui'inv; i.iiic dc;Vijlopr:ijnt of Uie b.'sicoiiic ultirni-.-t 

 mar^^inal cell the iicroscopic one splits, nGiiLill;; by one 

 transverse anticline (Figs. HG -08, 64), into two cells, 

 one of v.rliich lielps to I'orm the outer layer oJ the lateral 

 indusii¥n in its ovm segment, v/Mle he otlier does I he same 

 for the sorus of the next yo imgor segment ( o.ind.. Figs. 

 5o, 0) » 



Retm-ning now to the development of the five c&lls 

 fonned in the basiscopic marginal cell as seen in a cross 

 section of the capsule, v/e find that at first it is very 

 similcir for all, and we may take for further study, sections 

 in the plane of the macrosponingiim moth.er cell. This 

 is seen to elongate radially and then to divide by a peri- 

 clino (Fig. 02), th.en by furtiier grov/th tmd division of 

 both of the cells thus formed ( ma-sp.m.c. Fig. 5S) there 

 arises a rov; of seven or eight cells reaching f:-o:a about tlie 

 center of the capsule nearly to ':he ventral surface (Fig. 

 54), all of v/hich are separated by the soral cavity from 

 the cells of the inner layer of the indusium arising in 

 section V • From i-ne increase in size of both of the 

 cells fonned from the marginal cell by the first pori- 

 cline, from the occur/'ence of nuclear spindles in both, 

 and from their relation to the surrounding cells, there 

 can be no doubt that both diviuo i-u/uiier lum rivc rise to 



