FACTORS OF INCREASE 



123 



FIG. 64. 



, b, c, j, k Gleichenia ftabellata, Br. d, e, f=Gl. circinata, Sw. g, h, i=GL 

 dtchotoma, Willd. a, i>, c, d, show young sori with sporangia marginal, g shows a 

 similar condition in Gl. dichotoma, but in h and i the vacant middle space is occupied by 

 young sporangia. a-/X2oo. /, xioo. 



FIG. 65. 



A , By Dennstaedtia apiifolia, Hook. A shows the regular basipetal succession of 

 sporangia characteristic of the Gradata;. C, D, Dennstaedtia rubiginosa, Kaulf. D 

 shows irregularity in the succession. X TOO. 



