FACTORS OF INCREASE 
Fic. 64. 
a, 6, ¢, 7, R=Gleichenia flabellata, Br. d, e, f=Gl. circinata, Sw. g, h, i=Ge. 
dichotoma, Willd. a, 8, c, ad, show young sori with sporangia marginal. g shows a 
similar condition in GZ adichotoma, but in 4 and z the vacant middle space is occupied by 
young sporangia. @-2%200. 7, &X 100. 
Fic. 65. 
A, B, Dennstacdtia apiifolia, Hook. A shows the regular basipetal succession of 
sporangia characteristic of the Gradate. C, D, Dennstaedtia rubiginosa, Kaulf. D 
shows irregularity in the succession. X 100. 
