Bower.—Studies in the Phytogeny of the Filicales. 529 
plate xxv. 
Fig. 2. Drawing by Mr. J. M. Thompson of a rhizome with the superficial hairs removed, so 
as to expose the successive leaf-bases, which are numbered i to /.-viii, and the lateral axes which 
spring from their bases (ax. i, to ax. iv). But the leaves iii, vi, vii, viii have no associated axes. 
The leaf-arrangement is alternate, and the shoot is seen from the side facing away from the support, 
x 2. 
Fig. 16. Transverse section of a fertile leaf of Platycerium Willinkii, Moore, showing strands 
belonging to the two vascular systems: the strand nearer to the upper surface belongs to the main 
system of the lamina, that nearer the lower surface is a receptacular strand, x ioo. 
Fig. 17, a-e. Stages in the development of the sporangium of Cheiropleuria. a, b, c show the 
alternate cleavages of the primordium to form two rows of cells of the stalk: d shows the formation 
of the cap-cell: e shows the beginning of formation of the tapetum: f shows the tapetum com¬ 
plete, as two layers surrounding the sporogenous cell, x 250. 
Fig. 18, a-c. Stages in development of the sporangium of Dipteris. a shows a young sorus of 
D. Lobbiana, bearing two hairs, and two sporangia. The receptacular tracheides are closely below 
the surface, and are of the large storage type, b shows a sporangium of D. conjugata seen from 
the side facing one of the rows of segments, and demonstrating how each segment divides into two 
cells, which together with the results of division of the segments of the other row form the four rows 
of cells of the sporangial stalk, c represents transverse sections of similar sporangia of D. conjugata , 
showing some stalks—the younger, with only two cells; others, the older, with four cells. In one 
sporangium there are only three, one segment having divided and the other not. x 325. 
