﻿J 54 



REPRODUCTIVE STRUCTURES. 



produce a very ornate appearance. Especially to be noted among the mass of syn- 

 angia as thus distributed are the transverse sections of the successively cut pairs 

 of slender sporophylls, figure 73, iv. In the succeeding section, cut well above the 

 summit of the ovulate cone, and shown on plate xxxvi, photograph 2a, the rela- 

 tions just noted do not change, except that all the rachides are free, though, as 

 before, lying closely appressed and occupying all the available space to the extent 

 even of more or less remodeling of adjacent parts, or formation of appression faces. 

 Obviously the great regularity of position and preservation in entirety of all 

 these parts enables us to determine at once not only the form, but the attachment 

 and number of the sporophylls, as well as the number and insertion of the synangia 

 borne by each, thus making our conception of the form of the individual fronds 

 and organization of the bisporangiate axis complete in every respect. In the first 

 place, the successive transverse sections show the outline of each rachis throughout 

 its entire length. The lower portion, after rising free from the disk, is triangularly 



Fig. 78. — Zamia gigas. 



" Restoration of half of carpeliary disk, showing vascular exterior, superficial parenchyma, ovules in situ, and supposed abortive ovules." 

 Enlarged about one-half. From Williamson. Trans. Linn. Soc. Vol. XXVI. 1870. Pis. 52, 53. For comparison with fig. 79. 



prismatic, while the tip is at first laterally compressed and then expanded, this 

 peculiar shape being chiefly due to the space arrangement of the floral parts and to 

 the flattened ventral faces of the rachides which lie edge to edge, so as completely to 

 inclose the central and conical ovulate axis, in the absolutely compact order so 

 clearly shown in the restoration figure 70 and the companion sketch to the same 

 (fig. 88). 



The fact that sporophylls or filiciform pinnules are usually cut through their 

 full length in longitudinal sections and are never seen to branch, and that in the 

 transverse sections the}- are always cut in obliquely set pairs, shows that the frond 

 is once-pinnate, with the pinnules alternating and folded back straight and distich- 

 ously, exactly as are the pinnules of the similarly once-deflexed rachis of the once- 

 pinnate young fronds of Zamia floridana. The fact that in longitudinal sections 

 the synangia appear in rows, oftener unattached than attached, while in transverse 



