On Gymnospermous Seeds. 149 
The annexed diagram (text Fig. 5 ) represents a transverse 
section across the middle of the seed based on the information 
given by Brongniart and Renault. The apprehension of the 
complex relations of the parts has become a matter of no little 
difficulty owing to the conflicting nature of the original accounts. 
Particular reliance has been placed on Brongniart’s plate xviii, figs. 
1 and 2, and Renault’s plate lxxxiii., fig. 5 . The diagram is, how 
ever, an interpretation based on data lacking somewhat in 
completeness. The outer dark ring is the exotesta which seems 
Text figure 5 . 
Transverse section of Pachytesta, adapted from published 
figures of Brongniart and Renault. The darker outer zone (ext.) is 
the exotesta, with sclerized external and internal bauds (black); 
aid.t. endotesta with longitudinal grooves at g; sclerotic 
radial plate of exotesta; rp . 1 and rp . 2 ditto split; (n) nucellus 
with ridges (nr.) which engage with the grooves of endotesta (g); 
ps., protliallial space; v d and v . 2 outer and inner series of bundles 
of the exotesta; v 3 bundles in the micellar wall ( x 2). 
to have consisted of a spongy pitted tissue, limited within and 
without (the thick dark edges) by sclerotic layers—the whole being 
perhaps equivalent to sarcotesta and sclerotesta in other cases. At 
three spots symmetrically placed the sclerotic tissue forms radial 
plates cutting the testa into three arcs. These arcs separate ulti¬ 
mately into valves by the rupture of these radial plates as at rp} 
