PH HOPHYCEX 43 
parts which extorts the use of such terms as stem, 
leaf, and root, however unconventional such an 
employment of them may appear from the point of 
view of formal morphology. It has been pointed out, 
for example, that the transition from the lower to 
the upper leaves of certain species of Sargassum 
@ 
——— 
SS 
ee = 
—— 
ss 
i 
\ 
i | 
Fic. 3.—a, Cocenphora Langsdorfii (reduced) ; b, transverse section of stem ; 
¢, longit. section of same passing through base of leaf. 6 and ¢ much magnified. 
(After A. L. Smith, in Phyc, Mem.) 
furnishes a parallel appearance to the familiar 
change of form to be observed in the leaves of 
flowering plants. When such differentiation is 
allied with the production of special receptacular 
or fruiting branches, arising from the base of the 
