326 BOTANICAL GAZETTE [Novewsen 
The stipe—Very young stipe areas in Lessonia are much flat- 
tened, being morphologically nothing more than proximal areas 
of the lamina. As the plant grows, however, the region of the — 
stipe undergoes a kind of secondary thickening, resulting in a 
ringed structure; and, by the greater thickness of the ring on 
one or both sides of the original flattened organ than over the — 
edges, the whole stem changes from a flattened to a cylindrical : 
body. The pith in all such cylindrical stems, even when they : 
are very large, persists in its original thin and flattened structure, — 
and does not appear in the form of cylindrical medulla as it does — 
in Nereocystis. The pith is very often excentrically placed, and 
the number of rings of growth on one side may apparently be . 
twice as many as on the other. 
I have not found anywhere in the literature an adequate 
account of the anatomical basis of the phenomena which have 
been known and commented upon since the first discovery of ? 
Lessoniez ; and in the plates accompanying this paper an ©P© 
cial effort has been made to indicate the occasion for the ringed 
appearance so characteristic of the Lessonia stipe. It has long : 
been suspected that the rings are in no sense annual ring 
has been believed that they are connected with the developmes : 
of the tufts of leaves in such a way that for each cycle of — - 
there should be an additional ring of tissue developed ag : 
older portions of the stipe. No doubt this view i 
from the exceedingly rapid growth of these gigantic alge 
altogether reasonable to suppose that several rings ™g™ 
produced in a single season. 
tings of growth were apparent on one side © 
three upon the other. The pith itself looks almost , 
same in vertical section as in cross section, anid 15 ™ pedde 
an anastomosing web of loosely interlaced filaments pi : 
in gelatin and filled with reserve food materials. The pi 
