119 
breaking away, and by this and other means, sections of the root- 
stock finally reach the beach and are worn by the waves until 
the tough roots, that have their origin particularly in the tubers, 
are reduced to spine-like processes. 
Smilax glauca not only grows on sandy bluffs and dunes, but 
also in low land, that for a portion of the year is quite wet. 
These conditions produce their effect upon the plants, and those 
occupying the dry and sandy places are not, in every particular, 
like those that have grown on moister ground. There is not 
only the usual difference between plants that grow on dry 
places and on damp ones, namely: a difference in depth of root, 
but there is also a variation of growth, which is evidently useful 
and adapted to environment. 
The rhizomas of Smilax glauca are always tuberiferous, the 
tubers being occasionally connected to the rootstock at one end 
only, but generally they are swellings, sometimes of single nodes . 
and sometimes of several nodes coalesced, that form along the 
rhizoma itself, and are centers of collected nourishment, Many 
of the upright leaf-bearing branches, as well as the main and more ~ 
robust roots, are connected with these tubers, and when the tub- 
ers consist of several coalesced nodes, the roots grow from them — 
in circles of some regularity, but the coalescence is also plainly 
seen in some instances, without the aid of the accompanying 
roots. 
The change of growth with change of condition, mentioned 
above, is especially noticeable in these tubers, which appear to 
be more numerous on plants growing on dry, sandy stations, to 
have a greater number of roots starting from them and fewer — 
from the internodal spaces, and also to be often of larger size, 
than on plants occupying moister situations. This is easily ex- 
plained, for they have more need of stored moisture and nourish- _ 
ment than those of the low, wet ground. Also in these latter 
- plants the spaces between the nodes are greater than in those 
occupying the dunes. Ws. T. DAVIS. 
