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354 BOTANICAL GAZETTE [NOVEMBER 
The ability of this form to occupy its peculiarly trying habitat, 
with its abundant salt, frequent and prolonged immersion, and 
shifting substratum are amply explained by its adaptive struc- 
tures above considered, notably its xerophytic anatomy combined 
with a very perfect transpiration-regulating mechanism, its 
capacity for copious air storage, and its system of interlacing, 
firmly anchored rootstocks, to which may be added the probable 
specific power of its root-hairs to resist plasmolysis by salt water. 
It is of course because no other plant possesses anywhere near 
the same combination of qualities that it reigns supreme, without 
competitor or companion, in its own peculiar habitat. There 
are forms which can stand as much immersion, and forms 
which can stand as much salt, but no forms which can stand 
a combination of these two conditions in so extreme a 
degree. 
Like all other associations it tends to spread outside its own 
typical habitat. With the slow, irresistible, phalanx-like advance 
of its rootstocks, it easily enters the habitat of the Salicornetum, 
and utterly defeats and destroys that association ; it then advan- 
ces upon the Staticetum against the margin of which it can pre- 
vail, to some extent, but ultimately it is overcome by that 
association, excepting where depressions with their salter soil 
enable colonies of it to thrive. In the lakes it is finally over- 
come by the broadleaf. 
water, made solutions of all strengths from 10% to 90%. I gathered all the seeds of 
halophytes I could procure myself or by aid of a correspondent at Sackville (Mr. F. A 
Dixon), and started them with fresh water in Zurich germinators. As soon as root- 
hairs appeared I tested them with the various solutions, and noted for each kind the 
solution which just initiated plasmolysis. I-found a close correspondence between 
the halophilism of the plant and the power of its root-hairs to resist eee a the 
details being given dak oF various _—* in the Bowes. Ri This shows that’ 
the power of the plant with and probably ‘acceuient 
upon the ability e the root-hairs to resist sans ysis. This power has of course 
n gradually acquired, but what its physical basis is I do not know; though we shall 
probably find that substances aris cally equivalent to the salt of the sea-water have 
been formed in the sap of the hairs. In several cases (Hordeum, Couch) it was notice- 
jelly-like caps to the young roots, seemingly an adaptation to slower water-entrance. 
The study of the roots of these halophytes will give interesting results. 
