a? a 
1903] VEGETATION OF THE BAY OF FUNDY MARSHES 293 
there than elsewhere; second, the travel tends somewhat to com- 
pact the soil on the roads, and evaporation is more rapid, other 
things being equal, from a compact than from a loose surface of 
a homogeneous soil, hence contributing to bring upthe salt. In 
places, too, the roads are lower than the neighboring surface, so 
that water would tend to drain into them with its salt, which 
would be concentrated by evaporation; but this is not the main 
cause of the presence of the salt plants there, for they occur 
on high as well as low places. On the other hand, the places on 
the marshes which seem to become most free from salt are three. 
First, there are the dikes and the ridges thrown up in digging 
the ditches; the ditch-ridges in particular become so free of salt 
as to permit not only upland salt-shy weeds to grow but even 
the still more salt-shy bushes, such as alders, roses, etc. Their 
freshness is due, no doubt, in large part to the perfection of 
their drainage, but it is more the result, I believe, of the lack of 
homogeneous continuity between the somewhat loosely heaped 
ridge and the compact marsh soil, whereby the continuity of the 
hygroscopic soil water is interrupted and hence the upward 
movement by evaporation largely diminished. The comparative 
looseness and roughness of the ditch-ridges, also, like cultiva- 
tion in a garden, lessens evaporation, which with the preceding 
factor permits the removal of salt here to be more rapid than 
its renewal. Second, there are the spots on good high marsh 
where hay-ricks have stood, on which a luxuriant weed-vegetation 
grows up. Plainly the causes are here as above indicated for 
the bald spots; the ricks preventing evaporation, there is no 
rise of salt to these places, but rather, by the movement of 
the water falling here as rain, a washing away of the salt to 
neighboring places. Much the same effect is produced by the 
Shade of the barns. Third, there are occasional, though rare, 
Spots on the high marsh, not in any way shielded from evapora- 
tion, on which weeds, and even small bushes, and in one case a 
small birch tree, stand. These places appear to me to be always 
on old and shallow marsh, and represent, I think, spots from 
which the salt has been in course of time largely removed by 
drainage and the crops. 
