THE 
HEW PHYTOIiOGIST. 
Vol. VII., Nos. 6 & 7. 
July 31ST, 1908. 
OBSERVATIONS ON THE OSMOTIC PROPERTIES OF 
THE ROOT HAIRS OF CERTAIN 
SALT MARSH PLANTS. 
By T. G. Hill. 
[With Four Tables and Text Figs. 21—24.] 
HE factors, historical and physical, influencing the life- 
histories of plants, considered both as individuals and as 
members of communities, are of some considerable complication, 
and our knowledge of them could hardly he described as profound. 
The condition which determines the presence or absence of any 
particular plant in any particular locality is the resultant of these 
factors, which must be separately investigated before the resultant 
can be determined; and this, presumably, is the ultimate aim of 
field-physiology, or, to use the more current term, oecology. 
The work carried out on the salt-marsh known as the Bouche 
d’Erquy, in Brittany, by Professor F. W. Oliver and his comrades, 
of which the present communication is an outcome, has this end 
in view. 
The most characteristic feature of the low-lying region men¬ 
tioned, is the periodical inundation by the tides, the result of which 
is that the soil is saline to a greater or lesser extent according to 
various physical features. Further, the degree of salinity in any 
one spot is not a constant, for it obviously depends on the high 
tides, which are often sufficiently high to flood the whole of the 
area, and, at the other extreme, so low as to cover none of the 
parts under vegetation. Thus a region which is covered only by 
the highest tides becomes, during the intertidal cycle, more and 
more saline, especially during periods of relative drought, and, of 
course, all localities after rain are less saline. 
It was considered desirable to have some information regarding 
the effect of rain on the salinity of the soil; Nature afforded an 
opportunity by sending a never-to-be-forgotten downpour on the 
