Crosby.] 
140 
[May 21. 
It is evident at a glance that a perfectly pure and wholesome water 
in the eastern part of the State contains a proportion of salt which, 
farther west, w’ould indicate very serious contamination, and hence 
that the normal chlorine map is absolutely essential to the proper san- 
itary classification of the waters of the State. The table also reveals 
very clearly the source of the salt. The extremely rapid increase in 
the immediate vicinity of the sea makes it impossible to question the 
conclusion reached by Dr. Drown and Mrs. Richards that it is sim- 
ply the salt spray carried inland by the east winds. This virtually 
deprives the salt in the natural waters and, presumably, in the 
drift, of geological significance and relegates it to the fields of 
meteorologic and sanitary investigation. It is interesting, how- 
ever, to reflect that the salt air from the sea is a possible source of 
the salt found in areas of inland drainage when these are not too 
remote from the coast or cut off from the coast by mountain ranges. 
The following communication was made to the Society : — 
GEOGRAPHIC LIMITS OF SPECIES OF PLANTS IN THE 
BASIN OF THE RED RIVER OF THE NORTH. 
BY WARREN CPHAM. 
No strongly defined line of division can be drawn between dif- 
ferent portions of the flora and fauna of the country from the Atlan- 
tic to the Rocky Mountains and from the Gulf of Mexico to the 
Arctic Sea. But great contrasts exist between the eastern region 
with its plentiful rainfall and the dry western plains, as also be- 
tween the almost tropical southern margin of the United States and 
the tundras beneath the Arctic Circle. In travelling from the once 
wholly forest-covered country of the eastern states, across the prai- 
ries, to the far western plains bearing cacti and sage-brush, there 
is observed a gradual change in the flora, until a very large propor- 
tion of the eastern species is left behind, and their places are taken 
by others capable of enduring more arid conditions. Likewise in 
going from St. Augustine or New Orleans to Chicago, St. Paul, 
Winnipeg, and Hudson bay and strait, the palmettoes, the ever- 
green live oak, bald cypress, southern pines, and the festooned 
