- hope of its finding its way to sea; but be raked out at once 
-. upon the shores; and Commissioners of Drainage should 
16 
to spread in this active manner in America. Bebe our 
sluggish streams, the ‘decomposing vegetable and animal 
matters in our Cambridge waters, and especially the excess 
of lime present, (15 to 17 grains in the gallon), furnishing 
an inexhaustable supply of inorganic food, may account for 
its more rapid increase here than in America. 
Lastly: with respect to the question,— How is it to be got 
rid of ? I think we may answer it at once by an emphatic 
“NoT aT ALL.” Like the imported European horses and 
oxen in the South American Pampas, or Capt. Coox’s pigs 
in New Zealand, or the Norway rat in our own farm yards, 
or the Oriental black beetle in London kitchens, or (more 
remarkable still) like the exotic mollusk (the Dreissena 
Polymorpha), which has now spread itself through the canals 
of this country, we may conclude it has fairly established 
itself amongst us, never to be eradicated. All we shall be 
able to do is to try and keep it down, and in order to effect q 
this, it should not be left in the rivers after being cut, in the 
beware of letting fresh water into their districts, for the weed 
will inevitably enter with it, and blockade the ditches. 
In conclusion, Mr. Editor, you must allow me to remark — 
(while warmly thanking you for your courtesy in affording 
‘mae so much space in your valuable journal), that I should 
- never have obtruded myself on the public if I did not re- 
cognize in the introduction of this “ New Water Weed” 
_ beyond the mere scientific question, considerations of much 
local and economical importance to this Fen country. 
oe Yours obediently, 
Ely, August 30th, 1852. W. MARSHALL. 
Printed by T. Perrirr, 1, Old Compton Street, Soho. 
