* 
320 NOTICES OF BOOKS. 
multiplied to such an extent as to make it extremely difficult to know 
where to logk for any particular subject. Very full Indexes conclude 
the volume of 547 pages, and every botanist will have reason to thank 
Dr. Pritzel for the labour and skill he has employed in the work. It 
might have been improved by consulting the botanical libraries in 
England, if the author could have spared the time. 
MARSHALL, WILLIAM, ESQ.: “The Wi ater-weed, Anacharis Alsinastrum, 
some account of i£." 8vo. Pamphlet. London, 1852. Pamplin. 
We have here a very interesting account, by a gentleman of Ely, 
Cambridgeshire, of, apparently, an imported water-plant from North 
America, where said plant, according to the declaration of the most 
distinguished North American botanist, Dr. Asa Gray, does not spread 
so as to become a nuisance, —yet in England in the course of a few years 
extending itself in our rivers and canals to such an extent as to become 
a great pest. This “foreigner,” as it is called by the watermen in 
Cambridgeshire, a small insignificant-looking weed, like the smallest 
of our “ Pond-weeds ” (Potamogeton), in several counties of England 
now forms “large submerged masses of a striking appearance,” so 
large and so dense, that the passage of boats is impeded; naviga- 
tion is stopped till a clearing takes places by manual labour; in 
short, sluices are choked by it,—the * Railway Dock,” at Ely, to 
such a degree that boats could not enter till several tons were re- 
moved. For farther particulars, and how the extension of the plant 
to so many different counties is accomplished, we must refer our 
readers to the pages of the little brochure itself. At the commence- 
ment (and it is again more than once repeated) a promise is given to 
discuss “who the stranger is—whence he came—how he got here— 
and by what means he is to be got rid of” All but the last pledge is 
satisfactorily redeemed: the reply to this we were rather disappointed 
to find was by an emphatic “NoT AT ALL." This is poor comfort to 
those interested in our internal navigation, to our “watermen, sluice- 
keepers, rowers, swimmers, and fishermen,” and, last and not least, to the 
“ drainage" of our fens. An experienced officer has asserted. that the 
waters of Denver sluice, below Cambridge, have been this year a foot 
. Higher than in ordinary seasons, and he refers at least half this differ- 
_ €nce to the obstructions occasioned by the presence of “Anacharis.” - 
