THE JOURNAL 
Or 
THE LINNEAN SOCIETY. 
(BOTANY.) 
The Heleoplankton of three Berkshire Pools. 
By B. MıtLarn Grirrreus, M.Sc. (Birm.), F.L.S 
(PLATE 1.) 
[Read 16th March, 1922.) 
Ty August 1910, a survey was made of nine pools in North Worcestershire 
with a view to ascertaining the plankton contents of relativ ely small bodies 
of water (Griffiths, 1912, 1916). The largest pool did not exceed eighteen 
acres in area, and the smallest was less than one acre. 
The following work is a continuation of this type of inv estigation, and it 
is boped to extend the survey over the lowland areas of the British Isles. 
Little work has been done on the heleoplankton of this country, although 
the larger lakes of the northern and western areas have been extensively 
studied. 
During June and July 1920, three pools were examined in the neighbour- 
hood of Reading, Berks. The largest pool was twenty-three acres in area 
and the smallest seventeen. In every case the pouls have been artificially 
constructed by the laying down of dams across stream-valleys. The pools 
are all situated in extensive private estates, and are used only for fishing and 
shooting. They lie at an elevation of about 180 feet O.D., in the relatively 
flat district between the rivers Kennet and Loddon. They are all head- 
waters, and receive their supply from low elevations little more than 200 fcet 
in height. The two Bulmershe pools drain to the Loddon, but Whiteknighis 
LINN. JOURN.—BOTANY, VOL. XLVI. B 
