214 Wager: Movements of Aquatic Micro-Organisms. 
gravity is negligible and the organisms swim towards the 
light, even when crowded together and this in deep water, 
such as that in a pond. If the light be cut off or much dim- 
inished, gravity acts once more and they sink. This explains 
the sudden clearing of a pond when a cloud passes over the 
sun. 
All these varied movements, due to the action of both 
light and gravity, are of great benefit to Euglena. As we have 
seen, Euglena obtains its food either through its chlorophyll, 
as in a green plant, or as a saprophyte by the absorption of 
organic material. For carbon fixation frequent insolation at 
the surface of the water is obviously important but the 
clustering of the motile cells at the surface must not be dense 
nor long continued. If it were, the organisms would obstruct 
one another, assimilation and respiration would be hindered and 
the organic food in the lower depths of the pool would be 
insufficiently utilised. The action of gravity obviates such 
disadvantages by causing densely clustered cells to sink and 
setting up a continuous circulation of the organisms, which 
are induced to move steadily from the depths to the well-lit 
surface and then from the surface to the depths.* 
FLOWERING PLANTS. 
Re = discovery of an Uncommon Sedge in the East 
Riding.— It will be interesting to students of topographical 
botany to note that on the 29th May last, a rather un- 
common sedge, Car ex axillaris Good, was found by the writer, 
growing in a fairly large tussock on the bank of the Skidby 
Drain near the Beverley Road, about two-and-a-half miles from 
Hull. The plant was just in the flowering stage, but Mr. A. 
Bennett, to whom specimens have been submitted, has no 
doubt about its identity. The first record of C. axillaris for 
the neighbourhood of Beverley, was made by the late Robert 
Teesdale, to whom plants were shown by the late Colonel 
Machell, circa 1790 A.D. In ‘ The Flora of the E.R. Yorks ’ 
(1902), where this fact is mentioned with the ‘ fide ’ of R. 
T[eesdale], it is stated that no confirmation had been made of 
late, but the semi-prophetic words which follow — ‘ it may still 
be present ’ — have now had fulfilment. One would be glad to 
learn of similar confirmation of good, old observers’ records 
still in doubt, such as those of Carex elongata (Langwith) and 
C. filiformis (marshes, Beverley), as has recently been done for 
Carex pseudo-cyperus (near Meaux). — J. F. Robinson. 
* Wager, ‘ The Action of Gravity upon the Movements of an Aquatic 
Micro-organism.’ Science Progress, Yol. 6, 19x1. 
Naturalist, 
