Colonisation of a Dried River-Bed. 187 
I venture to bring forward a few notes I have made upon it from 
time to time. 
I had known the stream for many years, but took no specially 
botanical interest in it till the time of its destruction. I remember 
it, however, as having luxuriant growths of Typha, Phragmites , Spar- 
ganium, Myosotis, and many other water-loving plants along its banks; 
and thick tangles of Potamogeton, Callitriclie , Ranunculus aquatilis , 
etc. floating on its surface. 
It had a very winding course of about four miles through fields 
and marshy pasture land, and on one side there was a considerable 
plantation of willows. 
The stream was about fifteen to twenty-five feet across, locally 
widening to forty feet and more, and had an uninterrupted flow of 
two to three feet of clear water coming from a perennial spring in 
the chalk. The supply of water was tapped in the winter and 
early spring of 1900-1 by the powerful pumps of a new waterworks, 
a couple of miles from the source, and by April, 1901, all water had 
ceased to flow. The thick mud at the bottom was thus exposed and 
slowly dried, till by July it was just firm enough to walk on. It was 
at this time closely intersected by large cracks, six inches or so 
across, and as much as three to four feet deep. At the bottom of 
these cracks I found dead eels and innumerable molluscs, but there 
was only the merest trace of blackened roots and scraps of stems 
from last year’s vegetation. 
At this time the mud was very largely bare of plants, partic¬ 
ularly towards the middle of the stream where the last trickle of 
water had been, and remained uninhabited till September, when 
seedlings of Nasturtium officinale appeared, but did little that 
year. The rest of the mud supported a scattered vegetation, chiefly 
of seedlings, which grew in a very pretty way dotted over the bare mud. 
They varied much locally, but tended to grow in patches of almost 
“pure cultures” of J uncus, Scrophularia, grasses, etc. 
There were only two true aquatics still growing, viz. Ranunculus 
aquatilis var. trichophyllus and Lenina minor. The R. aquatilis grew 
in considerable numbers under the shelter of the higher plants, 
sometimes in large patches and sometimes isolated. The seedlings 
were of entirely aquatic type, all the leaves being minutely divided, 
but they made very little progress throughout the year and were 
nearly the same size in October as they were in July, i.e. about two 
inches high ; one plant only flowered, though the flower was of full 
size and entirely normal. 
Lemna minor was growing near the edge of the stream bed, 
sheltered by willows and nettles; the plants were buried under an 
