Colonisation of a Dried River-Bed. 191 
Later in the year the struggle between plant and plant began, 
and here it was often a case of the land plants against the water 
lovers, as e.g., when a nice bed of y uncus seedlings was smothered 
out of existence by the rapid growths of Polygonum, or Tnssilago 
Farfara overtopped Alisma plantago : but on the whole each had 
plenty of room, and the first year seems to have been a time when 
the plants were testing their powers against environment, rather 
than their strategy of warfare against each other. So that the 
lists given represent those plants which could grow and multiply on 
the drying mud of a river bottom. 
By 1902 the physical conditions were increasingly hard for the 
water plants, and Alisma plantago and R. aquatilis succumbed; but 
Spiraea ulmaria began to make advances into the stream bed, and 
the others did not appear to suffer to any extent; Scrophularia 
aqualica being distinctly better than last year. 
Lemna minor was still growing under the mud, green and 
apparently healthy. 
The land plants were reinforced by Beilis perennis , Sagina 
procumbens , Ranunculus acris and a few others, but during the early 
part of the year they did not invade the territory secured by the water 
plants. 
Leguminosae and Compositae, except for Tnssilago and Sonchus , 
were still but slightly represented, while Fun aria and Vaucheria 
both got considerable hold on the mud. The heavy rains of last 
year doubtless helped the water plants to hold their own, but 
towards the end of the year the land plants had largely increased. 
There was very little bare mud left, except at tbe places which 
had been occupied by Nasturtium officinale , this plant appearing to 
leave the soil uninhabitable for some time after its death. The 
main portion of the stream was covered by thick jungle-like growths 
of Phragmites , Typha, Sparganium , Epilobium, nettles, grass, etc. in 
apparently lawless confusion. 
Towards the source the stream-bed was composed of gravel 
lying directly on the chalk, and was without any muddy deposit. 
Here appeared a regular set of garden weeds, with no water plants 
at all, except Scrophularia aquatica , which was far more abundant 
this year than last, and even took to colonising heaps of rough flints. 
In summarising 1902 I should say that it was a time of inextri¬ 
cable confusion, while the two associations of plants fought for the 
mastery, neither appearing to gain nor lose very much. 
1903. The present year’s heavy rains have undoubtedly pro¬ 
longed the life of the water plants, but there are now only eleven 
