On the question of actual river pollution—there are two adjacent
streams in Hertfordshire which have quite defeated modern science. One of them, not long ago a very line trout stream—and the brown trout is a sort of emblem of purity —is to-duy entirely fishless : roach, dace, gudgeon, and crayfish (I think even sticklebacks) have gone the way of the finer fish. Explanations of authorities have all been in the nature of vague and sometimes foolish suggestions. Yet the causes cannot be very obscure compared with obscurities penetrated in other media. Our marine biologists are superior, perhaps, to our fresh-water biologists. Such expert work as has been expended on the scales of salmon—with marvellous results—has not been spent on the chemical and mechanical causes of water pollution. Some of the most deadly bacilli have been discovered ; but their known enemies are not present in some of the streams that have lost their denizens.
* * * *
Previous page
