THE INFLUENCE OF MAN. 339 



(i) Bacteria with green Flagellatae, Euglena and other 

 animals, and then (2) Diatoms, Oscillatoria and Green 

 Algae. 



Thus, in Britain, it is clear that there are exceed- 

 ingly few associations of plants which are entirely 

 uninfluenced by man's multifarious activities. The 

 present population consists of a successive series of 

 vegetations which, like geological strata, cover and 

 are often mixed up with one another. There was 

 ( I ) the original Atlantic flora, in which man's influence 

 was, at first, imperceptible. Then came (2) the 

 Prehistoric Oaks and Pinewoods altered by fires, and 

 by the grazing of neolithic and other cattle. Then 

 followed the (3) Cultivated plants, with their train of 

 weeds ; and, finally, a purely artificial flora, which 

 depends upon the miner, the railway engineer, and 

 in a still greater degree upon a certain slackness in 

 artistic and scientific work. Inliers and Outliers are, 

 except in the case of the last, very difficult to find. 



Yet this is only an insignificant part of the earth's 

 history. The soil has been formed by the work of 

 Ferns and Clubmosses which have now disappeared 

 from the earth's surface. The roots of flowering 

 plants, microbes, fungi, and animals have been, through 

 ruthless extermination, forced to specialise and develop, 

 until they can co-operate efficiently with one another, 

 and thoroughly exploit the earth. Upon dry land, 

 lichens, mosses and special flowering plants have been 

 trained to occupy, and win for higher plants, bare rock 

 and barren sands. Even the sea and fresh water have 

 been populated with active vegetable labourers ; some of 

 which are made to reclaim mudbanks, others to enrich 

 the marine and estuarine mud with valuable organic 

 matter, or to support the fishes, and, in part, mankind. 



