PEODUCEB BY MAN. 787 



will readily convince himself. It has, I think, been said already 

 by some one, and may now be said again, that previously to the 

 development of our railroad system all the experiences and sensations 

 of the great majority of our rural fellow-countrymen were gained 

 within an area limited by a horizon bounded by an uninteresting 

 row of these hedgerow trees. Of the evidence for the belief that 

 this tree was really imported by the Romans, and not known here 

 previously by the Britons, however familiar it be to us Saxons, 

 I have spoken elsewhere ^. To the grounds for that belief, there 

 stated, let me here add the authority, firstly, of the Cromer forest, 

 in which no elm (not even the wych elm, of which I do not here 

 (Speak) was found ; and secondly, of Mr. Bentham 2, who says of it : 



t^ * In Britain it is the most frequent elm in central, southern, and 

 eastern England, but in the north and the west only where planted. 

 It is, indeed, doubtful, whether it be really indigenous anywhere in 

 Britain.' 



Man's increasing command over the inorganic world has, in yet 

 another way and in another time, and that our own, very power- 

 fully modified the botanical world around him ; and as this parti- 

 cular instance of the efiiciency for good and evil is a matter of some 

 practical consequence, and one which is still a subject of discussion 

 and comes into the sphere of legislative interference, I will mention 

 some of the facts concerning it. I refer to the effects which the 

 by-products of certain manufactories exercise upon the vegetation 

 of the districts in which they are situated. One of the most 

 interesting papers I have ever had the good fortune to listen to 

 was one read by my friend Mr. Robert Garner, F.L.S., at the 

 British Association Meeting held at Newcastle in the year 1863, 

 and printed in the Report for that year at p. 114, as also in his 

 'North Staffordshire Tracts,^ p. 10, reprinted from the 'Stafford- 

 shire Advertiser^ of 187 1. His words run thus ^ : — 



*With respect to chemical impurities of the air, different plants have different 

 susceptibilities for such influence, and the greater or less impurity of the atmosphere 

 may indeed be shown from the effects on plants. Thus the rhododendron will flourish 

 in an air fatal to the common laurel ; wheat will luxuriate where a holly or oak will 

 die. Some plants which appear naturally to luxuriate in the coal strata— as the oak, 

 holly, or some ferns — die when the mines begin to be worked. Fortunately, annuals 



1 'British Barrows,' pp. 721-722. Article XVII, p. 324. 



2 ' Handbook of the British Flora,' p. 746. 



3 British Association Keport, I. e. 



3Ea 



