128 BEITISH AND FOREIGN 



plants and animals have been added to our population, 

 both by human design and in several other casual fashions. 

 The fallow deer is said to have been introduced by the 

 Eomans, and domesticated ever since in the successive 

 parks of Celt and Saxon, Dane and Norman. The edible 

 snail, still scattered thinly over our southern downs, and 

 abundant at Box Hill and a few other spots in Surrey or 

 Sussex, was brought over, they tell us, by the same lux- 

 urious Italian epicures, and is even now confined, imagi- 

 native naturalists declare, to the immediate neighbourhood 

 of Eoman stations. The mediaeval monks, in like manner, 

 introduced the carp for their Friday dinners. One of our 

 commonest river mussels at the present day did not exist 

 in England at all a century ago, but was ferried hither 

 from the Volga, clinging to the bottoms of vessels from the 

 Black Sea, and has now spread itself through all our brooks 

 and streams to the very heart and centre of England. 

 Thus, from day to day, as in society at large, new introduc- 

 tions constantly take place, and old friends die out for ever. 

 The brown rat replaces the old English black rat ; strange 

 weeds kill off the weeds of ancient days ; fresh flies and 

 grubs and beetles crop up, and disturb the primitive 

 entomological balance. The bustard is gone from Salis- 

 bury Plain ; the fenland butterflies have disappeared with 

 the drainage of the fens. In their place the red-legged 

 partridge invades Norfolk ; the American black bass is 

 making himself quite at home, with Yankee assurance, in 

 our sluggish rivers ; and the spoonbill is nesting of its 

 own accord among the warmer corners of the Sussex downs. 

 In the plant world, substitution often takes place far 

 more rapidly. I doubt whether the stinging nettle, which 

 renders picnicking a nuisance in England, is truly in- 

 digenous ; certainly the two worst kinds, the smaller nettle 

 and the Roman nettle, are quite recent denizens, never 



