370 INFLUENCES OF CULTIVATION 



the replacing of once universally distributed food-plants by 

 pasture and arable land has led to the localization of many 

 species of insects. 



Perhaps the same vague influences have to do with the 

 gradual disappearance of the Ring Ouzel on the Pentlands, 

 where it nested commonly in the seventies of last century, 

 according to Lieut. -Colonel Wedderburn's List, but where 

 it is now seldom to be seen. 



In odd, unthought-of ways, too, cultivation tells. Arti- 

 ficial manure is spread wherever arable land is known, but 

 who takes into account its effect on the small inhabitants of 

 the soil, except in the case of a few kinds of grubs on the 

 farmer's black list ? Yet the effect of artificial manure may 

 be evident enough even on large creatures, for of a flock 

 of wild geese, Pink-footed and Barnacle, which, in the 

 spring of 1917 after the shooting season ended, moved 

 from the marshes of the Solway to feed on the adjoining 

 fields, no fewer than 200 were found dead ; and their deaths 

 were attributed to a new chemical manure with which the 

 fields had been dressed. (Field, 5 May, 1917.) 



RECLAMATION OF SWAMPS 



The extraordinary extent to which the present land surface 

 of our country is due to the disappearance of swamp can be 

 realized only by picturing the conditions which held in Scot- 

 land about the time of the arrival of man in the country. Ex- 

 cessive humidity had followed upon a dry period when forest 

 growth had made great progress. Waste waters collected; 

 swamps formed to such an extent that the forest trees rotted, 

 and falling, encouraged the formation of still deeper morasses, 

 until a large part of Scotland was little better than peat-moss. 

 Dryer climatic conditions and the growth of vegetation have 

 done much to convert the swamp to dry land, but man also 

 has played his part ever since the days of the Bronze Age, 

 when the rubbish cast from the island platforms upon which 

 his lake-villages stood contributed to the disappearance of 

 the very lakes which gave him security. 



The Romans possessed the art of draining lakes and 

 swamps. The mansions of London rise where once the Curlew 

 and the Bittern, Wild Ducks and W'ater-Hens lived and 



