PRACTICAL WORK 187 



have some difference in structure which fits them for their 

 special habitat. 



The influence of man on Plant Associations is immense. Some- 

 times land is drained, and the plants that like moisture naturally 

 disappear. A few years ago a very rare species of Ranunculus 

 (R. ophioglossifolius] was found in Gloucestershire ; now it is 

 extinct in the county, owing to the drainage of that particular 

 spot. The cutting down of trees, or the planting of woods ; the 

 building of houses, or the pulling down of buildings and allowing 

 more light to enter ; the opening up the country with railways, 

 or the abandoning a district all affect the vegetation. The 

 more civilised a country is, the less is Nature seen in her 

 simplicity. The influence of man has always to be borne in mind 

 when seeking to account for the presence of any plant in a given 

 locality. 



BIBLIOGRAPHY. Kerner's Natural History of Plants, vol. i. ; Warming's 

 (Ecology of Plants; Robert Smith, Maps of Perthshire and the Edinburgh 

 District. 



