116 THE DEVELOPMENT OF BRITISH FORESTRY 



Probably what is generally known as ' acclimatisation ' 

 is mixed up with this individuality. When a new 

 species is introduced by seed, the number of plants 

 which survive is usuall}' in proportion to the resem- 

 blance which the climate of the new habitat exhibits 

 to that of the home of the species. Sub-tropical plants 

 generally would be killed out in an average Avinter in 

 Britain, the climate of the latter being below their vegeta- 

 tive range. Eucalyptus, Pinus insignis, Cupressus tnacro- 

 carpa, etc., survive the average winter in the south of 

 England and Ireland, but are killed off by average cold 

 in Scotland, and the north of England. Here and there, 

 however, one comes across occasional specimens which, 

 owing to favourable sites or unusual hardihood, are able 

 to live until the arrival of one of those severe winters 

 which indicate the climatic extremes peculiar to the 

 latitude. For many years Pinus maritiina was grown in 

 Denmark, but a temperature of minus 10' F. in or about 

 1860 killed them off. In 1879-1880 large numbers of 

 deodars, hollies, etc., were killed in Scotland. No doubt 

 the absolute degree of cold which can be borne by any 

 species depends greatl}^ upon the condition of the shoots as 

 regards ripening, and Table ill. is interesting in this con- 

 nection. These instances point to the fact that no species 

 can be acclimatised outside its thermal limit, whether of heat 

 or cold, and that the word can only be properly applied to 

 a new type or strain of plant which has been raised from 

 the seed of the hardier specimens, or individuals which have 

 withstood the severest winter peculiar to the climate. A 

 possible field for experiment may lie in this Avork, as 

 suggested recently by Dr. Augustine Henry before the 

 Linnsean Society, but a public department or institution 

 could alone carry it out successfully. 



The absence of true acclimatisation is seen in most 

 species which have been growing sufficiently long in this 



