68 lU. INTRODUCED SPECIES. 



natives, colonists, &c. The answer to tliis suggestion, or 

 objection against the omission of such a special category, 

 seems obvious enough. Naturalisation is not a simple 

 fact, which would admit of the simple answer to its 

 question, — " aye " or " no." Naturalisation is a matter of 

 degree, far more than one of kind ; and we have no scale 

 whereby to measure the degree of it, unless by individual 

 opinions. But the distinction between native and intro- 

 duced species is absolute and real ; the only difficulty or 

 uncertainty being in a verdict on the matter of fact. 

 There are not degrees of nativity, or degrees of introduc- 

 tion ; though there are differences of opinion regarding 

 the evidences in support of either view in reference to 

 individual species. 



With the exception of a few known importations from 

 America, as before adverted to, the most thoroughly na- 

 turalised species are perhaps now included among the 

 undoubted natives. The denizens follow close upon 

 those reputed natives ; being also deemed natives by 

 many botanists, but more or less strongly suspected to be 

 naturalised immigrants by other and often fewer bota- 

 nists. Then succeed the colonists, most of which are 

 still deemed natives by a majority among English bota- 

 nists ; are looked upon only as moi'e or less fully natu- 

 ralised plants by other botanists of England; and are 

 held to be aliens, not even naturalised, by M. De Can- 

 doUe and some very few others of his school. Lastly, 

 comes the miscellaneous group of aliens, so designated in 

 this work ; in regard to which there is the widest range 

 of non-unanimity among botanists, whether to hold them 

 natives, or naturalised, or non-established aliens. Before 

 we can make out a list or category of naturalised species 

 we have, first, to se^iarate the introduced from the native 

 species, and then, secondly, to agree upon some test 



