INTRODUCTORY OBSERVATIONS. 13 



countries very imperfectly examined, equally as general 

 remarks on the distribution of species through lands, not 

 a tenth portion of which has ever been searched, must be 

 highly uncertain through lack of sufficiently complete 

 data. Hence the word " general," when applied to such 

 estimates and remarks, can in truth mean only " vague " 

 guesses or conjectural approximations. 



To look homeward for another illustration of this dif- 

 ference. Suppose, first, that one writer mentions certain 

 species as " British," — intending only to say that they 

 occur somewhere in Britain, either together or apart, 

 either in one single spot or in two thousand various 

 places, as chance may be. Suppose, again, that a second 

 writer uses the term "British " to mean that the species 

 to which it is applied are found in all the 18 provinces, 

 or in all the 82 coimties, of Britain ; also, that he 

 uses more restricting terms (say, " English, Scottish, 

 Highland, Lancastrian, Perthian," &c.) to signify a more 

 limited or more local distribution. In the former of 

 these two supposed cases, the term " British " has only a 

 general meaning; — that is to say, a vague and mexact 

 meaning. In the latter of the two cases, it has a general 

 meaning also ; — but general in the sense of a generalised 

 and much more precise signification. 



Vai'ious writers on phyto-geogTaphy have claimed credit 

 for " general remarks," which are in truth only remarks 

 of the most vague and inexact kind. It would be well 

 for the progress of knowledge, if scientific men would 

 more clearly and habitually distinguish between those 

 general remarks which are merely vague, and those which 

 are truly generalisations of facts. The shewy super- 

 ficiality of the former is easily attained, and at small 

 cost of time and thovight. True generalisations usually 

 require much time and thought, combined with a scrupulous 



