INTRODUCTORY ESSAY. xvu 



common one, or that which now fulfils the office the species did at an earlier epoch*. For practical 

 purposes we must assume the most common form to be the most typical, for it is that which is best 

 known. In doing this, however, there is extreme difficulty in combating local prejudices; the gene- 

 ral botanist cannot give a higher place in the great scheme of Nature to a natural object on account 

 of its beauty, rarity, or local associations, any more than he can call a doubtful plant a native because 

 it looks well in his flora or herbarium; but there are local observers who cannot be brougli- 

 things in such a light, and who take the exclusion of plants accidentally introduced into the flora of 

 their neighbourhood, and the reduction of supposed local types to varieties of better known and 

 wider spread plants, as little short of an insult to their understandings, and a slight upon the natural 

 history of their village or island, and suppose that because the systematist cannot see with their eyes 

 he therefore takes a less true interest in what he observes. 



§3- 



Species are more widely diffused than is usually siq 

 This is a point upon which my own views differ materially from those of many of my fellow 

 botanists, and which, if borne out by facts, leads to a widely different estimate of the number and 

 variety of the members of the vegetable kingdom than that which is at present entertained. As with 

 the affinities and variation of species, so is it with their distribution : an extensive knowledge of the 

 subject is only to be obtained by actual observation over large areas, and many of them, or by the 

 study and comparison of the contents of many museums. It has been my singular good fortune to 

 have visited many regions of the globe, and to have entered into some details upon the dispersion of 

 bring species, which has always been a favourite pursuit of mine. I have further had the advantage 

 of collating my results with the largest and best-named botanical collections in the world, and have 

 .received a greater amount of assistance from my fellow naturalists than has fallen to the lot of most : 

 facts which in ordinary cases are the result of long study and much consultation have been placed at 

 my disposal rather than worked out by myself f. A very extended examination of these materials 

 has only tended to confirm the view which originated in my personal experience, viz. that the esti- 



* Thus the few remaining native Cedars of Lebanon may be abnormal states of the tree which was once 

 spread over the whole of the Lebanon, for there are now growing in England varieties of it that have no existence 

 in a wild state. Some of these closely resemble the Cedars of the Atlas and of the Himalayas (Deodar), and the ab- 

 sence of any valid botanical differences between these three forms tends to prove that all, though generally supposed 

 to be different species, are one. 'flie characters by which these Cedars are distinguished reside in habit, colour, and 

 length of leaf, and are in process of change and obliteration under cultivation ; if we find, then, these plants to he 

 varieties of one which is dispersed from the Atlas Mountains to Northern India, which of the three can we assume as 

 the type, but that which retains its characters over the greatest area, viz. the Cedar (Deodar) of the Himalaya? 

 whether or not that was the originally created state, or whether the species was created there or in the Atlas or in 

 Lebanon, or in some intermediate area whence it is now banished. It will be difficult to disconnect the idea of the 

 common Cedar from that of the type of its race, but the systematist may have to do so. What thus happens with 

 large trees may likewise occur with smaller plants. • I have given the most conspicuous illustration with which I 

 am familiar, but in the eyes of a naturalist it is not in the least more significant than one drawn from the study of 

 the varieties and distribution of a Moss or Grass. 



f It is impossible to over-estimate the importance of a well-studied and named herbarhun for such purposes, a 

 simple inspection of many species often giving their geographical range, and in the numerous cases in which widely 

 distributed genera have been worked up by competent authorities, the results are obtained with great accuracy. 



d ' 



