INTRODUCTORY ESSAY. xvi 
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 brought to see 
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 supposed. 
' “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 
living 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. 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 à 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. The 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 be 
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. 
+ It is impossible to over-estimate the importance of a well-studied and named herbarium 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 
