ii PREFACE. 
for 86 actual species—has in many cases been due to original definitions that are 
inadequate, or at any rate imperfect. This undue recognition of species, though 
unfortunate, has thus been largely accidental. But excessive differentiation, though 
troublesome to the general systematist and, from its tendency to exaggerate his 
inferences, vexatious to the student of distribution, is a fault that, in spite of the 
strictures to which it is subjected, causes comparatively little inconvenience. If 
error be, as in human affairs it often is, unavoidable, it is in this direction that, 
in regional treatises, it 18 safer to err. For purely local needs it is indeed at 
times advisable, in the interests of lucidity, to treat as a species а form that the 
monographer can only admit as a variety. Even when, in more general treatises, 
iwo really conspecific forms are kept apart, the intelligent layman is willing to beheve 
that some distinction exists which is not apparent to the untrained eye. The harm 
done by excessive integration, which some authors consider a virtue, though oftener 
overlooked, is so much greater that it can hardly be overstated. Here the laity 
criticise less leniently, and when two forms that, to the observer in the field, are 
obviously distinct have been authoritatively united in the herbarium, the damage 
done to the science which field- and cabinet-worker alike desire to advance is 
incaleulable. The subjective effect of the habit is equally detrimental; habit becomes 
second nature, and at times the reducer hides, under the cloak of a specious 
erudition, work that is unsound. The indirect results of unbalanced reduction, even 
when applied in good faith, are more damaging still, The maker of invalid species 
as a rule only exaggerates actual facts; the geographical botanist is usually able 
to discount this exaggeration by a simple arithmetical process. Unconsidered 
identification, on the other hand, obscures the facts of distribution and evades 
computation ; it is, besides, too often a cause of offence on the part of those weaker 
brethren who prefer the statement of a text to the harvest of the eye. But it 
is in the domain of applied science, whereof taxonomy is at once the mistress 
and the handmaid, that the evils of undue integration are most patent; only 
those whose duty it is to deal with economic problems can fully appreciate the 
confusion that may result when the same name is applied to two, or three, or more 
distinet forms, or adequately realise the reproach to taxonomy that the custom 
involves. 
ee eee 
prevailed as to the identity and distribution of its Asiatic 
species, a study has been undertaken of the material preserved in a number of 
important collections. The herbaria consulted have been—in Asia, those of сана 
Buitenzorg, Hong-Kong, Saharanpur, Peradeniya: in England, those of Kew the 
British Museum, and the Linnean Society: in France, those of the Jardi 
š ; ardin des 
Plantes, of Mm. Drake del Castillo and L. Pierre: in Germany, that of the Ro 
Herbarium, Berlin: in Switzerland, those of Mm. de Candolle atid Barbe В, i <a 
eec that of Leiden: in Italy, that of Signor Beccari. For the buen nd 
: "Ee ds ue the writer opportunities of increasing his knowledge of this 
genus, he is under deep obligations to Dr. Тввсв, Mr. Ғовр, Mr. Durar, 
