OF THE MALAYAN REGION. 13 



types of this group ; " and the resiilt of this extended comparison of specimens is stated to 

 be, " The range of variation is so great among the Foraniinifera as to include not merely 

 those differential characters which have been usually accounted specific, but also those 

 upon which the greater part of the genera of this group have been fomided, and even in 

 some instances those of its orders " (Eoraminifera, Preface, x). Yet this same group 

 had been divided by D'Orbigny and other authors into a number of clearly Ac^nQA. families, 

 genera, and species, which these careful and conscientious researches have shown to have 

 been almost all founded on incomplete knowledge. 



Professor DeCandolle has recently given the results of an extensive review of the species 

 of Oupulifer(B. He finds that the best-known species of oaks are those which produce 

 most varieties and subvarieties, that they are often surrounded by provisional species ; 

 and, with the fullest materials at his command, two-thirds of the species he considers 

 more or less doubtful. His general conclusion is, that " in botany the loicest series of 

 groups, SUBVARIETIES, VARIETIES, and RACES are very badly limited ; these can be grouped 

 into SPECIES a little less vaguely limited, which again can be formed into sufficiently precise 

 GENERA." This general conclusion is entirely objected to by the writer of the article in 

 the ' Natural History Review,' who, however, does not deny its applicability to the j)ar- 

 ticular order under discussion, wliile this very difference of opinion is another proof that 

 difficulties in the determination of species do not, any more than in the higher groups, 

 vanish with increasing materials and more acciu'ate research. 



Another striking example of the same kind is seen in the genera Hubus and Mosa, 

 adduced by Mr. Darwin himself ; for though the amplest materials exist for a knowledge 

 of these groups, and the most careful research has been bestowed upon them, yet the 

 various species have not thereby been accurately limited and defined so as to satisfy the 

 majority of botanists. 



Dr. Hooker seems to have found the same thing in his study of the Arctic flora. For 

 though he has had much of the accumulated materials of his predecessors to work upon, 

 he continually expresses himself as unable to do more than group the numerous and 

 apparently fluctuating forms into more or less imperfectly defined species*. 



Lastly, I will adduce Mr. Bates's researches on the Amazons. During eleven years he 

 accumulated vast materials, and carefullv studied the variation and distribution of insects. 

 Yet he has shown that many species of Lepidoptera, which before offered no special diffi- 

 culties, are in reality most intricately combined in a tangled web of affinities, leading by 

 such gradual steps from the slightest and least stable variations to fixed races and well- 

 marked species, that it is very often impossible to draw those sharp dividing-lines which 

 it is supposed that a careful study and full materials will always enable us to do. 



These few examples show, I think, that in every department of nature there occur 

 instances of the instability of specific form, which the increase of materials aggravates 



* In his paper on the " Distribution of Arctic Plants," Trans. Linn. Soc. xxiii. p. 310, Dr. Hooker says : — 



" The most able and experienced descriptive botanists vary in their estimate of the value of the ' specific term ' to a 

 much greater extent than is generally supposed." 



" I think I may safely affirm that the ' specific term ' has three different standard values, all current in descriptive 

 botany, but each more or less confined to one class of observers." 



" This is no question of vfhat is right or wrong as to the real value of the specific term ; I believe each is right 

 according to the standard he assumes as the specific." 



