Introduction: Variation. 
57 
is well known there; wood-rufF transplanted from the woods loses its aroma. 
Examples could he added by scores. Though we cannot explain these alterations 
mechanically, facts remain ; so it is with insignificant variations in the colours of 
birds in new localities, if isolated. How easily colour may be infiuenced is 
shown by the following case of one of the Musophagidae^ Corythaix alhocristatus^ first 
made known by Dr. Chenu (Encyclopedie D'Hist. Nat. Oiseaux 2“® partie 1855 
p. 55): “Une particularite remarquable, dont nous devons la communication a 
Jules et Edouard Verreaux, si bons observateurs , c’est que les douze ou 
quatorze pennes alaires, qui sont d’un si beau pourpre violatre, perdent cette 
couleur chez les individus vivants, lorsqu’elles ont ete mouillees par la pluie: si, 
dans cet etat, on vient a les toucher ou a les frotter avec les doigts, ceux-ci se 
trouvent aussitot rougis par la couleur pourpree qui a deteint sur eux; et, en 
sechant, ces memes plumes reprennent leur eclat prirnitif. Sur la depouille de 
rOiseaux, aucun effect semblable ne se produit. Ce fait nous parait unique 
dans la classe des Oiseaux.”^) Though this be exceptional, no doubt chemical 
or mechanical alterations of colour occur elsewhere, be they dependent on food, 
light or other external influences, touching which we know next to nothing 
at present. Alteration of colour in individuals, gone astray to isolated localities, 
leads us to geographical variation, which should next be treated of. 
2. Geographical Variation. 
Although it is conceivable, and indeed likely, that a new species may 
sometimes owe its origin to dimorphism, a condition which may be ultimately 
due to the successful multiplication of a single case of exceptional individual 
variation, it is nevertheless far more certain that the great majority of the 
peculiar forms of Celebes and the neighbouring islands are what are termed 
geographical species or local races, which have developed their distinctive 
characters while geographically isolated from one another. In the Celebesian 
area there are about 150 species of this description now known, not to speak 
of a large number of partially formed races. The latter are in many respects 
the most interesting, as they show species in the first stages of their differen- 
tiation, and their study holds out the best hope of solving the problem of the 
origin of species — or at least of the majority of species. The ditferences seen 
are often very small, but of a very palpable description, as, for instance, the 
broader black border to the secondaries of Eos histrio in Sangi, the narrower 
border in Talaut; the darker grey of the head of Phoenicophaes calorhgnchus in 
North Celebes, the lighter grey in the South, and so on. These ditferences 
may be due to an inherent tendency in the individuals in question to evolve 
1) Compare Sclilegel: J. f. 0. 1858, 381; A. Bogdanow: C. R. Ac. Sc. Paris 1857 XLV, 311 and 1862 
LIV, 660; Brehm Tierl. 3. ed. 1891 V, 138; Krukenberg: “Die Farbstoffe der Federn” in bis Vergb- 
Physiol. Stud. 5. Abt. 1881, 75. 
Meyer & Wigles worth Birds of Celebes (May 5th, iggg). 
8 
