Introduction : V aviation. 
.57 
is well known there; wood-rnff transplanted from the woods loses 
Examples could be added by scores. Though we cannot explain these altciat 
mechanically, facts remain; so it is with ‘ f 
birds in new localities, if isolated. How easily colour may be J 
shown by the following case of one of the Mumphagidae, C«ytka,ic “ 
made known by Dr. Chenu (Encyclopedic DHist. Nat. O.seaux 2 
p. 55'.: “Dne particularite remarquable, dont nous devons la communication 
Jules et Edouard Verreaux, si bons observateurs, c'est que les “ 
quatorre pennes alaires, qui sent d'lin si beau pourpre violatre, perdent cette 
couleur chez les individus vivants, lorsqu’elles ont dte mourllees par la plme: si 
dans cet etat, on yient a les toucher ou i. les frotter ayec to doigts, ceux-c, se 
trouyent aussltdt rougis par la couleiu- pouipree qu. a detent sur eux, e , 
sechant, ces mdmes plumes reprennent leur dclat pnmitif. Sur la ^ 
I'Oiseaux, aucun effect semblable ne se produit. Ce fai 
dans la classe des Oiseaux.”') Though this be exceptioual, no 
or mechanical alteiutions of colour occur elsewhere, be they dependent on food 
light or other external influences, touching which we ‘ 
at present. Alteration of colour in individuals, gone astray to isolated localities, 
leads us to geographical yaiiation, which should next be treated ot. 
2. Geographical Variation. 
Although it is conceivable, and indeed likely, that a 
sometimes owe its origin to dimorphism, a condition which may be dtima^ely 
due to the successful multiplication of a single f 
variation, it is nevertheless far more certain that the great ma on y ojjhe 
peculiar forms of Celebes and the neighbouring islands aie w a^ A-srinctive 
geographical species or local races, which have developed theu 
characters while geographically isolated from one another In Celebesi 
area there are about 150 species of this description now known, not to 
of a large number of partially formed races. ^heii- differen- 
the most interesting, as they show species problem of the 
tiation, and their study holds out the differences seen 
origin of species — or at least of the major y P instance, the 
are often very small, but of a very descnpti , narrower 
broader black border to the \-.alorhynchus in 
border in Talaut; the darker giey ° These differences 
North Celebes, the Ughter individuals in question to evolve 
may be due to an inherent tend y 
■D f\ nw G H. Ac. Sc. Paris 1857 XLV, 311 and 1862 
1) Compare Schlegel: J. f. 0. ^8^’ mrukfnCrg: ’ “Die Farbstoffe der Federn” in bis Vergl.- 
LIV, 660; Brebm Tierl. 3. _ed. 1891 V, 138, Krnkenbe g 
Physiol. Stud. 5. Abt. 1881, 75. g 
Meyer & "Wiglesworth Birds of Celebes (May 5*1 , ISl 
