Introduction: Variation. 
55 
temperament in individuals; some are bold and fierce, others more gentle; some 
more clever, others more stupid; some trustful, others shy; and so on. A marked 
“individuality” in birds may sometimes be noticed in their choice of their feeding 
grounds and nesting spots. 
Monstrosities. — Cases of exceptional individual variation, infraction of the 
rule of bilateral symmetry^) etc., have not fallen under our observation among 
Celebesian birds. There is a tame Duck with webless toes in the Sarasin Col- 
lection from North Celebes. 
Albinism., Melanism., etc. — Among genera occurring in Celebes albinism, 
partial or complete, seems to be most frequent in the Coucals, Centropus and 
Centrococcyx . The Hornbill, Cranorrhinus sometimes displays white spots on the 
tail, but this may be a partial reversion to a form with a white band across 
the rectrices, as seen in some allied Hornbills. Cases of albinism are so common 
in the Heron, Demiegretta sacra, that this species may be rightly termed dimorphic. 
A further advance of albinism is seen in species which are now always white, 
such as certain Herons and Swans, for it seems certain that these birds were 
at one time coloured species. 
According to the observations of Mr. K. G. Henke (see, besides, Z. ges. Orn. 
1886 III, 268), albinism, when partial, does not conform to the rule of bilateral 
symmetry. 
Partial melanism occurs in a highly variable degree in the large Talaut 
Oriole, Oriolus melanisticus, which appears to be developing into a species with 
a black upper surface. The Bittern, JLanthocmis melaenus (Salvad.) may ulti- 
mately prove to represent a case of frequent melanism in X. flavicollis. Per- 
manently black species among Celebesian birds are Ictinaetus malayensis (when 
adult), Surniculus musschenbroeki, Eudynamis (males), Rhabdotorrhinus exaratus and 
Cranorrhinus cassidix (females), Dicrurus, Corvus, Limnocorax. 
Examples of individual xanthochroism in Trichoglossus ornatus have been 
mentioned by Bruggemann, Meyer, and Guillemard among Celebesian birds 
(see text, p. 121). The species of Cacatua and Myristicivora are probably permanently 
xanthochroistic forms. The sulphur tint of the plumage of the former in life^) 
is due to the absence of the pigment fuscin, the colour parrot- green being 
caused by the yellow pigment psittaco-fulvin lying on the fuscin (see, Meyer, 
Sitzb. Ak. Wiss. Berlin 1882, 518); and the similar tint in the Nutmeg Pigeons 
is probably caused in the same manner, very possibly by the same pigment. 
Dichromatism. — The phenomenon of dimorphism seems to be classifiable 
under Individual Variation, although there are cases where it appears to mark 
the commencement of the evolution of a new species. The best illustration of 
See below p. 68 . 
2) It fades through exposure to the light in course of time in skins and stuffed examples, leaving the 
plumage white. 
