PDF - Wallace Online

COLOURS OF ANIMALSand the West Indies, and, among butterflies, in the smallerMoluccas, the Andamans, and Madagascar, we cannot avoidthe conclusion that in these insular localities some generalcause is at work.There are other cases, however, in which local influencesseem to favour the production or preservation of intensecrimson or a very dark coloration. Thus in the Moluccasand New Guinea alone we have bright red parrots belongingto two distinct 1 families, and which therefore most probablyhave been independently produced or preserved by somecommon cause. Here, too, and in Australia we have blackparrots and 2pigeons ;and it is a most curious and suggestivefact that in another insular sub-region that of Madagascarand the Mascarene islands these same colours reappear in3the same two groups.Sense-perception influenced by Colour of the IntegumentsSome very curious physiological facts bearing upon thepresence or absence of white colours in the higher animalshave lately been adduced by Dr. Ogle. 4 It has been foundthat a coloured or dark pigment in the olfactory region ofthe nostrils is essential to perfect smell, and this pigment israrely deficient except when the whole animal is pure white.In these cases the creature is almost without smell or taste.This, Dr. Ogle believes, explains the curious case of the pigsin Virginia adduced by Mr. Darwin, white pigs being killedby a poisonous root which does not affect black pigs. Mr.Darwin imputed this to a constitutional difference accompanyingthe dark colour, which rendered what was poisonous tothe white-coloured animals quite innocuous to the black. Dr.Ogle, however, observes that there is no proof that the blackpigs eat the root, and he believes the more probable explanationto be that it is distasteful to them ;while the white pigs,being deficient in smell and taste, eat it and are killed.Analogous facts occur in several distinct families. Whitesheep are killed in the Tarentino by eating Hypericum cris-1 Lorius, Eos (Trichoglossidae), Eclectus (Palaeornithidae).2 Microglossus, Calyptorhynchus, Turacsena.8 Coracopsis, Alectraenas.* Medico-Chirurgical Transactions, vol. liii. (1870).