I 



TRANSACTIONS OP THE SECTIONS. 105 



lattxm Steetii, wholly white beneath ; three species of Dicemn, nil white beneath ; 

 several species of Paim, largely white-spotted ; while many of the pigeons have 

 light ashy tints. The birds generally, however, have rich dark colours, similar to 

 those which prevail among the butterflies. 



h\ Celebes we have a swallow-shrike and a peculiar small crow allied to the 

 jackdaw *, whiter than any of their allies in the surrounding islands; but otherwise 

 the colours of the birds call for no special remark. 



In Timor and Flores we have white-headed pigeons f, and a long-tailed fly- 

 catcher almost entirely white \. 



In the small Lord' Howe's Island we have the recently extinct white rail 

 (Nofurnis alba), remarkably contrasting with its allies in the larger islands of New 

 Zealand. 



We cannot, however, lay any stress on isolated examples of white colour, since 

 these occur in most of the great continents ; but where we find a series of species 

 of distinct genera all diftering from their continental allies in a whiter coloration, 

 as in the Andaman Islands and the West Indies, and, among butterflies, in the 

 smaller Moluccas, the Andamans, and Madagascar, we cannot avoid the conclusion 

 that in these insular localities some general cause is at work. 



There are other cases, however, in which local influences seem to favour the 

 production or preservation of intense crimson or a very dark coloration. Thus in 

 the Moluccas and New Guinea alone we have bright red pari'ots belonging to two 

 distinct families §, and which therefore most probably have been independently 

 roduced or preserved by some common cause. Here, too, and in Australia we 

 ave black parrots and pigeons || ; and it is a most curious and suggestive fact that 

 in another insular subregion^that of Madagascar and the Mascarene Islands — these 

 same colours reappear in the same two groups 51- 



Some very curious physiological facts bearing upon the presence or absence of 

 white colours in the higher animals have lately been adduced by Dr. Ogle **. It 

 has been found that a colonied or dark pigment in the olfactory region of the 

 nostrils is essential to perfect smell, and this pigment is rarely 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 pigs in 

 Virginia adduced by Mr. Darwin, white pigs being killed by a poisonous root 

 which does not aff'ect black pigs. Mr. Darwin imputed this to a constitutional 

 difference accompanying the dark colour, which rendered what was poisonous to 

 the white-coloured animals quite innocuous to the black. Dr. Ogle, however, 

 observes that there is no proof that the black pigs eat the root, and he believes the 

 more probable explanation to 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. White sheep are killed in the Tarentino by eating 

 Ili/periciim crisimm, while black sheep escape ; white rhinoceroses are said to pei-ish 

 from eating Euphnrhia candelabrum; and white horses are said to suffer from 

 poisonous food where coloured ones escape. Now it is very improbable that a 

 constitutional immunity from poisoning by so many distinct plants should, in the 

 case of such widely different animals, be always correlated with the same differ- 

 ence of colour ; but the facts are readily understood if the senses of smell and 

 taste are dependent on the presence of a pigment which is deficient in wholly white 

 animals. The explanation has, however, been carried a step further, by experi- 

 ments showing that the absorption of odours by dead matter, such as clothing, is 

 greatly afiected by colour, black being the most powerful absorbent ; then blue, red, 

 yellow, and lastly white. We have here a physical cause for the sense-inferiority 

 of totally white animals which may account for their rarity in nature: for few, 

 if any, wild animals are wholly white : the head, the face, or at least the muzzle 

 or the nose, are generally black ; the ears and eyes are also often black ; and there 

 is reason to believe that dai-k pigment is essential to good hearing, as it certainly 



* ArtaniPs monachvs, Corvu-t advcna. 



t Piihpvs einctus, P. alhocinctiis. \ Tchifrea ciffinis, var. 



§ Lori'us, Fos (Tricluig!ossic1ie\ Edccfus (Pala'ornitLit'a'). 



II Microf/hi-ni!>, Calyptorhynchui', Tiiracwiw. ^ CoracopH», Alecfrixva$. 



** Medico-Chirurgical Transactions, vol. liii. (1870). 



