APPENDICES 429 



ward that is, under the sun ; this pair also looked coal-black, 

 nigro simillima cygno ; but, just as our course took us out of the 

 direct line of light, so the swans changed alternatively to piebald 

 and presently to their normal snow-white." 



Wildfowl on open coast present a precise analogue with 

 big-game on open veld. It is the old fable of the zebra in 

 another guise. Colour, whether of fur or feather, is no concrete 

 quality but merely the slave of changing conditions of light and 

 shade. Those who believe that, in either case, these big and 

 conspicuous creatures are " obliterated " by their colours, must 

 themselves be blind whether optically defective, or mentally 

 obfuscated ! 



I have selected a British example or two, so that any 

 doubter can go and test the facts for himself at home and 

 without the trouble of going to Africa. 



In the Sudan precisely the same phenomena are repeated, 

 but on larger scale, Sudan being a land of vast voids and of 

 proportionately vaster aggregations of wild creatures. The 

 setting, moreover, is more impressive since the atmosphere is 

 brighter and more refulgent. Can an army-corps of pelicans, 

 or flamingos, that carpet many acres and gleam a brilliant rose- 

 pink against murky waters or can a mile's length of golden- 

 crowned cranes tall as schoolboys and radiant in contrasts of 

 black-and-white with maroon-red conceivably be held to 

 be " obliterated " by their colours ? Enough, however, of the 

 colour-chimaera. 



There is, nevertheless, in Sudan one species and one only 

 which completely fulfils the stipulations of all my axioms at 

 p. 412, and which therefore is fairly entitled to be called " colour- 

 protected." I have been warned (this parenthetically) that 

 the admission of a single exception upsets my contention. 

 That may be so, but I do not agree. This is no mere ex parte 

 argument, arguing for arguing's sake and suppressing what 

 may appear adverse ; but an honest attempt to get right down 

 \.Q facts which are, after all, the only true basis of science. 



The bird in question is the squacco heron, a member of the 

 egret-tribe, all of which (including our subject), when seen on 

 wing, appear pure white. But whereas all the others habitually 

 alight on open foreshore or ooze, and thereon continue walking 

 about white and conspicuous as ever : in the reverse, the 



