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 
to 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 
