416 
SAVAGE SUDAN 
immobility (aided in certain cases by mimicry), whereby to 
escape detection by their foes. It is their feebleness that forms 
their safeguard ; though whether in their eocene intelligence 
they realise that fact lies beyond my scope. Their rigid 
immobility points the conclusion, though it falls short of 
proving it I am content to leave the question at that and 
give them the benefit of the doubt. 
Immobility is the essence of the whole question. The giant 
elk, in his smoke-grey pelt, assimilates so exquisitely with forest- 
shades beneath the pines, that he may very easily escape detec¬ 
tion, though he stand 6 feet high, his position known, and within 
ioo yards of the hunter; but one flick of a white-fringed ear 
betrays him. So, as I write this at my window, with eyes 
glued to the foolscap, the flight of a passing heron, or plover, 
or gull, the capering of a rabbit 200 yards away across the 
river, unfailingly attracts attention . 1 Nothing that moves , even 
though but a part—an ear or a tail—is protected, be its colour 
what it may. As a general rule the reverse holds true—that a 
creature, provided it remains stationary, is unlikely to be dis¬ 
covered. To this latter, however, there are exceptions. For 
example, so conspicuous are the white facial adornments of 
waterbuck, sable and roan antelopes that, even when standing 
at gaze in absolute quiescence, although concealed among thick 
covert, these animals will often be detected thereby, despite 
the otherwise general harmony of their hues with those of the 
bush around. 
The zebra has customarily been selected as an illuminative 
example of the principle of colour-protection. Precisely why, it 
is difficult to understand, since scarce an animal on earth is more 
conspicuously coloured—a “thunder and lightning” pattern, to 
borrow Dr Drummond’s description. Possibly the selection 
lent occasion for a sort of gladiatorial display in dialectics; since 
there are controversialists who revel in Herculean feats, such 
as squaring the circle or demolishing (on paper) the granite 
rocks. 
Their contention is that beyond a certain distance—say 
1 It may be of interest to mention that during upwards of a score of 
years, I have kept systematic notes of the birds identified from the said 
window. It overlooks North Tyne and a wide sweep of country—moor, 
wood, and water. At present the list exceeds one hundred species. 
