Photograph by Max Mills. 
A RED DEER STAG. 
The light patch on the rump is an example of ‘“‘recognition-marks.”’ 
SOME INSTANCES OF COLOUR-PROTECTION IN 
MAMMALS. 
By R. LypEKKER. 
TN one of the side-galleries on the ground-floor of the Natural History Museum is 
placed a very interesting exhibit, which too often fails to attract the attention it 
deserves. A square box, with the front and top of glass, and lined with mottled drab 
cloth, contains two rough models of swimming ducks suspended on a horizontal bar 
running transversely through the centre. One of the ducks is covered with cloth similar 
to that with which the box is lined. The second is likewise covered with cloth of the 
same description; but the back of the model has been painted brown and the underside 
white. To a visitor who takes up a position a yard or two from the front of the box, 
the uniformly drab duck stands out most conspicuously from the background, while the 
one which has been painted dark above and light below is practically invisible. The 
reason of this difference is not far to seek. Any solid and opaque object of more or less 
cylindrical form, such as the body of an animal, supported horizontally in the open some 
distance above the ground, receives on its upper surface the light of the sky, of which 
it reflects a larger or smaller proportion according to the nature of its exterior. On the 
other hand, its under surface is thrown into deep shade. Consequently, the whole 
object stands out conspicuously from the background, no matter what may be the nature 
of the latter. 
If, however, in the case of a tawny or fawn-coloured body thus supported, the upper 
surface be darkened and the lower side lightened, the effects of the natural hght and 
shade are more or less completely counteracted, and the object tends to become invisible 
at a distance. Such artificial aids to invisibility would, however, be of but little effect 
in the case of a highly-polished object, of which the surface reflects a large proportion 
of the light fallmg upon it. On the other hand, a coating of coarse cloth, or still better 
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