290 
DARWINISM 
CHAP. 
as the animal grows older; then the stripes expand, and 
at last, meeting together, the adult animal becomes of a 
uniform dark brown colour. So many of the species of 
deer are spotted when young, that Darwin concludes the 
ancestral form, from which all deer are derived, must have 
been spotted. Pigs and tapirs are banded or spotted when 
young; an imported young specimen of Tapirus Bairdi 
was covered with white spots in longitudinal rows, here 
and there forming short stripes. 1 Even the horse, which 
Darwin supposes to be descended from a striped animal, 
is often spotted, as in dappled horses; and great numbers 
show a tendency to spottiness, especially on the haunches. 
Ocelli may also be developed from spots, or from bars, as 
pointed out by Mr. Darwin. Spots are an ordinary form of 
marking in disease, and these spots sometimes run together, 
forming blotches. There is evidence that colour markings are 
in some Avay dependent on nerve distribution. In the disease 
known as frontal herpes, an eruption occurs which corresponds 
exactly to the distribution of the ophthalmic division of the 
fifth cranial nerve, mapping out all its little branches even 
to the one which goes to the tip of the nose. In a Hindoo 
suffering from herpes the pigment was destroyed in the arm 
along the course of the ulnar nerve, with its branches along 
both sides of one finger and the half of another. In the leg 
the sciatic and scaphenous nerves were partly mapped out, 
giving to the patient the appearance of an anatomical 
diagram. 2 
These facts are very interesting, because they help to 
explain the general dependence of marking on structure which 
lias been already pointed out. For, as the nerves everywhere 
follow, the muscles, and these are attached to the various bones, 
we see how it happens, that the tracts in which distinct 
developments of colour appear, should so often be marked out 
by the chief divisions of the bony structure in vertebrates, and 
by the segments in the annulosa. There is, however, another 
correspondence of even greater interest and importance. 
Brilliant colours usually appear just in proportion to the 
1 See coloured Fig. in Proc. Zool. Soc., 1871, p. 626. 
2 A. Tylor’s Coloration, p. 40 ; and Photograph in Hutchinson’s Illustra¬ 
tions of Clinical Surgery, quoted by Tylor. 
