228 
COLOUR IN NATURE 
CHAP. 
uniformly distributed in the larvae than in the adults, 
and that development is accompanied by a re¬ 
distribution of pigment as well as by changes in 
amount It is interesting to note that in Am¬ 
phibians as in Fishes colour-changes, whether natural 
or artificially produced, are not confined to the skin 
but occur also in internal structures, eg. the peri¬ 
toneum. 
In studying the pigmentation of larvae we may 
take first the case of the spotted salamander {Sala- 
mandra vtaculata ), where the coloration has been 
described in detail by Fischel. This salamander is 
often kept in confinement, and the vivid black and 
yellow colouring of the adult is very familiar. The 
larvae under normal conditions when nearly full- 
grown are almost entirely black, the black pigment 
occurring in spots on a somewhat lighter ground. A 
histological examination shows that the colour is due 
to the action of four factors, which are as follows :— 
(1) Pigment granules lying in the cells of the 
epidermis. 
(2) Branched pigment cells lying between the 
epidermal cells, sending their processes into the 
intercellular spaces. 
(3) Similar branched pigment cells lying beneath 
the epidermis in the true skin or dermis. 
(4) Pale yellow cells similar in character and 
position to (3) but in the normal condition largely 
concealed by these. 
In the first three cases, the pigment is melanin of 
dark brown or black colour, in the fourth it is yellow 
lipochrome. The pigment cells of the dermis — 
black and yellow—are by far the most important 
