XI 
THE COLOURS OF AMPHIBIANS 
233 
the purity and brilliancy of the colouring, as well 
as to give rise to markings. An inquiry into the 
causation of the process would be of great interest. 
Colour Variation in Larval 
As we have already seen, the larvae of Amphibians 
are very sensitive to environmental influences, their 
colour changing according to the conditions under 
which they are found. This fact was noticed both 
by Fischel and Bedriaga, and the former made some 
extensive experiments on the subject. He and one 
of his colleagues obtained a number of larvae of 
Salamandra maculata. Half were put in a fish¬ 
hatching apparatus, and the other half in standing 
water in a dish. The former displayed the ordinary 
type of coloration, the latter were distinctly lighter 
without displaying any other abnormality. The 
ground colour was a light yellowish-white, and the 
ordinary black spots were only represented by slight 
traces of dark pigment, occurring especially at the 
posterior end of the body. As well as displaying 
little pigment, the larvae are said to have had a 
peculiar glassy and transparent appearance. The 
larvae were not all uniform, but showed considerable 
variation, those in the standing water were, however, 
all much lighter than those in the running water. 
On making a histological examination of the skin 
of the pale larvae, it was found that the cells of the 
epidermis contained a much smaller amount of 
pigment than usual, while the branched pigment cells 
of this layer and of the underlying dermis were 
represented by dark-coloured oval or rounded bodies. 
