i8o 
COLOUR IN NATURE 
CHAP. 
varied ; black, red, green, yellow, brown, etc., are 
apparently all common. Although there is not the 
sharp division of the life-history into two contrasted 
stages which is so obvious in many insects, yet there 
is in many cases a marked development of colour in 
ontogeny. The following facts are taken from Dr. 
M'Cook's book quoted above. 
Development of Colour .—Almost all very young 
spiders are light yellow or greenish-white ; as develop¬ 
ment proceeds the colours deepen and yellows and 
browns appear, but it is not until the spiders begin 
to weave webs on their own account that the colours 
characteristic of the species develop. The character¬ 
istic patterns may be present in the young, but differ 
in colour from those of the adult ; thus Argiope 
cophinaria has pure white markings in the situations 
in which the adult has yellow markings. A general 
deepening of tint is markedly characteristic of the 
passage from youth to maturity ; and this may take 
place to such an extent that the markings which 
are at first distinct may gradually disappear. As 
illustrations of the deepening of colour we may take 
Epeira trifolium , which is at first white, then becomes 
yellow, at full maturity displays brilliant and very 
variable colouring, and then after laying her eggs 
becomes a dull, dark colour, a change which immedi¬ 
ately precedes death. A somewhat similar series of 
colour-changes is displayed by Tegenaria medicinalis , 
which is first pale, then deep yellow, and finally 
blackish. In marked contrast to these cases, however, 
there are a few forms, like Epeira strix, which are 
deep black at the time of hatching. The last-named 
species is very variable in colour, but the adults are 
