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 



