200 COLOUR IN NATURE chap. 



take caterpillars, dragon -flies, bees, or other cases 

 where the segmentation of the body is obvious, we 

 find that, just as in leeches, the coloration bears a close 

 relation to the segments, as is seen in the banding of 

 many caterpillars, of the abdomen of dragon-flies, and 

 so on. But since the Arthropods, as compared with 

 worms, show a subordination of the individuality of 

 the segments to the needs of the whole — a synthesis 

 of segments — so we find that there is a constant 

 tendency for the pattern to dominate the whole 

 organism instead of being the result of the patterns 

 of the segments. The whole is symmetrical round a 

 median line, but is in most cases not merely due to 

 the repetition of the patterns of the segments. This 

 is especially well seen in caterpillars in the colouring 

 of, for example, the head. This is a specialised 

 region of the body often with much thickened cuticle, 

 and accordingly we find that it often differs in 

 coloration from the rest of the body. When we 

 pass from caterpillars to forms like dragon-flies or 

 bees, we find that, while the relation of the pattern 

 to the segments is obvious in the relatively un- 

 specialised abdomen, it is lost in the much modified 

 thorax. In other bees again, as in some of the 

 humble bees, the coloration has largely lost, even in 

 the abdominal region, any direct relation to the 

 segmentation. In this connection the coloration of 

 spiders offers some points of great interest. As we 

 have already seen, the markings, especially on the 

 abdominal region, are often exceedingly complex. 

 According to M'Cook, the markings tend to adopt a 

 leaf-like shape, and these folia appear to be related 

 to the little pits on the surface of the abdomen which 



