COLOEATION AFFECTED BY THE ENVIRONMENT. 63 



Admiral," the "Peacoct," and others — whose chrysalids are 

 naked and freely suspended, with the dull colours of most 

 Satyrids, which undergo their ti-ansformation in the ground. 

 Similarly, the "Tiger moths " and the "Crimson Underwings " 

 contrast with the Cossidse and Agrotidae and most other 

 Noctufe; and among the Geometers the bright yellow Swallow- 

 tail moth, LJrapteryx sambucaria, Anger ona prunaria, etc., 

 may be compared with the sombrely-coloured species of the 

 genera Boarmia and Biston. 



Absence of Colour in Animals which live in Darkness not always 

 due to Absence of Light. 



It has often been pointed out that internal feeders among 

 caterpillars are usually devoid of integumental pigment; the 

 caterpillars of the clear-wing moths — SesiidaB — are thus dis- 

 tinguished, and they all feed in the interior of stems. But 

 Professor Meldola has suggested, in a note appended to 

 his translation of Professor Weismann's " Studies in the 

 Doctrine of Descent," that this is really due to the absence 

 of chlorophyll in their food, which is so frequently, directly 

 or indirectly, the cause of coloration in caterpillars. This 

 suggestion is supported by the existence of certain small 

 leaf-mining caterpillars, which are green ; in the thickness of 

 the leaves in which their tunnels are made, colour would be 

 neither advantageous nor disadvantageous ; and, as it is present, 

 it seems fair to attribute it to the chlorophyll which occurs, 

 though less abundantly, in the deeper tissues of the leaf. 



An instance rather different from the above is afforded by 

 the " larva of one of our Tiger beetles {Gicindela campestris), 

 which lives in a hole, from which its head and thorax alone 

 protrude ; and these are of the same green as the perfect 

 insect, while the rest of the body is of the usual whitish yellow 



