through their skins or the silk of the cocoon has been tinted. No, 

 It is more rational to account for the phenomenon by natural 

 selection, and to come to the conclusion that those insects which 

 resemble the colour of the soil upon which they settle will be more 

 fully protected from discovery than those less fortunate relatives, 

 which are unable to conceal themselves, and that heredity will 

 complete the work. Something of this sort evidently occurs in the 

 neighbourhood of coal mines and smoky manufacturing cities, 

 where negro varieties are mostly to be found. 



Food has pretty generally been looked upon as an important 

 factor in producing variation, but in the present day its influence 

 is considered very feeble ; still, there is evidence to show that it 

 possesses a certain amount of power. We have accounts of a diet 

 of madder causing some species to be turned brown. Ceitain 

 grasses are said to darken the colour of the drinker moth, pale 

 tiger moths are stated to be bred from lettuce, dark ones from 

 coltsfoot, yellow Brussel's lace moths from yellow lichens, besides 

 many others which require the confirmation of repeated experi- 

 ments ; but there can be no doubt that feedimj is productive of 

 considerable modification in the perfect insect. Feeding over an 

 extended period, particularly if followed by a long duration of the 

 chrysalis state, yields the finest moths and butterflies, those 

 which are fed up quickly under the stimulus of warmth and fresh 

 juicy food are comparatively small. Starvation will change the 

 tone of the colour to a sickly yellowish hue ; it will also render 

 ■ dull the bright tints, and of course dwarf tbe specimens. Irregular, 

 careless feeding, sometimes with an abundance of fresh food, at 

 ■others with nothing at all, or at the most with dry stale food, has 

 been known to produce varieties of such species as can survive the 

 treatment. 



Light, or the deficiency of it, was at one time expected to exert 

 an influence, but no satisfactory results have been recorded. With 

 decomposed light, my old friend, the late Edward Hopley, some 

 thirty years ago, made a series of experiments by covering his jam 

 pot cages with different coloured glasses, but the outcome was of a 

 negative nature. I did a little myself in that way, with similar 

 provoking results ; but I found that I could induce noctural 

 caterpillars to feed in the daytime by covering the cage with blue 

 or green glass, and tlius make them feed up more rapidly. The 

 wonderful effect of altering the colour of the chrysalis to pale, dark 

 or gold, or its cocoon to the tint of the surface upon which it spins 

 up by compelling the caterpillar to change in a box lined with 

 coloured or gilded paper, described by Professor Poulton in his 

 charming book on Colour, is most interesting, but it is not followed 

 hy any appreciable variation in the perfect insect. 



