306 SCIENCE FROM AN EASY CHAIR 



" protective resemblances," some of them (such as that of 

 the buff-tip moth, which, with its wings closed, looks like a 

 broken birch twig) being most unexpected and fascinating. 

 In the forests of Madagascar, the whitish-grey tree lichens 

 are imitated by thread-like growths on beetles, tree-bugs, 

 locusts, and even lizards, with a wonderful concealing 

 effect, and some other flat membrane-like insects are so 

 much like the greenish and yellowish bark of trees, that 

 we actually lost a specimen for some time in the case 

 labelled " Mimicry," in which a series of these things was 

 arranged by me for the edification of visitors to the 

 Natural History Museum. It was found, after a day 

 or two, to have been present all the time with other 

 specimens on a piece of bark, from which it was indis- 

 tinguishable. 



Some eight years ago a distinguished American 

 painter, Mr. Abbott Thayer, was able to add very import- 

 antly to our knowledge of the ways in which colour 

 serves to conceal animals when in their natural surround- 

 ings. Mr. Thayer was able to do this owing to the fact 

 that he was a devoted student of woodland life. This, 

 however, alone was not enough. Mr. Thayer had the 

 special ability to deal with this subject which comes from 

 the trained eye of an artist. He had, above all, the know- 

 ledge of " tone values " and of the illusive and delusive 

 effects of false shading and of colour-spots and bars, and 

 of complementary colours and " irradiation " which only 

 a painter who deals every day in the most practical way 

 with these matters can attain to. Mr. Thayer showed 

 eight years ago and demonstrated conclusively by means 

 of models, one of which he presented to the Natural 

 History Museum at my request that in very many cases 

 it is of no use for an animal to be of the same colour as 

 its surroundings, since if the animal (a bird, or a quad- 

 ruped, or a fish) is of plump and rounded shape and is 



