Mimicry in Nature. 335 



turned chrysalis on green leaves became green, those that turned 

 on Avithei'ed yellow leaves became of a withered yellow colour, 

 and the one that escaped and turned chrysalis on the lid of a box 

 is of exactly the same colour as the lid. 



The next examples are in reference to some experiments of my 

 own in India. At one time I collected the larvae of a hawk moth 

 on several occasions, and I found them sometimes bright green, 

 and sometimes red, and could not account for it. I obtained 

 some eggs of this moth {Pnnacra vir/il), and fed the half of them 

 on Cissiis, which is pink, and the others on CuUadium, which is 

 green, and, though a hot-house plant here, is very common in 

 India. Those fed on Cissiis became pink, while those fed on the 

 green leaves of the Calludium became green. I was then under 

 the mistaken impression that the colouring matter of the food 

 plants gave the colouring to the caterpillars ; but since then 

 many experiments have been made by others, and I am quite 

 convinced I was mistaken. The food plants can have nothing or 

 very little to do with it ; it is nothing more or less than the 

 surroundings. 



Mr. Poulton has made several experiments in this direction 

 with a number of caterpillars. He had a box made with a 

 number of divisions, and near the bottom of the divisions were a 

 certain number of holes. He then tied a number of caterpillars so 

 that half were in one division and half in the other, one of the 

 divisions being painted black, another red, and so on. Of 

 course this was a very uncomfortable position for the caterpillars, 

 and some died. However, some lived, and in every case the 

 chrysalis was of the colour of the surroundings in the direction 

 of which it was tied. No doubt it is the nervous system through 

 which they acquire the coloration of their surroundings, and it 

 appears to me that when a caterpillar turns into a chrysalis, the 

 the last thing his eyes rest on causes the colour of the chrysalis. 



Now the next example is the cocoon of the common English 

 emperor moth. This is also the result of some more experiments 

 made by Mr. Poulton. These caterpillars spin a silk cocoon, 

 inside which is the chrysalis. One spun in a black bag, and 

 produced a black cocoon ; while another of the same insects, and 

 of the same family, spun its cocoon on a sheet of white writing- 

 paper. The result was that every bit of the silk was perfectly 

 white. It is very difficult indeed to account for the reason of it. 

 Of course one only draws deductions as to the manner in which 

 Nature has brought about these extraordinary facts that a cocoon 

 should be white on white paper, and black in a black bag, in 

 resemblance to the surroundings. How it is done is a mystery, 

 and we must wait some years yet till it is elucidated. 



My next example is that of a spider in lichen. The spider 

 makes its home right in the middle of the lichen, waiting for its 



