40 ANIMAL COLOEATION. 



Sometimes, however, the changes are different, and there 

 may even be an increase in the darkness of the colour, due 

 possibly to chemical change in the pigments slowly taking 

 place. At a meeting of the Entomological Society of London, 

 a few years since, the well-known coleopterist, Mr. C. 0. 

 Waterhonse, exhibited some phytophagous beetles, which had 

 been exposed for twenty-five years in the public galleries of 

 the Bristol Museum, in which the colour changes were most 

 remarkable. 



Beetles whose natural colour was a brilliant red had not 

 ■diminished in brilliancy, but had changed to green ; pale 

 yellow had deepened into brown, blue into black ; while the 

 green colour of some forms had become converted into purple. 

 If such changes take place after death, it is quite conceivable 

 that they may take place during the life of the animal. The 

 pigment itself is no more alive in a living animal than it is in 

 a dead one. 



Connection between Integumental Pigments and Excretory 

 Products. 



An interesting case of the connection between an iotegu- 

 mental pigment and excreted matter has been recently 

 published by Mr. Hopkins, of Guy's Hospital. This gentleman 

 found that the yellow pigment of a number of butterflies — 

 including the following : " Brimstone," " Clouded Yellow," 

 " Common White," " Orange-tip," and " Swallow-tail " — could 

 be extracted by hot water, giving a solution with an acid 

 reaction ; the solution when evaporated gave the " murexide 

 reaction"; it yielded crystals of Uric acid wh.Qn treated with 

 hydrochloric acid, and, after a more prolonged treatment 

 with the same acid. Urea. 



There is thus no question that the colouring-matter of these 



