( vi ) 



Mr. J. H. Durrant exhibited a living larva of Cossus I'ujni- 

 perda, which had entirely lost its ordinary colour, and become 

 first pink and then white. He attributed the change, and 

 subsequent loss, of colour to the fact that it had been deprived 

 of its natural food, and fed for eighteen months on pink paper, 

 with which the box in which it was kept was lined, and sub- 

 sequently on white cardboard. 



Mr. M'Lachlan remarked that the most extraordniary 

 peculiarity about this larva, in addition to the loss of colour, 

 was the absence of the usual odour of Cossus, 



Lord Walsingham observed that it was questionable whetlier 

 the colours of larvae were dependent on the colours of their 

 surroundings, or whether they were affected by the contents 

 of the intestinal canal. 



Prof. Meldola said that the caterpillar exhibited, having 

 eaten the pink paper with which the box was lined, had most 

 probably become dyed by the colouring-matter, and he did 

 not think that the observation had much bearing on the 

 question of the protective colouring of caterpillars. It was 

 well known to physiologists that certain dye-stuffs could be 

 introduced into the tissues of animals by mixing the colouring- 

 matters with the food, and paper was frequently stained with 

 soluble coal-tar dyes, such as eosin, magenta, &c., so that it 

 was simply a case of direct dyeing of the larva. The whole 

 question of the direct influence of the colour of the food-plant 

 upon the colour of the larva had been thoroughly discussed by 

 himself in the notes to his translation of Weismann's ' Studies 

 in the Theory of Descent,' and many experiments in this direc- 

 tion had since been carried out by Mr. E. B. Poulton, whose 

 results showed most conclusively that in the larvre forming 

 the subjects of his experiments no such direct coloration by 

 the colouring-matter of the plant occurred. Mr. Poulton's 

 experiments had been fully described in papers published in 

 the ' Transactions' of the Society and elsewhere, and he (the 

 speaker) did not think it necessary to do more than to remind 

 Mr. Durrant of their general bearing. It was not impossible 

 that hi the case of certain species feeding upon flowers, or 

 upon the leaves of plants containing highly-coloured juices, 

 some such power of direct coloration leading to protective 



