( xviii ) 



which three possessed the pink tubercles, instead of the 

 normal golden colour ; in 1886 larvae were obtained from a 

 pair of moths (male and female) which were developed from 

 two of the larva? with pink tubercles. Out of the eighty-eight 

 larvae thus obtained no less than sixty-four possessed pink 

 tubercles. 



"11. Phytophagous larva and many species of food-plant. — 

 Many partially-grown larvae were described as refusing well- 

 known species of food-plant, which would have been readdy 

 eaten had the larvae been hatched upon the plant ; thus a 

 special relation, which did not exist in the newly-hatched 

 larva, may grow up between the latter and its food-plant 

 within the limits of a single larval life. These facts were 

 shown to partially remove the apparent difficulties in the way 

 of an alteration in the food-plants of a species in its spread 

 into new countries, &c. 



" 12. Origin of carnivorous habits in phytophagous larva. — 

 It was shown that purely plant-eating larvae (such as D. 

 vinula, 8. ocellatus, and A. betularia) become carnivorous when 

 from any accident they are deprived of vegetable food, the 

 well-known propensities (nibbling each other's horns) of 

 the two species first-mentioned being largely dependent, in 

 frequency and in degree, upon the quality and amount of the 

 normal food. It was argued that confirmed carnivorous 

 habits arose from the repetition of such a cause. 



" 13. Young larva: seeking light. — It was shown that the 

 young and dark larvae of 8. carpini and 1'. urticcB persistently 

 seek the light, thus perhaps supporting the conclusions of 

 Lord Walsingham as to the advantages gained by insects in 

 the absorption of radiant energy. 



" 14. The force of gravitation probably appreciated by larva. — 

 It was argued that larvae which have from any cause fallen 

 from their food- plant are probably guided in the upward 

 direction by an appreciation of this force. It was found that 

 I . urticcB larvae, placed in a closely shut box immediately after 

 removal from their food-plant, always climbed to the topmost 

 part of the box, and correspondingly shifted their position 

 when the box was turned upside down." 



In the discussion which ensued, Lord Walsingham referred 



