142 Mr. E. B. Poulton. Colour-relation between the [Feb. 4, 



a larva which had been fed for its whole life upon ordinary apple 

 (mentioned at p. 300 of the paper quoted above), and which was a 

 typical whitish variety. Hence the inherited tendencies were probably 

 towards the white variety, somewhat modified in the direction of 

 intermediate. Very many fertile eggs were laid after coitus, in June, 

 1885, and were hatched about July 10th, and although a large number 

 died, a considerable mass of evidence was forthcoming from the 

 fairly numerous larvae which survived, and which were divided into 

 nineteen sets of experiments. The results of the examination of these 

 larvae on various dates are given below : — 



1. Ordinary Apple. — On August 12th two larvae (hatched July 12 

 — 16) were examined, and were in the fourth stage and very white, 

 with a peculiar transparent appearance, which seems to be often 

 caused by this food-plant. On August 20th they were both dead, 

 but there could be no doubt of the tendency of the food-plant in this 

 case. 



2. Ordinary Apple. — On August 12th four larvae (hatched July 10th) 

 were examined: three were in the last stage and one in the fourth; 

 all were very white. On August 20th all were dead except one, which 

 died on August 27th. There was no doubt about the extreme 

 tendency of the food ; but apple seemed extraordinarily fatal in its 

 effects daring this last summer. 



3. Ordinary Apple (the leaves sewn so as to expose the under sides 

 only). — One larva (hatched July 10th) was examined August 12th, 

 when it was at the end of the fourth stage and very white. On 

 August 20th it had entered the last stage, and was unchanged in 

 colour. On August 27th it was dead. There could be no doubt about 

 the strong tendency of the food, but the unsewn apple leaves pro- 

 duced such a maximum effect that there was no room left for the 

 sewn ones to do more. 



4. Ordinary Apple (the leaves sewn so as to expose the upper sides 

 only). — Three larvae (hatched July 10th) were examined August 12th, 

 when they were young in the fourth stage and very white. By 

 August 20th they were all dead, and so immature that it is impossible 

 to draw any certain conclusions. It must also be noted that in the 

 case of such broad leaves as apple, there is a constant tendency for 

 the larvae to expose considerable areas of the under surface by 

 nibbling away part of one side of the leaf. 



5. Crab (Pyrus Malus, var. acerba). — Four larvae (hatched July 

 16th) were examined August 12th, when they were very small and 

 apparently tending strongly towards the white variety. On August 16th 

 one had died, and the others were only in the third stage. On 

 August 20th they were still quite small and very white, and on 

 August 27th they were all dead, except one which died soon after. 

 As far as the observations went the larvae were typically white, but 



