302 Mr. E. B. Poulton. Essential Nature of the [Apr. 23 



varieties with (at present) more or less tendency towards the white- 

 green variety, but on the whole very uniform (probably abnormal). 

 One larva was rather more advanced and well in the fifth stage. It 

 was a bright yellowish -green variety (probably normal). 



August 18th. — Upon the same 8. Babylonica one more intermediate 

 variety, similar in size and colour to the five found on the 17th 

 (probably abnormal). 



September 2nd. — Upon an apple in a garden at Reading, a nearly 

 adult bright yellowish-green variety (rather whitish on the back, but 

 not nearly so much so as an intermediate variety). The apple leaves 

 were white underneath, and in all previous experience such a tree has 

 produced the most extreme form of whitish-green larvae. Hence the 

 occurrence is highly abnormal. In addition to the above, two larvae 

 were sent to me — one whitish-green variety, found upon the ground 

 of another garden in Reading, and doubtless feeding on apple, and 

 normal : another from the same garden as that in which I found the 

 larva on September 2nd. This larva had turned brown, and was 

 found upon a gravel path, but it was described as bright yellowish- 

 green, and it bore traces of having had this colour when it reached 

 me. It was found in the part of the garden where the apples grow. 

 In quite another part at a considerable distance there is a tree of 

 8. Babylonica, but it is not at all probable that the larva fed upon 

 this plant. On the whole there is strong evidence for believing that 

 this larva was another bright yellowish-green variety feeding ab- 

 normally upon apple. 



17. Experiments upon Captured Larvce of S. Ocellatus. 



Experiments were made upon some of these larvae to ascertain if 

 it was possible, by changing the food, to modify their colours after 

 a definite tendency had appeared. Such experiments could of course 

 only be applied, with any hope of success, to the youngest of the 

 above-mentioned larvae. 



The bright yellowish- green variety in the fifth stage (with 

 brownish-red patches) found -August 7th, on 8. Rubra, was given 

 apple August 8th, its length (when extended) being 40 mm. On 

 August 14th, this larva was 58 mm. long when measured at rest in 

 the sphinx attitude. It was now f nil-fed and became brownish. The 

 colour was quite unchanged up to this point, and thus an immense 

 amount of food can be eaten and great additional weight gained 

 without any effect on the colour. 



The other very similar larva found on 8. Rubra, August 7th, was 

 not quite so yellow as that just mentioned, but by August 10th it had 

 become about the same. It was now fed upon apple, and was adult 

 (and turned brownish) August 18th, without any recognisable dif- 



