1885.] 



Colouring of Phytophagous Larvce. 



287 



absorption extending to D, and of which the part from 59 — 60 cor- 

 responds to the second band of the less refrangible part of the 

 spectrum and the third band of true chlorophyll. The violet end 

 is completely absorbed from 51*5, dimmed to 52, but on widening the 

 slit a little blue comes through on the violet side of 48 ; but very 

 dimly. 



A thickness of 3 mm. gives no absorption of the red end, but shows 

 three bands at the violet end and an absorption of the extreme end. 

 The bands are (1), the chief band, from 50 — 48 ; (2), the second band, 

 from 46'25 — 45; and (3), the third band, from 42 — 43; the violet 

 being absorbed at 41. The bands become less distinct in the order 

 above given, and between them the spectrum is dimmed. The second 

 and third are best seen by an illumination from the bright sky near 

 the sun rather than from the sun itself. This spectrum is shown in 

 the Chart, Spectrum 6. v 



Comparing the spectra of the blood from pupae of which the larvae 

 had fed upon different foods, it was found that the lilac-fed individuals 

 showed greater effect at the red end than the privet-fed individuals, 

 while the converse was true of the violet end. The comparison was 

 made in a thickness of about 8 mm. and by sunlight. 



(g.) The Pupa of C. Elpenor. — A single specimen of the blood of 

 this pupa (from a brown larva) was examined (February 19th, 1885). 

 The colour was a clear reddish-brown in thick layers, almost colour- 

 less in a thickness of 3' 75 mm. It was examined in thicknesses of 

 23 mm. and 8 mm. In the former the spectra of derived chlorophyll 

 and xanthophyll were distinct (although the colour was not per- 

 ceptible). There was a faint band in the red from 69'5 (ending 

 sharply), gradually lessening to 65. There was the chief band at the 

 violet end from 50'5 — 48, and the second band was present from 

 46*25 — 45, and even the third band from 43 — 42, the violet end 

 being absorbed at 41. These appearances were only seen in certain 

 conditions of light. The first to disappear is the third band, for it 

 fuses with the absorption at the end of the violet, which, there- 

 fore, seems to be absorbed to 43. This is common in other cases 

 also. The lesser thickness also showed these effects at the blue end, 

 but not at the red end. 



(h.) The Pupa of D. Vinula. — The blood (of a single specimen) was 

 of a reddish-yellow colour (by lamplight). It was examined in a 

 thickness of 2' J 5 mm. by the light of a paraffin lamp (December 29th, 

 1885). There were no bands visible, but the violet end was absorbed 

 up to about 50. 



(i.) The Pupa of P. Machaon. — The pupae are yellow, or yellow and 

 green, or grey with dark markings. The blood of all varieties is 

 bright yellow. The fresh blood in a thickness of 35 mm. gave the 

 following spectrum in very good daylight. The chief band from 50 — 



