1885.] Colouring of Phytophagous Larva?. 



289 



blood, which, however, does not after removal give a spectrum equal 

 to that of the living pupa, because the amount (from one specimen,) is 

 so small, and is disposed in the pupa so as to produce a maximum 

 effect. 



(fc.) The Larva of S. Populi, which had been blown and dried many 

 years ago, was of a bright yellow colour (with a few small streaks 

 and patches of green). The larval parieties were washed in water 

 and placed in 90 per cent, spirit, which became bright yellow in a few 

 hours, and gave the two bands of xanthophyll (shifted to the violet).* 



(I.) The Ova of E. Angularia were of a yellowish-green colour. A 

 single ovum examined as an opaque object gave the following spec- 

 trum : 51 — 48, 46" 75 — 45, the violet being absorbed at 43. Although 

 I could not detect the band in the red, 1 believe that a small propor- 

 tion of chlorophyll exists in the ovum, as there are some bright green 

 patches surrounded by the far more abundant yellow. The same 

 spectrum was seen in the contents of the ovum which were also 

 better treated by reflected light. The bands of xanthophyll were 

 seen in the alcoholic extract of the crushed ova, the violet being 

 absorbed to 43. 



(ra.) The Ova of S. Tiliee, Ocellatus, and Sphinx Ligustri were taken 

 from the bodies of moths which had been in my store-boxes for many 

 years (8 — 10), and were well washed to remove any of the abdomi- 

 nal contents which adhered to their outer surfaces. The ova were 

 then crushed in a mortar and extracted by 90 per cent, spirit, which 

 in all cases yielded a yellow solution giving the spectrum of xantho- 

 phyll. 



10. Comparison of the above Besults with those yielded by unaltered 

 Plant Pigments. — It is of importance for me to give the result of the 

 spectroscopic examination of leaves by the use of the same instru- 

 ment as that employed for the pigments in the larvae and pupse. 



Two calceolaria leaves were superposed, gently compressed, and 

 examined by sunlight, giving the spectrum shown on the Chart 

 (Spectrum 4). There is a distinct black band from 70 — 64*5, two 

 faint bands from 63 (nearly) to a little past 61, and from 60 (nearly) 

 — 57*5. There was also a dark band from 51 — 47*5, with the dimmed 

 blue coming through between this and 43, from which the violet end 

 was completely absorbed. 



When five leaves were treated in the same way, results were ob- 

 tained which are shown on the Chart, Spectrum 5, the three bands at 

 the red end being wider, and the second and third much darker, 

 while the violet end was completely absorbed up to 51, darkened to 

 52. The same results were seen in the leaves of other plants. 



* After twelve hours the spectrum was as follows, in a thickness of 35 mm. : — 

 chief band, 47 — 49, very distinct ; second band, 44—45*5, faint but distinct; the 

 violet end absorbed at 43. — May 4th, 1885. 



