PHYSIOLOGY OF THE INVERTEBRATA. 159 



paraffin lamp was the following : " a broad band in the red, 

 of which the extreme edges extended from 64.5-68.5, and 

 when this band was best seen the violet end was cut off at 

 51, and the green was darkened to 52. There was no 

 absorption of the red end. When the blood was fresh and 

 less concentrated, the blue came through on the violet side 

 of the darkening at 51, thus showing a broad dark band 

 between this part and the green. A more concentrated 

 sample of similar blood, prepared in the same way and at 

 the same time, gave a darker band in the red with the same 

 limits, but with more defined edges. The violet end was 

 similarly absorbed. There were indistinct traces of a broad 

 dim band about 59-61.5." 



" The fresh blood of another individual of the same species 

 which was dark greenish-brown, due to a combination of 

 subcuticular pigment and green blood, was examined in a 

 capillary tube. The compound character of the larval colour- 

 ing was proved by gentle pressure. The pale green blood 

 with a thickness of about i mm. gave the band in the red 

 from 65-68, the violet end, being completely absorbed at 45, 

 darkened to 5 1 (when the slit was narrowed so as to render 

 tlie band distinct). A greater thickness of blood darkened 

 the band, and cut off the violet end at 50, darkening to 52 

 (when the band was distinct). A still greater thickness 

 produced more marked results with nearly the same limits. 

 On widening the slit, no blue appecired at the absorbed end, 

 The dark band now seemed to extend to 68.5. The whole 

 spectrum was much dimmed, but this was probably due to 

 the accidental presence of fat in the blood. In this case the 

 thickness of fluid was 3.3 mm., and the colour was bright 

 green." 



The fresh blood of a dark-brown larva (P. meticulosa) pro- 

 duced a spectrum with a faint band in the red. After the 

 blood had been exposed to the air for 2\ hours it became 

 brown, but the spectrum was not altered. 



The spectrum of the green fluid contents of the alimentary 



