452 E. liAY LANK ESTER. 



that an effort was made to arrive at a further knowledge of these 

 insoluble pigments. 



A third case to which I wish to allude is the green colora- 

 tion of the blood of some Lepidopterous larvae. My friend and 

 colleague Professor Poulton has shown {' Proc. Roy. Soc.,' 

 1885, and vol. liv, 1893) strong reason to suppose that the 

 green colour of the blood in these larvae is determined by the 

 presence of chlorophyll or of etiolin in the food consumed by 

 them. He has shown that the blood gives an acid reaction ; 

 the suggestion made by him is that the green chlorophyll or its 

 immediate antecedent passes through the wall of the alimentary 

 canal from the digested food into the blood in a modified state, 

 which he calls metachlorophyll. Such a passage seems, on the 

 other hand, to be impossible without a very radical change in 

 the chlorophyll, which is itself neither diffusible nor soluble in 

 watery media. It is most desirable that the study of the green 

 pigment in the blood and skin of Lepidopterous larvae should 

 be carried further. One circumstance which induces me to 

 allude to it here is that Professor Baldwin Spencer, of Mel- 

 bourne, in his fine memoir *on Pentastoma published in this 

 Journal in 1893, vol. xxxiv, p. 31, made a suggestion similar to 

 that made by Professor Poulton in regard to the passage of chlo- 

 rophyll through the intestinal wall. Professor Spencer found 

 that the perivisceral fluid of Pentastoma was coloured blood- 

 red by haemoglobin, and he supposes that the haemoglobin has 

 passed from the cavity of the gut of the Pentastoma through its 

 wall into the perivisceral fluid. Some of the Nematoid parasites 

 of birds have a blood-red perivisceral fluid which has not been 

 examined spectroscopically. Possibly it also is due to haemo- 

 globin, and might throw further light on the question. It is a 

 noteworthy fact that the suggestion should be made from two 

 separate sources, that non-diffusible substances like chlorophyll 

 and haemoglobin pass through the wall of the alimentary canal 

 into the blood fluid unchanged or but little changed. There 

 is evidently something here worthy of further investigation. 

 With regard to the supposed occurrence of chlorophyll in the 

 blood of Lepidopterous larvae, Professor Poulton^s spectro- 



