II. Further observations on enterochlorophyll and allied pigments

In a paper read before the Royal Society in 1883, I described the results of an examination of the so-called “bile” of invertebrates, and showed that the alcohol extracts of their liver or other appendage of the intestine answering to that organ, showed a spectrum so like that of vegetable chlorophyll, as to have led me to assume that no essential difference exists between the spectrum of enterochlorophyll and plant chlorophyll. At that time I could not decide the points which are now considered: (1) Is enterochlorophyll due to the presence of symbiotic algæ ? (2) If not, is it animmediate food product, and merely an instance of the intra-cellular digestion of food chlorophyll ? (3) If it is not due to either of these sources, can it be proved that it is built up by the animal containing it ? (4) In what points does it differ from plant chlorophyll and that ofSpongilla ?