ON CERTAIN GREEN PIGMENTS IN INVERTEBRATES. 421 



scopic properties, the pigments show much resemblance to one 

 another. 



(7) Distribution of Enterochlorophyll. 



I have not yet made observations on this subject, but it 

 seems desirable to briefly consider the literature. Dr. MacMunn 

 describes the pigment in the Mollusca and Echinoderma as 

 well as in some other cases. In the two groups mentioned it 

 seems exceedingly common, and usually present in considerable 

 amount. Its presence in the latter is especially interesting 

 because of the existence in the group of Moseley^s (9) penta- 

 crinin and antedonin. I am strongly of opinion that these 

 two pigments are in some way related to enterochlorophyll, 

 but I am not able to explain why they should present such 

 striking difi'erences in spectra and so forth. In Echinoderms 

 " enterochlorophyll " is said to occur chiefly in the so-called 

 digestive gland, but in sea-urchins it is said also to be found in 

 the perivisceral fluid, although I have not succeeded in obtaining 

 the full spectrum there. 



As to the presence of enterochlorophyll in the great group 

 of Arthropods there is much less certainty. Dr. MacMunn 

 speaks of it as existing occasionally in the digestive gland in 

 Crustacea, but he does not seem to have obtained the full 

 spectrum, or to have isolated the pigment. I have examined 

 the pigment of the digestive glands of a few Crustacea, and 

 have not succeeded in obtaining the reactions of enterochloro- 

 phyll. If present it can only be in small amount, and the 

 most abundant pigment of the '' liver " is certainly not 

 '' enterochlorophyll " in the sense in which that name has 

 been used here. The question whether the pigment does exist 

 in Arthropods in considerable amount is one worthy of further 

 investigation. 



In the Coelenterata there seems little reason to doubt that a 

 pigment related to enterochlorophyll is widely distributed. 

 Such a pigment probably exists, for example, in An the a 

 cereus, though it appears diflScult to isolate, and presents 

 certain peculiarities (see Krukenberg [4] and MacMunn [8]). 



