ON CERTAIN GREEN PIGMENTS IN INVERTEBRATES. 415 



into solutious of chlorophyll produces a precipitate of phyllo- 

 cyanin which differs markedly from chlorophyll^ and cannot be 

 reconverted into it. It is probably unnecessary to pursue these 

 contrasts further; a comparison of the properties of '^ entero- 

 chlorophyll " as detailed in the present paper with Schunck's 

 results (10) in the case of chlorophyll and phyllocyanin will 

 show that enterochlorophyll is a much less complex pigment. 



The apparent points of resemblance are the fluorescence, the 

 association with a yellow lipochrome, and the spectrum. Of 

 the fluorescence, a not uncommon character amongst certain 

 classes of pigments, it is not necessary to say anything. The 

 analogy of chsetopterin, and the conditions seen in the faeces of 

 Patella, show that the association of the lipochrome is an 

 accidental character of no significance. With regard to the 

 third point, the spectrum, there is more difficulty. In his first 

 paper Dr. MacMunn compared the spectra of acidified solutions 

 of chlorophyll and acidified alcoholic extracts of the " liver " of 

 Ostrea, and found them almost identical. This is at first 

 sight a very striking result, but the reflection that the first 

 solution contained a mixture of chlorophyll and phyllocyanin, 

 and the second a mixture of '' enterochlorophyll ^' and an acid 

 derivative, somewhat diminishes the force of the comparison. In 

 his second paper Dr. MacMunn compares the spectra of un- 

 altered chlorophyll and '^ enterochlorophyll" directly. The most 

 striking difi^erence is, then, the absence in the latter of a band 

 to the right of D, Such a band appears in enterochlorophyll 

 solutions on the addition of acid, which Dr. MacMunn regards 

 as evidence of the existence of " enterochlorophyll " in the 

 " reduced condition, or in the form of a chromogen." He 

 found this band in the normal extract in some cases, cf. the 

 observations of Krukenberg as quoted above (p. 411). The 

 occasional appearance of this band in both cases I am inclined 

 to regard as due to the presence in the solution of traces of 

 acid, probably derived from the gut or its contents, or to the 

 solution containing an unusually large amount of pigment 

 (cf. chsetopterin, where the band is present in very strong solu- 

 tions, p. 394). The resemblance between the spectrum of 



