428 MARION I. NEWBIGIN. 



Whether the suggestion as to the origin here made is correct 

 or not; it is at least interesting to note that in many groups of 

 Invertebrates, either in the same animal or in related forms, 

 there may occur two different sets of green pigments, distinctly 

 marked off from one another, but connected by the derivatives 

 of the more complex series. Such are bonellin and thalassemin 

 in the Echiuridae, chsetopterin and the pigment of Eulalia 

 in the Chsetopoda, enterochlorophyll and the pigment of 

 Acmsea in the Mollusca; it is probable that there are many 

 other similar cases. 



Conclusion. 

 If the observation and deductions set forth in this paper are 

 correct they go to prove that there exists in Invertebrates a 

 widely spread group of pigments occurring primarily in con- 

 nection with the alimentary tract or its outgrowths, and 

 characterised by forming in alcohol fluorescent solutions 

 of indefinite colour which exhibit a complex spectrum, con- 

 sisting when fully developed of five bands. In the fluores- 

 cence and in the complex spectrum these pigments resemble 

 chlorophyll, but the other characters, and especially the 

 relation to acids and alkalies, show that this resemblance 

 is entirely superficial. Of such pigments, chsetopterin, and 

 the pigment or pigments described as " enterochlorophyll," are 

 typical examples. Whatever the primary function of the pig- 

 ments — and of this I have nothing to say — they at least so far 

 resemble the bile pigments of Vertebrates that they occur 

 mingled with the contents of the gut, and at least in some 

 cases are eliminated with the faeces. It seems desirable to 

 have a general name to designate these pigments ; and in view 

 of our present ignorance of function, the position in M'hich 

 they occur, and the fact that they give rise to highly coloured 

 derivatives, seem to be the only available characters from which 

 a name can be based. Krukenberg's term hepatochrome is in 

 many respects very suitable, but it has the great disadvantage 

 that he himself used it for '' liver " pigments giving banded 

 spectra, without, so far as I can find, defining it clearly. 



