ON CERTAIN GREEN PIGMENTS IN INVERTEBRATES. 429 



Perhajis the term " enterochrorae " might be found more 

 suitable. I should suggest it as a general term for a series of 

 pigments occurring in connection with the alimentary tract 

 and its outgrowths in Invertebrates, and characterised by 

 solubility in cold alcohol to form strongly fluorescent solutions, 

 usually of greenish tint, which give in neutral solution a four- 

 banded spectrum with a trace of a fifth band which is 

 rendered more distinct by the addition of acid. Acid also 

 changes the colour of the solution, and produces other changes 

 in the position of the bands. As further characters are to be 

 noted the power of yielding derivatives which may be soluble 

 in water, are of bright colour, exhibit simple spectra consisting 

 of one or two bands, and are without fluorescence in alcoholic 

 solution. It is probable that it will be found that such deriva- 

 tives are numerous. 



Further, while the euterochromes may be eliminated intact 

 from the body, as in Patella, the fact that forms containing 

 them not infrequently also exhibit bright green pigments, 

 soluble in alcohol without fluorescence, and often soluble in 

 water in addition, suggests the possibility that the entero- 

 chromes may in some cases, instead of being eliminated, give 

 rise to brightly coloured derivatives, capable of being employed 

 in surface coloration. 



The peculiar pigment bonellin resembles the euterochromes 

 in most of its characters, but is entirely absent from the ali- 

 mentary canal of the form in which it occurs. The same is 

 true of the pigments Pentacrinin and Antedonin, and many 

 others. Hence perhaps any reference to the " enteron " in 

 the group-name of these pigments is misleading, and such a 

 term as " polychromes " would be preferable. 



References. 



1. Heedman, W. a. — " Note on a New British Echiuroid Gephyrean, 



with Remarlcs on tlie Genera Tlialassema and Hamingia," 'Quart. 

 Journ. Micr. Sci.,' vol. xl (1897), pp. 367—384, 2 pis. 



2. KrukenberGj C. Fr. W. — "Ueber das Helicorubin und die Leberpig- 



mente von Helix pom at i a," ' Vergleich. Physiol. Studien,' 2te 

 Heihe, 2te Abt. (1882), pp. 63—69, 1 fig. 



