ON CERTAIN GIIEKN FIGMENTS IN INVERTEBRATES. 393 



Herdraau for solutious of his new pigment^ thalassemin, and 

 to Professor W. M'Intosh for various green Invertebrates. 



A. CHyETOPTERIN. 



(1) General Characters. 



As chsetopterin occurs both in larger amount and in a purer 

 state than enterochlorophyll, it is convenient to begin with 

 some account of it. 



It is not necessary to say much with regard to its general 

 characters and mode of occurrence, for these points are fully 

 discussed in Professor Lankester's paper (5). As shown 

 there, the pigment occurs in the form of numerous minute 

 granules in the cells of the mid-region of the gut. In addition 

 to these small green granules, there occur in some of the gut 

 cells much larger round vesicles of a more brownish tint. 

 These bodies seem to me also to contain the pigment. The 

 pigment further occurs in oily drops mingled with the contents 

 of the gut. 



An interesting microchemical reaction which indicates the 

 presence of chaetopterin, or the related pigments, is afforded 

 by the use of strong acid, preferably hydrochloric. If a drop 

 of this acid be placed on the gut wall of Chsetopterus when 

 spread out on a slide, the cells, previously greenish brown, 

 turn a vivid green, or more rarely blue. The test is not 

 absolutely diagnostic, inasmuch as certain of the lipochromes 

 give a dirty greenish tint on the addition of strong hydro- 

 chloric acid, but the lipochromes in animal tissues are usually 

 uniformly diffused and not granular, and they only give the 

 reaction in the dry condition, the addition of water or alcohol 

 destroying the colour. Chsetopterin granules do not lose 

 their colour on the addition of water or alcohol, except in so 

 far as a green pigment dissolves out. Further, in the case 

 of chsetopterin the green colour can be removed by the addi- 

 tion of a little alkali, and the process repeated indefinitely, 

 which is again impossible in the case of the fleeting lipochrome 

 colour. In the general case also the lipochrome would be dis- 



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