422 MARION I. NEWBIGIN. 



Moseley's polyperythrin (9)^ which is widely spread in certain 

 corals and sea-anemones^ is perhaps an allied pigment. 



There is thus much reason to believe that pigments related 

 to cheetopterin and '^enterochlorophyll^' are widely spread in 

 Invertebrates. 



C. BONELLIN. 



(1) Comparison with Chsetopterin. 



The amount of bonellin at my disposal was so limited that I 

 have not been able to make a full investigation of it. There 

 are, however, certain points which seem to suggest a close 

 relation to chsetopterin, and are worthy of note. First, as to 

 the spectra, I quote from Engelmann the following points of 

 maximum absorption in neutral solutions of bonellin and 

 chcetopterin. It will be noted that, for the reasons already 

 stated, the points in the case of chaetopterin do not exactly 

 correspond to the apparent centres of the bands as determined 

 by an ordinary spectroscope. 



Bonellin . I X 635, II X 585, III X 520, IV X 490. 

 Chaetopterin I X 655, II X 600, III X 535, IV X 500. 



When compared together the two sets show some curious 

 analogies. Thus both pigments have four bands placed in 

 similar parts of the spectrum, and, curiously enough, the dis- 

 tances between the bands are almost identical in the two cases, 

 as a little calculation will show. 



In addition to its four bands, chaetopterin in strong solution 

 shows also a shading, not yet described for neutral bonellin. 



Then, as to the spectra of the acid solutions, I quote again 

 from Engelmann : 



Bonellin . I X 613, II X 570, III X 545, IV X 515. 

 Chgetopterin I X 650, II X 597, III X 560, IV X 533, V X 500? 



On comparing these spectra, no such relation as that noted 

 for the neutral solutions is observed, but there are several 

 points which require notice. In the first place, it is obvious 

 that the first band of acidified bonellin does not correspond to 

 the apparent first band of acidified chaetopterin. We have 



