rOUAMTNIFERA— HERON-ALLEN AND EARLAND. 247 



APPENDIX F. 

 ON THE COLOURATION OF POLY T RE MA MINI AC BUM (PALLAS). 



It would have been a source of satisfaction to us had we been able to pronounce 

 definitely upon the chemical constitution of the red colouring matter of Polytrema, 

 and we hoped that, with the comparatively ample material afforded by our 

 collection at Ajaccio, we might have arrived at a definite conclusion. 



Bradv, in 1884 (F.C*., p. 720) observed that " a few preliminary experiments 

 suggest that it is an organic substance, and proljal)ly identical with that found 

 by Merejkowsky in a large number of nuirine organisms, and named by him 

 Zoonerythrine." Merkel, however, in his elaborate thesis {id supra, p. 298) 

 states the results of certain researches which he had undertaken, which go to disprove 

 this suggestion. That it is an organic substance there can be no question, for it 

 entirelv disappears under heat — like the colouring matter of red coral. Merkel, 

 after setting forth the processes which he employed towards the solution of the 

 question, says : — " I can hardly agree that the red pigment is Zoonerythrin, as 

 to which Merejkowsky and Krukenberg say that it dissolves easily in alcohol 

 and ether. Also, on treatment with a few drops of H0SO4, the characteristic 

 blue colour for Zoonerythrin was not observed." 



Dr. E. A. Peters has, at our request, carried orrt a series of careful experiments 

 with a view to determining the nature of the colouring matter at the Biochemical 

 Laboratory, at Cambridge. We need not go at length, in this place, into the pro- 

 cesses employed, but we append a condensed note kindly furnished to us on the 

 subject. 



PIGMENT OF POLYTREMA MINIACEUM (PALLA8). 

 By R. A. Peters, M.D. 



Extraction. — The powdered organism is placed upon a small filter paper, in 

 a filter funnel, and extracted with a small amount of dilute acetic acid. The 

 dilute acid is collected in a test tube, and poured back upon the powdered 

 organism until the calcareous matter has dissolved. More acid is added if 

 necessary. A little of the pigment goes into solution l)y treatment with dilute 

 acetic acid, but the main bulk remains upon the filter paper. Treatment with 

 hot alcohol at this stage may remove some yellow pigment. (If excess alcohol 

 is added, the residue will set to a jelly.) A small amount of hot alcohol, to 

 which a little NaOH has been added, is poured upon the filter paper. This 

 dissolves the bulk of the pigment forming a yellowish red solution. Further 

 treatment with dilute acid as desciibed l)y Newbigin (J. Phys. xxi. 23(5, 1897), and 

 then with alcohol led to tlie solution of some more pigment, l)ut no definite red com- 

 pound dissolved as described in the' case of crustaceorubin. Treatment with 

 strong acid must be avoided, as it breaks down the pigment to a yellow product. 



