230 



Dr. A. Holt. Colouring Matters in the 



A few of the 1913 specimens had been preserved in formaldehyde solution 

 instead of in alcohol. These had retained their natural green colour, and on 

 treatment with alcohol gave a pale yellow-green solution, the organism 

 itself becoming practically colourless, no trace of purple being observed. 



This pale yellow solution showed a faint absorption in the blue and violet, 

 but no band in the orange-red. All the above greenish or yellow solutions 

 were shaken with carbon disulphide to see whether any separation of the 

 colouring matter could be effected. The green 1912 solution after repeated 

 shaking changed to a yellow, or brownish yellow, both the alcohol and carbon 

 disulphide layers being coloured to about the same tint. 



The green solution from the outer portion of a colony gave a green carbon 

 disulphide extract, the alcoholic solution becoming yellow. From the strength 

 of the colour it appeared that there was far more green than yellow pigment 

 present. The yellow solution from the inner portion of the colony gave an 

 exactly similar separation, but there appeared to be but little green pigment, 

 as the carbon disulphide became only slightly coloured. 



The greenish yellow solution from the formaldehyde-preserved specimens 

 was quite unaltered by shaking with carbon disulphide, this solvent seeming 

 to dissolve no colouring matter. 



The green carbon disulphide extracts all showed an absorption band 

 \ = 620 fifi, and general absorption for \ < 470 fi/j,, the yellow alcoholic 

 portion exhibiting only a faint general absorption in the blue and violet. 

 No satisfactory chemical observations could be made with any of these 

 solutions. Acids and alkalies gave no very characteristic reactions, as the 

 addition of either merely caused the solutions to become somewhat more 

 yellow. This was particularly the case with alkalies, acids often appearing 

 to have no action. Neutralisation of the alkaline solution did not restore 

 the original colour. Acid or alkaline hydrogen peroxide was also without 

 visible action. 



Saturated barium hydroxide solution gave a greenish precipitate with the 

 green solutions, the supernatant liquid being yellow, while with the yellow 

 solution the precipitate had a yellow tint, though the liquid was not com- 

 pletely discolored by the barium salt. There was too little precipitate to try 

 the action of an alcohol-glycerine solution of boric acid. 



The unsatisfactory nature of these reactions is mainly due, no doubt, to 

 the great dilution of the solutions employed, but the fact that neither the 

 specimens of Diazona nor the alcoholic extracts were fresh may be a con- 

 tributing factor, for chlorophyll bodies are not very stable. 



It may be mentioned that fresh chlorophyll is altered in a non -reversible 

 direction by acids, whereas the pigment from Bonellia, as described by 



