400 MARION I. NEWBIGIN. 



nearly all the colour can be removed by successive shaking 

 with ether. 



If ammonia be added to this blue solution until it remains 

 only slightly acid, the blue colour greatly diminishes in in- 

 tensity, and on shaking with ether the ether becomes brownish 

 green in colour, and gives beautifully the original four-banded 

 spectrum (fig. 1). On evaporation the ether leaves a dull 

 green pigment, which dissolves in methylated spirit to form a 

 brownish-green strongly fluorescent solution, which turns blue 

 with acid, and shows all the characters of the original solution. 

 The whole of the pigment cannot, however, be extracted from 

 the acid solution in this way, for when ammonia is added in 

 slight excess ether does not extract any pigment, chsetopterin 

 being readily soluble in ammonia to form a solution in which 

 the band in the red only is distinct. Instead of attempting to 

 neutralise the acid solution, an easy method of precipitating its 

 pigment is to add pieces of marble to it. Violent eff'ervescence 

 occurs, the blue colour is completely lost, and a dull green 

 precipitate falls, leaving the solution colourless. The pre- 

 cipitate after washing readily dissolves in methylated spirit, 

 and yields a solution of blue-green colour, more or less 

 fluorescent, and giving a four-banded spectrum. The band in 

 the red is distinct and broad. In strong solution it has the fol- 

 lowing position : 



X 6G9 - X G39, c. = X 654 ; 



that is, it has almost the same position as that of the band in 

 the red in the blue acid solution. The other three bands have 

 the same position as in neutral chsetopterin solutions ; the 

 band to the right of D is absent. The spectrum is thus that 

 of fig, 1, but with its first band replaced by that of fig. 2. On 

 standing with acid this solution turns brown; the position of the 

 band in the red does not alter, although the band at the right 

 of D may appear. The pigment thus appears to be identical 

 with that obtained by shaking the acid solution with ether. 



In attempting to explain these reactions, the first point is 

 to consider whether tliey support the view that in the case of 



