ON CERTAIN GREEN PIGMENTS IN INVERTEBRATES. 403 



position of the band in the red^ about X 653 in the one case 

 and X 650 in the other, while they naay or may not exhibit 

 distinctly the other bands of the original cheetopterin solution. 

 In this last respect there is much variation, but it is unneces- 

 sary here to repeat the numerous spectroscopic observations 

 which were made in order to find, if possible, a valid explana- 

 tion of the variation. There is also variation in tint in both 

 solutions. When the chsetopterin bands are distinct the tint 

 of the solution exhibits an approximation towards the indefinite 

 brown-green colour of the original chsetopterin ; when less dis- 

 tinct the solution is a bright blue-green; when they are barely 

 visible the solution is a pure dull green. These observations 

 ultimately convinced me that both solutions contain a mixture 

 of pigments, the two components varying in amount. After 

 many trials I succeeded in proving this as follows. 



(1) The precipitate from the blue acid solution obtained by 

 adding marble was dissolved in ether, the ether placed in a 

 separation funnel, and concentrated hydrochloric acid cautiously 

 poured in. The acid became indigo-blue at the line of junc- 

 tion, deep green further down, and ultimately green through- 

 out ; the ether remained pure pale green. When examined 

 with a spectroscope the ether showed two bands in the red 

 (see fig. 3), one with the centre at X661 — the band of the 

 original chsetopterin ; and another with the centre at about 

 X 641, an entirely new band. If the ether be examined in very 

 thick layer the two bands approach so near as to be distin- 

 guished with difficulty, and then appear like one broad band 

 with a centre about X 653 (cf. figs. 2 and 3). In addition to 

 these two bands the ether in thick layer shows a trace of a 

 band at about X601, which corresponds to the second band of 

 the original chsetopterin solution. The acid gives a spectrum 

 showing the band in the red characteristic of chsetopterin, and 

 traces of the other bands, — that is in essence the spectrum of 



fig. 1. 



(2) The precipitate obtained by the addition of marble to 

 the green acid solution if dissolved in ether and treated with 

 concentrated acid gives the same results. Again, the ether 



