394 MARION I. NEWBIGIN. 



tiaguished by its yellow or orange tint. The reaction, which 

 does not seem to have been previously described, is of some 

 importance, because it affords a readily available method of 

 recognising the pigment in cases where the amount may be 

 too small to make it easy to demonstrate its nature in any 

 other way. 



As shown by Professor Lankester, the pigment readily dis- 

 solves in cold methylated spirit to form a solution varying in 

 colour according to its strength. Very strong solutions are a 

 deep brownish-yellow colour with greenish lights; more dilute 

 ones are grey-green, while those which are very weak may be 

 almost pure green. All the solutions show a strong blood-red 

 fluorescence. The want of definiteness in the colour is very 

 characteristic, and is no doubt due to the complex spectrum, — 

 that is, to the differential absorption. The bands are not all 

 of equal intensity, and as those at the violet end disappear 

 when the solution is diluted before those at the left end of the 

 spectrum, the effect of diluting is naturally to increase the 

 amount of green in the tint. 



As shown by Professor Lankester, the spectrum of the 

 freshly extracted solution shows four bands, a very strong one 

 over the line C, and three others lying respectively to the left 

 of the lines D, E, and F. In strong solutions there is also a 

 shading at the right of the D line. For the details of the 

 spectrum reference should be made to Professor Lankester's 

 paper ; it is figured in Plate 30, fig. 1, for convenience of 

 comparison. 



On the addition of a considerable amount of acid to the 

 solution the colour changes to a dusky blue without loss of 

 the blood-red fluorescence. The spectrum shows the original 

 four bands, of which, however, the first two at least have 

 shifted slightly to the right, and an additional band, which 

 lies to the right of the D line, in the position of the shading 

 already noticed in the normal solution. Besides the slight 

 alteration in position, the original bauds in the green and 

 violet have greatly diminished in intensity. This is probably 

 due to the dilution and the slight turbidity of the solution. 



