64 C. A. MAC MUNN. 
been made out in reference to them. They are a class of pig- 
ments of a yellow colour, which under certain influences, such 
as by the action of ferments, are changed into brownish or 
dark violet masses which are insoluble in lipochrome solvents, 
and refractory towards acids when thus changed. They occur 
in Sponges, in Ascidians, in Insects (in plants,e.g. Aethalium 
septicum),andin Holothuria poli. Krukenberg elsewhere 
states that the solution of this uranidine shows a band 
“behind”? r, which he figures. He seems to base his con- 
clusion that this pigment is a “‘uranidine” on the fact that 
when the alcohol extract is heated on the water-bath, the 
colouring matter is left brownish yellow. 
By the kindness of Professor F. Jeffrey Bell I have been able 
to make a somewhat rough examination of this colouring matter. 
The alcohol solution sent me was greenish yellow with a 
splendid blue-green fluorescence ; it showed two bands in the 
blue half of the spectrum, the first from about \ 483 to A 464, 
and another from about A 452 to A 433, the latter is therefore 
situated far over in the violet and was missed by Krukenberg. 
The solution was evaporated in vacuo. ‘The residue contained 
much sodium chloride stained with the yellow pigment. This 
yellow pigment was found to be insoluble in ether, partially 
soluble in chloroform, soluble in water and in glycerine. 
It was extracted with absolute alcohol and then showed a 
bluish-green fluorescence and gave the same bands as before. 
What remained insoluble in alcohol was soluble in water, and 
this solution also showed a green fluorescence, and had a yellow 
colour with transmitted light. This gave two bands also, the first 
from about A 483 to A 460, and the second about » 452 to A 486. 
On evaporating the alcohol solution on the water-bath 
a yellow, certainly not a brown, residue was left; with 
iodine in potassic-iodide this became a slight reddish yellow, 
with sulphuric acid faint red, passing into a kind of violet- 
brown tint, and gave no distinct colour change with nitric acid. 
On evaporating the aqueous solution on the water-bath it 
left a yellow residue which was hardly changed by iodine in 
iodide of potassium, hardly changed by sulphuric acid, perhaps 
