358 MR. H. C. SORBY ON THE [May 4, 
of the eggs of the rufous Tinamou—and not to green, like that of the 
fresh eggs of the Emu. 
6. Substance giving narrow absorption-bands in the red.—Un- 
fortunately I have not yet succeeded in obtaining this in sufficient 
quantity, or sufficiently free from other substances, to be able to — 
decide whether its true colour is blue, green, or brown; but the fact 
of its giving a spectrum with several narrow absorption-bands in the 
red would certainly indicate that, when mixed with other colouring- 
matters, it would cause them to have an abnormally browner tint. 
Small quantities of it occur in very many eggs; but I have not yet 
found it so abundant in any as to exercise a more important effect 
on the general colour than to make it somewhat more dull. Since 
the entire spectrum is not accurately known, I will merely give the 
position of the different very narrow absorption-bands in millionths 
of millimetres of wave-length. The most complete spectrum shows 
three bands. On adding excess of ammonia, that nearest the red end 
alone remains, whilst the addition of a small excess of a strong acid 
removés all but the central band—and when the excess is consider- 
able, raises this band towards the blue end. ‘These facts will be 
better shown by the following table :— 
Centre of bands. 
Most complete spectrum ........ 668 648 628 
With excess of ammonia........ 668 
With" a littleracid: 2 Ie es ha 643 
Wath*much sedis, ene Se SUF » 641 
By means of these bands a very small quantity of this substance 
can easily be recognized. It is not readily decomposed—but, when 
acted upon with oxidizing reagents, may be changed into another 
colouring-matter, giving rise to a spectrum with one or two somewhat 
obscure bands. ; 
7. Lichnowanthine.—In my paper on comparative vegetal chro- 
matology *, I have described a substance which occurs in greater or 
less amount in almost all classes of plants, from the lowest to the 
highest, but is more especially abundant in, and characteristic of, 
lichens and fungi, and for this reason has been named by me lichno- 
xanthine. The spectrum shows strong general absorption of the 
blue end down to about wave-length 510 millionths of a millimetre, 
and a much weaker general absorption down to about 590 millionths. 
Acids and alkalis produce very little change; and it is very slowly 
altered by strong oxidizing reagents. I have been able to prepare it 
artificially by the decomposition of resins. Some such substance is 
undoubtedly present in small quantity in very many kinds of birds’ 
eges ; and occasionally there is so much as to materially modify the 
general colour. It may occasionally have been, to some extent, 
derived from the decayed vegetable matter of the nest, or, in the 
case of eggs which have been kept long, may be partly due to the 
growth of minute fungi; but, at the same time, a very closely allied, 
* Proc. Roy. Soc. 1873, vol. xxi. p. 462, 
