Page:Proceedings of the Royal Society of London Vol 69.djvu/324

308 position, some of which, as I have pointed out on former occasions, are very stable bodies, might be looked for in the excrements of animals.

Having treated some of the faeces of a cow that had been fed for some time on grass only, with boiling alcohol, I obtained a dark greenish- brown extract showing an acid reaction, a quantity of undigested matter consisting of stems, woody fibre, &c., being left undissolved. A little of the filtrate, on being mixed with water and shaken up with ether, gave a golden-yellow supernatant liquid, which, if chlorophyll had been present in the material used, would have shown a decided green colour, and would have exhibited the absorption spectrum of chlorophyll. In place of the latter, however, it showed the four absorption bands of phylloxanthin, as well marked, indeed, as I have ever seen them. This simple experiment proved conclusively the absence of chlorophyll, but in its place the presence of one of its products of decomposition. I have made no attempt to isolate and purify this supposed phylloxanthin, this being rendered difficult owing to the large admixture of impurities, which are chiefly of a fatty nature. The ethereal liquid just referred to would also have contained the urobilin of the fasces ifpresent, so I imagine at least if I have rightly understood what has been stated regarding that body. The pro- perties of urobilin, however, are not very marked. It is only by its absorption spectrum that it can with certainty be detected, but this spectrum is too inconspicuous and too faint to be easily seen in a solution containing at the same time phylloxanthin with its dark well- defined bands, which would completely mask those of urobilin situated as these are in the same region of the spectrum. Its presence, too, if proved, would have been of little interest from my point of view, and I therefore made no attempt to establish its presence or absence.

The extract of fasces with boiling alcohol gave, after filtration and cooling, a dark-coloured flocculent deposit, which was filtered off, dried, and treated with boiling chloroform. The filtered chloroform ic liquid left on evaporation a quantity of purplish-blue lustrous crystals. These crystals, which are of considerable interest as regards both their properties and their origin, will be described presently. They are more readily prepared by extracting cow-dung after pressure between folds of paper with cold chloroform, filtering, and evaporating the filtrate slowly in a warm place, when the substance separates in the form of brilliant semi-metallic spangles floating in the liquid, which, after collecting and washing with alcohol, have the appearance of a lustrous crystalline mass. From the brilliancy of its appearance an observer might easily be deceived as regards its quantity, which is not really large. I have, however, obtained sufficient to enable me to determine its chief properties, and to justify the conclusion that it is a derivative of chlorophyll closely resembling, though not identical with, phyllocyanin, as I shall presently show.