Page:Proceedings of the Royal Society of London Vol 1.djvu/483

Rh or a fortnight, as much as two or three ounces at a time, of a yellow oily ﬂuid that concretes when cold.

In consequence of such instances of fat existing in considerable quantities in the lower intestines, the author endeavoured to ascer- tain whether it might not be found in the common contents of the colon, and preferred those from the duck as the subject of experiment. Mr. Brande, who undertook to make this experiment for the author, divided the matter into two parts, which were kept for a week at a temperature varying from 40° to 60"; one in pure water, the other in extremely dilute nitrous acid. In the former no perceptible quantity of fat was found; but the latter yielded by this treatment about one eighth part of fat.

When a similar experiment was made on the contents of the rectum, there was no appearance of fat produced even by the action of nitric acid.

As it appeared possible that bile might perhaps assist in the con- version of animal substances into fat, the author requested Mr. Brande to try the effect of mixing muscular ﬂesh with bile. Human muscle when digested with water alone, at the temperature of 100°, for four days, became slightly putrid Without any appearance of fat; but when digested with human bile at the same temperature it became fetid on the second day, fetid and yellow on the third, and on the fourth it had the smell of excrement, was ﬂabby, and appeared fatty on the surface.

A second experiment on beef in the bile of the ox had the same result as the preceding.

In a third experiment made also on beef with ox-bile at the temperature of 60°, there was no appearance of fat at the end of six days; and in a. fourth experiment made again at 100°, there was again no appearance of grease produced by the process.

From these experiments, says the author, we learn that the bile has the power of converting animal substances into fat; that the temperature of 100°, or nearly so, is necessary for that process; and that the change is produced just as putrefaction is beginning to take place.

With a view to ascertain whether the same process could be detected actually going on in the human intestines, a quantity of faeces that had been retained upwards of six days were examined by being mixed with water at the temperature of 100°, and allowed to cool, when a ﬁlm that appeared to be of an oily nature was found on the surface.

If, then, it be admitted that the origin of fat is such as is here conceived by the author, he remarks that the wasting of the body in various disorders of the lower bowels is accotmted for. The uses of the various turns of the colon in different animals will be explained, and the origin of fatty concretions in the gall—bladder, which are so common, may be supposed to arise from the action of the bile on the mucus secreted from its coats.