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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 accounted for. The uses 

 of the various turns of the colon in different animals will be ex- 

 plained, 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. 



