CONTENTS OF THE LARGE INTESTINE. 397 



ever, to be exceedingly variable ; the largest quantity being 

 126*5 grains, and the smallest 12*5 grains. 



Microscopical examination of the faeces reveals the various 

 vegetable and animal structures which we have referred to 

 as escaping the action of the digestive fluids. Wehsarg also 

 found a " finely divided faecal matter " of indefinite structure^ 

 but containing partly disintegrated intestinal epithelium 

 Crystals of cholesterine were never observed. "Whenever the 

 matter was neutral or alkaline, crystals of the ammonio- 

 magnesian phosphate were found. 1 Mucus is also found in 

 variable quantity, in the faeces, with desquamated epithe- 

 lium, and a few leucocytes. 



The quantity of inorganic salts in the faeces is not great. 

 In addition to the aminonio-magnesian phosphate, phosphate 

 of magnesia, phosphate of lime, and a small quantity of iron 

 have been found. The chlorides are either absent or present 

 only in small quantity. 



Marcet has pretty generally found in the human faeces 

 a substance possessing the characters of margaric acid, and 

 volatile fatty acids ; the latter free, however, from butyric 

 acid. Gystine is mentioned as an occasional constituent. 2 

 He also found a coloring matter like that extracted by Yer- 

 deil from the blood and by Harley from the urine. This is 

 probably a modification of biliverdine. 



In 1854, Marcet described a new substance in the human 

 faeces, which he called excretine, and an acid called excre- 

 toleic acid, which he supposed to be a compound of excre- 

 tine. These principles and the one which we described in 

 1862, under the name of stercorine, are, as far as we know, 

 the only ones which have been recognized as characteristic 



1 Wehsarg mentions amorphous fat as always found in the fasces on micro- 

 scopic examination (p. 65). We have seen that the saponifiable fats cannot usu- 

 ally be separated from the fasces ; while amorphous stercorine might easily be 

 mistaken for fat. Wehsarg does not indicate the exact nature of the fatty mat- 

 ters which he observed. 



2 MARCET, Philosophical Transactions, 1854 



