The examination of the faeces is of much service in diseases of the intestine. The faeces represent the end product of the digestive act, consisting of residue unsuitable for further assimilation. It is evident that a thorough knowledge of the dejecta will throw light upon the nature of the activity of the intestines.

The normal faeces consist of changed and unchanged remnants of food, bacteria, traces of digestive juices, epithelial cells, and salts. The quantity of the faeces for twenty-four hours varies greatly with the kind of food taken. In a mixed diet it usually amounts to from four to seven ounces. The color of the faeces is usually dark brown owing to changed bile pigment, the bilirubin having become changed in the intestine into urobilin. The diet has great influence upon the color of the faeces. Meat produces a dark brown, milk a light yellow color, cacao a more or less brownish-red, huckleberries and claret a dirty black-brown color with a greenish hue. The salts of iron and manganese give rise to a darker color than the usual one, while bismuth produces a more or less blackish color. According to Quincke,1 all these metals are reduced to oxydule combinations which are responsible for these colors, while the former belief that these metals formed sulphides is not correct. Calomel frequently produces a greenish hue, while senna, santonin, gamboge, and rhubarb give rise to an intensely yellow color.

The faeces are normally somewhat soft in consistency and have a sausage shape. In abnormal conditions the consistency may be changed in two directions. The dejecta may be greatly hardened and appear in small balls, or in the form of very thin cylinders. On the other hand, the stools may be abnormally mushy or even liquid. The hardened stools which occasionally show grooved impressions from the taenia coli bear testimony to their long sojourn in the intestine, thus being exsiccated from the complete absorption of water. They are, however, by no means characteristic of a stenosis of the intestine. Very soft dejecta may be either watery, as for instance in cholera nostras or asiatica, or they are mixed with mucus which can be easily seen when pouring the dejecta into a glass and inverting it, when the mucus as a rule adheres to the surface of the vessel.

Odor

The characteristic odor of the faeces is normally caused by skatol and also to a less degree by indol. The fecal odor may be increased whenever the faeces have been retained much longer than normally in the intestine. On the other hand, faeces occasionally present very little or no odor when their sojourn in the intestine has been very short. As a good instance of the latter variety the so-called rice-water movements in cholera nostras and cholera asiatica may be mentioned. Movements with a fetid odor occur principally in malignant growths of the large bowel accompanied by ulcerative processes.

1 Quincke Munchner niedizinische Wochenschrift, 1896, No. 36.