264 INTESTINAL DIGESTION. 



zelius found in the healthy human faeces, 73-3 parts of water and 26-7 parts 

 of solid residue. The average of seventeen observations by Wehsarg was 

 precisely the same. In the observations of Wehsarg, the mean quantity of 

 solid matter discharged in the fasces in the twenty-four hours was 463 grains 

 (30 grammes), the extremes being 882-8 grains (57'2 grammes), and 251-6 

 grains (16-28 grammes). The proportion of undigested matters in the solid 

 residue was very small, averaging but little more than ten per cent., the mean 

 quantity in the twenty-four hours in ten observations being but 52-5 grains 

 (3-4 grammes). This was found, however, to be very variable ; the largest 

 quantity being 126-5 grains (8-2 grammes), and the smallest, 12-5 grains (0-81 

 gramme). 



Microscopical examination of the faeces reveals various vegetable and ani- 

 mal structures which have escaped the action of the digestive fluids. Weh- 

 sarg also found a " finely divided faecal matter " of indefinite structure, but 

 containing partly disintegrated intestinal epithelium. Crystals of cholester- 

 ine were never observed. Whenever the matter is neutral or alkaline, crys- 

 tals of ammonio-magnesian phosphate are found. Mucus is also found 

 in variable quantity in the faeces, with desquamated epithelium and a few 

 leucocytes. In addition, recent microscopical researches have shown the 

 presence of spores of yeast and a great variety of bacteria, which latter exist 

 in the faeces in great abundance. These organisms probably excite many 

 of the so-called putrefactive changes in the intestinal contents, which result 

 in the formation of indol, phenol, skatol, cresol etc. According to Senator, 



L\ t'o^ these P utrefac - 



* <= J 9 



' \W *&) W ^5 ^^ 



X A 



do not occur in 



the meconium. 

 ^e quantity 



of ^organic 



salts in the 



FIG. SO. Micro-organisms of the large intestine (Landois). f 33068 IS not 

 1, bacterium coli commune ; 2, bacterium lactis aerogenes ; 3, 4, the large bacilli 



of Bienstock, with partial endogenous spore-formation ; 5, the various stages of great. In ad- 



the development of the bacillus which causes the fermentation of albumen. . . 



dition to the 



ammonio-magnesian phosphate, magnesium phosphate, calcium phosphate 

 and a small quantity of iron have been found. The chlorides are either ab- 

 sent or are present only in small quantity. 



Marcet has pretty generally found in the human f asces a substance pos- 

 sessing the characters of margaric acid, and volatile fatty acids ; the latter 

 free, however, from butyric acid. He also found a coloring matter, which is 

 probably a modification of bile-pigment. Cystine is mentioned as an occa- 

 sional constituent of the faeces. 



In addition to the matters just enumerated, the following substances have 

 been extracted from the normal faeces : 



Excretine and Excretoleic Acid. Excretine was obtained from the nor- 

 mal faeces, by Marcet, in 1854. This substance crystalizes from an ethereal 

 solution in two or three days, in the form of long, silky crystals. Examined 



