UNDIGESTED RESIDUE OF THE FOOD. 181 



tancc, as showing the mode in which injections of nutrient substances per 

 anum act in prolonging life in cases where the passage of food along the 

 upper part of the intestinal tube is interrupted. 



128. The undigested residue of the food, mingled with the products of 

 secretion that have been poured into the alimentary canal, gradually ac- 

 quires, in the large intestine, the ordinary consistency of Fteces, through 

 the continuance of the absorbent process, whereby the superfluous fluid is 

 removed. The condition of this residue has been particularly studied by 

 Dr. Rawitz and Dr. Marcet. 1 By the former observer, muscular fibres are 

 stated to be almost entirely dissolved, especially in the flesh of fish and 

 hares, though less rapidly in that of poultry and other animals, ouly a 

 few fragments remaining. Dr. Marcet, however, found muscular fibres, ex- 

 hibiting clearly their well-marked structure, almost constantly present and 

 in considerable quantities ; and he is inclined to believe that when meat is 

 daily taken, only the juices are extracted, the fibres themselves undergoing 

 but little digestive action. The cells of cartilage and fibro-cartilage, the 

 fibres of elastic tissue, 2 and fatty matter if taken in excess, are frequently 

 found unchanged in the fseces ; and crystals of cholesterin may usually be 

 obtained, especially after the use of pork fat. "As regards vegetable sub- 

 stances, Dr. Rawitz states that he frequently found large quantities of cell- 

 membranes unchanged in the fteces ; also starch-cells (which were rarely 

 seen by Dr. Marcet), deprived of only part of their contents. The green 

 coloring principle, chlorophyll, was usually unchanged. The walls of the 

 sap vessels and spiral vessels were quite unaltered by the digestive fluid, and 

 were usually found in large quantities in the faeces ; their contents, probably, 

 were removed." 3 Besides the undigested residue of the food, the microscope 

 enables us to recognize the brown coloring matter of the bile, epithelium- 

 cells and mucus-corpuscles, and various saline particles, especially those of 

 the ammouiaco-magnesian phosphate, 4 whose crystals are well defined ; most 

 of which are derived from the secretions. The quantity of fecal discharge 

 which is daily passed by an adult seems to vary from 2 to 10 oz. Dr. Ed- 

 ward Smith found the average weight in prisoners at the Colclbath Fields 

 Prison to be 8.55 oz. These men were fed upon a full dietary with brown 

 bread, and the proportion of the faeces to the solid food was as 1 : 4.5. Se- 

 vere labor on the treadmill was found to diminish the quantity of freces, 

 whilst the rest of Sunday occasioned a considerable increase. The propor- 

 tion of water was very uniform, viz., 73.5 per cent.; and an average of 41.8 

 grains of nitrogen was daily eliminated from the system by this channel. 3 

 The absolute quantity of solid matter discharged in the fasces in the twenty- 



1 Mod. Times and Gaz., July 31st, 1858. 



2 It has been pointed out to the Author by his friend Mr. Qnekett, that elastic 

 fibres are occasionally to be met with in the Human faeces, which present an appear- 

 ance of transverse division (probably resulting from incipient decomposition) closely 

 resembling that which is normal in the ligamentum nuchae of the Giraffe. So dis- 

 tinct, indeed, does the transverse division then become, that these fibres, when pecu- 

 liarly abundant (as they are in the fteces of persons who have for some time been 

 "Jiving upon mutton-chops, and have not put aside the segment of the aorta which 

 each chop includes), have actually been mistaken for a confervoul growth in the fieces. 



3 Quoted from Dr. Kirkes's Physiology. See also the Memoir of Dr. Rawitz, Ueber 

 die Einfachen Nahrungsmittel, Breslau, 1846 ; and the Analysis of Wehsarg and 

 Ihring's Inaugural Theses in Brit, and For. Med.-Chir. Rev , vol. xiv, p. 528. 



4 Crystals of this salt sometimes occur in perfectly normal faeces; and in those cases 

 in which the secreted fluids and the contents of the intestine readily undergo decom- 

 position, as in typhus, cholera, and certain forms of dysentery, they are found in 

 large numbers and of considerable size. 



5 Smith and Milner, Rep. on the Influence of Pris. Discip., Syd. Soc. Year-Book, 

 1861, p. 83. 



