206 TEXT-BOOK OF PHYSIOLOGY 



the former have their origin in the lumbar region of the spinal cord, from 

 which they emerge in the second to the fifth lumbar nerves; they then pass into 

 and through the sympathetic chain and the inferior splanchnic nerves to the 

 inferior mesenteric ganglion around the cells of which they arborize; the 

 post-ganglionic fibers pass directly to the muscle-fibers of the intestinal wall. 

 Stimulation of the pelvic nerve with induced electric currents causes con- 

 traction of the muscle-fibers; stimulation of the hypogastric nerves causes 

 an inhibition of the contraction. 



Intestinal Fermentation. Owing to the favorable conditions in both 

 the small and large intestine for fermentative and putrefactive processes 

 e.g., heat, moisture, oxygen, and the presence of various microorganisms- 

 some of the food, when consumed in excessive quantity or when acted on by 

 defective secretions, undergoes a series of decomposition changes which are 

 attended by the production of gases and various chemic compounds. Dex- 

 trose and maltose are partially reduced to lactic acid; this to butyric acid, 

 carbon dioxid, and hydrogen. Fats are reduced to glycerol and fat acids, the 

 glycerol, according to the organisms present, yields succinic acid, carbon 

 dioxid, and hydrogen. Some of the protein derivatives the amino-acids 

 may be reduced to still simpler compounds under the action of bacteria. 

 Lysin, through the loss of a molecule of CO 2 , gives rise to cadaverin; orni- 

 thin to putrescin; tryptophan yields indol, skatol; tyrosin yields phenol^and 

 probably cresol. 



Indol. This compound is of especial interest as it is the antecedent of 

 indican, found in the urine. Though it is in part discharged in the feces, it 

 is in part absorbed into the portal blood and carried direct to the liver where 

 it is oxidized to indoxyl and combined or conjugated with potassium sulphate 

 forming the salt potassium indoxyl sulphate or indican, after which it enters 

 the blood, is carried to and eliminated by the kidneys. The presence of this 

 salt in the urine can be demonstrated by adding hydrochloric acid with a 

 small quantity of potassium chlorate; after this is done the indican combines 

 with water and undergoes a cleavage into indoxyl and potassium sulphate; 

 the former then combines with oxygen and gives rise to indigo blue. The 

 extent to which the indican is present is taken as a measure of the extent of 

 intestinal putrefaction. 



Skatol. This compound is also a derivative of the protein molecule, the 

 result of bacterial decomposition. It passes in part into the feces and gives 

 to them the characteristic odor. It is also in part absorbed into the portal 

 blood and carried direct to the liver where it is oxidized to skatoxyl, after 

 which it combines with potassium sulphate to form potassium skatoxyl sul- 

 phate after which it enters the blood and is carried to the kidneys to be elimi- 

 nated in the urine. 



Phenol and Cresol. These compounds, also derivatives of the protein 

 molecule, are absorbed into the portal blood and undergo a similar conjuga- 

 tion. They too are finally eliminated by the kidneys. 



The Feces. The feces is a term applied to the mass of material ejected 

 from the rectum through the anus. They are characterized by consistency, 

 color and odor. The origin and the nature of this material have both a 

 physiologic and a clinic interest. 



The consistency varies from day to day from liquid to solid, depending 

 partly on the character of the food, the rapidity with which it is transported 



