DIGESTION. 203 



located in the upper third of the intestine, it was found that when 

 saccharose was introduced into the lower opening, it was not inverted 

 but appeared in the feces unchanged. 



Maltose is also rapidly transformed into dextrose. Lactose 

 appears to be unaffected by the pure juice. As it is non-assimilable 

 it has been supposed to undergo conversion into dextrose while pass- 

 ing through the epithelial cells of the intestinal mucosa. 



Intestinal juice also has a slight diastatic action on starch. 



THE LIVER. 



The liver is a highly vascular conglomerate gland situated in 

 the right hypochondriac region and connected with the intestine by 

 a duct. 



Inasmuch as the liver performs several functions related to both 

 secretion and excretion, a consideration of its structure and its vari- 

 ous functions will be deferred to a subsequent chapter. In this 

 connection the bile, its physical properties and chemic composition 

 in relation to the digestive process, will only be considered. 



The bile is a product of the secretory activity of the liver cells. 

 As it is poured into the intestine in man and most mammals at 

 a point corresponding to the orifice of the pancreatic duct, and most 

 abundantly at the time the food is passing through the duodenum, 

 it is usually regarded as a digestive fluid possessing an influence 

 favorable if not necessary to the completion of the general digestive 

 process. 



Anatomic Relations of the Biliary Passages. After its forma- 

 tion by the liver cells the bile is conveyed from the liver by the bile 

 capillaries, which uniting finally form the main hepatic duct./ This 

 duct emerges from the liver at the transverse fissure^ At a distance 

 of about 5 centimeters it is joined by the cystic duct, the distal ex- 

 tremity of which expands into a pear-shaped reservoir, the gall- 

 bladder, in which the bile is temporarily stored (Fig. 85). The duct 

 formed by the union of the hepatic and cystic ducts, the common 

 bile-duct, passes downward and forward for a distance of about 7 

 centimeters, pierces the walls of the intestine and passes obliquely 

 through its coats for about a centimeter and opens on the surface of 

 a papilla in conjunction with the pancreatic duct. Near its termina- 

 tion it presents a sphincter-like constriction. The walls of the biliary 

 passages are composed of a mucous membrane internally, a fibrous 

 and muscular coat externally. Small racemose glands are embedded 

 in the mucous membrane of the main ducts. 



Physical Properties and Chemic Composition of Bile. The 

 bile obtained directly from the liver through a fistulous opening in 

 the hepatic duct is always thin and watery, while that obtained from 



