. American journal of physiology. m surface for absorption. They arethus quite analogous to the intestinal villi of the vertebrates. The products of proteolysis and, to a much lessdegree, fats and carbohydrates are presumably absorbed by them. As the pyloric end of the stom-ach is approached the characterof the rugae becomes much moresimple, though still adapted toready absorption. No secretingstructures such as the glands ofLieberkiihn occur in the stomach,and no digestive fluid of any kindis elaborated by it, according toour experience. Three large diverticula — thehepatic ducts — open from
. American journal of physiology. m surface for absorption. They arethus quite analogous to the intestinal villi of the vertebrates. The products of proteolysis and, to a much lessdegree, fats and carbohydrates are presumably absorbed by them. As the pyloric end of the stom-ach is approached the characterof the rugae becomes much moresimple, though still adapted toready absorption. No secretingstructures such as the glands ofLieberkiihn occur in the stomach,and no digestive fluid of any kindis elaborated by it, according toour experience. Three large diverticula — thehepatic ducts — open from thestomach into the liver mass, andrapidly divide into smaller ducts,and finally into the minute tubulesof that organ. These diverticulacan hardly be regarded as mereducts for the hepatic secretions,since the characteristic enzymesof the liver are not found in the stomach contents to any largeextent. They apparently serve as caeca in which the final hydrolysisof fats and carbohydrates largely occurs, and where the products of. Figure 6. — Section of cardiac portion ofthe stomach, showing the rugae, j.,sinus;ep., epithelial coat; <•. c. t., vascular con-nective tissue; w. /., muscular layer;/. /., liver tubules ; pig. c, pigment cells. 2 2 Lafayette B. Mendel and Harold C. Bradley ?^ ep. this hydrolysis are absorbed and retained.^ The liver is undoubtedlya secreting organ, as its highly complex glandular epithelium wouldsuggest; but it is equally an organ adapted to digestion, absorption,and retention. A most unique feature of the liver, in this connec-tion, is its function in storing up the metals zinc, copper, and presence of large quantities of the former two metals in the he-patic tissue has already been noted elsewhere,^ and a more completediscussion of the liver must be reserved for a later paper. The pre-sence of the zinc and copper seems to have no effect upon the diges-tive function of the gland with which this paper is more immediately concerned. As
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