THE FUNCTIONS OF THE DIGESTIVE ORGANS. 531 



about the same for several hours. After eating meat, the digestive power 

 for albumin sinks very rapidly during the second hour, only to rise again 

 considerably above its original value in the following hours. Diastase 

 and steapsin behave similarly. 



4gain, the amount of juice depends upon the nature of the food. Bread 

 produces the most secretion, then follows meat, while milk occupies the last 

 place. 



We must mention, in passing, the fact that it has been suggested that 

 the spleen also is related to the secretion of the pancreas, and takes 

 part in activating the trypsinogen. It has been observed that an extract 

 made from the spleen, which has been removed during digestion, strength- 

 ens the action of the pancreatic juice. Pawlow, however, states that he 

 could not find that the secretion produced from animals with the spleen 

 missing had less digestive power than from those with the organ intact. 1 



Under normal conditions, a single foodstuff does not usually come by 

 itself under the influence of the secretion of the pancreas, and of the walls 

 of the intestine, but rather a mixture of foods. The relations are further 

 complicated by reason of the fact that it is not these foods themselves, 

 but rather their cleavage-products, which are acted upon. For the present, 

 the effect of this heterogeneous mixture of products cannot be stated. We 

 can merely assume from the work of Pawlow and his school, performed 

 under uniform conditions, that there are a great many ways here in which 

 the system adapts itself to the prevailing conditions. We have already 

 mentioned the fact that the acid chyme from the stomach does not enter 

 the duodenum in a continuous stream, but that the contents of the stomach 

 leaves it intermittently in relatively small amounts. These portions are 

 at once energetically digested. The products formed by digestion are 

 constantly being absorbed. Even when a very large quantity of food is 

 eaten, there is never a large amount of chyme in the intestine. The extent 

 to which the food is utilized depends, as we shall see later on, largely 

 upon its nature. Naturally the condition of the intestine also comes into 

 consideration. In case of increased peristalsis, the absorption may be 

 lessened. The unabsorbed residue, together with the secretions of bile, 

 pancreas, intestinal membrane and its glands, compose the faeces, or stools. 

 The absorption takes place throughout the entire small intestine, but is 

 undoubtedly most energetic in the jejunum. We must mention in this 

 connection erepsin, which, according to Cohnheim, acts like trypsin upon 

 peptones, and assists in their absorption. 



The chyme is carried on its way by peristalsis. The movements of the 

 intestines are regulated by the central nervous system. Inner vation 

 is provided in part by the vagus and partly by the splanchnic nerves. 



1 Cf. Oskar Prym: Pfliiger's Arch. 104, 433 (1904). 



