iv DIGESTION IN THE INTESTINE 221 



the fatty acids that have been liberated by the action of the 

 pancreatic steapsin. 



Whatever the importance of this coadjuvant function of bile 

 in the processes of digestion and, more particularly, absorption in 

 the intestine, there is no need to exaggerate its significance, and 

 to hold that an animal with a complete and permanent fistula of 

 the gall-bladder must inevitably be considered moribund. The 

 intestine, like all other organs, possesses in a marked degree the 

 power of gradually adapting itself to deficiency of bile. Many 

 animals, when provided with a biliary fistula, as Barbera (1896) 

 observed, recover their original weight, and may live for a long 

 time in perfect health. This occurs with strong dogs operated on 

 in summer. Those, on the contrary, which are operated on in 

 winter and in very cold climates, grow more and more emaciated 

 and eventually perish from marasmus. The former pass the period 

 of adaptation to want of bile in a season at which there is little 

 need of fat as a thermogenic substance, and when the cold weather 

 comes they have established functional adaptation, and bear it 

 without disturbance of nutrition. In the latter, the disturbance 

 of intestinal functions due to the sudden deficit of bile occurs just 

 when there is great need of thermogenic substances to keep up 

 the equilibrium of the thermal balance, and for want of it they 

 consume their own tissues, lose flesh, and die of marasmus. 



Digestion of proteins in vitro by pancreatic juice or extract 

 shows that the complex protein molecule may (independently, 

 according to Kiihne, of the processes of putrefaction) undergo 

 such decomposition and hydrolytic cleavage as to give rise to 

 amino-acids and other simple substances. 



In many analyses of the intestinal contents of dogs fed with 

 flesh, however, Schmidt-Miihlheim finds either no tyrosine, leucine, 

 and aspartic acid, or merely traces of them. Nencki arrived at 

 the same result on examining the matter that escaped from a 

 fistula at the extremity of the small intestine in a woman. All 

 experimenters agree, again, in saying that hardly any peptones 

 occur in the intestinal contents at any period of digestion. 



These differences in the results of artificial and of natural 

 digestion are readily explained on the assumption that the peptone 

 formed is rapidly decomposed, owing to the proteolytic enzyme of 

 the pancreatic juice, more particularly by the intervention of the 

 erepsin of the succus entericus, the crystallisable products that 

 arise (amino-acids) being promptly absorbed and utilised as fast 

 as they are formed. Confirmation of this important statement 

 will be found in the next chapter, when we shall study the 

 absorption of the digestive products of the alimentary proteins. 



The functions of the succus entericus also stand out more 

 clearly and have more significance, when we pass from the results 

 of experiments in vitro to investigation of the physiological 



