3 16 PHYSIOLOGY OF ALIMENTATION. 



The above facts, to which many more could be added 

 from medical literature, begin to give us an experimental 

 foundation for the long-established empirical practice of 

 utilizing the intestinal tract as an organ of excretion in those 

 diseases in which the function* of the kidneys is impaired. 

 Not only has it been shown that for many substances the in- 

 testinal tract is the chief excretory organ, but also that the 

 intestine behaves in many respects not unlike the kidneys. 

 The same salts which act as diuretics act as cathartics, and 

 sugar and urea, which by many have been looked upon as 

 substances excreted only by the kidneys, may be lost from 

 the body through the intestinal tract also. 



The problems which suggest themselves in this domain of 

 the excretory function of the alimentary tract, so often touched 

 upon but so little studied, are many. In how far can we sub- 

 stitute the activity of the intestinal tract as an excretory 

 organ for that of the kidneys in ridding the organism of the 

 various substances found in the urine both in health and 

 disease? Each of the substances found in this excretion, 

 from the ordinary salts to the most complex organic poisons, 

 such as the toxins, will have to be investigated with this 

 problem in mind, and the results obtained may well be ex- 



to show sugar in sufficient amounts to be recognized by ordinary 

 laboratory methods even when 600 to 700 grams of sugar were being 

 excreted in the urine. According to experiments carried on with 

 GERTRUDE MOORE, practically no sugar escapes through the gastro- 

 intestinal tract in rabbits rendered diabetic through puncture of the 

 medulla. But this happens in such rabbits as soon as a sodium 

 chloride solution is injected intravenously. A sodium chloride solu- 

 tion too dilute to bring about a glycosuria by itself is able to do this. 

 The sodium chloride therefore renders the gastro-intestinal mucosa 

 permeable in one direction to a substance to which it was formerly 

 impermeable. An analysis of MACCALLUM'S experiments shows that 

 he never injected sodium chloride in sufficient amounts to bring about 

 a glycosuria. He rendered his rabbits diabetic through the use of 

 morphin, and obtained sugar in the gastro-intestinal secretions through 

 subsequent intravenous injections of sodium chloride solution?. 



