314 PHYSIOLOGY OF ALIMENTATION. 



The question of the excretory function of the alimentary 

 tract has also been studied by J. B. MAcCALLUM. 1 This ob- 

 server has confirmed the experiments of some of the older 

 students of oedema that sodium-chloride solutions of the 

 osmotic concentration of the blood, or somewhat higher^ 

 when injected into the circulation of rabbits, cause a greatly 

 increased secretion of fluid into the intestinal tract. The 

 amount of fluid eliminated in this way varies both with the 

 rate and the quantity of the salt solution that is injected. 

 In one experiment in which 500 c.c. of salt solution were 

 injected intravenously, 14.46 percent were eliminated through 

 the intestinal tract. In another experiment 9 percent of 

 the total quantity of fluid injected was eliminated in this 

 way, and in a third, 10.25 percent. When the kidneys are 

 removed the amount excreted through the intestine is some- 

 what higher 16.6 percent in one experiment. The intes- 

 tinal tract behaves therefore not unlike the kidneys under 

 similar circumstances. We are well acquainted with the 

 effect of intravenous injections of salt solutions in increasing 

 the output of urine. The increased secretion from the intes- 

 tinal tract is therefore not unlike the polyuria brought 

 about by similar means. 



Interestingly enough, the other salts which bring about 

 an increased secretion of urine also bring about in a similar 

 way an increased secretion from the intestine. Experiment 

 has shown that the diuretic salts and the saline cathartics 

 are the same. So far as the excretion of water from the body 

 is concerned, therefore, we may well look upon the intestinal 

 tract as supplementary to the kidneys. 



MACCALLUM made no determinations of the relative amounts 

 of the various salts which are eliminated through the kidneys 

 and intestine. It is clear from MENDEL'S experiments, how- 

 ever, that these must differ with the different elements. The 



1 MACCALLUM: University of California Publications, Physiology, 

 1904, 1, p. 125. 



