312 PHYSIOLOGY OF ALIMENTATION. 



large number of instances illustrating the fact that various 

 organic and inorganic substances are eliminated through the 

 alimentary tract. For the most part, however, quantitative 

 determinations, showing the amounts of the various sub- 

 stances eliminated in this way and the amounts cast off 

 through the other emunctories of the body, for instance, the 

 kidneys and skin, have not been made in these earlier experi- 

 mental studies. 



With the especial purpose of determining the relative im- 

 portance of the kidneys and alimentary tract as organs of 

 excretion for certain of the inorganic compounds, MENDEL and 

 his pupils, HANFORD and THACHER, have taken up this 

 problem. 1 



MENDEL and THACHER used strontium (in the form of stron- 

 tium acetate) in their experimental studies, as this' is an ele- 

 ment which does not occur normally in the ordinary labora- 

 tory animals, and hence can be readily recognized in the 

 different tissues spectroscopically. As the experiments were 

 designed to determine the function of the alimentary tract 

 as an excretory organ the salt could not be given by mouth. 

 A four percent solution of strontium acetate was in conse- 

 quence injected subcutaneously with all aseptic precautions, or 

 at times intraperitoneally or intravenously. The animals were 

 kept in metallic cages and the urine and fseces collected 

 separately. A series of experiments performed on dogs, cats, 

 and rabbits yielded the following interesting results. 



Strontium is eliminated only to a small extent through the 

 kidneys, even when this element is introduced in the form of 

 a salt directly into the circulation. The excretion in the 

 urine begins shortly after the injection and usually ceases 

 within twenty-four hours. By far the larger portion of the 

 strontium is excreted through the fseces, and it is immaterial 

 how the element has been given. The place of excretion is 



1 HANFORD: American Journal of Physiology, 1903, IX, p. 235; 

 MENDEL and THACHER: ibid., 1904, XI, p. 7. 



