690 
CHEMISTRY: J. F. McCLENDON Proc. N. A. S. 
1 Wheeler, W. M., These Proceedings, 3, 1917 (109-117). 
2 Thompson, C. B., and Snyder, T. E., Biol. Bull., Woods Hole, Mass., 36, 1919 
(115-132). 
3 Dewitz, Zs. wiss. Zodl., Leipzig, 30, 1878 (78-105). 
4 Wheeler, W. M., Bull. Amer. Mus. Nat. Hist., New York, 21, 1905 (405^-408). 
6 Shapley, H., Psyche, Boston, 27, 1920 (72-74). 
HYDROGEN ION CONCENTRATION OF THE CONTENTS OF 
THE SMALL INTESTINE 
By J. F. McClendon 
Department of Physioi^ogicaIv Chemistry, University of Minnesota Medicai, 
School 
Communicated by W. A. Noyes, October 8, 1920 
The contents of the small intestine were removed by swallowing a tube 
7 feet long so far down that the outer end was at the teeth and there were 
no loops or coiled portions in the stomach. The tube was of smooth 
rubber, 1 . 5 mm. internal diameter and 3 . 5 mm. external diameter, and 
hence stiff enough to keep from collapsing. A 6-gram iron sinker was 
attached to the lower end to assist in the introduction of the tube. The 
swallowing movements of the oesophagus acting on this sinker pulled the 
tube down. When the tube reached the pylorus, the subject reclined on 
his right side with hips elevated so that the sinker would pass through the 
pyloric sphincter. This passage was accomplished more easily on an 
empty stomach, in fact, in one subject who swallowed the tube after a 
meal, passage of the pylorus was not accomplished until about 4 hours 
had elapsed and repeated trials did not lessen the time required. On an 
empty stomach, passage was accomplished immediately in two subjects, 
as demonstrated by the fact that a darkly bile-stained fluid flowed out of 
the tube. Bile may be regurgitated into the stomach, but is then diluted 
with gastric juice and saliva. The tubes were kept down in two subjects 
for 5 days and 4 nights. The subjects ate their meals regularly, went to 
lectures, went swimming, automobile riding, slept soundly, and, in fact, 
the only inconvenience experienced was consciousness of the presence of the 
ttibe in the throat owing to its stiffness. To alleviate this annoyance they 
ate ice cream and bananas during the afternoon. The withdrawal of the 
tube with sinker attached caused no inconvenience. It required the tube 
about 5 days to descend to its full length and it was examined each day 
with the fluoroscope by Dr. F. S. Bissell, the antimony in the rubber 
easting a distinct shadow. 
The tube was kept clean by forcing distilled water down it when not in 
use. Samples of intestinal contents could be obtained only when digested 
food was coming down from the stomach. At other times hardly a drop 
of fluid could be obtained. The H ion concentration of the individual 
