A Quantitative Method for the Determination of Blood in the Feces of Sheep by Means of the Evelyn Photoelectric Colorimeter*

During the summer of 1938 one of us (J. S. A.), while engaged in experimental work with sheep infected with the stomach-worm, Haemonchus contortus, became interested in making a study of the nature of the anemia produced by these nematodes. The examination of the feces of sheep a few days after artificial infection with stomach-worm larvae revealed the presence of blood. Quantities of blood were also found in the contents of the fourth stomachs of severely infected animals at autopsy. The absence of other lesions in the digestive tract which could have been responsible for the hemorrhage observed showed that the blood came originally from lesions produced by the nematodes in the wall of the fourth stomach. Since these observations indicated that a considerable loss of blood occurred in sheep harboring heavy stomach-worm infections, it appeared to be of interest to make a quantitative study of this loss in an attempt to ascertain its relationship to the anemia observed. To do this it was first necessary to find a method for the quantitative determination of blood in the feces of sheep. A search of the literature revealed that van Eck (1) had published a method for the quantitative determination of blood in human feces. This method, as originally described, was found to be unsatisfactory because of the large quantities of coloring matter and plant fiber present in the feces of sheep. A crude procedure was finally developed which involved the boiling of