Numerous Trichuris vulpis engorged with reddish or pinkish fluid have been found at necropsies of dogs. These worms, when cut, gave strong positive reactions to the benzidine test. Of hundreds of hookworms and whipworms, washed and cut, nearly all were positive with this test. Longitudinal and transverse sections of the slender anterior end of whipworms, when stained with the dilute trichrome stain, gave unmistakable evidence of having blood cells in the esophageal lumen; and a detailed study of the anterior end of the worms indicated the means whereby whipworms can penetrate blood vessels and suck blood. Though less voracious than hookworms, whipworms are, nonetheless, avid blood suckers. Inasmuch as anemia is associated frequently with whipworm infections, a number of investi- gators have sought evidence of blood in these worms. Askanazy (1896), using a special stain- ing technique on over 60 Trichuris trichiura from 12 human cadavers, demonstrated iron- containing pigment in the intestinal epithelial cells, but not in other organs. One whipworm had a doubtful positive; all others were def- initely positive. In addition, he reported a binucleate leukocyte in the worm esophagus in one section. Guiart and Garin (1909) and Garin (1913) obtained positive Weber reac- tions for blood in feces of Trichuris-infected patients, reported blood-engorged whipworms