The Strongyloides Stercoralis (Anguillula Intestinalis) is a very motile worm, about 2 mm. long, and very thin. Is found in the intestine. The embryos were thought to be a different form of parasite and were formerly called A. stercoralis. Occurs in China and is found in some cases of diarrhea. The Trichuris trichiura (Trichocephalus dispar), or "whip worm," is found in the large intestine of man, but is of little pathologic importance.

Is from 4 to 5 cm. long and is peculiar in that the anterior two-thirds are very slender, while the posterior third is thicker.

Fig. 123. - Trichocephalus Dispar (Heller).

a, Female; b, male (natural size).

Fig. 124. - Eggs of Various Worms Found in the Alimentary Canal of Man. X 400 (Mitchell).

a, Ascaris lumbricoides; b, c, Oxyuris vermicularis; d, Trichocephalus dispar; e, Uncinaria duodenale; f, Fasciola hepatica; G, Dicroccelium lan-ceolatum; h, Taenia solium; 1, Taenia saginata; k, Dibothriocephalus latus.

In the male the posterior portion is spirally coiled, in the female is slightly curved.

The eggs are about 0.55 mm. long and at each end have a button-like excrescence.