Date of Award
Dissertation - Restricted
Doctor of Philosophy (PhD)
Harold F. Hardman
Deane N. Calvert
The intestinal parasite, Ascaris lumbricoides, commonly known as Roundworm, belongs to a large group of Helminths, the Nematodes. This group includes many other parasitic species as well as many free living forms. Characteristically , Nematodes have unsegmented, symmetrical, cylindrical or filiform bodies with pointed or rounded ends. Their size is very variable. They have a complete digestive system and no circulatory system (Belding, 1965; Chittwood,1950).
Ascaris lumbricoides owes its name to its resemblance to the common earthworm. It has been over 100 years since Davaine's observation (1863) that ingested ova hatched in the intestine.
Half a century ago (1916) Stewart discovered in rats and mice the indirect cycle of the larvae through the lungs. About the same time Ramson, Foster and Cran (1921) showed that after the preliminary pulmonary cycle the larvae of Ascaris Suum developed to adult worm in the intestine of the hog. In 1922 it was found by Koino that the human parasite had a similar life cycle to the suum variety. ( See Belding's, 1965, book for a historical account).