“…Discussion This paper reports a system of anthelmintic treatment based on the fact that relatively little is known about Eradication of Syphacia obue/ata the longevity of the ova of Syphacia obue/ata. These worms are notoriously difficult to embryonate in any quantity, and the majority of work carried out to date has consequently had to be with natural infections (Chan, 1952b;Brown, Chan & Ferrell, 1954;Brown, Chan & Hussey, 1954;Dunn & Brown, 1962;Simmons, Williams & Wright, 1965;Blair, Thompson & Vandenbelt, 1968). Under various conditions different workers have managed to embryonate and maintain apparently viable ova for periods of 14 (Owen, unpublished data) to 40 (J. W. Lewis & F. H. M. Shava, personal communication) days, but actual longevity under optimal conditions is still not known.…”