Evidence is put forward to show that eggs of helminth parasites are being constantly re-introduced to land and transferred from one pasture to another. In this way land which has not previously carried poultry for years may yet carry viable eggs which can, and do infect chickens when they are introduced to such runs. The starling and rook are probably important transmitting agents as these congregate among poultry at feeding times. Rabbits and other small rodents may also be carriers but no evidence for this has been looked for yet. Young poultry stock may also become infected with helminths which are normally parasites of wild birds but such parasites, except one Acanthocephalan, have not yet been recovered from or transmitted to older birds experimentally.