Intraovular development and moulting of Toxocara pteropodis

Observations of Toxocara pteropodis eggs removed from an adult worm and embryonated in 0.05 M-sulphuric acid showed the first moult to occur on the sixth day followed by the second moult over days 8-11, as indicated by the finding of a transient, loose, double-layered sheath over the definitive cuticle. Infectivity to mice first developed on day 11, reached a maximum at 36 days and then waned over the next 6 months. Details of larval development are described and the significance of loose sheaths on larvae recovered from tissues is discussed.