Abstract
Chickens which have recovered from an initial Histomonas infection are better hosts for Heterakis gallinarum than chickens which are fully susceptible to Histomonas. Not only do they support more nematodes but the immature worms, measured 12 and 14 days after infection, are larger.Acknowledgements are due to Miss C. N. Hebert who carried out the statistical analysis and to Mr C. C. Norton for technical assistance.